Nutrition for Power Sports: Middle-Distance Running, Track Cycling, Rowing, Canoeing/Kayaking, and Swimming

Journal of Sports Sciences, 2011; 1–11, iFirst article

Nutrition for power sports: Middle-distance running, track cycling, rowing, canoeing/kayaking, and swimming

TRENT STELLINGWERFF1, RONALD J. MAUGHAN2, & LOUISE M. BURKE3

1Nestle´ Research Centre, Lausanne, Switzerland, 2School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK, and 3Department of Sports Nutrition, Australian Institute of Sport, Belconnen, ACT, Australia

(Accepted 16 May 2011)

Abstract Contemporary training for power sports involves diverse routines that place a wide array of physiological demands on the athlete. This requires a multi-faceted nutritional strategy to support both general training needs – tailored to specific training phases – as well as the acute demands of competition. Elite power sport athletes have high training intensities and volumes for most of the training season, so energy intake must be sufficient to support recovery and adaptation. Low pre-exercise muscle glycogen reduces high-intensity performance, so daily carbohydrate intake must be emphasized throughout training and competition phases. There is strong evidence to suggest that the timing, type, and amount of protein intake influence post-exercise recovery and adaptation. Most power sports feature demanding competition schedules, which require aggressive nutritional recovery strategies to optimize muscle glycogen resynthesis. Various power sports have different optimum body compositions and body weight requirements, but increasing the power-to-weight ratio during the championship season can lead to significant performance benefits for most athletes. Both intra- and extracellular buffering agents may enhance performance, but more research is needed to examine the potential long-term impact of buffering agents on training adaptation. Interactions between training, desired physiological adaptations, competition, and nutrition require an individual approach and should be continuously adjusted and adapted.

Keywords: Power sports, periodized nutrition, recovery, adaptation, body composition, supplements, performance

result in nutritional challenges that can be best Introduction addressed through a periodized nutritional approach. While some sports emphasize the exclusive develop- Only a few previous reviews have focused on the ment of strength or endurance, several sports require complexities of power sport athletes (Maughan et al., high power output for success. Power is the rate at 1997; Stellingwerff, Boit, & Res, 2007a). The focus which work is performed or energy is produced. of the current article is to outline nutrition recom- Most elite power sport athletes can sustain very high mendations during training and competition, speciﬁc power outputs (20 kcal min71; 500 W) at greater to power-based athletes involved in events of 1– _ than 100% of maximal oxygen uptake (V O2max), 10 min duration, including middle-distance run- over races lasting up to 10 min (Table I), which ning, track cycling, rowing, canoeing/kayaking, and Downloaded by [University of California Santa Cruz] at 16:21 14 October 2011 result in post-exercise blood lactate concentrations in swimming. In this review, we provide practical excess of 20 mmol L71. Accordingly, these athletes nutrition recommendations based on modern scien- utilize the continuum of energy systems to supply tiﬁc data for acute and chronic training and adenosine triphosphate (ATP) to meet their energy competitive situations. We also highlight body demands, and are completely reliant upon endogen- composition considerations and supplements that ously stored fuel. To fully develop all energy systems, are relevant to power athletes. elite power athletes undertake a modern periodized training approach that features a high volume of training during aerobic development and high- Fuel utilization and energy systems in intensity training during the competition phase, power sports coupled with strength training. The demanding competition schedules of power athletes and the A brief overview of energy systems and fuel complexities of micro- and macro-training cycles utilization will set the structure for subsequent

Correspondence: T. Stellingwerff, Nestle´ Research Centre, PO Box 44, CH-1000 Lausanne, Switzerland. E-mail: [email protected] ISSN 0264-0414 print/ISSN 1466-447X online Ó 2011 Taylor & Francis DOI: 10.1080/02640414.2011.589469 2 T. Stellingwerff et al.

Table I. Differences in energy source provision in power-based sporting events.

