Subsequent Athletic Performance Research Articles

A 7-min halftime jog mitigated the reduction in sprint performance for the initial 15-min of the second half in a simulated football match.

This study compared the effects of a 7-min shuttle jog during halftime to a control condition (seated rest) on subsequent athletic performance and lower-leg temperature in the second half. Eighteen male football players (22 years, 179 cm, 70 kg, 10 years of athletic career) randomly performed a 20-m shuttle jog (at an intensity of 70% of heart rate maximum) and a seated rest (sitting on a bench) during halftime in two separate sessions. A 5-min football simulation protocol consisting of football-specific activities (jumping, sprinting, kicking, passing, and dribbling at various intensities and distances) was repeated nine times to mimic the first and second half of a football match. Athletic performance (maximal vertical jump height, 20-m sprint time, and the Arrowhead agility test time) recorded during a 15-min period were averaged to represent each time point (first half: T1 to T3; second half: T4 to T6). Lower-leg skin and muscle (using the insulation disk technique) temperature was recorded before and after the first and second half. There was no condition effect over time in maximal vertical jump: F5,187 = 0.53, p = 0.75, Arrowhead agility test time: F5,187 = 1.25, p = 0.29, and lower-leg temperature (skin: F3,119 = 1.40, p = 0.25; muscle: F3,119 = 1.08, p = 0.36). The 20-m sprint time between conditions during the initial 15-min of the second half was different (condition × time: F5,187 = 2.42, p = 0.04) that subjects who performed the shuttle jog ran 0.09 sec faster (3.08 sec, p = 0.002, ES = 0.68), as compared with those who did the seated rest (3.17 sec). The results of our study confirmed that a decremental effect of the static rest on sprinting performance during the initial period of the second halftime can be attenuated by a halftime warm-up.

Does maternity during sports career jeopardize future athletic success in elite marathon runners?

The impact of maternity (Mat) on subsequent athletic performance is not well known. This study aims to investigate the impact of maternity among elite marathoners on their overall performance progression. For each runner listed in the top 150 female marathoners, who had experienced a mid-career maternity, performance development was reconstituted throughout the career. Maternity data and career break time span (Ttotal) were collected from publicly available informations. Performances were modelled according to the known age-performance relationship and the impact of maternity was added into the model. Linear mixed effect model was used to study the influence of maternity on the overall career. Among this sample, thirty-seven runners had at least 1 child during her career. Among them, fourteen had two children. Eleven runners (29.72%) made their personal best performance before Mat, which occurred at an average age of 28.40 ± 4.00 years. Twenty-six runners (70.28%) establish their best performances after Mat, at an average age of 32.20 ± 4.28. The age-performance relationship model explains 92% of the performance variability during the career’s progression. When age is considered, maternity does not have significant impact on performance development. World’s most competitive marathoners can still perform at their best level after pregnancy. The ability to return and surpass previous performance level is influenced by the age at which pregnancy occurs, relative to the age of peak performance during career development.

Prevalence and performance effects of neonatal disease in Thoroughbred and Standardbred foals in South-Eastern Australia.

There is little information on foal mortality and the epidemiology of diseases in the neonatal period in Australian equine breeding enterprises. This was a prospective cohort study of 1219 foals on 15 breeding farms in south-eastern Australia to identify the proportion of foals recognised on farm as abnormal at birth or within the first 48 h postpartum, determine the prevalence and risk factors for neonatal disease and assess the subsequent performance of foals in the study population. Overall, 27 foals died within 6 weeks of birth in the study population (2.2%), 142 foals (11.6%) were reported as abnormal at birth, and 304 (25.3%) were regarded as abnormal in the first 48 h postpartum. Non-septic orthopaedic disease (NSOD) was the most common abnormality recognised. Premature foals and foals born after dystocia or abnormal parturition were more likely to have clinical abnormalities recognised, but the intensity of nursing care did not predict outcome. Prophylactic administration of antimicrobial drugs was associated with increased mortality and septic disease. Maternal periparturient problems, foal gender, abnormality at birth and the presence of septic disease or neonatal maladjustment were associated with decreased performance outcomes, whereas measures to assess and augment passive immune transfer were associated with improved athletic performance. Information in the current study is important for the treatment and management decisions on farm and to identify industry welfare and production priorities. Although the incidence of all outcome variables was variable, factors recognised on farm in the peri-parturient period were predictive of subsequent athletic performance.

