Weight Category Sports
Chapter 49 Weight Category Sports JACK H. WILMORE Introduction Most athletes are concerned with either attaining or maintaining an optimal body weight and composition for their sport, or event within their sport. For some athletes, increased body size can be an advantage (e.g. basketball, rugby and American football), providing that the increase in size is the result of an increase in the athlete’s fat-free mass. For other athletes, body size is not nearly as important, but it is critical to maintain a low relative body fat (% fat mass) and a high relative fat-free mass (% fat-free mass) to optimize performance (e.g. distance running, soccer and swimming). For still other athletes, their body weight is dictated by a speciﬁc weight category (range of weights) within which the athlete must fall in order to be eligible to compete (i.e. weight category sports). Weight category sports include all sports in which the athlete must compete within a given weight category. Examples of weight category sports are provided in Table 49.1. There are also sports, or events within a sport, which are weight controlled. In these sports or events, competition is not organized by weight categories, yet the tradition of the sport or event dictates a slim ﬁgure, and thus a low body weight. For example, in diving and ﬁgure skating, athletes are rated by judges as to how well they perform a certain dive or skating routine. While the emphasis in judging is to be placed on the athlete’s performance, appearance does play a signiﬁcant role, and a leaner body is associated with success. Examples of weight-controlled sports are provided in Table 49.1. Weightcontrolled sports are included with weight category sports in this chapter as they share a number of common nutritional concerns. Weight-controlled sports are also addressed in Chapter 39. Weight category and weight-controlled sports and events present a unique challenge from the nutritional perspective (Wilmore 1992). Many of these athletes are consciously trying to either reduce weight or maintain a weight well below what would be considered normal or optimal for them. This leads to a variety of unhealthy nutritional practices, including skipping meals, avoiding speciﬁc foods or food groups which are necessary for meeting the minimum daily requirement for certain vitamins, minerals or macronutrients, and the binge–purge syndrome, including the use of diuretics and laxatives, among others. This chapter will focus on nutritional issues unique to weight category and weight-controlled sports. It will address techniques used to achieve weight loss and weight maintenance for these sports, the health, physiological and performance consequences of weight loss and maintenance through these techniques, and practical considerations as to how to best achieve and maintain an optimal body weight for these sports. 637 638 sport-specific nutrition Weight loss and weight maintenance techniques For both weight category sports and weightcontrolled sports, the rate of weight loss can be rapid (i.e. within 24–72 h), moderate (from 72 h to several weeks), or gradual (from several weeks to months). In some sports, moderate and rapid weight loss will occur many times over a single season. Tipton has stated that in wrestling, this process can be repeated between ﬁve and 30 times per season (Tipton 1981). Thus, the consequences of not only an acute period of moderate or rapid weight loss must be considered, but also the cumulative effects over the course of a season where there are multiple bouts of weight loss and Table 49.1 Examples of weight category and weightcontrolled sports and events. Weight category sports Weight-controlled sports Body building Boxing Horse racing (jockeys) Martial arts (e.g. judo, karate) Rowing Weight lifting Wrestling Dance (ballet) Distance running Diving Figure skating Gymnastics Synchronized swimming weight regain, or what has been termed weight cycling. The magnitude of the weight loss per cycle can also be substantial. Steen and Brownell (1990), in their survey of 63 college wrestlers and 368 high school wrestlers, reported that 41% of the college wrestlers reported weight losses of 5.0–9.1 kg each week of the season while 23% of the high school wrestlers lost 2.7–4.5 kg weekly. For sports like wrestling, where both rapid and moderate rates of weight loss are used, the techniques for achieving a given weight loss are quite varied. Horswill (1994) has listed a number of common methods of weight loss used by wrestlers which are presented in Table 49.2. The technique of negative energy balance is common across rapid, moderate and gradual rates of weight loss. Dehydration, purging and the other techniques listed in Table 49.2 are most common for rapid weight loss, but can extend across the moderate rate of weight loss category as well. Establishing a negative energy balance is the preferred technique for weight loss. However, this technique has limited efﬁcacy when the athlete must lose weight in a short period of time. Ideally, the athlete will establish a goal weight well in advance