Kenneth D. Coutts

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

The time course of pulmonary diffusing capacity for carbon monoxide following short duration high intensity exercise

We investigated the time course of changes in post-exercise pulmonary diffusing capacity for carbon monoxide (DLCO), membrane diffusing capacity (DM), and pulmonary capillary blood volume (VC) in highly trained (HT), moderately trained (MT) and untrained (UT) male subjects (n = 8/group). Subjects were assigned to groups based on their aerobic capacity from a preliminary VO2max test (HT > or = 65, MT = 50-60, UT < or = 50 ml x kg(-1) x min(-1)). Resting (BASE) DLCO, DM and VC were obtained, then subjects cycled to fatigue at the highest workrate attained during the preliminary tests. Diffusion measurements were then made at 1, 2, 4, 6 and 24 h. DLCO was depressed at 1 h, lowest at 6 h and approached BASE values at 24 h in all groups. The DLCO change was paralleled by a change in VC. Alterations to VC were similar between groups except at 24 h where MT and HT subjects had returned to BASE while UT did not. DM was significantly lower than BASE at 1, 2, 4, and 6 h, and was similar between groups. The changes in DLCO post-exercise appear to be primarily due to a decrease in VC. Comparable diffusion decrements were observed in all subjects. The results of this study suggest that post-exercise alterations in DLCO, DM and VC are not related to aerobic capacity.

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.

Metabolic responses to prolonged work during treadmill and water immersion running

The primary aim of this study was to compare the physiological responses to prolonged treadmill (TM) and water immersion to the neck (WI) running at threshold intensity. Ten endurance runners performed TM and WI running VO2max tests. Subjects completed submaximal performance tests at ventilatory threshold (Tvent) intensities under TM and WI conditions and responses at 15 and 42 minutes examined. VO2 was lower in WI (p<0.05) at maximal effort and Tvent. The Tvent VO2 intensities interpolated from the TM and WI VO2max tests were performed in both TM (i.e., TM@TM(tvent),TM@WI(tvent), corresponding to 77.6 and 71.3% respectively of TM VO2max) and WI conditions (i.e., WI@TM(tvent), WI@WI(tvent), corresponding to 85.5% and 78.2% respectively of WI VO2max). Each of the dependent variables was analyzed using a 3-way repeated measures ANOVA (2 conditions X 2 exercise intensities X 7 time points during exercise). VO2max values were significantly lower in the WI (52.4(5.1) ml.kg(-1) min(-1)) versus TM (59.7(6.5) ml.kg(-1) min(-1)) condition. VO2 during submaximal tests were similar during the TM and WI conditions. HR and [BLa] responses to exercise at and above WI(tvent) were similar during short-term exercise, but values tended to be lower during prolonged exercise in the WI condition. There were no statistical differences in VE responses in the 2 conditions, however as with HR and [BLa] an upward trend was noted with TM exercise over the 42 minute duration of the tests. RPE at WI(tvent) was similar for TM and WI exercise sessions, however, RPE at TM(tvent) was higher during WI compared to TM running. Cardiovascular drift was observed during prolonged TM but not WI running. Results suggest differences in metabolic responses to prolonged submaximal exercise in WI, however it can be used effectively for cross training.

Effect of body position on measurements of diffusion capacity after exercise

Background—Pulmonary diffusing capacity for carbon monoxide (Dlco), alveolar capillary membrane diffusing capacity (Dm), and pulmonary capillary blood volume (Vc) are all significantly reduced after exercise. Objective—To investigate whether measurement position affects this impaired gas transfer. Methods—Before and one, two, and four hours after incremental cycle ergometer exercise to fatigue, single breath Dlco, Dm, and Vc measurements were obtained in 10 healthy men in a randomly assigned supine and upright seated position. Results—After exercise, Dlco, Dm, and Vc were significantly depressed compared with baseline in both positions. The supine position produced significantly higher values over time for Dlco (5.22 (0.13) v 4.66 (0.15) ml/min/mm Hg/l, p = 0.022) and Dm (6.78 (0.19) v 6.03 (0.19) ml/min/mm Hg/l, p = 0.016), but there was no significant position effect for Vc. There was a similar pattern of change over time for Dlco, Dm, and Vc in the two positions. Conclusions—The change in Dlco after exercise appears to be primarily due to a decrease in Vc. Although the mechanism for the reduction in Vc cannot be determined from these data, passive relocation of blood to the periphery as the result of gravity can be discounted, suggesting that active vasoconstriction of the pulmonary vasculature and/or peripheral vasodilatation is occurring after exercise.

The relationship between test protocol and the development of exercise-induced hypoxemia (EIH) in highly trained athletes.

AbstractHealthy male endurance-trained cyclists [n = 11, age = 27.3 (3.9) years; mass = 73.0 (9.3) kg; height = 180.5 (6.9) cm; maximal oxygen consumption (

Effects of two entrainment patterns on performance of female novice rowers

\dot VO_{2max}

The relationship of the heart rate deflection point to the ventilatory threshold in trained cyclists.

= 71.1 (5.8) ml · kg−1 · min−1, mean ± (SD)] were recruited to assess the relationship between test protocol and the development of desaturation of arterial hemoglobin with oxygen, during incremental exercise tests to maximal aerobic capacity