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Objectives: Paradoxical associations between high occupational physical activity (OPA) and cardiovascular disease may be explained by exaggerated cardiovascular responses from high work-related stress or low worker fitness. Methods: OPA, blood pressure (BP), heart rate (HR), and rate-pressure product (RPP; HR × BP) were measured objectively for 24 hours in 19 male workers. Work-related stress was measured using the Stress in General Scale. Fitness was estimated using a submaximal treadmill test. Effect modification by work-related stress and fitness on associations between OPA and cardiovascular responses was examined using mixed models with interactions. Results: Associations between OPA and RPP, HR, and BP were stronger with high stress (P < 0.05). Associations of work-time moderate and vigorous physical activity and RPP were attenuatedwith higher fitness (P< 0.05). Conclusions: OPA performed under high work-related stress or by workers with low fitness may exaggerate cardiovascular responses to OPA. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the physical and physiological demands of intercounty camogie match-play between positions and halves of play. Data were collected from 28 players during 18 competitive games using global positioning systems (10-Hz) and heart rate monitors (2.4-GHz). The study demonstrated that intercounty camogie players covered a total distance (TD) (m ± SD) of 6,040 ± 628 m, relative distance (RD) of 83 ± 13 m⋅min-1, and maximum speed of 25 ± 1 km⋅h-1. Furthermore, the players covered a mean sprint distance of 214 ± 112 m and 14 ± 6 sprints. Players' mean heart rate (HRmean) and HRmaxwas 138 ± 23 b⋅min-1 and 164 ± 20 b⋅min-1, respectively. There were decrements between halves in TD (p < 0.01, ES = -0.45), RD (p < 0.01, ES = -0.45), maximum speed (p < 0.05, ES 5 -0.18), HRmax(p < 0.05, ES = -0.23), running (p < 0.01, ES = -0.34), high-speed running (p < 0.01, ES = 0.34), sprinting (p < 0.01, ES 5 -0.10), HRmax(p < 0.05, ES = -0.23), and HRmax % (p < 0.05, ES = -0.24). Midfielders covered a greater TD compared with full-forwards (p < 0.05, ES 5 -0.38) and half-forwards (p < 0.05, ES 5 -0.38). Full-backs covered a significantly lower RD than midfielders (p < 0.05, ES 5 -1.2), half-backs compared with full-forwards (p < 0.05, ES 5 1.14), and half-forwards compared with full-forwards (p < 0.05, ES 5 1.15). Full-forwards covered significantly less RD when compared with half-backs (p < 0.05, ES 5 -1.14), midfielders (p < 0.05, ES 5 -1.47), and half-forwards (p < 0.05, ES 5 -1.15). The findings provide physical and physiological values on the match demands of intercounty camogie match-play. [ABSTRACT FROM AUTHOR]

Competitive collegiate dance combines elements of gymnastics and acrobatics with more traditional styles, such as ballet, jazz, and modern dance. Assessing the physiological demands and identifying clear measures of intensity and duration of such dance provide a framework for planning the competitive season and developing strength and conditioning programs. This study examined the blood lactate (BL), heart rate (HR), and ratings of perceived exertion (RPE) of 14 well-trained female dancers on a competitive collegiate dance team. Subjects completed a treadmill test to determine their lactate threshold (LT) and then performed a 120-second choreographed jazz dance routine in cumulative 30-second segments, during which physiological markers were measured. All subjects exceeded their individually determined LT values by 90 seconds into the dance routine. A moderate (rs = 0.53; p < 0.001) positive correlation was observed between HR and RPE, as was a strong (rs = 0.70; p < 0.001) positive correlation between BL and RPE. Subjects worked at or above LT for much of the 120-second jazz dance routine, indicating that competitive collegiate dance is physiologically demanding and highly anaerobic. Understanding the physiological demands of competitive collegiate dance allows strength and conditioning professionals to develop, monitor, and adjust training parameters, which will aid in minimizing injury and maximizing competitive performance in collegiate dancers. [ABSTRACT FROM AUTHOR]

A comprehensive examination of the external and internal workloads in collegiate women's lacrosse athletes has yet to be reported. Thus, the primary purpose of this study was to determine the absolute and relative external and internal training and game workloads of National Collegiate Athletic Association (NCAA) Division II women's lacrosse athletes throughout an entire season. Data from 19 Division II women's lacrosse athletes were analyzed, encompassing each training session and game across an entire competitive season (February-May). External workloads were assessed using a wearable global positioning system, whereas internal workloads were determined through heart rate (HR) variables and session rating of perceived exertion. Game days were associated with significantly (p < 0.05) greater absolute external and internal workloads. However, when comparing workloads relative to session duration, relative workloads between training and games were no longer significant (p > 0.05) for total distance, high-speed running (≥15 km⋅h-1), HR-derived training impulse, or caloric expenditure. Nonetheless, relative sprint distance (>19 km⋅h-1) was significantly lower during games, whereas high-intensity accelerations (>2 m⋅s-2) and decelerations (<-2 m⋅s-2) were significantly greater during training compared with games (p < 0.05). Practical applications of these findings suggest that coaches can better prepare athletes for game day conditions by adjusting training plans to replicate the duration and intensity of games. Overall, this comprehensive examination of internal and external workloads provides valuable data for coaches and practitioners to support performance comparisons, rehabilitation protocols, and workload analyses in collegiate women's lacrosse athletes. [ABSTRACT FROM AUTHOR]

Longer rest intervals between resistance exercise (RE) sets may promote greater muscle hypertrophy and strength gains over time by facilitating the completion of greater training volume and intensity. However, little is known about the acute neuro-muscular responses to RE sets incorporating longer vs. shorter rest intervals. Using a within-subject, crossover design, 8 healthy, young subjects completed 2 separate acute bouts of 4 sets of 8 x 3-s maximal isometric contractions using either a 2-minute (REST-2) or 5-minute (REST-5) rest interval between sets. Peak torque (PT) and electromyography (EMG) were measured pre and 5 minutes postexercise. Peaktorque and mean torque (MT), EMG, mean, and median frequencies were measured during each set, whereas blood lactate (BLa), heart rate (HR), and rating of perceived exertion (RPE) were measured following each set. Peaktorque and MT were lower (p < 0.05) in sets 3 and 4, and sets 2-4 in REST-2 compared with REST-5, respectively. Electromyography and BL were lower and higher, respectively, in REST-2 vs. REST-5. There was no main effect of condition on HR or RPE. Pre-to-post exercise reductions in PT (-17 ± 9% vs. -4 ± 7%) and EMG (-29 ± 14% vs. -10 ± 7%) were greater (p < 0.001) in REST-2 vs. REST-5. Total exercise volume was less in REST-2 vs. REST-5 (9,748 ± 2296 N⋅m-1 vs. 11,212 ± 2513 N⋅m-1, p < 0.001). These results suggest that incorporating 5-minute between-set rest intervals into a resistance exercise session facilitates improved neuromuscular function, increased exercise volume, and less metabolic stress compared with 2-minute rest intervals. Thus, 5-minute rest intervals may be more efficacious for promoting muscle hypertrophy and strength gains in a chronic resistance training program. [ABSTRACT FROM AUTHOR]

Objective: The safest and most effective exercise stress tests (EST) modalities for long QT syndrome (LQTS) are currently unknown. The main objective was to explore the effects of EST on the corrected QT interval (QTc) in patients with LQTS, and to compare the effects of different EST modalities (cycle ergometer vs treadmill). Data Sources: Systematic searches were performed in September 2022 in accordance with the PRISMA statement through PubMed, Medline, EBM Reviews, Embase, and Web of Science. Main Results: A total of 1728 patients with LQTS, whether congenital or acquired, without any age restrictions (pediatric age#18 years and adult age.19 years), and 2437 control subjects were included in the 49 studies. The QT interval data were available for 15 studies. Our analyses showed that the QT interval prolonged in a similar manner using either a cycle ergometer or a treadmill (standardized mean difference [SMD] 5 1.89 [95% CI, 1.07-2.71] vs SMD 5 1.46 [95% CI, 0.78-2.14], respectively). Therefore, it seems that either modality may be used to evaluate patients with LQTS. Conclusions: The methodology for the measurement of the QT interval was very heterogeneous between studies, which inevitably influenced the quality of the analyses. Hence, researchers should proceed with caution when exploring and interpreting data in the field of exercise and LQTS. [ABSTRACT FROM AUTHOR]

Purpose: To compare the development of fatigability during a moderate-intensity cycling exercise between women with fibromyalgia (FM) and control women (CON) after acute ingestion of caffeine and placebo. Methods: Ten FM and 10 CON women performed a 30-min moderate-intensity cycling exercise 1 h after the ingestion of a capsule containing either caffeine or a placebo. Fatigability and its central and peripheral determinants were determined via changes from pre- to post-15 and post-30 min of exercise in maximal voluntary isometric contractions, voluntary activation (VA), and quadriceps potentiated twitch torque (Qtw-pot), respectively. Heart rate, muscle oxygen saturation, perceptive responses, mood state, localized and widespread pain, and sleepiness were also monitored during and after exercise. Results: There was a time versus group interaction for maximal voluntary isometric contraction and VA (P < 0.001) but not for Qtw-pot (P = 0.363), indicating a greater rate of fatigability development, mainly caused by central mechanisms, in the FM than in the CON group. There was also a main effect of condition for VA (P = 0.011), indicating that caffeine attenuates central mechanisms of fatigability in both groups. Caffeine ingestion also increased muscle oxygenation, perceived vigor, and energy, and decreased leg muscle pain, sleepiness, and perceived fatigue in both groups. However, caffeine improved perceived pleasure/displeasure and exercise adherence likelihood only in the FM group. Conclusions: Compared with CON, women with FM present a greater rate of fatigability during exercise, mainly of central origin. Caffeine seems to be a promising bioactive to counteract the central mechanisms of fatigability and improve the exercise experience among FM women. [ABSTRACT FROM AUTHOR]

