Cooling down is the act of allowing the body to return to homeostasis or its natural equilibrium. There are two ways of going about this, passively and actively. Passive cool down is defined as involving minimal or no voluntary exercise/movement. Examples include sitting, lying down, massage, cold water immersion, lying motionless like a corpse in a floatation tank or hyperbaric chamber and so on. Active cool down is defined as any voluntary low to moderate intensity exercise done within one hour of training. Examples include jogging, cycling, low intensity resistance training, swimming and what not.
It never made sense to me that jogging after tennis would cool me down while jogging before tennis would do the exact opposite. Coaches might justify exercising after exercising as a means to prevent cardiovascular complications, but such correlation remains ambiguous. The primary purpose of a cool down should be to facilitate physiological recovery. Recovery is the time it takes for our performance (strength) to return to pre-workout levels. It isn’t uncommon for athletes to train twice a day, and is quite often the norm. Sustaining high performance becomes a function of ones ability to recover. While it sounds intuitively correct that if you warm-up, you must cool down, such reasoning is weak and unconvincing. In my opinion, five broad indices exist when evaluating a cool down:
How effective are they at clearing out metabolic wastes that could be toxic?
Do they leave you feeling less sore in the days after?
Can any range of motion lost during play be restored?
How does the athlete feel mentally as a result?
How effective are they at rebooting the nervous and muscular systems?
Do cool downs achieve the above or is that a tall order? Let’s find out…
Below: passive cool down interventions.
1.Clearing metabolic by-products:
Muscles need oxygen to produce energy. As the intensity of an activity increases, oxygen supply cannot keep up with its demand. When this happens, the body depends on lactate to produce ATP. A problem arises when this helpful molecule lactate is produced faster than it can be cleared (to produce ATP). The point at which this occurs is called lactate threshold. The concentration of lactate in the blood is used as a marker of fatigue and by extension, recovery. This might cause you to believe that the faster lactate is cleared, the better. There are several studies that show that active cool downs do a better job of clearing lactate faster than passive cool downs. However when you consider how efficient the body is at its job, this benefit gets diluted. Lactate levels can return to baseline within an hour without doing anything. We’ve known this since the early 20th century. Researchers from the Harvard fatigue lab put forth that one half of lactic acid at the end of exercise is cleared in 15 minutes.
While there is sufficient evidence in favour of active recovery’s ability to remove lactate faster, the utility of doing so is open to contestation. In most sport scenarios the time gap between two successive matches or training sessions is more than 2 hours, and it would be safe to assume that lactate clearance would have occurred irrespective of recovery modality. In the rare occasion that the rest period is less than ideal, an active recovery might be worth playing around with.
2.Delayed Onset Muscle Soreness (DOMS):
Delayed Onset Muscle Soreness is the pain or discomfort experienced in the days following exercise. Lactic acid was believed to the be the cause of this, and has since been successfully debunked. Makes sense when you consider the following. We know that lactate is cleared in the minutes or hours after exercise, whereas DOMS usually peaks 24-72 hours after exercise. Further we know that due to the repeated bouts effect, we get less sore from each repetitive workout. On the contrary, lactate doesn’t differ much between accustomed and unaccustomed exercises as seen in trained and untrained individuals. What causes DOMS is still a mystery.
Does an active cool down reduce DOMS? Yes and No. It does not improve subsequent performance, hormonal profile or muscle pain. Your ability to produce force on the same day or the next is still going to be impaired. However, it does improve subjective measures of recovery. It can favourably alter perceptions of fatigue which can improve ones readiness to exercise.
Soreness is something we all have to learn to deal with. The next time you’re extremely sore, it might be worthwhile to spend more time warming up. There is some weak evidence to suggest that warm-ups can reduce DOMS, albeit minutely.
3.Range of Motion (ROM):
The overhead throwing motion is a highly dynamic one that often exceeds the physiological limits of the joint. Repetitive action could overload the joint and predispose it to injury. It is well documented that overhead athletes lose internal rotation (IR) of the shoulder and this occurs linearly with age and hours of play. This deficit in IR between the dominant and non-dominant arm is associated with the development of shoulder injuries. This holds good for female athletes as well who show intrinsically greater flexibility. While these deficits are probably adaptations to the sport, it would serve us well to minimise them especially before the next session/match.
There appears to be mild evidence that a combination of active and passive recovery modalities confer greater benefit than doing either/or. Specifically in a study on baseball pitchers, a combination of light shoulder exercises (active) and cryotherapy (passive) showed greater improvements in strength, ROM and soreness than just cryotherapy. Cryotherapy decreases stretch sensitivity and increases pain threshold which could explain the improvements in ROM. There’s a lot more to icing that calls for a separate post in itself. As always, the results of a study can never be taken at face value and are to be interpreted with caution. The study had no control group (the no treatment group) to which results could be compared. It would be interesting to see if sitting on your ass could be just as effective. Further, lack of a non-cryotherapy group is needed to compare the effects of icing. Additionally, no guidelines as to the intensity or volume of shoulder exercises has been determined. It’s easy to overdo “light” shoulder exercises that leave you worse for wear.