of his or her need to achieve that weight. A negative energy balance of 2100–4200 kJ (500–1000 kcal) daily is ideal, and this should be achieved through a balance of Table 49.2 Methods of weight loss used by wrestlers. Adapted from Horswill (1994). Method Negative energy balance Increase energy output Decrease energy intake Intentional dehydration Metabolic Thermal Diuresis Bloodletting Purging Other Example Weight loss compartment Body cell mass Aerobic training Diet, fasting Body water Exercise Sauna, sweat suit, rubber suit Diuretics, high-protein diet Laxatives, vomiting Haircut Inversion* Gastrointestinal tract Body cell mass * Inversion involves the wrestler standing on his head to redistribute his blood and body ﬂuids, which some wrestlers believe affects the scale reading. weight category sports 639 Fig. 49.1 Rapid weight loss to make weight for competition can pose health risks and can impair performance. However, as long as competitors perceive an advantage, the practice will persist. Photo © Allsport / D. Leah. increased energy expenditure and decreased energy intake. The objective is to reach the desired goal weight over a reasonable period of time, minimizing the potential loss of fat-free mass (Wilmore 1992). It has been clearly established that for both rapid and moderate rates of weight loss, a substantial percentage of the weight loss, i.e. 50% or more of the weight, can be derived from the fatfree mass, predominantly from the total body water and protein stores. In fact, with very low energy diets (i.e. 1680–3360 kJ · day–1, 400– 800 kcal · day–1) or low energy diets extended over longer periods of time, water and protein can still constitute a substantial percentage of the weight lost. Keys et al. (1950), in their classic series of studies on human starvation, fed nonobese adult men a test diet of 6570 kJ · day–1 (1570 kcal · day–1) for 24 weeks. The subjects’ diet which maintained stable weight prior to going on the low energy diet was 14.5 MJ · day–1 (3468 kcal · day–1). Over the ﬁrst 11 weeks, approximately 40% of the weight lost was from fat, 12% from protein, and 48% from water, with an average rate of weight loss of 0.15 kg per day. In a study of obese subjects, Yang and Van Itallie (1976) reported an average rate of weight loss of 0.45 kg per day in obese subjects on a 5020 kJ · day–1 (1200 kcal · day–1) mixed diet over the ﬁrst 5 days on the diet. Water comprised 66% of the total weight loss. The relatively high contribution of water to initial weight losses is at least partially the result of obligatory water loss accompanying the metabolism of glycogen and protein. Both glycogen and protein have hydration ratios of approximately 3–4 g water · g–1 of substrate, both for storage and degradation (Van Itallie & Yang 1977). Thus, athletes must be very careful when dieting to maximize weight loss while minimizing loss of fat-free tissue. Again, it is important to combine exercise with diet to achieve a given energy deﬁcit per day. Including exercise as a component of the energy deﬁcit attenuates the loss of fat-free mass when compared to diet alone (Ballor & Poehlman 1994; Saris 1995). Dehydration is the most widely used technique for rapid weight loss. Intentional dehydration is probably a better phrase to use since the intent of the technique is speciﬁc to producing body water loss, where unintentional dehydration is an unexpected consequence of negative energy balance resulting from the obligatory water loss associated with glycogen and protein degradation. With intentional dehydration, both metabolic and thermal techniques are intended to induce water loss through sweating, although an added bonus from exercise is the obligatory water loss from depletion of the body’s glycogen stores as discussed previously. Sweat losses, 640 sport-specific nutrition which are composed mostly of water, can be as high as 2–3 l · h–1 in men acclimatized to heat over the short term, and up to 10–15 l · day–1 (Wenger 1988). Sauna and sudation or water vapourbarrier garments have been widely used to promote sweating, and the subsequent loss of water can be considerable. These techniques are not without risk or negative consequences (Vuori & Wilmore 1994), but dehydration remains a powerful tool for major losses of weight in short periods of time. Dehydration can potentially be induced by the use of a high-protein diet, as water loss has been associated with a high-protein diet. However, the contribution of a high-protein diet to water loss is most likely associated with the fact that carbohydrate intake is reduced. This forces the body to rely more on fats, with the resulting production of ketone bodies. It has been clearly established that an excessive formation of ketone bodies, or ketosis, leads to diuresis. Also, as the intake of carbohydrate is limited, muscle and liver glycogen stores are gradually depleted, resulting in further water loss, i.e. the obligatory water loss associated with glycogen degradation. Prescription diuretics are also used to induce dehydration, although these are on the banned list of substances for use