The Science Of Cooling Down

The Science Of Cooling Down

In a former life (well years ago, before University!) I qualified as a personal trainer and worked in a gym. Flicking through the members’ workout logs revealed one major trend; the true extent to which cooling down is neglected. I would conservatively estimate that 9-out-of-10 regular gym users never did any form of cool-down (in spite of us trainers and our protestations).

I began to wonder recently how footballers might relate to this number?

My observations since then suggest that, at the very least, nine out of every ten coaching sessions or games ends without even the most rudimentary cool-down. I’d be interested to hear your thoughts on the prevalence of cool-downs in your own club or league.

And I’m not sitting on my high horse for this one – I readily admit skipping far more cool-downs than I have ever done. But I also believe that the quickest way to improve relative to the teams around you is to do something they don’t. Might the cool-down therefore provide a massive opportunity to give our players a competitive advantage?

It is easier to find motivation to do anything when you understand the reasons behind the actions. Knowing this, and how begrudgingly coaches include a cool-down, I decided to examine the real-world benefits, and how they come about.

The Competitive Benefits Of Cooling Down

So to discuss the advantages that a cool-down can give our players we need to look at what it actually does to our players’ bodies. The benefits of the cool down can be seen in three distinct physiological areas; the biochemistry of players’ cardiovascular and their respiratory systems and within players’ muscle fibers.

1) Gradually Lowers Heart Rate

Our heart rate rises during prolonged exercise sessions because the increased energy demands of our muscles require greater oxygen supply. This oxygen is carried around the body by red blood cells and thus the faster the heart beats the quicker the oxygen reaches the muscles.

Oxygen is used in the Krebs cycle, by which molecules of pyruvic acid are converted to water and carbon dioxide – this reaction releases ATP (Adenosine triphosphate) molecules which are the direct fuel for muscle contractions. This whole process is known as aerobic respiration and it is preferential to anaerobic respiration, the body’s energy production system in the absence of oxygen, because the ATP yield is 4-5 times higher.

Strengthening the cardiovascular system is therefore a crucial element to building better players. The stronger a player’s heart is, the more oxygen they can provide to the Krebs cycle and the more muscle contractions they can make.

At the end of a training session, or after a game, this process continues but because, in the absence of a cool-down, the heart rate is allowed to drop quickly the oxygen supply is removed suddenly. This means aerobic energy production almost completely ceases.

By cooling down, our players continue their aerobic exercise for longer and condition their bodies to maintain the Krebs cycle inputs at gradually lower heart rates. As the duration that any activity that can be maintained is directly related to heart-rate intensity, players who can provide their muscles with the same amount of energy as their opponents, but at a lower heart-rate, will simply be able to maintain that level of performance for longer.

2) Disperses Lactic Acid

The pyruvic acid molecules used in aerobic respiration are themselves by-products of another process called glycolysis.

The body continuously breaks down complex carbohydrates to glucose. In glycolysis each glucose molecule, via a series of other sugar-phosphates, is used to form two molecules of Glyceraldehyde-3-Phosphate. In anaerobic respiration this is broken down to release a measly 4 ATP molecules (of which only 2 are ‘spare’ and can be used by the muscles).

NADH (I won’t worry you with the long version of this one!) and Pyruvic acid is also released. As long as there is sufficient oxygen supplied by the bloodstream, these are passed into the Krebs cycle and used to fuel aerobic respiration – eventually releasing up to 38 ATP molecules.

However a game of football isn’t as simple as a morning jog!

After extended exercise and particularly in high intensity periods (such as sprinting to join a counter-attack) an oxygen debt will develop – more oxygen is needed for energy production than is being supplied. The result is that lactic acid is produced.

The body will not be able to process this acid as quickly as it is being produced and lactic acidosis will occur. This means the pH level of the blood stream will fall and this partially inhibits the body’s chemical pathways – slowing down energy production and reducing performance.

Another negative side-effect is that acidic muscles have an irritant effect on nerve-endings giving the sharp pain associated with hard exercise (and suspected of being a factor in ‘Delayed Onset Muscle Soreness’; the stiffness and dull aching felt 1-2 days after exercise).

If lactic acid is not dispersed then players will feel cramp. In extreme cases the lactate build-up can cause fuel toxicity.

An effective cool down will redress the balance.

Reducing the intensity to a slow jog or brisk walk will allow oxidation to continue and for the body to break down the excess lactate.

Continuing exercise at a lower intensity will also mean the body can use the NADH molecules to drive further ATP synthesis.

The paradox is that by exercising for a little longer our players can feel much less tired.

Imagine how this might affect player motivation, energy levels and performance at your next training session or on your upcoming match day.

3) Muscle Fiber Realignment

Exercise places a stress on our muscles.

After prolonged or intense exercise the fibres which make up muscular tissue can become disaligned – increasing injury-risk – and shortened. Repeated contraction moves myosin filaments within the muscle closer and closer together. Without further action these filaments will settle into their new overlapping positions and substantially impair flexibility.

Ending a cool-down with careful static stretching will return the myofibrils to their original positions.

Holding the muscles in an extended state for just 10-15 seconds will also dramatically aid recovery. It can mean our players can safely train at full intensity within 2 days of a game instead of 3-4 days, which is the normal recovery period for muscles damaged in intense exercise.

Developmental stretching – taking the joint through the full range of movement for 30-60 seconds – can be used to increase long-term suppleness. Adding a few minutes of stretching to the end of your sessions can decrease the number of injuries your team suffer. When the tight schedule comes around next March, having one extra fit player might make all the difference in your season.

Take Away Points

  • Cooling down improves our players’ stamina.
  • Players leave feeling fresher when they’ve had a cool-down.
  • Cooling down can reduce the time needed between sessions.
  • The likelihood of injuries can be reduced by cooling down.

I’d like to hear if you’ve found this article useful in understanding the mechanics of a cool-down, and whether this kind of information informs your coaching?

Add a comment below, or use the contact form to send me an email.

  • Thanks for your comments Dave, let me know how the kids respond and if they become a bit more enthusiastic about the cool down!
  • dave
    Hi there!
    I'm really impressed that you are addressing the need of cooling down after sport. Im a PE teacher and find it very difficult getting my kids to cool down at the end of the lesson. Now with this breakdown of the main reasons to cool down i can actually give them the details of why its so important.

    Thanks, Dave.
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