Training the inspiratory muscles improves running performance when carrying a 25 kg thoracic load in a backpack

Load carriage (LC) exercise in physically demanding occupations is typically characterised by periods of low-intensity steady-state exercise and short duration, high-intensity exercise while carrying an external mass in a backpack; this form of exercise is also known as LC exercise. This induces inspiratory muscle fatigue and reduces whole-body performance. Accordingly we investigated the effect of inspiratory muscle training (IMT, 50% maximal inspiratory muscle pressure (P_Imax) twice daily for six week) upon running time-trial performance with thoracic LC. Nineteen healthy males formed a pressure threshold IMT (n?=?10) or placebo control group (PLA; n?=?9) and performed 60?min LC exercise (6.5?km?h^–1) followed by a 2.4?km running time trial (LC_TT) either side of a double-blind six week intervention. Prior to the intervention, P_Imax was reduced relative to baseline, post-LC and post-LC_TT in both groups (pooled data: 13?±?7% and 16?±?8%, respectively, p?P_Imax increased +31% (p?TT (+18%, p?P_Imax at each time point was unchanged (13?±?11% and 17?±?9%, respectively, p?>?.05). In IMT only, heart rate and perceptual responses were reduced post-LC (p?p?相似文献   

Impact of carbohydrate mouth rinsing on time to exhaustion during Ramadan: A randomized controlled trial in Jordanian men

Mouth rinsing using a carbohydrate (CHO) solution has been suggested to improve physical performance in fasting participants. This study examined the effects of CHO mouth rinsing during Ramadan fasting on running time to exhaustion and on peak treadmill speed (V_peak). In a counterbalanced crossover design, 18 sub-elite male runners (Age: 21?±?2 years, Weight: 68.1?±?5.7?kg, VO_2max: 55.4?±?4.8?ml/kg/min) who observed Ramadan completed a familiarization trial and three experimental trials. The three trials included rinsing and expectorating a 25?mL bolus of either a 7.5% sucrose solution (CHO), a flavour and taste matched placebo solution (PLA) for 10?s, or no rinse (CON). The treatments were performed prior to an incremental treadmill test to exhaustion. Three-day dietary and exercise records were obtained on two occasions and analysed. Anthropometric characteristics were obtained and recorded for all participants. A main effect for mouth rinse on peak velocity (V_peak) (CHO: 17.6?±?1.5?km/h; PLA: 17.1?±?1.4?km/h; CON: 16.7?±?1.2?km/h; P?η_p²?=?0.49) and time to exhaustion (CHO: 1282.0?±?121.3?s; PLA: 1258.1?±?113.4?s; CON: 1228.7?±?98.5?s; P?=?.002, η_p²?=?0.41) was detected, with CHO significantly higher than PLA (P?P?P?>?.05). Energy availability from dietary analysis, body weight, and fat-free mass did not change during the last two weeks of Ramadan (P?>?.05). This study concludes that carbohydrate mouth rinsing improves running time to exhaustion and peak treadmill speed under Ramadan fasting conditions.     

Larger strength losses and muscle activation deficits in plantar flexors induced by backward downhill in reference to distance-matched forward uphill treadmill walk

We tested the hypothesis that backward downhill walking (eccentric component) impairs both voluntary activation and muscle contractile properties in the plantar flexors and delays recovery as compared to a gradient and distance-matched uphill walk. Fourteen males performed two 30-min walking exercises (velocity: 1?m/?s; grade: 25%; load: 12% of body weight), one downhill (DW) and one uphill (UP), in a counterbalanced order, separated by 6?weeks. Neuromuscular test sessions were performed before, after, 24-, 48- and 72-h post-exercise, including motor nerve stimulations during brief (5?s) and sustained (1?min) maximal isometric voluntary contractions of the plantar flexors. DW (?18.1?±?11.1%, P?P?=.15), decreased torque production during brief contractions for at least three days post-exercise (P?P?P?=?.024) and DW (?25.6?±?10.3%, P?P?=?.001) was lower in DW than UP. Peak twitch torque and maximum rates of torque development and relaxation were equally reduced after UP and DW (P?P?P?>?.05). Using a direct comparison, the capacity to drive the plantar flexors during sustained contractions remains sub-optimal during the three-day recovery period in response to non-exhaustive, downhill backward walking in reference to an uphill exercise matched for distance covered.     

