142

BRIEF REVIEW

International Journal of Sports Physiology and Performance, 2017, 12, 142 -151

© 2017 Human Kinetics, Inc.http://dx.doi.org/10.1123/ijspp.2016-0211

Acute-Weight-Loss Strategies for Combat Sports and Applications to Olympic Success

Reid Reale, Gary Slater, and Louise M. Burke

It is common for athletes in weight-category sports to try to gain a theoretical advantage by competing in weight divisions that are lower than their day-to-day body mass (BM). Weight loss is achieved not only through chronic strategies (body-fat losses) but also through acute manipulations before weigh-in (“making weight”). Both have performance implications. This review focuses on Olympic combat sports, noting that the varied nature of regulations surrounding the weigh-in procedures, weight requirements, and recovery opportunities in these sports provide opportunity for a wider discussion of factors that can be applied to other weight-category sports. The authors summarize previous literature that has examined the performance effects of weight-making practices before investigating the physiological nature of these BM losses. Practical recommendations in the form of a decision tree are provided to guide the achievement of acute BM loss while minimizing performance decrements.

Keywords: rapid weight loss, weight cutting, martial arts, weigh-in

Reale and Burke are with the Dept of Sports Nutrition, Australian Inst of Sport, Canberra, ACT, Australia. Slater is with the Dept of Sports Nutri-tion, University of Sunshine Coast, Sippy Downs, QLD, Australia. Address author correspondence to Reid Reale at reid.reale@ausport.gov.au.

In a number of sports, athletes compete in defined weight divisions designed to match competitors according to body mass (BM) as a proxy for body size. This regulation creates a number of unique challenges and practices related to the manipulation of BM around competition that must be integrated into sport-nutrition goals and performance considerations. It is beyond the scope of this review to provide an in-depth commentary on the specific issues in all such sports; however, weight-category sports on the Olympic Games program are of interest. These sports, which feature only at the Summer Games, include rowing, weight lifting, and the majority of combat sports (ie, boxing, tae kwon do, judo, freestyle wrestling, and Greco-Roman wrestling).1 Indeed, at the 2016 Rio Olympic Games, combat sports made up 53 of the 306 available gold medals; consequently, empirically based guidelines focusing on this popula-tion will benefit a large cohort of athletes and support staff.1 The aim of this paper, therefore, was to investigate the specific features of “weight making” in Olympic combat sports. We note that the varied nature of regulations surrounding the weigh-in procedures, weight requirements, and recovery opportunities in these sports will provide opportunity for a wide discussion of factors that can be applied to other weight-category sports.

Weight Categories and Weight LossWeight divisions have been established to create an “even playing field” in which competitors are matched for physical size via BM. Official weigh-ins are held before a competitive event and also on subsequent days in multiday competitions, to certify that athletes have met the requirements of their intended competition division (known as making weight). The duration of the period between weigh-in and competition varies according to the rules of the sport and dictates the opportunity to undertake strategies to recover from

acute-weight-loss (AWL) practices often implemented to achieve the BM target. In the case of boxing, which implements a morning weigh-in, recovery time can range from 3 hours for athletes who fight in the first bouts of the day to 12 hours for competitors in the later bouts. In judo, wrestling, and tae kwon do, weigh-ins held the evening before competition may provide an interval of ~16 hours. These time frames contrast with conditions in the other Olympic weight-category sports (lightweight rowing and weightlifting) in which there is a fixed period of 2 hours between weigh-in and com-petition. Despite the original intention of matching opponents by size, athletes recognize the opportunities provided by the weigh-in format: It is common for fighters to reduce BM using both chronic and acute techniques to qualify for a weight division that is lighter than their “natural” or day-to-day BM, thus gaining a theoretical advantage in size, strength, and/or leverage over smaller opponents. Furthermore, in the Olympic combat sports, where the intervals between the lighter weight divisions are smaller in absolute terms (Table 1), there is a potential temptation for smaller athletes to engage in larger relative AWL. Indeed, there is evidence that those competing in the lighter weight divisions achieve greater relative weight losses than those in heavier weight divisions,2,3 indicating that many athletes intend to compete in the lightest weight division possible.

Professionals who work with these athletes should gain an understanding of current BM-manipulation practices, the physi-ological attributes and consequences of chronic and AWL, and the weigh-in procedures and competition format of Olympic combat sports (Table 2.).

Thorough reviews of the research of weight-loss practices and the effects on health and performance outcomes for athletes have been published in the past, examining chronic and acute strategies in the wider athlete population4 and the specific issue of AWL practices in combat-sport athletes.5 It is clear that both chronic weight-loss and AWL practices are associated with negative outcomes. In terms of chronic practices, the International Olympic Committee recently released a consensus statement detailing the issue of chronic energy deficits in athletes attempting to chronically manage BM and the potential detrimental effects on lean-mass maintenance, immune function, bone health, metabolic rate, and hormonal processes.6

IJSPP Vol. 12, No. 2, 2017

Acute Weight Loss in Combat Sports 143

Table 2 Characteristics of Olympic Combat Sports

Sport Weigh-in procedures Competition format

Freestyle wrestling

Once, evening before competition. All contests for 1 weight division in single day.

Best of 3 × 2-min rounds.

Winner by immobilization of opponent on back (pin) or by judges’ decision via points once time has elapsed.

Greco-Roman wrestling

Once, evening before competition. All contests for 1 weight division in single day.

Best of 3 × 2-min rounds.

Winner by immobilization of opponent on back (pin) or by judges’ decision via points once time has elapsed.

Judo Once, evening before competition.

Additional random weight checks morn-ing of competition, disqualifying those >5% over weight division.

All contests for 1 weight division in single day.

1 × 5-min match.

Winner by ippon (throwing opponent on back with strength, speed, and control; forcing opponent to submit with arm lock or stranglehold; immobilizing opponent on back) or by judges’ decision via points once time has elapsed.

Boxing Morning on the first day of competition and morning of every contest day.

No less than 3 h between weigh-in and contest.

Successive contests on separate days.

2 × 3-min rounds (men); 4 × 2-min rounds (women).

Winner by knockout, technical knockout, referees stoppage, or judges’ decision via points at end of bout.

Tae kwon do Once, evening before competition. All contests for 1 weight division in single day.

