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

PURPOSE: 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.

METHOD: This quantitative correlation study recruited a convenience sample of 105 healthy participants through community and university flyers. Participants were evaluated with the BTE grip tool for a power strength assessment through full bilateral grasp ROM, and at 50% resistive force of their baseline maximum static strength value. The Jebsen Hand Function Test provided comparative hand function results for the age decade divided participant groups for correlation statistical analysis of mean values for both tests.

RESULTS: Based on ANOVA 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, before decline between 40-49 years. Peak hand function occurred in those 40-49 with the dominant hand and 50-59 in non-dominant hands.Twenty to 29 year-olds had the slowest Jebsen time scores of any age group. Statistical analysis confirmed there was no relationship between occupational classification categories and hand function or strength, except in the strength values of those who perform “heavy” work.

CONCLUSION: 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. In full scale comparative analysis of all age groups, hand function did not decrease until the sixth decade. After the age of 39, a linear decline of dynamic grip strength in the dominant hand was evident. The poor hand function scores in the 20-29 year age group was directly related to poor handwriting timed subtest scores. With removal of the handwriting subtest results and re-calculation of all group scores, hand function results then revealed a decline in hand function for those in the 30-39 year age group. The Jebsen Hand function test may unfairly bias the results of younger clients due to a timed writing evaluation.

This study impacts current evidence-based clinical practice by confirming that no correlation exists between static or dynamic strength results in either hand with hand function for intervention planning purposes. There is a decline in both hand strength and hand function after the age of 39 when a handwriting assessment is not a factor in overall test results. It is vital to use current, population applicable 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. doi: 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. doi: 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. doi: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. doi: 10.1177/175899830501000101