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1.
Nine well-trained, unacclimatized female hockey players performed the Loughborough Intermittent Shuttle Test (LIST) interspersed with three field hockey skill tests in hot (30°C, 38% relative humidity) and moderate (19°C, 51% relative humidity) environmental conditions. Field hockey skill performance declined in both the hot and moderate conditions following 30 and 60?min of the LIST compared with pre-LIST values (P <?0.01). This decrement in performance was compounded in the hot environment with a 6% poorer performance in the heat recorded for the second skill test at 30?min (P <?0.05, hot 101.7?±?3.6 vs moderate 95.7?±?2.9?s; mean ±?s x). However, no difference was found in the decision-making element of the skill test. Fifteen-metre sprint times were slower in the hot condition (P <?0.01). In the hot environment, rectal temperature (P?<?0.01), perceived exertion (P?<?0.05), perceived thirst (P?<?0.01), blood glucose concentration (P?<?0.05) and serum aldosterone concentration (P?<?0.01) were higher. Estimated mean (?±?s x) sweat rate was higher in the hot trial (1.27?±?0.10?l?·?h?1) than in the moderate trial (1.05?±?0.12?l?·?h?1) (P?<?0.05). Body mass was well maintained in both trials. No differences in serum cortisol, blood lactate, plasma volume or plasma ammonia concentrations were found. These results demonstrate that field hockey skill performance is decreased following intermittent high-intensity shuttle running and that this decrease is greater in hot environmental conditions. The exact mechanism for this decrement in performance remains to be elucidated, but is unlikely to be due to low glycogen concentration or dehydration.  相似文献   

2.
Nine well-trained, unacclimatized female hockey players performed the Loughborough Intermittent Shuttle Test (LIST) interspersed with three field hockey skill tests in hot (30 degrees C, 38% relative humidity) and moderate (19 degrees C, 51% relative humidity) environmental conditions. Field hockey skill performance declined in both the hot and moderate conditions following 30 and 60 min of the LIST compared with pre-LIST values (P < 0.01). This decrement in performance was compounded in the hot environment with a 6% poorer performance in the heat recorded for the second skill test at 30?min (P < 0.05, hot 101.7 +/- 3.6 vs moderate 95.7 +/- 2.9 s; mean +/- s(x)). However, no difference was found in the decision-making element of the skill test. Fifteen-metre sprint times were slower in the hot condition (P < 0.01). In the hot environment, rectal temperature (P < 0.01), perceived exertion (P < 0.05), perceived thirst (P < 0.01), blood glucose concentration (P < 0.05) and serum aldosterone concentration (P < 0.01) were higher. Estimated mean ( +/- s(x)) sweat rate was higher in the hot trial (1.27 +/- 0.10 l.h(-1)) than in the moderate trial (1.05 +/- 0.12 l.h(-1)) (P < 0.05). Body mass was well maintained in both trials. No differences in serum cortisol, blood lactate, plasma volume or plasma ammonia concentrations were found. These results demonstrate that field hockey skill performance is decreased following intermittent high-intensity shuttle running and that this decrease is greater in hot environmental conditions. The exact mechanism for this decrement in performance remains to be elucidated, but is unlikely to be due to low glycogen concentration or dehydration.  相似文献   

3.
Abstract

The study investigated the effect of a school-based healthy lifestyles intervention on physical activity and dietary variables. In total 378 children (177 intervention, 201 control; age 9.75 ± 0.82 years (mean ± s)) took part in the 7-month intervention comprising: preparation for and participation in 3 highlight events (a dance festival, a walking event and a running event); an interactive website for pupils, teachers and parents; and vacation activity planners. Primary outcome measures were objectively measured physical activity (pedometers and accelerometers), endurance fitness and dietary variables. Multi-level modelling was employed for data analysis. The increase in physical activity was greater in the intervention group than the control group (steps: 1049 vs 632 daily steps each month; moderate to vigorous physical activity (MVPA) total: 4.6 min · day?1 · month?1 vs 1.3 min · day?1 · month?1; MVPA bouts: 5.4 min · day?1 · month?1 vs 2.6 min · day?1 · month?1; all P < 0.05). The increase in multi-stage fitness test distance was greater for intervention participants (46 vs 29 m · month?1 of intervention, group × month interaction, P < 0.05). There were no differences between groups in dietary variables, body composition, knowledge of healthy lifestyles or psychological variables. Thus an intervention centred around highlight events and including relatively few additional resources can impact positively on the objectively measured physical activity of children.  相似文献   

