Table 1. Characteristics of included randomized controlled trials.

Author, year, location	Participants	Interventions			Outcome measures	Main results	Adverse events	Limitations
		Experimental group		Control group
	PopulationSample size, N (EG/CG) Gender, n (male/female) Mean age, years (EG/CG) Drop out, n (%)	Interventions Delivery method Duration Interventionist
Dunleavy et al., 2015, USA/Detroit	Patients with CNP56 (19/20/17) 56 (7/49) 55.6 (-/-/-) 32 (57.1)	Yoga 60 min/day 3 months Physiotherapist	Pilates 60 min/day 3 months Physiotherapist	None	Pain intensity (NRS) Functional disability (NDI)	(p<0.05) (p<0.05)	None	Absence of placebo groups. No blinding. All subjective outcome measures. No long-term follow-up data.
Cramer et al., 2013, Germany/Essen	Patients with CNP51 (25/26) 51 (9/42) 47.8 (46.2/49.5) 3 (5.9)	Iyengar yoga 90 min/week once a week 9 weeks Yoga instructor and physiologist		Exercise 10 min/ay 9 weeks Self-care manual	Pain intensity (VAS) Functional disability (NDI)	(p<0.05) (p<0.05)	Minor adverse effect; a transient worsening of neck pain or muscle soreness, limb pain, migraine, and vertigo after practice	No guide for the control group. Lack of long-term follow-up. No blinding
Michalsen et al., 2012, Germany/Essen	Patients with CNP77 (38/39) 77 (10/67) 47.9 (48.3/47.5) 24 (31.1 )	Iyengar yoga 90 min/week once a week 9 weeks Yoga instructor		Exercise 10 to 15 min/ 3 times a week 9 weeks Self-care manual	Pain intensity (VAS) Functional disability (NDI)	(p<0.001) (p<0.001)	Minor adverse effect; a transient low back pain and muscle soreness after practice	Small sample size. A higher study dropout rate. The research assistant who collected the data were not blinded to the treatment allocations.

CNP: chronic neck pain; EG: experimental group; CG: control group; N: number; NDI: neck disability index; VAS: visual analog scale; SF: short-form; NRS: numeric rating scale