The effect of different post-exercise beverages with food on ad libitum fluid recovery, nutrient provision, and subsequent athletic performance

This study investigated the effect of consuming either water or a carbohydrate (CHO)-electrolyte sports beverage (‘Sports Drink’) ad libitum with food during a 4 h post-exercise recovery period on fluid restoration, nutrient provision and subsequent endurance cycling performance. On two occasions, 16 endurance-trained cyclists; 8 male [M] (age: 31 ± 9 y; VO2max: 54 ± 6 mL·kg−1·min−1) and 8 female [F] (age: 33 ± 8 y; VO2max: 50 ± 7 mL·kg−1·min−1); lost 2.3 ± 0.3% and 1.6 ± 0.3% of their body mass (BM), respectively during 1 h of fixed-intensity cycling. Participants then had ad libitum access to either Water or Sports Drink and food for the first 195 min of a 4 h recovery period. At the conclusion of the recovery period, participants completed a cycling performance test consisting of a 45 min fixed-intensity pre-load and an incremental test to volitional exhaustion (peak power output, PPO). Beverage intake; total water/nutrient intake; and indicators of fluid recovery (BM, urine output, plasma osmolality [POSM]) were assessed periodically throughout trials. Participants returned to a similar state of net positive fluid balance prior to recommencing exercise, regardless of the beverage provided (Water: +0.4 ± 0.5 L; Sports Drink: +0.3 ± 0.3 L, p = 0.529). While Sports Drink increased post-exercise energy (M: +1.8 ± 1.0 MJ; F: +1.3 ± 0.5 MJ) and CHO (M: +114 ± 31 g; F: +84 ± 25 g) intake (i.e. total from food and beverage) (p's < 0.001), this did not improve subsequent endurance cycling performance (Water: 337 ± 40 W [M] and 252 ± 50 W [F]; Sports Drink: 340 ± 40 W [M] and 258 ± 47 W [F], p = 0.242). Recovery beverage recommendations should consider the post-exercise environment (i.e. the availability of food), an individual's tolerance for food and fluid pre−/post-exercise, the immediate requirements for refuelling (i.e. CHO demands of the activity) and the athlete's overall dietary goals.

Effect of Varying Self-myofascial Release Duration on Subsequent Athletic Performance.

Phillips, J, Diggin, D, King, DL, and Sforzo, GA. Effect of varying self-myofascial release duration on subsequent athletic performance. J Strength Cond Res 35(3): 746-753, 2021-Self-myofascial release (SMR) treatments can enhance joint range-of-motion and restore movement function. The effects of different SMR durations on athletic performance have yet to be examined. Twenty-four volunteers had ankle and knee joint range-of-motion assessed using modified weight-bearing and kneeling lunge (KL) tests. Vertical jump and pro-agility sprint performance were also examined. All tests were conducted before and immediately after 1 (SMR_1) and 5 minutes (SMR_5) of foam rolling, and immediately after a control (CONTR) condition. Results showed KL scores increased after SMR_5 (16.4%; effect size [ES] = 0.85) when compared with SMR_1 (12.5%; ES = 0.58). Weight-bearing lunge scores showed little change after either SMR treatment. The CONTR condition exhibited little effect on joint range-of-motion. Vertical jump performance decreased after SMR_5 (5.1%; ES = 0.26) but changed little after SMR_1 (0.7%; ES = 0.03) and CONTR (1.9%; ES = 0.10) conditions. Pro-agility performance improved slightly after SMR_1 (1.1%) but deteriorated after CONTR (1.2%) and SMR_5 (0.5%). Effect size calculations for changes in pro-agility sprint times were trivial across all conditions (0.06-0.15). Data suggest that extended periods of SMR may be recommended, should improvements in joint range-of-motion be required. If power output is a critical requirement of subsequent exercise/performance tasks, prolonged SMR treatment (i.e., 5 minutes) should be avoided. Practitioners should be cautious when implementing SMR treatments within warm-ups.