4.
Abstract

The purpose of this study was to compare the effects of two practical precooling techniques (skin cooling vs. skin + core cooling) on cycling time trial performance in warm conditions. Six trained cyclists completed one maximal graded exercise test ([Vdot]O2peak 71.4 ± 3.2 ml · kg?1 · min?1) and four ～40 min laboratory cycling time trials in a heat chamber (34.3°C ± 1.1°C; 41.2% ± 3.0% rh) using a fixed-power/variable-power format. Cyclists prepared for the time trial using three techniques administered in a randomised order prior to the warm-up: (1) no cooling (control), (2) cooling jacket for 40 min (jacket) or (3) 30-min water immersion followed by a cooling jacket application for 40 min (combined). Rectal temperature prior to the time trial was 37.8°C ± 0.1°C in control, similar in jacket (37.8°C ± 0.3°C) and lower in combined (37.1°C ± 0.2°C, P < 0.01). Compared with the control trial, time trial performance was not different for jacket precooling (?16 ± 36 s, ?0.7%; P = 0.35) but was faster for combined precooling (?42 ± 25 s, ?1.8%; P = 0.009). In conclusion, a practical combined precooling strategy that involves immersion in cool water followed by the use of a cooling jacket can produce decrease in rectal temperature that persist throughout a warm-up and improve laboratory cycling time trial performance in warm conditions.  相似文献   

5.
Purpose: The purpose of this investigation was to examine the effects of a submaximal running warm-up on running performance in male endurance athletes (n = 16, Mage = 21 ± 2 years, MVO2max = 69.3 ± 5.1 mL/kg/min). Method: Endurance performance was determined by a 30-min distance trial after control and submaximal running warm-up conditions in a randomized crossover fashion. The warm-up began with 5 min of quiet sitting, followed by 6 min of submaximal running split into 2-min intervals at speeds corresponding to 45%, 55%, and 65% maximal oxygen consumption (VO2max). A 2-min walk at 3.2 km/hr concluded the 13-min warm-up protocol. For the control condition, participants sat quietly for 13 min. VO2 and heart rate (HR) were determined at Minutes 0, 5, and 13 of the pre-exercise protocol in each condition. Results: At the end of 13 min prior to the distance trial, mean VO2 (warm-up = 14.1 ± 2.2 mL/kg/min vs. control = 5.5 ± 1.7 mL/kg/min) and mean HR (warm-up = 105 ± 11 bpm vs. control = 67 ± 11 bpm) were statistically greater (p < .001) in the warm-up condition compared with the control condition. The distance run did not statistically differ (p = .37) between the warm-up (7.8 ± 0.5 km) and control (7.7 ± 0.6 km) conditions; however, effect size calculation revealed a small effect (d = 0.2) in favor of the warm-up condition. Thus, the warm-up employed may have important and practical implications to determine placing among high-level athletes in close races. Conclusions: These findings suggest a submaximal running warm-up may have a small but critical effect on a 30-min distance trial in competitive endurance athletes. Further, the warm-up elicited increases in physiological variables VO2 and HR prior to performance; thus, a submaximal specific warm-up should warrant consideration.  相似文献   

6.
ABSTRACT

This study investigated effects of total sleep deprivation on self-paced endurance performance, and heart rate (HR) indices of athletes' “readiness to perform”. Endurance athletes (n = 13) completed a crossover experiment comprising a normal sleep (NS) and sleep deprivation (SD) condition. Each required completion of an endurance time-trial (TT) on consecutive days (D1, D2) separated by normal sleep or total sleep deprivation. Finishing time, perceived exertion (RPE), mood, psychomotor vigilance (PVT), and HR responses were assessed. Time on D2 of SD was 10% slower than D2 of NS (64 ± 7 vs 59 ± 4 min, P < 0.01), and 11% slower than D1 of SD (58 ± 5 min, P < 0.01). Subjective to objective (RPE:mean HR) intensity ratio was higher on D2 of SD compared with D2 of NS and D1 of SD (P < 0.01). Mood disturbance and PVT mean response time increased on D2 of SD compared with D2 of NS and D1 of SD. Anaerobic threshold and change in TT time were correlated (R = ?0.73, P < 0.01). Sleep helps to optimise endurance performance. Subjective to objective intensity ratios appear sensitive to effects of sleep on athletes’ readiness. Research examining more subtle sleep manipulation is required.  相似文献   

