Age-related differences in lower extremity power after support surface perturbations.

Area of Science:

• Biomechanics
• Motor Control
• Gerontology

Background:

• Balance recovery is crucial for preventing falls, especially in older adults.
• Understanding the mechanical underpinnings of balance responses is key to developing effective interventions.

Purpose of the Study:

• To investigate age-related differences in the ability to generate, absorb, and transfer mechanical energy during balance recovery.
• To determine if these differences explain the shift from feet-in-place to compensatory stepping responses.

Main Methods:

• A cross-sectional study involving younger (18-35 years) and older (65-85 years) women.
• Participants experienced forward and backward support surface translations.
• Lower extremity joint and muscle power were analyzed during feet-in-place and stepping responses.

Main Results:

• Older adults demonstrated significantly less muscle power absorption after backward perturbations compared to younger adults.
• Response type (feet-in-place vs. step) significantly affected joint power in both forward and backward perturbations.
• Muscle power was significantly affected by response type only in the forward perturbation condition.

Conclusions:

• The compensatory step is energetically less demanding than the feet-in-place response.
• Reduced muscle energy absorption in older adults contributes to their reliance on compensatory stepping.
• Proximal (hip/knee) musculature plays a more critical role in energy absorption than distal (ankle) musculature during balance recovery.