The Importance of Post-Activation Potentiation (PAP) Training on Physical Fitness Preparation for Malaysian Female Hockey Players

A vast amount of research has been performed illustrating that the execution of certain conditioning activities at maximal or near-maximal intensities can acutely enhance subsequent athletic performance with given sufficient recovery. This phenomenon is known as post-activation potentiation (PAP) and its use within the field of strength and conditioning has grown rapidly as performance enhancing effects have been demonstrated within athletic movements such as jumping and sprinting. Objective: The purpose of this study is to analyse the effectiveness of PAP training on sprint performance and power production among Malaysian female hockey player. Methods: A total of 18 well-trained athletes (age 25 ± 3.7; mass 54 ± 4.9; height 160.8 ± 2.8; relative strength half-squat 1.9 ± 0.3; relative strength hex-bar deadlift 1.7 ± 0.5; relative strength hang clean 0.8 ± 0.1) were tested for 20 meter sprint time and counter-movement jump (CMJ) test during the preparation phase. This study used two different groups such as experimental group (EG) and control group (CG) and each player were randomly assigned. Both groups were completed training in twice per week for a period of eight week training program. The EG performed a total of 16 session by having 2 different training blocks. Each block has a period practice of training for 4 weeks and each block also has different types of exercise. Meanwhile, CG completed 16 session based on coach training program and did not practice at the same time with the EG. The study intervention program including pre-test and post-test activities were conducted before and after the study. Result: A data analysis of paired t-test and independent t-test was used and the level of significance in all statistical analyses was set at p ≤ 0.05. The result showed that 8-weeks of EG displayed significantly improved in sprint performance (p ≤ 0.005) and power production (p ≤ 0.005). Moreover, result also revealed a significant difference between EG and CG in sprint performance (p ≤ 0.000) and power production (p ≤ 0.008). Conclusion: In short, the result emphasized the contribution of kinetic and kinematic parameters for sprint and power performance. The EG result seem significant for athletic performance. Therefore, this findings is of great practical interest for coaches and fitness trainers and relevant to female hockey players and consequently maybe used in training program.

The Effect Of Varying Self-myofascial Release Duration On Subsequent Athletic Performance

Self-myofascial release (SMR) treatments appear to enhance joint range of motion (RoM) and restore movement function but the effects of different SMR durations on athletic performance have yet to be examined. PURPOSE: To investigate the effects of different SMR treatment durations (1 minute and 5 minutes) on joint RoM, power, and agility. METHODS: Twenty-four volunteers participated with ankle and knee joint RoM assessed using modified weight-bearing (WBL) and kneeling lunge (KL) tests. Vertical jump (VJ) performance and pro-agility (PA) sprint performance were also examined. All tests were conducted before and immediately after one-minute (SMR_1) and five-minutes (SMR_5) of SMR and immediately following a control (CONTR) condition. SMR was done on the quadriceps and triceps surae muscle groups using a standardized protocol and foam roller. Differences in dependent variables (VJ height, PA run time, WBL distance, KL angle) between treatment groups (SMR_1, SMR_5, CONTR) at two time-points (pre- and post-treatment) were analyzed using a 3 x 2-way repeated measures analysis of variance (ANOVA). Alpha = 0.05. Effect sizes (ES) were calculated to clarify the magnitude of the effect of differences between means from pre- to post-treatment for each treatment condition. RESULTS: KL angle increased following SMR_5 (16.4 %; ES = 0.85) when compared with SMR_1 (12.5 %; ES = 0.58). WBL distance showed little change following SMR treatments and the CONTR condition exhibited little effect on RoM tests. VJ height decreased following SMR_5 (5.1 %; ES = 0.26) but changed little following SMR_1 (0.7 %; ES = 0.03) and CONTR (1.9 %; ES = 0.10) conditions. PA run time improved slightly following SMR_1 (1.1 %) but deteriorated following CONTR (1.2 %) and SMR_5 (0.5 %). Effect size calculations for changes in PA, however, were trivial across all conditions (0.06 – 0.15). CONCLUSION: Extended periods of SMR may be recommended should improvements in joint RoM be required. If power output is a critical requirement of subsequent tasks, prolonged SMR treatment (i.e., 5-min) should be avoided.

