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1.
Physical education (PE) teachers have a physically demanding job, putting them at a considerable risk for musculoskeletal injuries. To structurally develop tailored injury prevention programmes for PE teachers, a clear understanding of the extent, characteristics and underlying factors of their musculoskeletal injuries compared to referents is necessary. Therefore, the current study prospectively followed 103 PE teachers and 58 non-PE teachers, who registered musculoskeletal injuries and time of exposure to sports participation during one school year. Pearson χ2-tests and independent samples t-tests determined significant differences between PE and non-PE teachers regarding demographics and variables possibly related to injury occurrence. PE teachers had 1.23 and non-PE teachers 0.78 injuries/teacher/school year. This difference was significantly different after adjustment for hours spent weekly on intracurricular teaching during the career and for injury history during the preceding six months (P = 0.009; OR = 0.511; 95% CI = 0.308–0.846). PE teachers’ most affected body parts were the knee and the back. PE teachers had a more extensive injury history (P < 0.001), a higher work- (P < 0.001) and sport index (P < 0.001), practiced more sports (P < 0.002) and taught more extracurricular sports (P = 0.001). Future injury prevention programmes should take account for the great injury history and heavy physical load in PE teachers.  相似文献   

2.
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   

3.
Controversial results reported in past research pertaining to the effectiveness of sport-based physical activity interventions on weight loss. The purpose of this study was to assess the impact of sport-based physical activity intervention on body weight in children and adolescents using a meta-analysis. Academic Search Complete, Education Source, ERIC, Medline, ProQuest, PsycINFO and SportDiscus databases were searched from January 2000 to April 2015. Eighteen studies met following inclusion criteria: sport-based intervention studies; subjects aged 6–18 years; reported body weight; published in peer-reviewed journals written in English. The mean intervention duration was 17.72 weeks. The overall effect size (ES) was 0.52 (Cohen’s d (ES) = 0.52, 95% CI = 0.08, 0.95, P = 0.021), using a random effects model. Moderator analyses results showed that the Q statistic for the sport type (individual sport or team sport, Qbetween (Qb) = 14.52, df = 1, P = 0.001) and diet control (Qbetween (Qb) = 8.85, df = 1, P = 0.001), explained the heterogeneity of ESs. Our study showed that there was a moderate overall effect of sport-based physical activity intervention on body weight reduction. The team sport type (ES = 1.05, 95% CI = 0.44, 1.66) and diet control group (ES = 0.84, 95% CI = 0.26, 1.41) appeared to be more effective in reducing body weight.  相似文献   

4.
Abstract

The aim of this study was to assess the effect of caffeine ingestion on 8 km run performance using an ecologically valid test protocol. A randomized double-blind crossover study was conducted involving eight male distance runners. The participants ran an 8 km race 1 h after ingesting a placebo capsule, a caffeine capsule (3 mg · kg?1 body mass) or no supplement. Heart rate was recorded at 5 s intervals throughout the race. Blood lactate concentration and ratings of perceived exertion were recorded after exercise. A repeated-measures analysis of variance (ANOVA) identified a significant treatment effect for 8 km performance time (P < 0.05); caffeine resulted in a mean improvement of 23.8 s (95% confidence interval [CI] = 13.1 to 34.5 s) in 8 km performance time (1.2% improvement, 95% CI = 0.7 to 1.8%). In addition, a two-way (time × condition) repeated-measures ANOVA identified a significantly higher blood lactate concentration 3 min after exercise during the caffeine trial (P < 0.05). We conclude that ingestion of 3 mg · kg?1 body mass of caffeine can improve absolute 8 km run performance in an ecologically valid race setting.  相似文献   

5.
Numerous motor abilities depend on the activity of proprioceptors, which has been suggested to be genetically determined. To test this hypothesis, the control of torque generated by knee extensors and knee position was studied in 30 father–son pairs both before and immediately after running. After stabilisation of the participant in a sitting position, the knee joint of his dominant leg was flexed to 90°, and the maximal voluntary torque (MVT) of the dominant knee extensors under static conditions was measured. The participant then tried five times to produce 50% of the MVT. Next, the participant extended the knee to 45° five times without visual control. Significant correlations between the reproducibility of successive trials for groups of fathers and their sons were found. The correlation coefficients for the repeatability of the knee extension torque were 0.69 (confidence interval [CI] = 0.45–0.84; P < 0.01) and 0.75 (CI = 0.54–0.87; P < 0.01) before and after the fatiguing exercise, respectively, whereas the coefficient for the reproducibility of positioning the knee was 0.49 (CI = 0.16–0.72; P < 0.01) after the fatiguing exercise. Our results indicate a significant influence of hereditary factors on the control of limb torque and position.  相似文献   

