In:
Journal of Applied Physiology, American Physiological Society, Vol. 87, No. 1 ( 1999-07-01), p. 116-123
Abstract:
Five women and 3 men (29.8 ± 1.4 yr) performed dynamic knee-extension exercise inside a magnetic resonance system (means ± SE). Two trials were performed 7–14 days apart, consisting of a 4- to 5-min exhaustive exercise bout. To determine quadriceps cost of contraction, brief static and dynamic contractions were performed pre- and postexercise. 31 P spectra were used to determine pH and relative concentrations of P i , phosphocreatine (PCr), and βATP. Subjects consumed 0.3 g ⋅ kg −1 ⋅ day −1 of a placebo ( trial 1) or creatine ( trial 2) for 5 days before each trial. After creatine supplementation, resting ΔPCr increased from 40.7 ± 1.8 to 46.6 ± 1.1 mmol/kg ( P = 0.04) and PCr during exercise declined from −29.6 ± 2.4 to −34.1 ± 2.8 mmol/kg ( P = 0.02). Muscle static (ΔATP/N) and dynamic (ΔATP/J) costs of contraction were unaffected by creatine supplementation as well as were ATP, P i , pH, PCr resynthesis rate, and muscle strength and endurance. ΔATP/J and ΔATP/N were greatest at the onset of the exercise protocol ( P 〈 0.01). In summary, creatine supplementation increased muscle PCr concentration, which did not affect muscle ATP cost of contraction.
Type of Medium:
Online Resource
ISSN:
8750-7587
,
1522-1601
DOI:
10.1152/jappl.1999.87.1.116
Language:
English
Publisher:
American Physiological Society
Publication Date:
1999
detail.hit.zdb_id:
1404365-8
SSG:
12
SSG:
31
Bookmarklink