Using a simple rope-pulley system that mechanically couples the arms, legs, and treadmill reduces the metabolic cost of walking.
Daisey Vega, Christopher J Arellano
PMID 34098979WHAT IT FOUND
Healthy walkers used a rope-pulley system linking arms to legs on a treadmill.
It did not assist leg swing as intended, but instead reduced net metabolic power by 17% by shifting propulsion demands from the legs to the whole body via the treadmill belt.
Key findings
01Walking with the arm-leg pulley system reduced net metabolic power by 17% compared to normal walking.
02The device did not reduce leg muscle activity during the swing phase, failing the primary hypothesis that arms would assist leg swing.
03The metabolic reduction occurred because the arms helped propel the whole body forward using energy from the treadmill belt, decreasing the legs' propulsive impulse by 43%.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
Read the rest of this summary
You get three full summaries a month, free, and we do not ask for a card. Search, the TL;DRs and your library stay unlimited either way.
What it does not show
The study was conducted only on eight healthy, young adults walking at a fast speed (1.25 m/s), so results may not apply to clinical populations with slower, impaired gait. The device failed to achieve its intended design goal of assisting leg swing; the metabolic benefit came from an unintended interaction with the treadmill belt. There is a risk that the device could disrupt balance or cause injury due to increased braking forces, which was not assessed in this healthy cohort. The sample size was smaller than planned (8 instead of 10) due to equipment malfunction.
Declared interests
Funded by the University of Houston. The authors declared no competing interests.
The easy way to misread this
Do not assume this device will help patients swing their legs more easily. The study found it did not reduce leg swing muscle activity; the metabolic benefit came from a different mechanism involving whole-body propulsion via the treadmill belt.