6.
The purpose of this study was to evaluate the effects of 6 weeks of supramaximal exercise training (SET) on performance variables and metabolic changes in sedentary obese adults.

Twenty-four obese adults were randomly allocated into a non-trained (NT) [n = 12; body mass index (BMI) = 33(3)] and SET group [n = 12; BMI = (33(2)]. After baseline metabolic and fitness measurements, the participants completed a 6-week SET intervention. Metabolic, anthropometric, and fitness assessments were repeated post-intervention.

For SET, fasting glucose (4.64(0.15) vs. 4.32(0.22) mmol · l–1; P < 0.01), insulin (23.2(4.6) vs. 13.8(3.3) µmol · ml–1; P < 0.01), homoeostasis model assessment-insulin resistance index (4.78(1.2) vs. 2.65(1.5); P < 0.01) and systolic blood pressure (127(3) vs. 120(3) mmHg; P < 0.01) were significantly lower 24-h post-intervention than at baseline and for the NT group, and these changes remained significant at 72-h and 2-weeks post-intervention (P < 0.01, respectively). Interestingly, nonesterified fatty acids (0.62(0.09) vs. 0.71(0.11) mmol · l–1; P < 0.01) and resting fat oxidation rate (57(11) vs. 63(4)%; P < 0.01) increased significantly from baseline 24-h post-intervention in the SET group and from baseline at 72-h (P < 0.01, respectively) and 2-weeks post-intervention (P < 0.01, respectively). Six weeks of SET improved a number of metabolic and vascular risk factors in obese, sedentary adults, highlighting the potential of SET to provide an alternative exercise model for the improvement of metabolic health in this population.  相似文献   


7.
Abstract

The purpose of this preliminary investigation was to determine the relative role of the distal lower extremity tissue masses of varsity athletes in predicting distal lower extremity injury sustained during a competitive season. One hundred male and female varsity athletes (basketball, volleyball, soccer, cross country) completed a questionnaire on general health, physiological, and psychosocial variables, during each sport's respective training camp. A series of anthropometric measurements were used as inputs to distal lower extremity tissue mass prediction equations to calculate lean mass, fat mass, bone mineral content and wobbling mass (lean mass + fat mass) and tissue mass ratios. Athletes were monitored throughout their respective seasons and were instructed to report any distal lower extremity injuries to a certified athletic therapist who was responsible for assessing and confirming the reports. Logistic regression analyses were performed to determine which variables significantly predicted distal lower extremity injury. Mean leg fat mass:bone mass (OR = 1.6, CI = 1.0 – 2.5), and competition surface (rubber OR = 8.5, CI = 1.5 – 47.7; artificial turf OR = 4.0, CI = 0.77 – 22.9) were identified as significant predictors of injury. Overall, tibia bone injuries were significantly associated with the ratio of fat mass:bone mineral content and the surface on which the athletes compete.  相似文献   

8.
Abstract

The purpose of this cross-sectional study was to examine the relationship between objectively measured physical activity, sedentary time, and cardiorespiratory fitness in a diverse sample of youth. Participants were recruited from three middle schools and completed assessments of height, weight, cardiorespiratory fitness, and wore an accelerometer for a minimum of four days. Hierarchical general linear models controlling for age, body mass index (BMI) percentile, and sex were used to evaluate the association of time (minutes per day) spent sedentary, and in moderate physical activity and vigorous physical activity with cardiorespiratory fitness (i.e., heart rate response [beats per minute], dependent variable). Results indicated age (β = –0.16, P < 0.05), BMI percentile (β = 0.33, P <0.05), being male (β = 0.17, P < 0.05), sedentary time (β = 0.11, P <0.05), moderate (β = –0.03, P > 0.05) and vigorous (β = –0.22, P < 0.05) physical activity explained 29% of the variance in cardiorespiratory fitness. Evaluation of fitness among high sedentary/high vigorous, high sedentary/low vigorous, low sedentary/low vigorous, and low sedentary/high vigorous groups (defined by the median split) showed that high levels of vigorous activity removed the detrimental effect of high levels of sedentary time on cardiorespiratory fitness. These analyses suggest that the negative impact of sedentary time can be mitigated by engaging in vigorous activity.  相似文献   