7.
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   

8.
This study examined the influence of differing volume load and intensity (%1 repetition maximum[%1RM]) resistance exercise workouts on session rating of perceived exertion (sRPE) countermovement jump (CMJ) performance and endocrine responses. Twelve participants performed a workout comprising four exercises (bench press, back squat, deadlift and prone bench pull) in randomised order as either power (POW); 3 sets × 6 repetitions at 45%1RM × 3 min inter-set rest, strength (ST); 3 sets × 3 repetitions at 90%1RM × 3 min inter-set rest, or hypertrophy (HYP); 3 sets × 10 repetitions at 70%1RM × 1 min inter-set rest in a randomised-crossover design. CMJ performance and endocrine responses were measured immediately pre-, post-, 12, 24, 48 and 72 h post-exercise. POW sRPE (3.0 ± 1.0) was lower than ST (4.5 ± 1.0) (P = 0.01), and both were lower than HYP (8.5 ± 1.0) (P = 0.01). Duration of CMJ decrement was longer (P ≤ 0.05) for HYP (72 h) compared to POW (12 h) and ST (24 h). Testosterone concentration was greater (P ≤ 0.05) immediately post-exercise in HYP compared to POW and ST. In conclusion, less inter-set rest, greater volume load and intensity (%1RM) may increase sRPE, duration of CMJ performance decrement and testosterone responses in resistance exercise.  相似文献   

9.
This investigation compared the effects of external pre-cooling and mid-exercise cooling methods on running time trial performance and associated physiological responses. Nine trained male runners completed familiarisation and three randomised 5 km running time trials on a non-motorised treadmill in the heat (33°C). The trials included pre-cooling by cold-water immersion (CWI), mid-exercise cooling by intermittent facial water spray (SPRAY), and a control of no cooling (CON). Temperature, cardiorespiratory, muscular activation, and perceptual responses were measured as well as blood concentrations of lactate and prolactin. Performance time was significantly faster with CWI (24.5 ± 2.8 min; P = 0.01) and SPRAY (24.6 ± 3.3 min; P = 0.01) compared to CON (25.2 ± 3.2 min). Both cooling strategies significantly (P < 0.05) reduced forehead temperatures and thermal sensation, and increased muscle activation. Only pre-cooling significantly lowered rectal temperature both pre-exercise (by 0.5 ± 0.3°C; P < 0.01) and throughout exercise, and reduced sweat rate (P < 0.05). Both cooling strategies improved performance by a similar magnitude, and are ergogenic for athletes. The observed physiological changes suggest some involvement of central and psychophysiological mechanisms of performance improvement.  相似文献   

10.
Abstract

In this study, we compared the effects of accumulated and continuous running on resting arterial blood pressure. Ten normotensive/pre-hypertensive men, aged 25.0 ± 4.2 years (mean ± s), participated in three 2-day trials at least one week apart in a randomized, repeated-measures design. On Day 1, participants rested (control) or ran at 70% of maximum oxygen uptake in either ten 3-min bouts (30 min rest between bouts) or one continuous 30-min bout. On Day 2, participants rested throughout the day. Blood pressure was measured at hourly intervals throughout Days 1 and 2. Mean resting systolic blood pressure on Day 2 was 6% lower during the accumulated and continuous running trials compared with the control trial (110 ± 6 vs. 110 ± 8 vs. 117 ± 6 mmHg respectively; P < 0.05), but there were no differences in resting diastolic blood pressure among the three trials (70 ± 7 vs. 69 ± 6 vs. 70 ± 5 mmHg respectively). These findings demonstrate that accumulating 30 min of running throughout the day in short bouts is as effective as 30 min of continuous running for reducing resting systolic blood pressure on the next day in young normotensive/pre-hyptertensive men.  相似文献   

11.
Abstract

The aim of this study was to objectively quantify ratings of perceived enjoyment using the Physical Activity Enjoyment Scale following high-intensity interval running versus moderate-intensity continuous running. Eight recreationally active men performed two running protocols consisting of high-intensity interval running (6×3 min at 90% [Vdot]O2max interspersed with 6×3 min active recovery at 50% [Vdot]O2max with a 7-min warm-up and cool down at 70% [Vdot]O2max) or 50 min moderate-intensity continuous running at 70% [Vdot]O2max. Ratings of perceived enjoyment after exercise were higher (P < 0.05) following interval running compared with continuous running (88 ± 6 vs. 61 ± 12) despite higher (P < 0.05) ratings of perceived exertion (14 ± 1 vs. 13 ± 1). There was no difference (P < 0.05) in average heart rate (88 ± 3 vs. 87 ± 3% maximum heart rate), average [Vdot]O2 (71 ± 6 vs. 73 ± 4%[Vdot]O2max), total [Vdot]O2 (162 ± 16 vs. 166 ± 27 L) or energy expenditure (811 ± 83 vs. 832 ± 136 kcal) between protocols. The greater enjoyment associated with high-intensity interval running may be relevant for improving exercise adherence, since running is a low-cost exercise intervention requiring no exercise equipment and similar relative exercise intensities have previously induced health benefits in patient populations.  相似文献   

