Quantification of the effects of instruction type, verbal encouragement, and visual feedback on static and peak handgrip strength

The purpose of the study was to quantify the magnitude of the influence of the effects of instruction type, verbal encouragement, and visual feedback on static strength and to verify the applicability of the Caldwell Regimen to grip strength measurement. Twenty-one male students participated in the study that employed an isokinetic wrist dynamometer to measure handgrip strength. The results revealed that these three factors had significant positive effects on static grip strength, peak grip strength and time to reach the maximal strength. The findings showed that when subjects were free to perform the handgrip any way they chose (free instruction (FI)), they most closely followed a fast contraction and maintained force (FCM). The strength results from the Caldwell Regimen were also similar to the FCM, but the variability during the exertion was higher with the Caldwell Regimen instructions of a slow contraction and maintain (SCM) than FCM. A modified Caldwell Regimen with a shorter maintained time rather than a long maintained time might allow a more stable "static" strength. In addition, the use of verbal encouragement and visual feedback should be noted, if employed in a strength test. Relevance to industry Handgrip strength is commonly used in industrial tasks. The maximum handgrip strength is often measured employing the Caldwell Regimen. This paper examines the static and peak handgrip strengths associated with the subject's preferred handgrip method other instruction types. It also examines the effect of visual feedback and verbal encouragement that are not often associated with industrial work, but are frequently used in strength testing.