Table 3 Intra‐cohort analysis of injury incidence on artificial turf and grass.

	Artificial turf		Grass
	No	Incidence	No	Incidence	RR (95% CI)
Training injuries (trauma)
Total	124	2.42	54	2.94	0.82 (0.60 to 1.13)
Slight	38	0.74	20	1.09	0.68 (0.40 to 1.17)
Minor	33	0.64	10	0.54	1.18 (0.58 to 2.40)
Moderate	35	0.68	20	1.09	0.63 (0.36 to 1.09)
Severe	18	0.35	4	0.22	1.61 (0.55 to 4.76)
Lower extremity	115	2.24	48	2.62	0.86 (0.61 to 1.20)
Sprain	48	0.94	12	0.65	1.43 (0.76 to 2.70)
Ankle sprain	27	0.53	6	0.33	1.61 (0.67 to 3.90)
Knee sprain	16	0.31	6	0.33	0.95 (0.37 to 2.44)
Strain	32	0.62	24	1.31	0.48 (0.28 to 0.81)**
Hamstring strain	14	0.27	8	0.44	0.63 (0.26 to 1.49)
Groin strain	7	0.14	6	0.33	0.42 (0.14 to 1.24)
Match injuries (trauma)
Total	142	19.60	129	21.48	0.91 (0.72 to 1.16)
Slight	36	4.97	35	5.83	0.85 (0.54 to 1.36)
Minor	44	6.07	40	6.66	0.91 (0.59 to 1.40)
Moderate	46	6.35	41	6.83	0.93 (0.61 to 1.42)
Severe	16	2.21	13	2.16	1.02 (0.49 to 2.12)
Lower extremity	128	17.66	107	17.82	0.99 (0.77 to 1.28)
Sprain	51	7.04	34	5.66	1.24 (0.81 to 1.92)
Ankle sprain	35	4.83	16	2.66	1.81 (1.00 to 3.28)*
Knee sprain	15	2.07	16	2.66	0.78 (0.38 to 1.57)
Strain	27	3.73	37	6.16	0.60 (0.37 to 0.99)*
Hamstring strain	13	1.79	14	2.33	0.77 (0.36 to 1.64)
Groin strain	6	0.82	9	1.50	0.55 (0.20 to 1.55)

*p<0.05, **p<0.01.

RR, Rate ratio.