Time of day and short-duration high-intensity exercise influences on coagulation and fibrinolysis

Exercise has been demonstrated to have considerable effects upon haemostasis, with activation dependent upon the duration and intensity of the exercise bout. In addition, markers of coagulation and fibrinolysis have been shown to possess circadian rhythms, peaking within the morning (0600–1200?h). Therefore, the time of day in which exercise is performed may influence the activation of the coagulation and fibrinolytic systems. This study aimed to examine coagulation and fibrinolytic responses to short-duration high-intensity exercise when completed at different times of the day. Fifteen male cyclists (VO_2max: 60.3?±?8.1?ml?kg^?1?min^?1) completed a 4-km cycling time trial (TT) on five separate occasions at 0830, 1130, 1430, 1730 and 2030. Venous blood samples were obtained pre- and immediately post-exercise, and analysed for tissue factor (TF), tissue factor pathway inhibitor (TFPI), thrombin–anti-thrombin complexes (TAT) and D-Dimer. Exercise significantly increased plasma concentrations of TF (p?p?p?p?p?=?.004) and TFPI (p?=?.031), with 0830 greater than 1730 (p .001), while 1730 was less than 2030?h (p?=?.008), respectively. There was no significant effect of time of day for TAT (p?=?.364) and D-Dimer (p?=?.228). Power output, TT time and heart rate were not significantly different between TTs (p?>?.05); however, percentage VO_2max was greater at 1730 when compared to 2030 (p?=?.04). Due to a time-of-day effect present within TF, peaking at 0830, caution should be applied when prescribing short-duration high-intensity exercise bout within the morning in populations predisposed to hypercoagulability.     

Effects of a phase change cooling garment during exercise in the heat

The purpose of our study was to examine the physiological, perceptual, and performance effects of wearing a phase change cooling garment (CG) during an interval exercise routine in the heat. Sixteen male participants (age 23?±?3 years, ht 1.76?±?0.11?m; wt 78.5?±?11.2?kg; body fat 15.2?±?5.8%) completed two trials (one with phase change inserts, CG, and one control without inserts) consisting of two submaximal exercise portions separated by 5-minute seated rest, and a final maximal effort performance bout. Each submaximal bout involved 30?seconds or 1?minute of muscular endurance and agility exercises and 5?minutes of treadmill jogging and step-ups. The performance bout included 30?seconds or 1?minute of muscular endurance and agility exercises, with participants completing as many repetitions as possible, followed by a 15-minute recovery (active and passive). Rectal temperature (T_re) and heart rate were not different between trials, however change in T_re from baseline was improved during 10 and 15 minutes of recovery with the CG (P?<?.05). Mean skin temperature was lower using the CG vs control throughout the trial (P?<?.05). Thermal sensation was lower when using the CG compared to control (P?<?.001). There were no differences in any outcomes of the performance exercises (P?>?.05). These findings indicate that the continuous use of a CG during an interval style workout in the heat provides improvements in thermal sensation, however, only minimal thermophysiological benefits, and no performance augmentation.     

Effects of whey protein in carbohydrate-electrolyte drinks on post-exercise rehydration

The purpose of this study was to examine the effects of different amounts of whey protein in carbohydrate–electrolyte (CE) drinks on post-exercise rehydration. Ten males completed 5 trials in a randomised cross-over design. A 4-h recovery was applied after a 60-min run at 65% VO_2peak in each trial. During recovery, the participants ingested a high-carbohydrate CE drink (CE-H), a low-carbohydrate CE drink (CE-L), a high-whey-protein (33?g·L^?1) CE drink (CW-H), a medium-whey-protein (22?g·L^?1) CE drink (CW-M) or a low-whey-protein (15?g·L^?1) CE drink (CW-L) in a volume equivalent to 150% of their body mass (BM) loss. The drinks were provided in six equal boluses and consumed by the participants within 150?min in each trial. After exercise, a BM loss of 2.15%?±?0.05% was achieved. Urine production was less in the CW-M and CW-H trials during recovery, which induced a greater fluid retention in the CW-M (51.0%?±?5.7%) and CW-H (55.4%?±?3.8%) trials than in any other trial (p?p?p?p??1 in the current study.     

