ISCD, 2012;
Muscle Function, but Not Muscle Mass, is Related to Balance Confidence in Older Adults
Year: 2012
Buehring B, Fidler E, Libber J, Krueger D, Binkley N
University of Wisconsin Osteoporosis Clinical Center and Research Program, Madison , WI
Abstract
Background:Both impaired muscle function and low muscle mass are included in recent consensus sarcopenia definitions. Sarcopenia is associated with increased risk of falls and fear of falling. Self-reported health is a falls risk factor that predicts hip fracture. However, how
self-reported balance confidence relates to objective measures of muscle function and mass has received only limited evaluation. As such, this study examined the relationship of balance confidence with jumping mechanography (JM) parameters, classical muscle function tests and appendicular lean mass (ALM) as measured by DXA.
Methods:
Community dwelling individuals age 70+ completed the Activities-specific Balance Confidence (ABC) scale to assess balance confidence. This scale is reliable and able to distinguish fallers from non-fallers. Additionally, all volunteers performed several muscle
function tests including the short physical performance battery (SPPB), grip strength and JM. JM assesses muscle function using countermovement jumps to calculate body weight corrected peak power and jump height. Total body DXA was used to assess ALM. Statistical
testing included correlation of ABC scores with muscle function tests and ALM/height2. Based on their ABC score, participants were divided into groups of high, moderate and low balance confidence. Receiver-Operator Curves (ROC) and their area under curve (AUC) for the three defined confidence groups were calculated for the different muscle parameters.
Results: 97 individuals (49 females and 48 males, mean age 80.7, range 70 – 95 years) with and without osteoporosis and sarcopenia were studied. Participants had high balance confidence with only 10 individuals having ABC scores in the moderate range and none in the low range. Correlations from various regression analyses were statistically
significant (p < 0.05) but small and ranged from 0.05 for grip strength to 0.28 for total SPPB score. ALM/height2 was not associated with ABC score. ROC analysis revealed highest AUCs for gait speed and total SPPB score (~0.83). Jump power/height and chair rise time had lower AUCs (~0.75).
Conclusion:
Tests of muscle function, including JM, but not simple lean mass measurement, are associated with balance confidence. These data support the need to include both measures of muscle mass and muscle “quality” in clinical definitions of sarcopenia. This study is limited by the generally high balance confidence in the study cohort. Further studies are
needed to develop a sarcopenia test battery that is able to identify individuals at high falls risk. Subsequent implementation of such a testing approach may well increase accuracy of fracture estimation.
GID: 3006; Last update: 22.06.2012
