SLOW COMPONENT OF AEROBICS ONLY STIMULATED BY HEAVY ARDUOUS SWIMMING
Filho, P., Müller, D., Reis, J., Alves, F., & Denadai, B. S. (2010). Oxygen uptake kinetics around the respiratory compensation point in swimming. A paper presented at the XIth International Symposium for Biomechanics and Medicine in Swimming, Oslo, June 16–19, 2010.
"The upper boundary of the heavy domain is the highest intensity in which oxygen uptake (VO2) and blood lactate concentration can be maintained at an elevated but steady level." This study described the VO2 kinetics throughout the heavy and severe domains during front crawl swimming, considering the respiratory compensation point as the transition parameter. Male swimmers (N = 9) performed the following tests (using a portable breath-by-breath system connected to a snorkel and valve): 1) incremental swimming with 300 m stages ranging from 85 to 100% of maximal swimming velocity at 400 m pace (to determine the velocity at the ventilatory threshold, respiratory compensation point, and VO2max (vVO2max); and 2) a square-wave test performed twice, from rest to one of two velocities set at 2.5% below and above the respiratory compensation point (to describe VO2 kinetics using a bi-exponential model).
The trial below the respiratory compensation point was performed at a velocity of ~36.8% of the difference between the velocity at ventilatory threshold and VO2max, with a slow component eliciting only a sub-maximal rate (~91.6 % of VO2max). The trial above the respiratory compensation point produced the maximum slow component (~104 % of VO2max).
The main aerobic responses observed were: a) patterns in the time constant for the primary and slow components remained unchanged; b) time delay was significantly shorter during exercising at the severe domain only for the primary component; and c) the slow component remained unchanged between the heavy and severe domains, but led to the attainment of VO2max when swimming above the respiratory compensation point.
Implication. The VO2 kinetics around the respiratory compensation point are associated with pulmonary VO2 responses that are elicited with heavy and severe swimming tasks (i.e., the highest level of steady-state aerobic kinetics and lactate accumulation). The slow component of the aerobic kinetics is only elicited by long arduous swimming tasks, most of which have little relevance to races conducted in swimming pools.
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