Passive-elastic knee-ankle exoskeleton reduces the metabolic cost of walking.

Only eight healthy adults were tested, so the results do not show what would happen in people with walking disability. The device was tested at one speed, 1.25 m/s, on a treadmill, not in everyday walking. The exoskeleton added about 1.4 kg to each leg and changed stride length, contact time, and step width, so the comparison with no exoskeleton included these changes as well as any assistance. The researchers did not measure lower limb segment kinematics or kinetics during the experimental trials. Only the shank braces could be adjusted, and the ankle rope was not well aligned, which may have caused energy loss. A 21-minute adaptation period may not have been enough to account for learning or fatigue effects.

The funding section names Ministero dell’Istruzione, dell’Università e della Ricerca. No author conflicts are listed.

Do not conclude from the title that this exoskeleton makes walking less effortful than no device. In eight healthy adults, the best exoskeleton condition increased net metabolic power by 23% compared with walking without the exoskeleton, even though it was 10.7% lower than the same exoskeleton with springs disengaged.