Grip strength cut-points from the Swiss DO-HEALTH population

Background: While grip strength (GS) is commonly assessed using a Dynamometer, the Martin Vigorimeter was proposed as an alternative method especially in older adults. However, its reference values for Swiss older adults are missing. We therefore aimed to derive sex- and age-specific GS cut-points for the dominant and non-dominant hand (DH; NDH) using the Martin Vigorimeter. Additionally, we aimed to identify clinically relevant weakness and assess convergent validity with key markers of physical function and sarcopenia in generally healthy Swiss older adults.

Methods: This cross-sectional analysis includes baseline data from Swiss participants enrolled in DO-HEALTH, a 3-year randomized controlled trial in community-dwelling adults age 70 + . For both DH and NDH, 4 different definitions of weakness to derive GS cut-points by sex and age category (≤ 75 vs. > 75 years) were used: i) GS below the median of the 1^st quintile, ii) GS below the upper limit of the 1^st quintile, iii) GS below 2-standard deviation (SD) of the sex- and age-specific mean in DO-HEALTH Swiss healthy agers (i.e. individuals without major chronic diseases, disabilities, cognitive impairment or mental health issues) and iv) GS below 2.5-SD of the sex- and age-specific mean in DO-HEALTH Swiss healthy agers. To assess the proposed cut-points' convergent validity, we assessed their association with gait speed, time to complete the 5 Times Sit-To-Stand (5TSTS) test, and present sarcopenia.

Results: In total, 976 participants had available GS at the DH (mean age 75.2, 62% women). According to the 4 weakness definitions, GS cut-points at the DH ranged from 29-42 and 25-39 kPa in younger and older women respectively, and from 51-69 and 31-50 kPa in younger and older men respectively. Overall, weakness prevalence ranged from 2.0% to 19.3%. Definitions of weakness using the median and the upper limit of the 1^st GS quintile were most consistently associated with markers of physical performance. Weak participants were more likely to have lower gait speed, longer time to complete the 5TSTS, and sarcopenia, compared to participants without weakness.

Conclusions: In generally healthy Swiss older adults, weakness defined by the median or the upper limit of the 1^st GS quintile may serve as reference to identify clinically relevant weakness. Additional research is needed in less healthy populations in order to derive representative population-based cut-points.

Trial registration: ClinicalTrials.gov Identifier: NCT01745263.