The exercise intensity at maximal oxygen uptake (i⩒O2max): Methodological issues and repeatability

The minimum exercise intensity that elicits ?O_2max (i?O_2max) is an important variable associated with endurance exercise performance. i?O_2max is usually determined during a maximal incremental exercise test; however, the magnitude and duration of the increments used influence the i?O_2max value produced by a given test. The aims of this study were twofold. The first was to investigate whether the i?O_2max value produced by a single cycle ergometer test (i?O_2max(S)) was repeatable. The second was to determine if i?O_2max(S) represents the minimum intensity at which ?O_2max is elicited when compared to a refined i?O_2max value (i?O_2max(R)) derived from repeated tests. Seventeen male cyclists (age 33.9?±?7.7 years, body mass 80.9?±?10.2?kg, height 1.82?±?0.05?m; VO_2max 4.27?±?0.62 L?min^?1) performed four maximal incremental tests for the determination of i?O_2max(S) and i?O_2max(R) (3 min stages; 20?W increments). Trials 1 and 2 were identical and used for assessing the repeatability of i?O_2max(S), trials 3 and 4 began at different intensities and were used to determine i?O_2max(R). i?O_2max(S) showed good test–retest repeatability for i?O_2max (CV?=?4.1%; ICC?=?0.93), VO_2max (CV?=?6.3%; ICC?=?0.88) and test duration (CV?=?6.7%; ICC?=?0.89). There was no significant difference between i?O_2max(S) and i?O_2max(R) (303?±?40?W vs. 301?±?42?W) (P?2max determined directly during a maximal incremental test is repeatable and provides a very good estimate of the minimum exercise intensity that elicits ?O_2max.     

High-intensity interval and moderate-intensity continuous training elicit similar enjoyment and adherence levels in overweight and obese adults

Background: High-intensity interval training (HIIT) has been shown to improve cardiometabolic health during supervised lab-based studies but adherence, enjoyment, and health benefits of HIIT performed independently are yet to be understood. We compared adherence, enjoyment, and cardiometabolic outcomes after 8 weeks of HIIT or moderate-intensity continuous training (MICT), matched for energy expenditure, in overweight and obese young adults. Methods: 17 adults were randomized to HIIT or MICT. After completing 12 sessions of supervised training over 3 weeks, participants were asked to independently perform HIIT or MICT for 30 min, 4 times/week for 5 weeks. Cardiometabolic outcomes included cardiorespiratory fitness (VO₂ peak), lipids, and inflammatory markers. Exercise enjoyment was measured by the validated Physical Activity Enjoyment Scale. Results: Exercise adherence (93.4?±?3.1% vs. 93.1?±?3.7%, respectively) and mean enjoyment across the intervention (100.1?±?4.3 vs. 100.3?±?4.4, respectively) were high, with no differences between HIIT and MICT (p?>?.05). Similarly, enjoyment levels did not change over time in either group (p?>?.05). After training, HIIT exhibited a greater decrease in low-density lipoprotein cholesterol than MICT (?0.66?mmol?L^?1 vs. ?0.03?mmol?L^?1, respectively) and a greater increase in VO₂ peak than MICT (p?<?.05, +2.6?mL?kg?min^?1 vs. +0.4?mL?kg?min^?1, respectively). Interleukin-6 and C-reactive protein increased in HIIT (+0.5?pg?mL^?1 and +?31.4?nmol?L^?1, respectively) and decreased in MICT (?0.6?pg?mL^?1 and ?6.7?nmol?L^?1, respectively, p?<?.05). Conclusions: Our novel findings suggest that HIIT is enjoyable and has high unsupervised adherence rates in overweight and obese adults. However, HIIT may be associated with an increase in inflammation with short-term exercise in this population.     

