Oxygen uptake kinetics during severe intensity running and cycling

Abstract

The purpose of this study was to investigate the effect of exercise mode on the characteristics of the oxygen uptake (VO(2)) ()response to exercise within the severe intensity domain. Twelve participants each performed a treadmill running test and a cycle ergometer test to fatigue at intensities selected to elicit a mode-specific VO(2)max and to cause fatigue in ~5 min. The tests were at 234 (30) m.min(-1) and 251 (59) W, and times to fatigue were 297 (15) s and 298 (14) s, respectively. The overall rapidity of the VO(2)response was influenced by exercise mode [VO(2)max was achieved after 115 (20) s in running versus 207 (36) s in cycling; p<0.01]. VO(2) responses were fit to a three-phase exponential model. The time constant of the primary phase was faster in treadmill tests than in cycle ergometer tests [14 (6) s versus 25 (4) s; p<0.01], and the amplitude of the primary phase was greater in running than in cycling when it was expressed in absolute terms [2327 (393) ml.min(-1) versus 2036 (301) ml.min(-1); p=0.02] but not when it was expressed as a percentage of the total increase in VO(2) [86 (6)% versus 82 (6)%; p=0.09]. When quantified as the difference between the end-exercise VO(2) and the VO(2) at 2 min, the amplitude of the slow component was ~40% smaller in running [177 (92) ml.min(-1) versus 299 (153) ml min(-1); p=0.03]. It is concluded that exercise modality affects the characteristics of the VO(2) response at equivalent intensities in the severe domain.

Time to exhaustion at maximal lactate steady state is similar for cycling and running in moderately trained subjects

“…Differences in blood lactate concentration at MLSS for different exercise modes have previously been reported by Beneke and von Duvillard (1996). An explanation for different blood lactate concentration between exercise modes, despite comparable workloads, is the different metabolic cost of exercise modes (Carter et al 2000, Hill et al 2003. However, when blood lactate concentration at MLSS is calculated as % of peak blood lactate concentration, the difference disappears.…”

Differential Effects of B and T Lymphocyte Attenuator and Programmed Death-1 on Acceptance of Partially versus Fully MHC-Mismatched Cardiac Allografts

“…Exercise tests were additionally categorised according to whole-body or isolated limb exercise (exercise mode), since differences in exercise mode influence energy substrate usage 33 and oxygen uptake kinetics. 34 Differences in whole-body and isolated muscle recruitment have also been suggested to contribute to the efficacy of β-alanine due to differences in whole body versus local muscle acidosis. 15 Exercise tests were similarly categorised according to whether they employed an intermittent or continuous exercise protocol (intermittent).…”

Influence of test duration on oxygen uptake attained during treadmill running

“…response may be considerably quicker than that which has been reported in previous studies of treadmill running (Carter et al, 2000;Carter et al, 2002;Hill et al, 2003). For the mono-exponential response described, the time constant averaged 10.7 s, emerging after an average delay of 11.2 s, suggesting a complete response in ~54 s (i.e., delay + [4 x time constant]).…”

“…Across all exercise intensity domains, studies have typically examined responses to cycling exercise in subjects who are not well trained (e.g., (Bearden et al, 2004;Endo et al, 2004;Gerbino et al, 1996;Hill et al, 2003;Scheuermann & Barstow, 2003;Whipp et al, 1982;Wilkerson et al, 2004b;Wilkerson et al, 2004a) •min -1 -a common finding in well-trained athletes (Maldonado et al, 2002;Svedenhag & Sjodin, 1984;Thomas et al, 2005). Relating the findings of some of these studies to models of middledistance running performance of highly trained athletes could potentially lead to misleading interpretations regarding the energetics of middle-distance running events.…”