The Utility of Isokinetic Dynamometry in the Assessment of Human Muscle Function

Abstract

Isokinetic dynamometry has become a favoured method for the assessment of dynamic muscle function in both clinical research and sports environments. Several indices, such as peak torque, are used in the literature to characterise individual, group or larger population performance via these sophisticated data acquisition systems. Research suggests that there are several competing demands on the design of the measurement protocol which may affect the measurement of isokinetic strength and subsequent suitability of data for meaningful evaluation and interpretation. There is a need to increase measurement rigour, reliability and sensitivity to a level which is commensurate with the intended application, via more elaborate multiple-trial protocols. However, this may be confounded by logistical and financial constraints or reduced individual compliance. The net effect of the interaction of such demands may be considered to be the utility of the isokinetic dynamometry protocol. Of the factors which impinge on utility, those which relate to reliability afford the most control by the test administrator. Research data suggest that in many measurement applications, the reliability and sensitivity associated with all frequently-used indices of isokinetic leg strength which are estimated via single-trial protocols, are not sufficient to differentiate either performance change within the same individual or between individuals within a homogeneous group. While such limitation may be addressed by the use of protocols based on 3 to 4 inter-day trials for the index of peak torque, other indices which demonstrate reduced reliability, for example the composite index of the ratio of knee flexion to extension peak torque, may require many more replicates to achieve the same level of sensitivity. Here, the measurement utility of the index may not be sufficient to justify its proper deployment.

Comprehensive nutritional status in recently diagnosed patients with inflammatory bowel disease compared with population controls

“…Prior to testing each subject underwent a 5 min warm-up period of aerobic ergometer cycling. The subjects were then ®xed to the testing apparatus, an (Gleeson & Mercer, 1996). The strength of m. quadriceps (extension) and of the hamstrings (¯exion) were measured.…”

Effects of acute fatigue on the volitional and magnetically-evoked electromechanical delay of the knee flexors in males and females

“…Optimal functioning of the knee flexors in particular is considered fundamental to the prevention of ACL injury (Gleeson and Mercer 1996;Johansson et al 1991;Rees 1994), however, a limited time frame exists whereby potentially harmful dynamic forces must be overcome by the most rapid response of the neuromuscular system in order to protect ligamentous tissue against injury (Gleeson et al 1998a;Huston and Wojtys 1996;Mercer et al 1998;Shultz et al 2001). For the ACL, the time frame from the initial application of such forces to the complete rupture of the ligament has been estimated at 300 ms (Rees, 1994).…”

Reproducibility of an isokinetic eccentric muscle endurance task

“…These data are in agreement with others who have demonstrated a 53% decrease in elbow flexors after 100 repeated eccentric actions (Linnamo, Bottas, & Komi, 2000) and repeated actions of the knee extensors (Brown, Child, Day, & Donnelly, 1997;MacIntyre, Reid, Lyster, Szasz, & McKenzie, 1996). However, others have shown that repeated eccentric muscle actions are extremely fatigue resistant despite high force production (Emery et al, 1994;Hortobagyi et al, 1996;Tesch, 1990 It has been suggested that an ICC of 0.88 or above and CV not exceeding ± 6% demonstrates good reliability in isokinetic strength testing (Gleeson & Mercer, 1996). The relative reliability for the WFI and TFI in the current study are lower than this recommended value for both the knee extensors and flexors.…”