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Fiber Type Composition and Capillary Density in Relation to Submaximal Number of Repetitions in Resistance Exercise

Terzis, Gerasimos1; Spengos, Konstantinos2; Manta, Panagiota2; Sarris, Nickos1; Georgiadis, Giorgos1

Journal of Strength & Conditioning Research: May 2008 - Volume 22 - Issue 3 - pp 845-850
doi: 10.1519/JSC.0b013e31816a5ee4
Original Research

The purpose of this study was to investigate the relationship between skeletal muscle fiber type composition and the maximum number of repetitions performed during submaximal resistance exercise. Twelve young men performed a maximum repetitions test at 85% of 1 repetition maximum (1RM) in the leg press, which was repeated after 1 week. Seven days after the second 85% 1RM test, they performed a maximum repetitions test at 70% of 1RM in the leg press. This test, at 70% 1RM, was repeated 7 days later. One week before the initiation of the testing sessions, a biopsy sample was obtained from the vastus lateralis muscle and analyzed for fiber type distribution, fiber cross-sectional area, and capillary density (capillaries·mm−2). A low and nonsignificant relationship was found between the fiber type distribution or percent fiber type area and the number of repetitions performed at either 70% or 85% 1RM. Moreover, the number of repetitions performed at 70% or 85% of 1RM was not related significantly with 1RM strength. In contrast, the number of repetitions performed at 70% 1RM was significantly correlated with the number of capillaries per mm2 of muscle cross-sectional area (r = 0.70; p = 0.01). These results suggest that fiber type composition is not the major biological variable regulating the number of repetitions performed in submaximal resistance exercise. Rather, it seems that submaximal strength performance depends on muscle capillary density, which is linked with the endurance capacity of the muscle tissue.

1Track and Field Division, Department of Physical Education and Sport Science; 2Neurology Clinic, Aiginition Hospital, Division of Public Health, Psychiatry, and Neurology, Medical School, University of Athens, Athens, Greece

Address correspondence to Gerasimos Terzis, gterzis@phed.uoa.gr.

© 2008 National Strength and Conditioning Association