Purpose: Cardiorespiratory fitness (CRF) measured by peak oxygen consumption (...) declines with aging and correlates with mortality and morbidity. Cardiopulmonary exercise testing (CPET) is the criterion method to assess CRF, but its feasibility, validity, and reliability in older adults are unclear. Our objective was to design and implement a dependable, safe, and reliable CPET protocol in older adults. Methods: ... was measured by CPET, performed using treadmill exercise in 875 adults ≥70 yr in the Study of Muscle, Mobility and Aging (SOMMA). The protocol included a symptom-limited peak (maximal) exercise and two submaximal walking speeds. An adjudication process was in place to review tests for validity if they met any prespecified criteria (... <12.0 mL⋅kg-1⋅min-1; maximum heart rate <100 bpm; respiratory exchange ratio <1.05 and a rating of perceived exertion <15). A subset (N = 30) performed a repeat test to assess reproducibility. Results: CPET was safe and well tolerated, with 95.8% of participants able to complete the // phase of the protocol. Only 56 (6.4%) participants had a risk alert and only two adverse events occurred: a fall and atrial fibrillation. Mean ± SD ... was 20.2 ± 4.8 mL⋅kg-1⋅min-1, peak heart rate 142 ± 18 bpm, and peak respiratory exchange ratio 1.14 ± 0.09. Adjudication was indicated in 47 tests; 20 were evaluated as valid and 27 as invalid (18 data collection errors, 9 did not reach ...). Reproducibility of ... was high (intraclass correlation coefficient = 0.97). Conclusions: CPET was feasible, effective, and safe for older adults, including many with multimorbidity or frailty. These data support a broader implementation of CPET to provide insight into the role of CRF and its underlying determinants of aging and age-related conditions. [ABSTRACT FROM AUTHOR]

Objective: The aim of the study was to compare the effectiveness of a telerehabilitation exercise program versus "wait-and-see" on physical exertion, quality of life, dyspnea severity, heart rate, and oxygen saturation in patients with post-COVID fatigue and dyspnea. Design: Sixty-four patients were enrolled in this randomized clinical trial. A telerehabilitation program based on patient education, physical activity, airway clearing, and breathing exercise interventionswas conducted. Self-perceived physical exertion during daily living activities, dyspnea severity, health-related quality of life and physiological outcomes, and the 6-min walking test were assessed at baseline, after the program and at 1- and 3-mo follow-up periods. Results: The experimental group experienced greater improvements in self-perceived physical exertion during daily living activities, dyspnea severity, health-related quality of life, and 6-min walking test (all, P < 0.001). In addition, patients undergoing the telerehabilitation program reported lower exertion scores at rest and after the 6-min walking test (both, P < 0.001). Between-group oxygen saturation differences were found at rest ( P < 0.001), but not after the 6-min walking test ( P = 0.024). Finally, significant between-group differences were found for heart rate after the 6-min walking test ( P < 0.001). Conclusions: Although both groups showed a significant improvement after 3 mos of follow-up, the group receiving the telerehabilitation program described a greater improvement compared with the group receiving no intervention. [ABSTRACT FROM AUTHOR]

BACKGROUND: A dual-chamber leadless pacemaker system has been designed for atrioventricular synchronous pacing using wireless, beat-to-beat, implant-to-implant (i2i) communication between distinct atrial and ventricular leadless pacemakers. The atrioventricular synchrony achieved across various ambulatory scenarios has yet to be systematically evaluated. METHODS: A prospective, single-arm, unblinded, multicenter, international clinical trial of the leadless pacemaker system was conducted in patients with a conventional dual-chamber pacing indication enrolled from February 2022 to March 2023. Leadless pacemaker systems were implanted, and 12-lead Holter electrocardiographic recordings were collected 3 months after implantation over various postures/activities: sitting, supine, left lateral recumbent, right lateral recumbent, standing, normal walk, and fast walk. An independent Holter core laboratory performed a manual adjudication of the percent of atrioventricular synchronous beats using the standard 300-millisecond PR interval limit. Atrium-to-ventricle and ventricle-to-atrium i2i communication success rates were also assessed. Post hoc summary statistics describing the relationships between atrioventricular synchrony and i2i success, posture/activity, implantation indication, atrioventricular event, and heart rate were calculated. RESULTS: In the evaluable population (n=384 of 464 enrolled [83%]; 61% male; age, 70 years; weight, 82 kg; 60% ejection fraction; 95% of beats evaluable), the mean atrioventricular synchrony of 98% of beats observed across all postures using the standard 300-millisecond limit was greater than both atrial-to-ventricular i2i (94%) and ventricular-to-atrial i2i (94%; P<0.001), exceeding both i2i values in 95% of patients. Atrioventricular synchrony was achieved in >95% of evaluable beats across all postures/activities, implantation indications, atrioventricular paced/sensed event combinations, and heart rate ranges (including >100 bpm). CONCLUSIONS: This dual-chamber leadless pacemaker system demonstrated atrioventricular synchrony in 98% of evaluable beats at 3 months after implantation. Atrioventricular synchrony was maintained across postures/activities and remained robust for heart rates >100 bpm. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to investigate the effects of a 7-d high-intensity interval training shock microcycle (HIIT-SM) with or without additional low-intensity training (LIT) on aerobic fitness and endurance performance compared with a control group (CG). Methods: Thirty-three endurance-trained athletes (7 women, 26 men, mean ± SD: age, 30.2 ± 6.9 yr;maximal oxygen uptake (VO2max), 59.8 ± 4.9 mL·min-1·kg-1) performed exercise testing at T1 and were randomly assigned to one of three groups: i) HSM, 10 running-based HIIT sessions (5 × 4 min at 90%-95% maximal heart rate) over 7 d; ii)HSM+ LIT, equal toHSMwith additional 30 min of LIT after each HIIT; iii) CG, regular training. Exercise testing was repeated 3 d (T2), 7 d (T3), and 14 d (T4) after the intervention. A 5-km time trial (TT5km) was performed 3-4 d before T1 and 10-11 d after the intervention. Data were analyzed by two-way repeated-measures ANOVA. Results: No interaction effect was found for VO2max (P = 0.170, pη² = 0.09), peak power output (P = 0.734, pη² = 0.04), and work economy (P = 0.804, pη² = 0.03). There was an interaction for velocity at lactate threshold (P = 0.006, pη² = 0.18) with increased velocity in HSM at T2 (3.2%, P = 0.030), T3 (4%, P = 0.006), T4 (4%, P = 0.003), as well as in HSM + LIT for T2 (3.2%, P = 0.011), whereas CG showed no change. There was an interaction for TT5km (P = 0.044, pη² = 0.19), with HSM improving 2.7% (P = 0.003) and HSM + LIT 2.3% (P = 0.010), whereas CG was, on average, -0.3% (P = 0.821) slower. Conclusions: HIIT-SM with or without additional LIT has negligible effects on VO2max but improves other key endurance variables in endurance-trained athletes. No superiority of either intervention group was demonstrated. Therefore, additional LIT during HIIT-SM is not beneficial. [ABSTRACT FROM AUTHOR]

Despite having to carry the same occupational load, female soldiers tend to be lighter than male soldiers. The aim of this study was to determine the differences in cardiovascular load between female and male US Marine recruits during progressive load carriage hikes. United States Marine Corps recruits (565 male recruits; 364 female recruits) completed 6 loaded hikes over 6 weeks (1:10 kg, 30 minutes; 2: 10 kg, 45 minutes; 3: 15 kg, 30 minutes, 4: 15 kg, 45 minutes; 5: 20 kg, 30 minutes; 6: 20 kg, 45 minutes) during which cardiovascular response was measured. Average heart rate (HRavg), HR maximum (HRmax), and pace were measured via a wrist-worn physiological monitor. Independent sample t-tests were conducted to compare between sexes, with significance set at 0.008 after adjusting for multiple comparisons. The average female recruit had significantly lower body mass (BM) compared with the average male recruit (p < 0.001) and thus carried a significantly heavier relative load. (10 kg ~17%, 15 kg ~25%, 20 kg ~33%, p < 0.001). There were no significant differences in pace in any hike, and no significant differences were found in HRavg or HRmax when comparing female and male Marines during Hike 1. For female Marines, HRavg was significantly higher compared with male Marines during Hike 2 (+6.5 b⋅min-1, p < 0.001) and Hike 3 (+7.4 b⋅min-1, p < 0.001), and both HRavg and HRmax were significantly higher in Hike 4 (+11.9 b⋅min-1, +8.4 b⋅min-1, p < 0.001), Hike 5 (+7.7 b⋅min-1, +7.9 b⋅min-1, p < 0.001), and Hike 6 (+6.9 b⋅min-1, +7.1 b⋅min-1, p < 0.001), respectively. Female Marines endured greater cardiovascular demand compared with male Marines during load carriage events when carrying loads greater than 15 kg (~25% BM). [ABSTRACT FROM AUTHOR]

Field referees (FRs) need to move throughout the pitch to identify any infringements of the game's laws. Their performance depends on technical, tactical, physical, physiological, and mental factors. This retrospective study aimed to examine and assess the physical and physiological parameters as a function of time in elite association football referees during official matches. Global positioning system (match time, distance in different intensity ranges [low-intensity, high-speed, very high-speed running, and sprinting], average and peak speed, distance in accelerations or decelerations) and heart rate (average and peak) data from 212 national and international football matches were analyzed. A linear mixed-model analysis was performed to assess the differences between halves and between the three 15-minute sections of each half-time for all the physical and physiological variables collected. A significant effect of match half was found for the game time (p < 0.001) and the standing time (p = 0.005), both higher in the second half, and for the average speed (p = 0.017), which was lower in the second half. Total distance (p < 0.001), low-intensity distance (p = 0.004), and average speed (p = 0.007) all showed a reduction as a function of time. More than 7.800 high-speed intervals were detected. Accelerative actions within 3 seconds characterized most of the high-speed efforts of an FR during a match. Significant differences emerged in the way the match intensity is distributed across the match, analyzed both in halves (first vs. second) and 15-minute intervals within each half. It is important to emphasize the importance of high-speed training with a focus on a faster transition from low- to high-speed running to keep up with the play to get into an appropriate position and subsequently make the correct decisions. [ABSTRACT FROM AUTHOR]

