Impact of Hypohydration and Creatine Supplementation on Skeletal Muscle Performance and Metabolism.
Abstract
Two studies were done using 3 iP magnetic resonance spectroscopy to examine the separate effects of hypohydration and dietary creatine supplementation on muscle metabolism and performance. Volunteers performed supine single-leg knee extension exercise in a 1.5 Tesla whole body magnetic resonance spectroscopy (MRS) system. For the hypohydration study, exercise was performed to exhaustion when euhydrated and 4% hypohydrated. Hypohydration reduced (P <0.05) time to fatigue 15% (EU =251+67 HY=213 +52 Sec; Isd). Muscle pH and Pi/BATP were similar during exercise and at exhaustion regardless of hydration state. It was concluded that hypohydration reduces muscle endurance and the effects appear independent of H + and Pi concentration. For the creatine studies, 3 repeat bouts of high-intensity exercise were performed before and after 5 days of creatine supplementation (0.3 g'kg-1-day-i). Middle-aged persons (5814 yr) had lower resting PCr/BATP compared to the young group (6.3610.94 vs. 7.18+0.93, p<O.05) and a lower mean PCr resynthesis rate for bouts 1 and 2 (18.1+3.5 vs. 23.2+6.0 mmol'kg wet wt-1'min-1, p<O.05). After creatine supplementation, resting PCr/BATP increased 15% (p<0.05) in the young group and 29% (p<0.05) in the middle-aged group (8.3+1.3 vs. 8.311.0) eliminating the difference between groups. Mean PCr resynthesis rate also increased in the middle-aged group (p <0.05) during the creatine trial to a level not different from the young group (24.3+3.8 vs. 24.2 + 3.2 mmol kg wet wt- 1 min- 1). Time to exhaustion was increased in the young group after creatine supplementation (122136 vs. 162+59 s, p <0.05) but did not improve in the middle-aged group (113 + 31 vs. 144181 s, p = 0.2).
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1998
- Accession Number
- ADA341546
Entities
People
- Ferenc A. Jolesz
- Gary P. Zientara
- Ralph P. Mattot
- Scott J. Montain
- Sinclair A. Smith
Organizations
- United States Army Research Institute of Environmental Medicine