Dynamic strength of the quadriceps muscle and sports activity. (1/40)

The study objectives were to examine the dynamic strength of the quadriceps muscle in athletes, and investigate its association with participation in sport. The study comprised 168 active competitive non-pregnant athletes, aged 14-24 years. The dynamic strength of their quadriceps muscle was measured, and they answered a questionnaire about sports activity and occupation. The dynamic strength of the quadriceps muscle was significantly higher in men than in women, and was positively associated with body weight, years of jogging, years of soccer, and weekly hours of basketball. In conclusion, the dynamic strength of the quadriceps muscle seems to be associated with sports activity. The results suggest sport specific adaptation, which may reflect high levels of running and jumping activity.  (+info)

Biomechanics of total hip arthroplasty. (2/40)

The biomechanics of the hip joint provide an understanding of the development, evolution, and treatment of many disabling conditions of this joint. The available methods of biomechanical analysis include in vitro studies, in vivo studies, and theoretical mathematic analyses. The information obtained from these analyses have enabled the design of therapeutic programs to alleviate the symptoms of, and possibly delay the progression of, hip disease. The design of surgical procedures has been based on alterations of the biomechanics of the hip. These procedures have proven useful for treating pathologies such as osteoarthritis, hip dysplasia, and hip fractures. The study of biomechanics and biomaterials are integral to the current success of total hip arthroplasty in achieving pain relief and functional restoration.  (+info)

Effect of stretching duration on active and passive range of motion in the lower extremity. (3/40)

OBJECTIVES: To investigate the effect of different durations of stretching (five or 15 seconds) on active and passive range of motion (ROM) in the lower extremity during a five week flexibility training programme. METHOD: Twenty four university sport club members (19 men, five women), with a mean (SD) age of 20.5 (1.35) years, were randomly assigned to one of three groups (two treatment and one control). The two treatment groups participated in a static active stretching programme three times a week for a five week period, holding each stretch for a duration of either five or 15 seconds. The total amount of time spent in a stretched position was controlled. The five second group performed each stretch nine times and the 15 second group three times resulting in a total stretching time of 45 seconds for both groups for each exercise. The control group did not stretch. Active and passive ROM were determined during left hip flexion, left knee flexion, and left knee extension before and after the training programme using an inclinometer. RESULTS: Two factor within subject analysis of variance indicated no significant difference in ROM before and after the training programme for the control group. However, significant improvements in active and passive ROM (p < 0.05) were shown in both treatment groups after the five week training programme. Two factor analysis of variance with repeated measures and post hoc analysis showed significant differences between the treatment groups and the control group for the improvements observed in active (p < 0.05) and passive (p < 0.05) ROM. The five and 15 second treatment groups did not differ from one another when ROM was assessed passively, but significant differences were apparent for active ROM, with the 15 second group showing significantly greater improvements (p < 0.05) than the five second group. CONCLUSION: These findings suggest that holding stretches for 15 seconds, as opposed to five seconds, may result in greater improvements in active ROM. However, sustaining a stretch may not significantly affect the improvements gained in passive ROM.  (+info)

PET studies of the effects of aerobic exercise on human striatal dopamine release. (4/40)

In vivo microdialysis studies have shown that exercise increases the concentration of dopamine (DA) in the striatum of the rat brain. It has also been shown that PET with [11C]raclopride can be used to assess changes in brain DA induced by drugs and by performance tasks such as playing a video game. The purpose of this study was to evaluate the effects of exercise (treadmill running) on striatal DA release in the human brain. METHODS: Twelve healthy volunteers (5 women, 7 men; mean age, 32 +/- 5 y; age range, 25-40 y) with a history of regular exercise received 2 PET scans with [11C]raclopride on 2 separate days, 1 at baseline and 1 at 5-10 min after running on a treadmill for 30 min. The speed and inclination of the treadmill were increased gradually to reach a maximal speed of 9.7 km/h (6 mph) and a maximal inclination of 10degrees. Data were acquired on a Siemens HR+ scanner in 3-dimensional mode for 60 min. Heart rates and electrocardiograms were monitored. DA D2 receptor availability was measured using the ratio of the distribution volume in the putamen to that in the cerebellum, which is a function of the number of available binding sites/dissociation constant. RESULTS: The subjects ran at an average speed of 8.7 +/- 0.5 km/h (5.4 +/- 0.3 mph) and at an inclination of 3.3degrees +/- 2degrees. The maximum effort of running was maintained for 10-15 min. The heart rates of the subjects were increased by 143% +/- 47%. DA D2 receptor availability in the putamen after treadmill running (4.22 +/- 0.34) was no different from that of baseline (4.17 +/- 0.29; P < 0.6). CONCLUSION: No significant changes in synaptic DA concentration were detected, although the subjects exercised vigorously for 30 min.  (+info)

