摘要:

Two female and six male athletes performed three loaded (18 kg) countermovement jump squats with and without the use of a dampener system designed to reduce the impact force of landing. The peak vertical ground reaction force was recorded in both conditions. The peak impact force was significantly (p≤0.01) reduced by 29%, from 3.4 to 2.6 times body weight, by the dampener mechanism. The use of dampeners had no effect on the peak concentric velocity of the jump or jump height attained. The dampening function occurred without impeding concentric performance of the jumps and should reduce the incidence of injury associated with high‐intensity plyometric exercises. Such a force‐attenuating mechanism would appear to have considerable application in rehabilitation and potentially may be used to allow athletes to perform plyometric training safely with a heavier load than has previously been possible.

ISSN:1057-8315    

DOI:10.1080/15438629309511978

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

The objective of this investigation was to determine the effect of a daily intake of fluid and salt supplementation (FSS) on the body mass change of 30 endurance‐trained male volunteers 21 to 25 years old, with an average maximum oxygen uptake of 65 ml.kg‐l, min‐1, during 364 days of hypokinesia (decreased number of steps taken per day). The volunteers were divided into three equal groups: group 1 pursued normal ambulatory life (control subjects); group 2 was subjected to pure hypokinesia (HK), that is, without the use of FSS (hypokinetic subjects); and group 3 submitted to HK and consumed daily 26 ml/kg body weight of water and 0.15 g/kg body weight of sodium chloride (NaCl) in small doses (200 ml saline/hr) (hyperhydrated subjects). For the simulation of the hypokinetic effect, groups 2 and 3 were kept to an average of 3000 walking steps/day. All men prior to their exposure to HK were on average running 10,000 steps/day. During the study period the change in body mass of human body segments was determined using a gamma scanning method. A significant change was observed in the body mass of all hypokinetic subjects (group 2). The least pronounced change in body mass was in the hyperhydrated volunteers (group 3). In the hypokinetic volunteers the amount of adipose tissue increased significantly, mainly in the middle part of the trunk and thighs, and the amount of muscle tissue decreased significantly in the antigravity muscles of the back, some muscles of the pelvic girdle, and in the legs. It was concluded that chronic hyperhydration may be used to attenuate the loss of body mass during prolonged restriction of muscular activity.

ISSN:1057-8315    

DOI:10.1080/15438629309511979

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

Computerized echocardiography at rest was used to follow up the dynamics of left heart enlargement in adolescent ice hockey players aged 11 to 15 years. The first year of strength‐endurance training did not lead to any remarkable change of echocardiographic parameters of the left heart ventricular size. A slight tendency to left ventricular hypertrophy appeared after 2 years of training, becoming more marked and significant after the third and fourth years of training. First signs of dilation of the left ventricle were observed after 3 year of training, but it was only after the fourth year of training that there appeared significant evidence. The measured absolute value and the value relative to anthropometric parameters generally produced the same results with a slightly different significance between specifically compared variables. A measurable physiologic enlargement of the heart following regular ice hockey training may be expected in adolescent boys after 3 to 4 years of training.

ISSN:1057-8315    

DOI:10.1080/15438629309511980

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

This study investigated the relationships between physical fitness, cognitive performance, and age. Sixty adults, ranging in age from 18 to 90 years, participated in the study. Physical fitness was assessed using an incremental exercise stress protocol. A modified Stroop paradigm consisting of four different tasks with varying degrees of cognitive effort was used to evaluate cognitive performance. A Pearson product moment correlation was used first to evaluate the relationship between age and cognitive performance and secondly the relationship between physical fitness and the cognitive variables. Results revealed a significant correlation (p≤0.001) between age and each cognitive variable. The magnitude of the correlation increased as the attentional demand of the task increased. The correlation between physical fitness and cognition revealed a significant correlation (p≤0.05) for two of the four cognitive variables studied. A negative correlation existed between fitness and response time and the magnitude of the correlation between fitness and cognition increased as the attentional demand of each specific task increased. The results support a hypothesis that a degree of fitness in a subject potentiates performance in a mentally demanding task.

