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Objective Many prognostic factors of grade-3 primary graft dysfunction at post-operative day 3 (PGD3-T72) have been reported but intraoperative blood lactate level has not been studied. The present retrospective study was done to test the hypothesis that intraoperative blood lactate level (BLL) could be a predictor of PGD3-T72 after double-lung transplantation. Design Retrospective monocentric cohort study. Setting Foch University Hospital, Suresnes, France. Participants Patients having received a double-lung transplantation between 2012 and 2019. Patients transplanted twice during the study period, having undergone a multi-organ transplantation, or cardiopulmonary bypass, and those under preoperative extracorporeal membrane oxygenation were excluded. Interventions None. Measurements and Main Results Analysis was performed on a cohort of 449 patients. Seventy-two (16%) patients had a PGD3-T72. BLL increased throughout surgery to reach a median value of 2.2 [1.6-3.2] mmol/L in the No-PGD3-T72 group and 3.4 [2.3-5.0] mmol/L in the PGD3-T72 group after second lung implantation. The best predictive model for PGD3-T72 was obtained adding a lactate threshold of 2.6 mmol/L at the end of surgery to the clinical model, the AUC was 0.867 with a sensitivity =76.9%, specificity = 85.4%. Repeated-measures mixed-model of BLL during surgery remained significant after adjustment for covariates (F ratio= 4.22, p Conclusions Blood lactate level increases during surgery and reaches a maximum after the second lung implantation. A value below the threshold of 2.6 mmol/L at the end of surgery has a high negative predictive value for the occurrence of a grade-3 primary graft dysfunction at post-operative day 3.

The effects of a 6-week cycling high-intensity interval training (HIIT) concurrently with protein supplementation on aerobic and anaerobic fitness and body composition in collegiate dancers was investigated. Eighteen participants enrolled in a collegiate dance program were matched into three groups: high-protein (HP; 90 g˙d−1), moderate-protein (MP; 40 g˙d−1), and control (C; 0 g˙d−1). All participants performed a 6-week HIIT intervention. Participants completed a graded exercise test, Wingate anaerobic test (Wingate), and dual energy x-ray absorptiometry scan before and after the intervention. Peak heart rate (HRpeak), peak oxygen uptake (VOpeak), peak power output (PPO), lactate threshold (LT), and ventilatory thresholds 1 (VT1 ) and 2 (VT2) were assessed during the graded exercise test. Peak power output, mean power output (MPO), and fatigue index (FI) were assessed during the Wingate. Lean mass (LM), fat mass (FM), visceral adipose tissue, appendicular skeletal muscle mass, and appendicular skeletal muscle mass index were assessed during dual energy x-ray absorptiometry. Body composition index (BCI) was calculated from pre and post LM and FM. Habitual diet was recorded weekly. Significance was set at p ≤ 0.05. No significant differences in VO2peak and percent fat mass (%FM) were observed between groups prior to the intervention. Significant main effects for time were observed for HRpeak (p = 0.02), VO2peak (p < 0.001), PPO (p < 0.01), LT (p < 0.001), VT1 (p < 0.001), and VT2 (p < 0.001) during the graded exercise test, and PPO (p < 0.01) and FI (p < 0.01) during the Wingate. Significant main effects for time were observed for LM (kg; p = 0.01) and FM (kg; p < 0.01). Body composition index was improved for all groups, however, no significant differences by group were observed. No significant differences were observed between groups for the measured outcomes (p > 0.05). Therefore, there was no effect of protein supplementation in the short 6-week intervention. This cycling based HIIT routine increased physical fitness, optimized aesthetics, and was a simple addition to an existing collegiate dance curriculum.

Purpose: Exertional-heat stress adversely distrupts (GI) barrier integrity and, through subsequent microbial translocation (MT), can result in potentially fatal exertional-heat stroke. Acute glutamine (GLN) supplementation is a potential nutritional countermeasure, although the practical value of current supplementation regimens is questionable.Method: Ten males completed two high-intensity exertional-heat stress tests (EHST) involving running in the heat (40°C and 40% relative humidity) at lactate threshold to volitional exhaustion. Participants ingested GLN (0.3 g kg FFM-1) or a non-calorific placebo (PLA) one hour prior to the EHST. Venous blood was drawn pre-, post- and one-hour post-EHST. GI permeability was assessed using a serum dual-sugar absorption test (DSAT) and small intestinal epithelial injury using plasma Intestinal Fatty-Acid Binding Protein (I-FABP). MT was assessed using the Bacteroides/total 16S DNA ratio.Results: Volitional exhaustion occurred after 22:19 ± 2:22 (minutes: seconds) in both conditions, during which whole-body physiological responses and GI symptoms were not different (p > 0.05). GI permeability (serum DSAT) was greater following GLN (0.043 ± 0.020) than PLA (0.034 ± 0.019) (p = 0.02; d = 0.47), but small intestine epithelial injury (I-FABP) increased comparably (p = 0.22; ηp2 = 0.16) following the EHST in both trials (GLN Δ = 1.25 ± 0.63 ng ml-1; PLA Δ = 0.92 ± 0.44 ng ml-1). GI MT (Bacteroides/total 16S DNA ratio) was unchanged in either condition following the EHST (p = 0.43).Conclusion: Acute low-dose (0.3 g kg-1 fat free mass) GLN supplementation ingested one hour before high-intesity exertional-heat stress worsened GI permeability, but did not influence either small intestinal epithilial injury or microbial translocation.Abbreviations: ANOVA: Analysis of variance; CV: Coefficient of Variation; DSAT: Dual Sugar Absorption Test; EDTA: Ethylenediaminetetraacetic acid; EHST: Exertional Heat Stress Test; ELISA: Enzyme Linked Immunosorbent Assay; FFM: Fat Free Mass; GI: Gastrointestinal; GFR: Glomerular Filtration Rate; GLN: Glutamine; HPLC: High Performance Liquid Chromatography; HR: Heart Rate; I-FABP: Intestinal Fatty-Acid Binding Protein; ISAK: International Society for the Advancement of Anthropometric Kinanthropometry; L/R: Lactulose-to-Rhamnose; LT: Lactate Threshold; MT: Microbial Translocation; mVAS: Modified Visual Analogue Scale; PBS: Phosphate-Buffered Saline; PLA: Placebo; qPCR: Quantitative Polymerase Chain Reaction; RH: Relative Humidity; RPE: Rate of Perceived Exertion; SD: Standard Deviation; SEM: Sensor Electronics Module; Tcore: Core Body Temperature; Tbody: Mean Body Temperature; Tskin: Mean Skin Temperature; TS: Thermal Sensation; VO2max: Maximal Oxygen Uptake.Highlights The pathophysiology of exertional-heat stroke is widely hypothesised to be at least in part attributable to a systemic inflammatory response caused by the leak of gastrointestinal microbes into the circulating blood.Acute high-dose (0.9 g kg FFM-1) L-glutamine supplementation is widely promoted as a practical strategy to protect gastrointestinal barrier integrity during exertional-heat stress. However, previously validated doses are often poorly tolerated and cannot be recommended for widespread implementation.This study examined the efficacy of low-dose (0.30 g kg FFM-1; ∼20 grams) acute L-glutamine supplementation on small intestinal injury, permeability, and microbial translocation in response a high-intensity exertional-heat stress test to exhaustion (20-30 min). This type of exercise accounts for the majority of exertional-heat stroke cases in the military.Despite being universally well-tolerated across all participants, acute low-dose L-glutamine supplementation worsened gastrointestinal permeability, without influencing either small intestinal injury or microbial translocation. These findings do not support the application of low-dose L-glutamine supplementation to help prevent exertional-heat stroke.

Available evidence indicates that elevated blood ketones are associated with improved hypoxic tolerance in rodents. From this perspective, we hypothesized that exogenous ketosis by oral intake of the ketone ester ( R)-3-hydroxybutyl ( R)-3-hydroxybutyrate (KE) may induce beneficial physiological effects during prolonged exercise in acute hypoxia. As we recently demonstrated KE to deplete blood bicarbonate, which per se may alter the physiological response to hypoxia, we evaluated the effect of KE both in the presence and absence of bicarbonate intake (BIC). Fourteen highly trained male cyclists performed a simulated cycling race (RACE) consisting of 3-h intermittent cycling (IMT180′) followed by a 15-min time-trial (TT15′) and an all-out sprint at 175% of lactate threshold (SPRINT). During RACE, fraction of inspired oxygen ([Formula: see text]) was gradually decreased from 18.6% to 14.5%. Before and during RACE, participants received either 1) 75 g of ketone ester (KE), 2) 300 mg/kg body mass bicarbonate (BIC), 3) KE + BIC, or 4) a control drink in addition to 60 g of carbohydrates/h in a randomized, crossover design. KE counteracted the hypoxia-induced drop in blood ([Formula: see text]) and muscle oxygenation by ∼3%. In contrast, BIC decreased [Formula: see text] by ∼2% without impacting muscle oxygenation. Performance during TT15′ and SPRINT were similar between all conditions. In conclusion, KE slightly elevated the degree of blood and muscle oxygenation during prolonged exercise in moderate hypoxia without impacting exercise performance. Our data warrant to further investigate the potential of exogenous ketosis to improve muscular and cerebral oxygenation status, and exercise tolerance in extreme hypoxia.