Comparisons of high-load with low-load resistance training (RT) exercise have demonstrated no differences in postexercise metabolism when volume is matched. This important limitation of matching or equating volume diminishes benefits of the low-load RT protocol. Therefore, the purpose of this study was to determine the effects of acute low-load high volume and high-load low volume RT protocols completed to volitional fatigue on postexercise metabolism. Eleven recreationally active resistance-trained male subjects (24 ± 2 years; BMI: 25.3 ± 1.5 kg⋅m-2) completed 3 experimental sessions: (a) no-exercise control (CTRL); (b) RTat 30% 1 repetition maximum (1RM; 30% 1RM); and (c) RT at 90% 1RM (90% 1RM) with oxygen consumption (...2) measurements 2 hours postexercise. The RT sessions consisted of 3 sets of back squats, bench press, straight-leg deadlift, military press, and bent-over rows to volitional fatigue completed sequentially with 90 seconds of rest between sets and exercises. Changes were considered important if p < 0.100 with a ≥medium effect size. ...o2 1 hour postexercise was elevated following 30% 1RM (25%; p = 0.003, d = 1.40) and 90% 1RM (14%; p = 0.010, d = 1.15) vs. CTRL and remained elevated 2 hours postexercise following 30% 1RM (16%; p = 0.010, d = 1.15) vs. CTRL. Total O2 consumed postexercise increased following 30% 1RM and 90% 1RM (~17%; p < 0.044, d > 0.91) vs. CTRL. Fat oxidation was elevated 1 hour post-exercise following 30% 1RM and 90% 1RM (~155%; p < 0.001, d > 2.97) and remained elevated 2 hours postexercise following 30% 1RM compared with CTRL and 90% 1RM (~69%; p < 0.030, d > 1.03). These data demonstrate beneficial changes to postexercise metabolism following high- and low-load RT sessions, with more prolonged effects following the low-load RT protocol completed to volitional fatigue. [ABSTRACT FROM AUTHOR]

Different approaches exist for characterizing athletes, e.g., physiological and locomotor profiling. The aims of this study were to generate and compare physiological and locomotor profiles of male and female runners and to evaluate relationships between the different approaches. Thirty-four highly trained adolescent and young adult female and male athletes (n = 11 sprinters; n = 11,400-m runners; n = 12 middle-distance runners) performed two 100-m sprints on a running track to determine maximal sprinting speed (MSS) and maximal lactate accumulation rate (ċLamax). A cardiopulmonary exercise test was performed on a treadmill to determine maximal aerobic speed (MAS) and maximal oxygen uptake (...o2max). Anaerobic speed reserve (ASR) was calculated as the difference between MSS and MAS. Group comparisons were conducted with a 2-way ANOVA (discipline x sex; p < 0.05) and Bonferroni post hoc tests and Cohen's d as effect size. Parameters were correlated by Pearson's correlation coefficients. Maximal aerobic speed and ...o2max were higher in 400-m and middle-distance runners compared with sprinters (p ≤ 0.02; -2.24 ≤ d ≤ -1.29). Maximal sprinting speed and ċLamax were higher in sprinters and 400-m runners compared with middle-distance runners (0.03 ≤ p ≤ 0.28; 0.73 ≤ d ≤ 1.23). Anaerobic speed reserve was highest in sprinters and lowest in middle-distance runners (p ≤ 0.03; 1.24 ≤ d ≤ 2.79). High correlations were found between ASR and MAS, MSS, and ċLamax (p < 0.01; -0.55 ≤ r ≤ 0.91) and between ċLamax and MSS (p < 0.01; r = 0.74). Our results indicate that athletes of different sprinting and running disciplines show differing physiological and locomotor profiles, and that the parameters of these approaches are related to each other. This can be of interest for assessing strengths and weaknesses (e.g., for talent identification) or training prescription in these disciplines. [ABSTRACT FROM AUTHOR]

Purpose: To determine in trained females and males i) the agreement between the gas exchange threshold (GET), lactate threshold 1 (LT1), and heart rate variability threshold 1 (HRVT1), as well as between the respiratory compensation point (RCP), lactate threshold 2 (LT2), and heart rate variability threshold 2 (HRVT2), and ii) the reproducibility of HRVT1 and HRVT2 during 2-min incremental step protocols. Methods: Fifty-seven trained participants (24 females) completed a 2-min step incremental test to task failure. Nineteen participants (eight females) completed a second test to evaluate reproducibility. Gas exchange and ventilatory responses, blood lactate concentration, and RR time series were recorded to assess the oxygen consumption (...) and heart rate (HR) associated with the GET, RCP, LT1, LT2, HRVT1, and HRVT2. Results: /-GET versus ...-HRVT1 and HR-GET versus HR-HRVT1 were statistically different for females (29.5 ± 4.0 vs 34.6 ± 6.1 mL⋅kg-1⋅min-1; 154 ± 11 vs 166 ± 12 bpm) and for males (33.9 ± 4.2 vs 42.7 ± 4.6 mL⋅kg-1·min-1; 145 ± 11 vs 165 ± 9 bpm; P < 0.001). ... and HR at HRVT1 were greater than at LT1 (P < 0.05). ...-RCP versus ...-HRVT2 and HR-RCP versus HR-HRVT2 were not statistically different for females (40.1 ± 4.7 vs 39.5 ± 6.7 mL⋅kg-1⋅min-1; 177 ± 9 vs 176 ± 9 bpm) and males (48.4 ± 5.4 vs 47.8 ± 4.8mL⋅kg-1⋅min-1; 176 ± 8 vs 175 ± 9 bpm; P > 0.05). ... and HR responses at LT2 were similar to HRVT2 (P > 0.05). Intraclass correlation coefficient for .-HRVT1, HR-HRVT1, ...-HRVT2, and HR-HRVT2 indicated good reproducibility when comparing the two different time points to standard methods. Conclusions: Whereas HRVT2 is a valid and reproducible estimate of the RCP/LT2, current approaches for HRVT1 estimation did not show good agreement with outcomes at GET and LT1. [ABSTRACT FROM AUTHOR]

Introduction: This study assessed the effect of individualized, domain-based exercise intensity prescription on changes in maximal oxygen uptake (...) and submaximal thresholds. Methods: Eighty-four young healthy participants (42 females, 42males) were randomly assigned to six age, sex, and ...-matched groups (14 participants each). Groups performed continuous cycling in the 1) moderate (MOD), 2) lower heavy (HVY1), and 3) upper heavy-intensity (HVY2) domain; interval cycling in the form of 4) high-intensity interval training (HIIT) in the severe-intensity domain, or 5) sprint-interval training (SIT) in the extreme-intensity domain; or no exercise for 6) control (CON). All training groups, except SIT, were work-matched. Training participants completed three sessions per week for 6 wk with physiological evaluations performed at PRE, MID, and POST intervention. Results: Compared with the change in ... (...) in CON (0.1 ± 1.2 mL⋅kg-1⋅min-1), all training groups, exceptMOD (1.8 ± 2.7 mL⋅kg-1⋅min-1), demonstrated a significant increase ( P < 0.05). HIIT produced the highest increase (6.2 ± 2.8 mL⋅kg-1⋅min-1) followed by HVY2 (5.4 ± 2.3 mL⋅kg-1⋅min-1), SIT (4.7 ± 2.3 mL⋅kg-1⋅min-1), and HVY1 (3.3 ± 2.4 mL⋅kg-1⋅min-1), respectively. The ΔPO at the estimated lactate threshold (θLT) was similar across HVY1, HVY2, HIIT, and SIT, which were all greater than CON (P < 0.05). The ... and ΔPO at θLT for MOD was not different from CON (P > 0.05). HIIT produced the highest ΔPO at maximal metabolic steady state, which was greater than CON, MOD, and SIT (P < 0.05). Conclusions: This study demonstrated that i) exercise intensity is a key component determining changes in ... and submaximal thresholds and ii) exercise intensity domain-based prescription allows for a homogenous metabolic stimulus across individuals. [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is Available in the Text. This is the first study in humans demonstrating noninvasive modulation of insula subregions to affect pain ratings, brain physiology related to pain (the contact heat–evoked potential), and also metrics of autonomic/cardiovascular activity including heart-rate variability. The insula is an intriguing target for pain modulation. Unfortunately, it lies deep to the cortex making spatially specific noninvasive access difficult. Here, we leverage the high spatial resolution and deep penetration depth of low-intensity focused ultrasound (LIFU) to nonsurgically modulate the anterior insula (AI) or posterior insula (PI) in humans for effect on subjective pain ratings, electroencephalographic (EEG) contact heat–evoked potentials, as well as autonomic measures including heart-rate variability (HRV). In a within-subjects, repeated-measures, pseudo-randomized trial design, 23 healthy volunteers received brief noxious heat pain stimuli to the dorsum of their right hand during continuous heart-rate, electrodermal, electrocardiography and EEG recording. Low-intensity focused ultrasound was delivered to the AI (anterior short gyrus), PI (posterior longus gyrus), or under an inert Sham condition. The primary outcome measure was pain rating. Low-intensity focused ultrasound to both AI and PI similarly reduced pain ratings but had differential effects on EEG activity. Low-intensity focused ultrasound to PI affected earlier EEG amplitudes, whereas LIFU to AI affected later EEG amplitudes. Only LIFU to the AI affected HRV as indexed by an increase in SD of N-N intervals and mean HRV low-frequency power. Taken together, LIFU is an effective noninvasive method to individually target subregions of the insula in humans for site-specific effects on brain biomarkers of pain processing and autonomic reactivity that translates to reduced perceived pain to a transient heat stimulus. [ABSTRACT FROM AUTHOR]

