Methodological considerations for assessing whole-body strength capacity through isometric dynamometry.

The present study aimed to explore the possibility of comprehensively assessing whole-body muscle strength by testing as few muscle groups as possible, using a single testing method (isometric or isokinetic dynamometry) and a single variable (maximal force or rate of force development). Knee, hip, shoulder and elbow extensors and flexors were evaluated in males with high (n = 26) and low strength levels (n = 32). The principal component analysis revealed three factors that explained 62.5% of the total variance, while the main factors were loaded by the different testing methods and strength variables for the muscles acting on the knee (first component), hip (second component) and arm joints (third component). These results were confirmed by a three-way ANOVA which revealed a significant factor of group (P < 0.001) and the interaction test type × group (P = 0.002), but not of test type (P = 0.644), muscle group (P = 0.999), or their interactions (P > 0.205). The correlations of strength outcomes across the muscles ranged from trivial to very large (r range = -0.17, 0.84), being generally higher for the antagonistic muscles. Overall, a comprehensive assessment of whole-body muscle strength can be obtained using isometric dynamometry and maximal force, but it should consider at least one muscle group from the antagonistic pair.

Isokinetic Testing: Sensitivity of the Force-Velocity Relationship Assessed through the Two-Point Method to Discriminate between Muscle Groups and Participants' Physical Activity Levels.

BACKGROUND: Isokinetic testing has been routinely used to assess the capacities of individual muscle groups. In this study we aimed to evaluate the sensitivity of the force-point (F-v) relationship assessed through the two-point method to discriminate between antagonist muscle groups and males with different physical activity levels. METHODS: The concentric force output of the knee, hip, elbow, and shoulder flexors and extensors of 27 active and 13 non-active men was recorded at 60 and 180°/s to determine the F-v relationship parameters (maximum force [F0], maximum velocity [v0], and maximum power [Pmax]). RESULTS: F0 and Pmax were higher for knee extensors (effect size [ES] = 1.97 and 0.57, respectively), hip extensors (ES = 2.52 and 0.77, respectively), and shoulder flexors (ES = 1.67 and 0.83, respectively) compared to their antagonist muscles, while v0 was higher for knee flexors compared to knee extensors (ES = 0.59). Active males revealed higher F0 for knee extensors (ES = 0.72) and knee flexors (ES = 0.83) and higher Pmax for knee flexors (ES = 0.70), elbow extensors (ES = 0.83) and shoulder extensors (ES = 0.36). CONCLUSIONS: The sensitivity of the two-point method for testing the maximal mechanical capacities was high for the knee, moderate for the hip and shoulder, and low for the elbow joint.