Summary
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V[O.sub.2] off transient kinetics in extreme intensity swimming.
Introduction
Oxygen uptake (V[O.sub.2]) kinetics has been analyzed through mathematical modeling of the constant-load exercise onset and offset V[O.sub.2] response. This response profile appears to be of an exponential nature, which could indicate first or second order kinetics operations (DiMenna and Jones, 2009). This analysis has shown that V[O.sub.2] exponentially increases at the onset of moderate exercise with constant power output (on-fast component), reaches a steady state, and rapidly decreases at the offset of moderate exercise (off-fast component) (Kilding et al., 2006; Ozyener et al., 2001; Paterson and Whipp, 1991; Scheuermann et al., 2001). First-order kinetics mandates on/off symmetry, which means that the change in V[O.sub.2] occurring when the contractile activity is ceased must be a mirror image of that which occurred when it was commenced (Rossiter et al., 2005). In the heavy intensity exercise, i.e., at intensities greater than the anaerobic threshold but below the maximal V[O.sub.2], an delayed increase (on-slow component) after the on-fast component is presented (Barstow and Mole, 1991; Barstow et al., 1996; Ozyener et al., 2001; Paterson and Whipp, 1991; Scheuermann et al., 2001), but at the offset only an off-fast component is developed (Ozyener et al., 2001; Scheuermann et al., 2001). At the severe exercise intensity, which is significantly above the anaerobic threshold, and neither V[O.sub.2] nor blood lactate levels can be stabilized (Poole et al., 1988), the on-transient V[O.sub.2] kinetics is reverted to a single-exponential profile (Ozyener et al., 2001), while the off-transient kinetics is retained for a two-component form (Dupond et al., 2010; Ozyener et al., 2001). At the highest intensity--ext...See the full content of this document
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