Effect of heavy-intensity 'priming' exercise on oxygen uptake and muscle deoxygenation kinetics during moderate-intensity step-transitions initiated from an elevated work rate.
We examined the effect of heavy-intensity 'priming' exercise on the rate of adjustment of pulmonary O2uptake (τV˙O2p) initiated from elevated intensities. Fourteen men (separated into two groups: τV˙O2p≤25s [Fast] or τV˙O2p>25s [Slow]) completed step-transitions from 20W to 45% lactate threshold (LT; lower-step, LS) and 45% to 90%LT (upper-step, US) performed (i) without; and (ii) with US preceded by heavy-intensity exercise (HUS). Breath-by-breath V˙O2pand near-infrared spectroscopy-derived muscle deoxygenation ([HHb+Mb]) were measured. Compared to LS, τV˙O2pwas greater (p<0.05) in US in both Fast (LS, 19±4s; US, 30±4s) and Slow (LS, 25±5s; US, 40±11s) with τV˙O2pin US being lower (p<0.05) in Fast. In HUS, τV˙O2pin Slow was reduced (28±8s, p<0.05) and was not different (p>0.05) from LS or Fast group US. In Slow, τ[HHb+Mb] increased (p<0.05) in US relative to HUS; this finding coupled with a reduced τV˙O2pindicates a priming-induced improvement in matching of muscle O2delivery-to-O2utilization during transitions from elevated intensities in those with Slow but not Fast V˙O2pkinetics.
Canadian Centre for Activity and Aging, London, ON, Canada; School of Kinesiology, The University of Western Ontario, London, ON, Canada.
Joshua P
JP
Nederveen
Canadian Centre for Activity and Aging, London, ON, Canada; School of Kinesiology, The University of Western Ontario, London, ON, Canada.
Daniel A
DA
Keir
Canadian Centre for Activity and Aging, London, ON, Canada; School of Kinesiology, The University of Western Ontario, London, ON, Canada.
Lorenzo K
LK
Love
Rehabilitation Clinical Trials Center, Division of Respiratory and Critical Care Physiology and Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA; Faculty of Biological Sciences, University of Leeds, Leeds, UK.
Harry B
HB
Rossiter
Canadian Centre for Activity and Aging, London, ON, Canada; School of Kinesiology, The University of Western Ontario, London, ON, Canada; Department of Physiology and Pharmacology, The University of Western Ontario, London, ON, Canada. Electronic address: jkowalch@uwo.ca.
John M
JM
Kowalchuk
D000328:Adult; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006801:Humans; D007700:Kinetics; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared
D010100:Oxygen
Muscle oxygenation; Near-infrared spectroscopy; O(2) uptake kinetics; Priming exercise