Thermoneutral immersion exercise accelerates heart rate recovery: A potential novel training modality

This study compared heart rate recovery (HRR) after incremental maximal exercise performed at the same external power output (P_ext) on dry land ergocycle (DE) vs. immersible ergocycle (IE). Fifteen young healthy participants (30?±?7 years, 13 men and 2 women) performed incremental maximal exercise tests on DE and on IE. The initial P_ext on DE was 25?W and was increased by 25?W/min at a pedalling cadence between 60 and 80?rpm, while during IE immersion at chest level in thermoneutral water (30°C), the initial P_ext deployment was at a cadence of 40?rpm which was increased by 10?rpm until 70?rpm and thereafter by 5?rpm until exhaustion. Gas exchange and heart rate (HR) were measured continuously during exercise and recovery for 5?min. Maximal HR (DE: 176?±?15 vs. IE 169?±?12?bpm) reached by the subjects in the two conditions did not differ (P?>?.05). Parasympathetic reactivation parameters (ΔHR from 10 to 300?s) were compared during the DE and IE HR recovery recordings. During the IE recovery, parasympathetic reactivation in the early phase was more predominant (HRR at Δ10–Δ60?s, P?<?.05), but similar in the late phase (HRR at Δ120–Δ300?s, P?>?.05) when compared to the DE condition. In conclusion, incremental maximal IE exercise at chest level immersion in thermoneutral water accelerates the early phase parasympathetic reactivation compared to DE in healthy young participants.     

Interval running with self-selected recovery: Physiology,performance, and perception

This study (1) compared the physiological responses and performance during a high-intensity interval training (HIIT) session incorporating externally regulated (ER) and self-selected (SS) recovery periods and (2) examined the psychophysiological cues underpinning SS recovery durations. Following an incremental maximal exercise test to determine maximal aerobic speed (MAS), 14 recreationally active males completed 2 HIIT sessions on a non-motorised treadmill. Participants performed 12?×?30?s running intervals at a target intensity of 105% MAS interspersed with 30?s (ER) or SS recovery periods. During SS, participants were instructed to provide themselves with sufficient recovery to complete all 12 efforts at the required intensity. A semi-structured interview was undertaken following the completion of SS. Mean recovery duration was longer during SS (51?±?15?s) compared to ER (30?±?0?s; p?d?=?1.46?±?0.46). Between-interval heart rate recovery was higher (SS: 19?±?9?b?min^?1; ER: 8?±?5?b?min^?1; p?d?=?1.43?±?0.43) and absolute time ≥90% maximal heart rate (HR_max) was lower (SS: 335?±?193?s; ER: 433?±?147?s; p?=?.075; d?=?0.52?±?0.39) during SS compared to ER. Relative time ≥105% MAS was greater during SS (90?±?6%) compared to ER (74?±?20%; p?d?=?0.87?±?0.40). Different sources of afferent information underpinned decision-making during SS. The extended durations of recovery during SS resulted in a reduced time ≥90% HR_max but enhanced time ≥105% MAS, compared with ER exercise. Differences in the afferent cue utilisation of participants likely explain the large levels of inter-individual variability observed.     

The modulation of corticospinal excitability and inhibition following acute resistance exercise in males and females

Objective: The acute responses to resistance training (RT) between males and females are poorly understood, especially from a neural perspective. Therefore, we aimed to compare the corticospinal and intracortical responses during fatigue and recovery following RT.

Methods: Twenty-two participants (12M, 10F) completed one-session of RT (3?×?12 repetition maximum) unilateral leg extensions with 60?s recovery. Single- and paired-pulse transcranial magnetic stimulation measured changes in the motor-evoked potential (MEP), corticospinal silent period (CSP), CSP/MEP ratio, and intracortical facilitation/inhibition (ICF, SICI). The maximal compound wave (M_MAX) measured peripheral excitability of the rectus femoris (RF) and maximal voluntary isometric contraction (MVIC) neuromuscular function of the leg extensors. Measures were taken immediately post, 30?min, 1 and 6?h post-training.

Results: A significantly greater increase in MEP/M_MAX ratio (p?=?.005) was observed for females immediately post-training compared to males. While no sex differences in MEP/M_MAX ratio was observed at 30?min and 1?h post-training, a greater MEP/M_MAX ratio for males was observed at 30?min (p?p?=?.003). CSP trended to decrease for males compared to females immediately post-training (d?=?1.93). MVIC was decreased post-training for males; 14.22% and females; 14.16% (P?MAX reduced at 30?min for both groups (P?P?>?.05).

