首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Weight-making practices have been shown to impair musculoskeletal and physiological function of jockeys. This study investigated the “in-race” heart rate (HR) responses and hydration status during competitive racing, as well as selected physiological and lifestyle parameters of professional jockeys based in Hong Kong. “In-race” HR responses and early morning hydration status of 20 male jockeys were examined in hot and moderate climactic occasions. Additionally, bone mineral density (BMD), dietary intake and lifestyle choices were assessed. Osteopenia was observed in the calcanei of jockeys (left: 0.51 ± 0.06; right: 0.46 ± 0.12 g · cm?2). Energy and protein intake were significantly lower on a race day compared to a non-race day (P < 0.05). “In-race” HRmax values were similar to those from VO2max laboratory tests (186 ± 14 vs. 185 ± 8 bpm). Hypohydration was observed on both racing days. (USG: 1.0247 ± 0.006 and 1.0256 ± 0.0258 mg · L?1 for hot and moderate conditions, respectively). Sauna usage (25.5%) and food restriction (20.4%) were the most common weight-making practices. Current lifestyle choices of jockeys result in suboptimal bone health, hydration status and nutritional intake, which can significantly enhance the fracture risk. Further research should develop exercise and nutrition guidelines for optimising their skeletal health.  相似文献   

2.
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   

3.
Abstract

In this study we investigated pre-training hydration status, fluid intake, and sweat loss in 20 elite male Brazilian adolescent soccer players (mean ± s: age 17.2 ± 0.5 years; height 1.76 ± 0.05 m; body mass 69.9 ± 6.0 kg) on three consecutive days of typical training during the qualifying phase of the national soccer league. Urine specific gravity (USG) and body mass changes were evaluated before and after training sessions to estimate hydration status. Players began the days of training mildly hypohydrated (USG > 1.020) and fluid intake did not match fluid losses. It was warmer on Day 1 (33.1 ± 2.4°C and43.4 ± 3.2% relative humidity; P < 0.05) and total estimated sweat losses (2822 ± 530 mL) and fluid intake (1607 ± 460 mL) were significantly higher (P < 0.001) compared with Days 2 and 3. Data also indicate a significant correlation between the extent of sweat loss and the volume of fluid consumed (Day 1: r = 0.560, P = 0.010; Day 2: r = 0.445, P = 0.049; Day 3: r = 0.743, P = 0.0001). We conclude that young, native tropical soccer players arrive hypohydrated to training and that they exhibit voluntary dehydration; therefore, enhancing athletes' self-knowledge of sweat loss during training might help them to consume sufficient fluid to match the sweat losses.  相似文献   

4.
Dietary intake, vitamin status and oxidative stress were evaluated in 17 elite male boxers. Ten of them frequently reduced body weight rapidly before competitions (Weight Loss Group) and 7 did not practice rapid weight loss (Control Group). Food record checklists, blood samples for determination of vitamin status and plasma glutathione levels were obtained during a week of weight maintenance, a pre-competition week and a post-competition week. The average dietary intakes in both groups were 33 ± 8 kcal·kg?1, 3.7 ± 1.1 g·kg?1 carbohydrates, 1.5 ± 0.4 g·kg?1 protein, 1.2 ± 0.4 g·kg?1 fat and 2.2 ± 1.0 L water per day (excluding pre-competition week in Weight Loss Group). Energy (18 ± 7 kcal·kg?1), carbohydrate (2.2 ± 0.8 g·kg?1), protein (0.8 ± 0.4 g·kg?1), fat (0.6 ± 0.3 g·kg?1) and water (1.6 ± 0.6 L) consumption (P-values <0.001) and intakes of most vitamins (P-values < 0.05) were significantly reduced during the pre-competition week in the Weight Loss Group. In both groups, the intakes of vitamins A, E and folate were below recommended values throughout the three periods; however, blood vitamin and plasma glutathione levels did not change significantly. Our findings indicate a low-caloric and low-carbohydrate diet in elite boxers, regardless of participating in rapid weight loss or not. Apparently, the pre-competitional malnutitrition in the Weight Loss Group did not induce alterations in the vitamin and glutathione status.  相似文献   

