CROSS-SECTIONAL AND LONGITUDINAL USES OF ISOINERTIAL, ISOMETRIC, AND ISOKINETIC DYNAMOMETRY

The purposes of this investigation were to assess whether maximal isoi nertial (triceps pushdown [TP] and triceps extension [TE]), isometric and isokinetic (1.04, 2.08, 3.14, 4.16, and 5.20 rad . s(-1)) forearm extension strength measures: 1) presented statistical generality when they were correlated prior to and following 4, 8, and 12 wk of resista nce training; 2) were similarly affected by training; and 3) presented statistical generality when their changes as a consequence of trainin g were intercorrelated. Fifteen men (11 experimental and 4 controls) w ithout a history of resistance training participated in the study. Tra ining involved four sets of 8-12 repetitions, each followed by 90-s re covery, at 70-75% one repetition maximum (IRM), three Ones a week, for 12 wk. Training incorporated the TP, close-grip bench press, and tric eps kickback exercises. Prior to and after 4, 8, and 12 wk of training , the intercorrelations among the TP, isometric, and isokinetic indice s almost always achieved statistical generality (i.e., r(2) > 0.5). It was concluded that the strength measures generally discriminated simi larly between subjects. However, the sensitivity of the strength measu res to the effects of training were dissimilar. While all strength ind ices increased with the training, the timing (isoinertial prior to iso metric and isokinetic adaptations) and magnitude (TP>TE> isometric>iso kinetic) of these adaptations varied greatly. None of the intercorrela tions between changes in the strength indices achieved statistical gen erality. Furthermore, factor (F)-analyses on these changes indicated t hat in the initial and later stages of training, there were three and four discrete factors, respectively, accounting for strength developme nt. These factors were thought to reflect differential effects of trai ning on the structural, neural (including learning), and mechanical me chanisms underpinning each strength index. Possible applications of th is research design in better understanding strength development were a lso canvassed.