Muscle strength rather than muscle mass is associated with standing balance in elderly outpatients

OBJECTIVES: Assessment of the association of muscle characteristics with standing balance is of special interest, as muscles are a target for potential intervention (ie, by strength training).

DESIGN: Cross-sectional study.

SETTING: Geriatric outpatient clinic.

PARTICIPANTS: The study included 197 community-dwelling elderly outpatients (78 men, 119 women; mean age 82 years).

MEASUREMENTS: Muscle characteristics included handgrip and knee extension strength, appendicular lean mass divided by height squared (ALM/height(2)), and lean mass as percentage of body mass. Two aspects of standing balance were assessed: the ability to maintain balance, and the quality of balance measured by Center of Pressure (CoP) movement during 10 seconds of side-by-side, semitandem, and tandem stance, with both eyes open and eyes closed. Logistic and linear regression models were adjusted for age, and additionally for height, body mass, cognitive function, and multimorbidity.

RESULTS: Handgrip and knee extension strength, adjusted for age, were positively related to the ability to maintain balance with eyes open in side-by-side (P = .011; P = .043), semitandem (P = .005; P = .021), and tandem stance (P = .012; P = .014), and with eyes closed in side-by-side (P = .004; P = .004) and semitandem stance (not significant; P = .046). Additional adjustments affected the results only slightly. ALM/height(2) and lean mass percentage were not associated with the ability to maintain standing balance, except for an association between ALM/height(2) and tandem stance with eyes open (P = .033) that disappeared after additional adjustments. Muscle characteristics were not associated with CoP movement.

CONCLUSION: Muscle strength rather than muscle mass was positively associated with the ability to maintain standing balance in elderly outpatients. Assessment of CoP movement was not of additional value.