9.
Abstract

We examined differences in anthropometry and training between 64 Triple Iron ultra-triathletes competing over 11.4 km swimming, 540 km cycling, and 126.6 km running, and 71 Ironman triathletes competing over 3.8 km swimming, 180 km cycling, and 42.2 km running. The association of anthropometry and training with race time was investigated using multiple linear regression analysis. The Triple Iron ultra-triathletes were smaller (P < 0.05), had shorter limbs (P < 0.05), a higher body mass index (P < 0.05), and larger limb circumferences (P < 0.01) than the Ironman triathletes. The Triple Iron ultra-triathletes trained for more hours (P < 0.01) and covered more kilometres (P < 0.01), but speed in running during training was slower compared with the Ironman triathletes (P < 0.01). For Triple Iron ultra-triathletes, percent body fat (P = 0.022), training volume per week (P < 0.0001), and weekly kilometres in both cycling (P < 0.0001) and running (P < 0.0001) were related to race time. For Ironman triathletes, percent body fat (P < 0.0001), circumference of upper arm (P = 0.006), and speed in cycling training (P = 0.012) were associated with total race time. We conclude that both Triple Iron ultra-triathletes and Ironman triathletes appeared to profit from low body fat. Triple Iron ultra-triathletes relied more on training volume in cycling and running, whereas speed in cycling training was related to race time in Ironman triathletes.  相似文献   

10.
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   

11.
Abstract

This study compared technical actions, movements, heart rates and perceptual responses of selected and unselected youth rugby league players during matches (under-15 to under-17 age groups). The players’ movements and heart rates were assessed using 5 Hz Global Positioning Systems (GPSs), while their technical actions were analysed using video analysis. The maturity of each player was predicted before each season for statistical control. There were no differences (P > 0.05) between selected and unselected players in the under-15 or the under-17 age group for any variables. However, in the under-16 age group, the selected players (57.1 ± 11.9 min) played for longer than the unselected players (44.1 ± 12.3 min; P = 0.017; ES = 1.08 ± CI = 0.87), and covered more distance (5181.0 ± 1063.5 m cf. 3942.6 ± 1108.6 m, respectively; P = 0.012; ES = 1.14 ± CI = 0.88) and high-intensity distance (1808.8 ± 369.3 m cf. 1380.5 ± 367.7 m, respectively; P = 0.011; ES = 1.16 ± CI = 0.88). Although successful carries per minute was higher in the selected under-15 age group, there were no other differences (P > 0.05) in match performance relative to playing minutes between groups. Controlling for maturity, the less mature, unselected players from the under-16 age group performed more high-intensity running (P < 0.05). Our findings question the use of match-related measurements in differentiating between selected and unselected players, showing that later maturing players were unselected, even when performing greater high-intensity running during matches.  相似文献   

