Abstract
The relationship between work rate (overhead dot W) and time to exhaustion (t) during intense exercise is commonly described by either a hyperbolic function (NLin), t = W'/( overhead dot W - overhead dot W-cp), or by its linear equivalent (LinW) W-lim = W' + overhead dot Q-cp(t). The parameter overhead dot W-cp (critical power) has been described as an inherent characteristic of the aerobic energy system, while W' has been shown to be a rapid estimate of anaerobic work capacity. Recent studies have demonstrated that oral supplementation of creatine monohydrate (CrH-2O) increases total muscle creatine stores, and have linked these increases to improved performances in intense intermittent exercise. This study was conducted to determine the effect of CrH-2O supplementation on estimates of W' and overhead dot W-cp derived from the NLin and LinW equations, and to determine the effect of CrH-2O on t in exhaustive constant power exercise of different intensities. Fifteen active but untrained university students completed three phases of testing on a cycle ergometer: (1) familiarization, three learning trials, (2) baseline determination of W' and overhead dot W-cp, four bouts performed at a overhead dot W selected to elicit fatigue in 90-600 s, and (3) experimental determination of W' and overhead dot W-cp, four bouts performed at the same overhead dot Q as baseline, but performed after 5 days of ingesting either a placebo (4 times 6 g of glucose/day) or CrH-2O (4 times 5 g of CrH-2O and 1 g glucose/day). Testing was administered in a double-blind manner. Analyses of covariance revealed a significant effect for CrH-2O on both estimates of W' (NLin, P = 0.04; LinW, P lt 0.0 1), but not on estimates of overhead dot W-cp (NLin, P = 0.37; LinW; P = 0.30). Within groups, t was significantly different for only CrH-2O at the two highest overhead dot Ws (P = 0.04). It is concluded that oral ingestion of CrH-2O increases estimates of W' due to an improved t at the shorter, more intense exercise bouts.
Original language | English |
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Pages (from-to) | 360-365 |
Number of pages | 6 |
Journal | European Journal of Applied Physiology |
Volume | 77 |
Issue number | 4 |
DOIs | |
Publication status | Published - 1998 |
Keywords
- Critical Power
- Animals
- Sports Medicine
- (Metabolism--Energy and Respiratory Metabolism)
- General and Miscellaneous--General)
- General and Miscellaneous--Exercise and Physical Therapy (1970- ))
- Mammals
- Human
- Humans
- Time To Exhaustion
- High-Intensity Cycling
- Chordates
- Aerobic Capacity
- Creatine
- Oral Ingestion
- Peptides and Amino Acids (1972- ))
- Primates
- (Nutrition--Proteins
- Vertebrates
- Research Article
- (Physiology
- Work Rate-Time Relationship