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The effects of voluntary dehydration on performance and health in combat sports.

Too often in weight categorised sports do we see an athlete aiming to get to a lower weight class or in many cases a coach recommending this, however just because you’re lighter doesn’t mean you’re going to perform any better or that you’ll have an advantage. People can get confused between weight loss and fat loss, body composition (percentages of fat, bone, water and muscle in human bodies) has strong correlation to athlete’s performance. This myth can be seen across many sports, even non-weight categorised sports such as running, which often misconceive being lighter for being faster, however we must remember muscle is a metabolic tissue. (Metabolism is the transformation of food/drink into energy – ATP)

The sports in which I will highlight throughout this article are focused around combat sports as a weight-in is a requirement prior to fights and these sports have shown some extreme weight loss methods/approaches in an effort to make weight, more specific the famous “water-cutting” phase, in which an athlete will voluntarily put themselves into a state of dehydration to achieve a lower weight in a short period of time.


Introduction :  

Voluntary dehydration is the process of entering a state of hypohydration willingly. This is done by causing a negative fluid imbalance where there is a greater fluid loss level than that is replaced or gained, this is normally induced during hot ambient temperatures and exercise. In which a general guideline to ensure euhydration, a normal state of body water content, is for the athlete to weigh their body mass before and after a training session. In which the post workout weight will show a loss of fluids predominantly to be replaced with an electrolyte solution. (I use a rehydration formula of water, glucose and salt for Momentum Performance athletes.)

The process of voluntary dehydration is often seen as a strategy used in weight classified sports such as weightlifting, horse riding, bodybuilding and particularly in combat sports such as taekwondo, judo, ju-jitsu, boxing and mixed martial arts. The common belief of athletes is that the lighter their body mass, the faster they will be and gain a competitive advantage, this is obviously a flawed thought process as they are putting various systems under a lot of strain to cope with such rapid weight loss and then attempting to perform in a contest.

Athletes habitually carry out sudden weight loss strategies in an effort to compete in a lower weight category below their natural or typical weight (Artilo et al 2010, Kinningham & Gorenflo et al 2001). The reasoning behind such an aggressive strategy in relation to the system opposed to a gradual approach is unknown. However, it is speculated that the professional athletes use this approach to strategically achieve their lowest weight possible within a certain time frame (weigh-in) and replenish stores before contest. The negative severity of this strategy is lessened in professional combat sports as there is a greater time gap between weigh-in and contests, typically one or more days, which allows more time to adequately replenish the system.

However, amateur athletes then adapted this approach in which there is a significant reduction in time between weigh in and competition commencement to as little as one hour. The IATBA (Irish athlete third level boxing association) generally have a 2 hour time gap between the last weigh-in and first bout of boxing. Rapid body mass reduction is a frequent practise in combat sport athletes (Wilmore et al, 2000), this may even be evident in competitive children participating in combat sports. Sansone and Sawyer et al 2005, reported such observations in athletes as young as five year old wrestlers. A significant loss of body mass in such restricted time period has been reported in various studies, Artioli et al 2010 reported losses of 5-7% body mass within 5-7 days prior to competition, at times an even greater reduction has been noted. Hall et al 2001, noted a reduction of 5.16% of body weight in amateur boxers within one week of rapid weight loss before competition.

The methods for such intense weight loss varies from athlete to athlete but the most common approaches is to induce a fluid imbalance through manipulation of the thermoregulatory systems (systems of the body to maintain temperature within certain boundaries).

Examples of this are stimulation of hot environments such as saunas and sauna suits (rubber or plastic material made clothing), which reduce the systems mechanisms for cooling such as evaporation. Athletes further force the system to lose fluid by exercising in such environments i.e. jogging in the sauna suit or skipping within the saunas to entice profuse sweat loss.

Athletes have also been reported to have extremely restricted food and fluid intake this in combination with excess sweat loss causes voluntary dehydration and therefore a rapid reduction in body mass within a short time period. This is commonly referred to within combat sports as “cutting water”. Professional athletes, boxing in particular has a notorious reputation for such rapid weight loss approaches are often seen weighing in within the specific weight range and then reportedly having a significant increase in body mass before the contest through hydration and replenishment of stores.

