Table 2.

Force steadiness and EMG amplitude during steady contractions with wrist extensors at 10% MVC force performed before and after practicing the wrist-extension task

	Middle-Aged Adults		Older Adults
	Before	After	Before	After
CV for force, %	1.47 ± 0.69	1.38 ± 0.74	1.53 ± 0.45	1.64 ± 0.63
	[1.15, 1.78]	[1.04, 1.71]	[1.32, 1.74]	[1.34, 1.95]
Wrist extensors, mV	2.48 ± 0.83	2.76 ± 0.92*	2.81 ± 0.95	2.98 ± 0.97*
	[2.09, 2.86]	[2.33, 3.19]	[2.37, 3.26]	[2.50, 3.46]
Wrist flexors, mV	1.55 ± 0.63	1.56 ± 0.69	1.77 ± 0.74	1.66 ± 0.59
	[1.25, 1.84]	[1.26, 1.85]	[1.43, 2.12]	[1.38, 1.97]
Coactivation index, %	62.2 ± 4.1	64.4 ± 4.1*	62.1 ± 4.7	64.2 ± 5.1*
	[60.3, 64.1]	[62.5, 66.3]	[59.9, 64.3]	[61.7, 66.8]

Values are means ± SD [95% confidence interval]. Electromyography (EMG) amplitude (mV) was calculated as the sum of the monopolar recordings with the high-density electrodes. CV, coefficient of variation; MVC, maximum voluntary contraction.

^*P ≤ 0.0206 relative to before.