The Effect of Isokinetic and Weight Strength Training in Young Men and Women

Abstract

<p>Six males (M, 21.2 ± 1.2 y) and 6 females (F, 20.3 ± .8 y) trained, by random assignment, the elbow flexors of one arm on an isokinetic device (ID, Hydra-Gym, Belton,T exas) and the other arm on weight device (WD, Rubicon Ind., Stoney Creek, Ont.). Training consisted of 5 sets of 10 maximal effort repetitions at the slowest velocity on the ID and 5 sets of 8-12 repetitions maximum on the WD, 3 times per week for 20 weeks.0</p> <p>Needle biopsy samples were obtained from biceps brachii before and after training and analysed for fibre type distribution and fibre area. CT scans were taken of the upper arm and analysed for bicep, brachialis and total flexor cross-sectional area. Strength measurements on both arms were taken at 2 week intervals through the training period on the ID (3 velocities) and the WD (1RM) as well as a Cybex dynamometer (@ 30, 120, 180, 240 °/s) and isometric dynamometer (ISD) (@ 75, 90, 105, 120, 135, 150, 165°). Contractile properties were obtained from isometric twitch measurements and analysed for peak torque (PT), time to peak torque (TPT), 1/2 relaxation time (1/2 RT), Maximum rate of torque development (MRTD) and maximum rate of torque relaxation ( MRTR).</p> <p>Fibre areas showed no change in absolute values (um ²) however relative fibre area increased (+12.1%, p<.07), the change being most evident in the Type II fibres (+20.8%, p<.06). Bicep area increased 9% following training. Brachialis area increased in absolute and relative (41%) terms with the largest increase in M and F trained on the WD (p<.05). Total flexor area increased significantly with no differences between gender or training mode. Cybex peak torque increased significantly in F (14.1%) but not in M after training. Strength measured on the WD and ID increased significantly in all conditions. WD and ID training produced similar increases in strength measured on the ID. Strength measured on the WD increased more with WD (102.9%) than ID (58.6%) training. M made greater absolute increases in strength on the WD (88.0 vs 69.8 N) and the 10 (266.2 vs 236.8 N) than F, whereas F made greater relative strength increases on the ID (99.3 vs 44.3%), WO (116.0 vs 45.5%) and ISO (22.5 vs 6.5%) than M. PT increased at 14 weeks and remained elevated to some extent, post training. MRTO and MRTR followed the pattern of PT. No change was observed in TPT or 1/2 RT with training. It was concluded that: (1) WD training causes greater gains in training specific strength; (2) M make greater absolute but smaller relative increases in strength than F; (3) WD training is more effective in increasing muscle size than 10 training; (4) F can make comparable absolute gains in muscle mass to M; (5) PT increased with training, in part because of increased muscle mass; (6) Training of this intensity and duration does not affect the time-related contractile characteristics of human muscle.</p>