Study design Cross-sectional cohort study. Objectives To compare ratings of perceived exertion (RPE) on Borg’s 6–20 RPE scale and Category Ratio 10 (CR10) in able-bodied (AB) participants during upper and lower body exercise, and recreationally active participants with paraplegia (PARA) and athletes with tetraplegia (TETRA) during upper body exercise only. Setting University and rehabilitation centre-based laboratories in UK and Netherlands. Methods Twenty-four participants were equally split between AB, PARA, and TETRA. AB performed maximal tests using cycle (AB-CYC) and handcycle (AB-HC) ergometry. PARA and TETRA performed maximal handcycle and wheelchair propulsion tests, respectively. Oxygen uptake (V̇O2) and blood lactate concentration were monitored throughout. RPE was rated each stage on Borg’s RPE scale and CR10. Thresholds were identified according to log-V̇O2 plotted against log-blood lactate (LT1), and 1.5 mmol L−1 greater than LT1 (LT2). Results RPE from both scales were best fit against each other using a quadratic model, with high goodness of fit between scales that was independent of exercise mode and participant group (range R2: 0.965–0.970, P 2 was significantly greater in TETRA (P 1 or LT2 between groups on Borg’s RPE scale or CR10. Conclusion Strong association between Borg’s RPE scale and CR10 suggests they can be used interchangeably. RPE at lactate thresholds were independent of mode of exercise and level of spinal cord injury. However, inter-individual variation precludes from making firm recommendations about using RPE for prescribing homogenous exercise intensity.

Background. Obstetric hemorrhage is the leading cause of maternal mortality worldwide. According to the World Health Organization, massive bleeding in parturient women, along with infectious complications and preeclampsia, determine up to 75 % of cases of maternal mortality. The purpose of the study was to identify prognostic markers in clinical decision making for massive blood transfusions in parturient women with blood loss. Materials and methods. The study included 38 parturient women in whom childbirth was complicated by blood loss. The average age of the subjects was 27.4 ± 4.1 years, weight — 83.3 ± 4.8 kg. The number of first-time mothers was 18 patients (47.4 %), multipara — 20 mothers (52.6 %). Postpartum blood loss averaged 1,830.5 ± 622.7 ml. All bleedings were stopped according to current protocols. Results. The analysis showed that indicators such as the level of fibrinogen (p = 0.0223) and lactate (p = 0.0137) had statistical differences in the study groups with massive blood transfusions and moderate blood transfusions. One-dimensional logistic regression analysis gave an odds ratio of 0.95 (95% confidence interval (CI), 0.96–0.98) for fibrinogen and 1.7 (95% CI, 1.1–3.14) for lactate, and an odds ratio for shock index was 1.45 (95% CI, 0.46–4.52). The area under the ROC-curves (AUC) for fibrinogen, lactate and shock index was 0.805 (95% CI, 0.612–0.927), 0.722 (95% CI, 0.528–0.869) and 0.588 (95% CI, 0.381–0.780), respectively. The limit value of fibrinogen 2.13 g/l had a sensitivity and specificity of 0.91 and 0.55, respectively. At the same time, the limit value of lactate, equal to 4 mmol/l, had a sensitivity and specificity of 0.69 and 0.66, respectively. AUC for lactate was significantly higher than for shock index, the difference in AUC between these indicators was –0.134 (95% CI, 0.275 to –0.012) (p = 0.052). The lactate threshold of 4 mmol/l had a sensitivity and specificity of 0.69 and 0.66, respectively, while the threshold for the shock index of 1.2 had a sensitivity and specificity of 0.64 and 0.35, respectively. Conclusions. Lactate was a better prognostic marker in the clinical decision to conduct massive blood transfusions, compared with the generally accepted shock index in patients with postpartum blood loss. Lactate measurement may be useful for activating the massive blood transfusions protocol and for promoting the onset of active hemostasis procedures.

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...

Prior constant-load exercise performed for 30-min at or above maximal lactate steady state (MLSSp) significantly impairs subsequent time-to-task failure (TTF) compared with TTF performed without prior exercise. We tested the hypothesis that TTF would decrease in relation to the intensity and the duration of prior exercise compared with a baseline TTF trial. Eleven individuals (6 males, 5 females, aged 28 ± 8 yrs) completed the following tests on a cycle ergometer (randomly assigned after MLSSp was determined): (i) a ramp-incremental test; (ii) a baseline TTF trial performed at 80% of peak power (TTFb); (iii) five 30-min constant-PO rides at 5% below lactate threshold (LT−5%), halfway between LT and MLSSp (Delta50), 5% below MLSSp (MLSS−5%), MLSSp, and 5% above MLSSp (MLSS+5%); and (iv) 15- and 45-min rides at MLSSp (MLSS15 and MLSS45, respectively). Each condition was immediately followed by a TTF trial at 80% of peak power. Compared with TTFb (330 ± 52 s), there was 8.0 ± 24.1, 23.6 ± 20.2, 41.0 ± 14.8, 52.2 ± 18.9, and 75.4 ± 7.4% reduction in TTF following LT−5%, Delta50, MLSS−5%, MLSSp, and MLSS+5%, respectively. Following MLSS15 and MLSS45 there were 29.0 ± 20.1 and 69.4 ± 19.6% reductions in TTF, respectively (P < 0.05). It is concluded that TTF is reduced following prior exercise of varying duration at MLSSp and at submaximal intensities below MLSS. Novelty: Prior constant-PO exercise, performed at intensities below MLSSp, reduces subsequent TTF performance. Subsequent TTF performance is reduced in a linear fashion following an increase in the duration of constant-PO exercise at MLSSp.

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 r = .92–.95, P

Introduction Obesity is a condition that generally limits work capacity and predisposes to a number of comorbidities and related diseases, the last being COVID-19 and its complications and sequelae. Physical exercise, together with diet, is a milestone in its management and rehabilitation, although there is still a debate on intensity and duration of training. Anaerobic threshold (AT) is a broad term often used either as ventilatory threshold or as lactate threshold, respectively, detected by respiratory ventilation and/or respiratory gases (VCO2 and VO2), and by blood lactic acid. Aims and methodology This review outlines the role of AT and of the different variations of growth hormone and catecholamine, in subjects with obesity vs normal weight individuals below and beyond AT, during a progressive increase in exercise training. We present a re-evaluation of the effects of physical activity on body mass and metabolism of individuals with obesity in light of potential benefits and pitfalls during COVID-19 pandemic. Comparison of a training program at moderate-intensity exercise ( AT) exercise at the end of the aerobic session will be discussed. Results Based on our data and considerations, a tailored strategy for individuals with obesity concerning the most appropriate intensity of training in the context of rehabilitation is proposed, with special regard to potential benefits of work program above AT. Conclusion Adding bouts of exercise above AT may improve lactic acid and H+ disposal and improve growth hormone. Long-term aerobic exercise may improve leptin reduction. In this way, the propensity of subjects with obesity to encounter a serious prognosis of COVID-19 may be counteracted and the systemic and cardiorespiratory sequelae that may ensue after COVID-19, can be overcome. Individuals with serious comorbidities associated with obesity should avoid excessive exercise intensity.

The purpose of this study was to verify the effectiveness of the rate of perceived exertion threshold (RPET) for predicting young competitive swimmers’ lactate threshold (LT) during incremental testing. We enrolled 13 male athletes ( M age = 16, SD = 0.6 years) in an incremental test protocol consisting of eight repetitions of a 100-meter crawl with 2-minute intervals between each repetition. We collected data for blood lactate concentration ([La]) and Borg scale rate of perceived exertion (RPE) at the end of each repetition. The results obtained were: M RPET = 4.98, SD = 1.12 arbitrary units (A.U.) and M lactate threshold = 4.24, SD = 1.12 mmol.L−1, with [La] and RPE identified by the maximal deviation (Dmax) method without a significant difference ( p > 0.05) and large correlations between DmaxLa and DmaxRPE at variables for time (r = 0.64), velocity (r = 0.67) and percentage of personal best time (PB) (r = 0.60). These results suggest that RPET is a good predictor of LT in young competitive swimmers.

