Arnold's daughter Katherine is expecting her first child with husband Chris Pratt

 ARNOLD Schwarzenegger covered up with a face mask during a bike ride with his son David Baena on Friday in Santa Monica, California.

Arnold rocked a black “Arnold Classic” t-shirt with a model shot from his body-building days printed on the front

Their father-son outing comes as news broke that Arnold’s daughter Katherine Schwarzenegger, 30, is expecting her first baby with actor Chris Pratt.

The 40-year-old actor and his wife are reportedly pregnant ten months after they wed last June, according to People.

Katherine debuted her baby bump while on a bike ride on Saturday

This will be the first child for the couple - who wed 10 months ago