12.
This study aimed to verify the prevalence and characteristics of sports injuries (SI) and determine the association between the physical activity level (PA) and SI with perception of health-related quality of life (HRQoL) in Brazilian basketball master athletes. A cross-sectional study was conducted with 410 male master athletes, between 35 and 85 years of age (mean 52.26, SD ±11.83). The HRQoL was assessed using the Medical Outcomes Study – Short Form-36. The PA was evaluated using the International Physical Activity Questionnaire. Information regarding SI was collected using the Reported Morbidity Survey. Poisson regression, as estimated by the prevalence ratio (PR), was used as a measure of the association of PA and SI with HRQoL. The majority of athletes showed a high SI prevalence (58.3%) and reported one injury (67.8%) that occurred during training (61.1%) and primarily affected a lower limb (74.6%). The adjusted regression models showed a positive association of PA with the Functional Capacity (PR = 1.46, 95% confidence interval [CI] = 1.12–1.90) and Physical Component (PR = 1.32, 95% CI = 1.03–1.70) of HRQoL. Furthermore, the SI were negatively associated with HRQoL in Functional Capacity (PR = 1.85, 95% CI = 1.51–2.27), Physical Aspects (PR = 3.99, 95% CI = 3.08–5.18), Pain (PR = 1.65, 95% CI = 1.26–2.16), Social Functioning (PR = 1.79, 95% CI = 1.41–2.27), Emotional Aspects (PR = 4.40, 95% CI = 3.35–5.78), Mental Health domains (PR = 1.37, 95% CI = 1.06–1.68), Physical Component (PR = 2.35, 95% CI = 1.90–2.90) and Mental Component (PR = 2.65, 95% CI = 2.14–3.29). These results highlighted that master athletes showed a high SI prevalence, primarily in the lower limbs. PA positively correlates with the physical HRQoL domain, whereas SI may decrease the HRQoL levels of both physical and mental domains.  相似文献   

13.
We aimed to assess the agreement of a commercially available bioelectrical impedance analysis (BIA) device in measuring changes in fat, lean and bone mass over a 10-week lifestyle intervention, with dual energy X-ray absorptiometry (DXA) as reference. A sample of 136 volunteers (18–66 years) underwent a physical activity intervention to enhance lean mass and reduce fat mass. BIA (Tanita BC545) and DXA (Hologic Explorer) measures of whole-body composition were taken at baseline and at the end of the intervention. After an average of 74 ± 18 days intervention, DXA showed significant changes in 2 of 3 outcome variables: reduced fat mass of 0.802 ± 1.092 kg (P < 0.001), increased lean mass of 0.477 ± 0.966 kg (P < 0.001); minor non-significant increase of 0.007 ± 0.041 kg of bone mass (P = 0.052). The respective changes in BIA measures were a significant reduction of 0.486 ± 1.539 kg fat (P < 0.001), but non-significant increases of 0.084 ± 1.201 kg lean mass (P = 0.425), and 0.014 ± 0.091 kg bone (P = 0.074). Significant, but moderately weak, correlations were seen in absolute mass changes between DXA and BIA: 0.511 (fat), 0.362 (lean) and 0.172 (bone). Compared to DXA, BIA demonstrated mediocre agreement to changes in fat mass, but poor agreement to lean mass changes. BIA significantly underestimated the magnitude of changes in fat and lean mass compared to DXA.  相似文献   

14.
Little is known about the association between environmental characteristics and types of physical activity in adolescents in a Latin American context. The aim of this study was to examine the association between perceived neighborhood environmental characteristics and different types of physical activity in 2,874 adolescents from Joao Pessoa, Paraiba State, Northeastern Brazil. The types of activity measured by questionnaire (≥10 min/day) included sports, physical exercises, active commuting and recreational activities. Neighborhood characteristics were measured by a 15-item scale. Multilevel analyses showed that adolescents who reported “having places they liked to go to” (OR = 1.41; 95%CI: 1.10–1.79) and “places with opportunities to practice” (OR = 1.29; 95%CI: 1.01–1.65) were more likely to play sports. “Seeing interesting things while walking” (OR = 1.24; 95%CI: 1.01–1.53) and “Seeing other adolescents engaged in physical activity” (OR = 1.47; 95%CI: 1,05–2,06) were associated with exercises. “Seeing other adolescents engaged in physical activity” (OR = 1.47; 95%CI: 1.18–1.82), “the neighborhood is not violent” (OR = 1.29; 95%CI: 1.04–1.60) and “having places they like to go to” (OR = 1.59; 95%CI: 1.13–2.25) were positively associated and “places with opportunities to practice” (OR = 0.79; 95%CI: 0.63–0.98) inversely related to active commuting. “Seeing other adolescents engaged in physical activities” (OR = 1.31; 95%CI: 1.05–1.63) and “seeing interesting things while walking” (OR = 1.26; 95%CI: 1.02–1.56) were associated with recreational activities. Neighborhood environmental characteristics associated with the physical activity vary with the type of practices adopted by adolescents.  相似文献   