The only practical takeaway from this is that if you like taking ice baths to recover and feel that you benefit, keep at it. If you haven’t tried it, give it a try before you decide to throw the ice out with the bathwater. There could very well be a placebo effect and the modified perception of fatigue might improve work output.
4.Psychological variables:
Simulated and actual match-play result in elevated ratings of perceived exertion (RPE), muscle and joint soreness and suppressed mood states. These negative states of perceived wellness and soreness are then exacerbated by consecutive on-court efforts. (Reid, 2014)
The degree to which increased RPE translates to impaired movement quality and stroke mechanics is notional, but it would be safe to assume a correlation exists. Further, one of the early signs of overtraining is a lack of motivation or willingness to train. Therefore, it would be remiss to ignore psychological recovery as it is intertwined with physiological recovery. One of the more worthwhile benefits of an active cool down is the fact that it is perceived to be more helpful. This is more likely the case with water-based cool downs. Even though active cool downs don’t significantly improve sleep and mood states, the mere expectation of benefit from a novel/different stimulus can positively affect the individual. Active cool downs can exhibit the belief effect, that is best encapsulated as “if it works, it works.”
Even though active cool downs are perceived to be better, the true markers of recovery are objective sports performance. No matter how recovered you perceive yourself to be, if you’re sprinting slower or not jumping as high, you haven’t fully recovered.
5.Neuromuscular function and Muscle damage:
Fatigue can be defined as a temporary and reversible reduction in our capacity to voluntarily produce force. There are broadly two kinds, peripheral (fatigue of the muscle) and central (fatigue of the central nervous system). Of importance to us is muscle damage (longer term peripheral fatigue) and central fatigue as these take longer to recover from. Given the need to quickly change direction, decelerate frequently and overload repetitive patterns (especially deceleration on the serve), tennis players are exposed to high levels of muscle damage.
Several studies report the blunted ability to maximally produce force or maximise muscle recruitment following prolonged match-play.A collection of evidence notes the reductions in running speed, maximal voluntary strength and leg stiffness during match-play. These examples explicitly highlight that there is a reduction in neuromuscular function, particularly of the lower body, during match-play greater than 2 h. Further, maximal voluntary contraction is reported to be reduced over consecutive days of match-play. (Reid, 2014)
The question is whether active cool downs mitigate compromised neuromuscular function. Most of the research suggest that active cool-downs confer no significant advantage over passive ones. Recovery modalities like running can even exacerbate muscle damage given its repetitive deceleration component. Cycling or water based exercises would be a safer bet. While it may sound trite, getting adequate sleep, hydrating well, having a balanced nutrition regimen, good fitness levels and low psychological stress can do quite a bit to improve recovery.
Fatigue is multi-factorial in nature. It is a combination of dehydration, glycogen depletion, muscle damage, mental fatigue and much more. Even though our capacity to catalyse recovery might be limited, our ability to get better competing under fatigue is a lot more adaptable. The only way to get better at handling fatigue is to play longer, fatiguing matches more often. Expose yourself to the demands of the game more frequently. It isn’t too farfetched to say that better players play better even when fatigued. Playing a 5 hour tennis match calls for as much genetic freakery as for hard earned adaptation.
Takeaway:
Most of the research paints a very ambivalent picture of active recovery. We know that cool downs play an important role even if they don’t improve actual physiological recovery. There’s a reason elite athletes have diligent cool down routines and that might be as simple as them feeling better. The problem with current research is its short-term nature and use of non-elite athletes. It would be interesting to see a longitudinal study on a more sensitive population (elite athletes) where even a small effect would be significant. To them, cooling down is a process, and trusting the process might bestow a slight but significant competitive edge. It takes a while before anecdotal experience can be underpinned by scientific rationale. Until then, instilling a process borne out of experimentation will do you good to follow. At the end of the day, if it works, it works. It might sound hackneyed but a good place to start would be to prioritise sleep, hydration and minimising stress.
Remember cooling down is about maintaining, and not improving performance. You can only maintain what is present. If you only have the ability to play two sets before dropping like a beached whale, no amount of cooling down is going to help. Test yourself against the demands of the game to know what exactly you have to recover from. Adaptation (getting better at handling fatigue) only takes place when the stimulus (training) can be recovered from. Equally, if not more important is dosing the stimulus appropriately. Too many coaches do an abysmal job of monitoring workload. Overreaching on a regular basis could be a recipe for disaster. If you experience a frequent lack of desire to train, an analysis of your workload is a good place to start.
In essence, pay attention to two things. First, given your current level, what are you realistically expected to recover from. Second, what recovery protocol works for you. This is largely a process of trial and error. If it makes you feel less crappy, that’s more than you can ask for.