Through my work as a sport psych coach, I devote a great deal of focus to… focus. Experience tells me that success and failure in sport is often closely tied to our ability to focus on the right thing at the right time. In particular, our ability to make decisions (cognition) and to execute skills (motor skills) are underpinned by our focus. There are a number of psychological approaches that we can use to hone our focus, such as simplifying and clarifying our job (finding our ‘Two Lengths of the Pool’). However, our mind and our body are interconnected. Therefore, our physiology also plays a part. If you’re like me, you might notice that your thinking and feeling state changes when you get tired or hungry. Personally, my mood can nose-dive when my energy level plummets. It shows me how my psychology is inextricably tied to my physiology.
A few years ago, whilst working with an English Premier League football team, we spent time understanding how fatigue and dehydration affected our players. We needed to know how to spot signs of fatigue early. Interestingly, we noticed that vision, visual acuity, decision making and response time became compromised initially. For example, the players might not spot opportunities or respond quickly enough to take the opportunities. Soon after that, we noticed that fine motor skills and execution also became affected. Players made more errors. These all came before the players levels of athleticism and endurance started to drop.
Of course, this doesn’t just apply to football. For the past couple of seasons, I’ve been working in elite professional cricket. In cricket, batsmen often face 80-90 mph deliveries. As a consequence, they need to have razor sharp focus and constantly make split-second decisions. Their visual acuity, decision making and execution are tested for long periods of time (sometimes sessions lasting 2-3 hours). Therefore, their ability to maintain focus is critical to their success.
So, I asked sports physiologist and hydration expert, Dr Stephen Fritzdorf, how we can help our players to optimise their hydration in order to enhance focus. Interestingly, his insights into hydration go way beyond cricket, and even sport. The same principles can help us enhance our own focus. As you read on, think, “How does this apply to me?”.
Imagine a cricketer playing a one-day game in normal British weather conditions. If his role is physically demanding, such as a fast bowler, wicket-keeper, or batsman, for example, then he will sweat more; perhaps up to 1.5 litres/hour for a particularly sweaty and active player. If he is fielding in a position that doesn’t require as much physical activity, then he might only sweat at a rate of 500ml per hour.
During a three hour session, a less-active fielder might lose about 1.5 litres of fluid in sweat. If he started the innings weighing 80kg, and drinks nothing during the innings, then he will finish weighing 78.5kg – a loss of about 2% of his bodyweight. There is no evidence in the scientific literature, to suggest that this level of dehydration will affect the kind of muscular performance required in cricket fielding. He should be equally capable of sprinting 50metres, fielding and throwing the ball, at the beginning and at the end of the session.
The fast bowler (who is exerting himself) and the keeper (who is active for every ball and is wearing gloves, pads and a helmet) may lose up to 4.5 litres in the session. This is equivalent to a 6% loss of bodyweight. Again, there is no evidence in the scientific literature to say that this level of dehydration will have an effect on jumping ability (for the keeper) or sprint or arm speed (for the bowler). There is evidence that this level could affect endurance performance, such as playing a football match or running a marathon for example, but not the short-duration very high intensity “anaerobic” activities that cricketers perform. The bowler will be able to bowl just as fast, and the keeper dive just as powerfully.
Or at least this applies for activities that are purely physical brute efforts. But bowlers don’t just run and bowl as fast as they can; they have to do that in a co-ordinated way. And keepers don’t just jump. They have to keep their mind focused, and make quick decisions. There is evidence to show that dehydration affects motor skills, as well as cognition.
In a scientific study performed in Australia, Devlin et al., 2001 asked bowlers to bowl at a target under normal conditions, and when they were dehydrated (to about 3% loss of bodyweight). Their bowling velocity was the same in both conditions, but their accuracy (ability to hit the target) was worse when they were dehydrated.
There is also some good evidence that even quite low levels of dehydration can affect cognition. For example, Shirreffs et al (2004) restricted fluid intake in 15 participants, leading to them becoming dehydrated by about 1-3% of bodyweight. They reported that their ability to concentrate and their alertness were reduced when dehydrated. So think of the batsman facing 90 mph deliveries, who may lose 2% of his bodyweight in the first 90 minutes of his (hopefully long) innings.
What can we do about it? How can we optimise performance? How can we prevent dehydration affecting our performance?
1. Start the match correctly hydrated.
On the morning of the game (in fact, throughout the day), check your urine colour when you go to the toilet. Dark urine could be a sign of dehydration, so if you have dark urine – take a drink. You are aiming for pale yellow urine in moderate quantities – not to drink so much that your urine is pure water, and that you are constantly taking toilet breaks.
Then, about 1 hour before you expect to walk onto the pitch, top up your fluid stores by drinking about 500mL of fluid. This could be a combination of tea, coffee, juice, water – whatever takes your fancy (but maybe 500mL of coffee is a bit much!).
Go to the toilet just before you go out to play to take one last check of urine colour – maybe you need a 250mL top-up at this point, if your urine is still dark.
2. Know your sweat rate.
To measure your sweat rate, weigh yourself before and after your activity. If you have lost 1kg in 1 hour, then you know you that your sweat rate is 1L/hour, and your hydration strategy should be to drink about 1L/hour. You might want to try this in different situations, i.e when doing different activities and in hot and cool conditions, so that you can change your strategy depending on the circumstances.
There are online hydration calculators that can help you with this, such as the smartphone app “Quench – Your Hydration Coach”.
3. Use the drinks breaks wisely.
You have got onto the pitch in a good state, and you know the rate at which you lose fluid. This means that during the drinks breaks, you will know how much fluid to take on-board to keep you optimally hydrated. But be prepared to adjust. If you feel thirsty, then it is OK to drink more than you planned.
4. Use the end of sessions wisely.
Weigh yourself at the start and end of each session. If you have lost weight, then that is because you have sweated out more fluid than you have taken in, so drink something to get your weight back up. Be careful that you do this correctly, though. Go to the toilet before weighing, and make sure you wear exactly the same clothing every time you weigh yourself. The Quench app can help you with this, too.
References
Devlin, L.H., Fraser, S.F., Barras, N.S, & Hawley, J.A. (2001). Moderate levels of hydration impairs bowling accuracy but not bowling velocity in skilled cricket players. Journal of Science and Medicine in Sport 4(2): 179-187.
Shirreffs, S.M., Merson, S.J., Fraser, S.M., & Archer, D.T. (2004). The effects of fluid restriction on hydration status and subjective feelings in man. British Journal of Nutrition 91: 951–958.