Jogging and bone mineral density in men: results from NHANES III. (5/40)

OBJECTIVES: This cross-sectional population-based study assessed the association of jogging with femoral bone mineral density (BMD) in men. METHODS: Data are from a nationally representative sample of 4254 men aged 20 to 59 years from the Third National Health and Nutrition Examination Survey (NHANES III). Total femoral BMD was measured by dual energy x-ray absorptiometry. Jogging was self-reported. RESULTS: Jogging (any vs none) was strongly associated with higher BMD in multivariate models (P < .01) for both young and middle-aged men. Men who jogged 9 or more times per month had higher BMD levels than those who jogged only 1 to 8 times per month (P = .01). CONCLUSIONS: Jogging is associated with higher femoral neck BMD in men. Additional large-scale studies that measure all aspects of jogging are warranted.  (+info)

Repetition of an unusual stress fracture in an anorexic man: a case report. (6/40)

Stress fractures of the fibula commonly occur distally in runners, whereas stress fractures of the proximal fibula are uncommon and typically occur in jumpers. Furthermore, it is rare for a stress fracture to be repeated in the same bone. We report a case of a repeated stress fracture of the proximal fibula in a male runner with abnormal gait that primarily involved excessive pronation. Unusual risk factors in this case were anorexia nervosa and use of an inhaled corticosteroid. The patient was treated conservatively, and healing of the fracture was completed at 12 weeks.  (+info)

Construct validity of self-reported historical physical activity. (7/40)

The purpose of this study was to determine the construct-related validity of self-reported historical walking, running, and jogging (WRJ) activity on the basis of data from the Aerobics Center Longitudinal Study (Dallas, Texas). A total of 4,100 men and 963 women underwent at least one medical examination between 1976 and 1985 and completed a follow-up questionnaire in 1986. Levels of glucose, cholesterol, and triglycerides, resting systolic blood pressure, body mass index (weight (kg)/height (m)(2)), and cardiorespiratory fitness were measured at the time of the medical examination. The follow-up questionnaire assessed WRJ and other strenuous activities for each year from 1976 through 1985. Data analysis included Spearman and partial correlations, analysis of variance, analysis of covariance, and t tests. Results indicated significant correlations between recalled WRJ and treadmill times for each year throughout the 10-year period (r = 0.40-0.61). Participants were classified as historically either sufficiently physically active to receive a health benefit or insufficiently active for a health benefit. Engaging in sufficient levels of historical WRJ was associated with higher treadmill times and lower body mass indices for men and women and lower triglyceride levels for men. Self-reported historical WRJ can be assessed with reasonable validity in comparison with measured treadmill performance, with no decay in accuracy of reporting for up to 10 years in the past.  (+info)

Concurrent myocardial and cerebral infarctions after intranasal cocaine use. (8/40)

BACKGROUND AND PURPOSE: Cardiac and cerebrovascular complications associated with cocaine abuse have increasingly been reported, but concurrent development of cocaine-induced cardiac disease and stroke has rarely been reported. CASE DESCRIPTION: A 37-year-old man with a remote history of intravenous heroin and amphetamine use, cardiomyopathy, and recent cocaine use developed chest pain and ventricular tachycardia 30 minutes after intranasal cocaine hydrochloride use and jogging on a cold winter morning. Ventricular tachycardia was converted to atrial fibrillation. He was proven to have a small myocardial infarction. Within 6 hours of cocaine use he suffered a left hemisphere stroke. Cardiac electrophysiologic evaluation revealed inducible ventricular tachycardia. CONCLUSIONS: To our knowledge, this is the first report of concurrent myocardial infarction, life-threatening ventricular arrhythmias, and cerebral infarction temporally related to cocaine use. It is probable that one mechanism by which cocaine use causes stroke is to trigger expression of a known cardiac source of embolism.  (+info)