摘要:

This is a case‐control study on the relationship between strength of the hamstrings and quadriceps muscle and running injuries. Sixteen male runners, who had sustained a medically treated running injury during the year prior to this study, were matched for weekly running distance and age with 16 male noninjured control runners. All subjects were fit at the time of measurement. Hamstring (H) and quadriceps (Q) strength torque was measured isometrically at knee angles of 45°and 60°, respectively. The absolute torque value was used to analyze the difference in strength between muscles in injured subjects. The torque value relative to body weight was used to analyze the difference between injured and noninjured runners. Also the H/Q ratio was calculated. In injured subjects all measurements showed no significant (p>0.05) difference between the injured and noninjured side of the body. A previously injured runner showed a trend to have a higher isometric H and Q torque value relative to body weight in comparison with a noninjured control runner. This trend even proved significant when the mean isometric quadriceps torque of the left leg (p<0.05) and the right leg (p<0.01) of a noninjured runner was compared with the mean isometric quadriceps torque of the injured leg of a runner. No such trend was found with regard to the H/Q ratio. These findings do not support the hypothesis that muscle strength imbalance will lead to a running injury, nor do they support the hypothesis that due to the mechanics of running the H tends to strengthen relatively more than the Q muscle. Also the hypothesis that an injured runner tends to have weaker H and Q muscles than noninjured runners was not confirmed. However, both the retrospective and the case‐control approach to the problem has its limitations. The“true”relationship between muscular imbalance or muscular weakness and running injury can only be clarified by a prospective study in which at baseline all possible internal and external risk factors for running injury are registered carefully.

ISSN:1057-8315    

DOI:10.1080/15438629409512004

出版商:Taylor&Francis Group    

年代:1994

数据来源: Taylor

摘要:

The human body involves the complex interaction between many feedback systems. This is certainly indicative that we are basically a nonlinear organism. Recent developments in the understanding of nonlinear systems suggest that fractal (power law) relationships may be the rule, not the exception. In this article it is shown that the performance of male and female superior athletes exhibits a fractal relationship between world record running and swimming times and the distance of the event. Furthermore, the precision of this relationship is so accurate that the small deviations exhibited by data from a fractal fit might be explained using the dominant interplay between aerobic and anaerobic energy expenditure.

ISSN:1057-8315    

DOI:10.1080/15438629409512005

出版商:Taylor&Francis Group    

年代:1994

数据来源: Taylor

摘要:

The purpose of this study was to compare stair‐step ergometry to walk/run training in terms of improving cardiorespiratory fitness and reducing adiposity in previously sedentary men (mean±SE: age, 48.2±1.4 yr; height, 175.7±1.4 cm; weight, 92.9±4.4 kg; body fat, 27.6±2.0%). Two groups of five men each trained (14 weeks, 3 to 4 day/week, 30 to 45 min/day) by either stair‐step ergometry or walk/run exercise, while a third group of seven men served as sedentary controls. Relative and absolute maximal oxygen uptake improved by≈20% (p<0.05) in both exercise groups. Time to exhaustion during an incremental treadmill test also increased similarly by≈3.3 minutes (≈30%; p<0.05) regardless of the training mode. Fat mass (≈3 kg) was significantly (p<0.05) reduced with both training methods. These data suggest that stair‐step ergometry and walk/ run training improve cardiorespiratory fitness and reduce adiposity to a similar degree in previously sedentary, somewhat overweight men.

ISSN:1057-8315    

DOI:10.1080/15438629409512006

出版商:Taylor&Francis Group    

年代:1994

数据来源: Taylor

摘要:

The purpose of this study was to determine the relationship of both sport classification and gender to injury in the athlete with cerebral palsy (CP). Of 217 participants, 54 (25%) reported an injury episode. A relationship between both gender and sport classification to injury (p = 0.001) was discovered. For the nonambulatory, a female was more likely than a male to have an injury, and for the ambulatory, a male was more likely than a female to have an injury. For the nonambulatory, a female had a greater number of injuries to the shoulder, hand/finger, and knee compared with the male. For the ambulatory, the male had a greater frequency of injury to the shoulder, knee, and leg/ankle region. Sport participation for the athlete with CP is largely an adult phenomenon (mean age, 24.23 years) with a late introduction to begin sports activity (mean age, 18 years). This may impede the development of sport skills and result in improper mechanics of movement that may lead to injury. An aggressive approach to the treatment and rehabilitation of an injury episode is warranted by all medical professionals.

