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This study investigated the test–retest reliability of running economy (RE) and metabolic and cardiorespiratory parameters related to endurance running performance using a multistage incremental treadmill test. On two occasions separated by 21–28 days, 12 male middle- and long-distance runners ran at 10, 11, 12, 13, and 14 km/hr for 8 min each stage, immediately followed by a ramp test to volitional exhaustion. Carbohydrate (10% maltodextrin solution) was consumed before and during the test to provide ∼1 g/min of exercise. RE, minute ventilation ( V ˙ E), oxygen consumption ( V ˙ O 2 ), carbon dioxide production ( V ˙ CO 2 ), respiratory exchange ratio (RER), heart rate (HR), ratings of perceived exertion (RPE), and blood glucose and lactate concentrations were recorded for each stage and at volitional exhaustion. Time-to-exhaustion (TTE) and peak oxygen consumption ( V ˙ O 2 peak) during the ramp test were also recorded. Absolute reliability, calculated as the coefficient of variation (CV) between repeated measures, ranged from 2.3% to 3.1% for RE, whereas relative reliability, calculated as the intraclass correlation coefficient (ICC), ranged from.42 to.79. V ˙ E , V ˙ O 2 , V ˙ O 2 peak , V ˙ CO 2 , RER, and HR had a CV of 1.1%–4.3% across all stages. TTE and RPE had a CV of 7.2% and 2.3%–10.8%, respectively, while glucose and lactate had a CV of 4.0%–17.8%. All other parameters, except for blood glucose, were demonstrated to have good-to-excellent relative reliability assessed by ICC. Measures of RE, V ˙ O 2 peak , and TTE were reliable during this two-phase multistage incremental treadmill test in a cohort of trained and highly trained male middle- and long-distance runners. [ABSTRACT FROM AUTHOR]

Purpose: The study examined the longitudinal interplay of anthropometric, metabolic, and neuromuscular development related to performance in adolescent national-level swimmers over 12 months. Methods: Seven male and 12 female swimmers (14.8 [1.3] y, FINA [International Swimming Federation] points 716 [51]) were tested before (T0) and after the preparation period (T1), at the season's peak (T2), and before the next season (T3). Anthropometric (eg, fat percentage) and neuromuscular parameters (squat and bench-press load-velocity profile) were assessed on dry land. Metabolic (cost of swimming [C], maximal oxygen uptake [ V ˙ O 2 peak ], and peak blood lactate [bLapeak]) and performance (sprinting speed [vsprint] and lactate thresholds [LT1 and 2]) factors were determined using a 500-m submaximal, 200-m all-out, 20-second sprint, and incremental test (+0.03 m·s−1, 3 min), respectively, in front-crawl swimming. Results: vsprint (+0.6%) and LT1 and 2 (+1.9–2.4%) increased trivially and slightly, respectively, from T0 to T2 following small to moderate strength increases (≥+10.2%) from T0 to T1 and V ˙ O 2 peak (+6.0%) from T1 to T2. Bench-press maximal strength and peak power correlated with vsprint from T0 to T2 (r ≥.54, P <.05) and LT2 at T1 (r ≥.47, P <.05). Changes in fat percentage and V ˙ O 2 peak (T2–T1 and T3–T2, r ≤ −.67, P <.01) and C and LT2 (T2–T0, r = −.52, P =.047) were also correlated. Conclusions: Increases in strength and V ˙ O 2 peak from preparation to the competition period resulted in improved sprint and endurance performance. Across the season, upper-body strength was associated with vsprint and LT2, although their changes were unrelated. [ABSTRACT FROM AUTHOR]

Purpose: To identify differences in heart rate (HR) and concentration of blood lactate ([La]) relationships between laboratory- and field-based skate-roller-skiing tests. Methods: Fourteen world-class biathletes (8 women, 6 men) completed a laboratory- and field-based roller-skiing test using the skate technique. The laboratory-based test comprised 5 to 7 submaximal steps at a fixed incline and speed on a roller-skiing treadmill. The field-based test comprised 5 steps on a course where the final hill was designed to mimic the conditions of the laboratory test. HR and [La] were measured for each step. The HR associated with 2 mmol·L−1 (HR@2 mmol) and 4 mmol·L−1 (HR@4 mmol) of [La] was calculated using an interpolation method. A 1-way analysis of variance and Bland–Altman analyses with 95% limits of agreement (LoA) were used to determine if test type influenced HR@2 mmol or HR@4 mmol. A second-order polynomial was fitted to group-level data to highlight the HR–[La] relationships for laboratory- and field-based tests. Results: HR@2 mmol was lower for field tests than for laboratory tests (mean bias: 1.9%HRmax; 95% LoA: −4.5 to +8.3%HRmax; P <.001). HR@4 mmol was also lower for field tests compared to laboratory tests (mean bias: 2.4%HRmax; 95% LoA: −1.2 to +6.0%HRmax; P <.001). On the group level, the lactate threshold occurred at a lower HR during roller skiing in the field compared to the laboratory. Conclusions: The findings from this study confirm that for a given HR, [La] was greater in field- compared with laboratory-based conditions. These results might have implications for how coaches define training-intensity "zones" during skate roller skiing based on laboratory tests. [ABSTRACT FROM AUTHOR]

Blood lactate concentration during exercise is a reliable indicator of energy metabolism and endurance performance. Lactate is also present in sweat, and sweating plays an important role in thermoregulation, especially in hot conditions. Recently, wearable sensors have enabled the real-time and noninvasive measurement of sweat lactate concentration, potentially serving as an alternative indicator of blood lactate response. However, the evidence regarding the relationship between sweat and blood lactate responses during incremental exercise in hot conditions is lacking. In a randomized cross-over design, six highly trained male runners completed two incremental treadmill tests under normal (20°C/50%RH) or hot (30°C/50%RH) conditions. The tests include 3-min running stages and 1-min recovery, starting at 12 km/h and increasing by 1 km/h at each stage. Blood and sweat lactate concentrations were measured at each stage to determine blood and sweat lactate thresholds (LT). Blood lactate concentrations were higher under hot conditions (p < 0.01), but there was no difference in the response pattern or velocity at blood LT between conditions. Significant early increase (p < 0.01) in sweat lactate and low velocity at sweat LT (p < 0.05) were observed under hot conditions. A significant correlation between blood and sweat lactate concentrations was found under normal conditions (p < 0.001) but not under hot conditions, and no significant correlations were observed between the velocity at blood and sweat LT. In conclusion, sweat lactate concentration does not consistently reflect blood lactate concentration during incremental exercise. [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]

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]

Background: This study aimed to investigate the effectiveness of a 6‐month home‐based high‐intensity interval training (HIIT) intervention to improve peak oxygen consumption (V̇O2peak) and lactate threshold (LT) in older adults. Methods: Two hundred thirty‐three healthy older adults (60–84 years; 54% females) were randomly assigned to either 6‐month, thrice‐weekly home‐based HIIT (once‐weekly circuit training and twice‐weekly interval training) or a passive control group. Exercise sessions were monitored using a Polar watch and a logbook for objective and subjective data, respectively, and guided by a personal coach. The outcomes were assessed using a modified Balke protocol combining V̇O2peak and LT measures. General linear regression models assessed between‐group differences in change and within‐group changes for each outcome. Results: There was a significant between‐group difference in the pre‐to‐post change in V̇O2peak (difference: 1.8 [1.2; 2.3] mL/kg/min; exercise: +1.4 [1.0; 1.7] mL/kg/min [~5%]; control: −0.4 [−0.8; −0.0] mL/kg/min [approximately −1.5%]; effect size [ES]: 0.35). Compared with controls, the exercise group had lower blood lactate concentration (−0.7 [−0.9; −0.4] mmol/L, ES: 0.61), % of peak heart rate (−4.4 [−5.7; −3.0], ES: 0.64), and % of V̇O2peak (−4.5 [−6.1; −2.9], ES: 0.60) at the intensity corresponding to preintervention LT and achieved a higher treadmill stage (% incline) at LT (0.6 [0.3; 0.8]; ES: 0.47), following the intervention. Conclusion: This study highlights the effectiveness of a home‐based HIIT intervention as an accessible and equipment‐minimal strategy to induce clinically meaningful improvements in cardiorespiratory fitness in older adults. Over 6 months, the exercise group showed larger improvements in all outcomes compared with the control group. Notably, the LT outcome exhibited a more pronounced magnitude of change than V̇O2peak. [ABSTRACT FROM AUTHOR]