Conclusion: The net output of corticospinal excitability is similar between males and females during fatigue. However, the mechanism in which this is modulated (increased MEP, decreased CSP) appears to be sex-specific.     

Influence of a caffeine mouth rinse on sprint cycling following glycogen depletion

Attenuated performance during intense exercise with limited endogenous carbohydrate (CHO) is well documented. Therefore, this study examined whether caffeine (CAF) mouth rinsing would augment performance during repeated sprint cycling in participants with reduced endogenous CHO. Eight recreationally active males (aged 23?±?2?yr, body mass 84?±?4?kg, stature 178?±?7?cm) participated in this randomized, single-blind, repeated-measures crossover investigation. Following familiarization, participants attended two separate evening glycogen depletion sessions. The following morning, participants completed five, 6?s sprints on a cycle ergometer (separated by 24?s active recovery), with mouth rinsing either (1) a placebo solution or (2) a 2% CAF solution. During a fifth visit, participants completed the sprints without prior glycogen depletion. Repeated-measures ANOVA identified significant main effect of condition (CAF, placebo, and control [P?P?P?P?P?P?相似文献   

Effects of strength,explosive and plyometric training on energy cost of running in ultra-endurance athletes

The aim of the present study was to evaluate the effects of a 12-week home-based strength, explosive and plyometric (SEP) training on the cost of running (Cr) in well-trained ultra-marathoners and to assess the main mechanical parameters affecting changes in Cr. Twenty-five male runners (38.2?±?7.1 years; body mass index: 23.0?±?1.1?kg·m^?2; V˙O₂max: 55.4?±?4.0 mlO₂·kg^?1·min^?1) were divided into an exercise (EG?=?13) and control group (CG?=?12). Before and after a 12-week SEP training, Cr, spring-mass model parameters at four speeds (8, 10, 12, 14?km·h^?1) were calculated and maximal muscle power (MMP) of the lower limbs was measured. In EG, Cr decreased significantly (p?<?.05) at all tested running speeds (?6.4?±?6.5% at 8?km·h^?1; ?3.5?±?5.3% at 10?km·h^?1; ?4.0?±?5.5% at 12?km·h^?1; ?3.2?±?4.5% at 14?km·h^?1), contact time (t_c) increased at 8, 10 and 12?km·h^?1 by mean +4.4?±?0.1% and t_a decreased by ?25.6?±?0.1% at 8?km·h^?1 (p?<?.05). Further, inverse relationships between changes in Cr and MMP at 10 (p?=?.013; r?=??0.67) and 12?km·h^?1 (p?<?.001; r?=??0.86) were shown. Conversely, no differences were detected in the CG in any of the studied parameters. Thus, 12-week SEP training programme lower the Cr in well-trained ultra-marathoners at submaximal speeds. Increased t_c and an inverse relationship between changes in Cr and changes in MMP could be in part explain the decreased Cr. Thus, adding at least three sessions per week of SEP exercises in the normal endurance-training programme may decrease the Cr.     

Physiological implications of preparing for a natural male bodybuilding competition

This study aimed to describe the body composition and physiological changes which take place during the in-season and recovery periods of a group of natural bodybuilders. Natural male bodybuilders (n?=?9) were assessed 16 (PRE16), 8 (PRE8), and 1 (PRE1) week(s) before, and 4 (POST4) weeks after a bodybuilding competition. Assessments included body composition, resting metabolic rate (RMR), serum hormones, and 7-day weighed food and training diaries. Change in parameters was assessed using repeated-measures analysis of variance. Dietary protein intake remained high throughout the study period (2.8–3.1?g?kg^?1?d^?1). Fat mass (FM) was significantly reduced from PRE16 to PRE1 (8.8?±?3.1 vs. 5.3?±?2.4?kg, P?.01). There was a small decrease in lean mass (LM) from PRE8 to PRE1 (71.8?±?9.1 vs. 70.9?±?9.1?kg, P?P?>?.05). Large reductions in total and free testosterone (16.4?±?4.4 vs. 10.1?±?3.6?nmol?L^?1, P?. 116.8?±?76.9?pmol?L^?1, P?. 19.9?±?7.6?nmol?L^?1, P?. 72.5?±?8.5?kg, P?. 25.4?±?9.3?nmol?L^?1, P?相似文献   