ISSN:1057-8315    

DOI:10.1080/15438629409512007

出版商:Taylor&Francis Group    

年代:1994

数据来源: Taylor

摘要:

Four male and five female elderly subjects (ages 62 to 82 years) participated in this study to determine the effect of cutaneous neuromuscular electrical stimulation (NMES) on quadriceps and hamstring peak isometric and isokinetic torque production. Following habituation, subjects performed voluntary isometric and isokinetic (1.05, 1.57, and 2.09 rad.s‐1) quadriceps and hamstring contractions with and without NMES on a Kin‐Com dynamometer. Tests were performed on 4 separate days and randomized for muscle group, contraction velocity, and NMES application. The maximal tolerable level of NMES (symmetrical biphasic waveform, 0.250 msec duration, 50 pps) was applied via two pairs of surface electrodes each placed over motor points of the quadriceps and hamstring muscles. Peak torque produced with NMES alone ranged from only 1 to 20% maximum voluntary isometric contraction. For both muscle groups, there were no significant differences (p>0.05) in either peak isometric or isokinetic torque between voluntary effort with and without NMES. Reasons for the lack of benefit of voluntary plus NMES effort on peak quadriceps and hamstring isometric and isokinetic torque may include: (1) a poor tolerance of the elderly subjects to NMES, or (2) an adequate ability of the elderly subjects to recruit motor units during voluntary effort alone. Regardless, these data imply that voluntary isometric and isokinetic quadriceps and hamstring contractions supplemented with NMES did not result in the additional recruitment of motor units in these nonimpaired elderly subjects.

ISSN:1057-8315    

DOI:10.1080/15438629409512008

出版商:Taylor&Francis Group    

年代:1994

数据来源: Taylor

摘要:

Seven male competitive road cyclists were studied to assess their self‐selected dietary carbohydrate intake and to determine whether immediate post‐training glucose supplementation could improve cycling performance 24 hours later. A random order, double‐blind crossover design was used. Subjects cycled to exhaustion at 75% maximal oxygen uptake VO2maxand consumed a 12% maltodextrin (3.0 g CHO‐kg‐1body weight) (CHO) or placebo (PLA) solution immediately postexercise. After 24 hours, the subjects cycled at 70% VO2maxfor 1 hour and then at 85% VO2maxuntil exhaustion. Two weeks separated the CHO and PLA tests. The unsupplemented diet in each experimental condition contained 52±6% kilocalories as carbohydrate. This was elevated to 68±6% in the CHO condition. Five of the seven cyclists significantly increased their cycling time to exhaustion in the CHO condition (CHO, 73±9 minutes; PLA, 64±11 minutes). These results indicate that the normal diet of these cyclists contained a suboptimal amount of carbohydrate for optimal performance in the task they set themselves. An immediate post‐training CHO supplementation seemed to improve the subsequent day's performance in most of the present group of competitive cyclists.

ISSN:1057-8315    

DOI:10.1080/15438629409512009

出版商:Taylor&Francis Group    

年代:1994

数据来源: Taylor

摘要:

The aim of this study was to analyze the relationship between two methods of measuring of extensor muscle dynamic force in the inferior limb by means of isokinetic dynamometry and a contact platform system. Twenty‐four members of the junior and senior National Spanish teams for alpine skiing and high jump and track and field athletics participated in the study. The isokinetic dynamometry parameters studied were: peak torque (PT) at five different angular velocities, and total work accomplished in 20 repetitions of maximal intensity effort at an angular velocity of 300°.s‐1(R20). Vertical jump height (SJ) was measured by a contact platform device. The correlation between PT and the vertical jump test was significant p<0.005). The strongest correlation was observed between PT 120°and PT 240°with SJ 20 (r = 0.81; p<0.001). We conclude that both methods may be used satisfactorily to measure the dynamic force of knee extensors muscles. The difference observed between methods may be discussed in terms of the relative utilization of the elastic and reactive components of dynamic force, the participation of other muscular groups in the movement, and other characteristics of ballistic movement.