3 × 2-min rounds.

Electronic-sensor scoring system.

Winner by knockout, reaching 12-point difference at completion of 2nd round, or superior score at end of bout.

Table 1 Olympic Combat Sports Weight Division (kg)

Freestyle Wrestling Greco-Roman Wrestling Judo Boxing Tae Kwon DoMen’s Women’s Men’s Women’s Men’s Women’s Men’s Women’s Men’s Women’s

<48 <48 46–49 48–51 <49

<53 <52 49–52

<57 <58 <57 52–56 <57

<59 <60 56–60 57–60 <58

<65 <63 <63 60–64

<69 <66 <66 <70 64–69 <68 <67

<74 <75 <75 <73 <78 69–75 69–75 >67

<81 >78 75–81 <80

<86 <85 <90 81–91 >80

>91

<97 <98 <100

>100

<125

<130

Although this statement is applicable to a wide variety of athletes who manipulate their BM and body composition to improve power-to-weight ratios, the unique feature of combat sports (and other weight-category sports) is the superimposition of the AWL phase around competition.

AWL, weight cutting,” or weight making is an ingrained practice in combat sports. Indeed, 1 study reported that its preva-lence is twice as high as the use of gradual weight-loss strategies.7 Combat athletes report that coaches and teammates, as well as

their personal desire to win, are the biggest influences on their decisions regarding weight-loss efforts.8 From their perspective, weight making provides more than a physical advantage over an opponent. Qualitative research indicates that athletes derive a sense of “sport identity” and the feeling of being “real athletes” from the weight-making process.9 Furthermore, it may serve as a coping strategy and create an increased sense of focus and commitment.10 Although the majority of wrestlers believe that making weight is a major activity and important aspect of their sport,10 the equivocal

IJSPP Vol. 12, No. 2, 2017

144 Reale, Slater, and Burke

results of investigations on the benefits on competitive success2,3,11,12 make it difficult to draw conclusions.

In contrast to the real or perceived competitive benefits, many negative consequences may arise from AWL. In November of 1997, 3 American wrestlers died while making weight via food and fluid restriction, the use of vapor impermeable suits, and exercise in a hot and humid environment.13 This prompted rule changes in national competition, including reducing the recovery time post-weigh-in and identifying a minimum wrestling weight (MWW) based on preseason body-composition measurements, which have been asso-ciated with a decline in extreme AWL practices in this cohort.14 Posi-tion statements from the American College of Sports Medicine,15 The Association of Ringside Physicians,16 and the National Athletic Trainers’ Association17 warn against extreme practices and recom-mend rule changes to discourage specific weight-loss techniques and large magnitudes of AWL, as well as recommending minimum body-fat levels of 5% and 12% in males and females, respectively. However, these have yet to influence Olympic competitions, with many athletes who changed their weight-loss practices to suit the new rules for national competitions reverting to previous extreme practices when the rules permit this, as is the case for international-style competitions including the Olympic Games.18

Methods, Prevalence, and Magnitude of AWL

Various methods are used by combat-sport athletes to achieve AWL, with the most popular methods across all Olympic combat sports being an increase in exercise and restriction of fluid and food intake.5,7,14,18,19 Dietary changes include restricted intakes of fluid, carbohydrate, fat, and/or fiber intake with reductions in total energy intake ranging from a 35% decrease during the week before weigh-in to total food restriction on weigh-in day.18–22 Furthermore, it has been demonstrated that athletes who lack a good understanding of nutrition are more likely to resort to extreme fasting and dehydration to achieve weight loss than those with a better understanding.23 The magnitude of AWL before weigh-in is commonly reported at ~5% of BM across all combat athletes5,7,19,21; however, differences exist among sports in the ranges and time spans over which the weight is lost and how frequently they occur.

Performance Implications of AWLThe potential for performance impairment in response to AWL techniques appears obvious, yet the impact of these practices on sport performance remains somewhat an issue of conjecture. While activities that demand high power and strength outputs are less likely to be influenced by AWL,24 performance in activities that require significant contributions of aerobic and anaerobic metabolism to energy yield are typically compromised.4 Several mechanisms have been proposed to explain the implications of AWL on performance. Hypohydration or lowered plasma volume coupled with depletion of muscle glycogen stores has been proposed to underlie the performance decrement associated with AWL.25 However, hypohydration is generally induced in combination with thermal and metabolic stress, and the impact of these confounding variables on performance cannot be discounted. Other mechanisms considered in the literature include changes in enzyme activity, modified sarcoplasmic reticulum function,26 and structural changes to muscles.27 In addition, the body’s acid–base environment may change in response to a significant reduction in dietary carbohydrate

intake.28 Furthermore, psychological performance is adversely influenced by body-water deficits,29 although the impact of this alone on sport-specific performance remains to be addressed. It has also been proposed that hypohydration alters central nervous system function,30 perhaps because of the association between hyperthermia and central fatigue.31 The increase in training load common among athletes attempting to acutely decrease BM may not be without performance implications. A combination of these aforementioned factors may explain the findings in 1 study that reported increased injury rates in athletes inducing AWL >5% BM relative to those practicing less-extreme AWL.32

It is crucial to note, however, that much of the general research on AWL and performance outcomes lacks context validity for weight-making sports. A key shortcoming is the failure to include a recovery period and its associated nutrition practices after the weight-loss period to mimic the interval between weigh-in and the exercise bout in real-world combat sports. Indeed, in studies where ample time and appropriate recovery strategies have followed weigh-in, the acute negative performance effects of AWL have been found to be reversible.33,34

Another real-world aspect of the effect of AWL on performance in combat sports is the recognition that performance is measured relative to other competitors rather than an individual’s absolute best. Thus, it may not be important if AWL reduces an athlete’s performance as long as it remains better than that of an opponent. Several studies have attempted to provide insight into how BM reduction may affect competitive success. In an investigation of high school wrestling,11 where an MWW corresponding to 5% body fat was determined as a voluntary identification of the lowest weight at which an athlete should compete, those competing below MWW were more likely to place in state-championship qualifying tournaments than those who did not.