% Energy contribution Approx. % _ Event time range Event example VO2max Phospho Glycolysis Oxidative

0.5 to 1 min 400-m running; individual cycling time-trial *150 *10 *47–60 *30–43 (500 m or 1 km); 100-m swimming disciplines 1.5 to 2 min 800-m running; 200-m swimming disciplines; 113–130 *5 *29–45 *50–66 500-m canoe/kayak disciplines 3 to 5 min 1500-m running; cycling pursuit; 400-m swimming 103–115 *2 *14–28 *70–84 disciplines; 1000-m canoe/kayak disciplines 5 to 8 min 3000-m running; 2000-m rowing 98–102 51 *10–12 *88–90

Note: Phospho ¼ phosphagen breakdown; Glycolysis ¼ non-oxidative glycolysis (anaerobic metabolism); Oxidative ¼ oxidative phosphorylation (aerobic metabolism). Data adapted from Spencer and Gastin (2001).

nutritional recommendations. Table I outlines the Nutrition for training approximate fractional energy contribution across a Periodized nutrition for the yearly training programme range of event lengths for the three energy systems that provide ATP, namely: (1) phosphagen break- Although the concept of training periodization has down, (2) non-oxidative glycolysis (‘‘anaerobic’’ been around since the 1950s, the concept of coupling glycolysis), and (3) oxidative phosphorylation training with nutrition and body composition period- (‘‘aerobic’’ metabolism). Carbohydrate provides ization is just starting to gain scientific awareness the majority of the fuel for exercise intensities above (Stellingwerff et al., 2007a). Periodization is defined _ 75% V O2max, and is a fuel for both non-oxidative as the purposeful sequencing of different training glycolysis and oxidative phosphorylation. In con- units (macro- and micro-training cycles and ses- trast, fat is metabolized exclusively via oxidative sions), so that athletes can attain the desired phosphorylation. Oxidative phosphorylation pro- physiological readiness for optimum on-demand vides the bulk of ATP provision during low-intensity performances (Bompa & Carrera, 2005). Traditional exercise, primarily utilizing Type I muscle fibres. periodization sequences training into the four main However, during exercise of increasing intensity, macro-cycles of ‘‘general preparation phase’’, ‘‘spe- when ATP production from oxidative phosphoryla- cific preparation phase’’, ‘‘competition phase’’, and tion cannot match the rate of ATP hydrolysis, the ‘‘transition phase’’. However, the training stimuli shortfall in ATP supply is met by substrate level during these different phases can differ drastically in phosphorylation. This system provides energy via terms of intensity and volume. Therefore, the types phosphagen utilization and the metabolism of of fuels and the amount of energy that are used to muscle glycogen and plasma glucose, via the generate the required ATP during these phases need glycolytic pathway, with lactate formation. During to be addressed through a periodized nutritional moments of high energy demand, there is an approach (Table 1; Figure 1). General macronu- increased activation of Type IIa muscle fibres, trient and energy intake recommendations for Downloaded by [University of California Santa Cruz] at 16:21 14 October 2011 which have both a high oxidative and glycolytic athletes when training and in competition are capacity. At very high workloads, Type IIb muscle covered by Burke and colleagues (Burke, Hawley, fibres become activated to maintain the high Wong, & Jeukendrup, 2011), Loucks and co-workers demand for ATP provision via glycolysis and (Loucks, Kiens, & Wright, 2011), and Phillips and phosphagen breakdown, leading to the extreme Van Loon (2011), but further recommendations levels of lactate production associated with many specific to power athletes will be made in this review. power sport events. Therefore, power athletes have several highly developed energy-producing pathways General macronutrient and energy intake recommenda- that utilize different blends of phosphagen, carbohy- tions. During most of the training season, adequate drate, and/or fat, coupled with greater muscle energy must be consumed to support the training buffering capacity, to handle a range of different volume and intensity. For example, the training load metabolic demands during varying exercise inten- of elite swimmers can involve individual swim sities. This understanding of the different energy practices lasting more than 3 h with over 10,000 m systems and the fuels required to produce ATP covered, and daily energy needs are calculated to be must be taken into consideration when making about 3000–6800 kcal day71 for males and about nutrition recommendations. 1500–3300 kcal day71 for females (Van Handel, Nutrition for power sports 3

Figure 1. Overview of general nutrition recommendations during different yearly training phases for power athletes. Nutrition recommendations for a 70–kg power sport athlete. Prep, preparation; CHO, carbohydrate; FAT, fat; PRO, protein; kcal, nutritional calorie. Adapted from Burke et al. (2001), Tarnopolsky (1999), and Tipton and Wolfe (2004).

