The effect of glycogen depletion on the curvature constant parameter of the power-duration curve for cycle ergometry

A Miura, H Sato, H Sato, B J Whipp, Y Fukuba
Ergonomics 2000, 43 (1): 133-41
For high-intensity cycle ergometer exercise, the relation between power (P) and its tolerable duration (t) has been well characterized by the hyperbolic relationship: (P-thetaF) t = W', or P = W' (1/t)+thetaF, where thetaF may be termed the 'fatigue threshold'. The curvature constant (W') reflects a constant amount of work which is postulated to be equivalent to a finite energy store that relates to the oxygen-deficit: phosphagen pool, anaerobic glycolysis and oxygen stores. Compared to thetaF, the physiological nature of W' has received little consideration. The purpose of this study was therefore to establish the parameters of the power-duration curve (thetaF and W') for subjects in normal glycogen (NG) and glycogen depleted (GD) states. Seven healthy male subjects (aged 22 to 41 years) each performed four high-intensity square-wave exercise bouts on an electrically braked cycle ergometer under two different muscular glycogen content conditions, i.e. NG and GD states. Subjects performed the following exercise on the evening before the trial day to induce the GD state. Initially, they performed a 75-min cycling exercise at 60% of VO2max. After a 5-min rest period, they subsequently repeated a 1-min cycling bout at 115% of VO2max (separated by 1-min rest periods) until the subject could no longer maintain the prescribed pedal rate for the full minute. Subjects then reported to the laboratory after an overnight fast and performed a single high-intensity exercise bout. The GD procedure was repeated four times at 1-week intervals. In the GD state, the respiratory exchange ratio (RER) (VO2/VCO2) value during a recumbent control period prior to the trial was significantly lower than that in the NG state [GD: 0.84+/-0.02, NG: 0.94+/-0.04, mean +/- SD]. There was no significant difference for thetaF between GD and NG state [NG: 197.1+/-31.9 W, GD: 190.6+/-28.2 W]. W' in contrast was significantly reduced by the GD procedure [NG: 12.83+/-2.21 kJ, GD: 10.33+/-2.41 kJ]. The present results indicate that the muscular glycogen store seems to be an important determinant of the curvature constant (W') of the power-duration curve for cycle ergometry.

Full Text Links

Find Full Text Links for this Article


You are not logged in. Sign Up or Log In to join the discussion.

Trending Papers

Remove bar
Read by QxMD icon Read

Save your favorite articles in one place with a free QxMD account.


Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"