Specificity of power improvements through slow and fast isokinetic training

College age males performed maximal two-legged isokinetic knee extensions three times per week for 6 wk at either 60 degrees/s (slow) or 300 degrees/s (fast) or both 60 and 300 degrees/s (mixed). The velocity specific and action specific (two-leg vs. one leg) improvements in peak torque (PT) were compared to a placebo group receiving low-level muscle stimulation. The slow group improved PT significantly (P less than 0.05) more than the placebo group only at its training velocity (60 degrees/s) and more so when the specific two-legged training action was mimicked (+32% with two legs vs. +19% with one leg). The mixed group enhanced PT by 24 and 16% at their respective training velocities of 60 and 300 degrees/s. These improvements were significantly larger than placebo and also significantly larger than the 9% improvement observed at the midvelocity of 180 degrees/s. The training specificity demonstrated by the slow and mixed groups suggest that neural mechanisms contributed to their improvements in power. This is supported by their unchanging muscle morphology. Training solely at 300 degrees/s (fast) however improved PT significantly more than placebo not only at the training velocity (+18%), but also at a slower velocity of 180 degrees/s (+17%). The fast group demonstrated a significant enlargement (+11%) of type II muscle fibers. These data suggest type II fiber hypertrophy to be a plausible mechanism for the nonspecific improvement of the fast group; however, a neurological adaptation that enhances power at and below the training velocity cannot be excluded.

Anthropometric measurements of 3-, 4-, 5-, and 6-year-old girls and boys

This study examined the physical size and subcutaneous body fat of 269 Caucasian boys and girls, ages 3, 4, 5, and 6. In addition to height, weight, and leg length, the measurements included seven diameter, eight circumference, and five skinfold measurements. The means and standard deviations for all anthropometric measurements are presented. When compared by age group, the children were significantly different (p < .01) on all physical size measurements, but not on the skinfold measurements. When the measurements were analyzed to determine significant sex differences, it was evident that, where differences existed, the boys' physical size measurements were larger than the girls', while on the other hand, the girls had a greater amount of subcutaneous body fat than did the boys. The anthropometric data reported in this study did not support the secular trend phenomenon, but substantiated the contention that between three and six years of age, the triceps skinfold measurement declines gradually for boys and remains stable for girls. In summary, it is imperative that anthropometric measurement standards be continually revised and kept current, and that when possible, children be individually evaluated for classification into groups and not classified solely on the basis of age and sex.

Validation of a bench stepping test for cardiorespiratory fitness classification of emergency service personnel

Field tests are used in many occupations to screen and classify personnel for cardiorespiratory fitness. Presumably these tests yield predictive results which correlate well with maximal oxygen uptake (VO2 max), the most widely-accepted criterion of cardiorespiratory fitness. The purpose of this study was to validate one of the most popular field tests, the modified Kasch Pulse Recovery Step Test (KPRST), used by several emergency service agencies in Southern California. One hundred fourteen male state traffic officers from the California Highway Patrol, ranging in age from 24 to 56 years, performed treadmill VO2 max tests to volitional fatigue and the modified KPRST. Heart rates taken during the first and last 10 seconds of the one-minute recovery period for the modified KPRST compared against treadmill VO2 max values yielded correlations of --0.25 and --0.27, respectively, indicating that the modified KPRST is a poor predictor of cardiorespiratory fitness for the population studied. These results suggest that agencies should carefully validate any predictive measure of cardiorespiratory health and performance before adopting that measure for screening purposes and cardiorespiratory classification.

The application of science to sport: physiological profiles of male and female athletes

Detailed physiological profiles have been established for athletes in various sports for both sexes. This paper synthesizes the results from previous studies in the areas of body composition and phsyique; muscle fiber characteristics; strength; and cardiovascular endurance capacity. Similarities and differences between male and female athletes are discussed. While there are rather substantial physiological differences between the average male and the average female, these differences are reduced considerably when comparisons are made between the highly trained male and female athlete who are competing in the same event or sport. Highly trained male and female athletes are similar in lower body strength, when expressed per unit of body weight; cardiovascular endurance capacity; body composition; and muscle fiber type. What once appeared to be dramatic biological differences in physiological function between the sexes, may, in fact, be more related to cultural and social restrictions placed on the female as she attains puberty, i.e. a sedentary lifestyle.

