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1.
ABSTRACT

The purpose of this study was to expand our previously published sweat normative data/analysis (n = 506) to establish sport-specific normative data for whole-body sweating rate (WBSR), sweat [Na+], and rate of sweat Na+ loss (RSSL). Data from 1303 athletes were compiled from observational testing (2000–2017) using a standardized absorbent sweat patch technique to determine local sweat [Na+] and normalized to whole-body sweat [Na+]. WBSR was determined from change in exercise body mass, corrected for food/fluid intake and urine/stool loss. RSSL was the product of sweat [Na+] and WBSR. There were significant differences between sports for WBSR, with highest losses in American football (1.51 ± 0.70 L/h), then endurance (1.28 ± 0.57 L/h), followed by basketball (0.95 ± 0.42 L/h), soccer (0.94 ± 0.38 L/h) and baseball (0.83 ± 0.34 L/h). For RSSL, American football (55.9 ± 36.8 mmol/h) and endurance (51.7 ± 27.8 mmol/h) were greater than soccer (34.6 ± 19.2 mmol/h), basketball (34.5 ± 21.2 mmol/h), and baseball (27.2 ± 14.7 mmol/h). After ANCOVA, significant between-sport differences in adjusted means for WBSR and RSSL remained. In summary, due to the significant sport-specific variation in WBSR and RSSL, American football and endurance have the greatest need for deliberate hydration strategies.

Abbreviations: WBSR: whole body sweating rate; SR: sweating rate; Na+: sodium; RSSL: rate of sweat sodium loss  相似文献   

2.
Observational research on professional athletes from the USA suggests differences may exist in sweat sodium loss based on ethnic differences. The New Zealand (NZ) sporting population is mainly of European or Māori/Pacific Island origin. Therefore, this study aimed to describe the fluid-electrolyte balance of athletes by ethnicity. A total of 20 Māori/Pacific Islanders (MP; body mass 100.97 ± 13.05 kg) and 29 NZ European (NZE; body mass 89.11 ± 11.56 kg) elite male athletes were recruited. Sweat rates were determined by body mass change during a 1-h spin cycle exercise session, during which fluid intakes and heart rate were recorded. Sweat samples were analysed for sodium concentration. Mean ± SD sweat sodium concentrations were 73.4 ± 27.2 mmol·L?1 and 55.5 ± 26.8 mmol·L?1 for the MP and NZE groups, respectively (p = 0.070). Sweat rate was 0.93 ± 0.26 L·h?1 for the MP group and 0.89 ± 0.33 L·h?1 for the NZE group (p = 0.357). Fluid intake was 1.05 ± 0.48 L and 0.93 ± 0.49 L for MP and NZE, respectively (p = 0.395). Half of the MP group gained weight during the exercise session compared to 37% of the NZE group. Pre-exercise urine specific gravity was significantly lower amongst the NZE group (1.016 ± 0.009 g mL?1) than the MP group (1.024 ± 0.008 g mL?1) p = 0.001. There was no significant difference in heart rate between the groups, p = 0.082. Hydration practices of athletes in NZ may differ by ethnicity, and this may highlight the need for more targeted education by ethnicity.  相似文献   

3.
Abstract

This study examined the relationship between intensity of training and changes in hydration status, core temperature, sweat rate and composition and fluid balance in professional football players training in the heat. Thirteen professional football players completed three training sessions; “higher-intensity” (140 min; HI140), “lower-intensity” (120 min; LI120) and “game-simulation” (100 min; GS100). Movement demands were measured by Global Positioning System, sweat rate and concentration were determined from dermal patches and body mass change. Despite similar environmental conditions (26.9 ± 0.1°C and 65.0 ± 7.0% relative humidity [Rh]), higher relative speeds (m · min?1) and increased perceptions of effort and thermal strain were observed in HI140 and GS100 compared with LI120 (P < 0.05). Significantly (P < 0.05) greater sweat rate (L · h?1) and electrolyte losses (g) were observed in HI140 and GS100 compared with LI120. Rate of rise in core temperature was correlated with mean speed (r = 0.85), session rating of perceived exertion (sRPE) (r = 0.61), loss of potassium (K+) (r = 0.51) sweat rate (r = 0.49), and total sweat loss (r = 0.53), with mean speed the strongest predictor. Sodium (Na+) (r = 0.39) and K+ (r = 0.50) losses were associated with total distance covered. In hot conditions, individualised rehydration practices should be adopted following football training to account for differences in sweat rate and electrolyte losses in response to intensity and overall activity within a session.  相似文献   

