The y-intercept of the critical power function as a measure of anaerobic work capacity

Jenkins, David G. and Quigley, Brian M. (1991) The y-intercept of the critical power function as a measure of anaerobic work capacity. Ergonomics, 34 1: 13-22. doi:10.1080/00140139108967284


Author Jenkins, David G.
Quigley, Brian M.
Title The y-intercept of the critical power function as a measure of anaerobic work capacity
Journal name Ergonomics   Check publisher's open access policy
ISSN 0014-0139
1366-5847
Publication date 1991-01-01
Sub-type Article (original research)
DOI 10.1080/00140139108967284
Volume 34
Issue 1
Start page 13
End page 22
Total pages 10
Place of publication Essex, United Kingdom
Publisher Taylor & Francis
Language eng
Formatted abstract
When bouts of muscular work are performed to exhaustion at different intensities, the slope of the regression of maximal work (work limit) on maximal time (time limit) is referred to as critical power (CP). The y-intercept of this function is considered to represent anaerobic work capacity (AWC). The purpose of this investigation was to examine the relationship between the y-intercept from the critical power curve and measures of AWC (total work accomplished, maximal blood lactate and post-exercise venous blood pH) gained from repeated, maximal exercise. Nine male volunteers of moderately high training status (V̇O2 max 4.45 ± 0.25 l/min) completed three cycle ergometer tests to exhaustion (at 300, 350 and 400 W) for the determination of CP. A second cycle ergometer task involved repeated maximal effort (against 0.075 N/kg body mass) over five 1 min periods. Five min of passive recovery separated each exercise bout, at the end of which capillary blood was collected for lactate analysis. On completion of the fifth bout, venous blood was sampled for the determination of blood pH. Total accumulated work provided a performance estimate of AWC which, together with blood lactate and pH, was compared to the y-intercept. Correlation analysis revealed a significant relation between the y-intercept and total work accomplished (r = 0.74; p < 0.05), while post-exercise venous blood pH was positively related to both the y-intercept (r = 0.92; p < 0.01) and the accumulated work recorded (r = 0.92, p < 0.01). No significant correlation between peak blood lactate and work was found (r = 0.16; ns), although a relation between post-exercise venus blood pH and V̇O2 max was established (r = 0.84; p < 0.05). The capacity for high intensity interval work was well represented by the y-intercept in active males. Furthermore, the relations between blood pH and both the y-intercept and accumulated work suggest that either improved buffering or a greater contribution of aerobic metabolism to the energy yield may have been responsible for the more successful performances in the interval exercise.

When bouts of muscular work are performed to exhaustion at different intensities, the slope of the regression of maximal work (work limit) on maximal time (time limit) is referred to as critical power (CP). The y-intercept of this function is considered to represent anaerobic work capacity (AWC). The purpose of this investigation was to examine the relationship between the y-intercept from the critical power curve and measures of AWC (total work accomplished, maximal blood lactate and post-exercise venous blood pH) gained from repeated, maximal exercise. Correlation analysis revealed a significant relation between the y-intercept and total work accomplished while post-exercise venous blood pH was positively related to both the y-intercept (r=0.92; p<0.01) and the accumulated work recorded (r=0.92; p<0.01). No significant correlation between peak blood lactate and work was found (r=0.16; ns), although a relation between post-exercise venous blood pH and VO2 max was established (r=0.84; p<0.05). The capacity for high intensity interval work was well represented by the y-intercept in active males. Furthermore, the relations between blood pH and both the y-intercept and accumulated work suggest that either improved buffering or a greater contribution of aerobic metabolism to the energy yield may have been responsible for the more successful performances in the interval exercise.
Keyword Critical power
Anaerobic work capacity
Bicycle ergometry test
Exercise test
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ
Additional Notes Version of record first published: 30 May 2007.

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Human Movement and Nutrition Sciences Publications
 
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Created: Wed, 09 Mar 2011, 18:50:16 EST