Muscular performance characterization in athletes: a new perspective on isokinetic variables

Abstract

Background: Isokinetic dynamometry allows the measurement of several variables related to muscular performance, many of which are seldom used, while others are redundantly applied to the characterization of muscle function. Objectives: The present study aimed to establish the particular features of muscle function that are captured by the variables currently included in isokinetic assessment and to determine which variables best represent these features in order to achieve a more objective interpretation of muscular performance. Method: This study included 235 male athletes. They performed isokinetic tests of concentric knee flexion and extension of the dominant leg at a velocity of 60º/s. An exploratory factor analysis was performed. Results: The findings demonstrated that isokinetic variables can characterize more than muscle torque production and pointed to the presence of 5 factors that enabled the characterization of muscular performance according to 5 different domains or constructs. Conclusions: The constructs can be described by torque generation capacity; variation of the torque generation capacity along repetitions; movement deceleration capacity; mechanical/physiological factors of torque generation; and acceleration capacity (torque development). Fewer than eight out of sixteen variables are enough to characterize these five constructs. Our results suggest that these variables and these 5 domains may lead to a more systematic and optimized interpretation of isokinetic assessments.

Muscle Strength is Impaired in Men but not in Women Living with HIV Taking Antiretroviral Therapy

“…Also, in the isokinetic muscle strength evaluation, the acceleration and deceleration time values are related, among other factors, to muscle activation [28,36]. Acceleration time indicates the neuromuscular ability to move a limb from rest position to predetermined isokinetic speed, and may be an indicator of neuromuscular capacity to develop torque quickly; lower values of this variable may represent higher muscle fibre recruitment capacity of tested muscles [37]. Moreover, deceleration time represents the total time to reduce isokinetic velocity at the end of range of motion, and indicates the neuromuscular ability to control the movement eccentrically [38].…”

Kinesiotaping Diminishes Delayed Muscle Soreness but does not Improve Muscular Performance

“…Peak torque has been the most widely reported and discussed variable characterizing muscular performance; however, it is limited to the description of torque generation capacity at a single point in the range of motion [42,43]. Conversely, the variable muscular work provides information on the ability of the muscle to generate torque throughout the entire range of motion [44]. Within that context, individuals able to generate high peak torque do not systematically exhibit the greatest values for muscular work.…”

“…Therefore, Amaral, et.al. [44] propose that these two variables best rep-resent the construct of torque generation capacity of skeletal muscle, allowing an accurate examination of muscle performance to identify specific deficits, or to assess the results of interventions. Our study showed a decrease of ̴30 % not only on the isokinetic peak torque (60 °/s) but also on muscular work 48h after exercise.…”

Neuromuscular performance of maximal voluntary explosive concentric contractions is influenced by angular acceleration

“…9 However, in contrast to typical isovelocity dynamometer testing, natural movements such as those listed above are characterized by limb acceleration, and a recent factor analysis study found that the capacity to accelerate a limb is one of five factors that characterize neuromuscular performance of athletes. 10 Accordingly, isometric and concentric RTD likely represent different aspects of explosive torque production, but to date very little is known about the influence of varying accelerations on torque production during maximum voluntary explosive concentric contractions.…”