Purpose: Oxygen uptake kinetics (VO2kinetics) is a measure of an athlete's capacity to respond to variations in energy demands. Faster VO2kinetics is associated with better performance in endurance sports, but optimal training methods to improve VO2kinetics remain unclear. This study compared the effects of 2 high-intensity interval-training (HIIT) programs on traditional rowing performance and VO2kinetics. Methods: Twelve highly trained rowers performed one of two 6-week HIIT protocols: either 3-minute repetitions at 90% (HIIT90; n = 5) of peak aerobic power (PAP) or 90-second repetitions at 100% (HIIT100; n = 7) of PAP. Before (PRE) and after (POST) the training intervention, they performed an incremental test to exhaustion to determine the individual lactate threshold, onset of blood lactate accumulation and PAP, and two 6-minute rest-to-exercise transitions to determine VO2kinetics. Results: No significant changes (P >.05) were observed for rowing ergometer power output at individual lactate threshold (HIIT90 PRE 255 [12], POST 264 [13]; HIIT100 247 [24], 266 [28] W), onset of blood lactate accumulation (279 [12], 291 [16]; 269 [23], 284 [32] W), or PAP (359 [13], 381 [15]; 351 [21], 363 [29] W) or for any parameters of VO2kinetics. No differences were observed between HIIT interventions. Conclusion: The HIIT interventions did not induce significant performance or VO2kinetics improvements, although mean power output at individual lactate threshold, onset of blood lactate accumulation, and PAP increased by 5.7%, 5.0%, and 4.5%, respectively. This suggests that the exact intensity and duration of HIIT sessions performed in the same intensity domain may be of lesser importance than other well-established influential factors (eg, training volume progression, training intensity distribution, altitude training) to develop aerobic qualities in endurance athletes. [ABSTRACT FROM AUTHOR]

The underwater phase (UP) is highly important for overall swimming performance in most swimming events. However, the metabolic effects of the prolonged UP remain unclear. The purpose of this cross-sectional study was to compare the blood lactate response to submaximal front-crawl swimming with short and extended UP. Twelve (four females) junior competitive swimmers (aged 15.4 (1.4) years) undertook 200 m front-crawl swim trials in a 25 m pool at a pre-determined "anaerobic threshold" velocity on two occasions using short (<5 m) and extended (12.5 m) UP after each turn. Pacing and total time were ensured to be identical between the trials. Capillary blood lactate response was measured. Testing for 25 m swim time with <5 m and 12.5 m UP was conducted on a separate occasion. When athletes undertook and extended UP after each propulsion from the wall, their post-exercise blood lactate concentration reached 7.9 (2.1) mmol/L, more than two times higher than the response to trial with short UP (p < 0.001). All-out 25 m swimming with <5 m or 12.5 m UP disclosed no difference in locomotion velocity (p > 0.05). In conclusion, extending UP of submaximal front-crawl swimming close to maximally allowed during the races substantially increases blood lactate accumulation, i.e., increases the reliance on anaerobic metabolism. Therefore, extended UP is most likely counterproductive for the performance in long-distance swimming, at least for the athletes with a FINA score of <800. On the other hand, the extension of UP could be an effective strategy to train 'lactate tolerance', lactate shuttling, removal, and recycling. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the independent and combined effects of hypoxia (FiO2 = 13.5%) and cold (− 20 °C) on physiological and perceptual responses to endurance exercise. Methods: 14 trained male subjects ( V. O2max: 64 ± 5 mL/kg/min) randomly performed a discontinuous maximal incremental test to exhaustion on a motorized treadmill under four environmental conditions: Normothermic-Normoxia (N), Normothermic-Hypoxia (H), Cold-Normoxia (C) and Cold-Hypoxia (CH). Performance and physiological and perceptual responses throughout exercise were evaluated. Results: Maximal WorkLoad (WL) and WL at lactate threshold (LT) were reduced in C (− 2.3% and − 3.5%) and H (− 18.0% and − 21.7%) compared to N, with no interactive (p = 0.25 and 0.81) but additive effect in CH (− 21.5% and − 24.6%). Similarly, HRmax and Vemax were reduced in C (− 3.2% and − 14.6%) and H (− 5.0% and − 7%), showing additive effects in CH (− 7.7% and − 16.6%). At LT, additive effect of C (− 2.8%) and H (− 3.8%) on HR reduction in CH (− 5.7%) was maintained, whereas an interactive effect (p = 0.007) of the two stressors combined was noted on Ve (C: − 3.1%, H: + 5.5%, CH: − 10.9%). [La] curve shifted on the left in CH, displaying an interaction effect between the 2 stressors on this parameter. Finally, RPE at LT was exclusively reduced by hypoxia (p < 0.001), whereas TSmax is synergistically reduced by cold and hypoxia (interaction p = 0.047). Conclusion: If compared to single stress exposure, exercise performance and physiological and perceptual variables undergo additive or synergistic effects when cold and hypoxia are combined. These results provide new insight into human physiological responses to extreme environments. [ABSTRACT FROM AUTHOR]

This study presents a groundbreaking approach in sports science, introducing a novel graphene oxide (GO) nanosheet-based lactate biosensor designed for the non-invasive, continuous assessment of athlete fitness. Traditional lactate monitoring techniques, typically invasive and offering only intermittent data, are significantly outperformed by this innovative method. Our biosensor uniquely combines lactate oxidase (LOx) with GO nanosheets to measure lactate levels in sweat with unprecedented accuracy and real-time response. Notably, this sensor exhibits exceptional sensitivity and a wide dynamic range, effectively capturing the complete spectrum of physiological lactate variations, from resting states to peak exertion levels. The practical implications of this research are vast, offering a revolutionary tool for enhancing athlete performance monitoring and tailoring training regimens. This biosensor stands as a testament to the potential of nanotechnology in transforming sports science, providing a non-invasive, efficient solution for precise lactate threshold measurement and opening new horizons in personalized athletic training and health monitoring.

Purpose: The purpose of this article was to analyze more than a century of cycling hour records (CHR) to examine the effects of sex, age, and altitude on cycling performance. Our hypotheses were that men's performance (distance) would exceed those of women by more than 10% but would decline at similar rates with aging and that altitude would have a small benefit, which might reach a maximum. Methods: Data were cultivated from the Facebook World Hour Record Discussion Group's crowd-sourced database of more than 600-known-hour records and verified through extensive online research and/or personal communication. Regression and statistical modeling were produced using STATA v15.0. R 2 values were used to ascertain model quality, with four distinct models being produced for comparisons. Alpha was set at 0.05 significance for all tests. Results: R 2 values ranged from 65% to 74.9%. Women's distances were 10.8% shorter (P < 0.001) than those of men, but the difference was narrower than either the historical elite women's difference of 14.2% or the 2022 record difference of 13.3%. Age-related decline modeling indicates performance declines significantly past age 40 yr at a rate of 1.08% per year. Altitude had a significant (P < 0.001) marginal improvement up to 1000 m before declining. The marginal benefits of altitude were small, but this is consistent with the finding benefits reach a maximum at a moderate altitude with "benefits" becoming ambiguous starting at ~1000 m. Technological advancement was estimated to be a small but significant (P < 0.001) improvement of ~0.18% per year. Conclusions: Across decades of CHR data in well-trained endurance cyclists, men are only ~11% faster, and this difference remains stable until at least age 80 yr. CHR attempts greater than 500 m likely offer at best a small advantage. Despite small year-on-year improvements, the CHR has likely improved more than 10 km because of technological advancements. [ABSTRACT FROM AUTHOR]

Acute Ingestion of a Ketone Monoester without Co-ingestion of Carbohydrate Improves Running Economy in Male Endurance Runners. Med. Sci. Sports Exerc., Vol. 56, No. 1, pp. 134-142, 2024. Purpose: Acute ingestion of a ketone monoester, with and without co-ingestion of carbohydrate, was investigated for effects on running economy (RE), time to exhaustion (TTE), and other related indices of endurance running performance. Methods: Using a three condition, placebo-controlled, randomized crossover design, 11 male middle- and long-distance runners ran at five submaximal speeds (10–14 km·h−1 ) on a motorized treadmill for 8 min each, immediately followed by a ramp test to volitional exhaustion. Participants consumed either a 10% carbohydrate solution (CHO), a 10% carbohydrate solution with 750 mg·kg−1 body mass of an (R)-3-hydroxybutyl (R)-3-hydroxybutyrate ketone monoester (CHO + KE), or 750 mg·kg−1 body mass of the ketone monoester in flavored water (KE) before (two-thirds of the dose) and during (one-third of the dose) exercise. Results: β-hydroxybutyrate concentration averaged 1.8 ± 0.3 and 2.1 ± 0.3 mM during exercise in CHO + KE and KE, respectively. RE was lower at each submaximal running speed (effect size = 0.48–0.98) by an average of 4.1% in KE compared with CHO, but not between CHO + KE and CHO. TTE did not differ between CHO (369 ± 116 s), CHO + KE (342 ± 99 s), or KE (333 ± 106 s) (P = 0.093). Conclusions: Acute ingestion of a ketone monoester without carbohydrate, but not when coingested with carbohydrate, improved RE in middle- and long-distance runners at a range of submaximal running speeds and did not alter TTE in a short-duration ramp test to volitional exhaustion. Further investigation is required to examine if these differences translate into positive performance outcomes over longer durations of exercise. [ABSTRACT FROM AUTHOR]

