251 Views

Aging Research & Geriatric Rehabilitation

Stretch-shortening cycle potentiation and rate of torque development of eccentric-preloaded-concentric torque is lower with aging

Unique joint and neuromuscular characteristics dictate loss of stretch-shortening cycle potentiation in older adults

Wednesday, November 9, 2022

1:11 PM – 1:16 PM

Location: Station 2

Presenting Author(s)

Phuong Quach, MPH

PhD Student in Rehabilitation Science
University of Alabama at Birmingham, United States

Non-presenting Author(s)

Gabrielle Richards

Student Physical Therapy
University of Alabama at Birmingham, United States
Harshvardhan Singh, PT, MS, PhD

Assistant Professor
University of Alabama at Birmingham
Birmingham, Alabama, United States

Research Objectives: To compare the rate of force development (RFD) and the stretch-shortening cycle (SSC) potentiation of eccentric-preloaded concentric contraction between young and older populations at 3 different velocities: 120°/s, 180°/s, and 240°/s for 3 different range of motions (ROMs): small (ROM for walking), medium, and large (ROM for balance recovery from moderate to severe large-intensity perturbations, respectively) at the ankle.

Design: Cross-sectional study

Setting: University laboratory

Participants: 23 participants (12 young adults and 11 older adults)

Interventions: Not applicable

Main Outcome Measures: Ankle plantarflexors were measured randomly for concentric only and eccentric-preloaded concentric muscle strength at 3 different velocities (120°/s, 180°/s, and 240°/s) at 3 different ROMs (small, medium, and large) on an isokinetic device. Body-mass normalized differences between eccentric-preloaded concentric torque and concentric torque without any preloading was calculated as SSCpotentiation. Average RFD (slope of eccentric-preloaded maximum concentric torque-time curve) was calculated for all the conditions in young and older adults.

Results: SSCpotentiation at the ankle in older adults was lower than young adults at 120°/s for the middle ROM (p ≤ 0.05, d = 0.3), and at 240°/s for the large ROM (p = 0.035, d = 0.3). Older adults had significantly lower RFD of eccentric-preloaded concentric torque at the ankle at 120°/s and 240°/s (p ≤ 0.05, d = 0.8 - 1.8) for the middle ROM, and at 120°/s, and 180°/s for the large ROM (p < 0.05, d = 1.0 - 2.6) than young.

Conclusions: SSCpotentiation and RFD of eccentric-preloaded concentric torque at the ankle are lower in older adults than young adults. The degree of deficit of RFD is markedly higher than SSCpotentiation in older adults. Whether these deficits with aging explain a greater risk of mobility-loss and falls remains unknown.

Author(s) Disclosures: No conflict of interest

Learning Objectives:

Compare movement velocity-specific differences at different ranges at the ankle in rate of force development of eccentric-preloaded concentric torque between young and older adults.
Compare movement velocity-specific differences at different ranges at the ankle in the stretch-shortening cycle potentiation between young and older adults.
Understand movement velocity-specific relationship between stretch-shortening cycle potentiation and rate of force development at different ranges.
Compare range of movement-specific differences in the stretch-shortening cycle potentiation between young and older adults.