Muscle cooling: too much of a good thing?

It is well documented that strenuous exercise elicits stress on the body, which may lead to physiological impairments and associated reductions in muscle function and fatigue, in the hours and days post-exercise. Whilst fatigue is specific to the mode, intensity and duration of exercise, a failure in any of the related neural, metabolic or mechanical processes may hinder subsequent athletic performance, particularly when insufficient restoration periods are provided. This has led to significant interest in recovery strategies to ameliorate post-exercise fatigue and to optimize an athlete’s physical capabilities.

Post-exercise Ingestion of Carbohydrate, Protein and Water: A Systematic Review and Meta-analysis for Effects on Subsequent Athletic Performance.

Athletes may complete consecutive exercise sessions with limited recovery time between bouts (e.g.≤4h). Nutritional strategies that optimise post-exercise recovery in these situations are therefore important. This two-part review investigated the effect of consuming carbohydrate (CHO) and protein with water (W) following exercise on subsequent athletic (endurance/anaerobic exercise) performance. Studies were identified by searching the online databases SPORTDiscus, PubMed, Web of Science and Scopus. Investigations that measured endurance performance (≥5min duration)≤4h after a standardised exercise bout (any type) under the following control vs. intervention conditions were included: Part 1: W vs. CHO ingested with an equal volume of W (CHO+W); and, Part 2: CHO+W vs. protein (PRO) ingested with CHO and an equal volume of W (PRO+CHO+W), where CHO or energy intake was matched. Publications were examined for bias using the Rosendal scale. Random-effects meta-analyses and meta-regression analyses were conducted to evaluate intervention efficacy. The quality assessment yielded a Rosendal score of 63±9% (mean±standard deviation). Part 1: 45 trials (n=486) were reviewed. Ingesting CHO+W (102±50g CHO; 0.8±0.6g CHOkg-1h-1) improved exercise performance compared with W (1.6±0.7L); %Δ mean power output=4.0, 95% confidence interval 3.2-4.7 (I 2=43.9). Improvement was attenuated when participants were 'Fed' (a meal 2-4h prior to the initial bout) as opposed to 'Fasted' (p=0.012). Part 2: 13 trials (n=125) were reviewed. Ingesting PRO+CHO+W (35±26g PRO; 0.5±0.4g PROkg-1) did not affect exercise performance compared with CHO+W (115±61g CHO; 0.6±0.3g CHO·kg bodymass-1h-1; 1.2±0.6L); %Δ mean power output=0.5, 95% confidence interval -0.5 to 1.6 (I 2=72.9). Athletes with limited time for recovery between consecutive exercise sessions should prioritise CHO and fluid ingestion to enhance subsequent athletic performance. PROSPEROREGISTRATION NUMBER: CRD42016046807.

Does Oral Fluid Intake Following Dehydration Influence Subsequent Athletic Performance? A Systematic Review and Meta-Analysis

Does Oral Fluid Intake Following Dehydration Influence Subsequent Athletic Performance? A Systematic Review and Meta-Analysis

Evening electronic device use: The effects on alertness, sleep and next-day physical performance in athletes

ABSTRACTThe aim of the present study was to investigate the influence of different types of tasks performed with or without an electronic device (tablet) on pre-sleep alertness, subsequent sleep quality and next-day athletic performance. Eight highly trained netball players attended a sleep laboratory for pre-sleep testing, polysomnographic sleep monitoring and next-day physical performance testing on 5 separate occasions (1 familiarisation and 4 experimental sessions). For 2 h prior to bedtime, athletes completed cognitively stimulating tasks (puzzles) or passive tasks (reading) with or without a tablet. Sleepiness tended to be greater after reading compared to completing puzzles without a tablet (d = 0.80), but not with a tablet. Melatonin concentration increased more so after reading compared to completing puzzles on a tablet (P = 0.02). There were no significant differences in sleep quality or quantity or next-day athletic performance between any of the conditions. These data suggest that using a tablet for 2 h prior to sleep does not negatively affect subsequent sleep or next-day performance in athletes.

