ISOMETRIC STRENGTH HAS LIMITED IMPLICATIONS FOR MOVEMENT PERFORMANCES
Nelson, A. G., McGuigan, M. R., & Winchester, J. B. (2008).The relationship between isometric and dynamic strength in college football players. ACSM 55th Annual Meeting Indianapolis. Presentation number 2152.
This study examined the relationships between measures of maximum isometric force, rate of force development, and one repetition maximum (1 RM) in Division I collegiate football players (N = 22). Maximum isometric force and rate of force development were determined from force-time curves generated from an isometric mid-thigh pull exercise. Measures of dynamic strength were represented by the 1 RM for squat, bench press, and power clean, as well as the 2 RM for the split jerk. Vertical jump and standing broad jump were also measured to provide an indication of explosive muscular power. Strong correlations were defined as any significant correlations where r > 0.6 or r < -0.6.
There were strong correlations between measures of maximum isometric force and the 1 RMs. The correlation between the power clean 1 RM and squat 1 RM also was strong. There were strong correlations between 2 RM split jerk and clean 1 RM, squat 1 RM, bench 1 RM, and maximum isometric force. There were no significant correlations with rate of force development for any variable.
Implication. The isometric mid-thigh pull test correlates well with 1 RM in college football players. The isometric mid-thigh pull provides an efficient method for assessing isometric strength in athletes. Rate of force development was not associated with isometric or 1 RM force development. However, rate of force development which is known to correlate with movement power and speed is not related to isometric force or single strength movements. Consequently, isometric force and 1 RM strength activities should not be expected to enhance speed of movement in functional activities that occur in American football or other high velocity sports.
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