The purpose of this investigation was to determine whether increases in internal (muscular) demand would be proportional to increases in the external demand during heel-raise exercise. Seven male (mean age 74.9 ± 4.8 years) and 9 female (mean age 74.4 ± 5.1 years) older adults performed both double-leg heel raises and single-leg heel raises under 3 loading conditions (no external resistance and +5% and +10% of each participant’s body weight). Kinematic and kinetic dependent variables were calculated using standard inverse-dynamics techniques. The results suggest that although the single-heel raise led to increases in peak net joint moments, power, and mechanical-energy expenditure (MEE), it did so at the expense of range of motion and angular velocity. In addition, increasing the external resistance by 5% of participants’ body weight did not elicit significant changes in either the power or the MEE of the ankle joint. These effects should be considered when prescribing these exercises to older adults.
Flanagan is with the Dept. of Kinesiology, California State University, Northridge, CA 91330-8287. Song and Salem are with the Dept. of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA, 90033. Wang is with the School of Physical Therapy, National Cheng Kung University, 701 Tainan, Taiwan. Greendale is with the David Geffen School of Medicine, Division of Geriatrics, UCLA, Los Angeles, CA 90015-1687. Azen is with the Keck School of Medicine, Dept. of Preventive Medicine, University of Southern California, Los Angeles, CA 90033.