4.
There is a paucity of studies that have evaluated substrate utilisation and protein catabolism during multiday strenuous exercise in athletes. Eleven well-trained male cyclists completed 3 h of race-simulated cycling on 4 consecutive days. Cyclist exercised 2 h postprandially and with carbohydrate supplementation (~50 g · h?1) during exercise. Whole body substrate utilisation was measured by indirect calorimetry, protein catabolism from sweat and urine urea excretion, and blood metabolite concentration was evaluated. Protein catabolism during exercise was significantly greater on days 2–4 (29.9 ± 8.8; 34.0 ± 11.2; 32.0 ± 7.3 g for days 2, 3, and 4, respectively) compared to day 1 (23.3 ± 7.6 g), P < 0.05. Fat oxidation was greater at 21 km (~45 min) on days 2–4 (1.06 ± 0.23; 1.08 ± 0.25; 1.12 ± 0.29 g · min?1) compared to day 1 (0.74 ± 0.23 g · min?1, P < 0.05), but the rate of carbohydrate and fat oxidation was similar between days at 50 and 80 km. Whole body substrate utilisation is altered on subsequent days of multiday prolonged strenuous cycling that includes a quicker transition to greater fat utilisation from exercise onset and a 28–46% greater reliance on endogenous protein catabolism on all successive days.  相似文献   

5.
Abstract

In 219 recreational male runners, we investigated changes in body mass, total body water, haematocrit, plasma sodium concentration ([Na+]), and urine specific gravity as well as fluid intake during a 100-km ultra-marathon. The athletes lost 1.9 kg (s = 1.4) of body mass, equal to 2.5% (s = 1.8) of body mass (P < 0.001), 0.7 kg (s = 1.0) of predicted skeletal muscle mass (P < 0.001), 0.2 kg (s = 1.3) of predicted fat mass (P < 0.05), and 0.9 L (s = 1.6) of predicted total body water (P < 0.001). Haematocrit decreased (P < 0.001), urine specific gravity (P < 0.001), plasma volume (P < 0.05), and plasma [Na+] (P < 0.05) all increased. Change in body mass was related to running speed (r = ?0.16, P < 0.05), change in plasma volume was associated with change in plasma [Na+] (r = ?0.28, P < 0.0001), and change in body mass was related to both change in plasma [Na+] (r = ?0.36) and change in plasma volume (r = 0.31) (P < 0.0001). The athletes consumed 0.65 L (s = 0.27) fluid per hour. Fluid intake was related to both running speed (r = 0.42, P < 0.0001) and change in body mass (r = 0.23, P = 0.0006), but not post-race plasma [Na+] or change in plasma [Na+] (P > 0.05). In conclusion, faster runners lost more body mass, runners lost more body mass when they drank less fluid, and faster runners drank more fluid than slower runners.  相似文献   

6.
Abstract

The aim of this study was to determine the match activity and physiological demands of women's tennis during a 3-day clay-court tennis tournament. The activity profile of eight players was determined by filming each competitive match with video cameras. Metabolic-perceptual measurements–blood samples and individual ratings of perceived exertion (RPE)–were taken while the players were sitting during permitted changeover breaks in play. The activity profile of the players was as follows: strokes per rally, 2.5 ± 1.6; rally duration, 7.2 ± 5.2 s; rest time between rallies, 15.5 ± 7.3 s; effective playing time, 21.6 ± 6.1%; work-to-rest ratio, 1:2.1. Blood lactate concentration [2.2 ± 0.9 mmol · l?1 (n = 50) vs. 2.2 ± 0.7 mmol · l?1 (n = 48)] and RPE values [12.2 ± 2.4 (n = 57) vs. 12 ± 2.3 (n = 57)] were not significantly different (P = 0.65–0.78) between service and return games. The results highlight the importance of taking these factors (i.e. activity patterns and physiological profile) into account when planning training strategies for competitive females players. As such, tennis training regimes should be adapted to the specific demands imposed by match-play in female players on a clay-court surface.  相似文献   