Acute effects of muscle stretching on physical performance, range of motion, and injury incidence in healthy active individuals: a systematic review.

Recently, there has been a shift from static stretching (SS) or proprioceptive neuromuscular facilitation (PNF) stretching within a warm-up to a greater emphasis on dynamic stretching (DS). The objective of this review was to compare the effects of SS, DS, and PNF on performance, range of motion (ROM), and injury prevention. The data indicated that SS- (-3.7%), DS- (+1.3%), and PNF- (-4.4%) induced performance changes were small to moderate with testing performed immediately after stretching, possibly because of reduced muscle activation after SS and PNF. A dose-response relationship illustrated greater performance deficits with ≥60 s (-4.6%) than with <60 s (-1.1%) SS per muscle group. Conversely, SS demonstrated a moderate (2.2%) performance benefit at longer muscle lengths. Testing was performed on average 3-5 min after stretching, and most studies did not include poststretching dynamic activities; when these activities were included, no clear performance effect was observed. DS produced small-to-moderate performance improvements when completed within minutes of physical activity. SS and PNF stretching had no clear effect on all-cause or overuse injuries; no data are available for DS. All forms of training induced ROM improvements, typically lasting <30 min. Changes may result from acute reductions in muscle and tendon stiffness or from neural adaptations causing an improved stretch tolerance. Considering the small-to-moderate changes immediately after stretching and the study limitations, stretching within a warm-up that includes additional poststretching dynamic activity is recommended for reducing muscle injuries and increasing joint ROM with inconsequential effects on subsequent athletic performance.

Recovery Effects of Hyperoxic Gas Inhalation Or Contrast Water Immersion on the Postexercise Cytokine Response, Perceptual Recovery, and Next Day Exercise Performance

The effect of different recovery modalities on the postexercise cytokine response, perceptual recovery, and subsequent day athletic performance were investigated. Eight highly trained athletes completed 3 swimming sessions consisting of 20 × 200 m efforts, in a counterbalanced repeated-measures design. At the conclusion of each session, athletes undertook a 30-minute recovery intervention of contrast water therapy (CWT), supplemental oxygen (HYP), or passive rest (CON). Venous blood samples were analyzed for levels of interleukin-6 (IL-6) at the pre-, post-, and 30-minute postswim time points, and a rating of perceived recovery was recorded at the conclusion of the 30-minute intervention and upon returning to the pool 12 hour later. Finally, a 200-m swim time trial was completed as a measure of next day performance. The results showed that there was a significant increase in IL-6 at the completion of exercise, which persisted after 30 minutes of recovery (p < 0.05), with no differences evident between the groups. Additionally, the perception of recovery after the 30-minute intervention was significantly lower in the CON when compared with the CWI and HYP (p < 0.05). However, there were no differences in the 12-hour postrecovery time trial performances. These results suggest that a 30-minute recovery intervention using CWT or HYP has limited influence on the acute-phase response or on improving subsequent day athletic performance. However, strength and conditioning specialists should encourage the use of a structured postexercise recovery procedure because the evidence suggests that the acute perception of recovery is much greater when some form of intervention is implemented in comparison with no recovery procedure at all.

Ten Minutes of Dynamic Stretching Is Sufficient to Potentiate Vertical Jump Performance Characteristics