Objective: The aim of the study is to determine the impact of emergency call volume on exertion, autonomic activity, and sleep among urban structural firefighters. Methods: Thirty-four firefighters wore a wrist-based monitor to track sleep and autonomic parameters and rated their level of perceived exertion (Borg Rating of Perceived Exertion) and subjective sleepiness after a 24-hour shift. Predictive variables included total run time and total run time after 11:59 PM. Results: Total run time and sleep duration accounted for Borg Rat- ing of Perceived Exertion and subjective sleepiness, while total run time and to- tal run time after 11:59 PM accounted for sleep durations on-duty. Conclu- sions: The current results suggest that emergency call volume is associated with indicators of exertion and sleep. As such, call volume tracking is an important consideration for departments to ensure personnel readiness and wellness and provide a method of tracking the occupational demands experienced by fire- fighters on-duty. [ABSTRACT FROM AUTHOR]

Objective: ST segment deviations around the isoelectric line are common findings in manifest cardiovascular disease. In athletes, ST elevation is common, while ST depression is considered rare. However, clinical studies in athletes have associated ST depression with myocardial fibrosis and fatty infiltration and ST elevation with pericarditis and myocarditis. This study aims to explore the association between resting ST segment deviations and resting heart rate, an indicator of training and autonomic tone and electrocardiography (ECG) markers of exercise training effect and cardiovascular health R and T wave amplitude. Design: Retrospective analysis of digitized ECG data. Setting: Institutional setting. Participants: Seven thousand eight hundred thirty-six (male athletes = 4592, female athletes = 3244) healthy asymptomatic athletes (14-35 years). Main outcome measures: A series of correlations and regressions were conducted between ST depression (<0.0 µV) and ST elevation (>0.0 µV), on R and T wave amplitudes, and heart rate in leads V2, V5, and aVF. Results: Positive correlations between ST elevation and R and T wave (S wave in V2) amplitudes and leads V5, V2, and aVF in male and female athletes (range of r = 0.1-0.54). In addition, there was a negative correlation between ST elevation and HR for male and female athletes. Finally, there was a negative correlation between ST depression and R wave and HR for male and female athletes in V5 ( P < 0.01). Conclusions: In athletes, ST segment elevation is correlated with R and T wave amplitudes and negatively correlated with HR. In addition, ST segment elevation is correlated with low heart rate, consistent with its higher prevalence in athletes. ST segment depression is not influenced by HR but is negatively associated with R and T wave amplitudes. [ABSTRACT FROM AUTHOR]

We examined the endocrine responses of 16 (female = 8) resistance trained volunteers to a single bout of whole-body high-volume load resistance exercise in hot (HOT; 40° C) and temperate (TEMP; 20° C) environmental conditions. Thermoregulatory and heart rate (HR) data were recorded, and venous blood was acquired before and after resistance exercise to assess serum anabolic and catabolic hormones. In men, testosterone increased after resistance exercise in HOT and TEMP (p < 0.01) but postexercise testosterone was not different between condition (p = 0.51) In women, human growth hormone was different between condition at pre-exercise (p = 0.02) and postexercise (p = 0.03). After controlling for pre-exercise values, the between-condition postexercise difference was abolished (p = 0.16) There were no differences in insulin-like growth factor-1 for either sex (p >= 0.06) In women, cortisol increased from pre-exercise to postexercise in HOT (p = 0.04) but not TEMP (p = 0.19) generating a between-condition difference at postexercise (p < 0.01) In men, cortisol increased from pre-exercise to postexercise in HOT only (p < 0.01) Rectal temperature increased to a greater extent in HOT compared with TEMP in both men (p = 0.01) and women (p = 0.02) Heart rate increased after exercise under both conditions in men and women (p = 0.01), but only women experience greater postexercise HR in HOT vs. TEMP (p = 0.04) The addition of heat stress to resistance exercise session did not overtly shift the endocrine response toward an anabolic or catabolic response. When acute program variables are prescribed to increase postresistance exercise anabolic hormones, adding heat stress is not syner- gistic but does increase physiologic strain (i.e., elevated HR and rectal temperature). [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to determine the effect of video calling between preterm infants treated in the neonatal intensive care unit (NICU) and their mothers on the physiological parameters of infants and mother-infant bonding. Background: Preterm infants need prolonged treatment in the NICU, and their families may have difficulty seeing their babies during this treatment process. Methods: This is a prospective, randomized-controlled, experimental study. The study sample consisted of 75 preterm infants and their mothers. The data were collected using a maternal introductory information form, a preterm infant introductory information form, a preterm infant physiological parameters follow-up form, and the Mother-Infant Bonding Scale (MIBS). The study included 3 study groups: the video call group, the video call with lullaby group, and the control group. Video calls between preterm infants and their mothers were made through Zoom for 5 to 10 minutes daily for 7 days. The mothers filled out the MIBS online before and on the 7th and 30th days of the study. Results: Preterm infants in the video call and the video call with lullaby groups had higher MIBS mean scores on the 7th and 30th days of the study than their pretest MIBS scores. Preterm infants in the video call and the video call with lullaby groups had statistically significantly higher MIBS mean scores on the seventh day of the study than those in the control group. At the end of the 7-day study period, there was an improvement in the physiological parameters of preterm infants in the video call group and the video call with lullaby group compared with those in the control group, and this relationship was statistically significant. Conclusions: In conclusion, the implementation of video calls between mothers and preterm infants in NICUs had a healing effect on the physiological parameters of preterm infants and increased mother-infant bonding. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to investigate the effect of white noise on pain response, heart rate, and oxygen saturation during heel puncture in premature infants. Methods: A randomized, controlled, pretest-posttest design was used. The participants were premature infants admitted to the neonatal intensive care unit of a university hospital in Gyeonggi Province. Sixty premature infants were assigned to either an experimental (n = 30) or control (n = 30) group. The experimental group was exposed to white noise during heel puncture, and the measured variables were pain response, heart rate, and oxygen saturation. The data were analyzed using the independent t test, chi-squared test, and analysis of covariance. Results: Premature infants in the experimental group had a lower pain response and heart rate than the control group (F = 81.26, P < .01; F = 7.05, P = .01), and higher oxygen saturation than the control group (F = 4.76, P = .03). Conclusion: These results demonstrated that the white noise intervention is an effective nursing intervention to reduce the pain response and stabilize heart rate and oxygen saturation in premature infants during heel puncture. [ABSTRACT FROM AUTHOR]

Introduction: Maternal speech has been shown to benefit premature infants by improving feeding outcomes and potentiating the development of the auditory cortex. To our knowledge, limited studies have addressed the benefits of exposure to maternal speech on neural development in premature infants. The objective of this study was to investigate the effect of early controlled exposure to maternal recording a passage of speech on heart rate variability (obtained before, during, and after playback of a test stimulus of a female stranger speaking the same passage) in very low-birth-weight premature infants tracked weekly from 28 to 34 weeks. Methods: Prospective, randomized controlled trial, longitudinal, and repeated-measures design were conducted on 49 subjects. Infants heard a recording of their mother's speech twice a day from either 28 to 34 weeks (group 1) or from 32 to 34 weeks (group 2). Spectral analysis was measured weekly for 45 seconds before, during, and after playback of maternal speech. A generalized linear mixed model was conducted to examine the 2-way interaction in the log high-frequency power between groups, genders, sessions, and conditions. Results: It was found that there were no significant differences between groups before, during, and after playback of the stimulus. A significant difference, however, was noted between conditions (before vs during period). Conclusion: It can be concluded cautiously that playing back of maternal speech recordings to the premature infant has a beneficial impact on neural development after 32 weeks gestational age. [ABSTRACT FROM AUTHOR]

This study compared handheld dynamometry (HHD) at the weakest point of the strength curve for hip extensors, hip abductors, and knee extensors in older adults and onerepetition maximum (1RM) of that same muscle groups with cuff weights. Fifty participants (62-94 years) were tested. Paired t tests indicated no significant differences between the 2 measures. Reliability testing for absolute agreement between 1RM and HHD yielded intraclass correlations of good to excellent. This demonstrates HHD at or near the weakest point of a muscle group provides an accurate measure of older individual's 1RM for knee extension, hip extension, and hip abduction. [ABSTRACT FROM AUTHOR]

The purpose of this study was to test the efficacy of lavender aromatherapy via inhalation as a stress management modality for patients in cardiac rehabilitation. This was a quasi-experimental design. Aromatherapy was provided via inhalation to participants before a cardiac rehabilitation session over 8 minutes using lavender essential oil. The same protocol was used in the non-aromatherapy session without the essential oil. Blood pressure and radial pulse were measured, and subjective data were also collected including assessment of stress level (1-10 scale) and affect using the Positive and Negative Affect Schedule (PANAS). Analyses were performed using SPSS Statistics version 20. Quantitative measures were analyzed using Mann-Whitney nonparametric equivalent to the t test. Inferential measures were analyzed using the χ2 or Fisher's exact test. In the outpatient cardiac rehabilitation program, 25 patients participated in this study. The average change in negative affect (PANAS−) between pre and post-aromatherapy compared with pre- and post-non-aromatherapy sessions was statistically significant. Results showed a reduction in blood pressure following both aromatherapy and non-aromatherapy sessions with no statistical significance between sessions. Heart rate decreased equally post-aromatherapy and non-aromatherapy sessions. Aromatherapy may be a useful stress management tool for cardiac rehabilitation patients. [ABSTRACT FROM AUTHOR]

