The acquisition of maximal isometric plantar flexor strength: a force-time curve analysis

A paradigm involving the static force-time curve was used to study the mechanisms through which gains in maximal isometric strength are achieved during repeated testing. Twelve males performed three maximal contractions of the plantar flexors on each of six test days. Each contraction was executed as rapidly as possible, with the force recorded on a rapidly moving pen recorder. Although highly significant increases in maximal plantar flexor strength occurred over the six days, no changes were seen in the maximal rate of tension development. However, assessment of the amount of force reached at absolute time intervals revealed that more force was attained at the early time intervals on the first few days of testing than on the later days, indicating a distinct change in the shape of the static force-time curve. Several neural mechanisms are suggested to explain the alteration in shape of the static force-time curve which accompanies the acquisition of maximal strength.