Hypohydration :

Due to this approach such a rapid reduction in body mass, sweat output exceeds water intake and overall results in a negative fluid balance which causes a hypohydrated state. Athletes have been reported to perform below expected performance capabilities during contest in which there is many variables but this has been suggested to be strongly associated with such rapid weight loss strategies.

As athletes enter a hypohydrated state this causes some implications within the cardiovascular system. Plasma volume (liquid component of blood that normally holds the blood cells in whole blood in suspension)  is reduced this causes a decrease in stroke volume (the amount of blood ejected by the heart, more specifically left ventricle, in one contraction) and therefore as a compensatory response there is an increase in heart rate.

This may attribute to an athletes negative impact on RPE (Rate of Perceived Exertion) after “cutting water”. It is also to be noted that sweat loss, is not as what is commonly misconceived to be as just water, there is essential minerals that aid muscle function called electrolytes. These electrolytes can be a variety of substances such as sodium (Na+), Chloride (Cl-) and potassium (K+). Therefore as a result of such acute fluid loss an electrolyte imbalance is likely to occur, this can result in plasma hypertonicity (having a higher osmotic pressure) and hypovolemia (which is too little fluid volume in the blood).

Therefore as a result of hypohydration aerobic exercise tasks can be adversely affected, this negative effect is enhanced in higher exercise intensities. (Sawka et al 2000). Hypohydration reduces cardiac filling (stohr et al 2011) and stroke volume making it challenging to maintain cardiac output and sustain muscle blood flow. It has also been suggested that besides the metabolic restrictions of hypohydration a negative effect can be also seen in relation to psychological profile. Mood has been shown to be an effective predictor of performance in combat sports (Terry et al, 1995). This level of rapid weight loss has been associated with a significantly higher score on anger, fatigue and tense with reduced vigour. Studies have found higher levels of negative mood profiles in athletes involved in weight classified sports.

Hyperthermia :

Heat stress is the physical work and environmental components that combine to create heat load on an individual. It can be assumed that ambient temperature remains constant throughout combat sport contests durations. However, it can alter during the above mentioned simulated hot environments, through exercising in saunas and sauna suits which will prevent efficient heat dissipation mechanisms such as evaporation due to reduced skin blood flow but will increase heat production. The heat stress of the water cutting strategy may impair some thermoregulatory responses the body may utilise to maintain a heat balance, in attempt to keep homeostatic temperature of 37oC within as close a range as possible, this is noted through core temperature. However, a heat imbalance is induced with the water cutting process and this may cause heat injuries as well as health risks such as heat cramps to extreme injuries such as life threatening heat strokes. Heat stress is known to impair submaximal and maximal aerobic exercise performance (Sawka et al 2011). During exercise in heat, the most significant physiological burden is to support high skin blood flow for heat dissipation (Sawka et al 2011), hot skin is associated with reduced cerebral blood flow and oxygen delivery during moderate-intensity exercise such as skipping or jogging in a sauna suit. These simulated heated environment combined with exercise enhances hyperthermia (the condition of having a body temperature greatly above normal) and cardiovascular strain in proportion to the magnitude of body water deficit (Sawka et al 1985).

Performance :

Smith et al 2000 rejected the hypothesis that a rapid dehydration-induced fall in body mass of 4% would have no effect on boxing performance as a mean fall in performance of 26.8% was recorded, this is a potential deciding factor in competition placement. Burge et al 1993, showed results that indicated a reduction in body mass may cause a significant reduction in muscle glycogen concentration (36-54%), this may however be attributed to other factors of the process such as restriction of food intake in particular carbohydrate nutrients, as it is the predominant fuel source for high exercise intensities such as combat sports. This contributes to the decrease in muscle endurance capacity in intermittent intensity exercise. Tippman et al 2008, strongly suggested a reduction within the ranges of 3.3-5.1% in body mass through said processes impairs upper and lower body muscle function during intermittent intensity exercise i.e. combat sport athletes.