Another protocol used to examine the real-life relationship between AWL and performance in is to compare the magnitude of the gain in BM between weigh-in and competition and competitive success. This regain of BM has been used as a surrogate for the magnitude of AWL needed to make weight. However, studies that have undertaken this protocol have produced mixed results.2,3,12 For example, it has been reported that large BM regains were correlated with competitive advantage in high school wrestlers3 but not in col-lege wrestlers at a national championship.2 Here it is acknowledged that success in wrestling is determined by multiple factors including aerobic and anaerobic fitness, strength, power, psychological and emotional state, and, perhaps most important, skill and technical proficiency.35 Among high school athletes, where many of these areas are not well developed, BM may contribute more to an athlete’s overall attributes than in more-experienced athletes. However, in the highly selective sporting competition of college wrestling, it is likely that the cohort consisted of a more homogeneous group of already successful athletes. Furthermore, BM regain for winners and losers were substantially higher (5.3% ± 2.0% vs 5.3% ± 2.4% respectively) than in the high school wrestlers (2.4% ± 1.8% vs 1.9% ± 1.6%).

In contrast, no association was found between BM regain and competitive success in teenage tae kwon do athletes,12 which raises physical differences in the activities involved in combat sports as a potential confounder in the importance of BM manipulation. Grap-pling activities, which underpin the sport of wrestling (and judo), involve the manipulation of an opponent’s BM, whereas striking sports (eg, tae kwon do and boxing) are potentially more dependent on the tactical movements of one’s own BM. Indeed, it has been suggested that height plays a more pivotal role than BM in striking

IJSPP Vol. 12, No. 2, 2017

Acute Weight Loss in Combat Sports 145

sports and that athletes should be separated by height rather than BM to equalize competition matchups.36 Unfortunately, there are no studies on the effect of post-weigh-in BM regain on competitive success in judo or boxing.

In summary, the final effect of AWL on combat-sport per-formance involves a complex interaction of factors including the method of AWL; the intensity, type, and duration of the performance effort; environmental conditions; and an individual’s fitness capac-ity.26 Furthermore, the rules of the sport, including the period of time between weigh-in and competition, allow an opportunity for athletes to restore fluid deficits and replace carbohydrate stores, which may have been manipulated before weigh-in, and thus recalibrate the final performance effect. This will now be explored.

Recovery Practices After AWLAlthough combat-sport athletes recognize the importance of replac-ing fuel stores and restoring fluid deficits post-weigh-in, many do not appear to follow best-practice guidelines.37 The optimal recov-ery strategy will depend on the methods of AWL that were used. Recovery from the dehydration associated with AWL is possible depending on the degree of fluid loss and the recovery time avail-able. In the laboratory setting dehydration of 2.8% and changes in plasma volume are reversible after 3 hours of aggressive nutritional recovery.38 However, in 1 example during an actual wrestling competition, plasma-volume and body-water changes associated with dehydration of 6% BM were not completely reversed even 15 hours post-weigh-in.39 Indeed, hydration assessment undertaken just before competition revealed significant levels of hypohydration in more than 80% and 95% of combat-sport athletes who participated in events with weigh-ins scheduled for the evening before and the morning of the event, respectively.40

In terms of restoration or preparation of glycogen stores before competition, an assessment of the dietary practices of wrestlers after a weigh-in on the evening before competition found that reported carbohydrate intake was in general agreement with guidelines for optimal glycogen storage.41 A different study using muscle glycogen measurement via biopsy techniques confirmed the general success of athletes in preparing adequate fuel stores for competition when overnight recovery was available.42 It is unclear whether athletes who undergo weigh-in the morning of a competition can fully nor-malize or supercompensate muscle glycogen levels; however, such targets may not be necessary for optimal performance. Indeed, 4 hours of refueling has been shown to be adequate for judo-related performance,43 and glycogen stores have not be found to be limiting for performance when ad libitum intake of carbohydrate between bouts is allowed.42 Thus, aggressive refueling strategies involving the intake of large amounts of carbohydrate between weigh-in and competition may not be warranted.

Taken together, the apparent post-weigh-in fluid- and food-intake practices of combat athletes and the theoretical timelines of glycogen storage and rehydration allow the following conclusions. For combat sports that implement weigh-ins the evening before competition, there is opportunity for adequate restoration of fluid and fuel status; furthermore, although this is probably achieved in the case of glycogen preparation, many athletes do not attain euhy-dration.37,40,42 In contrast, shorter recovery periods, as occur when weigh-in occurs on the morning of competition, do not provide enough time for athletes to rehydrate when they have employed dehydration to the degree commonly practiced.4,5,40,44 Furthermore, while theoretically providing enough time for sufficient (not full) glycogen restoration,42 the period between a morning weigh-in and

competition may not be well used by athletes.37 All of these findings highlight the importance of appropriate nutrition education for both coaches and athletes. Providing detailed recommendations is beyond the scope of this review; thus readers are directed to published reviews on rehydration45 and glycogen restoration.46

Understanding the Physiology of AWLDuring the process of AWL, BM is lost from various compartments of the body, with measurement artifacts sometimes obscuring the real shifts and losses involved. A small amount of body fat is lost as a result of several days of energy restriction,47,48 but significant reductions in measurements of lean mass are also observed.47,49 Changes in lean-mass measurements associated with restriction of energy, carbohydrate, and fluid appear to be essentially reversed after post-weigh-in recovery or postcompetition. This suggests they are associated with loss of muscle water and substrates (eg, glycogen) rather than loss of contractile proteins. This theory is supported by evidence of reductions in total body water with weight making49 and a halving of biopsy-derived values of muscle glycogen during a 72-hour AWL protocol where there was a loss of 5% BM.42 A significant reduction in the intake of dietary fiber and total food mass associated with food restriction20,37,50 is also likely to cause a loss of BM as a consequence of reduced gastrointestinal contents and fluid in the intestinal lumen bound to dietary fiber.51 This section will address each of these potential areas of BM change during AWL, with the intent of understanding how they can be best manipulated to minimize health risks and optimize performance.

Overview of Body Water and AWL

Water makes up about 60% of the human body52; this varies within and between different population types and is likely to be higher in combat-sport athletes due to their relatively high levels of lean mass.35 Given the size of this body compartment and the speed and ease of its manipulation in comparison with other contributors to BM, it is logical that it is a primary focus of the AWL strategies of combat-sport athletes.

