Is There a Relationship Between Dynamic Grip Strength and Hand Function in Healthy Adults?

In occupational therapy, the primary goal is to maximize an individual's functional independence in meaningful daily occupations. Hand function plays a vital role in occupational performance. Static grip strength measurements have not predicted hand function in self-reported or timed assessments of hand function (Cox, Spalding, & Kramer, 2006; Liu, Fredrick, Betram, Utley, & Fess, 2017; Tyler, Adams, & Ellis, 2005). Relatively few studies have sought to determine if a correlation exists between dynamic hand strength and the inherently dynamic use of the hand for occupations. Lastayo and Hartzel (1999) concluded dynamic measurements were a better indicator of a person’s functional capabilities, due to the dynamic nature of occupations and the overestimation of static grip values over actual dynamic strength values in functional tasks. The purpose of this quantitative research was to determine if a correlation existed between dynamic grip strength and hand function through the aging process, at a defining point, & whether reported occupational classification influenced the results. Research results add to the body of evidence regarding the use of static vs. dynamic grip strength results and functional assessments across the age continuum for intervention selection in those with hand dysfunction. This quantitative correlation study recruited a convenience sample of 105 healthy participants aged 21-67, who were divided into decade age groups for comparative correlation statistical analysis of mean values for dynamic grip strength and hand function. Participants were evaluated using the Baltimore Therapeutic Equipment grip tool for a power strength assessment through full bilateral grasp range of motion and the Jebsen Hand Function Test was selected to provide age related comparative hand function values. Based on ANOVAs and LSD Post Hoc tests, there was an insufficient correlation between dynamic grip strength and hand function in both dominant (0.126) and non-dominant hands (0.034) for all age groups. Hand strength peaked between 30-39 years for dominant and non-dominant hands, before a linear decline in the dominant hand. Initial peak hand function occurred in those 40-49 with the dominant hand and 50-59 in the non-dominant hand. Those 20-29 years old had the slowest Jebsen Hand Function time scores of any age group. Statistical analysis confirmed there was no relationship between reported level of work and hand function or hand strength, except in the strength values of those who perform ‘heavy’ work. The correlation between hand function and dynamic hand strength is not strong enough to use strength as a basis for clinical reasoning of client function for intervention planning. Hand strength and hand function do not decline at the same rate through the aging process. Poor hand function scores for those in the 20-29 year age group were directly related to poor handwriting timed subtest scores. With removal of the handwriting subtest results and re-calculation of all group hand function scores, the decline in hand function became evident for those in the 30-39 year age group as opposed to a peak after 40 with the included handwriting subtest. This change in results indicates that the Jebsen Hand Function test may unfairly bias younger clients due to a timed writing evaluation. This study impacts current evidence-based practice by confirming that no correlation exists between either static or dynamic hand strength in either hand with hand function at any stage during the lifespan. There is a decline in both hand strength and hand function after the age of 39, if a handwriting assessment is not included in hand function testing. It is vital to use current, population specific assessments for intervention planning.

References

Cox, J., Spaulding, & S. Kramer, J. (2006). Is there a relationship between hand strength and hand function? Journal of Hand Therapy, 19(4), 444-445. https://doi.org/10.1197/j.ht.2006.07.011

Lastayo, P., & Hartzel, J. (1999). Dynamic versus static grip strength: How grip strength changes when the wrist is moved, and why dynamic grip strength may be a more functional measurement. Journal of Hand Therapy, 12(3), 212–218. https://doi.org/10.1016/S0894-1130(99)80048-9

Liu, C., Marie, D., Fredrick, A., Betram, J., Utley, K., & Fess, E. (2017). Predicting hand function in older adults: evaluations of grip strength, arm curl strength, and manual dexterity. Aging Clin Exp Res, 29, 753-760. https://doi.org/10.1007/s40520-016-0628-0

Tyler, H., Adams, J., & Ellis, B. (2005). What can handgrip strength tell the therapist about hand function? British Journal of Hand Therapy, 10, 4-9. https://doi.org/10.1177/175899830501000101