Normative data for isometric strength of 8 different muscle groups and their usefulness as a predictor of loss of autonomy among physically active nursing home residents: the SENIOR cohort

OBJECTIVES: To provide normative values for isometric strength of 8 different muscle groups among nursing home residents and to investigate their predictive value for the decline of autonomy. METHODS: This is an analysis of the 1-year follow-up of the SENIOR cohort. At baseline, isometric muscle strength of residents has been assessed for 8 muscle groups using the MicroFET2. The cut-off threshold for low relative isometric muscle strength was defined as the lower quartile. The outcome was the 1-year loss of autonomy (i.e. a decrease of ≥1 point on the ADL scale between baseline and 12-month follow-up). Logistic regressions were carried out to assess the predictive value of isometric muscle strength for the loss of autonomy. RESULTS: 204 subjects (83.2±8.99 years, 72.5% women) were included. Threshold values of isometric strength were: knee flexors=0.94, knee extensors=1.07, ankle flexors=0.77, ankle extensors=0.88, hip abductors=0.78, hip extensors=0.79, elbow flexors=0.99 and elbow extensors= 0.71 N/kg. After adjustment for age and sex, the cut-off values for knee extensors (p=0.04) and for ankle extensors (p=0.03) were significantly predictive of loss of autonomy. CONCLUSIONS: The normative values for knee extensors and ankle extensors are independent predictors for loss of autonomy.