Validation of a single-stage submaximal treadmill walking test

Abstract

The single-stage treadmill walking test of Ebbeling et al. is commonly used to predict maximal oxygen consumption ([Vdot]O_2max) from a submaximal effort between 50% and 70% of the participant's age-predicted maximum heart rate. The purpose of this study was to determine if this submaximal test correctly predicts [Vdot]O_2max at the low (50% of maximum heart rate) and high (70% of maximum heart rate) ends of the specified heart rate range for males and females aged 18 – 55 years. Each of the 34 participants completed one low-intensity and one high-intensity trial. The two trials resulted in significantly different estimates of [Vdot]O_2max (low-intensity trial: mean 40.5 ml · kg^?1 · min^?1, s = 9.3; high-intensity trial: 47.5 ml · kg^?1 · min^?1, s = 8.8; P < 0.01). A subset of 22 participants concluded their second trial with a [Vdot]O_2max test (mean 47.9 ml · kg^?1 · min^?1, s = 8.9). The low-intensity trial underestimated (mean difference = ?3.5 ml · kg^?1 · min^?1; 95% CI = ?6.4 to ?0.6 ml · kg^?1 · min^?1; P = 0.02) and the high-intensity trial overestimated (mean difference = 3.5 ml · kg^?1 · min^?1; 95% CI = 1.1 to 6.0 ml · kg^?1 · min^?1; P = 0.01) the measured [Vdot]O_2max. The predictive validity of Ebbeling and colleagues' single-stage submaximal treadmill walking test is diminished when performed at the extremes of the specified heart rate range.     

Effects of competition on the sleep patterns of elite rugby union players

Abstract

No published research has assessed sleep patterns of elite rugby union players following match-play. The present study examined sleep patterns of professional rugby union players, prior and post-match-play, to assess the influence of competition. Twenty-eight male rugby union players (24.4?±?2.9 years, 103.9?±?12.2?kg) competed in one of four competitive home matches. Player's sleep behaviours were monitored continuously using an Actiwatch^® from two days before the match, until three days post-match. Repeated measures of analysis of variance (ANOVA) showed significant differences across the time points measured for time to bed (F?=?26.425, η² ?=?0.495, p < .001), get up time (F?=?21.175, η²?=?0.440, p?<?.001), time spent in bed (F?=?10.669, η²?=?0.283, p?<?.001), time asleep (F?=?8.752, η²?=?0.245, p?<?.001) and percentage of time moving (F?=?4.602, η²?=?0.146 p?<?.05). Most notable, post hocs revealed a significant increase for time in bed the night before the match (p?<?.01; 95% CI?=?0?:?10–1?:?28?h; 9.7?±?13.5%) compared with the reference night sleep. Furthermore, time asleep significantly decreased post-match (p?<?.05; 95% CI?=??0:03 to ?1:59?h; ?19.5?±?19.8%) compared to two nights pre-match. Across all time points, sleep latency and efficiency for most players were considered abnormal compared to that expected in normal populations. The results demonstrate that sleep that is deprived post-match may have detrimental effects on the recovery process.     

Exercise promotes IL-6 release from legs in older men with minor response to unilateral immobilization

