| Description |
Asymmetries in movement and muscle function are ubiquitous and long lasting in those who survive after hip fracture. Enduring asymmetries in lower limb muscle function (i.e., strength and power) have been associated with fall frequency and impaired physical mobility among older adults. Lower limb discrepancies in vertical ground reaction forces (vGRFs) are evident during performance of mobility tasks, including ambulation and transfers from a seated to a standing position. Movement asymmetry during a sit-to-stand task (STST) made a small, independent contribution (r2 = 7%) to stair climb test performance when coupled with gait speed (r2 = 41%), balance confidence (r2 = 4%), and self-reported function (r2 = 4%); while STST asymmetry did not independently predict modified physical performance test score. To date, there is no specific rehabilitation strategy to restore movement pattern and muscle function symmetry after hip fracture. Thus, the potential impact of specific strategies to improve symmetry in vGRF variables during STST performance, and muscle function after hip fracture is unclear. We examined the feasibility and beneficence of High Intensity Task-Oriented strategies designed to improve Strength and Symmetry (HI-TOSS). We determined that asymmetries in strength, power, and vGRFs evident during STST, were each significantly reduced (i.e., improved) with training. Finally, improvements in muscle quality and its components with training after hip fracture have not been tested. We identify the surgical limb to be 10%-15% lower in muscle mass and muscle quality compared to the nonsurgical limb after discharge from usual care. Following HI-TOSS, muscle mass in the surgical limb improved by 9%, muscle strength improved by 21%, and muscle quality improved by 14%. Expectedly, physical performance improved significantly with training (~20% improvement); exceeding established clinically meaningful difference values. In summary, specific strategies to reduce asymmetries in movement and improve muscle function are well-tolerated in community-dwelling older adults after hip fracture and can yield improvements in STST and muscle function symmetry. Substantial improvements in STST performance, muscle function, muscle composition, and physical function are expected with HI-TOSS. Further studies should determine long-term effects and optimal HI-TOSS implementation practices in a restorative effort to enhance recovery after hip fracture. |
