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1.
The purpose of this study was to investigate the effects of a high-intensity free-weight back-squat exercise on postural stability characteristics in resistance-trained males. Eighteen college-aged (mean ± SD: age = 22.9 ± 2.9 years; height = 175.8 ± 6.4 cm; mass = 86.3 ± 9.3 kg), resistance-trained males performed postural stability testing before and after completing five sets of eight repetitions of back-squat exercises at 80% of one-repetition maximum. A commercial balance testing device was used to assess sway index at pre- and at 0, 5, 10, 15 and 20 min post-exercise. Each balance assessment consisted of four, 20-s static stance conditions: eyes-open firm surface, eyes-closed firm surface, eyes-open soft surface and eyes-closed soft surface. Sway index was greater (P = 0.001–0.020) at Post 0 than at all other time points. No differences (P > 0.05) were observed between any other time phases. Sway index was greater (P < 0.001) for eyes-closed soft surface than all other conditions. These findings revealed sway index for all conditions significantly increased following completion of the back-squat; however, sway index recovered within 5 min of exercise. Higher sway index values as a result of neuromuscular fatigue induced by a back-squat exercise may have performance and injury risk consequences to subsequent activities that rely on postural stability. However, these findings suggest balance impairments may recover in ~5 min following high-intensity lower body resistance exercise.  相似文献   

2.
Abstract

Throughout adolescence, swimmers begin to carry out demanding endurance and high-intensity training sets, the effect of which on redox status is largely unknown. The aim of the present study was to investigate the effects of 2000-m continuous swimming and 6 × 50-m maximal swimming on the redox status of adolescent swimmers. Fifteen male and 15 female swimmers, aged 14–18 years, provided blood samples before, immediately after, 1 h after, and 24 h after each exercise for the determination of redox status parameters. Oxidative damage was short-lived and manifest as increases in 8-hydroxy-2?-deoxyguanosine (8-OHdG) 1 h after high-intensity exercise (39%, P < 0.001) and in malondialdehyde immediately after both exercises (65%, P < 0.001). Alterations in antioxidant parameters were sustained during recovery: reduced glutathione decreased 24 h post-exercise (11%, P = 0.001), uric acid increased gradually after high-intensity exercise (29%, P < 0.001) and bilirubin peaked 24 h post-exercise (29%, P < 0.001). Males had higher 8-OHdG (49%, P = 0.001) and uric acid (29%, P < 0.001) concentrations than females. However, females showed higher values of malondialdehyde than males immediately post-exercise (30%, P = 0.039), despite lower pre-exercise values. In conclusion, both endurance and high-intensity exercise perturbed the redox balance without inducing prolonged oxidative damage in trained adolescent male and female swimmers. These swimming training trials were not found to be detrimental to the redox homeostasis of adolescents.  相似文献   

3.
This study investigated whether repeated, very short duration sprints influenced endothelial function (indicated by flow-mediated dilation) and triacylglycerol concentrations following the ingestion of high-fat meals in adolescent boys. Nine adolescent boys completed two, 2-day main trials (control and exercise), in a counter-balanced, cross-over design. Participants were inactive on day 1 of the control trial but completed 40 × 6 s maximal cycle sprints on day 1 of the exercise trial. On day 2, capillary blood samples were collected and flow-mediated dilation measured prior to, and following, ingestion of a high-fat breakfast and lunch. Fasting flow-mediated dilation and plasma triacylglycerol concentration were similar in the control and exercise trial (P > 0.05). In the control trial, flow-mediated dilation was reduced by 20% and 27% following the high-fat breakfast and lunch; following exercise these reductions were negated (main effect trial, P < 0.05; interaction effect trial × time, P < 0.05). The total area under the plasma triacylglycerol concentration versus time curve was 13% lower on day 2 in the exercise trial compared to the control trial (8.65 (0.97) vs. 9.92 (1.16) mmol · l?1 · 6.5 h, P < 0.05). These results demonstrate that repeated 6 s maximal cycle sprints can have beneficial effects on postprandial endothelial function and triacylglycerol concentrations in adolescent boys.  相似文献   

