Effects of Immediate and Delayed Repeated Cold Exposure After Physical Exertion: A Randomized Controlled Trial.

BACKGROUND

Local cryotherapy is widely used to support recovery after exercise-induced muscle damage, but the optimal timing of cold application remains unclear. This study evaluated whether immediate or delayed local cooling influences recovery from exercise-induced muscle fatigue.

METHODS

Forty-eight healthy adults (39 women, 9 men; age 22 ± 3 years) performed a single-leg eccentric leg-extension protocol to induce delayed-onset muscle soreness (DOMS) and were randomized to immediate cooling (ICG), delayed cooling (DCG; starting 24 h post-exercise), or control (CG) in a 1:1:1 ratio. Reusable gel packs (20 min per session) were applied to the vastus lateralis. DOMS, maximal voluntary isometric contraction (MVIC), creatine kinase (CK), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and ultrasound-derived muscle thickness (MT) were assessed at baseline and at 24, 48 and 72 h post-exercise and analyzed using linear mixed-effects models.

RESULTS

No condition or condition-by-time interactions were detected for the primary outcomes (DOMS, MVIC). Significant linear time effects were observed for DOMS, CK and ESR; MVIC decreased acutely and gradually recovered. A contrast-specific time-by-condition interaction for CRP did not indicate a systematic recovery advantage, and MT showed only minor temporal fluctuations.

CONCLUSION

Neither immediate nor delayed cooling provided a meaningful recovery advantage over the control. The protocol reproducibly elicited fatigue and recovery dynamics, supporting its utility as a framework for future cryotherapy research.