The current literature recommends dynamic rather than static stretching for the athletic warm-up. Dynamic stretching and various conditioning stimuli are used to induce potentiation in subsequent athletic performance. However, it is unknown as to which type of activity in conjunction with dynamic stretching within a warm-up provides the optimal potentiation of vertical jump performance. It was the objective of the study to examine the possible potentiating effect of various types of conditioning stimuli with dynamic stretching. Twenty athletes participated in 6 protocols. All the experimental protocols included 10 minutes of dynamic stretching. After the dynamic stretching, the subjects performed a (a) concentric (DS/CON): 3 sets of 3 repetition maximum deadlift exercise; (b) isometric (DS/ISOM): 3 sets of 3-second maximum voluntary contraction back squats; (c) plyometric (DS/PLYO): 3 sets of 3 tuck jumps; (d) eccentric (DS/ECC): 3 modified drop jumps; (e) dynamic stretching only (DS), and (f) control protocol (CON). Before the intervention and at recovery periods of 15 seconds, 4, 8, 12, 16, and 20 minutes, the participants performed 1-2 maximal countermovement jumps. The DS and DS/CON protocols generally had a 95-99% likelihood of exceeding the smallest worthwhile change for vertical jump height, peak power, velocity and force. However, the addition of the deadlift to the DS did not augment the potentiating effect. Time-to-peak potentiation was variable between individuals but was most consistent between 3 and 5 minutes. Thus, the volume and the intensity associated with 10 minutes of dynamic stretching were sufficient to provide the potentiation of vertical jump characteristics. Additional conditioning activities may promote fatigue processes, which do not permit further potentiation.

A Fresh Look at the Process of Arriving at a Clinical Prognosis. Part 3: Neonatal Illness

Determining the prognosis in a sick newborn foal is complicated by the following three factors: the normal transition from maternal/placental dependence to independence, intrauterine conditions before birth, and the birth process itself. In addition, there are several vulnerabilities and unique characteristics of the neonatal foal that are not shared by older foals or adult horses. However, the same principles of assessing homeostasis apply to establishing a prognosis in a sick neonate, as previously described for the adult. Overall, survival rates for septic critically ill foals generally vary between 60% and 80%. In noncritical yet seriously ill foals—a diverse group sometimes referred to as the “sick, nonseptic foal”—survival rates typically range from 75% to 95% with proper medical care. Long-term survival rates are lower for all categories of sick foals, and subsequent athletic performance may be adversely affected by sepsis or septic arthritis/osteomyelitis.

Hematological changes and athletic performance in horses in response to high altitude (3,800 m)

This study had two goals: 1) measure hematologic changes with high-altitude acclimatization in horses; and 2) assess the effect of 9 days at high altitude on subsequent athletic performance at low altitude. Six horses performed standardized exercise tests on a dirt track (before and during time at altitude) and treadmill (pre- and postaltitude exposure). Resting and immediate postexercise blood samples were measured for blood volume, lactate, red cell number, packed cell volume, and 2,3-diphosphoglycerate (DPG) concentrations at 225 m, over a 9-day period at 3,800 m, and shortly after returning to 225 m. Acclimatization produced increases in total red cell volume (38.2 +/- 2.4 to 48.1 +/- 2.9 ml/kg, P = 0.004) and DPG/hemoglobin concentrations (19.4 +/- 1.7 increased to 29.4 +/- 0. 4 micromol/g, P = 0.004). Two performance variables, heart rate recovery postexercise and lactate recovery, were faster after acclimatization.

Precompetitive mood states and performance of elite male golfers: do trait characteristics make a difference?

The relationship between preperformance mood, measured by the Profile of Mood States inventory, and subsequent athletic performance has been the focus of considerable research. Presumably, athletes with less positive mood profiles should be outperformed by those with more favorable profiles. The results presented so far in the literature are equivocal. One possible explanation is that more stable trait characteristics might medicate mood states prior to competitive situations. In the present study, 8 male golf players, all members of the Swedish National Team, completed a number of trait inventories (Eysenck's Personality Inventory, Locus of Control, Sport Competition Anxiety Test, Self-consciousness Scale) prior to the competitive season. Subsequently, they completed the Profile of Mood States before each game played. Analysis showed that the players' preperformance mood states differed significantly and that these differences were associated with their scores on the trait inventories. Furthermore, preperformance mood states were significantly related to athletic performance for some individuals but not for others. Further research should also include trait measurements to understand better the relationship between mood states and the athletic performance of individual athletes.

Life after Winning Gold: II. Coping with Change as an Olympic Gold Medallist

The experiences of 18 Olympic gold medallists from Australia are analyzed relative to the changes effected by their Olympic wins. Specifically, the effect an Olympic win has on subsequent athletic performance is addressed as are athletes’ strategies for coping with changes faced after winning a gold medal and recommendations for future Olympic champions. Athletes perceived that both preparation and focus for subsequent competitions were affected by an Olympic win and saw most of these changes as negative influences. Athletes’ coping strategies were similar to those reported by other elite athletes. Recommendations for helping prepare elite athletes for the changes associated with high-level athletic success are discussed.

