imply weightlifting -> exercise

BUR #11900 has been approved by @nonamethanks.

create alias lifting_weights -> weightlifting
create implication weightlifting -> exercise

It's a subset.

BUR #11901 has been approved by @nonamethanks.

create implication sit-up -> exercise

This one too

The bulk update request #11900 (forum #219819) has been approved by @nonamethanks.

The bulk update request #11901 (forum #219820) has been approved by @nonamethanks.