There are 3 separate strategies that can be used to achieve an acute reduction in body-water content: the consumption of less fluid (fluid restriction) in relation to normal daily losses, the “unlocking” of bound body fluid that will in turn be excreted, and the promotion of additional fluid loss. Fluid restriction is an obvious means to reduce total body water and plays a well-documented role in the AWL practices of combat athletes.18–22 Reductions in fluid compartments in the body can be derived from losses from both intracellular and extracellular stores and include free or bound water. Bound water, which has the potential to be eliminated, includes that in glycogen stores and also that drawn into the intestinal space due to the presence of food matter with absorptive properties, such as fiber-containing foods. The excretion of water from the body is accomplished via respiration, urination, and perspiration (sweating).

Respiration and Water Loss. Respiratory water losses are affected by pulmonary ventilation, plus the temperature and humidity of inspired air. In temperate environments, these losses are approxi-mately equal to the amount of water generated through aerobic metabolism, roughly 250 to 350 mL/d, increasing with respiratory rate as exercise intensity increases.52 While altitude does not signifi-cantly alter respiratory water losses,53 large decreases in humidity (from 80% to 20%) can dramatically affect respiratory water losses,

IJSPP Vol. 12, No. 2, 2017

146 Reale, Slater, and Burke

particularly during exercise where losses increase from 0.8 to 2.7 mL/min.54 Oral exhalation increases net respiratory water losses by up to 46% compared with nasal exhalation.55

It should be noted that some bound water is released during aerobic metabolism and expelled via respiration52; however, the ability to acutely manipulate this type of bound water is minimal, and the minor amount (relative to other paths of fluid loss) can essentially be disregarded in the context of AWL. Total daily respi-ratory water losses range from 400 mL/d in sedentary individuals in temperate environments to 1500 mL/d during times of exercise in low humidity.54 In terms of AWL strategies, exposure to a low-humidity environment in the days before weigh-in provides a passive method to significantly increase water losses, while exercising in this environment allows the addition of increased insensible loss to sweat losses.

Urination and Water Loss. Urine production is the body’s pri-mary method of regulating fluid balance. This process is tightly controlled by the renal system, with aldosterone and antidiuretic hormone triggering renal responses to conserve or release fluid and sodium, thus maintaining body water and plasma sodium concentration. Depending on other contributions to body-fluid balance, typical daily urine losses are in the range of 1 to 2 L/d52,54 but significantly decrease as dehydration progresses.56 Obligatory rates of urine production to allow the elimination of body-waste products are 0.5 L/d and, thus, set the low level of the range of daily losses, while fluid intakes greater than the maximal rate of urine production of 18 L can lead to hyponatremia/water intoxica-tion.57,58 Encouraging polyuria against the tide of hydration status presents another strategy of AWL, with protocols including sleeping or lying with the head tilted downward59 and acute intake of high doses of vitamin C.60 Mechanisms underpinning the increased urine production in the former relate to disturbances in fluid and sodium homeostatic regulators caused by prompt increases in central blood volume.59

Combat-sport athletes have been reported to use pharmacologi-cal diuretics to promote greater urine loss, in spite of their inclusion on the World Anti-Doping Agency’s list of prohibited substances.5,21 Herbal diuretics that have been shown to be effective in facilitat-ing polyuria61 may also be used, although this activity is morally questionable with respect to doping and may result in performance decrements due to preferential plasma volume losses, as is the case for their pharmacological counterparts.62

One novel but largely untested method reportedly used by combat-sport athletes to increase urine production is the process of water loading.63 Anecdotally, it is claimed that excessive water intake over a few days promotes polyuria that persists beyond the period of increased fluid intake and thus achieves a net decrease in body water.64 This remains to be confirmed through scientific inves-tigation but, if successful, could provide an effective means of fluid loss, albeit with the potential side-effect of promoting the potentially dangerous outcome of hyponatremia via water intoxication.58

Sweating and Water Loss. Although urination may account for the majority of fluid losses in the general population in temperate environments, in hot and/or humid environments, perspiration (or loss of sweat) associated with thermoregulatory activities accounts for the majority of fluid losses.52 Furthermore, in all environments, the thermal challenge provided by exercise increases sweat losses, with a range of sweat rates being observed across individuals, exercise protocols, and environmental conditions.52

The facilitation of body-fluid loss via sweating can include active (exercise-induced) or passive (exposure to hot environment)

strategies and is the most common method of acute BM manipula-tion undertaken by combat-sport athletes.5,19,21 This observation is not surprising since sweat rates of up to 2 L/h can be achieved and represent a rapid way to achieve relative large BM losses.52

Body sweat response is driven by a number of factors including core temperature and skin temperature. The onset of sweating can be altered by changes in plasma electrolyte concentration, plasma volume, and total body-water content; however, these cannot be manipulated to enhance sweat losses without the introduction of more fluid into the body, which is counterproductive to the goal of AWL.65 However, heat acclimation, adaption to exercise train-ing, and increased skin temperature are useful in increasing sweat losses.65 It should be noted, however, that females produce less sweat than males and are less responsive to the effects of training adap-tion on sweat rate and sweat temperature threshold.66 This has been attributed to hormonal and peripheral vasodilation differences.66

It is important to note the differences in physiological response to passive versus active sweating. Passive sweating before exercise decreases plasma volume, sweat rate, and stroke volume during exercise, contributing to an increase in serum osmolality, heart rate, and body-heat storage. These physiological changes occur to a lesser extent when hypohydration develops only during exercise.67 Thus, a combination of fluid restriction and active dehydration may be the most practical way to induce dehydration to acutely reduce BM while minimizing performance decrements. Athletes should make use of existing training sessions to promote active dehydra-tion in preference to additional “sweat training.” Further passive sweating should be used only when necessary and when ample time is available for recovery. If using saunas as means to facilitate perspiration, dry-heat saunas should be used in preference to steam saunas, as it has been demonstrated that fluid loss for a given period of time is greater (up to double the rate of loss) and results in less physiological strain.68

Sodium Intake and Water Loss. The human body tightly regu-lates the osmotic pressure of body fluids through renal excretion and retention of electrolytes and fluid. It is commonly accepted that increased sodium intake leads to increased fluid retention and that the reverse is true also.45,52 This explains the common health guideline to lower sodium intake to lower blood volume and, thus, blood pressure. In 1 study, hypertensive subjects lost 1% to 2% BM after following a low-sodium diet (<500 mg) for 5 days, although no interim measures were taken to establish the time frame of weight reduction.69 While a reduction in salt intake has been shown to significantly reduce blood pressure in hypertensive people and to a lesser extent in normotensive people,70 indicating a decrease in intravascular fluid retention, this may not translate to alterations in BM in all people. Nevertheless, it has become a practice of some combat-sport athletes to reduce sodium below habitual intakes during the weight-cutting period.20 While this may not influence total body water per se, when used in combination with other fluid-manipulation strategies it may release more body water and allow a reduction in BM. This remains to be confirmed by empirical research.

