Int J Sports Med 2008; 29(3): 217-224
DOI: 10.1055/s-2007-965125
Training & Testing

© Georg Thieme Verlag KG Stuttgart · New York

Diurnal Variation in Maximal and Submaximal Strength, Power and Neural Activation of Leg Extensors in Men: Multiple Sampling Across Two Consecutive Days

M. Sedliak1 , T. Finni1 , S. Cheng2 , T. Haikarainen1 , K. Häkkinen1
  • 1Department of Biology of Physical Activity, University of Jyväskylä, Jyväskylä, Finland
  • 2Department of Health Sciences, University of Jyväskylä, Jyväskylä, Finland
Further Information

Publication History

accepted after revision February 5, 2007

Publication Date:
05 July 2007 (online)

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Abstract

This study aimed to compare day-to-day repeatability of diurnal variation in strength and power. Thirty-two men were measured at four time points (07 : 00 - 08 : 00, 12 : 00 - 13 : 00, 17 : 00 - 18 : 00, and 20 : 30 - 21 : 30 h) throughout two consecutive days (day 1 and day 2). Power during loaded squat jumps, torque and EMG during maximal (MVC) and submaximal (MVC40) voluntary isometric knee extension contractions were measured. The EMG/torque ratio during MVC and MVC40 was calculated to evaluate neuromuscular efficiency. A significant time-of-day effect with repeatable diurnal patterns was found in power. In MVC, a significant time-of-day effect was present on day 2, whereas day 1 showed a typical but nonsignificant diurnal pattern. EMG and antagonist co-activation during MVC remained statistically unaltered, whereas neuromuscular efficiency improved from day 1 to day 2. A similar trend was observed in MVC40 neuromuscular efficiency with significant time-of-day and day-to-day effects. Unaltered agonist and antagonist activity during MVC suggests that modification at the muscular level was the primary source for the diurnal variation in peak torque. A learning effect seemed to affect data in MVC40. In conclusion, the second consecutive test day showed typical diurnal variation in both maximum strength and power with no day-to-day effect of cumulative fatigue.

References

MSc Milan Sedliak

Department of Biology of Physical Activity
University of Jyväskylä

P.O. Box 35

40014 Jyväskylä

Finland

Phone: + 35 81 42 60 20 58

Fax: + 35 81 42 60 20 11

Email: milan.sedliak@sport.jyu.fi