Cells, Bradley, & Troup, 1984). Many power athletes natural, and due to the diminished or non-existent undertake 9–14 training sessions each week, with training, energy intake during this phase/day should workouts from about 30 min to 3 h in duration, be reduced towards nutritional recommendations including resistance and plyometric/neuromuscular that are similar to those of the general public training several times per week. Dietary intake studies (Figure 1). typically ﬁnd that female athletes report substantially lower energy intake per kilogram of body weight Dietary carbohydrate intake recommendations.The Downloaded by [University of California Santa Cruz] at 16:21 14 October 2011 (BW) than male athletes: *40 kcal kg BW71 seminal paper by Bergstrom and colleagues (Berg- day71 for females versus *55 kcal kg BW71 day71 strom, Hermansen, Hultman, & Saltin, 1967) showed for males (Burke, Cox, Cummings, & Desbrow, that a high carbohydrate diet led to augmented 2001). Lower daily energy and carbohydrate intake in glycogen stores, translating into a longer time to females may be due to greater under-reporting on exhaustion than after a low carbohydrate diet. Con- dietary surveys, lower energy/carbohydrate require- versely, extremely low carbohydrate diets (3–15% ments due to lower training volumes and intensities carbohydrate) have uniformly been shown to impair than their male counterparts, or a combination of both high-intensity and endurance-based perfor- these factors. mance (Coggan & Coyle, 1991; Maughan & Poole, Many athletes aspire to be at competition target 1981). The amount of carbohydrate that is oxidized body weight or body composition year round, which during exercise depends on both exercise intensity is physiologically and psychologically challenging. and duration, with carbohydrate oxidation providing During the transition phase, most athletes take a the majority of ATP when exercising above 75% _ period of rest for both mental and physical recovery V O2peak. Owing to high exercise intensities during in which training volume and intensity are generally the speciﬁc preparation and competition phases, the very low. Some weight gain during this phase is relative dependency on carbohydrate-based ATP 4 T. Stellingwerff et al.

provision increases throughout yearly training macro- the protein to increase protein synthesis and optimize cyles. However, given the large training volumes post-exercise recovery. during the general preparation phase, the absolute requirement for carbohydrate is high, thus carbohy- Dietary fat intake recommendations. Although the drate-rich foods must provide the majority of majority of dietary fuel for power sport athletes is the energy provision throughout the training year in the form of carbohydrate, fat also serves many (Figure 1). important roles and is a vital fuel source during An examination of dietary studies of power-based endurance training. Skeletal muscle can store nearly sports, albeit usually of sub-elite populations, shows the energy equivalent of glycogen in the form of that male athletes typically report daily carbohydrate intramuscular triacylglyceride, which is a viable fuel intakes averaging approximately 8–9 g kg BW71 source during prolonged moderate-intensity exercise 71 _ day , which is within the recommended range, up to about 85% V O2max (Stellingwerff et al., while the apparent intake of females is considerably 2007b). The general preparation phase features lower at *5.5 g kg BW71 day71 (Burke et al., considerable amounts of endurance training where 2001). It is absolutely clear that low pre-exercise endogenous fats are a significant source of fuel muscle glycogen concentrations result in reduced (Figure 1). The amount of dietary fat required for high-intensity performance over a cycling test lasting daily intramuscular triacylglyceride repletion after about 5 min (Maughan & Poole, 1981), and that prolonged (42 h) endurance training has been constantly training in an energy and carbohydrate estimated at 2 g kg BW71 day71 (Decombaz, depleted state may compromise immune function, 2003), while fat intakes greater than this may training staleness, and burnout. Therefore, depend- compromise muscle glycogen recovery and muscle ing on individual training volume and intensity, a tissue repair by displacing the intake of adequate habitually high carbohydrate diet of about 6–12 g amounts of dietary carbohydrate and protein. At kg BW71 day71, with females on the lower end certain times of the year, such as the competition and males on the higher end of the range, is phase, fat intake may be limited to reduce total recommended to maintain immune function, re- energy intake to achieve body composition optimiza- cover glycogen storage, and reduce over-reaching tion. However, throughout all training phases, some (Figure 1). Several studies have shown the potential dietary fat is always needed to aid absorption of fat- beneficial effects of training with low/restricted soluble vitamins and to provide substrate for carbohydrate availability during specific training hormone synthesis, as well as for cellular membrane sessions (reviewed by Burke et al., 2011). However, and myelin sheath integrity. this approach remains controversial in terms of performance outcomes, and appears more applicable Fuelling and fluids during training to endurance athletes than power athletes. Since power sport events last only a few minutes, Dietary protein intake recommendations. Few studies there is no opportunity for fuelling (carbohydrate) have examined the protein needs of power sport and fluid intake during competition. However, given athletes, as most recommendations have been made that some training sessions during the general for either pure strength- or endurance-trained ath- preparation phase can approach 2 h in length, there letes. However, the daily protein requirement is is ample opportunity to benefit from carbohydrate probably based on the quantity and quality of training and fluid intake during training. Current recommen- Downloaded by [University of California Santa Cruz] at 16:21 14 October 2011 rather than the specific sport discipline. During stable dations for carbohydrate are set to 30–60 g h71 for training periods, protein intake greater than 1.7 g kg athletes during exercise, with greater amounts for BW71 day71 has been shown to lead to increased exercise exceeding 2 h. For an overview of current protein oxidation. Therefore, it is suggested that elite recommendations on carbohydrate and fluid intake athletes who undertake a large and intense training during training, see Burke et al. (2011), Jeukendrup load will meet their protein requirements with an (2011), and Shirreffs (2011). intake of 1.5–1.7 g kg BW71 day71 (Figure 1; Some power sports feature highly technical com- Tarnopolsky, 1999). Dietary surveys of westernized ponents (e.g. swim stroke technique). Consequently, athletes have consistently shown that athletes who carbohydrate intake during training can not only consume more than 3000 kcal day71 most likely assist in providing energy, but also neuromuscular consume protein at or above these levels. However, support via the attenuation of cognitive fatigue, beyond satisfying the current daily protein intake which can reduce technical errors and enhance skill recommendations, emerging evidence strongly sug- development, as previously demonstrated in team gests that the timing, type, and amount of protein sport models (Currell, Conway, & Jeukendrup, consumed over the day, and in relation to exercise 2009). The high intensity of power sport training sessions, will have a marked effect on the efficacy of sometimes prevents the ingestion of carbohydrate Nutrition for power sports 5