Glycogen, Bound Water, and AWL. Dietary carbohydrate is stored in skeletal muscle and liver tissue as glycogen and acts as an energy reserve that can be quickly mobilized when there is a need for glucose. Glycogen is a branched biopolymer of glucose that has been noted to bind to water at a ratio of 1:2.7 (water:glycogen).71 Furthermore, glycogen storage may contribute up to 8% of liver weight and 1% to 2% of skeletal-muscle weight.72,73 Thus, based on calculation of the male body being 60% to 65% muscle

IJSPP Vol. 12, No. 2, 2017

Acute Weight Loss in Combat Sports 147

mass74 with an average liver weight of 1.56 kg,75 a 75-kg male may potentially store 462 g and 1665 to 3610 g of glycogen and bound water in the liver and skeletal muscle, respectively. Of course the validity of these estimations is limited by the accuracy of measurements of glycogen:water ratios and the stability of this ratio in different tissues and across different glycogen concentra-tions.54 Nevertheless, manipulation of glycogen stores provides another strategy for athletes to obtain AWL. Two methods are available to achieve this: to consume a low-carbohydrate diet to prevent the restoration of muscle glycogen stores after their depletion via the normal training program and to perform addi-tional exercise to deplete glycogen reserves more rapidly. Issues determining the benefits and disadvantages of each approach include the effects of additional exercise in the period just before the weigh-in or event versus the effect of a more chronic period of carbohydrate depletion on programmed training leading into the competition.

Data from the available literature show that 7 days of a low-carbohydrate diet, combined with training and a slight reduction in energy (<10%), can achieve a BM reduction of ~2% while maintain-ing performance of strength and power measures and a 30-second Wingate test.76 Similar findings have been demonstrated by others after following a low-carbohydrate diet for 2 weeks.77 However, 6 weeks of a low-carbohydrate diet was associated with increased rating of perceived exertion during exercise and decrements in power and endurance, which the authors attributed to losses in lean mass.78 Together, these findings have several implications for combat-sport athletes:

• The adoption of a low-carbohydrate diet is an effective means to decrease BM to make weight (via the loss of glycogen and bound water).

• It may not be crucial to replenish glycogen stores when the recovery period between weigh-in and competition is minimal.

• A viable weight-making strategy for sports with multiple weigh-ins across consecutive days (ie, amateur boxing) may involve the reduction of BM via a low-carbohydrate diet before the first weigh-in, with the maintenance of this strategy over the course of the competition period and opportunities for acute rehydration and intake of adequate carbohydrate for each bout.

The magnitude of possible BM loss and the strategies needed to achieve it (ie, the level of carbohydrate restriction and the time required to produce maximal BM loss) will depend on glycogen status and training load before commencement of the strategy. Restricting carbohydrate intake to less than 50 g/d (combined with a small reduction in energy) should be enough to facilitate 1% to 2% BM loss based on existing research76 and the reported carbohydrate intakes of combat-sport athletes.20,50

Gut Contents and AWL

Many fighters have been reported to reduce portion sizes and total food volume before weigh-in to reduce mass of intestinal contents and contribute to total loss of BM.18–22 The use of bowel-preparation formulas (used in clinical situations to prepare for gut surgery) or laxatives is not uncommon among weight-category-sport athletes, presumably to facilitate the expulsion of intestinal contents and promotion of AWL, possibly equating to 1 kg.79 The prevalence of laxative use and/or vomiting has been reported to be around 10% in combat-sport athletes.21,80 While these methods may be effective in cleansing the colon and removing intestinal bulk, the specific use of bowel-preparation formulas (typically

containing osmotic laxatives and purgatives) has been shown to reduce exercise capacity.79 Therefore, dietary strategies to reduce total food volume may be a preferable way to manipulate the mass of intestinal contents while maintaining performance goals. This might include a switch to consumption of foods that are energy dense in the hours and days before weigh-in to maintain energy and macronutrient intakes with a smaller food mass. This would be particularly important for those whose weigh-in times are within several hours of competition time and who thus have limited potential to effectively rehydrate and refuel between weigh-in and competition.

Dietary fiber can both slow transit time of foods through the bowel and draw water into the intestinal space, adding bulk to stools. Different foods have different fecal-bulking properties,51 but it is assumed that if a person reduces his or her habitual consumption of “bulking” fiber-rich foods, it will reduce the mass of undigested plant matter, the amount of water drawn into the intestinal space, and fecal bulk, favorably lowering BM. Indeed, a linear relationship exists between fiber intake and bowel cleanliness in precolonoscopy patients,81 and the adoption of a low-fiber diet for even 2 days helps cleanse the bowel (relative to higher-fiber diets),81 with 7 days of <10 g fiber per day being as effective as a protocol involving a bowel-preparation formula (Selg 1000, Promefarm, Milan, Italy).82 In addition, low-fiber diets result in less physiological stress and symptoms than bowel-preparation formulas.82 For combat-sport ath-letes, the ability to continue to train throughout the bowel-emptying process is an important consideration.

Despite the available research on the bowel-emptying effects of low-fiber diets and the evidence that many fighters adopt low-fiber diets during the final days before weigh-in,20 there are no specific investigations on the success of this approach on the outcomes of weight making and the magnitude of the weight change it might achieve. In addition, since whole-gut transit times vary widely between individuals from 10 to 96 hours,83 precise guidelines for the use of fiber restriction for AWL cannot be determined at this stage. Further investigation in the application of low-residue formulas to weight making is warranted, including the potential for weight loss, along with health and performance implications.