Abstract Background First evidence indicates that the supplementation of specific collagen peptides (SCP) is associated with a significant improvement in running performance in physically active women; however, it is unclear if the same is true in males. The purpose of the present study was to investigate the effects of a concurrent training program including 60 min of continuous moderate intensity running training and 15 min of dynamic resistance training combined with supplementation of SCP on parameters of running performance in moderately trained males. Methods In a double-blind, placebo-controlled, randomized trial, participants performed a 12 weeks concurrent training and ingested 15 g of SCP [treatment group (TG)] or placebo [control group (CG)] daily. Before and after the intervention, running endurance performance was measured by a 1-h time trial on a running track. Velocity at the lactate threshold (V LT) and at the individual anaerobic threshold (V IAT) were assessed on a treadmill ergometer. Body composition was evaluated by bioelectrical impedance analysis. Results Thirty-two men (28.4 ± 5.2 years) completed the study and were included in the analysis. After 12 weeks, TG had a statistically significant (p ≤ 0.05) higher increase in running distance (1727 ± 705 m) compared to the CG (1018 ± 976 m) in the time trial. V LT increased in the TG by 0.680 ± 1.27 km h−1 and slightly decreased by − 0.135 ± 0.978 km h−1 in the CG, resulting in statistically significant group differences (p ≤ 0.05). A significantly higher improvement in V IAT (p ≤ 0.05) was shown in the TG compared with the CG only (1.660 ± 1.022 km h−1 vs 0.606 ± 0.974 km h−1; p ≤ 0.01). Fat mass decreased (TG − 1.7 ± 1.6 kg; CG − 1.2 ± 2.0 kg) and fat free mass increased (TG 0.2 ± 1.2 kg; CG 0.5 ± 1.3 kg) in both groups with no significant group differences. Conclusion In summary, supplementation with 15 g of SCP improved running performance in a 1-h time trial and enhanced indicators of endurance capacity at submaximal exercise intensities such as an increased velocity at the lactate as well as the anaerobic threshold more effectively than CT alone. Trial registration: ETK: 123/17; DRKS-ID: DRKS00015529 (Registered 07 November 2018—Retrospectively registered); https://drks.de/search/de/trial/DRKS00015529

Via the identification of the ramp-specific gas exchange threshold (GET) and respiratory compensation point (RCP), the recently validated step--ramp--step (SRS) protocol enables the prediction of the power outputs at the lactate threshold and maximal metabolic steady state. Purpose: We aimed to test the extended capabilities of the SRS protocol by validating its capacity to predict the power outputs for targeted metabolic rates (VO2) and time-to-task failure (Tlim) within the heavy- and severe-intensity domain, respectively. Methods: Fourteen young individuals completed (i) an SRS protocol from which the power outputs at GET and RCP (RCPCORR), and the work accruable above RCPCORR, defined as WRAMP, were derived; (ii) one heavy-intensity bout at a power output predicted to elicit a targeted VO2 equidistant from GET and RCP; and (iii) four severe-intensity trials at power outputs predicted to elicit targeted Tlim at minutes 2.5, 5, 10, and 13. These severe-intensity trials were also used to compute the constant-load--derived critical power and W´ (WCONSTANT). Results: Targeted (2.41 ± 0.52 L·min-1) and measured (2.43 ± 0.52 L·min-1) VO2 at the identified heavy-intensity power output (162 ± 43 W) were not different (P = 0.71) and substantially concordant (CCC = 0.95). Likewise, targeted and measured Tlim for the four identified severe-intensity power outputs were not different (P > 0.05), and the aggregated coefficient of variation was 10.7% ± 8.9%. The derived power outputs at RCPCORR (192 ± 53W) and critical power (193 ± 53 W) were not different (P = 0.65) and highly concordant (CCC = 0.99). There were also no differences between WRAMP and WCONSTANT (P = 0.51). Conclusions: The SRS protocol can accurately predict power outputs to elicit discrete metabolic rates and exercise durations, thus providing, with time efficiency, a high precision for the control of the metabolic stimulus during exercise. [ABSTRACT FROM AUTHOR]

Objective: The aim of the current study was to evaluate the physiological and metabolic responses to running with whole-body electromyostimulation (wbEMS) compared to running without electromyostimulation (control, CG). Methods: Twenty healthy participants (9 male/11 female, age 42 ±7 years) conducted an incremental step test with respiratory gas analysis until exhaustion. Trials were conducted as wbEMS and CG in a random order. As outcome measures, (A) objective total exhaustion, (B) athletic responses (max. time and velocity) and (C) physiological and metabolic responses (V'O2/kg, V'E, EE, RER, lactate) were compared. (D) The impact on the skeletal muscle was assessed prior, 48 h & 72 h after trial. Results: During both trials, participants (A) ran until total exhaustion. Nonetheless, (B) time and velocity till exhaustion as well as (C) RER prior to the first lactate threshold and V'E were reduced with wbEMS. All other correlates did not differ significantly between wbEMS and CG. Following 48 h and 72 h after the trial with wbEMS, (D) the impact on the skeletal muscle was 7- to 9-fold higher compared to baseline values. Values differed significantly to those after running without wbEMS. Conclusion: With the additional stimulation during voluntary activation, wbEMS induces earlier fatigue and a shift in energy metabolism toward fat utilization. Even during aerobic endurance tasks, a great impact on the skeletal muscle indicated by the rise in CK could be observed which promotes wbEMS as an alternative training stimulus that is easy-to-apply and effective during endurance training. [ABSTRACT FROM AUTHOR]

Background: First evidence indicates that the supplementation of specific collagen peptides (SCP) is associated with a significant improvement in running performance in physically active women; however, it is unclear if the same is true in males. The purpose of the present study was to investigate the effects of a concurrent training program including 60 min of continuous moderate intensity running training and 15 min of dynamic resistance training combined with supplementation of SCP on parameters of running performance in moderately trained males. Methods: In a double-blind, placebo-controlled, randomized trial, participants performed a 12 weeks concurrent training and ingested 15 g of SCP [treatment group (TG)] or placebo [control group (CG)] daily. Before and after the intervention, running endurance performance was measured by a 1-h time trial on a running track. Velocity at the lactate threshold (VLT) and at the individual anaerobic threshold (VIAT) were assessed on a treadmill ergometer. Body composition was evaluated by bioelectrical impedance analysis. Results: Thirty-two men (28.4 ± 5.2 years) completed the study and were included in the analysis. After 12 weeks, TG had a statistically significant (p ≤ 0.05) higher increase in running distance (1727 ± 705 m) compared to the CG (1018 ± 976 m) in the time trial. VLT increased in the TG by 0.680 ± 1.27 km h−1 and slightly decreased by − 0.135 ± 0.978 km h−1 in the CG, resulting in statistically significant group differences (p ≤ 0.05). A significantly higher improvement in VIAT (p ≤ 0.05) was shown in the TG compared with the CG only (1.660 ± 1.022 km h−1 vs 0.606 ± 0.974 km h−1; p ≤ 0.01). Fat mass decreased (TG − 1.7 ± 1.6 kg; CG − 1.2 ± 2.0 kg) and fat free mass increased (TG 0.2 ± 1.2 kg; CG 0.5 ± 1.3 kg) in both groups with no significant group differences. Conclusion: In summary, supplementation with 15 g of SCP improved running performance in a 1-h time trial and enhanced indicators of endurance capacity at submaximal exercise intensities such as an increased velocity at the lactate as well as the anaerobic threshold more effectively than CT alone. Trial registration: ETK: 123/17; DRKS-ID: DRKS00015529 (Registered 07 November 2018—Retrospectively registered); https://drks.de/search/de/trial/DRKS00015529 [ABSTRACT FROM AUTHOR]

