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The Effects of Constant External Resistance Exercise and Isokinetic Exercise Training on Work-induced Hypertrophy.

Pearson, David R.; Costill, David L.
Journal of Strength & Conditioning Research: August 1988
Article: PDF Only

Six male subjects (26.0+/-3.1 years) performed an exercise regimen of repeated knee extension exercises in an attempt to induce size and strength changes in the quadriceps muscle (thigh). The left thigh was trained using a progressive constant external resistance exercise (CERE) lifting protocol and the right thigh was trained using an isokinetic (ISK) device. The total amount of torque produced by each protocol was the same. Knee extensions were performed at a velocity common to the CERE (120 deg/sec). Girth measurements, corrected for subcutaneous fat, and expressed as thigh volumes (cc), showed a significant hypertrophy of the posttrained CERE thigh (3300.67+/-526.67) compared to the pretrained CERE thigh (3044.13+/-448.50). No significant difference was found between pre- and posttrained ISK thigh volumes. The mean CERE (36.0+/-0.0) and ISK repetitions (64.54+/-13.61) necessary to produce equals work bouts (based on total torque produced) were significantly different. Strength gains as measured with the CERE and ISK device were specific to the training mode. The CERE thigh showed a significant strength (kg) gain when tested on a CERE device; the ISK thigh did not. However, the ISK thigh gained significant strength (kg.m) at all testing velocities (60, 180 and 240 deg/sec) while the CERE thigh did not.

These data would indicate: 1) the suggested superiority of CERE training versus ISK training for producing hypertropby of the thigh at a training velocity common to CERE (120 deg/sec); 2) CERE training is more intense than ISK training for equal work bouts at a training velocity common to CERE; and 3) strength gains are specific to training and to the mode of testing.

(C) 1988 National Strength and Conditioning Association