5.
This investigation (i) examined changes in tear osmolarity in response to fluid loss that occurs with exercise in a field setting, and (ii) compared tear osmolarity with common field and laboratory hydration measures. Sixty-three participants [age 27.8 ± 8.4 years, body mass 72.15 ± 10.61 kg] completed a self-paced 10 km run outside on a predetermined course. Body mass, tear fluid, venous blood and urine samples were collected immediately before and after exercise. Significant (p < 0.001) reductions in body mass (1.71 ± 0.44%) and increases in tear osmolarity (8 ± 15 mOsm.L?1), plasma osmolality (7 ± 8 mOsm.kg?1), and urine specific gravity (0.0014 ± 0.0042 g.mL?1; p = 0.008) were observed following exercise. Pre- to post-exercise change in tear osmolarity was not significantly correlated (all p > 0.05) with plasma osmolality (rs = 0.24), urine osmolality (rs = 0.14), urine specific gravity (rs = 0.13) or relative body mass loss (r = 0.20). Tear osmolarity is responsive to exercise-induced fluid loss but does not correlate with the changes observed using other common measures of hydration status in the field setting. Practitioners shouldn’t directly compare or replace other common hydration measures with tear osmolarity in the field.

Abbreviations: BML: Body Mass Loss; CV: Coefficient of Variation; Posm: Plasma osmolality; SD: Standard Deviation; Tosm: Tear Osmolarity; Uosm: Urine Osmolality; USG: Urine Specific Gravity; WBGT: Wet bulb globe thermometer  相似文献   

6.
Laboratory-based studies indicate mild dehydration adversely affects mood. Although ultra-endurance events often result in mild to moderate dehydration, little research has evaluated whether the relationship between hydration status and mood state also exists in these arduous events. Therefore, the purpose of this study was to evaluate how hydration status affected mood state and perceptual measures during a 161 km ultra-endurance cycling event. One hundred and nineteen cyclists (103 males, 16 females; age = 46 ± 9 years; height = 175.4 ± 17.9 cm; mass = 82.8 ± 16.3 kg) from the 2011 and 2013 Hotter’N Hell events participated. Perceived exertion, Thermal, Thirst, and Pain sensations, Brunel Profile of Mood States, and urine specific gravity (USG) were measured pre- (~1 h before), mid- (~97 km), and post-ride. Participants were classified at each time point as dehydrated (USG ≥ 1.022) or euhydrated (USG ≤ 1.018). Independent of time point, dehydrated participants (USG = 1.027 ± 0.004) had decreased Vigour and increased Fatigue, Pain, Thirst, and Thermal sensations compared to euhydrated participants (USG = 1.012 ± 0.004; all P < 0.01). USG significantly correlated with Fatigue (r = 0.36), Vigour (r = ?0.27), Thirst (r = 0.15), and Pain (r = 0.22; all P < 0.05). In conclusion, dehydrated participants had greater Fatigue and Pain than euhydrated participants. These findings indicate dehydration may adversely affect mood state and perceptual ratings during ultra-endurance cycling.  相似文献   

7.
Abstract

Excess protein intake can adversely affect the bone via an increase in calcium excretion, while suitable mechanical loading promotes osteogenesis. We therefore investigated whether vibration exposure could alleviate the bone mineral losses associated with a metabolic acidosis. Ten healthy individuals aged 22 – 29 years (median = 25) underwent three 5-day study periods while monitoring their dietary intake. The study consisted of recording the participants' usual dietary intake for 5 consecutive days. Participants were then randomly divided into two groups, one of which received a protein supplement (2 g · kg?1 body mass · day?1; n = 5) and the other whole-body low-magnitude (3.5 g), low-frequency (30 Hz) mechanical vibration (WBV) delivered through a specially designed vibrating plate for 10 min each day (n = 5). Finally, for the third treatment period, all participants consumed the protein supplement added to their normal diet and were exposed to WBV exercise for 10 min per day. Daily urine samples were collected throughout the experimental periods to determine the excretion of calcium, phosphate, titratable acid, urea, and C-telopeptide. As expected, when the participants underwent the high protein intake, there was an increase in urinary excretion rates of calcium (P < 0.001), phosphate (P < 0.003), urea (P < 0.001), titratable acid (P < 0.001), and C-telopeptide (P < 0.05) compared with baseline values. However, high protein intake coupled with vibration stimulation resulted in a significant reduction in urinary calcium (P = 0.006), phosphate excretion (P = 0.021), and C-telopeptide (P < 0.05) compared with protein intake alone, but did not affect titratable acid and urea output. The participants showed no effect of WBV exercise alone on urinary excretion of calcium, phosphate, urea, titratable acid, or C-telopeptide. The results indicate that vibration stimulation can moderate the increase in bone resorption and reduction in bone formation caused by a metabolic acidosis.  相似文献   

