32 expts. were made with 20 normal adult subjects to observe the effect of bimanual exercise on the functional capacity of the weaker limb. Work was done on 2 nearly identical ergographs and consisted of max. volitional wrist extension performed as a 2-count exercise to the rhythm of an audio-visual metronome set at 100. Each extremity performed 25 repetitive contractions unilaterally, commencing with the preferred hand. Thus every 30-sec. period of exercise was followed by a 30-sec. rest pause. When the load could no longer be lifted the requisite no. of times in the prescribed rhythm, the standard rest pause was allowed after which both hands exercised concurrently. The relation of the work done in the last unilateral bout of the failing side to the functional capacity in the first bilateral bout was accepted as the criterion in terms of which the effect of the procedure might be judged. Co-contraction of the dominant and failing hand indicates that bilateral exercise is significantly dynamogenic, increasing contractile power and endurance.