Aims:\ud \ud Heart failure with reduced ejection fraction (HFrEF) induces skeletal muscle mitochondrial abnormalities that contribute to exercise limitation; however, specific mitochondrial therapeutic targets remain poorly established. This study quantified the relationship and contribution of distinct mitochondrial respiratory states to prognostic whole‐body measures of exercise limitation in HFrEF.\ud \ud \ud \ud Methods and results:\ud \ud Male patients with HFrEF (n = 22) were prospectively enrolled and underwent ramp‐incremental cycle ergometry cardiopulmonary exercise testing to determine exercise variables including peak pulmonary oxygen uptake (V̇O2peak), lactate threshold (V̇O2LT), the ventilatory equivalent for carbon dioxide (V̇E/V̇CO2LT), peak circulatory power (CircPpeak), and peak oxygen pulse. Pectoralis major was biopsied for assessment of in situ mitochondrial respiration. All mitochondrial states including complexes I, II, and IV and electron transport system (ETS) capacity correlated with V̇O2peak (r = 0.40–0.64; P < 0.05), V̇O2LT (r = 0.52–0.72; P < 0.05), and CircPpeak (r = 0.42–0.60; P < 0.05). Multiple regression analysis revealed that combining age, haemoglobin, and left ventricular ejection fraction with ETS capacity could explain 52% of the variability in V̇O2peak and 80% of the variability in V̇O2LT, respectively, with ETS capacity (P = 0.04) and complex I (P = 0.01) the only significant contributors in the model.\ud \ud \ud \ud Conclusions:\ud \ud Mitochondrial respiratory states from skeletal muscle biopsies of patients with HFrEF were independently correlated to established non‐invasive prognostic cycle ergometry cardiopulmonary exercise testing indices including V̇O2peak, V̇O2LT, and CircPpeak. When combined with baseline patient characteristics, over 50% of the variability in V̇O2peak could be explained by the mitochondrial ETS capacity. These data provide optimized mitochondrial targets that may attenuate exercise limitations in HFrEF.

Optimal active recovery is 80% of lactate threshold for trained individuals, yet this may differ for untrained individuals. Therefore, our goal was to investigate the lactate response during optimal active recovery for athletes vs. non-athletes. Sixteen adults (21 ± 1 year, BMI: 26.5 ± 3.6 kg·m−2) were enrolled in a cohort study (collegiate athletes vs. non-athletes). Visit one determined participant lactate threshold and VO2max. Visit two consisted of a brief, but intense running protocol followed by active recovery at 80% of lactate threshold. Heart rate and lactate were taken at rest and every four minutes during active recovery. General mixed linear modeling was used (Alpha p

The efficacy of high-intensity interval training (HIIT) to elicit physiological and performance adaptations in endurance athletes has been established in men and to a lesser extent in women. This study compared lactate threshold (LT2) and performance adaptations to HIIT between men and women. Nine male and eight female cyclists and triathletes completed trials to determine their LT2 and 40 km cycling performance before, and after 10 HIIT sessions. Each HIIT session consisted of 10 × 90 s at peak power output, separated by 60 s active recovery. Main effects showed that HIIT improved peak power output (p = 0.05; ES: 0.2); relative peak power output (W.kg-1; p = 0.04; ES: 0.3 and W.kg-0.32; p = 0.04; ES: 0.3); incremental time to fatigue (p = 0.01; ES: 0.4), time trial time (p < 0.001; ES: 0.7) and time trial power output (p < 0.001; ES: 0.7) equally in both sexes. Although LT2 power output explained 77% of the performance improvement in women, no variable explained the performance improvement in men, suggesting another mechanism(s) was involved. Although HIIT improved cycling performance in men and women, it might not be appropriate to evaluate the effectiveness of HIIT using the same variables for both sexes.

Current study aimed to establish percentile normative data and to find age differences in fitness performance tests of 14–19-year-old footballers played in a Greek elite youth football academy. A total of 216 male players from four different chronological age groups of the same club, from under 15 to under 19 (U-15, U16, U17 & U-19) for 5 consecutive years (2014–2018) who played in six different positions — as midfielders, defenders, wingbacks, wingers, forwards, and goalkeepers — participated in the study, with 426 measurements. Measured variables of weight, height, body mass index (BMI), squat jump (SJ), countermovement jump test (CMJ), countermovement jump test with arm swing (CMJAS) isokinetic strength peak torque (PT) ratio of hamstring (H) and quadriceps (Q) at speed of 60°·s−1, sit & reach test (i.e., flexibility), aerobic maximal exercise test on a treadmill to exhaustion (VO2max), and velocity at VO2max were recorded and compared among age groups during the period 2014–2018. Age and performance physical fitness parameters values (i.e., P3 to P97) were generated using Box–Cox power transformations. The elite footballers had mean age of 15.6 ± 1.4 years, body weight 66.7 ± 7.8 kg, height 1.757 ± 0.064 cm and BMI 21.6 ± 1.7 kg·m−2. Performance across all testing variables was increased according to age, with each age scoring higher/better than their younger counterparts from the U-15 squad up. Velocity at lactate threshold (VLth-Km/h) was 13.6, 13.4, 13.1, and 13.2 Km/h, for the four age groups respectively, and 203.5, 201.9, 187.8, and 177.4 Nm in extension of left quadriceps in 60°·s−1 peak torque, Q (Nm). Moreover, the U-19 presented superior performance in VO2max (Vvo2max) to the other age categories (18.2, 17.9, 17.4, and 17.3 km/h, respectively). Footballers’ flexibility and jump ability were more developed in U-19 age group compared with other group ages. Findings indicated that U-19 players performed better than younger players in all assessments. This may have been possible due to the differences in training experience, and individual levels of strength/power/endurance ability. Moreover, establishing normative performance values will allow practitioners to more accurately identify deficiencies in performance that are relative to their athletes.

Wearable exercise trackers provide data that encode information on individual running performance. These data hold great potential for enhancing our understanding of the complex interplay between training and performance. Here we demonstrate feasibility of this idea by applying a previously validated mathematical model to real-world running activities of ≈ 14,000 individuals with ≈ 1.6 million exercise sessions containing duration and distance, with a total distance of ≈ 20 million km. Our model depends on two performance parameters: an aerobic power index and an endurance index. Inclusion of endurance, which describes the decline in sustainable power over duration, offers novel insights into performance: a highly accurate race time prediction and the identification of key parameters such as the lactate threshold, commonly used in exercise physiology. Correlations between performance indices and training volume and intensity are quantified, pointing to an optimal training. Our findings hint at new ways to quantify and predict athletic performance under real-world conditions., Laboratory performance tests provide the gold standard for running performance but do not reflect real running conditions. Here the authors use a large, real world dataset obtained from wearable exercise trackers to extract parameters that accurately predict race times and correlate with training.

PURPOSE: We recently reported that oral ketone ester (KE) intake before and during the initial 30 min of a 3 h 15 min simulated cycling race (RACE) transiently decreased blood pH and bicarbonate without affecting maximal performance in the final quarter of the event. We hypothesized that acid-base disturbances due to KE overrules the ergogenic potential of exogenous ketosis in endurance exercise. METHODS: Nine well-trained male cyclists participated in a similar RACE consisting of 3 h submaximal intermittent cycling (IMT180') followed by a 15-min time trial (TT15') preceding an all-out sprint at 175% of lactate threshold (SPRINT). In a randomized crossover design, participants received (i) 65 g KE, (ii) 300 mg·kg-1 body weight NaHCO3 (BIC), (iii) KE + BIC, or (iv) a control drink (CON), together with consistent 60 g·h-1 carbohydrate intake. RESULTS: KE ingestion transiently elevated blood D-ß-hydroxybutyrate to ~2-3 mM during the initial 2 h of RACE (P < 0.001 vs CON). In KE, blood pH concomitantly dropped from 7.43 to 7.36 whereas bicarbonate decreased from 25.5 to 20.5 mM (both P < 0.001 vs CON). Additional BIC resulted in 0.5 to 0.8 mM higher blood D-ß-hydroxybutyrate during the first half of IMT180' (P < 0.05 vs KE) and increased blood bicarbonate to 31.1 ± 1.8 mM and blood pH to 7.51 ± 0.03 by the end of IMT180' (P < 0.001 vs KE). Mean power output during TT15' was similar between KE, BIC, and CON at ~255 W but was 5% higher in KE + BIC (P = 0.02 vs CON). Time to exhaustion in the sprint was similar between all conditions at ~60 s (P = 0.88). Gastrointestinal symptoms were similar between groups. DISCUSSION: The coingestion of oral bicarbonate and KE enhances high-intensity performance at the end of an endurance exercise event without causing gastrointestinal distress. ispartof: Medicine And Science In Sports And Exercise vol:53 issue:2 pages:431-441 ispartof: location:United States status: published

NEW FINDINGS What is the central question of this study? Do haemoglobin mass and red blood cell volume increase in elite cyclists training in a hot environment compared to a control group training at normal temperature? What is the main finding and its importance? Five weeks of heat training increases haemoglobin mass in elite cyclists. There are small to intermediate effect sizes for exercise parameters favouring heat training. ABSTRACT In this study we tested the hypothesis that performing 1 h of regular light exercise in a heat chamber (HEAT; 37.8 ± 0.5°C; 65.4 ± 1.8% humidity) 5 times week-1 for a total of 5 weeks increases haemoglobin mass (Hbmass ) and exercise performance in elite cyclists ( VO2max = 76.2 ± 7.6 ml min-1 kg-1 ). Twenty-three male volunteers were assigned to HEAT (n = 11) or CON (n = 12; 15.5 ± 0.1°C; 25.1 ± 0.0% humidity) training groups. Hbmass was determined before and after the intervention period in conjunction with an extensive exercise test protocol (conducted at 16-19°C). HEAT increased (P