8.
Abstract

Low energy availability [(energy intake – exercise expenditure)/kg lean body mass], a component of the Female Athlete Triad, has been associated with menstrual disturbances and low bone mass. No studies have examined the energy availability of athletes across a season. The purpose of this study was to assess the prevalence of, and what contributes to, low energy availability in Division I female soccer players across a season. Nineteen participants aged 18–21 years (mean [Vdot]O2max: 57.0 ± 1.0 mL · kg?1 · min?1) were studied during the pre, mid, and post season. Mean energy availability was overall lowest at mid season, and lower at mid than post season (35.2 ± 3.7 vs. 44.5 ± 3.7 kcal · kg?1 lean body mass, P = 0.009). Low energy availability (<30 kcal · kg?1 lean body mass) was observed in 5/19 (26.3%), 5/15 (33.3%), and 2/17 (11.8%) of participants during the pre, mid, and post season. Dietary energy intake was lower mid (P = 0.008) and post season (P = 0.022) than it was pre season (pre: 2794 ± 233 kcal · day?1; mid: 2208 ± 156 kcal · day?1; post: 2161 ± 143 kcal · day?1). Exercise energy expenditure decreased significantly (P ≤ 0.001) over time (pre: 819 ± 57 kcal · day?1; mid: 642 ± 26 kcal · day?1; post: 159 ± 28 kcal · day?1). Low energy availability was due to lower dietary energy intake at lunch during pre season (P = 0.014) and during lunch and dinner during mid season (P ≤ 0.030). Energy availability was inversely related to body dissatisfaction (r = ?0.62, P = 0.017) and drive for thinness (r = ?0.55, P = 0.041) during mid season. Although most Division I female soccer players are not at risk for low energy availability, a concerning proportion exhibited low energy availability at pre or mid season. Further studies are needed to explore strategies to prevent and monitor low energy availability in these athletes.  相似文献   

9.
Purpose: The purpose of this study was to quantify and compare training and competition demands in basketball. Methods: Fifteen semiprofessional male basketball players wore microsensors during physical conditioning training (PCT), games-based training (GBT), and competition to measure absolute and relative (·min?1) PlayerLoadTM (PL) and estimated equivalent distance (EED). Internal responses were calculated using absolute and relative session rating of perceived exertion (sRPE) and summated heart rate zones (SHRZ). Integrated measures were calculated as sRPE:PL and SHRZ:PL ratios. Results: PlayerLoad (arbitrary units [AU]) and EED (m) were statistically significantly (p < .05) higher during PCT (632 ± 139 AU, d = 1.36; 5,964 ± 1,312 m, d = 1.36; 6.50 ± 0.81 AU·min?1, d = 2.44; 61.88 ± 7.22 m·min?1, d = 2.60) and GBT (624 ± 113 AU, d = 1.54; 5,892 ± 1,080 m, d = 1.53; 6.10 ± 0.77 AU·min?1, d = 2.14; 56.76 ± 6.49 m·min?1, d = 2.22) than they were during competition (449 ± 118 AU; 3,722 ± 1474 m; 4.35 ± 1.09 AU·min?1; 41.01 ± 10.29 m·min?1). Summated heart rate zones were statistically significantly (p < .05) higher during PCT (314 ± 86 AU, d = 1.05; 3.22 ± 0.50 AU·min?1, d = 1.94) and GBT (334 ± 79 AU, d = 1.38; 3.19 ± 0.54 AU·min?1, d = 1.83) than they were during competition (225 ± 77 AU; 2.17 ± 0.69 AU·min?1). The ratio of sRPE:PL was statistically significantly (p < .05) higher during competition (1.58 ± 0.85) than during PCT (0.98 ± 0.22, d = 1.44) and GBT (0.91 ± 0.24, d = 1.90). Conclusion: Training demands exceeded competition demands.  相似文献   

10.
Adequate dietary strategies are essential for the successful participation in ultra-endurance races. The aim of this study was to evaluate and compare the energy and water intakes of participants during three different mountain ultra-endurance runs. The study took place at the “Ultra Mallorca Serra de Tramuntana” (Mallorca, Spain), an ultra-endurance mountain event with runners participating either in a 44-km (Marathon, n = 51), a 67-km (Trail, n = 109) or a 112-km (Ultra, n = 53) run competition. Participants in the study answered a questionnaire focused on the nutritional intake within an hour after finishing the competition. Mean energy intake during the competitions was 183 kcal · h¯1, with an average carbohydrate intake of 31 g · h¯1 (52.1% of participants consumed less than 30 g · h¯1). No significant differences between competitions were found in these parameters. However, a higher percentage of energy from lipids in participants in the Trail and the Ultra was found (P = 0.034). Furthermore, significant differences were observed in water intake per hour of competition (P = 0.039), with the lowest value for the intake during the Ultra competition. In conclusion, the majority of the participants in the study present low carbohydrate intakes. However, fluid intake seems to be adequate. Different distances did not significantly influence the participants’ nutritional strategies.  相似文献   