4.
Muscle utilisation in squat exercise depends on technique. The purpose of this study was to compare net joint moments (NJMs) and muscle activation during squats without and with restricted leg dorsiflexion. Experienced men (n = 5) and women (n = 4) performed full squats at 80% one repetition maximum. 3D motion analysis, force platform and (EMG) data were collected. Restricting anterior leg rotation reduced anterior leg (P = 0.001) and posterior thigh (P < 0.001) rotations, resulting in a smaller knee flexion range of motion (P < 0.001). At maximum squat depth, ankle plantar flexor (P < 0.001) and knee extensor (P < 0.001) NJM were higher in unrestricted squats. Hip extensor NJM (P = 0.14) was not different between squat types at maximum squat depth. Vastus lateralis (P > 0.05), vastus medialis (P > 0.05) and rectus femoris (P > 0.05) EMG were not different between squat types. Unrestricted squats have higher ankle plantar flexor and knee extensor NJM than previously reported from jumping and landing. However, ankle plantar flexor and knee extensor NJM are lower in restricted squats than previous studies of jumping and landing. The high NJM in unrestricted squat exercise performed through a full range of motion suggests this squat type would be more effective to stimulate adaptations in the lower extremity musculature than restricted squats.  相似文献   

5.
This study investigated whether haematological markers differ between young and masters marathon participants, running at similar performance levels. Nine young (31.89 ± 4.96 years) and eight masters (63.13 ± 4.61 years) runners participated. At five time points (pre-race through 54 h post-race), a complete blood cell count, basic metabolic panel and creatine kinase (CK) isoenzyme panel were assessed. Race performance was standardised using the World Masters Association Age Grading Performance Tables. Total CK levels were elevated for all participants at all time points post-race (P < 0.001). The CK-isoenzyme MB% was elevated across groups at 6, 30 and 54 h post-race (P < 0.01, P < 0.01 and P < 0.05), with masters runners having a higher CK-MB% at 30 and 54 h (P < 0.05, P < 0.05). Total white blood cell and neutrophil counts were elevated through 6 h post-race (P < 0.001), with higher levels found in younger runners (P < 0.001). When considering all blood work, masters runners had a higher number of abnormal values at 6, 30 and 54 h post-race (P < 0.05, P < 0.01 and P < 0.05). In conclusion, masters runners demonstrated sustained CK-MB elevation, which may suggest greater cardiac stress. However, future studies using additional cardiac markers should be completed to confirm these findings. In addition, masters runners showed an increased number of laboratory values outside normal range, indicating the body’s reduced capacity to respond to marathon running.  相似文献   

6.
This study investigated the evolution of physical and technical performances in the English Premier League (EPL), with special reference to league ranking. Match performance observations (n = 14,700) were collected using a multiple-camera computerised tracking system across seven consecutive EPL seasons (2006–07 to 2012–13). Final league rankings were classified into Tiers: (A) 1st–4th ranking (n = 2519), (B) 5th–8th ranking (n = 2965), (C) 9th–14th ranking (n = 4448) and (D) 15th–20th ranking (n = 4768). Teams in Tier B demonstrated moderate increases in high-intensity running distance while in ball possession from the 2006–07 to 2012–13 season (P < 0.001; effect size [ES]: 0.68), with Tiers A, C and D producing less pronounced increases across the same period (P < 0.005; ES: 0.26, 0.41 and 0.33, respectively). Large increases in sprint distance were observed from the 2006–07 to 2012–13 season for Tier B (P < 0.001; ES: 1.21), while only moderate increases were evident for Tiers A, C and D (P < 0.001; ES: 0.75, 0.97 and 0.84, respectively). Tier B demonstrated large increases in the number of passes performed and received in 2012–13 compared to 2006–07 (P < 0.001; ES: 1.32–1.53) with small-to-moderate increases in Tier A (P < 0.001; ES: 0.30–0.38), Tier C (P < 0.001; ES: 0.46–0.54) and Tier D (P < 0.001; ES: 0.69–0.87). The demarcation line between 4th (bottom of Tier A) and 5th ranking (top of Tier B) in the 2006–07 season was 8 points, but this decreased to just a single point in the 2012–13 season. The data demonstrate that physical and technical performances have evolved more in Tier B than any other Tier in the EPL and could indicate a narrowing of the performance gap between the top two Tiers.  相似文献   