12.
We determined if performance and mechanical running alterations during repeated treadmill sprinting differ between severely hot and hypoxic environments. Six male recreational sportsmen (team- and racket-sport background) performed five 5-s sprints with 25-s recovery on an instrumented treadmill, allowing the continuous (step-by-step) measurement of running kinetics/kinematics and spring-mass characteristics. These were randomly conducted in control (CON; 25°C/45% RH, inspired fraction of oxygen = 20.9%), hot (HOT; 38°C/21% RH, inspired fraction of oxygen = 20.9%; end-exercise core temperature: ~38.6°C) and normobaric hypoxic (HYP, 25°C/45% RH, inspired fraction of oxygen = 13.3%/simulated altitude of ~3600 m; end-exercise pulse oxygen saturation: ~84%) environments. Running distance was lower (P < 0.05) in HOT compared to CON and HYP for the first sprint but larger (P < 0.05) sprint decrement score occurred in HYP versus HOT and CON. Compared to CON, the cumulated distance covered over the five sprints was lower (P < 0.01) in HYP but not in HOT. Irrespective of the environmental condition, significant changes occurred from the first to the fifth sprint repetitions (all three conditions compounded) in selected running kinetics (mean horizontal forces, P < 0.01) or kinematics (contact and swing times, both P < 0.001; step frequency, P < 0.001) and spring-mass characteristics (vertical stiffness, P < 0.001; leg stiffness, P < 0.01). No significant interaction between sprint number and condition was found for any mechanical data. Preliminary evidence indicates that repeated-sprint ability is more impaired in hypoxia than in a hot environment, when compared to a control condition. However, as sprints are repeated, mechanical alterations appear not to be exacerbated in severe (heat, hypoxia) environmental conditions.  相似文献   

13.
Abstract

In the present study, we examined the independent and combined effects of an inspiratory muscle warm-up and inspiratory muscle training on intermittent running to exhaustion. Twelve males were recruited to undertake four experimental trials. Two trials (Trials 1 and 2) preceded either a 4-week training period of 1 × 30 breaths twice daily at 50% (experimental group) or 15% (control group) maximal inspiratory mouth pressure (PImax). A further two trials (Trials 3 and 4) were performed after the 4 weeks. Trials 2 and 4 were preceded by a warm-up: 2 × 30 breaths at 40% PImax. Pre-training PImax and distance covered increased (P < 0.05) similarly between groups after the warm-up (～11% and ～5–7% PImax and distance covered, respectively). After training, PImax increased by 20 ± 6.1% (P < 0.01; d = 3.6) and 26.7 ± 6.3% (P < 0.01; d = 3.1) when training and warm-up were combined in the experimental group. Distance covered increased after training in the experimental group by 12 ± 4.9% (P < 0.01; d = 3.6) and 14.9 ± 4.5% (P < 0.01; d = 2.3) when training and warm-up interventions were combined. In conclusion, inspiratory muscle training and inspiratory muscle warm-up can both increase running distance independently, but the greatest increase is observed when they are combined.  相似文献   

14.
Abstract

The aim of this study was to examine the effect of playing formation on high-intensity running and technical performance during elite soccer matches. Twenty English FA Premier League games were analysed using a multiple-camera computerized tracking system (n = 153 players). Overall ball possession did not differ (P > 0.05) between 4–4–2, 4–3–3 and 4–5–1 formations (50%, s = 7 vs. 49%, s = 8 vs. 44%, s = 6). No differences were observed in high-intensity running between 4–4–2, 4–3–3 and 4–5–1 formations. Compared with 4–4–2 and 4–3–3 formations, players in a 4–5–1 formation performed less very high-intensity running when their team was in possession (312 m, s = 196 vs. 433 m, s = 261 vs. 410 m, s = 270; P < 0.05) but more when their team was not in possession (547 m, s = 217 vs. 461 m, s = 156 vs. 459 m, s = 169; P < 0.05). Attackers in a 4–3–3 performed ～30% more (P < 0.05) high-intensity running than attackers in 4–4–2 and 4–5–1 formations. However, the fraction of successful passes was highest in a 4–4–2 (P < 0.05) compared with 4–3–3 and 4–5–1 formations. The results suggest that playing formation does not influence the overall activity profiles of players, except for attackers, but impacts on very high-intensity running activity with and without ball possession and some technical elements of performance.  相似文献   