ISSN:1057-8315    

DOI:10.1080/15438629309511981

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

To characterize fluid and ion shifts during a 4‐week cold adaptation period, six nonadapted volunteers underwent a cold acclimation program (CAP), which consisted of 1 hour head‐out immersion in water 14±1°C three times a week. Blood samples were analyzed before and after immersion in the first and last weeks of CAR Urine was collected for 10 hours before, during, and for 3 hours after immersion. Plasma volume (PV) decreased during the first immersion (‐18%) and less after CAP (‐12%). Blood volume reduction was 8.5% before and 5.2% after CAP. Mean corpuscular volume was not changed either after the cold exposure or after the cold adaptation. The concentration of serum proteins increased by 12.1% after first immersion and by 8.1% after CAP. The changes in serum concentration of Na+, K+, and Cl‐before and after CAP were not significant. Urine flow increased by 97% after the first immersion, and by 165% after CAR Urinary excretion of Na+increased by 65% and 184% and of K+, by 122% and 262% during first immersion and after CAP, respectively. Serum concentration of aldosterone increased nonsignificantly (+30%) during immersion before CAP and it did not change after CAR A significant reduction in PV and an increased diuresis and elevated excretion of cations occurred after CAP.

ISSN:1057-8315    

DOI:10.1080/15438629309511982

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

Theobromine ingestion (100 mg/kg body weight) did not affect resting plasma fatty acid concentration in untrained rats, whereas fatty acid concentration was higher (p≤0.001) following exhaustive treadmill exercise in the theobromine group (0.67±0.08 mM, mean±SEM) than in the controls (0.31±0.10 mM). Run time to exhaustion was also greater (p≤0.02) for the theobromine rats (44.0±6.9 min) compared with control animals (27.5±3.5 min). Liver glycogen utilization rate was lower (p≤0.05) for the theobromine animals than the controls (4.58±0.46 vs. 6.75±0.92μmol/g/min, respectively), as was soleus muscle glycogen use (p≤0.03; 0.40±0.04 vs. 0.53±0.04μmol/g/min, respectively). This suggests that theobromine increases exercise performance by reducing glycogen use and enhancing free fatty acid availability to the working muscle.

ISSN:1057-8315    

DOI:10.1080/15438629309511983

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

Examination of 36 top athletes after a period of prolonged training revealed a significantly reduced serum uric acid concentration measured both before cycle ergometry exercise and in the 3rd and 10th minutes of recovery after exercise. Regression and correlation analysis showed a significant indirect relationship between maximum oxygen consumption and serum uric acid concentration obtained before exercise and during the 3rd and 10th minutes of recovery after exercise. Thus, endurance training had a positive influence on serum uric acid concentration. These findings may be used for testing functional efficiency and training ability of athletes, particularly in long‐term investigations. It is assumed that the ability to reduce serum uric acid concentration by a suitable physical activity could be used also in appropriate patients with hyperuricemia.

ISSN:1057-8315    

DOI:10.1080/15438629309511984

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

摘要:

This literature review has attempted to determine whether marital and family factors are important within each of the following psychosocial aspects of a cardiac rehabilitation program mainly for men, but also for some women groups: social support, well‐being, stress management, depression and anxiety control, return to work, modification of alcohol or substance abuse, and sexual adjustment. A summary of convincing research in the general population is presented that suggests marital and family factors play a crucial role in coping within each of these psychosocial areas. The specific cardiac literature was found to contain convincing theoretical, clinical, and nonexperimental reports to justify emphasizing family factors in promoting psychosocial adjustment in heart patients. However, with only a few noteworthy exceptions, the cardiac literature was found, generally, to lack well‐controlled comparison studies that employed objective measures for evaluation of family‐system variables contributing to effective cardiac rehabilitation. Some recommendations for future researchers interested in examining family‐system aspects of cardiac rehabilitation are offered.

ISSN:1057-8315    

DOI:10.1080/15438629309511985

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

ISSN:1057-8315    

DOI:10.1080/15438629309511986

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor

ISSN:1057-8315    

DOI:10.1080/15438629309511977

出版商:Taylor&Francis Group    

年代:1993

数据来源: Taylor