Development and Calibration of a PATCH Device for Monitoring Children's Heart Rate and Acceleration. Med. Sci. Sports Exerc., Vol. 56, No. 6, pp. 1196-1207, 2024. Introduction: Current wearables that collect heart rate and acceleration were not designed for children and/or do not allow access to raw signals, making them fundamentally unverifiable. This study describes the creation and calibration of an open-source multichannel platform (PATCH) designed to measure heart rate and acceleration in children ages 3-8 yr. Methods: Children (N = 63; mean age, 6.3 yr) participated in a 45-min protocol ranging in intensities from sedentary to vigorous activity. Actiheart-5 was used as a comparison measure. We calculated mean bias, mean absolute error (MAE) mean absolute percent error (MA%E), Pearson correlations, and Lin's concordance correlation coefficient (CCC). Results: Mean bias between PATCH and Actiheart heart rate was 2.26 bpm, MAE was 6.67 bpm, and M%E was 5.99%. The correlation between PATCH and Actiheart heart rate was 0.89, and CCC was 0.88. For acceleration, mean bias was 1.16 mg and MAE was 12.24 mg. The correlation between PATCH and Actiheart was 0.96, and CCC was 0.95. Conclusions: The PATCH demonstrated clinically acceptable accuracies to measure heart rate and acceleration compared with a research-grade device. [ABSTRACT FROM AUTHOR]

Purpose: Muscle mechanics is paramount in our understanding of motor performance. However, little is known regarding the sensitivity of fascicle dynamics and connective tissues stiffness to exercise duration and ambient temperature during running, both increasing muscle temperature. This study aimed to determine gastrocnemius medialis (GM) fascicle dynamics in vivo during running in temperate and hot conditions, as well as muscle-tendon unit responses. Methods: Using ultrafast ultrasound, 15 participants (8 men, 7 women; 26 ± 3 yr) were tested before, during (2 and 40 min), and after a running task (40 min at 10 km⋅h-1) in temperate (TEMP; ~23°C) and hot (HOT: ~38°C) conditions. Results: Although core, skin temperatures, and heart rate increased from the beginning to the end of the exercise and in a larger extent in HOT than TEMP (P < 0.001), the physiological stress elicited did not alter running temporal parameters and GM fascicle operating lengths, with similar behavior of the fascicles on their force-length relationship, over time (2 vs 40 min) or across condition (TEMP vs HOT; P ≥ 0.248). Maximal voluntary force production did not reported statistical changes after exercise (P = 0.060), and the connective tissues stiffness measured (i.e., passive muscle and stiffness of the series-elastic elements) did not show neither time (P ≥ 0.281), condition (P ≥ 0.256) nor time-condition interaction (P ≥ 0.465) effect. Conclusions: This study revealed that prolonged running exercise does not alter muscle-tendon unit properties and interplay, which are not influenced by ambient temperature. These findings may rule out potential detrimental effects of heat on muscle properties and encourage further investigations on longer and more intense running exercise. [ABSTRACT FROM AUTHOR]

Objectives: To determine the impact of cardiorespiratory fitness (CRF) on physiological and performance outcomes during a 120-m vertical high-rise ascent in firefighters with CRF levels at or above (higher-fit) and below (lower-fit [LF]) the national recommended minimum physical employment standard (VO2max 42.3 mL·kg-1·min-1). Methods: Twenty-eight firefighters completed two high-rise firefighting trials (continuous and discontinuous ascent with predetermined 1-minute rest breaks). Task time, heart rate, ratings of perceived exertion, core body temperature, and thermal comfort were recorded at predetermined elevations. Results: Task time was significantly longer in both trials for the LF group. Ratings of perceived exertion and thermal comfort were also significantly higher in the LF group, with three times more LF firefighters being unable to complete the ascent without sounding their low-air alarm. Conclusions: Higher CRF improves performance and efficiency during stair-climbing in simulated high-rise firefighting tasks. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effect of high-intensity, short-duration re-warm-up (RW) during half time (HT) on subsequent performance in a cold environment. Eleven male subjects (age, 21 ± 2 years; height, 172.4 ± 4.5 cm; body mass, 65.6 ± 7.1 kg; ...o2max, 47.5 ± 4.8 ml⋅kg-1⋅min-1) performed 2 experimental trials comprising 40 minutes of intermittent cycling exercise, which consisted of 15-second rest, 25-second unloading cycling, 10-second high-intensity cycling, and 70-second moderate-intensity cycling as the first half. In the second half, a cycling intermittent-sprint protocol (CISP) was performed, separated by a 15-minute HT period in cold conditions (5 °C, 50% relative humidity). Two experimental trials were included in a random order: (a) approximately 1 minute of high-intensity, short-duration RW (3 sets of 3-second maximal pedaling [body weight x 0.075 kp]) trial high-intensity intermittent cycling trials (HII); (b) 15 minutes of seated rest trial (CON). Cycling intermittent-sprint protocol consisted of 10 sets of a 2-minute exercise protocol, and each set consisted of 10-second rest, 5-second maximal pedaling (body weight x 0.075 kp), and 105-second active recovery at 50% maximum oxygen uptake (...o2max). Peak power output of 5-second maximal pedaling during CISP was higher in HII trials than in CON trials (HII: 807 ± 81 W, CON: 791 ± 78 W, p < 0.05). There was no significant difference in rectal temperature between trial types (p > 0.05). These results suggest that high-intensity, short-duration RW may be a useful HT strategy for improving subsequent performance in cold environments. [ABSTRACT FROM AUTHOR]

The placebo effect occurs when a desired outcome is experienced due to the belief that a treatment is effective, even in the absence of an active ingredient. One explanation for this effect is based on a person's expectations of a drug or supplement. Although caffeine's effects on sports performance have been studied, little is known about how expectations of caffeine affect neuromuscular fatigue during continuous muscle action. The physical working capacity at the fatigue threshold (PWCFT) can be used to assess neuromuscular fatigue noninvasively using surface electromyography. Thus, the purpose of this study was to investigate whether caffeine expectancy influences PWCFT. We hypothesized that regardless of expectancy, caffeine consumption would delay neuromuscular fatigue. The study involved 8 healthy college-aged men (mean ± SEM: age, 25.6 ± 1.0 years) who visited the laboratory on 4 occasions, each separated by 7 days. The subjects completed 4 experimental conditions, in random order, where they were told that they were consuming caffeine or placebo and either received caffeine or placebo. After consuming the drink, the subjects remained in the laboratory for an hour and then performed an incremental exercise test. The results showed that the condition where subjects were told that they were consuming caffeine and received caffeine had significantly higher mean values for maximal power output (F(3, 21) = 11.75; p < 0.001), PWCFT (F(3, 21) = 12.28; p < 0.001), PWCFT (%maximal power output; F(3, 21) = 8.75; p < 0.001), and heart rate at end exercise (%predicted; F(3, 21) = 3.83; p = 0.025) compared with the 2 conditions where placebo was received. However, no statistically significant mean differences were found from the condition where subjects were told that they were consuming placebo but consuming caffeine. This suggests that a person's expectancy and potential somatic response may serve as a cue for how an ergogenic aid or placebo could affect subsequent performance. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the effects of a child-specific school-based high-intensity interval training (HIIT) implemented into physical education (PE) classes on various hemodynamic parameters and heart rate variability indices. Forty-six students (age 11 ± 1 year) were randomized into an intervention (INT n = 22) and a control group (CON n = 24). During a 12-week period, the INT and CON groups participated in regular PE twice weekly (45-90 minutes). The INT group received HIIT during the first 20 minutes of the 2 PE classes. Systolic and diastolic blood pressure, total peripheral resistance, aortic pulse wave velocity (aPWV), heart rate, SD of normal to normal heartbeat intervals, the root mean square of successive differences between normal heartbeats (RMSSD), the proportion of differences between adjacent normal to normal heartbeat intervals of more than 50 ms, low-frequency power, high-frequency power, and the LF/HF ratio were assessed before and after the experimental period. A p value ≤0.05 was considered statistically significant. Forty students (20 INT; 20 CON) were included in the analysis. A significant time x group interaction was detected for aPWV(p = 0.05, η² = 0.099), RMSSD (p = 0.010, η² = 0.161), low-frequency power (p = 0.009, η² = 0.165), high-frequency power (p < 0.001, η² = 0.272), and the LF/HF ratio (p < 0.001, η² = 0.354). The INT group revealed significant improvements for the respective parameters. School-based HIIT can induce improvements in cardiovascular parameters. These results highlight the potential of embedding HIIT within the school setting, offering a time-efficient exercise intervention. [ABSTRACT FROM AUTHOR]

High-intensity interval training (HIIT) elicits similar and, in some cases, superior benefits vs. moderate-intensity continuous training (MICT). However, HIIT is typically more aversive than MICTbecause ofthe higher intensity and in turn, greater blood lactate accumulation (BLa). This study explored potential sex differences in perceptual responses to acute HIIT and sprint interval training. Fifteen men (age and ...O2max = 29 ± 8 years and 39 ± 3 ml⋅kg-1⋅min-1) and 13 women (age and ...O2max = 22 ± 2 years and 38 ± 5 ml⋅kg-1⋅min-1) who are healthy and recreationally active initially underwent testing of maximal oxygen uptake (...O2max) on a cycle ergometer. In randomized order on 3 separate occasions, they performed the 10 x 1-minute protocol at 85% of peak power output, 4 x 4-minute protocol at 85-95% maximal heart rate (%HRmax), or reduced exertion high intensity interval training consisting of 2 "all-out" 20-second sprints at a load equal to 5% body mass. Before and throughout each protocol, rating of perceived exertion (rating of perceived exertion [RPE] 6-20 scale), affective valence (+5 to -5 ofthe Feeling Scale), and BLa were assessed. Five minutes postexercise, enjoyment was measured using the Physical Activity Enjoyment scale survey. Results showed no difference in RPE(p = 0.17), affective valence (0.27), or enjoyment (p = 0.52) between men and women. Blood lactate accumulation increased in response to all protocols (p < 0.001), and men showed higher BLa than women (p = 0.03). Previous research suggests that interval exercise protocols are not interchangeable between men and women, yet our data reveal that men and women having similar ...O2max exhibit no differences in perceptual responses to interval exercise. [ABSTRACT FROM AUTHOR]

