Summary: | This study investigates the relationship between peak force and rate of force development (RFD) obtained from maximal voluntary isometric contraction (MVC) of the back muscles and the power produced during a loaded lifting task. A group of 27 resistance-trained and 41 recreationally physically active men performed a maximal isometric strength test of the back muscles and a deadlift to high pull while lifting progressively increasing weights. Peak RFD correlated significantly with the peak and mean power produced during a deadlift to high pull with lower weights (from 20 to 40 kg), with r values ranging from .941 to .673 and from .922 to .633. The r 2 values ranged from .89 to .45 and from .85 to .40, explaining 89%–45% and 85%–40% of total variance. There were also significant relationships between MVC peak force and peak and mean values of power produced during a deadlift to high pull with weights ≥60 kg ( r in range from .764 to .888 and from .735 to .896). Based on r 2 , a moderate-to-high proportion of variance was explained (58%–79% and 54%–80%). These findings indicate that peak RFD obtained from MVC of the back muscles may be predictive of power performance during a lifting task at light loads. In addition to MVC peak force produced by back muscles, the ability of subjects to develop a high force in a short time should be evaluated in order to gain deeper insight into a loaded lifting performance, namely, in those prone to low back pain.
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