Muscles are made up of individual cells called muscle fibres. With a light weight, type 2 fibres only become activated as the type 1 fibres fatigue later in the set. Research comparing failure and non-failure training has also found that recovery can take longer after sets performed to failure. Failure training during these exercises is best avoided unless suitable safety equipment or a competent spotter is available. A 2022 systematic review and meta-analysis found no significant overall difference between failure and non-failure training for strength or muscle growth.