Conclusion and Practical ApplicationsAthletes currently engage in varying degrees of fluid deprivation, food restriction, and increased exercise in protocols aimed at achieving AWL. In light of the information discussed in this review, recommendations can be devised to refine weight-making practices of combat-sport athletes. While some form of dietary restriction is generally necessary to facilitate AWL, the most effective strategy to achieve AWL while allowing restoration of performance after the weigh-in is to consume strategic amounts of energy from low-weight, low-fiber foods while inducing a mild fluid deficit. Greater fluid deficits and depletion of glycogen stores provide an additional strategy for those requiring greater weight losses. Optimal post-weigh-in recovery strategies are influenced by the methods used to achieve AWL. Figure 1 provides a decision tree to help coaches and athletes plan an appropriate weight-making strategy.

It is important to note that circumstances will vary between sports and individuals. By monitoring day-to-day and within-day fluctuations in BM, athletes and coaches can better understand the acute management of BM. Athletes should trial their weight-making and recovery practices before important competitions, record their experiences, and continually reflect on the process from 1 weigh-in to the next.

148 IJSPP Vol. 12, No. 2, 2017

Figure 1 — Weight-making-plan decision tree.

IJSPP Vol. 12, No. 2, 2017

Acute Weight Loss in Combat Sports 149

References 1. International Olympic Committee. International Olympic Committee

Web site. 2016. Available at: https://www.olympic.org/sports. 2. Horswill CA, Scott JR, Dick RW, Hayes J. Influence of rapid weight

gain after the weigh-in on success in collegiate wrestlers. Med Sci Sports Exerc. 1994;26(10):1290–1294. PubMed doi:10.1249/00005768-199410000-00018

3. Wroble RR, Moxley DP. Acute weight gain and its relationship to suc-cess in high school wrestlers. Med Sci Sports Exerc. 1998;30(6):949–951. PubMed

4. Fogelholm M. Effects of bodyweight reduction on sports performance. Sports Med. 1994;18(4):249–267. PubMed doi:10.2165/00007256-199418040-00004

5. Franchini E, Brito CJ, Artioli GG. Weight loss in combat sports: physi-ological, psychological and performance effects. J Int Soc Sports Nutr. 2012;9(1):52. PubMed doi:10.1186/1550-2783-9-52

6. Mountjoy M, et al. The IOC consensus statement: beyond the female athlete triad—relative energy deficiency in sport (RED-S). Br J Sports Med. 2014;48(7):491–497. PubMed doi:10.1136/bjsports-2014-093502

7. Kordi R, et al. Patterns of weight loss and supplement consumption of male wrestlers in Tehran. Sports Med Arthrosc Rehabil Ther Technol. 2011;3(1):4. PubMed doi:10.1186/1758-2555-3-4

8. Marquart LF, Sobal J. Weight loss beliefs, practices and support sys-tems for high school wrestlers. J Adolesc Health. 1994;15(5):410–415. PubMed doi:10.1016/1054-139X(94)90266-6

9. Pettersson S, Ekström MP, Berg CM. Practices of weight regulation among elite athletes in combat sports: a matter of mental advantage? J Athl Train. 2013;48(1):99–108. PubMed

10. Oppliger RA, et al. Bulimic behaviors among interscholastic wrestlers: a statewide survey. Pediatrics. 1993;91(4):826–831. PubMed

11. Wroble RR, Moxley DP. Weight loss patterns and success rates in high school wrestlers. Med Sci Sports Exerc. 1998;30(4):625–628. PubMed doi:10.1097/00005768-199804000-00022

12. Kazemi M, Rahman A, De Ciantis M. Weight cycling in adolescent Taekwondo athletes. J Can Chiropr Assoc. 2011;55(4):318–324. PubMed

13. Centers for Disease Control and Prevention. Hyperthermia and dehydration-related deaths associated with intentional rapid weight loss in three collegiate wrestlers—North Carolina, Wisconsin, and Michigan, November–December 1997. MMWR Morb Mortal Wkly Rep. 1998;47(6):105–108. PubMed

14. Oppliger RA, Steen SAN, Scott JR. Weight loss practices of college wrestlers. Int J Sport Nutr Exerc Metab. 2003;13(1):29–46. PubMed doi:10.1123/ijsnem.13.1.29

15. Oppliger RA, et al. American College of Sports Medicine position stand: weight loss in wrestlers. Med Sci Sports Exerc. 1996;28(6):ix–xii. PubMed

16. Association of Ringside Physicians. Consensus statement on weight management in professional combat sports. 2014. Available at: http://www.ringsidearp.org/resources/Documents/Position%20Statements/Weight%20Management%20in%20Professional%20Combat%20Sports.pdf.

17. Turocy PS, et al. National Athletic Trainers’ Association position state-ment: safe weight loss and maintenance practices in sport and exercise. J Athl Train. 2011;46(3):322–336. PubMed

18. Alderman B, et al. Factors related to rapid weight loss practices among international-style wrestlers. Med Sci Sports Exerc. 2004;36(2):249–252. PubMed doi:10.1249/01.MSS.0000113668.03443.66

19. Brito CJ, et al. Methods of body-mass reduction by combat sport athletes. Int J Sport Nutr Exerc Metab. 2012;22(2):89–97. PubMed doi:10.1123/ijsnem.22.2.89

20. Fleming S, Costarelli V. Nutrient intake and body composition in relation to making weight in young male Taekwondo players. Nutr Food Sci. 2007;37(5):358–366. doi:10.1108/00346650710828389

21. Artioli GG, et al. Prevalence, magnitude, and methods of rapid weight loss among judo competitors. Med Sci Sports Exerc. 2010;42(3):436–442. PubMed doi:10.1249/MSS.0b013e3181ba8055

22. Kiningham RB, Gorenflo DW. Weight loss methods of high school wrestlers. Med Sci Sports Exerc. 2001;33(5):810–813. PubMed doi:10.1097/00005768-200105000-00021

23. Steen SN, McKinney S. Nutrition assessment of college wrestlers. Physician Sportsmed. 1986;14(1):100–105, 108–109, 112, 115–116. doi:10.1080/00913847.1986.11709226

24. Greiwe JS, et al. Effects of dehydration on isometric muscular strength and endurance. Med Sci Sports Exerc. 1998;30(2):284–288. PubMed doi:10.1097/00005768-199802000-00017

25. Burge CM, Carey MF, Payne WR. Rowing performance, fluid balance, and metabolic function following dehydration and rehy-dration. Med Sci Sports Exerc. 1993;25(12):1358–1364. PubMed doi:10.1249/00005768-199312000-00007

26. Fitts RH. Cellular mechanisms of muscle fatigue. Physiol Rev. 1994;74(1):49–94. PubMed

27. Walberg-Rankin J. Changing body weight and composition in ath-letes. In: Lamb DR, Murray R, eds. Exercise, Nutrition and Weight Control. Carmel, IN: Cooper; 1998:199–242.