7.
Abstract

The current study implemented a two-part design to (1) assess the vitamin D concentration of a large cohort of non-vitamin D supplemented UK-based athletes and 30 age-matched healthy non-athletes and (2) to examine the effects of 5000 IU · day?1 vitamin D3 supplementation for 8-weeks on musculoskeletal performance in a placebo controlled trial. Vitamin D concentration was determined as severely deficient if serum 25(OH)D < 12.5 nmol · l?1, deficient 12.5–30 nmol · l?1 and inadequate 30–50 nmol · l?1. We demonstrate that 62% of the athletes (38/61) and 73% of the controls (22/30) exhibited serum total 25(OH)D < 50 nmol · l?1. Additionally, vitamin D supplementation increased serum total 25(OH)D from baseline (mean ± SD = 29 ± 25 to 103 ± 25 nmol · l?1, P = 0.0028), whereas the placebo showed no significant change (53 ± 29 to 74 ± 24 nmol · l?1, P = 0.12). There was a significant increase in 10 m sprint times (P = 0.008) and vertical-jump (P = 0.008) in the vitamin D group whereas the placebo showed no change (P = 0.587 and P = 0.204 respectively). The current data supports previous findings that athletes living at Northerly latitudes (UK = 53° N) exhibit inadequate vitamin D concentrations (<50 nmol · l?1). Additionally the data suggests that inadequate vitamin D concentration is detrimental to musculoskeletal performance in athletes. Future studies using larger athletic groups are now warranted.  相似文献   

8.
Purpose: Correlations between fatigue-induced changes in exercise performance and maximal rate of heart rate (HR) increase (rHRI) may be affected by exercise intensity during assessment. This study evaluated the sensitivity of rHRI for tracking performance when assessed at varying exercise intensities. Method: Performance (time to complete a 5-km treadmill time-trial [5TTT]) and rHRI were assessed in 15 male runners following 1 week of light training, 2 weeks of heavy training (HT), and a 10-day taper (T). Maximal rate of HR increase (measured in bpm·s?1) was the first derivative maximum of a sigmoidal curve fit to HR data recorded during 5 min of running at 8 km·h?1 (rHRI8km·h?1), and during subsequent transition to 13 km·h?1 (rHRI8–13km·h?1) for a further 5 min. Results: Time to complete a 5-km treadmill time-trial was likely slower following HT (effect size ± 90% confidence interval = 0.16 ± 0.06), and almost certainly faster following T (–0.34 ± 0.08). Maximal rate of HR increase during 5 min of running at 8 km·h?1 and rHRI8–13km·h?1 were unchanged following HT and likely increased following T (0.77 ± 0.45 and 0.66 ± 0.62, respectively). A moderate within-individual correlation was found between 5TTT and rHRI8km·h?1 (r value ± 90% confidence interval = –.35 ± .32). However, in a subgroup of athletes (n = 7) who were almost certainly slower to complete the 5TTT (4.22 ± 0.88), larger correlations were found between the 5TTT and rHRI8km·h?1 (r = –.84 ± .22) and rHRI8–13km·h?1 (r = –.52 ± .41). Steady-state HR during rHRI assessment in this group was very likely greater than in the faster subgroup (≥ 1.34 ± 0.86). Conclusion(s): The 5TTT performance was tracked by both rHRI8km·h?1 and rHRI8–13km·h?1. Correlations between rHRI and performance were stronger in a subgroup of athletes who exhibited a slower 5TTT. Individualized workloads during rHRI assessment may be required to account for varying levels of physical conditioning.  相似文献   

9.
Abstract

Aspects of team players' performance are negatively affected when ~ 2% body mass is lost by perspiration. Although such dehydration is likely reached during summer practice in outdoors sports, it is unclear if such dehydration is achieved during the practice of indoor sports. We assessed the fluid and electrolyte deficits of elite team players during practice for the following indoor sports: indoor soccer (n=9), basketball (n=11), volleyball (n=10), and handball (n=13). Morning hydration status was estimated by measuring urine specific gravity. Sweat rate was calculated from body mass changes and fluid intake. Sweat sodium concentration from the forearm was used to estimate whole-body sodium losses. Over 91% of the players were moderately hypohydrated (urine specific gravity>1.020) at waking 3 h before practice. Indoor soccer players sweated at a higher rate (1.8 litres · h?1) than volleyball and handball players (1.2 and 1.1 litres · h?1, respectively; P<0.05), whereas sweat rate was not different between basketball players (1.5 litres · h?1) and the other team sport players (P>0.05). In average, 62±13% of sweat losses were replaced and teams' body mass loss did not exceed 1.2±0.3%. Sodium losses were similar among teams, averaging 1.2±0.2 g. The exercise fluid replacement habits of professional indoor team players are adequate to prevent 2% dehydration. However, most players could benefit from increasing fluid intake between workouts to offset the high prevalence of morning hypohydration.  相似文献   

