Summary

Isometric weight training is a well-recognised technique used by fitness trainers to increase muscle strength. We report a case of a flexor digitorum superficialis muscle belly rupture that occurred during this form of muscle training. Rupture of the belly of the forearm flexor muscles is rare. When the muscle undergoes tractional force in isometric weight training, there is a potential for it to rupture and result in the formation of a haematoma. This can lead to raised intracompartmental pressures which would require treatment with urgent fasciotomy. An awareness of this potential injury mechanism will help with early recognition and appropriate treatment.