7.
The addition of whey protein to a carbohydrate–electrolyte drink has been shown to enhance post-exercise rehydration when a volume below that recommended for full fluid balance restoration is provided. We investigated if this held true when volumes sufficient to restore fluid balance were consumed and if differences might be explained by changes in plasma albumin content. Sixteen participants lost ~1.9% of their pre-exercise body mass by cycling in the heat and rehydrated with 150% of body mass lost with either a 60 g · L?1 carbohydrate drink (CHO) or a 60 g · L?1 carbohydrate, 20 g · L?1 whey protein isolate drink (CHO-P). Urine and blood samples were collected pre-exercise, post-exercise, post-rehydration and every hour for 4 h post-rehydration. There was no difference between trials for total urine production (CHO 1057 ± 319 mL; CHO-P 970 ± 334 mL; P = 0.209), drink retention (CHO 51 ± 12%; CHO-P 55 ± 15%; P = 0.195) or net fluid balance (CHO ?393 ± 272 mL; CHO-P ?307 ± 331 mL; P = 0.284). Plasma albumin content relative to pre-exercise was increased from 2 to 4 h during CHO-P only. These results demonstrate that the addition of whey protein isolate to a carbohydrate–electrolyte drink neither enhances nor inhibits rehydration. Therefore, where post-exercise protein ingestion might benefit recovery, this can be consumed without effecting rehydration.  相似文献   

8.
Few studies have characterised the immune response to exercise of different intensities and durations in women. In those that have, baseline hormone levels and training status were not always adequately controlled for. Here, leucocyte and cytokine profiles of 11 aerobically trained, eumenorrhoeic females (33 ± 5 years) in the early follicular phase of the menstrual cycle were characterised after 30-min exercise at 3 intensities: 90% lactate threshold (LT), LT, and 110% LT. Proposed cytokine response mediators were quantified: plasma lactate and basal oestradiol concentrations. Intensity-dependent increases occurred in total white blood cells and lymphocyte counts (P < 0.001). Elevated plasma IL-6 and IL-1ra concentrations post-exercise [F = 12.38, P < 0.01 and F = 7.65, P < 0.05, respectively] were not intensity-dependent, indicating that cytokine release may be better associated with exercise duration than intensity in trained women. Changes in plasma IL-1ra and basal oestradiol (ρ = ?0.893, P < 0.01) were correlated at intensities above LT only. These findings suggest a role for plasma sex hormones in moderating the exercise-induced immune response in women. However, the associations observed did not account for the magnitude of the cytokine response observed, and future studies should explore contributions of other potential mediators following short-duration exercise.  相似文献   

9.
The objective of the present study was to investigate the effects of combined training without caloric restriction on inflammatory markers in overweight girls. Thirty-three girls (13–17 years) were assigned into overweight training (n = 17) or overweight control (n = 16) groups. Additionally, a normal-weight group (n = 15) was used as control for the baseline values. The combined training programme consisted of six resistance exercises (three sets of 6–10 repetitions at 60–70% 1 RM) followed by 30 min of aerobic exercise (walking/running) at 50–80% VO2peak, performed in the same 60 min session, 3 days/weeks, for 12 weeks. Body composition, dietary intake, aerobic fitness (VO2peak), muscular strength (1 RM), glycaemia, insulinemia, lipid profile and inflammatory markers (C-reactive protein, interleukin-6, tumour necrosis factor-alpha, interleukin-10, leptin, resistin and adiponectin) were measured before and after intervention. There was a significant decrease in body fat (P < 0.01) and increase in fat-free mass (P < 0.01), VO2peak (P < 0.01), 1 RM for leg press (P < 0.01) and bench press (P < 0.01) in the overweight training group. Concomitantly, this group presented significant decreases in serum concentrations of C-reactive protein (P < 0.05) and leptin (P < 0.05), as well as in insulin resistance (P < 0.05) after the experimental period. In conclusion, 12 weeks of combined training without caloric restriction reduced inflammatory markers associated with obesity in overweight girls.  相似文献   

10.
Abstract

We investigated the effects of an acute bout of exercise on serum soluble leptin receptor (sOB-R) concentrations. Eighteen male participants completed two different exercise sessions with intensities of 25% and 65% maximal aerobic capacity (VO2max). In addition to the energy expenditure during exercise sessions being measured, blood samples were collected before exercise, and immediately, at 24 h, and at 48 h post-exercise to analyse sOB-R, leptin and insulin levels. At 24 h post-exercise, sOB-R and leptin concentrations at the 65% VO2max were significantly different from those at the 25% VO2max. Leptin levels at 48 h post-exercise were also significantly lower for the 65% VO2max than for the 25% VO2max (P < 0.01). In the 65% VO2max session, the energy expenditure during exercise was significantly associated with leptin concentrations at 24 h and 48 h and sOB-R concentrations at 24 h post-exercise. However, no correlations were found between sOB-R and leptin at the three post-exercise time points. In conclusion, an acute bout of exercise with 920 kcal of output resulted in an increase in sOB-R levels at 24 h post-exercise. However, the changes in sOB-R levels due to an acute bout of exercise might not contribute to the delayed decrease observed for leptin.  相似文献   