10.
Abstract

This study was designed to investigate the effect of ingesting a glucose plus fructose solution on the metabolic responses to soccer-specific exercise in the heat and the impact on subsequent exercise capacity. Eleven male soccer players performed a 90 min soccer-specific protocol on three occasions. Either 3 ml · kg?1 body mass of a solution containing glucose (1 g · min?1 glucose) (GLU), or glucose (0.66 g · min?1) plus fructose (0.33 g · min?1) (MIX) or placebo (PLA) was consumed every 15 minutes. Respiratory measures were undertaken at 15-min intervals, blood samples were drawn at rest, half-time and on completion of the protocol, and muscle glycogen concentration was assessed pre- and post-exercise. Following the soccer-specific protocol the Cunningham and Faulkner test was performed. No significant differences in post-exercise muscle glycogen concentration (PLA, 62.99 ± 8.39 mmol · kg wet weight?1; GLU 68.62 ± 2.70; mmol · kg wet weight?1 and MIX 76.63 ± 6.92 mmol · kg wet weight?1) or exercise capacity (PLA, 73.62 ± 8.61 s; GLU, 77.11 ± 7.17 s; MIX, 83.04 ± 9.65 s) were observed between treatments (P > 0.05). However, total carbohydrate oxidation was significantly increased during MIX compared with PLA (P < 0.05). These results suggest that when ingested in moderate amounts, the type of carbohydrate does not influence metabolism during soccer-specific intermittent exercise or affect performance capacity after exercise in the heat.  相似文献   

11.
This study aimed to validate the use of a single blood lactate concentration measure taken following a 12 km h?1 running stage (BLC12) to predict and monitor fixed blood lactate concentration (FBLC) thresholds. Three complementary studies were undertaken. Study I: the relationships between BLC12 and the running speeds at FBLC of 3 mmol L?1 (S3mM) and 4 mmol L?1 (S4mM) measured during a multistage running field test were examined in 136 elite athletes. Study II: data from 30 athletes tested one year apart were used to test the predictive capacity of the equations obtained in Study I. Study III: 80 athletes were tested before and after an intensified training period to examine whether training-induced changes in FBLC thresholds could be predicted and monitored by BLC12. Study I: BLC12 was significantly (P < 0.001) and inversely related to S3mM (R2 = 0.89) and S4mM (R2 = 0.95). Study II: prediction models yielded robust correlations between the estimated and measured FBLC thresholds (r = 0.94–0.99; P < 0.001). Study III: estimated changes predicted actual training-induced changes in FBLC thresholds (r = 0.81–0.91; P < 0.001). This study gives empirical support to use a single lactate measure during a sub-maximal running field test as a simple, low-cost and practical alternative to FBLC thresholds in athletes.  相似文献   

12.
Abstract

The aim of this study was to assess over time the hydration status of taekwon-do athletes during a preparatory camp. Measures of urine osmolality, conductivity, specific gravity and colour were made on the first urine sample passed by the participants (n = 32) in the morning before breakfast. The urinary measurements were made on samples collected at the beginning of the camp, 5 days later and one day before competition. Body mass was also measured at the same instants. Body mass (mean ± s) was essentially the same on each of the measurement days (62.6 ± 12.2, 62.7 ± 12.3 and 62.2 ± 12.6 kg, respectively). Mean urine osmolality at the beginning of the camp was relatively high (998 ± 171 mOsmol · kg?1), suggesting that a significant number of the athletes were already hypohydrated. However, no significant differences were detected in urine osmolality at the three time points during the study. There were no significant differences in any of the four methods of urine analysis during the study (P > 0.05). The average values for all samples were 989 ± 205 mOsmol · kg?1 for osmolality, 25.5 ± 6.7 mS · cm?1 for conductivity, 1.017 ± 0.010 g · cm?3 for specific gravity and 4 ± 1 arbitrary units for colour. Correlation analysis between the different methods suggested moderately good agreement (correlation coefficient = 0.5–0.7) between all four measurement techniques (P < 0.01). The coefficients of variation for these techniques were relatively low (CV = 11.8 – 35.0%). The results of this study suggest that some of the taekwon-do athletes were slightly hypohydrated in the morning on each of the test days, but there was no evidence to suggest that most of the athletes further restricted their fluid intake to make weight. In addition, it appears that each of the four methods used gave essentially the same estimate of hydration status of these athletes.  相似文献   

