In 2020, Dubois and Esculier proposed a paradigm shift in the acute management of musculoskeletal injuries, advocating for the transition from the traditional PRICE protocol- Protect, Rest, Ice, Compression, Elevation-to the more holistic PEACE & LOVE framework. This updated model emphasizes Protection, Elevation, Avoiding anti-inflammatories, Compression, and Education, followed by Load, Optimism, Vascularization, and Exercise. Notably, the PEACE & LOVE approach omits the use of ice, a decision that has sparked considerable debate. While the rationale centers on avoiding interference with the natural inflammatory and regenerative processes, this omission stands in contrast to a substantial body of animal research suggesting that cryotherapy can mitigate secondary tissue injury by reducing inflammation and metabolic activity. Despite its widespread clinical use, human studies have yet to provide conclusive evidence supporting or refuting the efficacy of cryotherapy in acute injury management, leaving clinicians to navigate between tradition, emerging evidence, and evolving philosophies of care. Even though it is important to consider natural inflammation for a better regenerative process, animal models have shown that the original injury can elicit oxidative stress, which will enhance cellular damage (secondary damage) and inflammation. Clinically, it is unknown if this secondary damage would increase functional impairment.

Therefore, this proposal will determine if cryotherapy can decrease secondary damage, after exercise-induced muscle damage, and if this decrease is associated to lower inflammation, oxidative stress and functional impairments.

This study is a randomized, double-blind, controlled clinical trial with 3 independent groups. One group (control-control or CON-CON) will not exercise and will not have any cryotherapy intervention, a second group (control or CON) will exercise but use a "room temperature" cold-pack, and the cryotherapy group (CRYO) will exercise and receive a cold cold-pack every day for 15-min.

We anticipate to compare means in several markers (functional and in blood) using a two-way analysis of variance (ANOVA, time x condition) where time is before, and 0, 24, 48, 72, 96, and 264 hours after exercise (6 visits) and conditions are CON-CON, CON, and CRYO.

VISIT ONE Before the informed consent process, potential participants will rest for 10 minutes, and their blood pressure will be taken to confirm eligibility. Once eligibility is confirmed, participants will go through the informed consent process. After the participants have signed the informed consent, the participants will be randomly allocated to one of the 3 groups. Then, a blood sample (two 10-ml tubes) from an antecubital vein of the dominant arm will be drawn. After the blood drawn, a set of functional tests ( i.e., arm girth, active range of motion (ROM), peak pressure threshold (PPT), and maximal voluntary isometric contraction (MVIC)) will be performed (the description of each test can be found below). Once the functional tests are performed, participants from the CON-CON group will be dismissed. Participants from the other 2 groups will perform a controlled exercise-induced muscle damage (EIMD) through eccentric exercise (protocol description below). Immediately after the EIMD protocol, participants in the CON group will receive 15-min of a room temperature cold-pack in room RSC 100. Participants in the CRYO group will receive 15-min of a cold cold-pack in room RSC 100. Treatment will be performed by RAs that were not involved in any testing session. After treatment, CON or CRYO, the same set of functional tests will be performed in room RSC 117.

VISIT TWO to FOUR (24, 48, and 72 hours after VISIT 1, respectively) Participants will get a blood draw (two 10-ml tubes) from an antecubital vein of the dominant arm. Then, participants in the CON group will receive 15-min of a room temperature cold-pack in room RSC 100. Participants in the CRYO group will receive 15-min of a cold cold-pack in room RSC 100. Treatment will be performed by RAs that were not involved in any testing session. Participants from the CON-CON group will not have any treatment. Finally, the set of functional tests will be performed.

VISIT FIVE (96 hours after VISIT 1) Participants will get only a blood draw (two 10-ml tubes) from an antecubital vein of the dominant arm. Then, participants in the CON group will receive 15-min of a room temperature cold-pack in room RSC 100. Participants in the CRYO group will receive 15-min of a cold cold-pack in room RSC 100. Treatment will be performed by RAs that were not involved in any testing session. Participants from the CON-CON group will not have any treatment.

VISIT SIX (264 hours after VISIT 1) Participants will get a blood draw (two 10-ml tubes) from an antecubital vein of the dominant arm. Then, the set of functional tests will be performed.

Inclusion Criteria:

• apparently healthy
• normotensive
• non-smokers (all tobacco products including e-cigarettes)

Exclusion Criteria:

• Cardiovascular diseases (including hypertension)
• pregnancy
• any musculoskeletal injury 6 months prior the study

I might share un-identified data when submitting manuscripts, if asked to do so.