11.
Abstract

This prospective cohort study described return-to-play (RTP) data for different types of muscle injuries in male elite-level football players in Europe. Eighty-nine European professional teams were followed between 2001 and 2013. Team medical staff recorded individual player exposure and time-loss injuries. A total of 17,371 injuries occurred, including 5603 (32%) muscle injuries. From 2007, we received results from 386 magnetic resonance imaging (MRI) examinations, and radiological grading was performed. A negative MRI was associated with shorter recovery time (6 ± 7 days). Lay-off days were correlated with MRI grading of thigh muscle injuries (P < 0.001). Among hamstring injuries, 83% occurred to the biceps femoris, 12% affected the semimembranosus and 5% the semitendinosus. Recurrence rate was higher among biceps femoris injuries (18%) compared with semitendinosus and semimembranosus injuries (2% together). Groin muscle injuries caused shorter median absence (9 days) than hamstring (13 days; P < 0.001), quadriceps (12 days; P < 0.001) and calf muscle (13 days; P < 0.001) injuries. Overall, we found that MRI was valuable for prognosticating RTP, with radiological grading associated with lay-off times after injury. Re-injuries were common in biceps femoris injuries but rare in semitendinosus and semimembranosus injuries.  相似文献   

12.
Acute exercise reduces postprandial triacylglycerol concentrations ([TAG]) in boys and girls; however, it is not known whether between-sex differences exist in response to exercise. Fifteen boys (mean(SD): 11.8(0.4) years) and sixteen girls (12.1(0.7) years) completed two, 2-day conditions. On day 1, participants rested (CON) or completed 10 × 1 min high-intensity interval runs at 100% maximal aerobic speed with 1 min recovery (HIIR). On day 2, participants consumed a standardised breakfast and lunch over a 6.5-h period during which seven capillary blood samples were collected. Based on ratios of the geometric means (95% CI for ratios), fasting [TAG] was 32% lower in boys than girls (?44 to ?18%, ES = 1.31, P < 0.001), and 12% lower after HIIR than CON (?18 to ?5%, ES = 0.42, P = 0.003); the magnitude of reduction was not significantly different between the sexes (8% (ES = 0.36) vs. 15% (ES = 0.47), respectively; P = 0.29). The total area under the [TAG] versus time curve was 27% lower in boys than girls (?40 to ?10%, ES = 1.02, P = 0.005), and 10% lower after HIIR than CON (?16 to ?5%, ES = 0.36, P = 0.001); the magnitude of reduction was similar between the sexes (11% (ES = 0.43) vs. 10% (ES = 0.31), respectively; P = 0.87). The small-moderate reduction in postprandial [TAG] after HIIR was similar between the sexes.  相似文献   

13.
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   

14.
ABSTRACT

Purpose: The effect of breakfast omission on evening high-intensity exercise performance has not previously been studied. Methods: In a randomised and counterbalanced cross-over design, 10 competitive rowers (2 male, 8 female; mean?±?SD: age 21?±?2 y, height 176?±?7?cm, weight 76?±?12?kg, body fat 19.7?±?6.8%) completed two trials (individualised carbohydrate-rich breakfast (BT; 831?±?67?kcal eaten before 09:00) and no-breakfast (NBT; extended overnight fast until 12:00)). Following ad libitum afternoon food intake, participants completed a 2000-m time-trial on a rowing ergometer between 16:30 and 18:00. Appetite and energy intake were measured throughout the day, whilst power output, time, heart rate, blood lactate, blood glucose and RPE were assessed during the time trial. Results: Appetite ratings were higher throughout the morning in NBT compared with BT, but there were no differences in ratings in the afternoon. Energy intake at lunch was greater NBT compared with BT (1236?±?594 vs 836?±?303?kcal, p?<?.05), which partly compensated for breakfast omission, although overall energy intake tended to be lower in NBT compared with BT (1236?±?594 vs 1589?±?225?kcal, p?=?.08). The time taken to complete the 2000-m time trial was greater in NBT compared with BT (469.2?±?43.4 vs 465.7?±?43.3?s; p?<?.05). No differences in heart rate, blood glucose and blood lactate responses were apparent, but overall RPE was higher in NBT compared with BT (17.8?±?0.9 vs 16.7?±?0.7?au, p?<?.05). Conclusion: The omission of a carbohydrate-rich breakfast impaired evening performance during a 2000-m rowing time trial. This finding has implications for optimising evening high-intensity exercise performance.  相似文献   