Background: The incidence of neonatal hyperbilirubinemia in Europe and the United States is estimated to be 3.2 and 4.4 per 10,000 live births, respectively. Abdominal massage for hyperbilirubinemia is considered a safe complementary treatment for infants that may increase number of defecations and decrease bilirubin levels. Purpose: This study was designed as a randomized controlled trial to determine the effect of abdominal massage on bilirubin levels in term infants receiving phototherapy. Methods: The sample consisted of 43 term newborns (intervention group: 23; control group: 20) who received phototherapy in a university hospital between June 2019 and February 2021. Information and observation forms were used for data collection. The intervention group received 6 abdominal massages over 2 days, performed 3 times a day, 6 hours apart, and lasting 5 minutes each. Results: Transcutaneous bilirubin levels and heart rate were significantly lower in the intervention group than in the control group at 48 hours (P = .015 and P = .033, respectively). Number of defecations was higher in the intervention group at 24 hours (P = .007) but there was no significant difference at 48 hours. The decrease in serum bilirubin between 24 and 48 hours was significantly greater in the intervention group (P = .005). Implication for Practice and Research: Abdominal massage was effective in reducing bilirubin levels and may increase the number of defecations. Providing massage training to the parents of infants who are discharged early could be a protective approach to prevent the rise in bilirubin levels. [ABSTRACT FROM AUTHOR]

Background: Skin-to-skin contact (SSC) is widely implemented in the neonatal intensive care unit (NICU) due to its established role in reducing mortality and morbidity. However, the impact of SSC on diaphragmatic electrical activity (Edi) in premature infants undergoing noninvasive pressure control (NIV-PC) for respiratory management remains insufficiently explored. Purpose: To assess the effects of SSC on Edi and vital signs in preterm infants managed with NIV-PC. Methods: A prospective, observational, crossover study was conducted, involving preterm infants admitted to a level III NICU between May 2020 and August 2021, who were receiving respiratory support with NIV-PC. Data were collected at 3 distinct time points: before SSC (pre-SSC period), during SSC (SSC period), and after SSC (post-SSC period). Thirty-minute periods of stable data were extracted for analysis. Results: A total of 21 SSC sessions were performed on 14 preterm infants, with a median age at the initiation of SSC of 62 days. The median (interquartile range) Edi peak (in microvolts) before, during, and after SSC was 7.1 (5.8-10.8), 6.8 (4.3-8.8), and 7.1 (5.5-8.8), respectively. No statistically significant differences were observed in Edi peak or minimum values during SSC, when compared with the periods before and after the SSC procedure. Likewise, no significant changes were noted in respiratory rate, oxygen saturation, heart rate, or the incidence of apnea. Implications for Practice and Research: SSC in preterm infants undergoing NIV-PC does not exacerbate their clinical condition. Further investigations involving diverse patient cohorts are warranted. [ABSTRACT FROM AUTHOR]

Within the initial minutes of square-wave exercise transitions above the moderate-intensity domain, the reliance on the anaerobic energy sources may induce some levels of metabolic instability; however, no study has attempted to limit metabolic instability at exercise onset by manipulating the exercise transition phase to a target work rate (WR). Purpose: This study aimed to investigate whether a ramp-to-constant WR (rCWR) transition compared with a square-wave-to-constant WR (CWR) transition within the heavy-intensity domain can reduce metabolic instability and decrease the oxygen cost of exercise. Methods: Fourteen individuals performed (i) a ramp-incremental test to task failure, (ii) a 21-min CWR within the heavy-intensity domain, and (iii) an rCWR to the same WR. Oxygen uptake (...O2), lactate concentration ([La-]), and muscle oxygen saturation (SmO2) were measured. ...O2 and ...O2 gain (...O2-G) during the first 10-min steady-state ...O2 were analyzed. [La-] before, at, and after steady-state ...O2 and SmO2 during the entire 21-min steady-state exercise were also examined. Results: ...O2 and ...O2-G during rCWR (2.49 ± 0.58 L⋅min-1 and 10.7 ± 0.2 mL⋅min-1⋅W-1, respectively) were lower (P < 0.001) than CWR (2.57 ± 0.60 L⋅min-1 and 11.3 ± 0.2 mL⋅min-1⋅W-1, respectively). [La-] before and at steady-state ...O2 during the rCWR condition (1.94 ± 0.60 and 3.52 ± 1.19 mM, respectively) was lower than the CWR condition (3.05 ± 0.82 and 4.15 ± 1.25 mM, respectively) (P <0.001). [La-] dynamics after steady-state ...O2 were unstable for the rCWR (P = 0.011). SmO2 was unstable within the CWR condition from minutes 4 to 13 (P <0.05). Conclusions: The metabolic disruption caused by the initial minutes of square-wave exercise transitions is a primary contributor to metabolic instability, leading to an increased ...O2-G compared with the rCWR condition approach. The reduced early reliance on anaerobic energy sources during the rCWR condition may be responsible for the lower ...O2-G. [ABSTRACT FROM AUTHOR]

Purpose: Sedentary behavior may contribute to increased central wave reflection due to associated peripheral vasoconstriction, yet its impact on central hemodynamics and the mitigating effects of interventional strategies have not been thoroughly investigated. We tested whether standing or seated elliptical breaks alleviate the deleterious effects of prolonged sitting on central wave reflections. Methods: Eighteen healthy adults (9 9 females, 25 ± 3 yr) completed three 3-h protocols on separate days: uninterrupted sitting, sitting with periodic standing, and sitting with periodic seated elliptical activity. Central wave reflection, central pulse wave velocity, and lower-limb pulse wave velocity were measured before and after each intervention. Results: Central relative wave reflection magnitude (RM) increased during sitting (0.31 ± 0.05 to 0.35 ± 0.05; P <0.01) but did not change after standing (0.30 ± 0.05 to 0.32 ± 0.04; P = 0.19) or elliptical protocols (0.30 ± 0.05 to 0.30 ± 0.04; P > 0.99). The change in RM during prolonged sitting (ARM) was attenuated with elliptical activity (0.04 ± 0.05 vs 0.00 ± 0.03; P = 0.02) but not with periodic standing (0.04 ± 0.04 vs 0.02 ± 0.05; P = 0.54). In addition, augmentation index and central pulse wave velocity increased after sitting (both P < 0.01) and periodic standing (both P < 0.01) but were unchanged after elliptical activity. Lower limb pulse wave velocity did not change after sitting (P = 0.73) or standing (P = 0.21) but did decrease after elliptical activity (P = 0.03). Conclusions: Prolonged sitting without interruptions increased central wave reflection, whereas elliptical but not standing interruptions were able to ameliorate multiple sitting-induced vascular consequences. More work is required to examine the long-term effectiveness of interruption strategies, as well as the optimal type, frequency, and duration for reducing vascular risk associated with sedentary behaviors. [ABSTRACT FROM AUTHOR]

Purpose: This study quantified the metabolic demands (oxygen uptake (...O2)), power output adjustments, changes in the ...O2/power output ratio, and perceptual responses (rating of perceived exertion (RPE)) during constant heart rate (HR) exercise performed within the vigorous intensity range (77%-95% HRpeak). Methods: Twelve women (mean ± SD age, 22 ± 4 yr) performed a graded exercise test to exhaustion to determine peak parameters, and three randomly ordered, constant HR trials to exhaustion or for 60 min at the lower (HRL = 77% HRpeak), middle (HRM = 86% HRpeak), and higher (HRH = 95% HRpeak) end of the vigorous intensity range. Time course of changes and patterns of responses were examined for ...O2, power output, ...O2/power output, and RPE for the composite and for each subject. Results: Across the HRL (time to exhaustion (Tlim) = 56.3 ± 9.9 min), HRM (51.8 ± 13.5 min), and HRH (27.2 ± 17.7 min) trials, ...O2 and power output decreased quadratically (P < 0.05) relative to the initial value from 10% to 100% of Tlim, whereas the ...O2/power output increased quadratically from 20% to 100% Tlim and RPE increased linearly from 50% to 100% Tlim. The ...O2 and RPE, collapsed across time, for HRL (54.3% ±3.3% ...O2peak, 11 ± 1.5 RPE) were lower than HRM (64.9% ± 4.5% ...O2peak, 14 ± 1.7 RPE), and both were lower than HRH (80.1% ± 4.1% ...O2peak, 17 ± 1.4 RPE). None of the 12 subjects at HRL, 6 at HRM, and 7 at HRH were within the vigorous ...O2 range. Conclusions: The HRL was not sufficient to meet the desired metabolic intensity for vigorous exercise, whereas the middle to higher end of the range elicited a ...O2 within the prescribed range of only ~50%-60% of the subjects. This study indicated that exercise held constant at a percentage of HRpeak cannot consistently be used to prescribe a desired metabolic stimulus. [ABSTRACT FROM AUTHOR]

