No abstract

The ventilatory (anaerobic) threshold for short-term exercise was defined as the work rate or O2 uptake (VO2) immediately below the work rate at which ventilation increased disproportionately relative to work rate or VO2, and the ventilatory threshold for long-term exercise as the work rate or VO2 immediately below the work rate at which ventilation continued to increase with time rather than attain a steady state. The purpose of the present study was to investigate how both thresholds relate to each other and how they relate to other measures of physical performance capacity. The subjects were eight healthy males, 20-53 yr of age. Maximal performance capacity was estimated by measurements of maximal O2 uptake (VO2 max) and by endurance performance during a 12-min distance run. A high interrelationship was found between the two thresholds (r = 0.84), and each threshold expressed in VO2 (ml X min-1 X kg-1) correlated highly with VO2 max (r = 0.87 and r = 0.75, for short-term and long-term exercise, respectively). When the two thresholds were expressed as a percentage of VO2 max, neither threshold showed a significant relationship with VO2 max. Endurance performance was significantly correlated with both the ventilatory threshold for short-term and long-term exercise (r = 0.73 and 0.82, respectively). A stepwise multiple regression analysis indicated that the distance run in 12 min was best predicted by VO2 max (R2 = 0.66) or the ventilatory threshold for long-term exercise (R2 = 0.63). It is concluded that the ventilatory threshold for long-term exercise is a more specific measure to explain running performance than is the threshold during graded exercise.

The ventilatory (anaerobic) threshold during short-term exercise has been defined as the O2 uptake (VO2) immediately below the VO2 at which pulmonary ventilation (VE) increases disproportionally relative to VO2 and the ventilatory threshold for long-term exercise as the VO2 immediately below the VO2 at which the VE continues to increase with time rather than attain a steady state. Maximal endurance performance was determined by measurement of the maximal endurance time during treadmill runs at 90%, and 70% of the previously determined VO2 max. The purpose of the present study was to investigate how maximal endurance performance was related to both ventilatory thresholds and to VO2max, and to select which variable best explained maximal endurance performance. The subjects were 11 healthy males. Maximal endurance performance was significantly correlated with the ventilatory threshold for long-term exercise and VO2max. A stepwise multiple regression analysis indicated that maximal endurance performance was best predicted by the ventilatory threshold for long-term exercise. Combination of variables could not improve the prediction. It is concluded that the ventilatory threshold for long-term exercise better explains maximal endurance performance than VO2max or the ventilatory threshold during short-term exercise.

At the Institut pour la Recherche Scientifique en Afrique Centrale (I.R.S.A.C.), Station of Lwiro on Lake Kivu, Republic of Zaire, anthropometric and spirometric measurements were made on 25 male members of a pygmy clan, living the traditional hunter-gatherer's life on the slopes of the Mitumba mountain range. The response of 15 men to graded exercise was tested on a bicycle ergometer. The morphology of the Kivu Twa was in agreement with that described for pygmies in the same general area. Blood pressure was extremely low, 99/64 (SD +/- 12/11) mm Hg, and was not affected by age. Lung volumes were small compared to those of Europeans, and fitted well the standards for the 'Bantu' in South Africa. The vital capacity of adult men was 3.183 (SD +/- 0.151)l and the one-second forced expiratory volume 2.558 (SD +/- 0.11)l. Their cardiovascular response to increasing physical work-loads was similar to that of other population samples in Central Africa and quite close to those of the Equator Twa. The maximum aerobic power, calculated indirectly, was small, 1.957 (SD +/- 0.158)l/min, but when expressed per kg body weight was 42.5 (SD +/- 5.2) ml min-1 kg-1, comparable to that of many other populations.