28. Greenhaff PL, Gleeson M, Maughan RJ. Diet-induced metabolic acidosis and the performance of high intensity exercise in man. Eur J Appl Physiol Occup Physiol. 1988;57(5):583–590. PubMed doi:10.1007/BF00418466

29. Filaire E, et al. Food restriction, performance, psychological state and lipid values in judo athletes. Int J Sports Med. 2001;22(6):454–459. PubMed doi:10.1055/s-2001-16244

30. Montain SJ, et al. Hypohydration effects on skeletal muscle per-formance and metabolism: a 31P-MRS study. J Appl Physiol. 1998;84(6):1889–1894. PubMed

31. Nybo L, Nielsen B. Hyperthermia and central fatigue during pro-longed exercise in humans. J Appl Physiol. 2001;91(3):1055–1060. PubMed

32. Green CM, et al. Injuries among judokas during competition. Scand J Med Sci Sports. 2007;17(3):205–210. PubMed

33. Koral J, Dosseville F. Combination of gradual and rapid weight loss: effects on physical performance and psychological state of elite judo athletes. J Sports Sci. 2009;27(2):115–120. PubMed doi:10.1080/02640410802413214

34. Mendes SH, et al. Effect of rapid weight loss on performance in combat sport male athletes: does adaptation to chronic weight cycling play a role? Br J Sports Med. 2013;47(18):1155–1160. PubMed doi:10.1136/bjsports-2013-092689

35. Horswill CA. Applied physiology of amateur wrestling. Sports Med. 1992;14(2):114–143. PubMed doi:10.2165/00007256-199214020-00004

36. Dubnov-Raz G, et al. Can height categories replace weight categories in striking martial arts competitions?: a pilot study. J Hum Kinet. 2015;47:91–98. PubMed doi:10.1515/hukin-2015-0065

37. Pettersson S, Berg CM. Dietary intake at competition in elite Olympic combat sports. Int J Sport Nutr Exerc Metab. 2014;24(1):98–109. PubMed doi:10.1123/ijsnem.2013-0041

38. Smith M, et al. The effects of dehydration and subsequent rehydra-tion on amateur boxing performance. J Sports Sci. 1996;14(4):366.

39. Yankanich J, et al. Precompetition weight loss and changes in vas-cular fluid volume in NCAA Division I college wrestlers. J Strength Cond Res. 1998;12(3):138–145.

IJSPP Vol. 12, No. 2, 2017

150 Reale, Slater, and Burke

40. Pettersson S, Berg CM. Hydration status in elite wrestlers, judokas, boxers, and taekwondo athletes on competition day. Int J Sport Nutr Exerc Metab. 2014;24(3):267–275. PubMed doi:10.1123/ijsnem.2013-0100

41. Lambert C, Jones B. Alternatives to rapid weight loss in US wrestling. Int J Sports Med. 2010;31(8):523–528. PubMed doi:10.1055/s-0030-1254177

42. Tarnopolsky MA, et al. Effects of rapid weight loss and wrestling on muscle glycogen concentration. Clin J Sport Med. 1996;6(2):78–84. PubMed doi:10.1097/00042752-199604000-00003

43. Artioli GG, et al. Rapid weight loss followed by recovery time does not affect judo-related performance. J Sports Sci. 2010;28(1):21–32. PubMed doi:10.1080/02640410903428574

44. Lingor RJ, Olson A. Fluid and diet patterns associated with weight cycling and changes in body composition assessed by continuous monitoring throughout a college wrestling season. J Strength Cond Res. 2010;24(7):1763–1772. PubMed doi:10.1519/JSC.0b013e3181db22fb

45. Shirreffs SM, Sawka MN. Fluid and electrolyte needs for training, competition, and recovery. J Sports Sci. 2011;29(Suppl 1):S39–S46. PubMed doi:10.1080/02640414.2011.614269

46. Beelen M, et al. Nutritional strategies to promote postexercise recov-ery. Int J Sport Nutr Exerc Metab. 2010;20(6):515–532. PubMed doi:10.1123/ijsnem.20.6.515

47. Finaud J, et al. Competition and food restriction effects on oxida-tive stress in judo. Int J Sports Med. 2006;27(10):834–841. PubMed doi:10.1055/s-2005-872966

48. Yanagawa Y, et al. Oxidative stress associated with rapid weight reduction decreases circulating adiponectin concentrations. Endocr J. 2010;57(4):339–345. PubMed doi:10.1507/endocrj.K09E-359

49. Jlid MC, et al. Rapid weight loss alters muscular performance and perceived exertion as well as postural control in elite wrestlers. J Sports Med Phys Fitness. 2013;53(6):620–627. PubMed

50. Boisseau N, Vera-Perez S, Poortmans J. Food and fluid intakes in female adolescent judo athletes before competition. Pediatr Exerc Sci. 2005;17(1):62–71. doi:10.1123/pes.17.1.62

51. Monro JA. Faecal bulking index: a physiological basis for dietary management of bulk in the distal colon. Asia Pac J Clin Nutr. 2000;9(2):74–81. PubMed doi:10.1046/j.1440-6047.2000.00155.x

52. Sawka MN, Cheuvront SN, Carter Iii R. Human water needs. Nutr Rev. 2005;63:S30–S39. PubMed doi:10.1111/j.1753-4887.2005.tb00152.x

53. Westerterp KR, et al. Operation Everest III: energy and water balance. Pfluegers Arch. 2000;439(4):483–488. doi:10.1007/s004249900203

54. Maughan RJ, Shirreffs SM, Leiper JB. Errors in the estimation of hydration status from changes in body mass. J Sports Sci. 2007;25(7):797–804. PubMed doi:10.1080/02640410600875143

