Adaptations in Reactive Balance Strategies in Healthy Older Adults After a 3-Week Perturbation Training Program and After a 12-Week Resistance Training Program

Abstract

Both resistance training (RT) and perturbation-based training (PBT) have been proposed and applied as interventions to improve reactive balance performance in older adults. PBT is a promising approach but the adaptations in underlying balance-correcting mechanisms through which PBT improves reactive balance performance are not well-understood. Besides it is unclear whether PBT induces adaptations that generalize to movement tasks that were not part of the training and whether those potential improvements would be larger than improvements induced by RT. We performed two training interventions with two groups of healthy older adults: a traditional 12-week RT program and a 3-week PBT program consisting of support-surface perturbations of standing balance. Reactive balance performance during standing and walking as well as a set of neuro-muscular properties to quantify muscle strength, sensory and motor acuity, were assessed pre- and post-intervention. We found that both PBT and RT induced training specific improvements, i.e., standing PBT improved reactive balance during perturbed standing and RT increased strength, but neither intervention affected reactive balance performance during perturbed treadmill walking. Analysis of the reliance on different balance-correcting strategies indicated that specific improvements in the PBT group during reactive standing balance were due to adaptations in the stepping threshold. Our findings indicate that the strong specificity of PBT can present a challenge to transfer improvements to fall prevention and should be considered in the design of an intervention. Next, we found that lack of improvement in muscle strength did not limit improving reactive balance in healthy older adults. For improving our understanding of generalizability of specific PBT in future research, we suggest performing an analysis of the reliance on the different balance-correcting strategies during both the training and assessment tasks.

Comparing the Effects of Two Perturbation-Based Balance Training Paradigms in Fall-Prone Older Adults: A Randomized Controlled Trial

“…Furthermore, our results demonstrate limited transfer of different reactive paradigms. These findings are in accordance with previous studies that showed that reactive balance tasks were not necessarily improved if they differed from the trained paradigm [13, 43].…”

“…In addition, exercising walking might also improve leg strength [48]. However, some other PBT studies did not find effects on muscle strength in healthy older adults [12, 18, 36, 43], but these either included only static perturbation training or only a small amount of training sessions. The descriptive leg strength improvements in PBT stability of 5% lay in between the results of previous studies investigating the same training paradigm in healthy older adults that found improvements of 3–11% in knee extension strength capacity [14, 16].…”

Prognostic accuracy of the one-legged balance test in predicting falls: 15-years of midlife follow-up in a British birth cohort study

“…This is concerning for ongoing translation, given that a population-level association does not necessarily equate with prediction at an individual level ( 15 – 17 ). Although successful balance strategies that involve proactive or reactive adaptations are directly involved in avoiding a fall ( 18 – 20 ), there is insufficient investigation as to whether poor one-legged balance performance predicts subsequent falls and what constitutes the threshold for a positive screening result ( 7 ).…”