Professional Basketball Players: Athletic Profiles

The physical characteristics of basketball players are closely related to their position on the team, according to this study. The authors believe this type of information would be useful in the selection and training of players.

Anaerobic threshold and maximal aerobic power for three modes of exercise

Alterations in selected respiratory gas exchange parameters have been proposed as sensitive, noninvasive indices of the onset of metabolic acidosis (anaerobic threshold (AT) during incremental exercise. Our purposes were to investigate the validity and feasibility of AT detection using routine laboratory measures of gas exchange, i.e., nonlinear increases in VE and VCO2 and abrupt increases in FEO2. Additionally, we examined the comparability of the AT and VO2 max among three modes of exercise (arm cranking, leg cycling, and treadmill walk-running) with double determinations obtained from 30 college-age, male volunteer subjects. The AT's for arm cranking, leg cycling, and treadmill walk-running occurred at 46.5 +/- 8.9 (means +/- SD), 63.8 +/- 9.0, and 58.6 +/- 5.8% of VO2 max, respectively. No significant difference was found between the leg exercise modes (cycling and walk-running) for the AT while all pairwise arm versus leg comparisons were significantly different. Using nine additional subjects performing leg cycling tests, a significant correlation of r = 0.95 was found between gas exchange AT measurements (expressed as % VO2 max) and venous blood lactate AT measurements (% VO2 max). We conclude that the gas exchange AT is a valid and valuable indirect method for the detection of the development of lactic acidosis during incremental exercise.

Mass spectrometry: application in the exercise sciences

This paper outlines a computerized system for monitoring physiological functions during exercise, using a mass spectrometer for analyzing the concentration of the mixed expired air. Examples are provided illustrating the operation of this system in both research and clinical situations. The most remarkable aspect of the system is its versatility, coupled with its accuracy. While the applications reviewed in this paper are rather narrow, work has been initiated using the mass spectrometer to measure residual lung volumes by the oxygen dilution technique, cardiac output by the CO2 rebreathing technique, and total body density by the helium dilution technique. The application of the mass spectrometer into other areas most certainty will occur in the near future.

Exercise prescription: role of the physiatrist and allied health professional

The prescription of exercise has advanced from an art to a science. The patient must first be examined by a physician to determine if there are contraindications to participating in an exercise program. This examination should include a graded exercise test to volitional fatigue to determine the normality of the electrocardiogram response to exercise and to assess the patient's capacity for exercise. Once the patient has received medical clearance, an exercise program is prescribed. This prescription is based on the individual's exercise capacity and includes a definition of the type, frequency, duration and intensity of exercise. Each of these four factors is discussed in detail and the potential role of the physiatrist, therapist, and allied health professional is defined.

An automated system for assessing metabolic and respiratory function during exercise

This paper provides a brief description of a new, totally automated system for assessing metabolic and respiratory function during exercise. This system was evaluated simultaneously against two established systems, one a computer-based system and the other a semiautomated system, to determine its validity over a wide range of metabolic levels, i.e., less than 2 to greater than 16 mets. A total of 112 males and females, 12-65 yr of age, performed either arm or leg exercises on a bicycle ergometer or treadmill, starting at approximately 2 mets and progressing by approximately 1 met/min to the point of volitional fatigue. Respiratory and metabolic assessments were made each minute during the entire exercise bout. Comparisons across the three systems demonstrated remarkable agreement, particularly when all potential sources of error for each system are considered. Although several statistically significant differences between two of the systems were noted at the lowest work levels, the difference in VO2 between any two systems never exceeded 1.1 ml/kg-min.