Purpose To characterise the physiological profiles of trained handcyclists, during recumbent handcycling, to describe the physiological responses during a 16 km time trial (TT) and to identify the determinants of this TT performance. Methods Eleven male handcyclists performed a sub-maximal and maximal incremental exercise test in their recumbent handbike, attached to a Cyclus II ergometer. A physiological profile, including peak aerobic power output (POPeak), peak rate of oxygen uptake ($$\dot{V}$$V˙O2Peak), aerobic lactate threshold (AeLT) and PO at 4 mmol L−1 (PO4), were determined. Participants also completed a 16 km simulated TT using the same experimental set-up. Determinants of TT performance were identified using stepwise multiple linear regression analysis. Results Mean values of POPeak = 252 ± 9 W, $$\dot{V}$$V˙O2Peak = 3.30 ± 0.36 L min−1 (47.0 ± 6.8 mL kg−1 min−1), AeLT = 87 ± 13 W and PO4 = 154 ± 14 W were recorded. The TT was completed in 29:21 ± 0:59 min:s at an intensity equivalent to 69 ± 4% POPeak and 87 ± 5% $$\dot{V}$$V˙O2Peak. POPeak (r = − 0.77, P = 0.006), PO4 (r = − 0.77, P = 0.006) and AeLT (r = − 0.68, P = 0.022) were significantly correlated with TT performance. PO4 and POPeak were identified as the best predictors of TT performance (r = 0.89, P Conclusion POPeak, PO4 and AeLT are important physiological TT performance determinants in trained handcyclists, differentiating between superior and inferior performance, whereas $$\dot{V}$$V˙O2peak was not. The TT took place at an intensity corresponding to 69% POPeak and 87% $$\dot{V}$$V˙O2peak.

This study aims to investigate the biomechanics of handcycling during a continuous load trial (CLT) to assess the mechanisms underlying fatigue in upper body exercise. Twelve able-bodied triathletes performed a 30-min CLT at a power output corresponding to lactate threshold in a racing recumbent handcycle mounted on a stationary ergometer. During the CLT, ratings of perceived exertion (RPE), tangential crank kinetics, 3D joint kinematics, and muscular activity of ten muscles of the upper extremity and trunk were examined using motion capturing and surface electromyography. During the CLT, spontaneously chosen cadence and RPE increased, whereas crank torque decreased. Rotational work was higher during the pull phase. Peripheral RPE was higher compared to central RPE. Joint range of motion decreased for elbow-flexion and radial-duction. Integrated EMG (iEMG) increased in the forearm flexors, forearm extensors, and M. deltoideus (Pars spinalis). An earlier onset of activation was found for M. deltoideus (Pars clavicularis), M. pectoralis major, M. rectus abdominis, M. biceps brachii, and the forearm flexors. Fatigue-related alterations seem to apply analogously in handcycling and cycling. The most distal muscles are responsible for force transmission on the cranks and might thus suffer most from neuromuscular fatigue. The findings indicate that peripheral fatigue (at similar lactate values) is higher in handcycling compared to leg cycling, at least for inexperienced participants. An increase in cadence might delay peripheral fatigue by a reduced vascular occlusion. We assume that the gap between peripheral and central fatigue can be reduced by sport-specific endurance training.

Purpose Most studies with cancer survivors use percentages of peak oxygen uptake (VO2peak) for intensity prescription. Lactate or ventilatory thresholds might be useful submaximal alternatives, but this has never been investigated. Therefore, we aimed at comparing three training sessions prescribed using %VO2peak (reference), lactate thresholds, and ventilatory thresholds in terms of meeting the vigorous-intensity zone, physiological, and psychological responses. Methods Twenty breast (58 ± 10 years) and 20 prostate cancer survivors (68 ± 6 years), 3.6 ± 2.4 months after primary therapy, completed a maximal cardiopulmonary exercise test and three vigorous training sessions in randomized order: 38 min of cycling at 70% VO2peak (M-VO2peak), 97% of individual anaerobic lactate threshold (M-IAT), and 67% between ventilatory thresholds 1 and 2 (M-VT). Heart rate (HR), blood lactate concentration (bLa), perceived exertion, and enjoyment were assessed. Results Cancer survivors exercised at 75 ± 23, 85 ± 18, and 79 ± 19 W during M-VO2peak, M-IAT, and M-VT (p > .05). Sessions could not be completed in 3, 8, and 6 cases. Session completers showed HR of 82 ± 7, 83 ± 9, and 84 ± 8 %HRpeak and bLa of 3.7 ± 1.9, 3.9 ± 0.9, and 3.9 ± 1.5 mmol·l−1, which was not different between sessions (p > .05). However, variance in bLa was lower in M-IAT compared to M-VO2peak (p = .001) and to M-VT (p = .022). Conclusion All intensity prescription methods on average met the targeted intensity zone. Metabolic response was most homogeneous when using lactate thresholds. Implications for cancer survivors Submaximal thresholds are at least as useful as VO2peak for intensity prescription in cancer survivors. Overall, slightly lower percentages should be chosen to improve durability of the training sessions.

Objectives: Aviation Rescue Firefighters (ARFF) require physical fitness specific to the aviation environment. This study aims to determine the physical fitness of ARFF and predictors of performance on ARFF-specific tasks from laboratory-based fitness measures. Design: Cross-sectional, observational study. Methods: Forty-two male ARFF (mean ± SD; age 38.4 ± 7.6 years, body mass index 26.2 ± 2.2 kg m−2) completed a physical fitness testing battery, comprising maximal aerobic capacity (), lactate threshold, anaerobic power, body composition (dual-energy X-ray absorptiometry), muscular strength (3 repetition maximum (3RM) bench and leg press) and muscular endurance (maximum curl ups and push ups) under controlled laboratory conditions. On a separate occasion, ARFF completed timed work-related tasks including a hose drag, dummy drag, Stihl saw hold, stair climb and simulated ARFF emergency protocol. Results: All participants finished the simulated ARFF emergency protocol under the criterion time (5 min 50 s); the average completion time was 4 min and 31 s. Performance time on the simulated ARFF emergency protocol was inversely correlated to (r = −0.514; p < 0.001), anaerobic step test performance (r = −0.549; p < 0.001), height (r = −0.325; p = 0.038) and lean mass (r = −0.429; p = 0.005). Higher fat mass (r = 0.318; p = 0.043) and % body fat (r = 0.481; p = 0.001) were associated with slower performance time. Muscular strength, muscular endurance and flexibility were not related to performance on the simulated ARFF emergency protocol. Conclusions: Aerobic and anaerobic capacities, as well as body composition are the strongest predictors of simulated ARFF emergency protocol performance. This study highlights the importance of aerobic and anaerobic fitness, compared to muscular strength or muscular endurance, for ARFF job-specific performance, employment and training.

Burnsed-Torres, ML, Wichmann, TK, Clayton, ZS, and Hahn, ME. Comparison of the Gauntlet test with standard laboratory measures of aerobic fitness. J Strength Cond Res XX(X): 000-000, 2019-The purpose of this study was to validate whether the Gauntlet test (GT) can accurately estimate individual aerobic endurance performance compared with standard laboratory-based physiological tests. The GT required athletes to complete 5 maximal effort running stages, with a 1-minute break between each stage, with the goal of achieving the best overall time. Eighteen men (n = 9) and women (n = 9) (age, 23.5 ± 4.13 years; body mass index, 23.1 ± 7.62 kg·m; 5k time, 22 ± 7 minutes; 10k time, 47 ± 15 minutes; V[Combining Dot Above]O2max, 52.3 ± 8 ml·kg·min) completed a lactate threshold test and V[Combining Dot Above]O2max test (laboratory measures). Four to 14 days later, subjects completed the GT on an outdoor track. Blood lactate (bLa), V[Combining Dot Above]O2max, and heart rate (HR) were recorded during the laboratory session. Blood lactate, HR, stage completion time, and overall completion time were recorded during the GT. Linear regression correlation analyses revealed a significant inverse association between V[Combining Dot Above]O2max (mL·kg·min) and GT completion time (r = -0.88, P < 0.0001). In addition, there were significant correlations between V[Combining Dot Above]O2max maximum HR and GT maximum HR (r = 0.89, P < 0.0001) and V[Combining Dot Above]O2max 3-minute post bLa and GT 3-minute post bLa (r = 0.63, P = 0.0029). Sex-specific analysis showed significant inverse associations between female and male GT completion time and V[Combining Dot Above]O2max (r = -0.70, P = 0.0352; r = -0.94, P < 0.0002). Bland-Altman plots were used to evaluate concordance between GT completion time, V[Combining Dot Above]O2max, maximum HR, and 3-minute post bLa. Results suggest the GT is a valid assessment to accurately estimate aerobic endurance performance similar to standard laboratory methods.