Background: Aerobic exercise facilitates postconcussion symptom resolution at the group level, but patient-level characteristics may affect the likelihood of treatment efficacy. Purpose: This study aimed to investigate demographic and clinical characteristics, which differentiate postconcussion aerobic exercise treatment efficacy from nonefficacy in the intervention arm of a randomized clinical trial. Methods: Adolescent and young adult participants initiated a standardized aerobic exercise intervention within 14 d of concussion, consisting of self-selected exercise for 100 min⋅wk-1 at an individualized heart rate (80% of heart rate induced symptom exacerbation during graded exercise testing). Treatment efficacy was defined as symptom resolution within 28-d postconcussion. Treatment efficacy and nonefficacy groups were compared on demographics, clinical characteristics, intervention adherence, and persistent symptom risk using the Predicting Persistent Postconcussive Problems in Pediatrics (5P) clinical risk score. Results: A total of 27 participants (16.1 ± 2.3 yr old; range, 11-21 yr; 52% female) began the intervention, with a mean of 9.5 ± 3.7 d after concussion; half (n = 13; 48%) demonstrated treatment efficacy (symptom resolution within 28 d postconcussion). Those whose symptoms resolved within 28 d had significantly lower preintervention postconcussion symptom inventory scores (21.2 ± 13.2 vs 41.4 ± 22.2; P < 0.01), greater adherence to the intervention (77% vs 36%; P = 0.05), and longer average exercise duration (median [interquartile range], 49.7 [36.8-68.6] vs 30.4 [20.7-34.7] min; P < 0.01) than those whose symptoms lasted more than 28 d. Groups were similar in age, sex, timing of intervention, and preintervention 5P risk score. Conclusions: A standardized aerobic exercise intervention initiated within 14 d of concussion demonstrated efficacy for approximately half of participants, according to our definition of treatment efficacy. This multisite aerobic exercise intervention suggests that lower symptom severity, higher intervention adherence, and greater exercise duration are factors that increase the likelihood of symptoms resolving within 28 d of concussion. [ABSTRACT FROM AUTHOR]

Objective: To evaluate sleep deprivation effects on the acute physiological response to a combined stressor of woodsmoke and exercise. Methods: Ten participants completed two exercise trials (8 hours of sleep vs 4 hours) with woodsmoke. Trials were conducted in a crossover design. Key measures examined before and after each trial included heart rate variability, pulse wave velocity, blood pressure, pulmonary function testing, and oxidative stress. Results: Acute sleep deprivation experienced before exercise and woodsmoke exposure did not impact metrics of heart rate variability, pulse wave velocity, pulmonary function testing, blood pressure, or oxidative stress. Conclusions: Acute sleep deprivation did not amplify physiologic metrics in response to moderate-intensity aerobic exercise with inhaled woodsmoke. Although findings do not eliminate the negative impacts of inhaling woodsmoke, more research is needed to understand the acute effects of woodsmoke exposure on the cardiovascular system. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the effect of an 8-week swimming training program on biomechanical and physiological responses during a swim-to-cycle simulation. Fifteen triathletes were randomly allocated to 3 groups: a 6-beat-kick group (K6), a 4-beat-kick group (K4), and a control group (CG). Biomechanical and physiological parameters were evaluated during a 400-m swim and a 10-minute cycle segment before (Pretraining) and after (Posttraining) the program. A lower stroke frequency (p = 0.004) and a higher stroke length (p = 0.002) was found in K6 compared with CG at Posttraining. A reduction in the K6 emerged between Pretraining and Posttraining during cycling for heart rate (p = 0.005), ... (p = 0.014), and energy expenditure (p = 0.008). A positive association emerged between swim kick index and cycling cadence in the K6 group. The improvement in stroke frequency and length observed in the K6 group could be explained as an improvement in swimming technique. Similarly, the reduction in energy expenditure during cycling at Posttraining for the K6 group suggests an improvement in the working economy. Triathlon coaches and athletes should consider the inclusion of high swim kick into their training programs to enhance swim and cycling performance, which can ultimately lead to an improvement in the swim-to-cycle transition and the overall triathlon performance. [ABSTRACT FROM AUTHOR]

OBJECTIVES: Systemic thrombolysis improves outcomes in patients with pulmonary embolism (PE) but is associated with the risk of hemorrhage. The data on efficacy and safety of reduced-dose alteplase are limited. The study objective was to compare the characteristics, outcomes, and complications of patients with PE treated with full- or reduced-dose alteplase regimens. DESIGN: Multicenter retrospective observational study. SETTING: Tertiary care hospital and 15 community and academic centers of a large healthcare system. PATIENTS: Hospitalized patients with PE treated with systemic alteplase. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Pre- and post-alteplase hemodynamic and respiratory variables, patient outcomes, and complications were compared. Propensity score (PS) weighting was used to adjust for imbalances of baseline characteristics between reduced- and full-dose patients. Separate analyses were performed using the unweighted and weighted cohorts. Ninety-eight patients were treated with full-dose (100 mg) and 186 with reduced-dose (50 mg) regimens. Following alteplase, significant improvements in shock index, blood pressure, heart rate, respiratory rate, and supplemental oxygen requirements were observed in both groups. Hemorrhagic complications were lower with the reduced-dose compared with the full-dose regimen (13% vs. 24.5%, p = 0.014), and most were minor. Major extracranial hemorrhage occurred in 1.1% versus 6.1%, respectively (p = 0.022). Complications were associated with supratherapeutic levels of heparin anticoagulation in 37.5% of cases and invasive procedures in 31.3% of cases. The differences in complications persisted after PS weighting (15.4% vs. 24.7%, p = 0.12 and 1.3% vs. 7.1%, p = 0.067), but did not reach statistical significance. There were no significant differences in mortality, discharge destination, ICU or hospital length of stay, or readmission after PS weighting. CONCLUSIONS: In a retrospective, PS-weighted observational study, when compared with the full-dose, reduced-dose alteplase results in similar outcomes but fewer hemorrhagic complications. Avoidance of excessive levels of anticoagulation or invasive procedures should be considered to further reduce complications. [ABSTRACT FROM AUTHOR]

Basketball is a dynamic sport, requiring athletes to elicit a high-level of physical, tactical, technical, and psychological attributes and athletes must possess a robustly trained aerobic energy system. There is no research to assess how objectively measured training loads throughout a season influence aerobic capacity. The following study was a retrospective analysis of an NCAA Division I women's basketball team throughout a 5-month (23-week) competitive season. Data were sorted into season half totals and maximal oxygen consumption was recorded before, at the midway point and within 1-week postseason. Twelve athletes were monitored during each practice, pregame shoot around, scrimmage, and game for a total of 1,378 recorded sessions with a valid heart rate-based wearable microsensor (Polar Team Pro) during the season. There was a main effect of time for ...O2max throughout the season (p < 0.001). Post hoc analysis revealed there was a significant increase in ...O2max from preseason to postseason (p < 0.001). Interestingly, there were significant (p ≤ 0.001 for all) decreases from the first half to the second half of the season for training load, and time allocated to HRZone1-4, but no difference in time for the most intense zone, HRzone5. Conclusion: Oxygen consumption significantly increased 7.5% from preseason to postseason despite a reduction in overall work. The only training intensity that was not different from the first half to second half of the season was time in the highest heart rate intensity zone ≥85% of HRmax. [ABSTRACT FROM AUTHOR]

The aims of this study were to evaluate the (a) relationships between daily physical demands and nighttime sleep, heart rate (HR), and heart rate variability (HRV); (b) weekly changes in physical demands and sleep; and (c) differences among positions and between training and competition during a competitive season in National Collegiate Athletic Association (NCAA) women's ice hockey. Twenty-five NCAA Division I women's ice hockey athletes wore a sensor at night to monitor sleep quantity or quality (e.g., time asleep and sleep efficiency) and physiology (e.g., HR and HRV). During training and competitions (31 regular season and 7 postseason), athletes wore performance monitoring systems to assess workload demands (e.g., training impulse and TRIMP). As internal workload (TRIMP, Time >80% of HRmax, Average HR) during training or competition increased, nocturnal HRV decreased, HR increased, and Sleep Duration, Sleep Score, and Readiness Score decreased that night. Across the season, athletes experienced lower HRV, but exhibited longer sleep durations. Training Distance, Duration, Time >80% HRmax, Average HR, and TRIMP decreased, whereas competition Total Distance, Duration, and TRIMP increased across weeks throughout the season. There were differences across positions and season blocks when evaluating these data at the mesocycle level. Athletes slept longer before competition compared with training, but physiological data did not differ. Competitions had greater physiological demands than training. We speculate that the increased focus on sleep hygiene, as evidenced by the increase in sleep over the season, may have served as a recovery aid to combat physiological stress of accumulated demands of competitions that increased over time into postseason tournaments. [ABSTRACT FROM AUTHOR]

Pain sensitivity of healthy subjects in the cold-pressor (CP) test was proposed to be dichotomously distributed and to represent a pain sensitivity trait. Still, it has not been systematically explored which factors influence this pain sensitivity readout. The aim of this study was to distinguish potential contributions of local tissue-related factors such as perfusion and thermoregulation or gain settings in nociceptive systems. Cold-pressor–sensitive and CP-insensitive students screened from a medical student laboratory course were recruited for a CP retest with additional cardiovascular and bilateral local vascular monitoring. In addition, comprehensive quantitative sensory testing according to Deutscher Forschungsverbund Neuropathischer Schmerz standards and a sustained pinch test were performed. Cold pressor was reproducible across sessions (Cohen kappa 0.61 ± 0.14, P < 0.005). At 30 seconds in ice water, CP-sensitive subjects exhibited not only more pain (78.6 ± 26.3 vs 29.5 ± 17.5, P < 0.0001) but also significantly stronger increases in mean arterial blood pressure (12.6 ± 9.3 vs 5.6 ± 8.1 mm Hg, P < 0.05) and heart rate (15.0 ± 8.2 vs 7.1 ± 6.2 bpm, P < 0.005), and lower baroreflex sensitivity, but not local or vasoconstrictor reflex–mediated microcirculatory responses. Cold-pressor–sensitive subjects exhibited significantly lower pain thresholds also for cold, heat, and blunt pressure, and enhanced pain summation, but no significant differences in Aδ-nociceptor–mediated punctate mechanical pain. In conclusion, differences in nociceptive signal processing drove systemic cardiovascular responses. Baroreceptor activation suppressed pain and cardiovascular responses more efficiently in CP-insensitive subjects. Cold-pressor sensitivity generalized to a pain trait of C-fiber–mediated nociceptive channels, which was independent of local thermal and vascular changes in the ice-water–exposed hand. Thus, the C-fiber pain trait reflects gain setting of the nociceptive system. [ABSTRACT FROM AUTHOR]

