Table 1

Significant muscle strain match injury risks after binary logistic regression analysis

Muscle strain type	Risk factor*	Unadjusted OR (single variable)	Adjusted OR (multivariable)*	95% CIs (for adj OR)		P value
Hamstring	Recent hamstring	7.96	13.10	11.52	14.89	<0.001
	Non-recent history hamstring	2.34	3.49	3.15	3.86	<0.001
	Recent calf	1.63	1.49	1.04	2.11	0.03
	Indigenous player	1.65	1.34	1.16	1.55	<0.001
	Past ACL	1.55	1.23	1.03	1.46	0.02
	Past concussion	0.91	0.77	0.63	0.94	0.01
	Substitute rule (2011–2014)	0.78	0.76	0.67	0.86	<0.001
Calf	Recent calf	10.66	13.30	9.62	18.38	<0.001
	Non-recent history of calf	4.54	4.38	3.56	5.39	<0.001
	Recent hamstring	1.89	1.75	1.17	2.60	0.01
	Age 24 or more	2.27	1.62	1.32	1.98	<0.001
	Substitute rule	1.89	1.59	1.30	1.94	<0.001
	Past knee cartilage	0.94	0.68	0.48	0.96	0.03
Quadriceps	Recent quad	17.70	25.19	18.75	33.84	<0.001
	Past not recent quadriceps	3.86	5.16	4.17	6.38	<0.001
	Recent hamstring	2.00	1.80	1.20	2.71	0.01
	Local league match	1.36	1.50	1.23	1.83	<0.001
	Substitute rule	0.68	0.70	0.53	0.92	0.01
Groin	Recent groin	14.72	20.62	17.02	24.99	<0.001
	Past not recent groin	2.37	3.46	2.97	4.03	<0.001
	Local league match	1.35	1.36	1.19	1.57	<0.001
	Past ankle	0.90	0.82	0.69	0.98	0.03
	Substitute rule	0.80	0.78	0.65	0.93	0.01

*All risk factors being binary are compared with the opposite condition as the reference group (ie, recent hamstring strain OR is the odds of injury for players who have suffered a recent hamstring strain compared with all players who have not suffered a recent hamstring strain).
ACL, anterior cruciate ligament.