15.
Abstract

The purpose of this study was to analyse the effect of regular exercise on spleen and peritoneal exudate reactive oxygen species (ROS) and lymphocyte proliferation by splenocytes. Twenty-four female BALB/c mice were randomly divided into trained (n = 12) and untrained (n = 12) groups. These two groups were further divided into mice that were studied at rest (trained/rest, n = 5; untrained/rest, n = 6) and immediately after a 2 h acute bout of exercise (trained/exercise, n = 6; untrained/exercise, n = 6). The animals were bred in the animal facility of the Yonsei University College of Medicine, where they were housed in a temperature- (22 – 24°C) and humidity- (50 – 60%) controlled environment, with a 12 h photoperiod, and provided with food and water ad libitum. The trained mice underwent 10 weeks of endurance swimming training (5 days per week) in water at 26 – 29°C for 60 min. Changes in body mass, proliferative activity and the production of reactive oxygen species from spleen lymphocytes and peritoneal exudate cells were determined. The splenic lymphocytes of the trained mice had much greater proliferative activity than those of the untrained mice (P < 0.05). Trained mice had lower ROS production in splenic lymphocytes and peritoneal exudate cells than untrained mice. In both groups, there was substantial inhibition of proliferative activity stimulated with medium, concanavalin A and lipopolysaccharide following the acute bout of exercise. This may have been caused by excessive ROS production following the acute exercise session.  相似文献   

16.
Abstract

Ghrelin is a hormone that stimulates hunger. Intense exercise has been shown to temporarily suppress hunger after exercise. In the present study, we investigated whether post-exercise hunger suppression is mediated by reduced plasma total ghrelin concentrations. Nine men and nine women participated in the study. Their mean physical characteristics were as follows: age 24.8 (s x  = 0.9) years, body mass index 22.9 (s x  = 0.6) kg · m?2, maximal oxygen uptake ([Vdot]O2max) 57.7 (s x  = 2.2) ml · kg?1 · min?1. The participants completed two 3-h trials (exercise and control) on separate days in a randomized balanced design after overnight fasts. The exercise trial involved a 1-h treadmill run at 73.5% of [Vdot]O2max followed by 2 h of rest. The control trial consisted of 3 h of rest. Blood samples were collected at 0, 0.5, 1, 1.5, 2, and 3 h. Total ghrelin concentrations were determined from plasma. Hunger was assessed following blood sampling using a 15-point scale. The data were analysed using repeated-measures analysis of variance. Hunger scores were lower in the exercise trial than in the control trial (trial, P = 0.009; time, P < 0.001; trial × time, P < 0.001). Plasma total ghrelin concentrations did not differ between trials. These findings indicate that treadmill running suppresses hunger but this effect is not mediated by changes in plasma total ghrelin concentration.  相似文献   

17.
Abstract

Physiological responses and performance were examined during and after a simulated trampoline competition (STC). Fifteen elite trampoline gymnasts participated, of which eight completed two routines (EX1 and EX2) and a competition final (EX3). Trampoline-specific activities were quantified by video-analysis. Countermovement jump (CMJ) and 20 maximal trampoline jump (20-MTJ) performances were assessed. Heart rate (HR) and quadriceps muscle temperature (Tm) were recorded and venous blood was drawn. A total of 252 ± 16 jumps were performed during the STC. CMJ performance declined (P < 0.05) by 3.8, 5.2 and 4.2% after EX1, EX2 and EX3, respectively, and was 4.8% lower (P < 0.05) than baseline 24 h post-competition. 20-MTJ flight time was ~1% shorter (P < 0.05) for jump 1–10 after EX2 and 24 h post STC. Tm increased (P < 0.05) to ~39°C after the warm-up, but declined (P < 0.05) 1.0 and 0.6ºC before EX2 and EX3, respectively. Peak HR was 95–97% HRmax during EX1-3. Peak blood lactate, plasma K+ and NH3 were 6.5 ± 0.5, 6.0 ± 0.2 mmol · l?1 and 92 ± 10 µmol · l?1, respectively. Plasma CK increased (P < 0.05) by ~50 and 65% 0 and 24 h after STC. In conclusion, a trampoline gymnastic competition includes a high number of repeated explosive and energy demanding jumps, which impairs jump performance during and 24 h post-competition.  相似文献   

