Patterns of whole-body muscle activations following vertical perturbations during standing and walking.
Desiderio Cano Porras, Jesse V Jacobs, Rivka Inzelberg and 3 others
PMID 33957953WHAT IT FOUND
Vertical balance perturbations activated thigh muscles early, while horizontal perturbations activated lower-leg muscles first.
During walking, downward perturbations activated the opposite-side shoulder muscle early. Visual conflict delayed responses, and eyes closed increased muscle activation duration and magnitude.
Key findings
01During standing, vertical perturbations activated proximal leg muscles first, while horizontal perturbations activated distal leg muscles first.
02During walking, downward perturbations activated the opposite-side shoulder muscle earlier than the same-side shoulder muscle, and opposite-side trunk and shoulder muscles were among the first to respond.
03During standing physical perturbations, static-camera conditions delayed response timing, while eyes-closed conditions increased activation duration and magnitude.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Fourteen young, healthy adults only, so results may not apply to older adults, people with neurological conditions, or patients with balance disorders. Perturbations were controlled and participants knew a perturbation was coming, so responses may not reflect truly unexpected real-world losses of balance. Standing perturbations were slow enough to avoid stepping, so they may not match faster perturbations that cause stepping or falls. The study measured muscle activation patterns, not clinical outcomes such as falls, function, or treatment benefit. One participant had a treadmill speed limit due to technical constraints, although their balance performance was reported as similar to other occasions. Visual-only perturbations did not produce responses in all exposures, and some people may be insensitive to visual perturbations.
Declared interests
Funding was provided by Horizon 2020 and the Ministry of Science and Technology, Israel. The supplied text gives no separate author conflict-of-interest declaration.
The easy way to misread this
Do not conclude that perturbation training prevents falls or improves balance in patients. This study measured muscle activation in 14 young healthy adults, not clinical outcomes, and the perturbations were partly expected.