Watts, SP, Binnie, MJ, Goods, PSR, Hewlett, J, Fahey-Gilmour, J, and Peeling, P. Demarcation of intensity from 3 to 5 zones aids in understanding physiological performance progression in highly trained under-23 rowing athletes. J Strength Cond Res 37(11): e593-e600, 2023--The purpose of this investigation was to compare 2 training intensity distribution models (3 and 5 zone) in 15 highly trained rowing athletes (n58 male; n57 female; 19.461.1 years) to determine the impact on primary (2,000-m single-scull race) and secondary (2,000-m ergometer time trial, peak oxygen consumption [V̇O2peak], lactate threshold 2 [LT2 power]) performance variables. Performance was assessed before and after 4 months training, which was monitored through a smart watch (Garmin Ltd, Olathe, KS) and chest-strap heart rate (HR) monitor (Wahoo Fitness, Atlanta, GA). Two training intensity distribution models were quantified and compared: a 3-zone model (Z1: between 50% V̇O2peak and lactate threshold 1 (LT1); Z2: between LT1 and 95% LT2; Z3: .95% LT2) and a 5-zone model (T1-T5), where Z1 and Z3 were split into 2 additional zones. There was significant improvement in LT2 power for both male (4.08% 6 1.83, p, 0.01) and female (3.52% 6 3.38, p 5 0.02) athletes, with male athletes also demonstrating significant improvement in 2,000-m ergometer time trial (2.3% 6 1.92, p 5 0.01). Changes in V̇O2peak significantly correlated with high-quality aerobic training (percent time in T2 zone; r5 0.602, p 50.02), whereas changes in LT2 power significantly correlated with "threshold" training (percent time in T4 zone; r50.529, p50.04). These correlations were not evident when examining intensity distribution through the 3-zone model. Accordingly, a 5-zone intensity model may aid in understanding the progression of secondary performance metrics in rowing athletes; however, primary (on-water) performance remains complex to quantify. [ABSTRACT FROM AUTHOR]

Blood markers of muscle microdamage and systemic inflammation do not adequately explain the reduced performance observed over a prolonged recovery after running a mountain ultramarathon. This case study aimed to determine whether the reduced performance after the Everesting mountain ultramarathon can be further assessed by considering cardiorespiratory and metabolic alterations determined via repeated incremental and continuous running tests. A single runner (age: 24 years, BM: 70 kg, BMI: 22, Vo2peak: 74 mL∙min−1∙kg−1) was observed over a preparatory period of two months with a one-month recovery period. The Everesting consisted of nine ascents and descents of 9349 vertical metres completed in 18:22 (h:min). During the first phase of the recovery, enhanced peak creatine kinase (800%) and C-reactive protein (44%) levels explained the decreased performance. In contrast, decreased performance during the second, longer phase was associated with a decreased lactate threshold and Vo2 (21% and 17%, respectively), as well as an increased energetic cost of running (15%) and higher endogenous carbohydrate oxidation rates (87%), lactate concentrations (170%) and respiratory muscle fatigue sensations that remained elevated for up to one month. These alterations may represent characteristics that can explain the second phase of the recovery process after Everesting. [ABSTRACT FROM AUTHOR]

Seventeen young healthy physically active males (age 23 ±3 years; body mass (BM) 72.5 ±7.9 kg; height 178 ±4 cm, (mean ±SD)), not specifically trained in cycling, participated in this study. The subjects performed two cycling incremental tests at the pedalling rate of 60 rev·min-1. The first test, with the power output (PO) increases of 30 W every 3 min, was to determine the maximal oxygen uptake (V'O2max) and the power output (PO) at V'O2max, while the second test (series of 6 minutes bouts of increasing intensity) was to determine energy expenditure (EE (V'O2)), gross efficiency (GE (V'O2/PO)) and delta efficiency (DE(DV'O2/ΔPO)) during sub-lactate threshold (LT) PO. V'O2max was 3.79 ±0.40 L·min-1 and the PO at V'O2max was 288 ±27 W. In order to calculate GE and DE the V'O2 was expressed in W, by standard calculations. GE measured at 30 W, 60 W, 90 W and 120 W was 11.6 ±1.4%, 17.0 ±1.4%, 19.6 ±1.2% and 21.4 ±1.1%, respectively. DE was 29.8 ±1.9%. The subjects' BM (range 59-87 kg) was positively correlated with V'O2 at rest (p<0.01) and with the intercept of the linear V'O2 vs. PO relationship (p<0.01), whereas no correlation was found between BM and the slope of V'O2 vs. PO. No correlation was found between BM and DE, whereas GE was negatively correlated with BM (p<0.01). GE was also negatively correlated with V'O2max and the PO at V'O2max (p<0.01). We conclude that: V'O2 at rest affects GE during moderate-intensity cycling and GE negatively corelates with V'O2max and the PO at V'O2max in young healthy men. [ABSTRACT FROM AUTHOR]

Many endurance athletes perform specific blocks of training in hot environments in "heat stress training camps." It is not known if physiological threshold heart rates measured in temperate conditions are reflective of those under moderate environmental heat stress. A total of 16 endurance-trained cyclists and triathletes performed incremental exercise assessments in 18°C and 35°C (both 60% relative humidity) to determine heart rates at absolute blood lactate and ventilatory thresholds. Heart rate at fixed blood lactate concentrations of 2, 3, and 4 mmol·L−1 and ventilatory thresholds were not significantly different between environments (P >.05), despite significant heat stress-induced reductions in power output of approximately 10% to 17% (P <.05, effect size = 0.65–1.15). The coefficient of variation for heart rate at these blood lactate concentrations (1.4%−2.9%) and ventilatory thresholds (2.3%−2.7%) between conditions was low, with significant strong positive correlations between measurements in the 2 environments (r =.92–.95, P <.05). These data indicate heart rates measured at physiological thresholds in temperate environments are reflective of measurements taken under moderate environmental heat stress. Therefore, endurance athletes embarking on heat stress training camps can use heart rate–based thresholds ascertained in temperate environments to prescribe training under moderate environmental heat stress. [ABSTRACT FROM AUTHOR]

The underwater phase (UP) is highly important for overall swimming performance in most swimming events. However, the metabolic effects of the prolonged UP remain unclear. The purpose of this cross-sectional study was to compare the blood lactate response to submaximal front-crawl swimming with short and extended UP. Twelve (four females) junior competitive swimmers (aged 15.4 (1.4) years) undertook 200 m front-crawl swim trials in a 25 m pool at a pre-determined “anaerobic threshold” velocity on two occasions using short (p < 0.001). All-out 25 m swimming with p > 0.05). In conclusion, extending UP of submaximal front-crawl swimming close to maximally allowed during the races substantially increases blood lactate accumulation, i.e., increases the reliance on anaerobic metabolism. Therefore, extended UP is most likely counterproductive for the performance in long-distance swimming, at least for the athletes with a FINA score of

Purpose: To identify the anaerobic threshold through the lactate threshold determined by Dmax and rating of perceived exertion (RPE) threshold by Dmax and to evaluate the agreement and correlation between lactate threshold determined by Dmax and RPE threshold by Dmax during an incremental test performed on the treadmill in long-distance runners. Methods: A total of 16 long-distance runners volunteered to participate in the study. Participants performed 2 treadmill incremental tests for the collection of blood lactate concentrations and RPE separated by a 48-hour interval. The incremental test started at 8 km·h−1, increasing by 1.2 km·h−1 every third minute until exhaustion. During each stage of the incremental test, there were pauses of 30 seconds for the collection of blood lactate concentration and RPE. Results: No significant difference was found between methods lactate threshold determined by Dmax and RPE threshold by Dmax methods (P =.664). In addition, a strong correlation (r =.91) and agreement through Bland–Altman plot analysis were found. Conclusions: The study demonstrated that it is possible to predict anaerobic threshold from the OMNI-walk/run scale curve through a single incremental test on the treadmill. However, further studies are needed to evaluate the reproducibility and objectivity of the OMNI-walk/run scale for anaerobic threshold determination. [ABSTRACT FROM AUTHOR]

This is a two-part study to determine one or more reliable physiological anchors for perception of effort. The purpose of Study 1 was to compare ratings of perceived exertion (RPE) at the ventilatory threshold (VT) in running, cycling, and upper body exercise with the premise that if RPE at VT did not differ across exercise modes, VT might provide a unique set of physiological inputs for perception of effort. For 27 participants, values for VT and for RPE at VT (Borg 6 to 20 scale) averaged 9.4 km⋅h−1 (SD = 0.7) and 11.9 km⋅h−1 (SD = 1.4) respectively in running, 135 W (SD = 24) and 12.1 W (SD = 1.6) in cycling, and 46 W (SD = 5) and 12.0 W (SD = 1.7) in upper body exercise. RPE did not differ, suggesting that VT may anchor effort perception. In Study 2, 10 participants performed cycle ergometer exercise for 30 minutes at their VT (M = 101 W, SD = 21), at their maximal lactate steady state (M = 143 W, SD = 22), and at their critical power (CP; M = 167 W, SD = 23). Mean end-exercise RPE were 12.1 (SD = 2.1), 15.0 (SD = 1.9), and 19.0 (SD = 0.5), respectively. The very close clustering of RPE during exercise at CP hints that the confluence of physiological responses at CP may (also) serve as a determinant in perception of effort. [ABSTRACT FROM AUTHOR]

