Data from: Differential changes with age in multiscale entropy of electromyography signals from leg muscles during treadmill walking

Age-related gait changes may be due to the loss of complexity in the
neuromuscular system. This theory is disputed due to inconsistent results
from single-scale analyses. Also, behavioral adaptations may confound
these changes. We examined whether EMG dynamics during gait is less
complex in older adults over a range of timescales using the multiscale
entropy method, and whether slower walking attenuates this effect. Surface
EMG was measured from the left vastus lateralis (VL), biceps femoris (BF),
gastrocnemius (GA), and tibialis anterior (TA) in 17 young and 18 older
adults as they walked on a treadmill for 5 minutes at 0.8x-1.2x of
preferred speed. Sample entropy (SE) and the complexity index (CI) of the
EMG signals were calculated after successive coarse-graining to extract
dynamics at timescales of 27 to 270 Hz, with m = 2 and r = 0.15 SD. SE and
CI were lower across the timescales in older adults in VL and BF, but
higher in GA (all p<0.001); these results held for VL and GA even
after accounting for longer EMG burst durations in older adults. CI was
higher during slower walking speed in VL and BF (p<0.001). Results
were mostly similar for m = 3 and r = 0.01–0.35. Smaller r was more
sensitive to age-related differences. The decrease in complexity with
aging in the timescales studied was limited to proximal muscles,
particularly VL. The increase in GA may be driven by other factors.
Walking slower may reflect a behavioral adaptation that allows the nervous
system to function with greater complexity.