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Hormonal responses from concentric and eccentric muscle contractions.
Robert J Durand1, V Daniel Castracane, Daniel B Hollander
1Department of Kinesiology and Health Studies, Southeastern Louisiana University, Hammond, USA. Durandrj@pbrc.edu
Medicine and Science in Sports and Exercise
|June 5, 2003
Summary
Concentric exercise significantly boosts growth hormone (GH) more than eccentric exercise at the same load. Testosterone and free testosterone responses were similar for both contraction types during resistance training.
Area of Science:
- Exercise Physiology
- Endocrinology
- Sports Science
Background:
- Intense resistance exercise can acutely elevate anabolic hormones like testosterone (T), free testosterone (FT), and growth hormone (GH).
- Limited research exists on the acute endocrine responses to concentric (CON) versus eccentric (ECC) muscle actions during resistance training.
Purpose of the Study:
- To compare the acute anabolic hormonal responses to dynamic CON and ECC contractions across multiple exercises performed at the same absolute load.
- Investigate differences in T, FT, and GH concentrations following distinct contraction modes.
Main Methods:
- Ten young men completed two counterbalanced trials: one with CON contractions and one with ECC contractions.
- Subjects performed four sets of 12 repetitions of bench press, leg extension, military press, and leg curl at 80% of their 10-repetition maximum, with 90-second rest periods.
- Blood samples were collected pre-exercise, immediately post-exercise, and 15 minutes post-exercise.
Main Results:
- Both CON and ECC trials resulted in significant increases in GH, T, FT, and lactate.
- Growth hormone (GH) and lactate concentrations were significantly higher following the CON trial compared to the ECC trial.
- Testosterone (T) and free testosterone (FT) showed similar, small but significant increases after both CON and ECC trials.
Conclusions:
- Concentric (CON) exercise elicits a greater increase in growth hormone (GH) compared to eccentric (ECC) exercise when performed at the same absolute load.
- The heightened GH response to CON exercise is likely related to exercise intensity rather than the mode of contraction.
- Dynamic CON and ECC contractions at the same absolute workload produced comparable increases in T and FT, suggesting metabolic stress differences did not impact these hormones.