Dehydration
With the warm weather slowly descending on the UK shores (well warm to us) hydration is always an important issue to active people and athletes, be they professional or amateur. However this blog has a slight twist to it. I am looking at the affects of dehydration on our physical performance in BJJ from the hobbyist to the competitor who cuts weight for small gains (or big). The affects of dehydration can affect either person.
Cutting weight is something that has been going on in combat sports for many years – and something that will continue for years to come. You hear of people cutting in excess of 3 or 4kg in a week (even more). I myself have gone from 83.4kg to 78.8 in just over 7 days. Most, if not all of this weight would have been water and therefore I would have been in some state of dehydration during that competition
.
Research has been conducted in various surroundings with the most compelling being done within the running and cycling environment.
Firstly the importance of hydration is universally known – but the simple facts for me are this. Once we start getting into a state of dehydration our blood volume decreases and causes it to thicken. With thicker blood our heart (cardiovascular system as a whole) has to work harder to move that blood around our body to help our muscles/organs function. The more dehydrated we become the body diverts blood from inactive organs to the working muscles. One inactive organ would be skin and without blood, the skin decreases the sweating response and thus our body temperature increases further – a vicious circle.
Before getting into the cusp of this blog I feel I need to highlight the different states of dehydration that I believe are relative to us as BJJ competitors/practitioners. There is exercise induced dehydration (speaks for itself) and hypohydration. Hypohydration refers to dehydration that was induced prior to the exercise session of interest – in simple terms, cutting weight.
Research into exercise induced dehydration has suggested at just 2% dehydration (2% of your body weight – 80kg man losing 1.6kg due to dehydration or by cutting weight) performance (VO2) is decreased by up to 20% Bardis et al, (2013). While this specific research was conducted in a cycling environment a 20% reduction in your VO2 capability will affect your performance no matter what sport. An alternative paper found time to exhaustion was reached 31% quicker when dehydrated, Walsh et al, (1994) – in a 5 minute roll that could equate to just over 1 and ½ minutes.
Limited study has been done on affects of dehydration (both exercise induced and hyphydration) on muscle fuel metabolism. Febbraio et al (1994) suggested that with dehydration and the onset of increased body temperature and elevated plasma epinephrine levels, glycogen utilization increased and thus fatigue onset was quicker.
As mentioned earlier – it is difficult to find specific research into hypohydration. The ones available do offer conflicting findings. Torranin et al (1979) tested 20 males who had either undergone a 4% loss of body weight by sauna exposure or had no sauna exposure and no loss of weight. Isotonic and Isometric tests were conducted and they found both endurance levels were reduced by almost 30%. The problem with this test is that the results could not be solely down to hypohydration as it may well have been the exposure to heat in the sauna that caused these results. Furthermore Greiwe et al (1998) found in 2 separate groups tested (4% weight loss and no weight loss) no significant difference in knee flexor and elbow flexor fatigue.
As ever with science there will be an argument for and against. What I believe we can see is that the onset of dehydration through exercise will have an impact on muscle fatigue as well as our VO2 performance. Hypohydration is another subject matter – while I have read a good amount of data many more are available:
1. Influence of Hypohydration on Intermittent Sprint Performance in the Heat – Neil et al (2009)
2. Hypohydration and muscular fatigue of the thumb alter median nerve somatosensory evoked potentials – Scott, M. J., and William, T. J (2010)
3. Effects of aerobic fitness on hypohydration-induced physiological strain and exercise impairment – Merry et al (2010)
4. Previous-day hypohydration impairs skill performance in elite female field hockey players – MacLeod, H., and Sunderland, C. (2012)
To list but a few…
Cutting weight is a subject matter in itself but I felt that it has clear links to this subject – dehydration. I accept that time lapses from weight in to competing and some people will argue that you can re-hydrate prior to competing. But that could be argued with some research suggesting it takes anything from 4 hours to 48 hours to fully re-hydrate (all dependant on the level of dehydration). It is believed that we absorb water at a rate of roughly 1 litre an hour – the math is simple, if you have cut 2kg in fluid and step on the mat in 45 minutes you are dehydrated. And quite a lot of research suggests you are going to underperform due to muscle fatigue, VO2 impairments while some suggest you will not. And do not forget the effects of loss of electrolytes on our body…. (another blog all together I feel).
Hydration during training is imperative – we all agree. Whether you want to cut weight to compete is up to you, and by doing so through loss of water weight, the gains you feel you are getting through weight advantage may actually not be worth it after all.
Food for thought – or maybe water for thought…. (sorry, terrible pun I know).
Keep rollin oosss
Reference List:
Bardis, C. N., Kavouras, S. A., Arnaoutis, G., Panagiotakos, D. B., and Sidossis, L. S. (2013), ‘Mild Dehydration and Cycling Performance During 5-Kilometer Hill Climbing’, Journal of Athletic Training, Vol. 48, No. 6, pp. 741-747.
Barr, S. I. (1999), ‘Effects of Dehydration on Exercise Performance’, Canadian Journal of Applied Physiology, Vol. 24, No. 2, pp. 164-172
Fabbraio, M. A., Snow, R. J., Hargreaves, M., Stathis, C. G, Martin, I. K., and Carey, M. F. (1994), ‘Muscle Metabolism During Exercise and Heat Stress: Effect of Acclimation’, Journal of Applied Physiology, Vol. 76, pp. 589-597.
Greiwe, J. S., Staffey, K. S., Melrose, D. R., Narve, M. D., and Knowlton, R. G. (1998), ‘Effects of Dehydration on Isometric Muscular Strength and Endurance,’ Medicine and Science in Sports and Exercise, Vol. 30, pp. 284-288
Torranin, C., Smith, D. P., and Byrd, R. J. (1979), ‘The Effect of Acute Thermal Dehydration and Rapid Rehydration on Isometric and Isotonic Endurance’, The Journal of Sport Medicine and Physical Fitness, Vol. 19, pp. 1-9.
Walsh, R.M., Noakes, T. D., Hawley, J. A., and Dennis, S. C. (1994), ‘Impaired High Intensity Cycling Performance Time at Low Levels of Dehydration’, International Journal of Sports Medicine, Vol. 15, No. 7, pp. 392-398.