by athletes (Wadler & Hainline 1989). Certain foods, particularly alcohol and those foods containing caffeine, have substantial diuretic properties. However, caffeine is a banned substance when ingested in excessive quantities, e.g. 6–8 cups of coffee in one sitting (Wadler & Hainline 1989). Refer to Chapter 28 for further details. Bloodletting has been stated as a method used for weight loss by wrestlers (Horswill 1994); however, it is unclear if this is widely practised. This was not mentioned as a technique for weight loss in the comprehensive review of Fogelholm (1994), and was not included as a technique for weight loss in a large survey of high school wrestlers (Weissinger et al. 1991). Most likely, bloodletting is not widely used for weight loss in athletes, as most athletes do not like invasive techniques and recognize the obvious physiological and performance disadvantages of blood loss. Purging behaviours are discussed in detail in Chapter 39, and will not be addressed in detail in this chapter. Self-induced vomiting and the use of laxatives are the primary purging behaviours. These behaviours can lead to transient weight losses, but have substantial clinical risk, are potentially addictive, and can negatively impact athletic performance. While haircuts and inversion might be used in hopes of reducing the athlete’s weight, there is no evidence to support the efﬁcacy of these techniques. Health consequences of weight loss Athletes generally lose weight for one of three purposes: to qualify for a speciﬁc weight category, to achieve a more aesthetic appearance, and to improve performance potential. There are a number of questions raised concerning the potential for detrimental health consequences of weight loss. While most critical attention has been focused on rapid and moderate rates of weight loss, there is also concern over gradual, long-term weight loss. Each of these will be addressed. The primary concern with rapid and moderate rates of weight loss is the consequences of severe dehydration. Wrestlers have reduced body weight by 4–5% in 12–24 h, and losses of up to 12% of body weight have been reported (Brownell et al. 1987; Fogelholm 1994). The greatest percentage of the weight lost is from the total body water stores. Water accounts for approximately 60% of the total weight of an adult man. Thus, for a 70-kg man, total body water would represent about 42 kg, or 42 l, assuming a water density of 1.000. The intracellular ﬂuid accounts for about 67% of the total body water, or 28 l, and the extracellular ﬂuid accounts for the remaining 14 l. Of the 14 l of extracellular ﬂuid, plasma volume would account for 3 l and the interstitial ﬂuid would account for the remaining 11 l (Guyton & Hall 1996). With rapid weight loss, water is lost from each of the ﬂuid compart- weight category sports 4.0 11% 3.5 3.0 10% Total body water loss (l) ments. It has been estimated that the intracellular compartment can contribute 30–60% of the total; the interstitial ﬂuid, 30–60% of the total; and the plasma volume, 8–12% of the total (Mack & Nadel 1996). In a study by Costill et al. (1976), eight healthy . men cycled at 70% of Vo2max. in an environmental chamber (Tamb = 39°C) until they were progressively dehydrated by 2%, 4% and 6% of their initial body weight during a single, prolonged exercise bout. After achieving each level of dehydration, the subjects rested for 30 min in a supine position while a blood sample and muscle biopsy were obtained. Plasma and muscle water contents were reduced by 2.4% and 1.2%, respectively, for each percentage decrease in body weight. Figure 49.2 illustrates the changes in the plasma, interstitial and intracellular ﬂuid compartments at each level of dehydration. What are the health implications of such major changes in total body water? Of obvious concern is the potential for disturbances in thermoregulation. Sawka (1992) concludes from his review of the literature that hypohydration, consequent to dehydration, causes greater heat storage (i.e. increased core temperature) and reduces tolerance to heat strain. This is the result of reductions in the rate of sweating and skin blood ﬂow. Even with decreased skin blood ﬂow, there is still considerable displacement of blood to the skin for cooling, making it difﬁcult to maintain central venous pressure and an adequate cardiac output. Excessive sweat or urine loss could also result in large losses of electrolytes, which could possibly have serious health consequences, such as cardiac dysrhythmias. However, Costill (1977) has concluded that even those electrolyte losses can be large, they are largely derived from the extracellular compartment, and that losses of ions in sweat and urine have little effect on the K+ content of plasma or muscle. Further, concern has been expressed as to the effects of chronic dehydration on renal function. Zambraski (1990), in a review of renal function, ﬂuid homeostasis and exercise, concluded that exercise, particularly in conjunction with hypo- 641 39% 2.5 2.0 38% 1.5 10% 1.0 50% 60% 52% 0.5 30% 0 –2.2 –4.1 –5.8 Levels of dehydration (%) Fig. 49.2 Changes in the plasma (䊐), interstitial ( ) and intracellular water ( ) compartments with exercise and thermal dehydration of 2%, 4% and 6% of body weight. Adapted from Costill et al. (1976), with permission. hydration, sodium deprivation, and/or heat stress, presents a major stress to the kidneys. Renal vasoconstriction and antinatriuretic responses are increased in magnitude when dehydration and/or heat stress are combined with exercise. Exercise proteinuria and haematuria have been reported, indicating dramatic changes in renal function. However, the incidence of acute renal failure is relatively small. The long-term consequences of repeated episodes of acute renal stress are unknown. Repeated bouts of weight cycling have also 642 sport-specific nutrition been postulated to have negative health consequences (Brownell et al. 1987). These would include an increased energy efﬁciency, thus an increased risk of weight gain, increased deposition of fat in the upper body (i.e. visceral fat), lipid and lipoprotein disorders, reproductive disorders such as delayed menarche and secondary amenorrhoea, and bone mineral disturbances consequent to secondary amenorrhoea. Fortunately, most of these concerns have now been clearly established to be unrelated to weight cycling (van der Kooy et al. 1993; Anonymous 1994; Jeffery 1996). Athletes attempting to maintain a body weight which is lower than that which is normal and healthy for them is also a cause for concern. These athletes are often in a state of chronic energy deﬁcit (i.e. energy expenditure > energy intake for many days, weeks or months). In female athletes, Loucks and Heath (1994a, 1994b) have demonstrated that once the energy deﬁcit exceeds a certain critical level, reproductive and thyroid function are suppressed, which might serve as a trigger for athletic amenorrhoea (secondary amenorrhoea in the athletic population). Amenorrhoea in athletes is associated with low concentrations of 17b-oestradiol and progesterone, which are, in turn, associated with low bone mineral density in the spine (Snead et al. 1992). The combination of disordered eating (including energy deﬁcit), amenorrhoea and bone mineral disorders has been termed the ‘female athlete triad,’ with the assumption that disordered eating can lead to menstrual dysfunction, which, in turn, can lead to bone mineral disorders (Wilmore 1991). The female athlete triad has become a topic of great concern and is the focus of a recent position statement by the American College of Sports Medicine (Otis et al. 1997). Physiological and performance consequences of weight loss With rapid and moderate rates of weight loss, there will be reductions in total body water, muscle and liver glycogen stores, as well as in other components of the fat-free mass (Oppliger et al. 1996). For the most part, these athletes are already very lean prior to weight loss, and so very little of the weight lost will be derived from the fat stores. In fact, Friedl et al. (1994) have reported that there is likely a lower limit to the loss of body fat with weight loss in lean individuals. In a group of 55 soldiers participating in an 8-week Ranger Training Course, those who achieved a minimum relative body fat of 4–6% by 6 weeks demonstrated only small additional total and subcutaneous fat losses in the ﬁnal 2 weeks and lost increasingly larger proportions of fat-free mass. Therefore, as the athlete reaches a low total fat mass, there is a reduced likelihood of further losses of body fat with weight loss. Consequently, the percentage of the actual weight loss from the fat-free mass during rapid and moderate rates of weight loss is likely to be high. Generally, decrements in performance are associated with losses in the body’s fat-free mass (Wilmore 1992). Several recent papers have reviewed the research literature on the effects of rapid and moderate rates of weight loss on physiological function and performance (Fogelholm 1994; Horswill 1994; Oppliger et al. 1996). The results of these reviews are summarized in Table 49.3. Since there is typically an interval of time between weigh-in and actual competition for most sports, ranging from a few minutes up to 20 h or more, it is extremely important to understand how physiological function and performance respond following a variable period of rehydration and replenishment of nutrients. Unfortunately, while a great deal is known about the effects of acute dehydration on physiological function and performance, far less is known about the regain in function and performance with rehydration and intake of nutrients. From this table, it is very clear that rapid or moderate rates of weight loss can have major effects on both physiological function and performance. What is less certain are the potential changes that occur with rehydration and food intake during the interval of time between weigh-in and competition. It appears that some weight category sports 643 Table 49.3 Alterations in physiological function and performance consequent to rapid and moderate rates of dehydration. Data from reviews of Fogelholm (1994), Horswill (1994), Keller et al. (1994) and Oppliger et al. (1996). Variables Physiological function Cardiovascular Blood volume/plasma volume Cardiac output Stroke volume Heart rate Metabolic . Aerobic capacity (V o2max.) Anaerobic power (Wingate test) Anaerobic capacity (Wingate test) Blood lactate (peak value) Buffer capacity of the blood Lactate threshold (velocity) Muscle and liver glycogen Blood glucose during exercise Protein degradation with exercise Thermoregulation and ﬂuid balance Electrolytes (muscle and blood) Exercise core temperature Sweat rate Skin blood ﬂow Performance Muscular strength Muscular endurance Muscular power Speed of movement Run time to exhaustion Total work performed Wrestling simulation tests† Dehydration Rehydration Ø Ø Ø ≠ Ø* ? ? ? ´, Ø ´, Ø ´, Ø Ø Ø Ø Ø Possible Ø Possible ≠ ´* ´, Ø ´, Ø Ø* ? ? Ø ? ? Ø ≠ Ø, delayed onset Ø ´ ? ? ? ´, Ø ´, Ø ? ? Ø Ø Ø ´, Ø ´, Ø Ø† ? ? Ø* ´ Ø† Ø, decrease; ≠, increase; ´, no known change, or return to normal values; ?, unknown. * From Burge et al. (1993). † From Oopik et al. (1996). of the function and performance that was lost during an acute episode of a rapid or a moderate rate of weight loss can be regained within 5–20 h providing ample food and beverage are available and the athlete is willing to eat. There are still many questions to be answered regarding the total efﬁcacy of eating and drinking during this period between weigh-in and competition with respect to regaining normal physiological function and performance. The issue of replacing carbohydrate postexercise is covered in Chapter 7, and rehydration after exercise-induced sweat loss is covered in Chapter 19. Practical considerations for weight loss As stated in a previous section of this paper, the ideal way to lose weight for competition is to establish a goal weight several months in advance of the start of the competitive season, and achieve this goal weight by gradual reductions in body fat of not more than 0.45–0.9 kg · week–1 while maintaining or increasing the fatfree mass. Koutedakis et al. (1994) have shown that weight reduction of the same magnitude (6–7% of body weight) over 2 months vs. 4 644 sport-specific nutrition months in the same athletes 1 year later adversely altered ﬁtness-related performance parameters in international lightweight oarswomen. Unfortunately, for many athletes a prolonged weight loss protocol is not possible. Since most of them are already very lean (low fat mass), they are able to achieve their competitive weight only by losing large amounts of fat-free weight with minimal losses of fat mass. This is accomplished primarily through decreases in the total body water stores, and the muscle and liver glycogen stores, both of which are critical to successful performance. Therefore, the length of time between the weigh-in and competition is extremely important, as is the ﬂuid and nutrient replenishment protocol. While a solid data base is not yet available, it would seem logical that the longer the period of repletion of ﬂuid and energy stores, and the more ﬂuid and energy the athlete can ingest during this period, the better will be the subsequent performance. What might be an optimal rehydration/ refeeding protocol? Of primary concern would be the need to replenish both ﬂuid and glycogen stores. Of secondary concern would be the replacement of electrolytes lost during the process of dehydration. However, electrolyte replacement is essential for the restoration of ﬂuid balance (Maughan & Leiper 1995; Shirreffs et al. 1996). Thus, it would seem logical to use both a sports drink (5–10% carbohydrate and electrolytes) plus a high-carbohydrate food source such as sports bars (providing there is at least 2–3 h before competition). The combination of the sports drink and sports bar should provide optimal replenishment for the time available. Since there is not a good data base on this issue, athletes should be encouraged to experiment with different combinations to see what works best for them, keeping in mind that they need to replenish both ﬂuids and glycogen. Effective strategies to make weight would include each of the following. • Compete in an attainable weight category — do not drop down to an unrealistic category. • Lose most of the weight preseason, and lose it gradually to maximize fat loss. • Ideally, if you need to lose 10% of body weight, lose the ﬁrst 6% gradually during the preseason, and the last 4% through dehydration 24–48 h prior to competition. • Eat a high-carbohydrate diet during training and during periods of weight loss to maintain as best as possible muscle and liver glycogen stores. • Supplement vitamins and minerals if restricting food to lose weight. • Maintain normal hydration during training, except for the 24–48-h period before weigh-in if it becomes necessary to dehydrate to make weight. • Maximize the period of time between weigh-in and competition to replenish both water and energy stores. References Anonymous (1994) Weight cycling: National Task Force on the Prevention and Treatment of Obesity. 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