This systematic review and meta-analysis aims to provide meta-analytic estimates of the relationships between repeated sprint ability (RSA) outputs (total sprint time [TST] and fatigue scores) and aerobic capacity indicators (VO2max, the covered distance in the endurance shuttle run test [SRTdistance], and the velocity at the anaerobic lactate threshold [ALTvelocity]). To identify potential studies for inclusion, a search strategy was implemented on MEDLINE (through PubMed) and Web of Science. The correlation coefficients between RSA outputs and aerobic capacity indicators were extracted from the individual studies to reveal a pooled correlation. After the identification of studies providing inclusion criteria, 45 studies consisting of 1,488 accumulated participants were included. Meta-analysis showed the positive moderate relationships between TST and VO2max (pooled r = 0.444, p < 0.001), TST and SRTdistance (pooled r = 0.465, p < 0.001), TST and ALTvelocity (pooled r = 0.527, p < 0.001), RSA fatigue score and VO2max (pooled r = 0.449, p < 0.001), and RSA fatigue score and ALTvelocity (pooled r = 0.460, p < 0.001), which showed a low positive relationship between RSA fatigue score and SRTdistance (pooled r = 0.305, p = 0.029). This study showed pooled correlations between RSA outputs and practical aerobic capacity indicators. However, contrary to popular belief that there were stronger relationships, these relationships were low to moderate [ABSTRACT FROM AUTHOR]

How exercise intensity targets, calibrated according to oxygen consumption, relate to vertical impacts during weight-bearing exercise is currently unknown. The authors investigated the relationship between vertical peaks (VPs) and metabolic equivalents (METs) of oxygen consumption in 82 women during walking and running. The magnitude of VPs, measured using a hip-worn triaxial accelerometer, was derived from recommended aerobic exercise intensity targets. VPs were 0.63 ± 0.18g at the lower recommended absolute exercise intensity target (3 METs) but >1.5g at the upper end of moderate-intensity activities (1.90 ± 1.13g at 6 METs). Multilevel linear regression analyses identified speed and type of locomotion as the strongest independent predictors of VPs, explaining 54% and 11% of variance, respectively. The authors conclude that, in contrast to lower intensities, exercising close to or above the 6-MET threshold generates VPs of osteogenic potential, suggesting this could provide simultaneous benefits to decrease all-cause mortality and osteoporosis risk. [ABSTRACT FROM AUTHOR]

Purpose: Long-distance cross-country skiers specialize to compete in races >50 km predominantly using double poling (DP). This emphasizes the need for highly developed upper-body endurance capacities and an efficient DP technique. The aim of this study was to investigate potential effects of specialization by comparing physiological capacities and kinematics in DP between long-distance skiers and skiers competing using both techniques (skating/classic) in several competition formats ("all-round skiers"). Methods: Seven male long-distance (32 [6] y, 183 [6] cm, 76 (5] kg) and 6 all-round (25 [3] y, 181 [5] cm, 75 [6] kg) skiers at high international levels conducted submaximal workloads and an incremental test to exhaustion for determination of peak oxygen uptake (VO2peak) and time to exhaustion (TTE) in DP and running. Results: In DP and running maximal tests, TTE showed no difference between groups. However, long-distance skiers had 5-6% lower VCLpeak in running (81 [5] vs 85 [3] mL·kg-1·min-1; P = .07) and DP (73 [3] vs 78 [3] mL·kg-1·min-1; P < .01) than all-round skiers. In DP, long-distance skiers displayed lower submaximal O2 cost than all-round skiers (3.8±3.6%; P < .05) without any major differences in cycle times or cyclic patterns of joint angles and center of mass. Lactate concentration over a wide range of speeds (45-85% of VO2peak) did not differ between groups, even though each workload corresponded to a slightly higher percentage of VO2peak for long-distance skiers (effect size: 0.30-0.68). Conclusions: The long-distance skiers displayed lower VO2peak but compensated with lower O2 cost to perform equally with the all-round skiers on a short TTE test in DP. Furthermore, similar submaximal lactate concentration and reduced 0 2 cost could be beneficial in sustaining high skiing speeds in long-duration competitions. [ABSTRACT FROM AUTHOR]

The relationship between the onset of sweating (OS) and sweat lactate threshold (sLT) assessed using a novel sweat lactate sensor remains unclear. We aimed to investigate the implications of the OS on the sLT. Forty healthy men performed an incremental cycling test. We monitored the sweat lactate, blood lactate, and local sweating rates to determine the sLT, blood LT (bLT), and OS. We defined participants with the OS during the warm-up just before the incremental test as the early perspiration (EP) group and the others as the regular perspiration (RP) group. Pearson's correlation coefficient analysis revealed that the OS was poorly correlated with the sLT, particularly in the EP group (EP group, r = 0.12; RP group, r = 0.56). Conversely, even in the EP group, the sLT was strongly correlated with the bLT (r = 0.74); this was also the case in the RP group (r = 0.61). Bland-Altman plots showed no bias between the mean sLT and bLT (mean difference: 19.3 s). Finally, in five cases with a later OS than bLT, the sLT tended to deviate from the bLT (mean difference, 106.8 s). The sLT is a noninvasive and continuous alternative to the bLT, independent of an early OS, although a late OS may negatively affect the sLT. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to examine how respiratory (RT) and lactate thresholds (LT) are affected by acute heat exposure in the two most commonly used incremental exercise test protocols (RAMP and STEP) for functional evaluation of aerobic fitness, exercise prescription and monitoring training intensities. Methods: Eleven physically active male participants performed four incremental exercise tests, two RAMP (30 W·min−1) and two STEP (40 W·3 min−1), both in 18 °C (TEMP) and 36 °C (HOT) with 40% relative humidity to determine 2 RT and 16 LT, respectively. Distinction was made within LT, taking into account the individual lactate kinetics (LTIND) and fixed value lactate concentrations (LTFIX). Results: A decrease in mean power output (PO) was observed in HOT at LT (−6.2 ± 1.9%), more specific LTIND (−5.4 ± 1.4%) and LTFIX (−7.5 ± 2.4%), compared to TEMP, however not at RT (−1.0 ± 2.7%). The individual PO difference in HOT compared to TEMP over all threshold methods ranged from −53 W to +26 W. Mean heart rate (HR) did not differ in LT, while it was increased at RT in HOT (+10 ± 8 bpm). Conclusion: This study showed that exercise thresholds were affected when ambient air temperature was increased. However, a considerable degree of variability in the sensitivity of the different threshold concepts to acute heat exposure was found and a large individual variation was noticed. Test design and procedures should be taken into account when interpreting exercise test outcomes. [ABSTRACT FROM AUTHOR]

Endurance running performance can be predicted by maximal oxygen uptake (V̇O2 max), the fractional utilisation of oxygen uptake (%V̇O2 max) and running economy at lactate threshold (REOBLA). This study aims to assess maximal lactate accumulation rate (ċLamax) in terms of improving running performance prediction in trained athletes. Forty-four competitive female and male runners/triathletes performed an incremental step test, a 100-m sprint test and a ramp test to determine their metabolic profile. Stepwise linear regression was used to predict 5000-m time trial performance. Split times were recorded every 200-m to examine the 'finishing kick'. Females had a slower t5k and a lower V̇O2 max, ċLamax , 'finishing kick' and REOBLA. Augmenting Joyner's model by means of ċLamax explained an additional 4.4% of variance in performance. When performing the same analysis exclusively for males, ċLamax was not included. ċLamax significantly correlated with %V̇O2 max (r=-0.439, p=0.003) and the 'finishing kick' (r=0.389, p=0.010). ċLamax allows for significant (yet minor) improvements in 5000-m performance prediction in a mixed-sex group. This margin of improvement might differ in middle-distance events. Due to the relationship to the 'finishing kick', ċLamax might be related to individual pacing strategies, which should be assessed in future research. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determining the range of aerobic exercise on a treadmill for male Wistar rats at different ages. Twelve male Wistar rats were divide in three groups of immature, adults, and old (n= 4 in each). At first session, the rats began to run at a rate of 2 m/min to perform the fatigue test, and the treadmill speed was increased by 2 m/min every 2 minutes. This process of acceleration continued until the rats were no longer able to continue moving on the treadmill and became exhausted. Then, blood lactate of each subject measured immediately and their maximum speed was recorded. After 48 hours of recovery, animal performed maximum recorded speed on a treadmill in three 10-minute steps of 25%, 50% and 75%, respectively. Immediately after each percent blood lactate were measured and recorded. Immature rats at an average speed of 18 m/min were reached to their maximum speed with an average lactate concentration of 8±1.8 mmol/l. Adults rats at an average speed of 36 m/min were reached to their maximum speed with an average lactate concentration of 6.8±0.4 mmol/l. The old rats reached their maximum velocity with an average of 30 m/min with an average lactate concentration of 6.95±0.9 mmol/l. Therefore, it recommended that aerobic exercise in untrained rats start at a light speed, i.e. 25% of their maximum speed, which is lower than the lactate threshold, and gradually continue up to 50% of their maximum speed.