Objective: The aim of the study is to thoroughly describe exercise programs that were performed during a firefighter training academy, including their effects on body composition and physical fitness. Methods: Fourteen recruits performed exercise programs during a 24-week training academy and several components of their body composition and physical fitness were measured. Moreover, their heart rate (HR) and session rating of perceived exertion (sRPE) were recorded during and after every training session, respectively. Results: Fat-free mass, subcutaneous fat in the abdomen, cardiovascular fitness, flexibility, lower-body power, and muscular endurance significantly improved during the study (P ≤ 0.05). The highest HR and sRPE responses were observed during aerobic training (AT) sessions. The average HR responses relative to maximum HR were similar during AT, high-intensity circuit training, multimodal high-intensity interval training, and high-intensity functional training; however, the sRPEs during high-intensity circuit training and multimodal high-intensity interval training were significantly lower than AT. Conclusions: Several effective exercise programs can be implemented during firefighter training academies. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to characterize both the efficacy of altered restriction pressures and consequences of optimized blood flow restriction (BFR) for altering the cardiovascular and fluid regulating response in humans. Methods: This work comprised a series of related trials. Phase 1: during semi-recumbent cycling (5 min, 60 W) with BFR at 0%, 50%, 75%, 100%, and 125% of participants' lowest arterial occlusion pressure (LOP) echocardiographic images were collected alongside continuous heart rate (HR) and blood pressure (BP). In phase 2, 24 h fluid balance (intake-output) and fluid-regulating hormone responses were measured after a practical BFR exercise session (treadmill walking: 5·3 min, 1 min rest, 5 km·h−1, 5% incline, 100% LOP). Phase 3 examined the magnitude and effect of blood volume distribution following BFR treadmill walking using a modified CO-rebreathe technique. Results: Cardiac ejection fraction remained stable irrespective of cuff pressure and despite a reduction in end-diastolic volume (Δ of 11 ± 9 mL, P = 0.02). HR and BP were highest at 100% LOP (ΔHR = 18 ± 19 bpm, ΔSBP = 51 ± 30 mm Hg, ΔDBP = 33 ± 15 mm Hg, ΔRate Pressure Product = 76 ± 32 bpm·mm Hg·100−1). BFR treadmill walking stimulated a greater release of fluid-regulating hormones than normal walking (Δrenin = BFR: 25.3 ± 24.2 vs CON: 9.1 ± 11.8 ng·L−1; Δcopeptin = BFR: 50.1 ± 97.9 vs. CON: 0.43 ± 0.8 pmol·L−1), but no difference in fluid retention was observed (P = 0.2). Approximately 27% of total blood volume was confined to the legs during BFR, but the relative volume trapped in the legs was not related to fluid-regulating hormone release (renin r = −0.04, P = 0.9; copeptin r = 0.27, P = 0.3). Conclusions: BFR exercise elicits the largest cardiovascular effect using 100% LOP, with evidence of appreciable fluid regulating hormonal response during a typical BFR exercise session. The relative volume of blood sequestered in the limb does not appear to drive this response. [ABSTRACT FROM AUTHOR]

Purpose: Although caffeine is known to possess ergogenic effects, previous studies demonstrated no effect of caffeine on 800-m run performance outdoors, which might be due to several uncontrolled factors including pacing strategies. We hypothesized that caffeine ingestion improves a pace-controlled simulated 800-m run performance. We also hypothesized that exercise-induced arterial hypoxemia occurs during the simulated 800-m run, and this response is mitigated by caffeine-induced increases in exercise ventilation. Methods: In a randomized, double-blind, placebo-controlled and crossover design, 16 (3 females) college middle-distance runners who have 800-m seasonal best of 119.97 ± 7.64 s ingested either 1) placebo (6 mg of glucose per kilogram of body weight) or caffeine (6 mg of caffeine per kilogram of body weight). Then they performed an 800-m run consisting of 30-s running at 103% of their 800-m seasonal best, followed by running at 98% of seasonal best until exhaustion, which mimics actual 800-m run pacing pattern. Results: Running time to exhaustion was extended by 7.3% ± 6.2% in the caffeine-ingested relative to placebo trial (123 ± 12 vs 114 ± 9 s, P = 0.04). Arterial oxygen saturation markedly decreased during the simulating running, but this response was similar (76.6% ± 5.7% vs 81.1% ± 5.2%, at 113 s of the simulating running) between the caffeine and placebo trials (P ≥ 0.23 for time–supplement interaction and main effect of supplement). Minute ventilation, oxygen uptake (all P ≥ 0.36 for time–supplement interaction and main effect of supplement), and rate of perceived exertion (all P ≥ 0.11) did not differ between the trials throughout the simulating running. Heart rate was higher in the caffeine-ingested trial throughout the simulated running (P < 0.01 for main effect of supplement). Postexercise blood lactate concentration was higher in the caffeine trial (P = 0.02). Conclusions: Caffeine ingestion improves simulated 800-m run performance without affecting exercise ventilation and severe exercise-induced arterial hypoxemia. [ABSTRACT FROM AUTHOR]

Introduction: The aim of this study was to compare vastus lateralis (VL) and rectus femoris (RF) muscles for their nervous and mechanical adaptations during two bouts of downhill walking (DW) with load carriage performed 2 wk apart. Moreover, we investigated cardiometabolic and perceived exertion responses during both DW bouts. Methods: Seventeen participants performed two 45-min sessions of loaded DW (30% of body mass; slope, −25%; speed, 4.5 km·h−1) separated by 2 wk. Rating of perceived exertion, cost of walking, heart rate, and EMG activity of thigh muscles were assessed during the DW. Muscle shear elastic modulus (μ) of RF and VL were assessed before each exercise bout. Maximal voluntary contraction torque was assessed before (PRE), immediately after (POST), and 24 and 48 h after the two exercise bouts. Results: Maximal voluntary contraction torque decreased from POST (−23.7% ± 9.2%) to 48 h (−19.2% ± 11.9%) after the first exercise (Ex1), whereas it was significantly reduced only at POST (−14.6% ± 11.0%) after the second exercise (Ex2; P < 0.001). Rating of perceived exertion (Ex1: 12.3 ± 1.9; Ex2: 10.8 ± 2.0), heart rate (Ex1: 156 ± 23 bpm; Ex2: 145 ± 25 bpm), cost of walking (Ex1: 4.5 ± 0.9 J·m−1·kg−1; Ex2: 4.1 ± 0.7 J·m−1·kg−1), and RF EMG activity (Ex1: 0.071 ± 0.028 mV; Ex2: 0.041 ± 0.014 mV) were significantly decreased during Ex2 compared with Ex1 (P < 0.01). RF μ was significantly greater in Ex2 (0.44 ± 0.18) compared with Ex1 (0.56 ± 0.27; P < 0.001). Conclusions: The RF muscle displayed specific mechanical and nervous adaptations to repeated DW bouts as compared with VL. Moreover, the muscle adaptations conferred by the first bout of DW could have induced greater exercise efficiency, inducing lesser perceived exertion and cardiometabolic demand when the same exercise was repeated 2 wk later. [ABSTRACT FROM AUTHOR]

Purpose: The kinetics of physiological responses to exercise have traditionally been characterized by estimating exponential equation parameters using iterative best-fit techniques of heart rate (HR) and gas exchange (respiratory rate, oxygen uptake (V̇O2), carbon dioxide output, and ventilation). In this study, we present a novel approach to characterizing the maturation of physiological responses to exercise in children by accounting for response uncertainty and variability. Methods: Thirty-seven early-pubertal (17 females, 20 males) and 44 late-pubertal (25 females, 19 males) participants performed three multiple brief exercise bouts (MBEB). MBEB consisted of ten 2-min bouts of cycle ergometry at constant work rate interspersed by 1-min rest. Exercise intensity was categorized as low, moderate, or high, corresponding to 40%, 60%, and 80% of peak work rate, and performed in random order on 3 separate days. We evaluated sample entropy (SampEn), approximate entropy, detrended fluctuation analysis, and average absolute local variability of HR and gas exchange. Results: SampEn of HR and gas-exchange responses to MBEB was greater in early- compared with late-pubertal participants (e.g., V̇O2 early-pubertal vs late-pubertal, 1.70 ± 0.023 vs 1.41 ± 0.027; P = 2.97 × 10−14), and decreased as MBEB intensity increased (e.g., 0.37 ± 0.01 HR for low-intensity compared with 0.21 ± 0.014 for high intensity, P = 3.56 × 10−17). Females tended to have higher SampEn than males (e.g., 1.61 ± 0.025 V̇O2 for females vs 1.46 ± 0.031 for males, P = 1.28 × 10−4). Average absolute local variability was higher in younger participants for both gas exchange and HR (e.g., early-pubertal vs late-pubertal V̇O2, 17.48 % ± 0.56% vs 10.24 % ± 0.34%; P = 1.18 × 10−21). Conclusions: The greater entropy in signal response to a known, quantifiable exercise perturbation in the younger children might represent maturation-dependent, enhanced competition among physiological controlling mechanisms that originate at the autonomic, subconscious, and cognitive levels. [ABSTRACT FROM AUTHOR]