13.
Background: To determine athletes perceived and measured indices of fluid balance during training and the influence of hydration strategy use on these parameters. Methods: Thirty-three professional rugby union players completed a 120 minute training session in hot conditions (35°C, 40% relative humidity). Pre-training hydration status, sweat loss, fluid intake and changes in body mass (BM) were obtained. The use of hydration assessment techniques and players perceptions of fluid intake and sweat loss were obtained via a questionnaire. Results: The majority of players (78%) used urine colour to determine pre-training hydration status but the use of hydration assessment techniques did not influence pre-training hydration status (1.025?±?0.005 vs. 1.023?±?0.013?g.ml?1, P?=?.811). Players underestimated sweat loss (73?±?17%) to a greater extent than fluid intake (37?±?28%) which resulted in players perceiving they were in positive fluid balance (0.5?±?0.8% BM) rather than the measured negative fluid balance (?1.0?±?0.7% BM). Forty-eight percent of players used hydration monitoring strategies during exercise but no player used changes in BM to help guide fluid replacement. Conclusion: Players have difficulty perceiving fluid intake and sweat loss during training. However, the use of hydration monitoring techniques did not affect fluid balance before or during training.  相似文献   

14.
Abstract

In this study, we assessed exercise intensity in 20 water polo games of different duration. The hypothesis that right wing players perform at a higher intensity than back and forward central players was also tested. Thirty water polo players, equally split between three field positions, participated in the study. Initially, their performance-related physiological capabilities were evaluated. Subsequently, during water polo games of short (4×7-min periods) or long duration (4×9-min periods), heart rate was monitored continuously and blood lactate concentration was measured at the end of each period. Activity patterns were also recorded using a video camera. Mean heart rate over the entire game was 156 ± 18 beats · min?1. Overall exercise intensity fluctuated around a value corresponding to the lactate threshold (4.03 ± 0.96 mmol · l?1, 86 ± 5% of peak heart rate) and decreased (P < 0.003) with game time (4.22 ± 1.8 and 3.47 ± 1.9 mmol · l?1 in the second and fourth quarter, respectively). During the last 6 min, heart rate was higher (P < 0.001) in games of short duration (156 ± 3 beats · min?1) than in games of long duration (152 ± 8 beats · min?1). Video analysis showed that the percentage of time spent in low-intensity activities (i.e. “out of game”) was lower (23 vs. 26%), whereas that in high-intensity activities (i.e. “sprinting crawl”) was higher (21 vs. 19%), in games of short compared with long duration. No difference was observed among players of various field positions in any of the variables examined. Thus during match-play, games of long duration produced significantly lower heart rate responses than games of short duration, and the physiological response exhibited by the players was not affected by field position. The water polo authorities should consider these results before changing game duration and coaches should prepare their athletes accordingly.  相似文献   

15.
There are few data in the published literature on sweat loss and drinking behaviour in athletes training in a cool environment. Sweat loss and fluid intake were measured in 17 first-team members of an elite soccer team training for 90 min in a cool (5°C, 81% relative humidity) environment. Sweat loss was assessed from the change in body mass after correction for the volume of fluid consumed. Sweat electrolyte content was measured from absorbent patches applied at four skin sites. Mean (?± s) sweat loss during training was 1.69?±?0.45 l (range 1.06?-?2.65 l). Mean fluid intake during training was 423?±?215 ml (44?-?951 ml). There was no apparent relationship between the amount of sweat lost and the volume of fluid consumed during training (r 2 = 0.013, P = 0.665). Mean sweat sodium concentration was 42.5?±?13.0 mmol?·?l?1 and mean sweat potassium concentration was 4.2?±?1.0 mmol?·?l?1. Total salt (NaCl) loss during training was 4.3?±?1.8 g. The sweat loss data are similar to those recorded in elite players undergoing a similar training session in warm environments, but the volume of fluid ingested is less.  相似文献   

