Table 2.

Between groups comparison of the dependent variables including FHP, US imaging measures and endurance test results.

			Mean ± SD		Mean difference	95% CI of the mean difference	p-value	Effect size
			CNP group	Asymptomatic group
Flexor muscles	LCO	AP	0.46 ± 0.08	0.53 ± 0.09	0.06 ± 0.02	0.02, 0.11	<0.01*	0.82
		CSA	0.42 ± 0.10	0.52 ± 0.13	0.10 ± 0.02	0.04, 0.16	<0.01*	0.86
	LCA	AP	0.35 ± 0.08	0.39 ± 0.09	0.03 ± 0.02	−0.00, 0.08	0.08	0.46
		CSA	0.33 ± 0.13	0.36 ± 0.09	0.02 ± 0.02	−0.03, 0.08	0.36	0.26
	SCM	AP	0.79 ± 0.13	0.86 ± 0.15	0.06 ± 0.03	−0.00, 0.13	0.07	0.49
Extensor muscles	MF	AP	0.29 ± 0.08	0.36 ± 0.12	0.07 ± 0.02	0.01, 0.12	<0.01*	0.68
		CSA	0.21 ± 0.12	0.30 ± 0.20			<0.01*	0.54
	SSCer	AP	0.36 ± 0.07	0.43 ± 0.10	0.06 ± 0.02	0.02, 0.11	<0.01*	0.81
		CSA	0.42 ± 0.11	0.53 ± 0.20			<0.01*	0.68
	SSCap	AP	0.44 ± 0.07	0.47 ± 0.09	0.02 ± 0.02	−0.01, 0.06	0.25	0.37
		CSA	0.72 ± 0.16	0.79 ± 0.21	0.06 ± 0.04	−0.02, 0.16	0.14	0.37
	Sp Cap	AP	0.42 ± 0.08	0.46 ± 0.13	0.04 ± 0.02	−0.01, 0.09	0.16	0.37
Total extensor endurance	166.21 ± 192.32	293.74 ± 184.93			<0.01*	0.67
Local extensor endurance	204.166 ± 197.02	210.76 ± 93.23			0.32	0.04
Global extensor endurance	92.72 ± 115.99	222.73 ± 130.05			<0.01*	1.05
Flexor endurance	29.00 ± 17.88	43.68 ± 26.15	14.68 ± 5.52	3.65, 25.72	0.01*	0.65
FHP	51.31 ± 6.29	49.80 ± 7.31			0.30	0.22

CNP, chronic neck pain; LCO, longus colli; LCA, longus capitis; SCM, sternocleidomastoid; MF, multifidus; SSCer, semispinalis cervicis; SSCap, semispinalis capitis; Sp Cap, splenius capitis; AP, antero-posterior; CSA, cross-section area; FHP, forward head posture; CI, confidence interval.

The FHP, endurance test results, muscles thickness (AP) and CSA expressed in terms of degree, second, cm and cm², respectively. 95% CI has not been reported for non-normally distributed variables.

^*Statistically significant difference.