and fluids during training due to associated gastro- with carbohydrate, caused a glycogen super- intestinal problems. However, several recent papers compensation effect within 24 h (Roberts et al., have shown that carbohydrate mouth-washing alone 2004). However, creatine intake in combination with (for about 12 s every 7–10 min), without carbohy- carbohydrate did not affect the very short-term drate consumption, improved one-hour time-trial (56 h) glycogen resynthesis rate (Robinson et al., performance (Carter, Jeukendrup, & Jones, 2004), 1999). Van Loon et al. (2004) also demonstrated that with the mechanism involving the activation of high-dose creatine (20 g day71) over 6 days reward-related brain regions (Chambers, Bridge, & augmented muscle glycogen stores, but this effect Jones, 2009). Anecdotal reports have demonstrated was not maintained over a further 37 days successful utilization of carbohydrate mouth-washing when participants were placed on low-dose creatine during rests within high-intensity interval training (2 g day71). However, this low-dose creatine sessions as a way to stimulate the quality and protocol did not maintain augmented total creatine performance of the training, while circumventing stores compared with the 6-day creatine loading any negative gastrointestinal side-effects associated phase. Taken together, it appears that a high creatine with fluid intakes during this type of session loading dose is needed to augment glycogen stores (unpublished observations). However, whether car- concomitantly with creatine stores, and this effect bohydrate mouth-washing improves high-intensity may be seen already by 24 h after supplementation. repeated sprint interval performance remains to be However, given that high-dose creatine intake may confirmed in a well-controlled study. cause a 2–3% increase in body weight, the potential benefits of *20% higher muscle glycogen need to be weighed against the potential negative performance Nutrition strategies to optimize recovery effects of body weight gain on an individual and Given the diversity of training and competition that sport-specific basis. power athletes undertake, an individualised post- training nutritional recovery approach needs to be Protein synthesis. The details of the role that specific implemented. Table II illustrates the different train- proteins and their timing play in enhancing post- ing and competition situations that will dictate exercise muscle protein synthesis is covered else- different specific recovery needs and, consequently, where in this issue (Phillips & Van Loon, 2011). different nutritional recommendations. The primary Although it has yet to be clearly established whether focus for power athletes is the recovery of muscle more or less protein is needed to optimize acute energy stores (primarily glycogen) and the synthesis protein synthesis for athletes of varying muscle of new proteins. Although fat consumption plays a mass, given the huge diversity in body weights fundamentally important role in the general diet, it among power athletes, a body weight-corrected remains to be shown whether increased fat intake dose of *0.3 g protein kg BW71 might be a during recovery results in a beneficial recovery prudent way to describe the optimum post-exercise profile. protein dose (Table II). However, more studies are needed to examine nutritional timing of protein Glycogen resynthesis. Since muscle glycogen is the throughout the day, and in particular around primary fuel for power athletes, and clear evidence exercise, to better elucidate the optimum timing suggests that low pre-exercise muscle glycogen for recovery and adaptation. Nevertheless, it can concentrations result in reduced high-intensity per- currently be concluded that protein and carbohy- Downloaded by [University of California Santa Cruz] at 16:21 14 October 2011 formance (Maughan & Poole, 1981), glycogen drate should be ingested in close temporal proxi- resynthesis after training or competition is of utmost mity to the exercise bout to maximize the anabolic importance. In short, 1.2–1.5 g carbohydrate kg response to training. BW71 ingested soon after exercise will optimize muscle glycogen re-synthesis, and when carbohydrate Nutrition for competition is consumed at this level the effect of added protein will be negligible, as further covered by Burke et al. Many power sports feature challenging competition (2011). However, specific to power sport athletes, schedules that require specific and timely nutrition several studies have shown an approximately 20% recommendations. For example, when exceptional higher muscle glycogen concentration concomitant swimmer Michael Phelps won eight gold medals at with increased total muscle creatine stores after the 2008 Beijing Olympics, he raced 20 times over creatine supplementation (20 g day71 for 5 days) nine consecutive days, and five of those days featured in combination with exercise (Robinson, Sewell, three races each. Even when power sport athletes Hultman, & Greenhaff, 1999; Van Loon et al., compete in a single event, major competitions 2004). Furthermore, a recent report has shown that typically schedule heats or rounds to qualify for the high-dose creatine (20 g day71), in combination final; recovery after each race will be the key to the Downloaded by [University of California Santa Cruz] at 16:21 14 October 2011 6 .Selnwrfe al. et Stellingwerff T.