BACKGROUND The phenomenon of exercise-induced hypoalgesia and concomitant mood changes is well-established. How exercise-induced hypoalgesia and affective responses are shaped by the intensity of an acute exercise bout and individual fitness levels is as yet not well-understood. This study investigates whether heat pain threshold (PTh), pain tolerance (PTol) and affective parameters are modulated by the intensity of an acute exercise bout and/or individuals' fitness level. Stronger analgesic responses are hypothesized after high-intensity exercise in physically fitter subjects, possibly in sync with concomitant mood changes. METHODS Thirty-three healthy men were recruited (sedentary: N = 17 or recreational: N = 14; mean age: 25.3 ± 4.4 years). After a fitness assessment on a cycle ergometer, subjects underwent three experimental conditions on separate days: high (20 min exercise 20% above lactate threshold), low (20 min exercise 20% below lactate threshold) and control (seated rest). Before and after each intervention Positive and Negative Affect Schedule, PTh and PTol (cold water emersion test) were assessed. RESULTS Results indicate an increase of the Positive Affect Scale (high: 26.7 ± 9.0 vs. 32.9 ± 7.1, p

Aim. To determine whether the skeletal muscle of patients with chronic heart failure (CHF) retains the ability to regenerate and grow; to compare the effectiveness of long aerobic trainings, calculated by an individualized method, and conventionally calculated trainings (VO 2 peak values), in relation to the severity of heart failure, exercise tolerance (ET), and ergoreflex activity (ERGO). Material and methods . The study included 297 patients with stable III functional class (FC) CHF, receiving optimal therapy. The presence of heart failure was found in all patients at least 6 months before the start of the study (age — 18-65 years, body mass index (BMI) — 19-28 kg/height, m 2 . Initially, the study performed a cardiorespiratory test (CRT) with an assessment of gas composition, acid-base balance of the blood and ERGO activity. Patients were randomized into 2 groups: experimental (EG) and control (CG). For EG, based on the determination of the lactate threshold (LT), after 1 and 3 months the CRT was repeated and the training walking mode was dynamically recounted according to the new LT level. For CG, the training walking mode was calculated based on the VO2peak values. All patients trained for 6 months. At the end of the training, diagnostic CRT was performed, and the activity of EGO was evaluated. Eleven patients with CHF and 3 healthy donors before the start of the training underwent a biopsy of the gastrocnemius muscle. Results. It was shown that the potential for muscle differentiation of satellite skeletal muscle precursor cells obtained from patients with CHF with a reduced ejection fraction (HFrEF) does not differ in vitro from the potential of satellite cells of healthy donors. After 6 months of training, the severity of CHF decreased to FC II in 75% of EG patients, and among CG patients — in 44%; the main indicators of the stages of compensatory mechanisms activation during physical exertion (VO 2 LT and VO 2 peak) in EG increased more than in the CG (10,8±0,4, 18,7±0,7 ml/min/kg and 9,5±0,8, 15,3±0,9 ml/min/kg, with p 1

Physical activity could play a key role in improving the quality of life, particularly in patients with nervous system diseases such as multiple sclerosis (MS). Through lactacid anaerobic training, this study aims to investigate the effects at a bio-psycho-physical level to counteract the chronic fatigue associated with the pathology, and to improve mental health at a psychological and neurotrophic level. Eight subjects (age: 34.88 ± 4.45 years) affected by multiple sclerosis were involved. A lactate threshold training program was administered biweekly for 12 weeks at the beginning of the study (T0), at the end of the study (T1) and at 9 months after the end of the study (T2), with physical, psychological and hematochemicals parameters, and dietary habits being tested. The results obtained confirmed that lactacid exercise can influence brain-derived neurotrophic factor (BDNF) levels as well as dehydroepiandrosterone sulfate (DHEAS) levels. In addition, levels of baseline lactate, which could be best used as an energy substrate, showed a decrease after the protocol training. Self-efficacy regarding worries and concerns management significantly increased from T0 to T1. The eating attitudes test (EAT-26) did not highlight any eating disease in the patients with a normal diet enrolled in our study. Physical exercise also greatly influenced the patients psychologically and emotionally, increasing their self-esteem. Lactate threshold training, together with dietary habits, appears to exert synergic positive effects on inflammation, neural plasticity and neuroprotection, producing preventive effects on MS symptoms and progression.

Background and Objectives: This study aimed to compare the calculated running velocity at the anaerobic lactate threshold (cLTAn), determined by a mathematical model for metabolic simulation, with two established threshold concepts (onset of blood lactate accumulation (OBLA, 4 mmol∙L−1) and modified maximal deviation method (mDmax)). Additionally, all threshold concepts were correlated with performance in different endurance running events. Materials and Methods: Ten sub-elite runners performed a 30 s sprint test on a cycle ergometer adjusted to an isokinetic mode set to a cadence of 120 rpm to determine maximal lactate production rate (VLamax), and a graded exercise test on a treadmill to determine maximal oxygen uptake (VO2max). Running velocities at OBLA, mDmax, and cLTAn were then compared with each other, and further correlated with running performance over various distances (3000 m, 5000 m, and 10,000 m). Results: The mean difference in cLTAn was −0.13 ± 0.43 m∙s−1 and −0.32 ± 0.39 m∙s−1 compared to mDmax (p = 0.49) and OBLA (p &lt, 0.01), respectively. cLTAn indicated moderate to good concordance with the established threshold concepts (mDmax: ICC = 0.87, OBLA: ICC = 0.74). In comparison with other threshold concepts, cLTAn exhibited comparable correlations with the assessed running performances (cLTAn: r = 0.61–0.76, mDmax: r = 0.69–0.79, OBLA: r = 0.56–0.69). Conclusion: Our data show that cLTAn can be applied for determining endurance performance during running. Due to the consideration of individual physiological profiles, cLTAn offers a physiologically justified approach to assess an athlete’s endurance performance.

This study aimed to analyze the effects of live high-train low method (LH-TL) and intermittent hypoxic training (IHT) with a controlled mixed diet on lipid profile in cyclists. Thirty trained male cyclists at a national level with at least six years of training experience participated in the study. The LH-TL group was exposed to hypoxia (FiO2 = 16.5%) for 11–12 h a day and trained under normoxia for 3 weeks. In the IHT group, participants followed the IHT routine three times a week under hypoxia (FiO2 = 16.5%) at lactate threshold intensity. The control group (N) lived and trained under normoxia. The results showed that the 3-week LH-TL method significantly improved all lipid profile variables. The LH-TL group showed a significant increase in HDL-C by 9.0% and a decrease in total cholesterol (TC) by 9.2%, LDL-C by 18.2%, and triglycerides (TG) by 27.6%. There were no significant changes in lipid profiles in the IHT and N groups. ∆TG and ∆TC were significantly higher in the LH-TL group compared to the N group. In conclusion, hypoxic conditions combined with a mixed diet can induce beneficial changes in lipid profile even in highly trained athletes. The effectiveness of the hypoxic stimulus is closely related to the hypoxic training method.

Aim Observed effects of exercise are highly variable between individuals, and subject‐by‐training interaction (i.e., individual response variability) is often not estimated. Here, we measured mitochondrial (citrate synthetase, cytochrome‐c oxidase, succinate dehydrogenase, and mitochondrial copy‐number), performance markers (W peak, lactate threshold [LT], and VO2peak), and fiber type proportions/expression (type I, type IIa, and type IIx) in multiple time points during 12‐week of high‐intensity interval training (HIIT) to investigate effects of exercise at the individual level. Methods Sixteen young (age: 33.1 ± 9.0 years), healthy men (VO2peak 35–60 ml/min/kg and BMI: 26.4 ± 4.2) from the Gene SMART study completed 12‐week of progressive HIIT. Performance markers and muscle biopsies were collected every 4 weeks. We used mixed‐models and bivariate growth models to quantify individual response and to estimate correlations between variables. Results All performance markers exhibited significant (W peak 0.56 ± 0.33 p = 0.003, LT 0.37 ± 0.35 p = 0.007, VO2peak 3.81 ± 6.13 p = 0.02) increases overtime, with subject‐by‐training interaction being present (95% CI: W peak 0.09–0.24, LT 0.06–0.18, VO2peak 0.27–2.32). All other measurements did not exhibit significant changes. Fiber type IIa proportions at baseline was significantly associated with all physiological variables (p, Exercise training leads to whole body and tissue‐specific adaptations. However, the observed effects of exercise are highly variable between individuals, and subject‐by‐training interaction (i.e., individual response variability) is often not estimated. Here, we measured mitochondrial (citrate synthetase, cytochrome‐c oxidase, succinate dehydrogenase and mitochondrial copy‐number), performance markers (W peak, lactate threshold, and VO2peak) and fiber type proportions/expression (type I, type IIa, and type IIx) in multiple time points during 12‐week of high‐intensity interval training to investigate effects of exercise at the individual level, and if measurement changes in different domains covary each other as exercise goes by.

Knowledge in the scientific domain of individual medley (IM) swimming training over a competitive season is limited. The purpose of this study was to propose a detailed coaching framework incorporating the key elements of a periodized training regimen for a 400 m IM swimmer. This framework was based on the available coaching and scientific literature and the practical experience and expertise of the collaborating authors. The season has been divided in two or three macrocycles, further divided in three mesocycles each (six or nine mesocycles in total), in alignment with the two or three main competitions in each macrocycle. The principal training contents to develop during the season expressed in blood lactate zones are: aerobic training (~2 mmol·L−1), lactate threshold pace (~4 mmol·L−1) and VO2max (maximum oxygen uptake) (~6 mmol·L−1). Strength training should focus on maximum strength, power and speed endurance during the season. Altitude training camps can be placed strategically within the training season to promote physiological adaptation and improvements in performance. A well-constructed technical framework will permit development of training strategies for the 400 m IM swimmer to improve both training and competitive performance.

