Table 2. Crude and adjusted URTI incidence rate ratio (IRR) estimates by level of physical activity and studied covariates, fitted in a hurdle regression model.

	Crude						Adjusted
	Positive Counts			Zero-hurdle			Positive Counts			Zero-hurdle
	IRR	95% CI	p-value	IRR	95% CI	p-value	IRR	95% CI	p-value	IRR	95% CI	p-value
Physical activity (MET-h/d)			0.17			0.87			0.46			1.00
< 37.7	Ref			Ref			Ref			Ref
37.7–43.9	1.12	0.89–1.42		1.03	0.87–1.23		1.05	0.83–1.31		1.00	0.84–1.20
≥ 43.9	0.90	0.70–1.14		0.99	0.83–1.18		0.91	0.71–1.15		1.01	0.84–1.21