Table 6.

The incidence of match injuries with different natures and causes on dirt field (DF) and artificial turf field (ATF).

	DF	ATF
Mechanisms of injuries	Injuries Incidence n/1000 h of match exposure (95% CI)	Injuries Incidence n/1000 h of match exposure (95% CI)	Rate ratio (95% CI)	P value (Tow sided)
Nature of onset
• Acute	32.68[25.05-41.89]	16.69[10.58-25.04]	1.95[1.19-3.31]	0.004
• Gradual	4.21[1.82-8.30]	2.90[0.79-7.43]	1.45[0.38-6.59]	0.56
Cause of onset
• Not any contact	15.8 (10.6-22.5)	7.2 (3.4-13.3)	2.17 1.03-4.99)	0.02
• Contact with another player	18.9 (13.2-26.2)	11.6 (6.6-18.8)	1.63 (0.88-3.15)	0.09
• Contact with the ball	0.5 (0.01-2.9)	0 (0-2.6)*	-----
• Contact with other objects	1.5 (0.3-4.6)	0.7 (0.01-4)	2.17(0.17-144)	0.55

(*)one-sided