Control of Fingertip Forces in Young and Older Adults Pressing against Fixed Low- and High-Friction Surfaces
Figure 4
Summary data for electromyogram (EMG) activity during submaximal force-matching tasks.
Older adults had greater EMG activity than young adults for first dorsal interosseous (FDI) (A) and extensor digitorum communis (EDC) (B) while performing submaximal steadiness tasks. EMG activity also increased in EDC when pressing against a low-friction vs. high-friction surface, potentially to stabilize the fingertip while pressing against the slippery Teflon surface. In contrast to EDC, EMG amplitude also increased in FDI and flexor digitorum superficialis (FDS) while pressing at the 10% vs. 2.5% MVC force level. Thus, altered submaximal force fluctuations were accompanied by changes in muscle activation strategies by young and older adults. Values are means ± SE. ap<.001 vs. young adults; bp<.001 vs. 2.5 MVC force; cp = .002 vs. young adults; dp = .006 vs. high-friction surface.