15.
This study aimed to analyse the association of different components of physical fitness, body composition, cardiometabolic markers and the Mediterranean diet with bone mineral density (BMD) in perimenopausal women, and to test which of these components are independently associated with BMD. The sample comprised 197 perimenopausal women (52.6 ± 4.5 years). Physical fitness was assessed with the “Senior Fitness Test” battery and the handgrip strength and Bruce tests. Fat and lean mass and BMD were measured using dual-energy X-ray absorptiometry. We analysed the markers of metabolic syndrome, C-reactive protein, and components of the Mediterranean diet. Handgrip muscle strength (β = 0.212, P = 0.005), body weight (β = 0.244, P = 0.001), BMI (β = 0.180, P = 0.011) and lean mass (β = 0.379, P < 0.001) were positively associated with BMD. No associations were observed between cardiometabolic markers or the Mediterranean diet with BMD (all P > 0.05). When all relevant indicators of BMD were simultaneously considered, lean mass was the only 1 showing an independent association with BMD (β = 0.392, P < 0.001), explaining 14% of the BMD variability. In conclusion, muscle strength might be a marker of BMD in perimenopausal women. However, lean mass was the only factor independently associated with BMD. Future research to determine whether increasing lean mass through specific exercise-based interventions contributes to increasing BMD is warranted.  相似文献   

16.
This study assesses the longitudinal changes in anthropometric and motor parameters of ski jumpers. Male ski jumpers (n = 329) at various competitive levels participated in this study. These competitors were divided into two groups by age (18 years and younger, and over 18 years), and then divided into seven even intervals within those groups. Basic anthropometric parameters, maximal relative isometric knee extensor force, reaction time, knee extension time, and vertical jump height were measured. The conditions, instruments, and systems of measurement were consistent throughout the study. A reduced body mass index (BMI) in the adult jumpers was significant (P < .01) in the first three (1982–1993) and in the last three (1998–2010) intervals. Adults had an increase of maximal relative isometric knee extensor force (P < .01) in the last three intervals (1998–2010). They had greater maximal relative isometric knee extensor force (with exception of the first interval, 1982–1985) and vertical jump height than younger competitors (P < .01). Both young and adult jumpers exhibited the increase of strength and power in the lower limbs and a decrease in BMI during the whole observed period.  相似文献   

17.
Socio-economic status during childhood has been shown to be a strong predictor of adult health outcome. Therefore, we examined associations of parental educational level, household income and migrant background with physical fitness, spinal flexibility, spinal posture as well as retinal vessel diameters in children of an urban Swiss region. A total of 358 first graders of the Swiss canton Basel-Stadt (age: 7.3, SD: 0.4) were examined. Physical fitness (20 m shuttle run test, 20 m sprint, jumping sidewards and balancing backwards), spinal flexibility and spinal posture (MediMouse®, Idiag, Fehraltdorf, Switzerland) and retinal microcirculation (Static Retinal Vessel Analyzer, Imedos Systems UG, Jena, Germany) were assessed. Parental education, household income, migrant background and activity behaviour were evaluated with a questionnaire. Parental education was associated with child aerobic fitness (P = 0.03) and screen time (P < 0.001). Household income was associated with jumping sidewards (P = 0.009), balancing backwards (P = 0.03) and sports club participation (P = 0.02). Migrant background was associated with BMI (P = 0.001), body fat (P = 0.03), aerobic fitness (P = 0.007), time spent playing outdoors (P < 0.001) and screen time (P < 0.001). For spinal flexibility and retinal vessel diameter, no associations were found (0.06 < P < 0.8). Low parental education, low household income and a migrant background are associated with poor physical fitness, higher BMI and body fat percentage and low-activity behaviour.  相似文献   