11.
Abstract

The aim of the present study was to examine the relationship between intensities of exercise during match-play of elite-standard soccer referees with those of the players from the same match. Match analysis data were collected (Prozone® Leeds, UK) for 18 elite-standard soccer referees (age 26–49 years) on FA Premier League matches during the 2008/09 English FA Premier League season (236 observations). Running categories for referees and players were as follows: total distance covered (m); high-speed running distance (speed >19.8 km · h?1); and sprinting distance (speed >25.2 km · h?1). Analysis of the distance–time regression coefficients revealed no differences between the referees' and players' within-match rates of change for total distance covered (?0.594 ± 0.394 vs. ?0.713 ± 0.269 m · min?1; P = 0.104), high-speed running (?0.039 ± 0.077 vs. ?0.059 ± 0.030 m · min?1; P = 0.199), and sprinting (?0.003 ± 0.039 vs. ?0.021 ± 0.017 m · min?1; P = 0.114). In addition, there were no differences between across-season rates of change for total distance (–26.756 ± 40.434 vs. ?20.031 ± 25.502 m per match day; P = 0.439) and sprinting (–9.662 ± 7.564 vs. ?8.589 ± 4.351 m per match day; P = 0.542). These results show that elite-standard soccer referees' intensities of exercise during match-play are interrelated with those of the players and thus demonstrate that referees are able to keep pace with the players during FA Premier League matches.  相似文献   

12.
Abstract

The purpose of this study was to examine macronutrient intake, energy density and energy intake distribution that may be associated with low energy availability (EA) in Division I female soccer players. The energy intake, exercise energy expenditure and EA of 19 participants (18–21 years) was assessed during the pre-, mid- and postseasons. Repeated measures analysis of variance was performed to examine the changes across the season. Chi-square analysis was performed to examine the distribution of participants meeting the American College of Sports Medicine recommendations for carbohydrate and protein consumption. Independent t-tests were used to compare differences between groups. The proportion of athletes who did not meet the American College of Sports Medicine recommendations for carbohydrate intake (6–10 g . kg–1 BW) was significantly greater in the low (<30 kcal . kg–1 LBM) than higher (≥30 kcal . kg–1 LBM) EA group (χ2 (1) = 7.5; P = 0.006). Participants with low compared to higher EA consumed a lower energy dense dinner (0.8 ± 0.1 vs. 1.4 ± 0.1 kcal . g–1; P = 0.004) after a soccer match during midseason. No differences in the percentage (%) of kilocalories from food (84.5 ± 2.0% vs. 84.7 ± 2.6%), sports drinks (7.3 ± 1.4% vs. 6.0 ± 3.2%), other drinks (7.6 ± 1.5 % vs. 6.0 ± 1.5%) or bars/gels/beans (1.7 ± 0.6 vs. 3.0 ± 1.5) were observed in participants with low compared to higher EA (P > 0.05) during the pre- and midseasons. Identifying inadequate carbohydrate intake and the practice of consuming lower energy dense meals may be important in preventing low EA conditions and consequently the Female Athlete Triad.  相似文献   

13.
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   

14.
ABSTRACT

The aims of this study were to analyse the optimal cadence for peak power production and time to peak power in bicycle motocross (BMX) riders. Six male elite BMX riders volunteered for the study. Each rider completed 3 maximal sprints at a cadence of 80, 100, 120 and 140 revs · min?1 on a laboratory Schoberer Rad Messtechnik (SRM) cycle ergometer in isokinetic mode. The riders’ mean values for peak power and time of power production in all 3 tests were recorded. The BMX riders produced peak power (1105 ± 139 W) at 100 revs · min?1 with lower peak power produced at 80 revs · min?1 (1060 ± 69 W, (F(2,15) = 3.162; P = .266; η2 = 0.960), 120 revs · min?1 (1077 ± 141 W, (F(2,15) = 4.348; P = .203; η2 = 0.970) and 140 revs · min?1 (1046 ± 175 W, (F(2,15) = 12.350; P = 0.077; η2 = 0.989). The shortest time to power production was attained at 120 revs · min?1 in 2.5 ± 1.07 s. Whilst a cadence of 80 revs · min?1 (3.5 ± 0.8 s, (F(2,15) = 2.667; P = .284; η2 = 0.800) 100 revs · min?1 (3.00 ± 1.13 s, (F(2,15) = 24.832; P = .039; η2 = 0.974) and 140 revs · min?1 (3.50 ± 0.88 s, (F(2,15) = 44.167; P = .006; η2 = 0.967)) all recorded a longer time to peak power production. The results indicate that the optimal cadence for producing peak power output and reducing the time to peak power output are attained at comparatively low cadences for sprint cycling events. These findings could potentially inform strength and conditioning training to maximise dynamic force production and enable coaches to select optimal gear ratios.  相似文献   

