The effect of single-handed lifting tasks on the activation of the neck-shoulder shared musculature

Figures & data

Figure 1. View of the distribution of loads.

Figure 2. Participants performing lifting activities.

Table 1. Results of the separate ANOVA tests on the NEMG magnitude for the six muscles measured right sternocleidomastoid (SCM), upper trapezius (TRAP), and the levator scapulae (LEV).

Effect	Muscle
	Right
	TRAP			SCM			LEV
	DF	F-Value	P-Value	DF	F-Value	P-Value	DF	F-Value	P-Value
Gender	1	65226.81	*	1	50537.89	*	1	9256.03	*
Weights	4	1519.52	*	4	865.75	*	4	1010.10	*
Heights	1	1427.21	*	1	872.20	*	1	2165.01	*
Reach distance	1	4209.88	*	1	2442.19	*	1	8160.60	*
Angles	4	517.64	*	4	300.18	*	4	1010.10	*
Gender × Reach distance	1	548.97	*	1	339.28	*	1	97.61	*
Gender × Height	1	167.70	*	1	118.25	*	1	31.78	*
Gender × Angle	4	67.83	*	4	41.43	*	4	11.78	*
Gender × Weight	4	188.80	*	4	121.92	*	4	32.99	*
Height × Reach distance	1	9.36	*	1	4.60	*	1	16.60	*
Height × Angle	4	2.40	*	4	8.5	*	4	3.82	*
Height × Weight	4	3.01	*	4	10.67	*	4	5.21	*
Angle × Reach distance	4	5.64	*	4	12.38	*	4	10.24	*
Angel × Weight	16	1.81	*	16	6.93	*	16	3.31	*
Weight × Reach distance	4	11.01	*	4	19.93	*	4	20.36	*

Note:

Stars indicated a p-value less than 0.05.

Table 2. Tukey pairwise comparisons (means that do not share a letter are significantly different).

Muscles
UTAP							SCM						LEV
Loads	N	Mean	Grouping				Loads	N	Mean	Grouping			Loads	N	Mean	Grouping
3.0	200	33.113	A				3.0	200	23.868	A			3.0	200	37.683	A
2.5	200	31.175	A	B			2.5	200	22.498	A			2.5	200	35.245		B
2.0	200	29.303		B	C		2.0	200	21.117	A	B		2.0	200	32.840			C
1.5	200	27.178			C	D	1.5	200	19.667		B	C	1.5	200	30.179				D
1.0	200	52.236				D	1.0	200	18.302			C	1.0	200	27.735					E
Angles	N	Mean	Grouping				Angles	N	Mean	Grouping			Angles	N	Mean	Grouping
90.0	200	31.522	A				90.0	200	22.741	A			90.0	200	35.679	A
67.5	200	30.364	A	B			67.5	200	21.907	A	B		67.5	200	34.214	A	B
45.0	200	29.166	A	B	C		45.0	200	21.085	A	B		45.0	200	32.697		B	C
22.5	200	28.026		B	C		22.5	200	20.275	A	B		22.5	200	31.264			C	D
1.0	200	26.927			C		1.0	200	19.445		B		1.0	200	29.827				D

Table 3. Significant variables for co-contracting muscles.

	NEMG left UTAP	NEMG left SCM	NEMG left LEV
Variable	NEMG right UT	NEMG right SCM	NEMG right LS
R^2	0.74	0.96	0.71

Table 4. Regression models for antagonistic muscles.

	Regression models for the co-contracting muscles	R^2
NEMG left UT	5.245 + 0.689 (NEMG right Upper Trapezius)	0.74
NEMG left SCM	−1.325 + 0.61178 (NEMG of right SCM)	0.96
NEMG left LS	5.116 + 0.2694 (NEMG right Levator Scapula)	0.71