16.
Abstract

Determination of the strongest possible relationship between isokinetic quadriceps and functional performance measurements in healthy females would allow sports medicine practitioners to establish normative values when examining muscular performance in injured females. Previous attempts to correlate both measurements have, however, produced inconsistent results. The purpose of this study was to examine the effects of allometric scaling, isokinetic testing velocities, reciprocal and non-reciprocal isokinetic testing on the relationship between countermovement jump (CMJ) and isokinetic quadriceps torque and power in recreational females athletes. Seventeen females (age 21.0 ± 2.0 years, body mass index 19.5 ± 1.0 kg · m?2) performed isokinetic quadriceps and CMJ tests. Isokinetic peak torque and average power were obtained reciprocally and non-reciprocally at 1.05 and 3.14 rad · s?1, and were corrected for body mass by allometric modelling. Pearson product–moment correlation (r) was used to assess the relationship between the isokinetic parameters and the CMJ measurements. Coefficients of determination (r 2) were calculated to determine the magnitude of common variance. The r-values for all non-allometrically modelled non-reciprocal parameters were greater (r = 0.58–0.63) than isokinetic parameters obtained reciprocally (r = 0.28–0.47). Using allometric scaling, non-reciprocal isokinetic data accounted for an additional 2–9% of the CMJ height variance, and statistically significant correlations were obtained at both 1.05 and 3.14 rad · s?1. Allometrically scaled, non-reciprocal isokinetic peak torque and average power at 1.05 rad · s?1 had the highest correlation with CMJ (r 2 = 0.49). At both 1.05 and 3.14 rad · s?1, non-reciprocal quadriceps parameters correlated more closely with CMJ measurements than do reciprocal contractions. Normalization for body size by allometrically scaling may further improve correlations with CMJ performance.  相似文献   

17.
Abstract

The purpose of this study was to compare changes in aerobic condition, strength, and muscular endurance following 8 weeks of endurance rowing alone or in combination with weight-training. Twenty-two elite rowers were assigned to (1) rowing (n = 10, 250–270 km · week?1) or (2) rowing (n = 12, 190–210 km · week?1) plus four weight-training sessions each week. Pre and post mean and standardized effect-size (ES) differences in aerobic condition (watts at 4 mmol · L?1) and strength (isometric pull, N), prone bench-pull (6-repetition maximum, 6-RM), 5- and 30-repetition leg-press and 60-repetition seated-arm-pull (J, performed on a dynamometer) normalized by body mass and log-transformed were analysed, after adjusting for gender. The standardized differences between groups were trivial for aerobic condition (ES [±90% CI] = 0.15; ±0.28, P = 0.37) and prone bench-pull (ES = 0.27; ±0.33, P = 0.18), although a moderate positive benefit in favour of rowing only was observed for the seated-arm-pull (ES = 0.42; ±0.4, P = 0.08). Only the weight-training group improved isometric pull (12.4 ± 8.9%, P < 0.01), 5-repetition (4.0 ± 5.7%, P < 0.01) and 30-repetition (2.4 ± 5.4%, P < 0.01) leg-press. In conclusion, while gains in aerobic condition and upper-body strength were comparable to extensive endurance rowing, weight-training led to moderately greater lower-body muscular-endurance and strength gains.  相似文献   

18.
Abstract

The effect of active and passive recovery on repeated-sprint swimming bouts was studied in eight elite swimmers. Participants performed three trials of two sets of front crawl swims with 5 min rest between sets. Set A consisted of four 30-s bouts of high-intensity tethered swimming separated by 30 s passive rest, whereas Set B consisted of four 50-yard maximal-sprint swimming repetitions at intervals of 2 min. Recovery was active only between sets (AP trial), between sets and repetitions of Set B (AA trial) or passive throughout (PP trial). Performance during and metabolic responses after Set A were similar between trials. Blood lactate concentration after Set B was higher and blood pH was lower in the PP (18.29 ± 1.31 mmol · l?1 and 7.12 ± 0.11 respectively) and AP (17.56 ± 1.22 mmol · l?1 and 7.14 ± 0.11 respectively) trials compared with the AA (14.13 ± 1.56 mmol · l?1 and 7.23 ± 0.10 respectively) trial (P < 0.01). Performance time during Set B was not different between trials (P > 0.05), but the decline in performance during Set B of the AP trial was less marked than in the AA or PP trials (main effect of sprints, P < 0.05). Results suggest that active recovery (60% of the 100-m pace) could be beneficial between training sets, and may compromise swimming performance between repetitions when recovery durations are short (< 2 min).  相似文献   