ISSN:1057-8315    

DOI:10.1080/15438629409512010

出版商:Taylor&Francis Group    

年代:1994

数据来源: Taylor

摘要:

The aim of this study was to evaluate the effect of a daily intake of fluid and salt supplementation in increasing the capacity of endurance‐trained male volunteers for maximum physical exercise after an exposure to 364 days of hypokinesia (decreased number of steps/day) and during a posthypokinetic period of 35 days. The studies were performed after exposure to hypokinesia of 364 days and during the posthypokinetic period of 35 days on longdistance runners who had an average maximal oxygen uptake (VO2max) of 65 ml/kg‐min and ranged from 19 to 24 years of age. Prior to their exposure to hypokinesia, all volunteers completed an average of 14.9 km/day. All volunteers were divided into three equal groups: Group 1 underwent a normal ambulatory life (control subjects), group 2 were placed under continuous restriction of their motor activity being allowed only an average of 2.7 km/ day (hypokinetic subjects), and group 3 also kept continuously to an average of 2.7 km/day but consumed a daily additional amount of 26 ml water/kg body weight and 0.16 g sodium chloride/kg body weight (hyperhydrated subjects). During the experimental period, heart rate, stroke volume, blood pressure, plasma volume, hemoglobin, hematocrit, plasma osmolality, plasma protein, sodium, and potassium concentrations in plasma and water balance were regularly measured. A graded physical exercise test was also performed regularly. During the posthypokinetic period, the capacity of hyperhydrated volunteers to perform maximum physical exercise increased significantly; the group mean heart rate decreased, while stroke volume and blood pressure of the subjects increased. Fluid retention was also much higher in the hyperhydrated hypokinetic than in the hypokinetic‐only volunteers. Plasma volume increased, and hematocrit, hemoglobin, plasma osmolality, plasma protein content, and sodium and potassium concentration in plasma decreased in the hyperhydrated hypokinetic subjects. In the hypokinetic‐only subjects the reverse change was observed. It was concluded that the increased physical capacity of the hyperhydrated subjects for maximum physical exercise after exposure to hypokinesia depends upon the level of body hydration during prolonged restriction of muscular activity.

ISSN:1057-8315    

DOI:10.1080/15438629409512011

出版商:Taylor&Francis Group    

年代:1994

数据来源: Taylor

摘要:

The impact of a nonsteady state, nonrhythmical exercise training program, such as racquetball, on health and fitness variables has not been adequately defined. The purpose of this study was to examine the effect of a 12‐week racquetball training program on maximal oxygen consumption (VO2max). percentage body fat, and blood lipids and lipoproteins. Eight college‐aged male volunteers participated in a 12‐week, three sessions per week, minimum of 30 minutes per session racquetball training program (EG). Eight inactive college‐aged males served as a control group (CG). VO2max, percentage body fat determined from underwater weighing, and blood lipids and lipoproteins were measured before and after the 12‐week program. Heart rate (HR) was monitored in the EG on three separate days while subjects participated in racquetball play. HR was maintained at or above 75% of the subjects’maximum HR after the third minute of play. No differences were found between the EG and CG at the conclusion of the 12‐week training program in VO2max, blood lipoproteins, or percentage body fat. The percentage change in lean body weight after 12 weeks was significantly different between the two groups (EG, 2.0%; CG,‐2.0%). The 12‐week racquetball program did not significantly affect the group mean total cholesterol concentration in the EG, but a difference was found in the group mean total cholesterol between the EG and the CG at the conclusion of the study. Although the HR response to racquetball participation indicated that a racquetball program may be a beneficial, a positive change in several health and fitness parameters may not be routinely expected to be seen after 12 weeks of such training.

ISSN:1057-8315    

DOI:10.1080/15438629409512012

出版商:Taylor&Francis Group    

年代:1994

数据来源: Taylor

ISSN:1057-8315    

DOI:10.1080/15438629409512003

出版商:Taylor&Francis Group    

年代:1994

数据来源: Taylor