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Exercise Tolerance in Intermittent Cycling: Application of the Critical Power Concept

CHIDNOK, WEERAPONG1; DIMENNA, FRED J.1; BAILEY, STEPHEN J.1; VANHATALO, ANNI1; MORTON, R. HUGH2; WILKERSON, DARYL P.1; JONES, ANDREW M.1

Medicine & Science in Sports & Exercise: May 2012 - Volume 44 - Issue 5 - p 966–976
doi: 10.1249/MSS.0b013e31823ea28a
Applied Sciences

Purpose: This study tested the relevance of the critical power (CP) model for explaining exercise tolerance during intermittent high-intensity exercise with different recovery intensities.

Methods: After estimation of CP and W′ from a 3-min all-out test, seven male subjects completed, in randomized order, a cycle test to exhaustion at a severe-intensity constant-work-rate (S-CWR) and four cycle tests to exhaustion using different intermittent (“work–recovery”) protocols (i.e., severe–severe (S–S), severe–heavy (S–H), severe–moderate (S–M), and severe–light (S–L)).

Results: The tolerable duration of exercise in S-CWR was 384 ± 48 s, and this was increased by 47%, 100%, and 219% for S–H, S–M, and S–L, respectively (all P < 0.05). Consistent with this, compared with S-CWR (22.9 ± 7.4 kJ), the work done above the CP was significantly greater by 46%, 98%, and 220% for S–H, S–M, and S–L, respectively (all P < 0.05). The slope of the relationship between V˙O2 and time was significantly reduced for S–H, S–M, and S–L (0.09 ± 0.02, 0.09 ± 0.01, and 0.07 ± 0.02 L·min−2, respectively) compared with S-CWR (0.16 ± 0.03 L·min−2, P < 0.05). In addition, the slope of the relationship between integrated EMG and time showed a systematic decline for S–H, S–M, and S–L compared with S-CWR (P < 0.05).

Conclusions: These results indicate that, when recovery intervals during intermittent exercise are performed below the CP, exercise tolerance is improved in proportion to the reconstitution of the finite W′. The enhanced exercise tolerance with the lower-intensity recovery intervals was associated with a blunted increase in both V˙O2 and integrated EMG with time.

1Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke’s Campus, University of Exeter, Exeter, Devon, England, UNITED KINGDOM; and 2School of Sport and Exercise, Massey University, Palmerston North, NEW ZEALAND

Address for correspondence: Andrew M. Jones, Ph.D., College of Life and Environmental Sciences, University of Exeter, St. Luke’s Campus, Exeter, Devon, EX1 2LU, United Kingdom; E-mail: a.m.jones@exeter.ac.uk.

Submitted for publication July 2011.

Accepted for publication October 2011.

©2012The American College of Sports Medicine