Influence d'une privation partielle de sommeil sur l'adaptation à l'exercice physique

Les effets d'une privation de trois heures de sommeil en milieu de nuit sur l'adaptation de l'organisme à un exercice physique ont été étudiés chez huit athlètes endurants de niveau régional. Les nuits de sommeil précédant l'effort ont été contrôlées en laboratoire. L'épreuve d'effort s'est déroulée sur bicyclette ergométrique. Sa chronologie a consisté en quatre étapes: échauffement de 10 minutes, effort sous-maximal à puissance fixe (75% de la consommation maximale d'oxygène) pendant 20 minutes, augmentation progressive de la charge de travail jusqu'à épuisement du sujet et, enfin, récupération de 15 minutes. À effort sous-maximal stable et à effort maximal supporté, les valeurs de fréquence cardiaque, de ventilation, d'équivalent respiratoire pour l'oxygène et de lactatémie sont plus élevées lorsque l'exercice est conduit après privation partielle de sommeil que celles obtenues lors de l'exercice effectué après une nuit témoin. À effort maximal, la consommation d'oxygène est abaissée alors que la puissance supportée de travail est identique. This study was aimed at investigating the effects of a partial sleep deprivation on the subsequent athletic performance. Eight highly trained cyclists were enrolled for this study. The changes in cardio-vascular, ventilatory and metabolic responses were analysed during and upon completion of physical exercise, taking place after 2 recorded nights, in other words, after a control night and after a night with reduced sleep. Partial sleep deprivation was obtained by waking the subjects for 3 h in the middle of the night. Athletic performance was tested at 2 pm the following day, using an ergometer. The subjects were pedaling at a steady-state submaximal work load (75% of the maximal oxygen uptake) and then at the maximal sustained work load. The analyses of change scores disclosed that there were main significant effects for measures of heart rate, ventilation, oxygen uptake, V̇E/V̇O 2 ratio and lactate levels under the observed conditions. Mean exercise duration and maximal sustained work load after partial sleep deprivation were not modified with control. On the other hand, heart rate was significantly greater during sub-maximal, maximal performances, and during recovery after sleep loss. Sleep deprivation significantly increased ventilation at exercise intensities eliciting 75% and 100% of the maximal oxygen uptake (V̇O 2 max) and during the recovery, since it significantly decreased V̇O 2 during maximal work. The V̇E/V̇O 2 ratio was greater at the end of the steady state and at the end of the maximal work load. Lactate levels were altered by sleep loss, undergoing upward drift from the 9th min of the steady state until recovery. These findings suggest that acute sleep loss may contribute to alterations in atlhetic performance.

Delayed menarche in swimmers in relation to age at onset of training and athletic performance

Competitive swimmers have been considered to be different from other female athletes in that their mean age at menarche is similar to that of nonathletes. However, it was hypothesized that if the delayed menarche observed in athletes of other sports is caused by prepubertal training, then swimmers should also exhibit delayed menarche as the majority of swimmers begin training prior to puberty. Furthermore, if early prepubertal training is the important factor in delaying menarche, then it was hypothesized that a relationship between performance and age at menarche in swimming is unlikely to exist. Thus, 345 competitive female swimmers and 549 control subjects completed questionnaires concerning general health, athletic training history, and age at menarche. Results indicated that, as a population, the mean age at menarche of the swimmers (13.4 yr) was significantly later than the controls (13.0 yr). When swimmers and controls were compared on an age-group basis, it was found that the difference in age at menarche was due to the data obtained from the older and more highly competitive swimmers. Assigning swimmers to different competitive levels or by performance in specific swimming events (50- or 100-yd freestyle; 45.7- or 91.4-m, respectively) indicated a significantly later age at menarche for the more competitive swimmers. Thus, there is evidence that the age at menarche and subsequent athletic performance in swimming are related; the later menarche observed in swimmers appears to be associated with factors that select for superior performance.