Michael G. Maksud

A comparison of plasma cholesterol, triglycerides. and high density lipoprotein-cholesterol in speed skaters, weightlifters and non-athletes

SummaryVenous plasma cholesterol, triglycerides and high-density lipoprotein cholesterol (HDL-C) were measured after a 12–16 h overnight fast in three groups of men with different physical training histories. The groups consisted of 11 untrained men (aged 19–25 years), 11 well-trained weightlifters (20–32 years), who had not trained aerobically for at least 6 months, and 11 candidates for an Olympic speed skating team (17–27 years), whose training was both endurance (aerobic) and anaerobic. Mean maximal oxygen uptakes for the groups were 47.7, 45.7, and 62.3 ml·kg−1·min−1 respectively. Groups were similar with respect to diet, smoking and alcohol consumption, but the nonathletes were fatter, the weightlifters older and the speed skaters lighter, than the others. There were no significant differences in total cholesterol or triglycerides between the groups. Mean HDL-C was similar in the non-athletes and weightlifters [about 47±7 (SD) mg·dl−1], but was significantly higher (53.7±10.2 mg·dl−1, p<0.05) in the speed skaters. It was not correlated significantly with maximal oxygen uptake or relative fat in any group or when all data were combined. The total cholesterol/HDL-C ratio was significantly higher in the weightlifters. The HDL-C values are compared with previously reported values for non-athletes and athletes, and it is concluded that extensive weight-training, in contrast to endurance training, does not increase venous plasma HDL-C. Further work is required to elucidate the biochemical basis of these observations.

Alterations in pulmonary function consequent to competitive marathon running.

This study was designed to investigate the mechanisms underlying the significant reductions in vital capacity after marathon racing originally reported over 50 years ago. Spirometric, maximum expiratory flow-volume (MEFV), DLCO and residual volume (RV) measurements were made on 13 runners (11 males and 2 females) 1--2 weeks prior to the marathon, immediately after finishing the race, and again the next day. An average 0.48 L (8.6%) reduction in post-race forced vital capacity (FVC) was accompanied by an equivalent increase in RV. Thus, total lung capacity did not change, and the reduction in FVC was a result of an expiratory rather than an inspiratory limitation. Post-race FEV1 and FEF200-1200 remained unchanged while FEV1-2, FEF1 and FEF2 were reduced 19.7, 26.7 and 23.3%, respectively. Mean DLCO was unchanged. Pulmonary function on the following day was similar to that observed on the control day. These data indicated that after the race, expiratory flow was unaffected at high lung volumes, but was decreased at low lung volumes (within the effort-independent portion of the MEFV curve). The results are compatible with small airway closure occurring at an increased lung volume, which would result in a decreased FVC and an increased RV.

Comparison of a continuous and discontinuous graded treadmill test for maximal oxygen uptake.

ABSTRACTThe purpose of the study was to compare a single session continuous-graded treadmill protocol for determining maxVo2 in healthy male subjects with the multi-session discontinuous-graded treadmill procedure described by Taylor and his co-workers. Twenty young adults served as subjects for the

Application of the Cooper Twelve-minute Run-walk Test to Young Males.

Abstract The study was designed to establish norms for the Cooper 12-minute run-walk test applicable to young males. Eighty boys, 11 through 14 years of age, served as subjects. The mean distance covered by the 11- and 12-year-olds during the 12-minute run-walk was 2,308 yards. The mean distance covered by the 13- and 14-year-olds was 2,507 yards. The difference between the two groups was statistically significant (P<.01). The test-retest reliability coefficient for the test on a subsample was .92. Maximal aerobic capacity was also measured with a subsample of 17 subjects to determine the relationship between aerobic capacity and run-walk performance. The correlation coefficient between aerobic capacity and run-walk performance was .65. While the correlation was statistically significant (P<.01), caution is advised in attempting to predict aerobic capacity from run-walk performance with young urban subjects.

Energy Expenditure and [Vdot]O2 Max of Female Athletes during Treadmill Exercise

Abstract Several physiological responses, including oxygen uptake, of a group of female athletes (N = 26) were measured during various levels of treadmill exercise. Their aerobic power was also measured and correlated with performance on the Cooper 12-min-run test. The energy requirement during treadmill exercise, expressed as [Vdot]O2/kg · min-1, was very similar to values reported for males. The mean aerobic power was 41 ml/kg · min-1. A statistically significant correlation (r = .70) was found between aerobic power and performance on the Cooper 12-min-run test. This was consistent with previous studies.

Physiological responses to exercise in chronic cigarette and marijuana users

SummarySeveral physiologic responses to graded exercise were determined in four groups of young adult blue-collar workers identified as users of (1) marijuana, (2) cigarettes, (3) both marijuana and cigarettes, or (4) neither substance. Using covariate analysis of variance to control for race, age, height, and weight, the groups did not differ in estimated percent fat, lean body mass, hematocrit levels, or blood hemoglobin values. Heart rate and oxygen consumption responses also were similar at all levels of exercise. The mean minute ventilation and perceived exertion were found to be higher in cigarette smokers than non-smokers of cigarettes but aerobic power and the physical work capacity did not differ. The differences in pulmonary function observed suggest the need for further study on older populations of chronic cigarette and marijuana users.

Time course of lung volume changes during prolonged treadmill exercise

It has been known since the 1920s that runners completing marathon races have reduced forced vital capacity (FVC) values. To investigate the time course of these lung volume alterations, we measured FVC and residual volume (RV) in 11 runners before, after, and at 30-min intervals during a 2.5-h treadmill run at just under their marathon pace (70% VO2max). Mean distance run was 21.5 +/- 1.5 (SD) miles in the 2.5-h period. During the first 60 min, both RV and total lung capacity (TLC) decreased by 110 ml, however, this change was not significant (P greater than 0.05). A high correlation (r = 0.93) was observed between delta RV and delta TLC during the first 5 min, while FVC remained unchanged. From 60-90 min, all lung volumes remained constant. From 90-150 min, lung volumes changed in a direction similar to that observed after a marathon, i.e., FVC decreased significantly (5.51 to 5.37 liter between 90 and 150 min, P less than 0.05), TLC remained unchanged (7.41 vs 7.42 liter, P greater than 0.05), and RV showed a nonsignificant increase from 1.90 to 2.05 liter (P greater than 0.05). The data are consistent with multiple mechanisms playing a role in pulmonary function changes during prolonged exercise. The smaller mean decrease in FVC observed in this study, as compared to that found during a marathon, suggested that the marathon imposes a greater demand on the lungs than did treadmill exercise of the duration and relative intensity used in this study.

Oxygen uptake, ventilation, and heart rate. Study in Negro children during strenuous exercise.

Various physiological responses to strenuous exercise were measured in a group of 100 clinically healthy Negro children from the “inner core” area of Milwaukee. The subjects included 47 boys and 53 girls with an age range of 9 to 11 years. The height, weight, and body surface area of the subjects in this study were consistently lower than data reported in the literature for similar age groups. The work capacity, employing the criteria of “maximal” oxygen uptake, was also lower than most data reported on similar age groups. The data suggest that the physical work capacity of “disadvantaged” children is reduced, perhaps reflecting a poor nutritional status.