Are early and late rate of force development differently influenced by fast‐velocity resistance training?

Summary This study examined the effect of fast‐velocity concentric isokinetic resistance training ( FV ) on the rate of force development ( RFD ) at early (<100 ms) and late phases (>100 ms) of rising muscle force. Nine men participated in a 6‐week resistance training intervention for the lower body, and nine matched subjects participated as controls ( CON ). During concentric isokinetic (180°s −1 ) knee extension training, subjects were instructed to do each contraction ‘as fast and forcefully as possible’. Maximal muscle strength ( MVC ) and RFD (0–10, 0–20, …, 0–250 ms from the onset of contraction) were measured during maximal voluntary isometric contraction of the knee extensors ( KE ). There were no significant changes in MVC of KE in both groups after intervention ( FV  = 314·2 ± 101·1 versus 338·7 ± 88·0 N∙m, P >0·05; CON  = 293·3 ± 94·8 versus 280·0 ± 72·2 N∙m, P >0·05). The RFD increased 39–71% at time intervals up to 90 ms from the onset of the contraction ( P < 0·05), whereas no change occurred at later time intervals. Similarly, relative RFD (i.e.% MVC ∙s −1 ) ( RFD r) increased 33–56% at time intervals up to 70 ms from the onset of the contraction ( P <0·05). It can be concluded that a short period of resistance training performed with concentric fast‐velocity isokinetic muscle contractions is able to enhance RFD and RFD r obtained at the early phase of rising muscle force.