15.
The hypothesis, that sailing upwind in wind speeds above 12 knots causes fatigue, which manifests as a reduction in exerted hiking strap force and/or maximal isometric voluntary contraction force (MVC) of the knee extensors, was evaluated. Additionally, it was investigated if a relationship exists between maximal exerted hiking force (hMVC) and sailing performance. In part 1 of the study, 12 national level athletes sailed upwind for 2?×?10?min while hiking strap forces were continuously acquired. Before, in between and after sailing periods, the MVC of the knee extensors was measured. In part 2 of the study, hMVC was measured dry land in a hiking bench and correlated with the overall results at a national championship. Hiking strap force decreased from the first to the last minute in both 10?min sailing periods (430?±?131 vs. 285?±?130?N, P?<?.001 and 369?±?74 vs. 267?±?97 N, P?<?.001, respectively), but MVC was similar before, between and after the two 10?min sailing periods (878?±?215 vs. 852?±?202 vs. 844?±?211 130?N). In part 2, a significant positive correlation (r2?=?0.619, P?<?.01) was observed between hMVC and regatta results. In conclusion, upwind sailing in wind speeds above 12 knots causes sailing-specific fatigue as evidenced by a marked reduction in exerted hiking strap force. However, MVC of the knee extensors was not compromised ～45?s after hiking was terminated. Additionally, sailing performance is related to maximal hiking force.  相似文献   

16.
Abstract

There is little published data in relation to the effects of caffeine upon cycling performance, speed and power in trained cyclists, especially during cycling of ～60 s duration. To address this, eight trained cyclists performed a 1 km time-trial on an electronically braked cycle ergometer under three conditions: after ingestion of 5 mg · kg?1 caffeine, after ingestion of a placebo, or a control condition. The three time-trials were performed in a randomized order and performance time, mean speed, mean power and peak power were determined. Caffeine ingestion resulted in improved performance time (caffeine vs. placebo vs. control: 71.1 ± 2.0 vs. 73.4 ± 2.3 vs. 73.3 ± 2.7 s; P = 0.02; mean ± s). This change represented a 3.1% (95% confidence interval: 0.7–5.6) improvement compared with the placebo condition. Mean speed was also higher in the caffeine than placebo and control conditions (caffeine vs. placebo vs. control: 50.7 ± 1.4 vs. 49.1 ± 1.5 vs. 49.2 ± 1.7 km · h?1; P = 0.0005). Mean power increased after caffeine ingestion (caffeine vs. placebo vs. control: 523 ± 43 vs. 505 ± 46 vs. 504 ± 38 W; P = 0.007). Peak power also increased from 864 ± 107 W (placebo) and 830 ± 87 W (control) to 940 ± 83 W after caffeine ingestion (P = 0.027). These results provide support for previous research that found improved performance after caffeine ingestion during short-duration high-intensity exercise. The magnitude of the improvements observed in our study could be due to our use of sport-specific ergometry, a tablet form and trained participants.  相似文献   

17.
The effectiveness of a nap as a recovery strategy for endurance exercise is unknown and therefore the present study investigated the effect of napping on endurance exercise performance. Eleven trained male runners completed this randomised crossover study. On two occasions, runners completed treadmill running for 30?min at 75% ?O2max in the morning, returning that evening to run for 20?min at 60% ?O2max, and then to exhaustion at 90% ?O2max. On one trial, runners had an afternoon nap approximately 90?min before the evening exercise (NAP) whilst on the other, runners did not (CON). All runners napped (20?±?10?min), but time to exhaustion (TTE) was not improved in all runners (NAP 596?±?148?s vs. CON 589?±?216?s, P?=?.83). Runners that improved TTE after the nap slept less at night than those that did not improve TTE (night-time sleep 6.4?±?0.7?h vs. 7.5?±?0.4?h, P?r2 ? =??0.76, P?=?.001). In runners that improved TTE, ratings of perceived exertion (RPE) were lower during the TTE on NAP than CON compared to runners that did not improve (?0.4?±?0.6 vs. 0?±?0, P?=?.05). Reduced exercising sense of effort (RPE) may account for the improved TTE after the nap. In conclusion, a short afternoon nap improves endurance performance in runners that obtain less than 7?h night-time sleep.  相似文献   

