The effects of short work vs. longer work periods within intermittent exercise on (V) over dotO(2p) kinetics, muscle deoxygenation, and energy system contribution

作者：McCrudden Michael C; Keir Daniel A; Belfry Glen R^*

来源：Journal of Applied Physiology, 2017, 122(6): 1435-1444.

DOI：10.1152/japplphysiol.00514.2016

• energy systems
• intermittent exercise
• near-infrared spectroscopy
• O-2 on-kinetics
• recovery

We examined the effects of inserting 3-s recovery periods during high-intensity cycling exercise at 25-s and 10-s intervals on pulmonary oxygen uptake ((V) over dotO(2p)), muscle deoxygenation [deoxyhemoglobin (HHb)], their associated kinetics (tau), and energy system contributions. Eleven men (24 +/- 3 yr) completed two trials of three cycling protocols: an 8-min continuous protocol (CONT) and two 8-min intermittent exercise protocols with work-to-rest periods of 25 s to 3 s (25INT) and 10 s to 3 s (10INT). Each protocol began with a step-transition from a 20-W baseline to a power output (PO) of 60% between lactate threshold and maximal (V) over dotO(2p) (Delta 60). This PO was maintained for 8 min in CONT, whereas 3-s periods of 20-W cycling were inserted every 10 s and 25 s after the transition to Delta 60 in 10INT and 25INT, respectively. Breath-by-breath gas exchange measured by mass spectrometry and turbine and vastus lateralis [HHb] measured by near-infrared spectroscopy were recorded throughout. Arterialized-capillary lactate concentration ([Lac(-)]) was obtained before and 2 min postexercise. The tau(V) over dotO(2p) was lowest (P < 0.05) for 10INT (24 +/- 4 s) and 25INT (23 +/- 5 s) compared with CONT (28 +/- 4 s), whereas HHb kinetics did not differ (P > 0.05) between conditions. Postexercise [Lac(-)] was lowest (P < 0.05) for 10INT (7.0 +/- 1.7 mM), was higher for 25INT (10.3 +/- 1.9 mM), and was greatest in CONT (14.3 +/- 3.1 mM). Inserting 3-s recovery periods during heavy-intensity exercise speeded (V) over dotO(2p) kinetics and reduced overall (V) over dotO(2p), suggesting an increased reliance on PCr-derived phosphorylation during the work period of INT compared with an identical PO performed continuously.
NEW & NOTEWORTHY We report novel observations on the effects of differing heavy-intensity work durations between 3-s recovery periods on pulmonary oxygen uptake ((V) over dotO(2p)) kinetics, muscle deoxygenation, and energy system contributions. Relative to continuous exercise, (V) over dotO(2p) kinetics are faster in intermittent exercise, and increased frequency of 3-s recovery periods improves microvascular O-2 delivery and reduces (V) over dotO(2p) and arterialized-capillary lactate concentration. The metabolic burden of identical intensity work is altered when performed intermittently vs. continuously.

• 出版日期2017-6