Physical inactivity is a major contributor to low-grade systemic inflammation. Most of the studies characterizing interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α) release from exercising legs have been done in young, healthy men, but studies on inactivity in older people are lacking. The impact of 14 days of one-leg immobilization (IM) on IL-6 and TNF-α release during exercise in comparison to the contralateral control (CON) leg was investigated. Fifteen healthy men (age 68.1?±?1.1?year (mean?±?SEM); BMI 27.0?±?0.4 kg·m²; VO₂max 33.3?±?1.6 ml·kg^?1·min^?1) performed 45?min of two-leg dynamic knee extensor exercise at 19.5?±?0.9 W. Arterial and femoral venous blood samples from the CON and the IM legs were collected every 15?min during exercise, and thigh blood flow was measured with ultrasound Doppler. Arterial plasma IL-6 concentration increased with exercise (rest vs. 45?min, main effect p?p?p?=?.085, effect size 0.28) higher in the IM leg compared to the CON leg (288 (95% CI: 213–373) vs. 220 (95% CI: 152–299) pg·min^?1, respectively). There was no release of TNF-α in either leg and arterial concentrations remained unchanged during exercise (p?>?.05). In conclusion, exercise induces more pronounced IL-6 secretion in healthy older men. Two weeks of unilateral immobilization on the other hand had only a minor influence on IL-6 release. Neither immobilization nor exercise had an effect on TNF-α release across the working legs in older men.     

Sleep,training load and performance in elite female gymnasts

Training load (TL) and recovery should be in optimal balance to obtain maximal performance gains. We aimed to study sleep as a recovery technique and its relationship with TL and performance in elite athletes. Twenty-six elite female artistic gymnasts were divided into an under 13 (n?=?6), an under 14 (n?=?6), a junior (n?=?7; 14–15y) and a senior (=World Championship (WC) competitors, n?=?7; ≥16y) category. Sleep, through sleep logs, and training parameters, using the session Rate of Perceived Exertion (sRPE) scale, were monitored to calculate total sleep time (TST), sleep efficiency (SE), TL, monotony and strain. Performance of WC competitors was evaluated through coach and WC qualification ranking. For the entire group, TST (effect sizes (ES)?=??1.12, confidence intervals (CI)?=??60:?47, P?P?=?.022) were shorter during week than weekend nights. TST and SE were highest in youngest gymnasts (P?P?P?P?P?=?.030). TST correlated with coach ranking (r?=??0.857, P?=?.014). Higher TL correlated with worse WC (r?=?0.829, P?=?.042) and coach (r?=?0.893, P?=?.007) ranking. This research in elite gymnasts indicated associations between decreased TST, augmented TL and inferior performance. Optimizing sleep and TL may therefore represent strategies to enhance performance.     

The effects of work – rest duration on intermittent exercise and subsequent performance

This study examined the effects of different work?–?rest durations during 40?min intermittent treadmill exercise and subsequent running performance. Eight males (mean?±?s: age 24.3?±?2.0 years, body mass 79.4?±?7.0?kg, height 1.77?±?0.05?m) undertook intermittent exercise involving repeated sprints at 120% of the speed at which maximal oxygen uptake (v-[Vdot]O_2max) was attained with passive recovery between each one. The work?–?rest ratio was constant at 1:1.5 with trials involving short (6:9?s), medium (12:18?s) or long (24:36?s) work?–?rest durations. Each trial was followed by a performance run to volitional exhaustion at 150% v-[Vdot]O_2max. After 40?min, mean exercise intensity was greater during the long (68.4?±?9.3%) than the short work?–?rest trial (54.9?±?8.1% [Vdot]O_2max; P?<?0.05). Blood lactate concentration at 10?min was higher in the long and medium than in the short work?–?rest trial (6.1?±?0.8, 5.2?±?0.9, 4.5?±?1.3?mmol?·?l^?1, respectively; P?<?0.05). The respiratory exchange ratio was consistently higher during the long than during the medium and short work?–?rest trials (P <?0.05). Plasma glucose concentration was higher in the long and medium than in the short work?–?rest trial after 40?min of exercise (5.6?±?0.1, 6.6?±?0.2 and 5.3?±?0.5?mmol?·?l^?1, respectively; P?<?0.05). No differences were observed between trials for performance time (72.7?±?14.9, 63.2?±?13.2, 57.6?±?13.5?s for the short, medium and long work?–?rest trial, respectively; P = 0.17), although a relationship between performance time and 40?min plasma glucose was observed (P?<?0.05). The results show that 40?min of intermittent exercise involving long and medium work?–?rest durations elicits greater physiological strain and carbohydrate utilization than the same amount of intermittent exercise undertaken with a short work?–?rest duration.