This study examined the effect of altered body weight (BW) and body fat content on exercise performance and recovery. Nine horses were divided into two groups, and changes in BW and fat content were induced by feeding a high (HA) or restricted (RA) energy allowance for 36 days in a cross‐over design. In the last week of each treatment, BW and body condition score (BCS) were recorded, body fat percentage was estimated using ultrasound, and a standardized incremental treadmill exercise test (SET) and competition‐like field test were performed (scored by judges blinded to treatments). Blood samples were collected, and heart rate (HR), rectal temperature (RT), and respiratory rate (RR) were also recorded. Objective locomotion analyses were performed before and after the field test. Body weight, body fat percentage, and BCS were higher (5–8%) in HA than in RA horses (p, The results clearly show that increased BW and body fat content in horses lower physiological fitness in terms of VLa4, plasma lactate removal, Hct levels, plasma glucose availability and reduce true performance evaluated by blinded judges. Higher body fat content and BW alter metabolic and physiological responses to exercise by more than could be expected from increased weight load alone and it also cause locomotion asymmetry.

PURPOSE: We recently demonstrated that coingestion of NaHCO3 to counteract ketoacidosis resulting from oral ketone ester (KE) intake improves mean power output during a 15-min time trial (TT) at the end of a 3-h cycling race by ~5%. This ergogenic effect occurred at a time when blood ketone levels were low, as ketosis was only induced during the initial ~2 h of the race. Therefore, in the current study, we investigated whether performance also increases if blood ketone levels are increased in the absence of ketoacidosis during high-intensity exercise. METHODS: In a double-blind crossover design, 14 well-trained male cyclists completed a 30-min TT (TT30') followed by an all-out sprint at 175% of lactate threshold (SPRINT). Subjects were randomized to receive (i) 50 g KE, (ii) 180 mg·kg-1 body weight NaHCO3 (BIC), (iii) KE + BIC, or (iv) a control drink (CON). RESULTS: KE ingestion increased blood d-ß-hydroxybutyrate to ~3-4 mM during the TT30' and SPRINT (P < 0.001 vs CON). In KE, blood pH and bicarbonate concomitantly dropped, causing 0.05 units lower pH and 2.6 mM lower bicarbonate in KE compared with CON during the TT30' and SPRINT (P < 0.001 vs CON). BIC coingestion resulted in 0.9 mM higher blood d-ß-hydroxybutyrate (P < 0.001 vs KE) and completely counteracted ketoacidosis during exercise (P > 0.05 vs CON). Mean power output during TT30' was similar between CON and BIC at 281 W, but was 1.5% lower in the KE conditions (main effect of KE: P = 0.03). Time to exhaustion in the SPRINT was ~64 s in CON and KE and increased by ~8% in the BIC conditions (main effect of BIC: P < 0.01). DISCUSSION: Neutralization of acid-base disturbance by BIC coingestion is insufficient to counteract the slightly negative effect of KE intake during high-intensity exercise. ispartof: Medicine And Science In Sports And Exercise vol:53 issue:5 pages:1-41 ispartof: location:United States status: Published online

This investigation aimed to determine the effect of a multi-ingredient pre-workout supplement (MIPS) on heart rate (HR), perceived exertion (RPE), lactate concentration, and time to fatigue (TTF) during a running task to volitional exhaustion. Eleven NCAA Division I cross-country runners (20 ± 2 year, height: 171 ± 14 cm, weight: 63.5 ± 9.1 kg) participated in this randomized, double-blind, placebo-controlled cross-over study. Bayesian statistical methods were utilized, and parameter estimates were interpreted as statistically significant if the 95% highest-density intervals (HDIs) did not include zero. TTF was increased in the MIPS condition with a posterior Meandiff = 154 ± 4.2 s (95% HDI: −167, 465) and a 0.84 posterior probability that the supplement would increase TTF relative to PL. Blood lactate concentration immediately post-exercise was also higher in the MIPS condition compared to PL with an estimated posterior Meandiff = 3.99 ± 2.1 mmol (95% HDI: −0.16, 7.68). There were no differences in HR or RPE between trials. These findings suggest that a MIPS ingested prior to sustained running at lactate threshold has an 84% chance of increasing TTF in highly trained runners and may allow athletes to handle a higher level of circulating lactate before reaching exhaustion.

Purpose: To examine whether an ecologically valid, intermittent, sprint-based warm-up strategy impacted the ergogenic capacity of individualized sodium bicarbonate (NaHCO3) ingestion on 4-km cycling time-trial (TT) performance. Methods: A total of 8 male cyclists attended 6 laboratory visits for familiarization, determination of time to peak blood bicarbonate, and 4 × 4-km cycling TTs. Experimental beverages were administered doubleblind. Treatments were conducted in a block-randomized, crossover order: intermittent warm-up + NaHCO3 (IWSB), intermittent warm-up + placebo, control warm-up + NaHCO3 (CWSB), and control warm-up + placebo (CWP). The intermittent warm-up comprised exercise corresponding to lactate threshold (5 min at 50%, 2 min at 60%, 2 min at 80%, 1 min at 100%, and 2 min at 50%) and 3 × 10-second maximal sprints. The control warm-up comprised 16.5 minutes cycling at 150 W. Participants ingested 0.3 g·kg body mass−1 NaHCO3 or 0.03 g·kg body mass−1 sodium chloride (placebo) in 5 mL·kg body mass−1 fluid (3:2, water and sugar-free orange squash). Paired t tests were conducted for TT performance. Hematological data (blood bicarbonate and blood lactate) and gastrointestinal discomfort were analyzed using repeated-measures analysis of variance. Results: Performance was faster for CWSB versus IWSB (5.0 [6.1] s; P = .052) and CWP (5.8 [6.0] s; P = .03). Pre-TT bicarbonate concentration was elevated for CWSB versus IWSB (+9.3 mmol·L−1; P −1; P −1; P = .022). Belching was exacerbated pre-warm-up for IWSB versus intermittent warm-up +placebo (P = .046) and CWP (P = .027). Conclusion: An intermittent, sprint-based warm-up mitigated the ergogenic benefits of NaHCO3 ingestion on 4-km cycling TT performance.

Purpose: The aims of this study were to analyze the physical functions of swimmers and the effects of altitude training through the blood physiological and biochemical tests during the altitude training and comparing individual lactate threshold testing before and after the altitude training, respectively. Methods: Eight elite swimmers took a 26-day altitude training session. The individual lactate threshold test was carried out by the Swedish Monak839E power cycle progressive loading method before and after the training. During the altitude training period, 5 ml of blood of the subjects’ elbow vein was extracted and tested on an empty stomach and in a quiet state every Monday morning. Results: There is no obvious difference in the hemoglobin between the plain and plateau when swimmers first reached. In the second week, the hemoglobin value showed a significant downward trend both in males and in females. The hemoglobin value in the third week has increased significantly and is higher than the level when swimmers first entered the plateau. During altitude training, the serum testosterone value of males and females showed different trends. Compared with the first week, the second and third weeks have a significant weekly upward trend. From the changes of creatine kinase in male swimmers, the highest value of creatine kinase was 731 U/L in the first week and fluctuated within the normal range in the following two weeks. The creatine kinase of female swimmers fluctuated within the normal range of three weeks. There is no obvious change in individual lactate threshold before and after altitude training for both male and female swimmers. Conclusions: The altitude training has generally improved the swimmers’ training ability, however, based on factors such as training years and gender, individualized training programs need to be targeted according to each swimmer’s situation, to achieve better performance.

Objective Cardiopulmonary exercise testing (CPET) is often used to assess pre‐operative fitness in elderly patients, in whom peripheral arterial disease (PAD) is highly prevalent, but may affect the results of CPET by early lactate release due to muscle ischemia. This study investigated the effect revascularization of PAD on oxygen delivery (VO2) during CPET. Method We conducted a prospective cohort study of 30 patients, who underwent CPET before and after treatment of ilio‐femoral PAD. The primary outcome measure was difference in VO2 at the lactate threshold (LT) before and after revascularization. Secondary outcome measures were the relationship between change in VO2 at LT and peak exercise and change in ankle–brachial index (ABI) differential. Results The study was approved by the North West‐Lancaster Research and Ethics committee (reference 15/NW/0801) and registered in clinicaltrial.gov (reference NCT02657278). As specified in the study protocol, 30 patients were recruited but only 20 (15 men), with a mean age of 62 years, completed pre‐ and post‐treatment CPETs. Twelve patients demonstrated an improvement in VO2 at LT after revascularization, but the difference did not achieve statistical significance (mean difference (95% CI) = 1.43 (−0.21 to 3.08) ml/kg/min; (p = 0.085). There was, however, a significant improvement in VO2, VE/CO2, workload and Borg breathlessness and leg fatigue score at peak exercise after revascularization. There was no significant correlation between change in VO2 at LT (r = −0.11, p = 0.65) or change in VO2 at peak and ABI differential (r = −0.14, p = 0.55). Conclusion Revascularization of PAD led to significant improvement in multiple peak/maximal exercise parameters within a few weeks and without exercise training. We were unable to demonstrate a statistically significant improvement in VO2 at LT albeit in a majority of subjects this exceeded what we pre‐defined as clinically significant., The study suggests that the presence of peripheral artery disease may affect measured oxygen delivery during cardiopulmonary test. Clinical interpretation of this test may need to take into account the presence of occlusive arterial disease of the lower limbs if these results are confirmed.

