Lower extremity strength and power asymmetry assessment in healthy and mobility-limited populations: reliability and association with physical functioning.
OBJECTIVE
This study assessed the reliability of evaluating asymmetrical strength and power deficits in the lower limbs of healthy middle-aged, healthy older and mobility-limited elders. We also explored the relationship between limb asymmetry and physical functioning.


METHODS
We evaluated baseline knee extension strength and power asymmetry data from a cohort of older adults (n=57; 74.2±0.9 yrs, 26 male) who participated in a lower body strength training study (TS) and from a cross-sectional study of community dwelling volunteers. Cross-sectional participants were recruited into: healthy middle-aged (MH) (n=31; 47.4±4.8 yrs, 14 male), healthy older (OH) (n=28; 74.0±3.6 yrs, 16 male) and mobility-limited older (OML) (n=34; 77.8±4.5 yrs, 16 male) groups. Knee extensor strength (1RM) and power asymmetry at 40% and 70% of 1RM were evaluated for test-retest reliability using intraclass correlation coefficients (ICCs).


RESULTS
Knee extension 1RM, and peak power at 40% and 70% asymmetry ICCs exhibited excellent to good reliability in the TS and OML groups (TS= 0.8, 0.7 and 0.7, respectively; OML= 0.7, 0.7, and 0.9, respectively) but not in the MH and OH groups. No consistent association between lower limb asymmetry and measures of physical functioning was observed.


CONCLUSIONS
Assessment of lower limb strength and power asymmetry is more reliable in mobility-limited elders when compared to healthy middle-aged and older subjects. The relationship of lower limb asymmetry to physical functioning is poor, in contrast to associations between the absolute strength and power of the individual limbs and physical functioning.
Carabello
Robert J
RJ
Tufts University, Boston, MA 02111, USA.
Reid
Kieran F
KF
Clark
David J
DJ
Phillips
Edward M
EM
Fielding
Roger A
RA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D007866:Leg / Q000473:pathology / Q000502:physiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D051346:Mobility Limitation; D053580:Muscle Strength; D010809:Physical Fitness; D015203:Reproducibility of Results; D055070:Resistance Training