18.
Abstract

The purpose of this study was to examine the psychosocial correlates of cardiorespiratory fitness ([Vdot]O2peak) and muscle strength in overweight and obese sedentary post-menopausal women. The study population consisted of 137 non-diabetic, sedentary overweight and obese post-menopausal women (mean age 57.7 years, s = 4.8; body mass index 32.4 kg · m?2, s = 4.6). At baseline we measured: (1) body composition using dual-energy X-ray absorptiometry; (2) visceral fat using computed tomography; (3) insulin sensitivity using the hyperinsulinaemic-euglycaemic clamp; (4) cardiorespiratory fitness; (5) muscle strength using the leg press exercise; and (6) psychosocial profile (quality of life, perceived stress, self-esteem, body-esteem, and perceived risk for developing chronic diseases) using validated questionnaires. Both [Vdot]O2peak and muscle strength were significantly correlated with quality of life (r = 0.29, P < 0.01 and r = 0.30, P < 0.01, respectively), and quality of life subscales for: physical functioning (r = 0.28, P < 0.01 and r = 0.22, P < 0.05, respectively), pain (r = 0.18, P < 0.05 and r = 0.23, P < 0.05, respectively), role functioning (r = 0.20, P < 0.05 and r = 0.24, P < 0.05, respectively), and perceived risks (r = ?0.24, P < 0.01 and r = ?0.30, P < 0.01, respectively). In addition, [Vdot]O2peak was significantly associated with positive health perceptions, greater body esteem, and less time watching television/video. Stepwise regression analysis showed that quality of life for health perceptions and for role functioning were independent predictors of [Vdot]O2peak and muscle strength, respectively. In conclusion, higher [Vdot]O2peak and muscle strength are associated with a favourable psychosocial profile, and the psychosocial correlates of [Vdot]O2peak were different from those of muscle strength. Furthermore, psychosocial factors could be predictors of [Vdot]O2peak and muscle strength in our cohort of overweight and obese sedentary post-menopausal women.  相似文献   

19.
Abstract

Ten healthy, non-cycling trained males (age: 21.2 ± 2.2 years, body mass: 75.9 ± 13.4 kg, height: 178 ± 6 cm, [Vdot]O2PEAK: 46 ± 10 ml · kg?1 · min?1) performed a graded incremental exercise test, two familiarisation trials and six experimental trials. Experimental trials consisted of cycling to volitional exhaustion at 100%, 110% and 120% WPEAK, 60 min after ingesting either 0.3 g · kg?1 body mass sodium bicarbonate (NaHCO3) or 0.1 g · kg?1 body mass sodium chloride (placebo). NaHCO3 ingestion increased cycling capacity by 17% at 100% WPEAK (327 vs. 383 s; P = 0.02) although not at 110% WPEAK (249 vs. 254 s; P = 0.66) or 120% WPEAK (170 vs. 175 s; P = 0.60; placebo and NaHCO3 respectively). Heart rate (P = 0.02), blood lactate (P = 0.001), pH (P < 0.001), [HCO3 ?], (P < 0.001), and base excess (P < 0.001) were greater in all NaHCO3 trials. NaHCO3 attenuated localised ratings of perceived exertion (RPEL) to a greater extent than placebo only at 100% WPEAK (P < 0.02). Ratings of abdominal discomfort and gut fullness were mild but higher for NaHCO3. NaHCO3 ingestion significantly improves continuous constant load cycling at 100% WPEAK due to, in part, attenuation of RPEL.  相似文献   

20.
Abstract

We evaluated (1) the test–retest reliability of the Wingate test conducted on a rowing ergometer, and (2) the sensitivity of this test in determining the differences in performance attained by 12- to 18-year-old rowers. Altogether, 297 male rowers aged 12.0–18.9 years (mean ± s: 14.8 ± 1.7) completed a maximal 30-s test on a rowing ergometer, and 80 rowers representing all age groups were retested after 5–7 days. No change was evident in participants' performance in terms of mean power output (P = 0.726; Cohen's d = 0.04), maximal power output (P = 0.567; Cohen's d = 0.06), and minimum power output (P = 0.318; Cohen's d = 0.11) in the second test. The intra-class correlation coefficients were high (≥0.973) and coefficients of variation were low (≤7.3%). A series of analyses of variance were used to compare the performances among 12- to 18-year-old rowers, and age-related increases in performance were evident (P < 0.001; Cohen's d = 1.91–1.96). The age-related increases in performance were similar, although reduced, when the effects of body mass were partitioned out when using analysis of covariance (P < 0.001; Cohen's d = 0.82–0.85). The results suggest that: (1) the described test is reliable and can be used for maximal-intensity exercise assessment in youth rowing, and (2) it discriminates performance among 12- to-18-year-old rowers.  相似文献   

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