Frequent alternate muscle activity of plantar flexor synergists and muscle endurance during low-level static contractions as a function of ankle position

Table 1 Force and electromyographic parameters at 10 and 100% of maximal voluntary contraction

Force and electromyographic parameters	Ankle joint angle
Force and electromyographic parameters	90°	100°	110°	120°	130°
At MVC
Force (N)	1220.4 ± 162.6 a,b	1226.1 ± 160.4 a,b	936.8 ± 142.0 a	664.3 ± 173.1	486.1 ± 101.8
Average rsEMG (μV)
Lateral gastrocnemius (LG)	89.3 ± 37.7 c,d	109.4 ± 43.4	112.6 ± 43.9	108.9 ± 41.6	110.4 ± 44.6
Medial gastrocnemius (MG)	151.3 ± 48.8 a,b,c	171.1 ± 42.2	170.8 ± 39.3	169.0 ± 47.9	175.8 ± 51.3
Soleus muscle (Sol)	109.9 ± 32.9 a,b	95.4 ± 27.4 a	86.9 ± 32.3	84.2 ± 37.8	75.5 ± 32.9
At 10% MVC
Target force (N)	122.0 ± 16.3 a,b	122.6 ± 16.0 a,b	93.7 ± 14.2 a	66.4 ± 17.3	48.6 ± 10.2
%EMG_max (%)
LG	0.0 ± 0.0 a	0.0 ± 0.1 a	0.0 ± 0.1 a	0.2 ± 0.2 a	4.3 ± 4.9
MG	6.1 ± 6.5 a,b	6.0 ± 5.3 a,b	9.8 ± 5.4 a	15.1 ± 8.7	19.1 ± 12.6
Sol	8.6 ± 4.2	14.9 ± 4.4 a	11.9 ± 5.2	8.7 ± 6.0	7.6 ± 4.4

MVC Maximal voluntary contraction, rsEMG raw electromyogram (EMG) signals that had been amplified, full-wave rectified, and smoothed (time constant 300 ms), %EMG_max amplitude of rsEMG obtained at each angle normalized according to the value of the EMG amplitude at MVC
Values are presented as the mean ± standard deviation (SD)
Values followed by a, b, c, and d are significant different from values at 130°, 120°, 110°, and 100°, respectively

ISSN: 1880-6562