Frank I. Katch

Effects of physical training on ventilatory equivalent and respiratory exchange ratio during weight supported, steady-state exercise.

Thirty-three college men participated in a 9-week endurance training program. An equal number of subjects served as controls. Pre- and post-test metabolic measurements were made during 10 min of submaximal exercise (1080 kpm/min at 60 rpm) and 15 min of recovery. Measurements included oxygen consumption, CO2 production, ventilatory equivalent (VE/VO2 ratio) and respiratory exchange ratio (R). A three factor design variance analysis was used to analyze the effects of training on min-by-min exercise and recoveryVE/VO2 ratio andR. For the experimental group training resulted in a significant improvement in ventilatory efficiency during exercise, as well as a significant decrease inR. During recovery,VE/VO2 andR decreased significantly for both groups although the magnitude of change was greater for the group that trained. Apparently, there was a significant habituation effect due to test procedures for the control group. The results are discussed in terms of lactate production and substrate utilization during exercise.

Reliability, Individual Differences, and Intravariation of Endurance Performance on the Bicycle Ergometer.

Abstract A procedure is described for measuring endurance performance on the bicycle ergometer where all individuals begin work at the same pace initially and continue for the same duration of time. Individuals with 100% endurance showed no drop-off in work rate from the initial pace, while those lower in endurance showed varying amounts of drop-off. Reliability, individual differences, and intravariation of endurance performance were determined for 34 subjects who pedalled a Monark bicycle ergometer at an initial work rate of 1,512 kgm/min for 10 min. on two occasions. Because the initial rate of work was so heavy there was an average 17.5% drop-off in work rate at the end of the test. Test-retest reliability for the endurance scores (defined as cumulated work performed) was r = .87. Within each test, individual differences increased progressively over the 10 min. to 420%, while intravariation increased 55%. In the test-retest situation, reliability increased 45%, individual differences increased 30-fold...

Pre- and post-test changes in the factors that influence computed body density changes.

Abstract Individual changes in the body density of 62 young men who participated in a 10-week physical conditioning program were found to be more closely related to changes in residual lung volume (r = .49), than to changes in body weight (r = .31) or underwater weight (r = .26). Thus, the computed changes in body density for individual subjects were related as much to individual changes in residual lung volume as to changes in underwater weight or body weight. There was a mean decrease in body weight (1.3%) and residual lung volume (4.5%), while underwater weight increased 1.2% and the resulting body density increased .0008 density units. It was concluded that if an assumed constant value of residual volume is used to compute density, then observed changes in body density for an individual subject due to an experimental treatment such as physical conditioning may be masked by large changes in residual lung volume.

Bicycle Ergometer Endurance in Women Related to Maximal Leg Force, Leg Volume, and Body Composition

Abstract Endurance in 29 college women was measured on a bicycle ergometer. Subjects pedaled against a constant frictional resistance of 2.5 kg for 6 min at an initial rate of 60 rpm (900 kg-m). Decrement in performance from minute 1 to 6 averaged 28.1%. Reliability of test-retest endurance was high (r = > .90 after minute 1). Maximal leg force (MLF) measured during cycling at 60 rpm on an isokinetic ergometer correlated r = .73 and .74 with performance at minutes 2 and 3, but r = .51 to .57 for the other minutes. Removing heterogeneity in body weight and lean body weight from the MLF versus performance correlations by use of partial correlations reduced the correlations by 7.5% and 18.3%, respectively. The correlations were significant but low (p < .05) between endurance, leg volume, and body composition. Prediction of cumulative endurance of 6-min duration was satisfactory with a shorter 2- to 4-min performance, since the correlation in predicting the 6-min results were high after minute 2 (r = .76), mi...

Prediction of Oxygen Intake from Ventilation, and Oxygen Intake and Work Capacity from Heart Rate During Heavy Exercise.

Abstract Minute-by-minute O2 intake, ventilation volume, and heart rate were correlated during 12 min. of heavy, fatiguing exercise on the bicycle ergometer (N = 50). The 12 min-by-min mean [Vdot]E values correlated r = .97 with the corresponding mean [Vdot]O2 scores during exercise and r = .98 during 10 min. of recovery. Correlations across individuals for [Vdot]O2 and [Vdot]E were also relatively high during the last 3 min. of exercise and during 10 min. of recovery. This means that [Vdot]E could be used to predict [Vdot]O2 very effectively. On the other hand, the min-by-min correlations between individual heart rates and O2 intakes were low (r = .06 to −.29) and nonsignificant. When the changes from resting to exercise in heart rate (Δ HR) and O2 intake (Δ [Vdot]O2) were grouped by 4-min. intervals, the correlations were somewhat higher (r = .10 for the period 0-3, .38 for 3–6, .72 for 6–9 and .47 to 9–12). However, these correlations were still too low to be of much predictive value. Oxygen pulse ([Vd...