18.
ABSTRACT

As the effect of performance level on sprinting mechanics has not been fully studied, we examined mechanical differences at maximal running speed (MRS) over a straight-line 35 m sprint amongst sprinters of different performance levels. Fifty male track and field sprinters, divided in Slow, Medium and Fast groups (MRS: 7.67 ± 0.27 m?s?1, 8.44 ± 0.22 m?s?1, and 9.37 ± 0.41 m?s?1, respectively) were tested. A high-speed camera (250 Hz) recorded a full stride in the sagittal plane at 30–35 m. MRS was higher (p < 0.05) in Fast vs. Medium (+11.0%) and Slow (+22.1%) as well as in Medium vs. Slow (+10.0%). Twelve, eight and seven out of 21 variables significantly distinguished Fast from Slow, Fast from Medium and Medium from Slow sprinters, respectively. Propulsive phase was signi?cantly shorter in Fast vs. Medium (?17.5%) and Slow (?29.4%) as well as in Medium vs. Slow (?14.4%). Fast sprinters had significantly higher vertical and leg stiffness values than Medium (+44.1% and +18.1%, respectively) and Slow (+25.4% and +22.0%, respectively). MRS at 30–35 m increased with performance level during a 35-m sprint and was achieved through shorter contact time, longer step length, faster step rate, and higher vertical and leg stiffness.  相似文献   

19.
The World Health Organisation’s (WHO) physical activity guidelines recommend 150min/week of moderate- to vigorous-intensity physical activity (MVPA) accumulated in 10 min bouts. To see whether people performing habitual exercise for recreation meet these guidelines, 25 long-distance runners [mean 67 km/wk], 25 joggers [mean 28 km/wk], and 20 sedentary adults wore an ActiGraph GT3X+ accelerometer for 7 days. Sedentary time and bouts were similar in runners and sedentary adults (p > 0.46). Sedentary adults performed 20 ± 16 min/day of MVPA (usual bout duration (W50%): 9.53 ± 3.45min), with joggers and runners performing 45 ± 31min (W50%: 16.92 ± 9.53min) and 83 ± 58min (W50%: 20.35 ± 8.85min), respectively (p ≤ 0.001 versus sedentary group). Data showed that 65% of the sedentary group, 32% of joggers and 4% of long-distance runners did not meet the WHO guideline for MVPA. Failure to meet the guideline was most prominent in, but not restricted to, runners who reported ≤50km running per week. Self-reported running does not ensure adults meet physical activity guidelines or offset daily sedentary behaviours. On the other hand, the sedentary group was very close in accumulating recommended bouts of MVPA in incidental activities. Future studies should assess whether modification of work and leisure physical activity would be more fruitful than encouraging recreational exercise per se in meeting physical activity guidelines.  相似文献   

20.
Purpose: There is an ongoing debate whether highly trained athletes are less responsive to the ergogenic properties of nitrate. We assessed the effects of nitrate supplementation on plasma nitrate and nitrite concentrations and repeated-sprint performance in recreational, competitive and elite sprint athletes. Methods: In a randomized double-blinded cross-over design, recreational cyclists (n?=?20), national talent speed-skaters (n?=?22) and Olympic-level track cyclists (n?=?10) underwent two 6-day supplementation periods; 140?mL/d nitrate-rich (BR; ～800?mg/d) and nitrate-depleted (PLA; ～0.5?mg/d) beetroot juice. Blood samples were collected and three 30-s Wingate tests were performed. Results: Plasma nitrate and nitrite concentrations were higher following BR vs PLA (P?P?>?.10). Peak power over the three Wingates was not different between BR and PLA (1338?±?30 vs 1333?±?30 W; P?=?.62), and there was no interaction between treatment (BR-PLA) and Wingate number (1-2-3; P?=?.48). Likewise, mean power did not differ between BR and PLA (P?=?.86). In contrast, time to peak power improved by ～2.8% following BR vs PLA (P?=?.007). This improvement in BR vs PLA was not different between Wingate 1, 2 and 3. Moreover, the effects of BR vs PLA did not differ between sport levels for any Wingate parameter (all P?>?.30). Conclusion: The plasma and repeated-sprint performance responses to beetroot juice supplementation do not differ between recreational, competitive and elite sprint athletes. Beetroot juice supplementation reduces time to reach peak power, which may improve the capacity to accelerate during high-intensity and sprint tasks in recreational as well as elite athletes.  相似文献   

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