Cerebrospinal Fluid :

(a clear, colorless body fluid found in the brain and spine.  It acts as a cushion or buffer for the brain’s cortex, providing basic mechanical and immunological protection to the brain inside the skull. )

One of the main functions of cerebrospinal fluid (CSF) is to protect the brain tissue from injury whenever the head is hit or jolted. If the CSF fails to adequately protect the brain tissue upon impact, for instance a strike during combat sports, the consequences may result in haemorrhaging (in which the usual cause is the brain tissue coming into contact with the skull), brain damage and even death in severe cases, (Streitburger et al 2012).

Neselius et al, 2012 investigated the relationship between Olympic level boxers and CSF brain injury biomarkers. The dangers involved with boxing have been well established within the professional sport, acute traumatic brain injury caused by intracerebral haemorrhage have been reported or repeated mild traumatic brain injury (MTBI), such as concussions, may over time attribute to a more acute brain injury. MTBI can be caused by knock out, in which an athlete loses consciousness or caused by cumulative effect of rotational punches to the head. Severe cases in which there is forceful strikes to the head may result in cortical damage and diffuse axonal injury (DAI) which may eventually lead to a chronic traumatic brain injury. Repetitve head trauma occuring in Olympic boxing may induce changes in CSF even without clinical symptoms of a concussion or TBI. These changes propsose minor central nervous system injuries, it would appear these injuries are recoverable with adequate rest but without such care a cumulative injury may occur.

Strikes to the head is a common in numerous sports, even excluding combat sports such as Rugby, American football, Basketball and Soccer. The risks associated with such sports is well documented in combat sports with many causes of brain injuries being reported overtime. The structural brain changes during dehydration have been investigated by streitburger et al 2012. Dehydration has been shown to reduce volume of CSF within the entire ventricle system, therefore a reduction in protection or cushioning of brain tissue upon impact is evident. This amplifies the risk that those in combat sport are exposed to and makes brain injury more likely whilst dehydrated.

Combat sports by nature are interactive sport where one athletes success and achievement of a victory may be contributed to by the opponents lack of performance, it is possible for an athlete to win a contest despite under performing in relation to respective standard of performance and this is speculated to offset the thinking that such a weight loss strategy has positive effects and often as a result the intense process is repeated.

Conclusion :

To conclude the strategy of rapid reduction in body mass through acute body fluid loss is strongly not recommended and advised to be avoided. The reduction in performance capacity is markedly high, this is due to various components such as reduced glycogen concentrations (36-54%), impaired maximal aerobic capacity (26.8% mean fall in boxing performance), increased negative mood profile (shown to be strongly linked with performance), acute loss of fluids, electrolyte imbalance which causes a reduction in muscle function, hyperthermia which increases heat production and reduced heat loss efficiency.

In terms of health and risks the negative implications of such a gruelling process are markedly evident such as induced heat stress, which may lead to heat exhaustion, cramps and even stroke. Increased risk of brain injury both acute TBI and MTBI through a cumulative of minor injuries. As an overall reduction in CSF is evident, there is a reduced level of protection around the brain tissue. In combat sports strikes to the head are inevitable without relation to magnitude of impact and for an athlete to enter a contest with a reduction in CSF protection while likely to underperform (potentially increasing likelihood of head strikes) is highly dangerous and not recommended. Therefore it is obvious there is no benefit in the voluntary dehydration strategy as a weight loss method for combat sports.

Take home message :

  • Avoid water cutting, a gradual approach to making weight is much better in all aspects of performance and health.
  • Give adequate time to your fight camp, weight loss plan and seek assistance from professionals.
  • Be conscious of the adverse effects and dangers water cutting can have on your health, let alone being dehydrated there is multiple other risks you’re taking which could have very severe consequences.
  • IF YOU MUST, minimise the “water cut” as much as possible, be smart about your rehydration/replenishment approach, it is NOT just water you’re losing.
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