15.
The purpose of this study was to investigate the relationship between running economy (RE) and performance in a homogenous group of competitive Kenyan distance runners. Maximal aerobic capacity (VO2max) (68.8 ± 3.8 ml?kg?1?min?1) was determined on a motorised treadmill in 32 Kenyan (25.3 ± 5.0 years; IAAF performance score: 993 ± 77 p) distance runners. Leg anthropometry was assessed and moment arm of the Achilles tendon determined. While Achilles moment arm was associated with better RE (r2 = 0.30, P = 0.003) and upper leg length, total leg length and total leg length to body height ratio were correlated with running performance (r = 0.42, P = 0.025; r = 0.40, P = 0.030 and r = 0.38, P = 0.043, respectively), RE and maximal time on treadmill (tmax) were not associated with running performance (r = ?0.01, P = 0.965; r = 0.27; P = 0.189, respectively) in competitive Kenyan distance runners. The dissociation between RE and running performance in this homogenous group of runners would suggest that RE can be compensated by other factors to maintain high performance levels and is in line with the idea that RE is only one of many factors explaining elite running performance.  相似文献   

16.
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   

17.
Abstract

In this study, video and force analysis techniques were used to distinguish between dragon boat paddlers of different ability. Six elite paddlers (three males, three females) and six sub-elite paddlers (two males, four females) were compared during high-intensity paddling (80–90 strokes · min?1). Video filming was conducted for two-dimensional kinematic analysis and an instrumented paddle was used to collect force data. Paddling efficiency, paddle force characteristics, and paddler kinematic variables were measured. Elite paddlers achieved higher paddling efficiency than sub-elite paddlers (elite: 76 ± 4%; sub-elite: 67 ± 10%; P = 0.080). Elite paddlers also showed higher peak force (elite: 16.3 ± 4.8 N · kg?2/3; sub-elite: 11.4 ± 2.6 N · kg?2/3; P = 0.052), average force (elite: 7.9 ± 2.8 N · kg?2/3; sub-elite: 5.5 ± 1.4 N · kg?2/3; P = 0.084), and impulse (elite: 3.0 ± 0.9 (N · s) · kg?2/3; sub-elite: 1.9 ± 0.4 (N · s) · kg?2/3; P = 0.026) than sub-elite paddlers, but these three results should be viewed with caution due to the small sample size and the unequal number of males and females in the two groups. Superior technique and greater strength enable the elite paddlers to achieve higher paddling efficiency. Paddlers use different joint movement patterns to develop propulsion, which are reflected in variations in the force–time curve.  相似文献   

18.
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   

19.
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   

20.
Abstract

The aim of this study was to include self-paced exercise within a modified Loughborough Intermittent Shuttle Test (LIST-P) in order to quantify key performance variables not possible with prescribed workloads. Sixteen male games players performed two trials of the LIST-P, at least 7 days apart. The LIST-P incorporates 4 × 15-min blocks of “prescribed-pace” activity (participants exercise in time to audible signals) followed by 2 × 15-min blocks of “self-paced” running (no audible signals). Distances covered and mean speeds were monitored during self-paced exercise. Total distance covered (12.54 ± 0.45 km vs. 12.64 ± 0.32 km; P = 0.10) and mean speed (8.37 ± 0.31 km ? h?1 vs. 8.44 ± 0.22 km ? h?1; P = 0.10) was similar between trials. Other indices also showed the test to be reliable (Pearson’s correlation = 0.89 and 0.90 (P < 0.01), total distance and mean speed, respectively; intraclass correlation coefficient = 0.88 and 0.88 (P < 0.01); standard error of measurement = ±0.13 km and ±0.09 km ? h?1; coefficient of variation (CV) = 1.7% and 1.7%; ratio limits of agreement = 1.00 */÷1.03 and 1.01 */÷1.04). Sprint time was also similar between trials (2.60 ± 0.19 s vs. 2.64 ± 0.23 s; P = 0.29). Incorporating self-paced exercise within an established intermittent shuttle running test appears to be a sensitive means of quantifying key performance variables for multiple-sprint sports research.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号