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Updated: Jan 8, 2026

Determining the Contribution of the Energy Systems During Exercise
Published on: March 20, 2012
Dynamics of the Power-Duration Relationship during Intermittent Team Sports Exercise
Matthew I Black1, James A Lewis1, Yujie Liu1
1Public Health and Sports Science, University of Exeter Medical School, St Luke's Campus, Exeter, UNITED KINGDOM.
Purpose:
To 1) determine whether critical power (CP), W' and W' reconstitution kinetics (W' REC ) are altered by high-intensity team-sport specific intermittent exercise; 2) examine the accuracy with which W' balance (W' BAL ) is estimated by the W' BAL model; 3) examine whether physiological variables assessed during ramp incremental exercise and the 3-min all-out test, explain exercise-induced changes in the power-duration relationship.
Methods:
CP, W', and W' REC were determined during a repeated all-out test, which comprised a 3-min all-out test and a 2-min all-out test, separated by 90 s, in 13 recreationally active team-sport players. The test was performed in a rested condition (control) and immediately following a 40-min (40-IST) and 80-min (80-IST) intermittent sprint test.
Results:
CP assessed after the 40-IST (222 ± 57 W) and 80-IST (213 ± 49 W) were not different from control (222 ± 52 W; P > 0.05). W' REC was also not significantly different from control (0.08 ± 0.02 kJ·s -2 ) after the 40-IST (0.07 ± 0.02 kJ·s -2 ) or 80-IST (0.07 ± 0.02 kJ·s -2 ; P > 0.05). W' was lower than control (13.5 ± 4.0 kJ) after the 40-IST (10.1 ± 4.0 kJ) and 80-IST (9.1 ± 3.5 kJ) (both P < 0.05). After the 40-IST, W' BAL was not significantly different from the value predicted from the W' BAL model (10.9 ± 2.4 kJ; P > 0.05), but W' BAL was overestimated by the model following the 80-IST (10.7 ± 2.6 kJ; P < 0.05). There were considerable interindividual differences in the changes in the power-duration relationship following exercise, which were not related to physiological variables assessed in the control condition.
Conclusions:
CP and W' REC are not altered after intermittent exercise, but W' is decreased, with considerable heterogeneity in the changes in the power-duration relationship between individuals. These results have important implications for the application of the W' BAL model to describe intermittent exercise performance.
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