Effect of force adjustment modalities on characteristics for force generation and relaxation

Abstract

BACKGROUND: The systematic characteristics of force generation and relaxation have been investigated using a graded isometric task for several target levels and magnitudes in the upper and lower limb. However, whether a relaxation modality affects the accuracy or speed of grading remains unclear. In addition, speed characteristics are still unclear in both force generation and relaxation modalities. OBJECTIVE: To investigate the effect of force adjustment modalities on force generation and relaxation characteristics. METHODS: Participants were instructed to match a target force level as quickly and as accurately as possible under peak and keep adjustment modalities. The force generation task was increased from 10% to 30%, 50%, and 70% of the maximum voluntary force (MVF). The force relaxation task was decreased from 70% to 50%, 30%, and 10% MVF. The recorded force was analyzed. Errors in reproduction were computed in both modalities and target levels of force. RESULTS: The errors of the peak adjustment modality were greater than those of the keep adjustment modality in both tasks. The reaction time was longer with the peak adjustment modality than with the keep adjustment modality in both tasks. CONCLUSION: Speed was affected by the choice of adjustment modality.