18.
This study investigated (i) the prevalence of hypohydration and (ii) association between urinary indices of hydration status and confounding factors (e.g., urine protein content, water intake) in elite youth boxers during their weight-stable phase before competition. Sixteen national champion boxers (all male, 17 ± 1 y) were measured on 3 occasions (baseline, day 3, day 10), 30-day prior to competition. Body mass, total body water, urine specific gravity (USG), osmolality (UOSM) and total protein content (TPC) were evaluated to determine hydration status and fluid balance. Overall macronutrient and water intake were assessed using dietary records. Both UOSM and USG increased from day 3 to day 10 by 16% and 0.4% (P < 0.001), despite athletes being in their weight-stability period, and regardless of ad libitum fluid intake. Hypohydration was universally prevalent among all athletes on both test days with USG: 1.027 ± 0.003 g · mL?1 and UOSM: 1035 ± 108 mOsmol · kg?1. An inverse association between mean UOSM values and mean water intake was observed (R = ?0.52, P = 0.04), while TPC was not associated with any urinary dehydration markers (USG, P = 0.51; UOSM, P = 0.61). The present outcomes find that the most prevalent urinary dehydration markers used to classify hydration status in competition exhibit large variability, even during weight-stable periods.  相似文献   

19.
Abstract

The aim of this study was to assess the effects of cold-water immersion (cryotherapy) on indices of muscle damage following a bout of prolonged intermittent exercise. Twenty males (mean age 22.3 years, s = 3.3; height 1.80 m, s = 0.05; body mass 83.7 kg, s = 11.9) completed a 90-min intermittent shuttle run previously shown to result in marked muscle damage and soreness. After exercise, participants were randomly assigned to either 10 min cold-water immersion (mean 10°C, s = 0.5) or a non-immersion control group. Ratings of perceived soreness, changes in muscular function and efflux of intracellular proteins were monitored before exercise, during treatment, and at regular intervals up to 7 days post-exercise. Exercise resulted in severe muscle soreness, temporary muscular dysfunction, and elevated serum markers of muscle damage, all peaking within 48 h after exercise. Cryotherapy administered immediately after exercise reduced muscle soreness at 1, 24, and 48 h (P < 0.05). Decrements in isometric maximal voluntary contraction of the knee flexors were reduced after cryotherapy treatment at 24 (mean 12%, s x  = 4) and 48 h (mean 3%, s x  = 3) compared with the control group (mean 21%, s x  = 5 and mean 14%, s x  = 5 respectively; P < 0.05). Exercise-induced increases in serum myoglobin concentration and creatine kinase activity peaked at 1 and 24 h, respectively (P < 0.05). Cryotherapy had no effect on the creatine kinase response, but reduced myoglobin 1 h after exercise (P < 0.05). The results suggest that cold-water immersion immediately after prolonged intermittent shuttle running reduces some indices of exercise-induced muscle damage.  相似文献   

20.
Abstract

The aim of this study was to investigate the effects of a single bout of whole-body vibration (WBV) on running gait. The running kinematic of sixteen male marathon runners was assessed on a treadmill at iso-efficiency speed after 10 min of WBV and SHAM (i.e. no WBV) conditions. A high-speed camera (210 Hz) was used for the video analysis and heart rate (HR) was also monitored. The following parameters were investigated: step length (SL), flight time (FT), step frequency (SF), contact time (CT), HR and the internal work (WINT). Full-within one-way analysis of variance (ANOVA) of the randomised crossover design indicated that when compared to SHAM conditions, WBV decreased the SL and the FT by ~4% (P < 0.0001) and ~7.2% (P < 0.001), respectively, and increased the SF ~4% (P < 0.0001) while the CT was not changed. This effect occurred during the first minute of running: the SL decreased ~3.5% (P < 0.001) and SF increased ~3.3% (P < 0.001). During the second minute the SL decreased ~1.2% (P = 0.017) and the SF increased ~1.1% (P = 0.02). From the third minute onwards, there was a return to the pre-vibration condition. The WINT was increased by ~4% (P < 0.0001) during the WBV condition. Ten minutes of WBV produced a significant alteration of the running kinematics during the first minutes post exposure. These results provide insights on the effects of WBV on the central components controlling muscle function.  相似文献   

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