PURPOSE To investigate the effect of a 4-week training using a laboratory index on the competition record of elite female middle-distance runners. METHODS A female, middle-distance, trained runner with the following characteristics: age, 20 years; height, 168.7 cm; weight, 64.3 kg; 27.2% fat; and VO2max, 56.4 VO2 mL/kg/min; volunteered to participate in this study. Before the training program, the participant took part in a 1,500-m track and field national event in April and the onset of blood lactate threshold was analyzed using (OBVA/ vOBLA), VO2max/vVO2max, and tVO2max tests. After completing the 4-week training program, the participant again took part in the 1,500-m track and field national event in May and her parameters were reassessed using the OBVA/vOBLA, VO2max/vVO2max, and tVO2max tests. RESULTS Pre- and post-training indicate that vVO2max did not improve; however, tVO2max (206 seconds pre-training vs. 251.51 seconds post-training) and VO2max (56.4 vs. 59.3 VO2 mL/kg/min)significantly. However, this improvement in relative VO2 was due to weight loss, and the absolute value of VO2 (3.63 vs. 3.62 L/min) did not change. The 1,500-m race record in track and field events decreased significantly from a pre-training value of 5 minutes 03 seconds to a post-training value of 4 minutes 52 seconds. CONCLUSIONS The results of this study indicate that utilizing laboratory indicators including vOBLA, vVO2max, and tVO2max may be extremely valuable when prescribing training programs for middle-distance runners.

For the past 200 years, lactate has been regarded as a metabolic waste end product that causes fatigue during exercise. However, lactate production is closely correlated with energy metabolism. The lactate dehydrogenase-catalyzed reaction uses protons to produce lactate, which delays ongoing metabolic acidosis. Of note, lactate production differs depending on exercise intensity and is not limited to muscles. Importantly, controlling physiological effect of lactate may be a solution to alleviating some chronic diseases. Released through exercise, lactate is an important biomarker for fat oxidation in skeletal muscles. During recovery after sustained strenuous exercise, most of the lactate accumulated during exercise is removed by direct oxidation. However, as the muscle respiration rate decreases, lactate becomes a desirable substrate for hepatic glucose synthesis. Furthermore, improvement in brain function by lactate, particularly, through the expression of vascular endothelial growth factor and brain-derived neurotrophic factor, is being increasingly studied. In addition, it is possible to improve stress-related symptoms, such as depression, by regulating the function of hippocampal mitochondria, and with an increasingly aging society, lactate is being investigated as a preventive agent for brain diseases such as Alzheimer's disease. Therefore, the perception that lactate is equivalent to fatigue should no longer exist. This review focuses on the new perception of lactate and how lactate acts extensively in the skeletal muscles, heart, brain, kidney, and liver. Additionally, lactate is now used to confirm exercise performance and should be further studied to assess its impact on exercise training. [ABSTRACT FROM AUTHOR]

There is current scientific interest in naturally sourced phenolic compounds and their potential benefits to health, as well as the effective role polyphenols may provide in an exercise setting. This study investigated the chronic effects of supplementation with a biodynamic and organic olive fruit water phytocomplex (OliPhenolia® [OliP]), rich in hydroxytyrosol (HT), on submaximal and exhaustive exercise performance and respiratory markers of recovery. Twenty-nine recreationally active participants (42 ± 2 yrs; 71.1 ± 2.1 kg; 1.76 ± 0.02 m) consumed 2 × 28 mL∙d−1 of OliP or a taste- and appearance-matched placebo (PL) over 16 consecutive days. Participants completed a demanding, aerobic exercise protocol at ~75% maximal oxygen uptake ( V ˙ O2max) for 65 min 24 h before sub- and maximal performance exercise tests prior to and following the 16-day consumption period. OliP reduced the time constant (τ) (p = 0.005) at the onset of exercise, running economy (p = 0.015) at lactate threshold 1 (LT1), as well as the rating of perceived exertion (p = 0.003) at lactate turnpoint (LT2). Additionally, OliP led to modest improvements in acute recovery based upon a shorter time to achieve 50% of the end of exercise V ˙ O2 value (p = 0.02). Whilst OliP increased time to exhaustion (+4.1 ± 1.8%), this was not significantly different to PL (p > 0.05). Phenolic compounds present in OliP, including HT and related metabolites, may provide benefits for aerobic exercise and acute recovery in recreationally active individuals. Further research is needed to determine whether dose-response or adjunct use of OliP alongside longer-term training programs can further modulate exercise-associated adaptations in recreationally active individuals, or indeed support athletic performance. [ABSTRACT FROM AUTHOR]

Background and Purpose: Aerobic fitness is one of the factors influencing the success of rowers in rowing, which requires the use of efficient training methods. Polarized training model based on the intensity distribution of the training would be a suitable strategy in this field. Therefore, the aim of this study was to investigate the effect of four weeks of polarized training on aerobic fitness and performance of professional rowers. Materials and Methods: 20 athletes (10 females and 10 males) who had more than two years of professional rowing experience were divided into two groups of polarized training intensity distribution (75-80% of training volume equivalent to 18 training sessions in zone one with 55-75% of maximum heart rate, 5-10% of the training volume is equivalent to eight training sessions in zone two with 81-87% maximum heart rate and 15-20% of the training volume is equivalent to four training sessions with 88-100% maximum heart rate) and traditional training intensity distribution (20% of training volume in zone one, equivalent to seven sessions per month, 50% in zone two, including 12 sessions per month, and 30% in zone three, including five sessions) were divided and their exercises were performed over four weeks, with six sessions per week (three sessions of rowing + One session of ergometer + two sessions of running) was followed. Before and after the training period, maximal oxygen consumption, respiratory exchange ratio, blood lactate, time of 2000 and 1000 meters were evaluated. Repeated analysis of variance with intergroup factor was used to examine the research data (P ≤ 0.05). Results: According to the results of the present study, the performance of 2000 meters in both groups improved significantly (P < 0.0001). This improvement was 5.56% more reduction in 2000 meters' record, which shows the greater effectiveness of this training method. However, the performance of 1000 m after four weeks of polarized and traditional training was similar (P = 0.37). There was no significant difference between the two groups for Maximum oxygen consumption (P = 0.14) and respiratory exchange ratio (P = 0.21). Fat percentage in both groups decreased significantly (P = 0.001). Conclusion: Despite the lack of differences in some physiological parameters, four weeks of traditional and polarized training are associated with improved performance and physiological parameters of rowers, which is greater in the performance of 2000 meters that is the main competition of these athletes with polarized training (about 6%). It seems that the polarization intensity distribution pattern can be a more effective method than traditional exercises in developing the aerobic performance characteristics of rowing athletes. [ABSTRACT FROM AUTHOR]

Stride-to-stride variability and fluctuations in running have been widely investigated in relation to fatigue, injury, and other factors. However, no studies have examined the relationship of stride-to-stride variability and fluctuations with lactate threshold (LT), a well-known performance indicator for distance runners that represents the threshold at which fast-twitch muscle fibers are activated and the glycolytic system is hyperactivated. In this study, we examined a relationship between LT and stride-to-stride variability and fluctuations in trained middle- and long-distance runners (n = 33). All runners were asked to perform multistage graded exercise tests while wearing accelerometers on the upper surface of their shoes. The LT was determined by measuring blood lactate concentrations after each stage. Three gait parameters for each step were calculated based on the acceleration data: stride time (ST), ground contact time (CT), and peak acceleration (PA). The coefficient of variation (CV) and the long-range correlations (α) for each parameter were also calculated. The effects of the runner's group and the relative intensity for CV and α on gait parameters were evaluated using a two-way repeated measures analysis of variance. Although no significant effect was observed in the CV and α of ST, significant intensity main effects were observed for the CV and α of CT and PA. The lack of significant changes in ST might be the result of runners' adequate control of ST to minimize energy cost. All the parameters showing significant changes with increasing intensity decreased dramatically when they were close to LT. This might have been caused by an increase in physiological load near LT and be interpreted as a variation in motor control because of alternations in the mobilized muscle fibers and physiological changes around the LT. The α should be useful for non-invasive LT detection.

