O2 Max Research Articles

Cardiorespiratory responses of young overweight women to ergometry following modest weight reduction.

In a 15-week weight reduction study, 19 overweight young (aged 18 to 22) women adhered to volitional dieting (group D), exercise (group E), or volitional dieting plus exercise (group DE). Body weight and fat losses were modest yet significant but were not different among groups. Bicycle and treadmill progressive work tests were administered before and after weight reduction. On the bicycle, maximum oxygen consumption ([vdot]o2 max), heart rate (HR), and work rate (WR) were unchanged in group D. Groups E and DE increased [vdot]o2 max and WR. During treadmill exercise, [vdot]o2 max for group D remained unchanged, whereas groups E and DE had higher [vdot]o2 max and WR; max HR was lower in groups D and E. Conditioning increased [vdot]o2 max and reduced HR at submaximal work loads, particularly during treadmill work.

Longitudinal variations in maximal oxygen intake with age and activity.

Longitudinal variations in maximal oxygen intake with age and activity.

Estimated cardiorespiratory response during marathon running.

Cardiorespiratory responses during marathon running (42.2 km) were estimated on nine nationally ranked marathon athletes. Oxygen consumption ([vdot]o2), ventilation ([vdot]E), and heart rate (HR) were predicted from competitive data (average speed) using individual regression equations derived from steady-state values measured in the laboratory. From these predictions, ventilation equivalent ([vdot]E/[vdot]o2) and oxygen pulse ([vdot]o2/HR) were calculated. Stroke volume (q), cardiac output ([Qdot]), and the arteriovenous oxygen difference (a-⫨O2 diff) were estimated as follows: q = q max = Vo2 max/[Hgb] × O2 capacity of Hgb × (SaO2 – S⫨O2) max × HR max; [Qdot] = q × HR; and a-⫨O2 diff = [vdot]o2/[Qdot]. The [vdot]o2 max, HR max, and [Hgb] were measured in the laboratory; (SaO2 - S⫨O2) max was as- sumed to be O.7. These steady-state estimates were evaluated with respect to the effects of race duration and environmental factors. It was concluded that q, [Qdot], and particularly HR are heavily stressed duri...

Diet, muscle glycogen, and endurance performance.

Diet, muscle glycogen, and endurance performance.

Assessment of the exercise capacity of young men.

The exercise capacity of groups of military personnel (281 men in all) has been assessed from estimates of maximal oxygen intake ([Vacute]o2, max) and the Harvard Step Test. [Vacute]o2 max was derived by extrapolation from heart rates and oxygen intakes during a submaximal stop test Initial studies determined the oxygen intake — work rate relationship for this step test and the resulting straight line was used for the subsequent prediction of oxygen intake. Tests repeated within one week showed slightly improved [Vacute]o2 max values, but reproducibility was good (test-retest r = 0.96 for 72 men). Five groups of contrasting fitness, that is well trained and comparatively untrained men, were found to have different [Vacute]o2 max values. Five groups underwent regimes of training, three of these groups showed marked increments of [Vacute]o2, max but two groups who undertook longer training of a more specialized nature showed smaller increments. The results of the Harvard Step Test were of a similar pattern to the [Vacute]o2 max results, but reproducibility was poorer (test-retest r =0.80 for 12 men, and only 0.50 for one group of 37 men).

The aerobic and anaerobic components of work during submaximal exercise on a bicycle ergometer.

Abstract Inter-subject variability of oxygen intake ([Vdot]O2)n relation to the anaerobic component of work has been investigated intensely on two healthy subjects and extensively on two groups of young and older men during work on an upright, stationary bicycle ergometer. Significant differences (p<0·001) in [Vdot]O2 were shown to exist between the two groups of subjects and the healthy men at the higher work-loads which could not be eliminated entirely by correction for body weight. The residual variation of [Vdot]O2 on work-load was shown to be a consequence of the variation of anaerobic component of exercise. During work on a bicycle ergometer at exercise above about 50% [Vdot] O2 max this should be taken into account if a valid assessment of energy expenditure is to be made.

Effects of physical training on exercise blood flow and enzymatic activity in skeletal muscle.

Six weeks' physical training of seven healthy subjects was followed by a mean decrease of exercise muscle blood flow (ml./100 g/min) from 32·7 to 22·6 and an increase of succinic dehydrogenase activity ( V O2 μl./g/min) from 33·0 to 47·4 in vastus lateralis muscle. Estimated maximal aerobic power ( V O2 max.) increased by 30%. These results support the hypothesis based on previous evidences that the main circulatory changes in physical training occur in the circulation of the skeletal muscle.

Oxygen uptake during maximal treadmill and bicycle exercise.

Oxygen uptake during maximal treadmill and bicycle exercise.

Limitations to the prediction of maximum oxygen intake from cardiac frequency measurements.

Limitations to the prediction of maximum oxygen intake from cardiac frequency measurements.