55. Svensson S, Olin AC, Hellgren J. Increased net water loss by oral compared to nasal expiration in healthy subjects. Rhinology. 2006;44(1):74–77. PubMed

56. Pross N, et al. Influence of progressive fluid restriction on mood and physiological markers of dehydration in women. Br J Nutr. 2013;109(2):313–321. PubMed doi:10.1017/S0007114512001080

57. Robertson GL, Norgaard JP. Renal regulation of urine volume: potential implications for nocturia. BJU Int. 2002;90:7–10. PubMed doi:10.1046/j.1464-410X.90.s3.2.x

58. Adrogué HJ, Madias NE. Hyponatremia. N Engl J Med. 2000;342(21):1581–1589. PubMed doi:10.1056/NEJM200005253422107

59. Norsk P, et al. Volume-homeostatic mechanisms in humans during a 12-h posture change. J Appl Physiol. 1993;75(1):349–356. PubMed

60. Abbasy MA. The diuretic action of vitamin C. Biochem J. 1937;31(2):339–342. PubMed doi:10.1042/bj0310339

61. Clare BA, Conroy RS, Spelman K. The diuretic effect in human sub-jects of an extract of Taraxacum officinale folium over a single day. J Altern Complement Med. 2009;15(8):929–934. PubMed doi:10.1089/acm.2008.0152

62. Caldwell JE, Ahonen E, Nousiainen U. Differential effects of sauna-, diuretic-, and exercise-induced hypohydration. J Appl Physiol. 1984;57(4):1018–1023. PubMed

63. Crighton B, Close GL, Morton JP. Alarming weight cutting behav-iours in mixed martial arts: a cause for concern and a call for action. Br J Sports Med. 2016;50(8):446–447. PubMed doi:10.1136/bjs-ports-2015-094732

64. Kobilansky G. How to cut weight the right way. 2015. Available at: http://breakingmuscle.com/mma/how-to-cut-weight-the-right-way.

65. Shibasaki M, Wilson TE, Crandall CG. Neural control and mecha-nisms of eccrine sweating during heat stress and exercise. J Appl Physiol. 2006;100(5):1692–1701. PubMed doi:10.1152/jap-plphysiol.01124.2005

66. Ichinose-Kuwahara T, et al. Sex differences in the effects of physi-cal training on sweat gland responses during a graded exercise. Exp Physiol. 2010;95(10):1026–1032. PubMed doi:10.1113/exp-physiol.2010.053710

67. Walsh RM, et al. Impaired high-intensity cycling performance time at low levels of dehydration. Int J Sports Med. 1994;15(7):392–398. PubMed doi:10.1055/s-2007-1021076

68. Pilch W, et al. Comparison of physiological reactions and physiologi-cal strain in healthy men under heat stress in dry and steam saunas. Biol Sport. 2014;31(2):145–149. PubMed doi:10.5604/20831862.1099045

69. He FJ, et al. Effect of salt intake on renal excretion of water in humans. Hypertension. 2001;38(3):317–320. PubMed doi:10.1161/01.HYP.38.3.317

70. Cutler JA, Follmann D, Allender PS. Randomized trials of sodium reduction: an overview. Am J Clin Nutr. 1997;65(2):643S–651S. PubMed

71. Bergström J, Hultman E. Nutrition for maximal sports perfor-mance. JAMA. 1972;221(9):999–1006. PubMed doi:10.1001/jama.1972.03200220033009

72. Nilsson LH. Liver glycogen content in man in the postabsorp-tive state. Scand J Clin Lab Invest. 1973;32(4):317–323. PubMed doi:10.3109/00365517309084354

73. Hultman E. Muscle glycogen in man determined in needle biopsy specimens method and normal values. Scand J Clin Lab Invest. 1967;19(3):209–217. PubMed doi:10.3109/00365516709090628

74. Spenst LF, Martin AD, Drinkwater DT. Muscle mass of com-petitive male athletes. J Sports Sci. 1993;11(1):3–8. PubMed doi:10.1080/02640419308729956

75. Molina DK, DiMaio VJM. Normal organ weights in men: part II—the brain, lungs, liver, spleen, and kidneys. Am J Forensic Med Pathol. 2012;33(4):368–372. PubMed doi:10.1097/PAF.0b013e31823d29ad

76. Sawyer JC, et al. Effects of a short-term carbohydrate-restricted diet on strength and power performance. J Strength Cond Res . 2013;27(8):2255–2262. PubMed doi:10.1519/JSC.0b013e31827da314

77. Lambert EV, et al. Enhanced endurance in trained cyclists during moderate intensity exercise following 2 weeks adaptation to a high fat diet. Eur J Appl Physiol Occup Physiol. 1994;69(4):287–293. PubMed doi:10.1007/BF00392032

78. Fleming J, et al. Endurance capacity and high-intensity exercise per-formance responses to a high-fat diet. Int J Sport Nutr Exerc Metab. 2003;13(4):466–478. PubMed doi:10.1123/ijsnem.13.4.466

79. Holte K, et al. Physiologic effects of bowel preparation. Dis Colon Rectum. 2004;47(8):1397–1402. PubMed doi:10.1007/s10350-004-0592-1

IJSPP Vol. 12, No. 2, 2017

Acute Weight Loss in Combat Sports 151

80. Filaire E, et al. Eating attitudes, perfectionism and body-esteem of elite male judoists and cyclists. J Sports Sci Med. 2007;6(1):50–57. PubMed

81. Wu K-L, et al. Impact of low-residue diet on bowel preparation for colo-noscopy. Dis Colon Rectum. 2011;54(1):107–112. PubMed doi:10.1007/ DCR.0b013e3181fb1e52

82. Lijoi D, et al. Bowel preparation before laparoscopic gynaecological surgery in benign conditions using a 1-week low fibre diet: a sur-

geon blind, randomized and controlled trial. Arch Gynecol Obstet. 2009;280(5):713–718. PubMed doi:10.1007/s00404-009-0986-3

83. Lee YY, Erdogan A, Rao SSC. How to assess regional and whole gut transit time with wireless motility capsule. J Neurogastroenterol Motil. 2014;20(2):265–270. PubMed doi:10.5056/jnm.2014.20.2.265