Purpose: Trail running is a complex sport, and performance prediction is challenging. The aim was to evaluate 3 standard laboratory exercise tests in trail runners and correlate measurements to the race time of a trail competition evaluating its predictive power. Methods: Nine competitive male trail runners (mean age: 31 [5.8] y) completed 3 different laboratory exercise tests (step, ramp, and trail tests) for determination of maximal oxygen uptake (VO2max), vVO2max, ventilatory (VT) and lactate thresholds (LT), mechanical power output, and running economy (RE), followed by a 31-km trail race. Runners had previously participated in the same race (previous year) and finished in the top 2%. Finishing times (dependent value) were tested in multiple-regression analysis with different independent value combinations. Results: Linear-regression analysis revealed that variables measured during step and ramp tests significantly predicted performance. Step-test variables (speed at individual anaerobic threshold 16.4 [1.7] km/h and RE 12 km/h in %VO2max 65.6% [5.4%]) showed the highest performance prediction (R2 =.651, F2,6 = 5.60, P =.043), followed by the ramp test (vVO2max 20.3 [1.3] km/h; R2 =.477, F1,7 = 6.39, P =.04) and trail test (maximal power 3.9 [0.5] W/kg, VO2max 63.0 [4.8] mL O2·kg−1·min−1, vVT1 11.9 [0.7] km/h; R2 =.68, F3,5 = 3.52, P =.11). Adding race time from the preceding year to the step test improved the predictive power of the model (R2 =.988, F3,5 = 66.51, P <.001). Conclusions: The graded exercise test (VO2max, individual anaerobic threshold, and RE) most accurately predicted a 31.1-km trail-running performance. Combining submaximal intensities (individual anaerobic threshold and RE) with the previous year's race time of that specific event increased the predictive power of the model to 99%. [ABSTRACT FROM AUTHOR]

IntroductionCycling is a time-consuming sport. Cyclists, as many other athletes, therefore, focus on training effectively. The hypothesis was tested that twelve weeks of supplementary maximal acceleration training caused more favourable changes in cycling performance indicators as compared to changes measured in comparable control cyclists.MethodsTrained cyclists (n = 24) participated. A control group and a group performing maximal acceleration training, as a supplement to their usual training, were formed. The maximal acceleration training consisted of series of ten repetitions of outdoor brief maximal accelerations, which were initiated from low speed and performed in a large gear ratio. The cyclists in the control group performed their usual training. Performance indicators, in form of peak power output in a 7-s maximal isokinetic sprint test, maximal aerobic power output in a graded test, and submaximal power output at a predetermined blood lactate concentration of 2.5 mmol L−1 in a graded test were measured before and after the intervention.ResultsPeak power output in the sprint test was increased (4.1% from before to after the intervention) to a larger extent (p = 0.045) in the cyclists who had performed the maximal acceleration training than in the control cyclists (−2.8%). Changes in maximal aerobic power output and in submaximal power output at a blood lactate concentration of 2.5 mmol L−1 were not significantly different between the groups (p > 0.351).DiscussionThe results indicated that the applied supplementary maximal acceleration training caused modest favourable changes of performance indicators, as compared to the changes measured in a group of comparable control cyclists.

Background: Modern pentathlon includes horse riding, fencing, swimming, shooting and cross-country running. Events can last many hours during which the athletes face almost maximal energy and physiological demands, and fatigue. Early recognition and prevention of injuries and overuse syndromes can be achieved by refining the individual training loads. The purpose of the study was to determine which parameter could be the most accurate predictor of swimming working capacity determinants in pentathletes. Methods: Fourteen male pentathletes performed a continuous maximal incremental test in the swimming flume ergometer to measure peak oxygen uptake (VO2peak), and five swimming tests in a 50 m swimming pool to detect critical velocity (CV); velocity at 2 and 4 mM·L−1 of blood lactate (v2, v4) and energy cost (EC). Results: The 200 m swimming time was 2:18–2:32 m:s (340 FINA points). CV was 1.21 ± 0.04 m·s−1, v2 was 1.14 ± 0.09 and v4 1.23 ± 0.08 m·s−1. VO2peak was 3540.1 ± 306.2 mL·min−1 or 48.8 ± 4.6 mL·kg−1·min−1. EC at 1.24 m·s−1 was 45.7 ± 2.4 mL·kg−1·min−1. Our main finding was the large correlation of CV with 200 m swimming performance; Conclusions: Among all the protocols analysed, CV is the most predictive and discriminative of individual swimming performance in this group of pentathletes. It appears as the most suitable test to constantly refine their swimming training loads for both performance enhancement and health promotion. [ABSTRACT FROM AUTHOR]

The prediction of running performance at different competitive distances is a challenge, since it can be influenced by several physiological, morphological and biomechanical factors. In experienced male runners heterogeneous for maximal oxygen uptake (VO2max), endurance running performance can be well predicted by several key parameters of aerobic fitness such as VO2max and its respective velocity (vVO2max), running economy, blood lactate response to exercise, oxygen uptake kinetics and critical velocity. However, for a homogeneous group of well-trained endurance runners, the relationship between aerobic fitness parameters and endurance running performance seems to be influenced by the duration of the race (i.e., middle vs. long). Although middle-distance and ultramarathon runners present high aerobic fitness levels, there is no accumulating evidence showing that the aerobic key parameters influence both 800-m and ultramarathon performance in homogeneous group of well-trained runners. The vVO2max seems to be the best predictor of performance for 1500 m. For 3000 m, both vVO2max and blood lactate response to exercise are the main predictors of performance. Finally, for long distance events (5000 m, 10,000 m, marathon and ultramarathon), blood lactate response seems to be main predictor of performance. The different limiting/determinants factors and/or training-induced changes in aerobic parameters can help to explain this time- or distance-dependent pattern.

Background/Objectives: The aim of this study was to compare high-intensity interval exercise (HIIE) sessions prescribed on the basis of a maximal value (peak power output, PPO) and a submaximal value (lactate threshold, LT) derived from graded exercise tests (GXTs) in normoxia and hypoxia. Methods: A total of ten males (aged 18–37) volunteered to participate in this study. The experimental protocol consisted of a familiarization procedure, two GXTs under normoxia (FiO2 = 0.209) and two GXTs under normobaric hypoxia (FiO2 = 0.140), and three HIIE sessions performed in a random order. The HIIE sessions included one at hypoxia (HY) and two at normoxia (one matched for the absolute intensity in hypoxia, designated as NA, and one matched for the relative intensity in hypoxia, designated as NR). Results: The data demonstrated that there was significant lower peak oxygen uptake (V̇O2peak), peak heart rate (HRpeak), PPO, and LT derived from GXTs in hypoxia, with higher respiratory exchange ratio (RER), when compared to those from GXTs performed in normoxia (p

Blood markers of muscle microdamage and systemic inflammation do not adequately explain the reduced performance observed over a prolonged recovery after running a mountain ultramarathon. This case study aimed to determine whether the reduced performance after the Everesting mountain ultramarathon can be further assessed by considering cardiorespiratory and metabolic alterations determined via repeated incremental and continuous running tests. A single runner (age: 24 years, BM: 70 kg, BMI: 22, Vo2peak: 74 mL∙min−1∙kg−1) was observed over a preparatory period of two months with a one-month recovery period. The Everesting consisted of nine ascents and descents of 9349 vertical metres completed in 18:22 (h:min). During the first phase of the recovery, enhanced peak creatine kinase (800%) and C-reactive protein (44%) levels explained the decreased performance. In contrast, decreased performance during the second, longer phase was associated with a decreased lactate threshold and Vo2 (21% and 17%, respectively), as well as an increased energetic cost of running (15%) and higher endogenous carbohydrate oxidation rates (87%), lactate concentrations (170%) and respiratory muscle fatigue sensations that remained elevated for up to one month. These alterations may represent characteristics that can explain the second phase of the recovery process after Everesting.

