How does the timing of the cool-off phase affect the recovery?

Question

When I see descriptions of training sessions there is almost always a warm-up phase, followed by e.g. a HIT unit, and finally a cool-off phase.

From my understanding, the warm-up phase would be used to warm up the muscles and prevent injuries. I assume the cool-off phase is for recovery.

Question: What would be the effect if one would do the cool-off phase 10, 30, 60, 600 min after the HIT unit (instead of doing it directly after it)?

Background: If I do an indoor cycling session at the gym I would anyway drive home or to work with a bike afterwards or in the evening (after work). So between the HIT unit and the cool-off phase I would prefer to shower and change clothes (~30 min) or go to work (8 hours). So I am thinking about skipping the cool-off phase right after the HIT unit and do it while I drive home.

Answer 1

The timing of the cool-down phase of exercise does not affect recovery, because there is no benefit to performing a cool-down after exercise.

Based on Do We Need a Cool-Down After Exercise? A Narrative Review of the Psychophysiological Effects and the Effects on Performance, Injuries and the Long-Term Adaptive Response, this systematic review found that the only positive effects that existing research had demonstrated for the use of cool-downs were reductions in blood lactate and immune cells, but then there was no evidence that either of those things were actually beneficial. There was no benefit for muscle soreness or risk of injury. It concludes as follows:

This review shows that an active cool-down does generally lead to a faster removal of lactate in blood, but the practical relevance of this findings is questionable, especially because lactate is not necessarily removed faster from muscle tissue and because lactate may not be the cause of metabolic acidosis. Furthermore, an active cool-down can partially prevent the depression of circulating immune cells counts after exercise. However, it is unknown whether this also leads to fewer infections and illnesses. An active cool-down can also result in a faster recovery of the cardiovascular and respiratory system after exercise, but it remains unknown whether this leads to a reduction in the number of post-exercise syncopes and cardiovascular complications. In contrast, an active cool-down generally does not significantly reduce delayed-onset muscle soreness or improve the recovery of indirect markers of muscle damage. It also does not significantly alter the recovery of the neuromuscular and contractile properties, improve range of motion, or attenuate musculotendinous stiffness following exercise, and may even interfere with glycogen resynthesis. Furthermore, an active cool-down does generally not significantly facilitate the recovery of hormonal concentrations, and it also does not affect measures of psychophysiological recovery.

If your schedule makes performing a cool-down inconvenient, then you can simply skip the cool-down without concern.