Oxygen uptake plateau occurrence depends on oxygen kinetics and oxygen deficit accumulation

Abstract

We tested the hypothesis that participants with an oxygen uptake (normalV˙normalO2) plateau during incremental exercise exhibit a lower VO2‐deficit (VO2DEF)‐accumulation in the submaximal intensity domain due to faster ramp and square wave O2‐kinetics. Twenty‐six male participants performed a standard ramp test (increment: 30 W·min−1), a ramp test with an individualized ramp slope and a two‐step (moderate and severe) square wave exercise followed by a normalV˙normalO2max ‐verification bout. VO2DEF was calculated by the difference between individualized ramp test trueV˙O2 and trueV˙O2‐demand estimated from steady‐state trueV˙O2‐kinetics. Twenty‐four participants verified their trueV˙O2max in the verification test. Ten of them showed a plateau in the individualized ramp test. VO2DEF at the end of this ramp test (4.34 ± 0.60 vs 4.54 ± 0.43 L) was not different between the plateau and the non‐plateau group (P > 0.05). The plateau group had a significantly (P < 0.05) lower VO2DEF 2 minutes before termination of the individualized ramp test (2.24 ± 0.40 vs 2.78 ± 0.33 L). This coincided with a shorter mean response time (43 ± 9 vs 53 ± 7 seconds), a higher increase in trueV˙O2 per W (10.1 ± 0.2 vs 9.2 ± 0.5 mL·min−1·W−1) at the individualized ramp test as well as shorter time constants of moderate (36 ± 6 vs 48 ± 7 seconds) and severe (62 ± 9 vs 86 ± 10 seconds) square wave kinetics (all P < 0.05). We conclude that the trueV˙O2‐plateau occurrence requires a fast trueV˙O2‐kinetics and a low VO2DEF‐accumulation at intensities below trueV˙O2max.

Effect of intensive prior exercise on muscle fiber activation, oxygen uptake kinetics, and oxygen uptake plateau occurrence

“…Thus, it seems to be likely that the potential for an increase in the -plateau incidence in the primed condition is caused by an increase in rather than an increase or sparing of anaerobic capacity. This alternative explanation would support the hypothesis that the -plateau is affected by -kinetics (Niemeyer et al 2019 ). However, no such analysis has previously been reported.…”

“…As recently demonstrated, participants with a V O 2 -plateau had lower time constants of V O 2 square wave kinetics, but also steeper slopes of the V O 2 -workload-relationship ( ΔVO 2 ∕ΔP ) in incremental ramp tests (Niemeyer et al 2019). It is well known that the overall V O 2 response kinetics is accelerated after priming exercise bouts in the heavy or severe intensity domain (Bailey et al 2009;Burnley et al 2000Burnley et al , 2006.…”

“…This interpretation is based on studies that reported a slower accumulation of anaerobic metabolites following a heavy or severe priming bout (Bangsbo et al 2001 ; Layec et al 2009 ), suggesting a potential sparing of anaerobic capacity. Because of a rather slow time-dependent behavior of , there is a continuous accumulation of deficit during incremental exercise tests (Niemeyer et al 2019 ; Pouilly and Busso. 2008 ), which lead to an accumulation of anaerobic metabolites up to the individual tolerable limit (Raymer et al 2007 ).…”

“…Since the ramp test response is modulated by the time constant and gain of overall kinetics, but also by the intensity-dependent increase in these parameters (Wilcox et al 2016 ) in incremental ramp tests this led to an increase in at workloads below and/or above P GET (Jones and Carter 2004 ; Boone et al 2012 ). At a given , a higher results in faster attainment of and therefore potentially contributes to the development of a -plateau despite a similar P max (Niemeyer et al 2019 ). Thus, it seems to be likely that the potential for an increase in the -plateau incidence in the primed condition is caused by an increase in rather than an increase or sparing of anaerobic capacity.…”

Verification-phase tests show low reliability and add little value in determining V̇O2max in young trained adults

“…A _ VO 2 -plateau was defined as Delta-_ VO 2 < 125 mL between the oxygen uptake in the last 25 W and the second-to-last 25 W of the CPET [4]. Based on the assumption that _ VO 2 increases approximately 10 mL/min per Watt in the submaximal intensity domain [24] a _ VO 2 increase of 250 mL/min is expected between the last 25 W and the second-to-last 25 W. The cut-off was chosen at 50% of the expected increase of _ VO 2 as recommended by Niemeyer et al [4].…”