19.
This study examined the separate and combined effects of heat acclimation and hand cooling on post-exercise cooling rates following bouts of exercise in the heat. Seventeen non-heat acclimated (NHA) males (mean ± SE; age, 23 ± 1 y; mass, 75.30 ± 2.27 kg; maximal oxygen consumption [VO2 max], 54.1 ± 1.3 ml·kg?1·min?1) completed 2 heat stress tests (HST) when NHA, then 10 days of heat acclimation, then 2 HST once heat acclimated (HA) in an environmental chamber (40°C; 40%RH). HSTs were 2 60-min bouts of treadmill exercise (45% VO2 max; 2% grade) each followed by 10 min of hand cooling (C) or no cooling (NC). Heat acclimation sessions were 90–240 min of treadmill or stationary bike exercise (60–80% VO2 max). Repeated measures ANOVA with Fishers LSD post hoc (α < 0.05) identified differences. When NHA, C (0.020 ± 0.003°C·min?1) had a greater cooling rate than NC (0.013 ± 0.003°C·min?1) (mean difference [95%CI]; 0.007°C [0.001,0.013], P = 0.035). Once HA, C (0.021 ± 0.002°C·min?1) was similar to NC (0.025 ± 0.002°C·min?1) (0.004°C [?0.003,0.011], P = 0.216). Hand cooling when HA (0.021 ± 0.002°C·min?1) was similar to when NHA (0.020 ± 0.003°C·min?1) (P = 0.77). In conclusion, when NHA, C provided greater cooling rates than NC. Once HA, C and NC provided similar cooling rates.  相似文献   

20.
Abstract

Squash is a popular racket sport that requires intermittent activity with frequent bursts of near maximal-intensity exercise. Consequently, effective physiological and thermoregulatory responses are important contributors to performance during squash match-play. Controlled field-based simulation protocols have been introduced in a growing number of sports, which allow sports scientists to investigate changes in physiology and the efficacy of various interventions in sport-specific contexts. This study aimed to develop an exercise protocol that simulates the physiological requirements of elite squash match-play. Eight elite junior squash players (age 16.2 ± 0.8 years, height 1.76 ± 0.06 m, body mass 61.3 ± 5.9 kg; mean ± s) completed the following in a randomized order: (1) a squash match against a player of similar standard and (2) a squash-specific incremental exercise protocol (multistage squash test [MST]) followed by the squash simulation protocol (SSP). The multistage squash test was continued for 18.0 ± 1.0 min and elicited near maximal post-MST heart rates, blood lactate concentrations and ratings of perceived exertion (198 ± 9 beats · min?1, 5.7 ± 1.7 mmol · l?1 and 18 ± 1, respectively). The SSP was 12.2 min in length compared with mean game length during competitive matches of 10.0 ± 1.6 min (P = 0.27). Peak heart rates were similar during the SSP and match-play (192 ± 11 and 189 ± 6 beats · min?1, respectively; P = 0.44). Mean exercising heart rates were similar during the SSP (180 ± 8 beats · min?1) and match-play (179 ± 13 beats · min?1; P = 0.73). Peak blood lactate concentrations during the SSP and match-play were 3.5 ± 1.5 and 2.4 ± 1.2 mmol · l?1 (P = 0.07), respectively. Peak ratings of perceived exertion during the SSP and match-play were similar (17 ± 2 and 17 ± 2, respectively; P = 0.64). It was concluded that the SSP closely replicated the demands of squash match-play in elite junior squash players. Furthermore, the SSP provides coaches and scientific support staff with a controlled squash-specific exercise protocol that has potential application in the objective investigation of a range of interventions such as training programmes, nutritional supplements and strategies to maintain core body temperature.  相似文献   

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