This review explores recent advances in the etiology of exercise intolerance (classically defined by a reduced maximal or peak oxygen uptake) in lowlanders at high altitudes, focussing on sites of physiological-system limitation and how these may differ in highlanders. The traditional opinion of impaired oxygen delivery along a convective-diffusive cascade between lungs and exercising-muscle mitochondria remains relevant but an oversimplification. Thus, developments in genomics, proteomics and metabolomics are providing an exciting, expanded perspective of exercising-muscle function. However, factors such as ascent profile, altitude sojourn, training status, ethnicity, genetics and development present interpretational challenges. Also, while animal models can be useful proxies for human function because they allow a greater degree of invasive interrogation, species differences can limit their applicability. Finally, assessment of exercise performance at altitude requires rigorous application of exercise intensity, through key demarcators such as the lactate threshold, critical power and W′ — each of which are altitude-dependent.

Cross-sectional studies have found a correlation between the duration or volume of moderate-to-vigorous physical activity (MVPA) and steps per day (STEP), but there is little information on why this relationship varies among individuals. No previous research has established whether STEP can be used to estimate the duration of physical activity (PA) at or above lactate threshold (≥LT), such as for maintaining cardiorespiratory fitness. This study explored the association among STEP, MVPA indices, and ≥LT under free-living conditions. Seventy young adult women measured their PA for 7 days using a validated accelerometer. The mean LT measured by an exercise test was 5.8 ± 1.0 METs. STEP, MVPA, METs×h, and ≥LT were 9324 ± 2677 steps/day, 231.9 ± 101.5 min/week, 16.6 ± 7.4 METs×h/week and 24.0 ± 22.2 min/week, respectively. Significant correlations were found between STEP and MVPA duration and between STEP and METs×h/week (r = 0.81 and r = 0.81); however, approximately 1600 steps/day of the standard error of estimates in the regression equations were found. Multiple stepwise regression analysis revealed that the percentage of total time spent at light-intensity PA (LPA) and MVPA were significant determinants of the percent deviation of STEP from the linear relationships between STEP and MVPA indices. No significant relationship was observed between ≥LT and STEP. The association between STEP and MVPA fluctuated depending on individual daily LPA and MVPA. Thus, consideration of both STEP and the PA at specific intensities are necessary to ensure the PA guidelines are met and the health benefits gained. STEP alone would be not a sufficient indicator for assessing the ≥LT.

A review of protocols and staging of cardiopulmonary exercise testing (CPET) used in clinical practice is done in the article. CPET is proposed to assess the functional status and to diagnose early reserve abnormalities in patients with sarcoidosis as far as functional tests at rest are mostly insufficient in sarcoidosis. Physiological processes at anaerobic threshold at peak exercise are described in the article. The authors reviewed current approach to terminology and determination of anaerobic threshold, methods for calculation of cut-off points and their clinical role. Diagnostic values of CPET parameters, such as maximal and peak oxygen uptake and oxygen consumption ratio, parameters of gas exchange and ventilation, such as ventilatory equivalent, breathing reserve, alveolar-arterial gradient in oxygen, and ventilation-perfusion ratio, in patients with sarcoidosis were also discussed.

Acute exercise reduces renal blood flow (RBF). However, the effect of exercise intensity on RBF in patients with chronic kidney disease (CKD) stage 2 is not known. We investigated the association between RBF and exercise intensity in patients with CKD stage 2 using pulsed Doppler ultrasonography. Eight men with CKD stage 2 (cystatin C-based estimate of glomerular filtration rate: 60–89 ml/min/1.73 m2) participated in this study. Using a bicycle ergometer, participants undertook a maximal graded exercise test (MGET) (experiment 1) and a multi-stage exercise test (experiment 2) to determine their lactate threshold (LT). Participants undertook a multi-stage exercise test for 4-min each. Workloads of 60%, 80%, 100%, 120%, and 140% of LT were used in experiment 3. RBF was measured by pulsed Doppler ultrasonography at rest, immediately after exercise, and 1 h after exercise in experiment 1, and at rest and immediately after each exercise bout in experiment 3. Renal blood flow after the MGET was 52% lower than at rest, and did not recover as well as after the exercise test. Cross-sectional area (CSA) was significantly lower after graded exercise. RBF tended to be lower at 100% of LT and was significantly lower at 120% of LT. CSA was significantly lower at 100% of LT. Renal blood flow does not change during exercise until the LT is reached. These findings may assist in making appropriate exercise recommendations to patients with CKD stage 2.

[Purpose] The purpose of this study was to investigate the effect of diet plus exercise training and detraining for 12 weeks on body composition, aerobic performance, and stress-related variables in obese women. [Methods] Twenty-five women in their 20s-40s with 30% body fat and body mass indices above 25 kg/m2 were divided into HRLT (heart rate at lactate threshold) and HRLT + 5% groups. Dietary intervention of 70% recommended dietary allowance (RDA) and exercise treatment composed of aerobic exercises on a bicycle (30 min) and treadmill (30 min) were then performed. These interventions were performed three times a week for 12 weeks. [Results] Dietary intake was significantly decreased, while daily activity significantly increased within the 12- week intervention period, and this effect was sustained after 12 weeks of detraining. Exercise training based on dietary intake and daily activity presented a significantly decreased weight and % body fat, improvement of aerobic performance, and a significant increase in heart rate variability (HRV) (e.g., average of all RR intervals and the square root mean squared differences of successive RR intervals) as stress-related variables. It was also confirmed that the improvement of body composition and stress-related variables were maintained even after detraining. [Conclusion] Our results suggest that 70% RDA of dietary intervention and exercise training corresponding to HRLT and HRLT + 5% for 12 weeks were effective in improving body composition and aerobic performance, and relieving stress. In particular, enhanced HRV persisted for up to 12 weeks after the end of exercise training in obese women.

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 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%.

Exercise stimulates the release of inflammatory cytokines and supplementation with n-3 fatty acids reduces inflammation. The effects of different doses of docosahexaenoic acid (DHA) on inflammation in polo horses submitted to field lactate threshold tests (LT) were analyzed. We hypothesized that higher doses of DHA would reduce postexercise inflammation. Twenty polo horses were assigned to different treatments: control group fed (n = 5) grain and hay, 3 treatment groups (n = 5) fed 10, 20, or 50 g/day of DHA with grain and free choice hay during 60 days. Horses underwent LT tests before start, 30, and 60 days of supplementation. Blood samples were taken at rest for blood cytokine expression (CEx), plasma cytokine enzyme-linked immunosorbent assay (CEL), fatty acid, vitamin E, and creatine kinase (CK) analysis, after LT for CEx analysis (interferon gamma, tumor necrosis factor alpha [TNF-α], interleukin-1 [IL-1], interleukin-6 [IL-6], interleukin-10 [IL-10]), CEL, and CK analysis. Effects of treatment, time, and exercise were analyzed by analysis of variance, significant results compared by least square means analysis, and significance set at P.05. There was a dose-dependent increase in plasma DHA, and highest arachidonic acid was found in 20 and 50 g. Vitamin E was lowest in 20 and 50 g. LT did not change IL-6, downregulated IL-1 and TNF-α, upregulated IL-10, and interferon gamma. The 10 g led to postexercise downregulation of interferon gamma and IL-10 CEx compared to other treatments. A lack of antioxidants in the supplements may have led to the absence of treatment effects in the 20 and 50 g. 10 g DHA helped moderate postexercise inflammation.

