His wife, Susie Wolff, revealed that the injury was caused while mountain biking.
“Action-packed start to the summer holidays,” Susie posted to social media. “Last picture shows how the downhill mountain biking ended for Toto…”
F1 is currently amid its summer break – an FIA rule enforces that every F1 team must shut its factory for 14 days.
Mercedes team principal Wolff took the opportunity to go on a family holiday where he was injured.
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Other images shared by Susie showed their son skateboarding and karting.
It is not the first time that Wolff’s arm has ended up in a sling after a day of cycling. In 2014, it was again his wife who revealed via social media that he had fallen and injured an arm.
Wolff will be back in action when F1 resumes on August 25-27 in the Netherlands.