Engineered Around the Science of Recovery.

Cold water immersion reduced blood flow in the leg: conductance in the main thigh artery fell by about 30 to 40 percent in both 8 °C and 22 °C water (nine men).

Four cryotherapy units each reduced blood perfusion in the skin under the pad. The authors describe a deep state of local vasoconstriction that can persist after cooling ends.

In 23 men, icing the ankle until the skin reached 10 °C slowed nerve conduction by about a third and raised pain threshold and pain tolerance.

A meta-analysis of 36 articles: cooling after exhausting exercise was linked to lower reported muscle soreness at 24, 48 and 96 hours than passive recovery. The trials had a high risk of bias.

A review of how skin blood flow is controlled: local warming of the skin can cause maximal vasodilation in healthy people, while local cooling can reduce skin blood flow to minimal levels.

In volunteers, local heating raised skin blood flow through two separate mechanisms: a nerve axon reflex and nitric oxide.

A review of randomized trials: heat therapy, especially hot-water immersion, appeared the most effective for restoring muscle function after hard exercise. Local heating is less well studied, and contrast therapy looked promising but evidence is limited.

A review of how cold and heat work. Cold reduces blood flow, pain and muscle spasm; heat raises blood flow and the elasticity of connective tissue. The authors note that clinical evidence for both is limited.

A meta-analysis of 32 randomized trials (1,098 people): cold applied within an hour after exercise lowered soreness pain over the next 24 hours, and heat lowered soreness pain as well.

A review of the proposed ways massage may work: mechanical pressure, greater blood flow, effects on the nervous system and a relaxation response.

Vibrating the forearm at 30 or 50 Hz for 10 minutes raised skin blood flow within the first four minutes, peaking by minute five (two small studies, 18 and 7 people).

Five minutes of handheld percussive massage on the calf increased ankle range of motion by about 18 percent in 16 men, with no change in muscle strength.

Two minutes of percussive massage, with or without added heat, increased ankle range of motion and reduced muscle stiffness in 15 men. Strength did not change.

After hard arm exercise, one minute of percussive massage per visit was followed by greater range of motion over the next three days and lower soreness ratings (17 people).

A meta-analysis of 12 studies: compression garments had a moderate effect on reducing soreness after damaging exercise.

In 33 active men, 30 minutes of intermittent compression after hard squats did not change jump or strength recovery compared with a placebo, though perceived soreness trended lower with compression.

A critical appraisal of three trials in endurance athletes: intermittent compression may give short-term relief from muscle soreness, but did not keep helping recovery from muscle damage over time.

A systematic review of 18 trials: contrast water therapy left people less sore than passive rest, with little difference between it and other popular recovery methods. All trials had a high risk of bias.

In 24 healthy men, contrast water therapy made lower-leg blood flow fluctuate throughout a 20-minute treatment. Warm water (40 °C) changed blood flow significantly compared with a control, while cold water (13 °C) did not reduce it significantly.

A meta-analysis of 99 studies: massage, compression garments, immersion, contrast therapy, cryotherapy and active recovery each reduced soreness. Massage had the largest effect on soreness and fatigue.