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Belfry GR, Raymer GH, Marsh GD, Paterson DH, Thompson RT, Thomas SG. Muscle metabolic status and acid-base balance during 10-s work: 5-s recovery intermittent and continuous exercise. J Appl Physiol 113: 410-417, 2012. First published May 17, 2012; doi: 10.1152/japplphysiol.01059.2011.-Gastrocnemius muscle phosphocreatine ([PCr]) and hydrogen ion ([H+]) were measured using P-31-magnetic resonance spectroscopy during repeated bouts of 10-s heavy-intensity (HI) exercise and 5-s rest compared with continuous (CONT) HI exercise. Recreationally active male subjects (n = 7; 28 yr +/- 9 yr) performed on separate occasions 12 min of isotonic plantar flexion (0.75 Hz) CONT and intermittent (INT; 10-s exercise, 5-s rest) exercise. The HI power output in both CONT and INT was set at 50% of the difference between the power output associated with the onset of intracellular acidosis and peak exercise determined from a prior incremental plantar flexion protocol. Intracellular concentrations of [PCr] and [H+] were calculated at 4 s and 9 s of the work period and at 4 s of the rest period in INT and during CONT exercise. [PCr] and [H+] (mean +/- SE) were greater at 4 s of the rest periods vs. 9 s of exercise over the course of the INT exercise bout: [PCr] (20.7 mM +/- 0.6 vs. 18.7 mM +/- 0.5; P < 0.01); [H+] (370 nM +/- 13.50 vs. 284 nM +/- 13.6; P < 0.05). Average [H+] was similar for CONT vs. INT. We therefore suggest that there is a glycolytic contribution to ATP recovery during the very short rest period (<5 s) of INT and that the greater average power output of CONT did not manifest in greater [H+] and greater glycolytic contribution compared with INT exercise.
- 出版日期2012-8
