Table 1.

Measures of physical function and strength^a

Physical function & strength	Description
Six Minute Walk Test (6MWT)	Assesses the self-paced distance walked over 6 minutes and provides an objective evaluation of submaximal aerobic and functional capacity (25). Participants walked around a 40m rectangular track within an enclosed corridor. As most activities-of- daily-living are performed at submaximal levels of exertion, the 6MWT better reflects the functional capacity for daily physical activities than other walk tests (26).
Chair Sit-and-Reach Test (CSR)	Provides a valid and reliable measure of hamstring flexibility in older adult (27). While sited on a chair, participants would attempt to touch the toes of their leg (heel on floor and foot dorsiflexed), by slowly bending forward at the hip. A static position was held for 2s and the distance between the middle finger tip and middle of the toe (representing a “zero score”) was measured. Reaches short of the toe were recorded as negative scores, while reaches beyond the toes were recorded as positive scores. The best score of 2 trials was recorded as the final score.
Short Physical Performance Battery (SPPB)	Comprising a battery of three tests, the SPPB provides an objective assessment of lower extremity function in older persons and has been shown to be a reliable predictor of disability, institutionalization and mortality in older persons (28). The standing balance test required participants to maintain a side-by-side, semi-tandem and tandem stance for 10s each. Repeated chair stands involved participants standing up from a chair and sitting down again, as quickly as possible, without the use of their arms, for five repetitions. Gait speed was assessed by the fastest time of two 3m usual-pace, walk attempts. Results of each test were scored on a 5-level categorical scale: zero represented inability to complete the test and 4 represented the highest level of performance. A summary performance SPPB score, reflecting the functional status of participants in this study, was created by summing the categorical rankings of performance on the 3 tests.
Muscle Strength	Upper extremity muscle strength was assessed by measuring maximum hand-grip using a hand-held dynamometer (T.K.K. 5401 Grip D; Takei Scientific, Nigata, Japan). Lower extremity muscle strength was assessed by measuring knee-extension strength using a universal shear beam load cell with digital transducer (LCC 500; Omega, Stanford, CT). Three trials were performed for both measurements and the maximum score achieved was recorded.
Specific Strength (muscle quality)	Upper extremity specific strength was assessed as the ratio of hand grip strength (kg) to arm lean mass (kg), determined by DXA. Lower extremity specific strength was calculated as the ratio of knee extension strength (kg) to tSM (L), determined by MRI.

Note: DXA, Dual energy x-ray absorptiometry; MRI, Magnetic resonance imaging; tSM, thigh skeletal muscle;

^aStandardized procedures and instructions were administered. Participants were asked to refrain from consuming caffeine, alcohol or a heavy meal at least 2h before testing and to avoid all strenuous physical exercise in the preceding 24h.