Ernest D. Michael

Body composition of high school wrestlers according to age and wrestling weight category

ABSTRACTThe body composition of 94 high school wrestlers, 15 to 18 years of age and 98 to 233 lbs., was measured using skinfold and girth measurements. Three regression formulae were used to predict body density and percent body fat, and comparisons were made by age and wrestling weight category. Th

Physiological changes of teenage girls during five months of detraining.

ABSTRACTTen girls from a high school track team were tested during the first, third, fifth, seventh and twenty-third week post-training using a 3 minute step test and a treadmill ran. The heart rate response to the light work of the step test and the light 2 and 4% grade treadmill runs increased sig

Effect of marihuana on cardiorespiratory responses to submaximal exercise

Six male chronic marihuana (MH) users exercised on a bicycle ergometer for 15 min at ∼ 50% Vo2max under 3 conditions: (1) not smoking (control), (2) after smoking MH containing 7.5 mg (−) delta‐9‐tetrahydrocannabinol, and (3) after smoking placebo marihuana (PL). The MH was administered double‐blind in a counterbalanced repeated‐measures design. Heart rates (HRs), arterial blood pressures (BPs), pulmonary ventilation (VE), and oxygen uptake (Vo2) were measured during exercise and 15 min recovery. PL had no effect on any of the physiologic variables. Smoking MH had no effect on systolic blood pressure (SBP), diastolic blood pressure (DBP), VE, or Vo2. but did induce a marked increase in heart rate which persisted throughout exercise and recovery periods, averaging 34% higher than control values at rest, 18% higher during exercise, and up to 50% higher during recovery. MH smoking increased the product of HR × SBP in all circumstances.

Effect of Warm-up on Softball Throw for Distance

Abstract The purpose of this study was to investigate the effects of related and unrelated warm-ups on the distance a 12-inch softball could be thrown. The subjects, 77 college men, threw three softballs for distance with no preliminary warm-up, with a preliminary five-minute related throwing warm-up and with a preliminary five-minute non-related general warm-up. The results showed that both types of warm-ups resulted in significantly longer throws. There was no significant difference between the various types of warm-up and no significant warm-up effect was demonstrated between trials 1 and 3 on a particular day of testing. The time spent and the strenuousness of the warm-up appeared to be factors involved in improving the distance the balls were thrown.

Performance as Affected by Incentive and Preliminary Warm-Up

Abstract Forty-six male students, ages 18 to 22 years, were given a softball throw for distance without warming up and with a 5-minute related warm-up preceding throwing. The subjects were divided into two groups with the sequence of warm-up and no warm-up alternated on different days in order to reduce the possibility of practice effect, learning, or other unforeseen factors. Three throws for maximum distance were allowed for each testing period. In an attempt to rule out the possible psychological effects of not making a maximum throw without preliminary warm-up, the subject was given a monetary reward for each throw greater than his established average. A significant difference at the 1 percent level of probability was found between trials 1 and 3 when no warm-up preceded throwing. No significant difference was found between trials when throwing was preceded by a warm-up. Despite the significant increase in distance between trials 1 and 3 when no warm-up preceded throwing, subjects threw on the average...

Physiological Variables Related to the Selection of Work Effort on a Treadmill and Bicycle.

Abstract Ten female subjects were asked to run on a treadmill at a speed selected previously to tire them in 15 minutes. They later were asked to try to repeat the same work effort on a bicycle. Heart rate increased 60% from either a slow walking base level or a nonloaded bicycle ride at 60 rpm, and RQ rose to .90 when the subjects felt work effort on a treadmill and bicycle were equivalent. The absolute value of oxygen uptake, ventilation, and heart rate did not indicate to the subject that the physiological strain was similar, since all these measurements were lower on the bicycle during the selected work effort. The oxygen debt was not related to physiological strain, since the treadmill O2 debt was double that of the bicycle exercise, though the subjects felt they were exercising at the same work level.

Densitometric Validation of Six Skinfold Formulas to Predict Body Density and Percent Body Fat of 17-Year-Old Boys.

Abstract In order to evaluate the variable and constant error of skinfold prediction equations for estimating body density and body fat, 18 skinfold and girth measures were determined in 40 young males. The subjects were also weighed underwater to determine the criterion body density directly. The constant errors of prediction were very high, ranging from −10 to 122 percent. Validity coefficients ranged from r = .795 to .863; thus the predictive error of individual scores was 25 to 37 percent. In view of the large constant errors, the utility of these formulas for clinical application in estimating leanness and fatness is questionable. The relative ordering of individuals on the leanness-fatness scale can be accomplished more successfully, but the validity is moderate rather than high.

Periodic Changes in the Circulation during Athletic Training as Reflected by a Step Test

Abstract A one-minute step test at 36 steps per minute on a 17-in. bench was given to 17 varsity basketball players each three weeks during 16 weeks of training and after 10 and 20 weeks of detraining. The results indicated that the recovery pulse rate made significant changes in three weeks (.05 level) and highly significant changes in six weeks (.01 level). This level of conditioning was maintained throughout the season to reach a maximum change in 16 weeks. In 10 weeks of detraining significant reversal changes had occurred so that conditioning was not maintained when the season ended.

Effects of Speed and Grade Change on the Ability to Reproduce a Standard Work Effort.

The purpose of the study was to investigate the ability of subjects to reproduce the “feeling” of a standard treadmill exercise task under conditions of changing speeds and grades. Subjects (12 males, 9 females) first performed a standard treadmill run (6.0 mph, 0% slope) and then a run in an experimental condition of either a variable-grade, fixed-speed (3.5 mph) or a variable-speed, fixed-grade (5%). Under the experimental conditions subjects attempted to adjust the speed or grade so as to reproduce the work effort they had exerted on the standard exercise task. Results showed that the O2, CO2, E and HR under the fixed grade-variable speed condition were significantly greater than under the other conditions. While running up an incline at a speed chosen by themselves, subjects apparently will perceive the work effort to be the same as running on the level, when in fact it is costing them more energy.

Circulatory Adjustments to Training for Apneic Diving

Abstract Twelve subjects classified into three groups, viz., experimental, control, and currently active skin divers, were studied throughout a 24-week period. The experimental group participated in an underwater swimming training program, three days a week, for four weeks. The testing procedures for all subjects each week consisted of the following: a 1-min. step test, brachial pulse wave test, a V4 ECG test, and blood pressure measurements. Radial pulse recordings were taken on those individuals who showed marked changes on the above tests when they held their breath. In no phase of the study were any of the subjects physiological responses to breath holding, as measured by the tests used, changed significantly. The changes which occurred with subjects in this study when they held their breath are discussed in relation to the findings from recent studies.