Peak ratios of pulmonary gas-exchange to ventilation during exercise (V˙O2/V˙E and V˙CO2/V˙E, termed "circulatory equivalents") are sensitive to heart failure (HF) severity, likely reflecting low and/or poorly distributed pulmonary perfusion. We tested whether peak V˙O2/V˙E and V˙CO2/V˙E would: (1) distinguish HF patients from controls; (2) be independent of incremental exercise protocol; and (3) correlate with lactate threshold (LT) and ventilatory compensation point (VCP), respectively. Twenty-four HF patients (61±11 years) with reduced ejection fraction (31±8%) and 11 controls (63±7 years) performed ramp-incremental cycle ergometry. Eighteen HF patients also performed slow (5±1 W/min), medium (9±4 W/min), and fast (19±6 W/min) ramps. Peak V˙O2/V˙E and V˙CO2/V˙E from X-Y plot, and LT and VCP from 9-panel plot, were determined by 2 independent, blinded, assessors. Peak V˙O2/V˙E (31.2±4.4 versus 41.8±4.8 mL/L; P

Pulmonary gas exchange analysis was compared to changes in muscle oxygen saturation as measured by near-infrared spectroscopy. First, ventilatory thresholds determined by common gas exchange analysis and breakpoints in muscle oxygen saturation were assessed for agreement during exercise with increasing intensity. Secondly, the relationship between muscle oxygen saturation as a surrogate for local oxygen extraction and peak oxygen uptake was assessed. In order to lend robustness to future NIRS testing on a broader scale, considering its potential for simple and cost-effective application, the question of a running versus a cycling modality was integrated into the design. Ten participants, of whom five were recreationally trained cyclists and five recreationally trained runners, were tested; each during a cycling test and a running test with increasing intensity to voluntary exhaustion. Muscle oxygen saturation and pulmonary gas exchange measurements were conducted. Bland-Altman analysis showed a moderate degree of agreement between both muscle oxygen saturation breakpoint 1 and muscle oxygen saturation breakpoint 2 and corresponding ventilatory threshold 1 and ventilatory threshold 2, for both cycling and running disciplines; generally speaking, muscle oxygen saturation breakpoints underestimated ventilatory thresholds. Additionally, a strong relationship could be seen between peak oxygen uptake and the minimally attained muscle oxygen saturation during cycling exercise. Muscle oxygen saturation measured using NIRS was determined to be a suitable method to assess ventilatory thresholds by finding breakpoints in muscle oxygen saturation, and muscle oxygen saturation minimum was linked to peak oxygen uptake. [ABSTRACT FROM AUTHOR]

Breath analysis was coupled with ergo-spirometry for non-invasive profiling of physio-metabolic status under exhaustive exercise. Real-time massspectrometry based continuous analysis of exhaled metabolites along with breath-resolved spirometry and heart rate monitoring were executed while 14 healthy adults performed ergometric ramp exercise protocol until exhaustion. Arterial blood lactate level was analyzed at defined time points. Respiratory-cardiac parameters and exhalation of several blood-borne volatiles changed continuously with the course of exercise and increasing workloads. Exhaled volatiles mirrored ventilatory and/or hemodynamic effects and depended on the origin and/or physicochemical properties of the substances. At the maximum workload, endogenous isoprene, methanethiol, dimethylsulfide, acetaldehyde, butanal, butyric acid and acetone concentrations decreased significantly by 74, 25, 35, 46, 21, 2 and 2%, respectively. Observed trends in exogenous cyclohexadiene and acetonitrile mimicked isoprene profile due to their similar solubility and volatility. Assignment of anaerobic threshold was possible via breath acetone. Breathomics enabled instant profiling of physio-metabolic effects and anaerobic thresholds during exercise. Profiles of exhaled volatiles indicated effects from muscular vasoconstriction, compartmental distribution of perfusion, extra-alveolar gas-exchange and energy homeostasis. Sulfur containing compounds and butyric acid turned out to be interesting for investigations of combined diet and exercise programs. Reproducible metabolic breath patterns have enhanced scopes of breathomics in sports science/medicine. [ABSTRACT FROM AUTHOR]

The heart rate variability threshold (HRVT) is a useful and inexpensive alternative to estimate the ventilatory threshold (VT). However, its validity in women remains underexplored. We investigated the agreement between HRVT and VT in young women and the influence of cardiac parasympathetic status and cardiorespiratory fitness (CRF). Sixty-one women [Age: 24.5 ± 4.6 years, BMI: 23.4 ± 2.6 kg/m2, V ˙ O2max: 36.6 ± 6.1 (mL (kg.min)−1)] underwent a maximal exercise test on a treadmill. We assessed HRVT using four methods: HRVTvisual, HRVTDmax, HRVT3ms, HRVT1ms. Low bias and limits of agreement were observed between VT and HRVTvisual [−.1 (−1.5. 1.3) km/h] and HRVTDmax [−.1 (−1.6, 1.4) km/h] methods. Higher limits of agreement were observed for HRVT3ms [.1 (−2.1, 2.1) km/h] and HRVT1ms [.4 (−1.8, 2.7) km/h]. In conclusion, acceptable agreement was observed between VT and HRVT in women, mainly when visual and Dmax methods were used for HRVT assessment. [ABSTRACT FROM AUTHOR]

Breath analysis was coupled with ergo-spirometry for non-invasive profiling of physio-metabolic status under exhaustive exercise. Real-time mass-spectrometry based continuous analysis of exhaled metabolites along with breath-resolved spirometry and heart rate monitoring were executed while 14 healthy adults performed ergometric ramp exercise protocol until exhaustion. Arterial blood lactate level was analyzed at defined time points. Respiratory-cardiac parameters and exhalation of several blood-borne volatiles changed continuously with the course of exercise and increasing workloads. Exhaled volatiles mirrored ventilatory and/or hemodynamic effects and depended on the origin and/or physicochemical properties of the substances. At the maximum workload, endogenous isoprene, methanethiol, dimethylsulfide, acetaldehyde, butanal, butyric acid and acetone concentrations decreased significantly by 74, 25, 35, 46, 21, 2 and 2%, respectively. Observed trends in exogenous cyclohexadiene and acetonitrile mimicked isoprene profile due to their similar solubility and volatility. Assignment of anaerobic threshold was possible via breath acetone. Breathomics enabled instant profiling of physio-metabolic effects and anaerobic thresholds during exercise. Profiles of exhaled volatiles indicated effects from muscular vasoconstriction, compartmental distribution of perfusion, extra-alveolar gas-exchange and energy homeostasis. Sulfur containing compounds and butyric acid turned out to be interesting for investigations of combined diet and exercise programs. Reproducible metabolic breath patterns have enhanced scopes of breathomics in sports science/medicine.

Aim. To assess the change in ergoreflex activity in heart failure patients with reduced left ventricular systolic function in the study of the effectiveness of physical training (PT) with original regimen, compared with PT with conventionally estimated regimen.Material and methods. Single-center open-label study of 297 patients with class III HF. The patients were divided into two groups: main group (MG) — patients, in whom the PT intensity was estimated based on lactate threshold (LT); comparison group (CG), in whom the PT intensity was estimated based on 60% VO2peak. We analyzed ergoreflex activity, the relationship of ergoreflex with exercise tolerance (ET), routine systemic inflammation markers, clinical manifestations of HF, and ET based on VO2peak.Results. An increase in gait velocity at the LT level after 3 months of PT was registered in 94% (n=210) of the MG patients. After 3 months, the PT regimen was recalculated according to 60% VO2реак; an increase in gait velocity at this level after 3 months of PT was registered in 70% of CG patients (n=35). The severity of HF decreased in both groups, but the dynamics was more pronounced in the MG, where class II was achieved by 75% of patients (in CG — 44%, p=0,003). In the MG, to a greater extent than in the CG, the ET increased. Ergoreflex activity (according to ΔVE) decreased by ≥15% in 230 (97%) MG patients and in 31 (63%) patients with CG. After the completion of the PT period, when in some patients the HF severity decreased to class II, we revealed a direct association of the ergoreflex value (according to ΔVE) with a greater severity of HF (r=-0,57, p=0,01) and the relationship between the decrease in ergoreflex activity (according to ΔVE), an increase in VO2LT (r=-0,55, p=0,001), VO2peak (r=0,49, p=0,001), a decrease in monocyte count (r=0,63, p=0,01).Conclusion. In stable patients with class III HF receiving the proper disease-modifying therapy, ergoreflex activity is increased and is associated with functional class, ET, and systemic inflammation activity. In the course of physical rehabilitation, a decrease in ergoreflex activity is accompanied by a decrease in functional class, an increase in EF, which is more pronounced with personalized aerobic exercise using LT regimen assessment.