Differences in lower-extremity muscular activation during walking between healthy older and young adults

Schmitz, Anne; Silder, Amy; Heiderscheit, Bryan; Mahoney, Jane; Thelen, Darryl G.

doi:10.1016/j.jelekin.2008.10.008

« Previous Next »Journal of Electromyography and Kinesiology
Volume 19, Issue 6 , Pages 1085-1091, December 2009

Differences in lower-extremity muscular activation during walking between healthy older and young adults

Anne Schmitz
- Department of Biomedical Engineering, University of Wisconsin-Madison, 3039 Mechanical Engineering Building, 1513 University Ave., Madison, WI 53706, USA
Amy Silder
- Department of Biomedical Engineering, University of Wisconsin-Madison, 3039 Mechanical Engineering Building, 1513 University Ave., Madison, WI 53706, USA
Bryan Heiderscheit
- Department of Biomedical Engineering, University of Wisconsin-Madison, 3039 Mechanical Engineering Building, 1513 University Ave., Madison, WI 53706, USA
- Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, 3039 Mechanical Engineering Building, 1513 University Ave., Madison, WI 53706, USA
Jane Mahoney
- Department of Medicine, University of Wisconsin-Madison, 2870 University Ave., Suite 106, Madison, WI 53705, USA
Darryl G. Thelen
- Department of Biomedical Engineering, University of Wisconsin-Madison, 3039 Mechanical Engineering Building, 1513 University Ave., Madison, WI 53706, USA
- Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, 3039 Mechanical Engineering Building, 1513 University Ave., Madison, WI 53706, USA
- Department of Mechanical Engineering, University of Wisconsin-Madison, 3039 Mechanical Engineering Building, 1513 University Ave., Madison, WI 53706, USA
- Corresponding author. Address: Department of Mechanical Engineering, University of Wisconsin-Madison, 3039 Mechanical Engineering Building, 1513 University Ave., Madison, WI 53706, USA. Tel.: +1 608 262 1902; fax: +1 608 265 2316.

Received 16 May 2008; received in revised form 5 September 2008; accepted 7 October 2008. published online 11 December 2008.

Abstract

Previous studies have identified differences in gait kinetics between healthy older and young adults. However, the underlying factors that cause these changes are not well understood. The objective of this study was to assess the effects of age and speed on the activation of lower-extremity muscles during human walking. We recorded electromyography (EMG) signals of the soleus, gastrocnemius, biceps femoris, medial hamstrings, tibialis anterior, vastus lateralis, and rectus femoris as healthy young and older adults walked over ground at slow, preferred and fast walking speeds. Nineteen healthy older adults (age, 73±5 years) and 18 healthy young adults (age, 26±3 years) participated. Rectified EMG signals were normalized to mean activities over a gait cycle at the preferred speed, allowing for an assessment of how the activity was distributed over the gait cycle and modulated with speed. Compared to the young adults, the older adults exhibited greater activation of the tibialis anterior and soleus during mid-stance at all walking speeds and greater activation of the vastus lateralis and medial hamstrings during loading and mid-stance at the fast walking speed, suggesting increased coactivation across the ankle and knee. In addition, older adults depend less on soleus muscle activation to push off at faster walking speeds. We conclude that age-related changes in neuromuscular activity reflect a strategy of stiffening the limb during single support and likely contribute to reduced push off power at fast walking speeds.