Table 2.

Heritability of CRF and PA

	CRF-vo2max	CRF slope	PA
Combined	0.10 (0.01)	0.08 (0.01)	0.14 (0.01)
Male	0.10 (0.01)	0.09 (0.02)	0.13 (0.01)
Female	0.11 (0.02)	0.10 (0.02)	0.15 (0.01)

Note: Values shown are SNP heritabilities and standard errors on the observed scale. CRF-vo2max maximum volume of oxygen uptake per kg of bodyweight per minute, estimated from workload and heart rate during the cardiorespiratory fitness test, as well as age and weight; CRF slope the rate of increase of heart rate during the exercise period of the cycle ramp test; PA 7-day average physical activity