Made available in DSpace on 2019-10-05T04:10:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-12-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Few data exist on the physiological consequences of an incremental exercise test (IET) and training in dogs. Here we evaluated the effect of an endurance-training program (ETP) on the kinetics of the serum biomarkers: creatine kinase (CK), aspartate aminotransferase (AST), myoglobin, cardiac troponin I (cTnI), and creatine kinase isoenzyme MB (CK-MB). Eighteen Beagle dogs were assigned to three groups: sedentary (S), untrained (U), and trained (T). The dogs from the groups T and U underwent IET, and their lactate threshold (LT) was determined. The LT and velocity corresponding to the LT (VLT) was determined by visual inspection. The VLT was utilized to determine the training intensity level. Thus, the dogs from group T underwent an eight-week aerobic conditioning program with the intensity training set to 70-80% of the VLT. Next, dogs from the groups T and U have submitted to IET again. The group S did not undergo IETs or training. The maximal velocity (Vmax) at which the dog achieves in the IET and heart rate were determined. For biomarkers, venous blood samples were collected before the experimental procedure (baseline) and before and 1, 6, 12, 24, 48, and 72 h after the IETs. VLT and Vmax increased in group T (P < .05), indicating an improvement in dogs' aerobic and anaerobic fitness. CK and AST rose (P < .05), peaking 6 h after both IETs and returning to baseline levels after 12-24 h. Levels of cTnI and myoglobin were unaltered. CK-MB peaked 1 h after the IETs and returned to baseline levels after 12 h (P < .05). We concluded that ETP improved the aerobic capacity of the dogs without any skeletal or cardiac muscle injury. Sao Paulo State Univ UNESP, Sch Agr & Veterinarian Sci, BR-14884900 Jaboticabal, SP, Brazil Sao Paulo State Univ UNESP, Sch Agr & Veterinarian Sci, BR-14884900 Jaboticabal, SP, Brazil FAPESP: 2013/00449-8

Summary The aim of the present study was to examine whether the exercise intensity corresponding to the lactate threshold may be predicted by the Maximum Phonation Time task (MPT). Ten Greek amateur football players (age: 18.4 ± 1.0 years), performed a graded cycling exercise test to exhaustion in order to determine lactate threshold. A number of physiological variables were measured including perceived exertion, cardiopulmonary values and blood lactate. The MPT variable was correlated with all of the physiological variables. Also, a binary logistic regression analysis was used to investigate whether MPT could predict lactate threshold. The ROC analysis showed specificity to be 0.90 and sensitivity to be 0.70 (optimal screening cutoff point for MPT 9.5 seconds). The results showed an odds ratio of 1.45 indicating a 45% increase in the probability of passing the threshold for every second there was a reduction in voice duration. MPT may be used as a simple, non-invasive, inexpensive method for monitoring exercise intensity during physical exercise. Further research is needed to measure its efficacy in bigger samples and in different sports.

The lactate threshold (LT1), which is defined as the first rise in lactate concentration during incremental exercise, has not been non-invasively and conveniently determined in a clinical setting. We aimed to visualize changes in lactate concentration in sweat during exercise using our wearable lactate sensor and investigate the relationship between the lactate threshold (LT1) and ventilatory threshold (VT1). Twenty-three healthy subjects and 42 patients with cardiovascular diseases (CVDs) were enrolled. During exercise, the dynamic changes in lactate values in sweat were visualized in real-time with a sharp continuous increase up to volitional exhaustion and a gradual decrease during the recovery period. The LT1 in sweat was well correlated with the LT1 in blood and the VT1 (r = 0.92 and 0.71, respectively). In addition, the Bland–Altman plot described no bias between the mean values (mean differences: − 4.5 and 2.5 W, respectively). Continuous monitoring of lactate concentrations during exercise can provide additional information for detecting the VT1.

The current study aimed to investigate the effect of the relative CHO content in a pre-event meal on time to exhaustion (TTE), peak oxygen uptake (V∙O2peak), the 2nd lactate threshold (LT2), onset of blood lactate accumulation (OBLA), and work economy (WE) and to compare responses between well-trained and recreationally trained individuals. Eleven well-trained and 10 recreationally trained men performed three trials in a randomized cross-over design, in which they performed exercise tests (1) after a high-CHO pre-event meal (3 g · kg−1), (2) a low-CHO pre-event meal (0.5 g · kg−1), or (3) in a fasted-state. The test protocol consisted of five submaximal 5-min constant-velocity bouts of increasing intensity and a graded exercise test (GXT) to measure TTE. A repeated measure ANOVA with a between-subjects factor (well-trained vs. recreational) was performed. A main effect of pre-event meal was found (p = 0.001), with TTE being 8.0% longer following the high-CHO meal compared to the fasted state (p = 0.009) and 7.2% longer compared to the low-CHO meal (p = 0.010). No significant effect of pre-event meal on V∙O2peak, LT2, OBLA, or WE (p ≥ 0.087) was found and no significant interaction effect between training status and pre-event CHO intake was found for TTE or any of the performance-determining variables (p ≥ 0.257). In conclusion, high-CHO content in the pre-event meal led to a longer TTE compared to a meal with a low-CHO content or exercising in a fasted state, both in well-trained and recreationally trained participants. However, the underlying physiological reason for the increased TTE is unclear, as no effect of pre-event meal on the main physiological performance-determining variables was found. Thus, pre-event CHO intake should be standardized when the goal is to assess endurance performance but seems to be of less importance when assessing the main performance-determining variables.

International audience; The use of endurance regimens could be improved by defining their respective effectiveness on aerobic fitness and brain health that remains controversial. We aimed at comparing work-matched high-intensity interval training (HIIT) with moderate-intensity continuous training (MICT) on aerobic performance and muscular plasticity markers in healthy rats. Cognitive functions and brain plasticity markers were also investigated following the 8-week training. Rats performed the incremental exercise test and behavioural tests before and after training at day 1 (D1), D15, D29 and D57. Key cerebral markers were assessed by Western blot and quantitative polymerase chain reaction to provide information on brain function related to angiogenesis, aerobic metabolism and neurotrophin activity at D59. Muscular protein levels involved in angiogenesis and aerobic metabolism were measured in both triceps brachii and soleus muscles. HIIT induced superior improvement of aerobic fitness compared to MICT, as indicated by enhancement of speed associated with lactate threshold (SLT) and maximal speed (Smax). In the triceps brachii muscle, markers of angiogenesis and aerobic activity were upregulated as well as myokines involved in neuroplasticity. Moreover, levels of key brain plasticity markers increased in the hippocampus after 8 weeks of HIIT, without improving cognitive functions. These findings might contribute to define physical exercise guidelines for maintaining brain health by highlighting the promising role of HIIT when using SLT for distinguishing low running speed from high running speed. Further studies are required to confirm these brain effects by exploring synaptic plasticity and neurogenesis mechanisms when exercise intensity is standardized and individualized.

We investigated whether horses trained in moderate and mild hypoxia demonstrate greater improvement in performance and aerobic capacity compared to horses trained in normoxia and whether the acquired training effects are maintained after 2 weeks of post‐hypoxic training in normoxia. Seven untrained Thoroughbred horses completed 4 weeks (3 sessions/week) of three training protocols, consisting of 2‐min cantering at 95% maximal oxygen consumption V˙O2max under two hypoxic conditions (H16, F IO2 = 16%; H18, F IO2 = 18%) and in normoxia (N21, F IO2 = 21%), followed by 2 weeks of post‐hypoxic training in normoxia, using a randomized crossover study design with a 3‐month washout period. Incremental treadmill tests (IET) were conducted at week 0, 4, and 6. The effects of time and groups were analyzed using mixed models. Run time at IET increased in H16 and H18 compared to N21, while speed at V˙O2max was increased significantly only in H16. V˙O2max in all groups and cardiac output at exhaustion in H16 and H18 increased after 4 weeks of training, but were not significantly different between the three groups. In all groups, run time, V˙O2max, VV˙O2max, Q˙max, and lactate threshold did not decrease after 2 weeks of post‐hypoxic training in normoxia. These results suggest that 4 weeks of training in moderate (H16), but not mild (H18) hypoxia elicits greater improvements in performance and running economy than normoxic training and that these effects are maintained for 2 weeks of post‐hypoxic training in normoxia., The present study demonstrates that 4 weeks of training in moderate (F IO2 = 16%), but not mild hypoxia (F IO2 = 18%) was sufficient to elicit greater improvements in performance and running economy than normoxic training and that the effects of the hypoxic training were maintained over 2 weeks of post‐hypoxic training. Although trainers should monitor weight loss, our results can give a new insight into hypoxic training in horses and provide a new strategy for training programs in Thoroughbred racehorses.

Particulate generation occurs during exercise-induced exhalation, and research on this topic is scarce. Moreover, infection-control measures are inadequately implemented to avoid particulate generation. A laminar airflow ventilation system (LFVS) was developed to remove respiratory droplets released during treadmill exercise. This study aimed to investigate the relationship between the number of aerosols during training on a treadmill and exercise intensity and to elucidate the effect of the LFVS on aerosol removal during anaerobic exercise. In this single-center observational study, the exercise tests were performed on a treadmill at Running Science Lab in Japan on 20 healthy subjects (age: 29±12 years, men: 80%). The subjects had a broad spectrum of aerobic capacities and fitness levels, including athletes, and had no comorbidities. All of them received no medication. The exercise intensity was increased by 1-km/h increments until the heart rate reached 85% of the expected maximum rate and then maintained for 10 min. The first 10 subjects were analyzed to examine whether exercise increased the concentration of airborne particulates in the exhaled air. For the remaining 10 subjects, the LFVS was activated during constant-load exercise to compare the number of respiratory droplets before and after LFVS use. During exercise, a steady amount of particulates before the lactate threshold (LT) was followed by a significant and gradual increase in respiratory droplets after the LT, particularly during anaerobic exercise. Furthermore, respiratory droplets ≥0.3 μm significantly decreased after using LFVS (2120800±759700 vs. 560 ± 170, p