Age-related changes in the activation timing of postural muscles to the prime mover muscle for bilateral arm flexion during standing

Table 2 Starting time of the postural muscles in each age groups

Groups	RA (ms)	ES (ms)	RF (ms)	BF (ms)	TA (ms)	GcM (ms)	SOL (ms)
Groups	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)
3–4 years	37.89 (20.99)†	1.88 (23.72)#	37.70 (33.12)†	41.40 (22.20)# †	6.46 (38.55)	46.40 (23.81)†	55.22 (20.87)†
5–6 years	33.94 (25.94)†	−7.45 (16.23)#†	42.88 (34.09)†	37.90 (25.82)#†	8.72 (37.22)	46.60 (21.75)†	57.62 (20.65)†
7–8 years	40.78 (17.51)†	−10.4 (18.39)#†	52.36 (22.40)†	15.24 (24.14)#†	39.12 (26.33)†	47.89 (21.63)†	50.11 (21.27)†
9–10 years	34.42 (20.21)†	−14.06 (13.01)#†	49.55 (23.75)†	14.89 (22.36)#†	42.97 (28.72)†	50.32 (14.23)†	53.95 (19.21)†
11–12 years	20.90 (29.57)†	−15.13 (10.60)#†	40.88 (26.21)†	15.25 (22.49)#†	46.38 (25.88)†	48.74 (21.50)†	46.93 (19.24)†
13–14 years	26.80 (14.18)†	−19.21 (14.12)†	16.28 (29.66)	6.36 (20.33)#	42.05 (27.95)†	49.22 (20.15)†	44.72 (19.74)†
Young adults	-	−27.44 (11.57)†	-	−13.18 (17.81)†	-	36.07 (25.23)†	36.67 (19.50)†

RA Rectus abdominis, ES Erector spinae, RF Rectus femoris, BF Biceps femoris, TA Tibialis anterior, GcM Gastrocnemius medialis, SOL Soleus
The starting time for RA, RF, and TA in adults was not included in this analysis because the activation rate was very low (< 10%). Daggers indicate significant differences relative to the burst onset of the deltoid anterior. †p < 0.05. Sharps indicate significant differences relative to adults. #p < 0.05

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