Table II. Recommendations for recovery nutrition across different training and competition situations for power-athletes.

Speciﬁc type of training/race situation Intense short duration or prolonged Technical drills/short duration Situations of short recovery Long aerobic/endurance training resistance circuit training resistance training (54h)

Exercise characteristics . Prolonged aerobic exercise . High-intensity training of shorter . Low volume of explosive move- . Multiple races or training ses- (41 h) of easier intensity durations (*20–40 min) ments sions on the same day . Primarily oxidative metabolism . Primarily non-oxidative glycolytic . Primarily glycolytic and phos- (FAT and CHO) metabolism (primarily CHO) phagen metabolism (PCr þ CHO)

Training objective . Enhance oxidative enzymes, fat . Enhance glycolytic enzymes, buf- . Sub-maximal and maximal . N/A – speciﬁc to the training and metabolism and endurance fering capacity & lactate tolerance muscular strength, technique racing demands & muscular power and economy development . Energy replacement (FAT and . Energy replacement (primarily . Energy needs are low . Some energy replacement (pri- CHO) CHO) marily CHO)

Speciﬁc recovery needs . Carbohydrate intake of primary . Carbohydrate intake of primary . Lower carbohydrate intake needs . Carbohydrate intake of primary importance for glycogen re- importance for glycogen resynth- (some glycogen resynthesis importance for glycogen resynthesis esis needed) synthesis . Protein needed for muscle re- . Protein needed for muscle recov- . Protein needed for muscle re- . Focus on foods that are GI covery and re-modelling ery and re-modelling covery and re-modelling tolerable for subsequent exercise (minimize FAT and PRO intakes)

Macronutrient recom- . CHO: *1.2–1.5 g kg BW71 . CHO: *1.2–1.5 g kg BW71 . CHO: *0.5–1.0 g kg BW71 . CHO: *1.2–1.5 g kg BW71 mendations (within ﬁrst *2h) . PRO: *0.3 g kg BW71 . PRO: *0.3 g kg BW71 . PRO: *0.3 g kg BW71 . PRO: minimal requirements . FAT: *0.2–0.3 g kg BW71 . FAT: minimal requirements . FAT: minimal requirements . FAT: minimal requirements

Practical example for . 750 mL carbohydrate sports . Individual mini-veggie and meat . Fruit smoothie (*300 ml: . 750 mL carbohydrate sports 70-kg athlete drink, with protein recovery bar, pizza, *300 ml juice, and 1 piece skimmed milk, yogurt, fruit þ - drink and/or high carbohydrate and *300 ml milk of fruit protein powder) and 1 piece of food snacks (e.g. sports bar, fruit crackers, cookies, etc.)

Note: Nutrition recommendations adapted from Burke et al. (2001), Moore et al. (2009), Tarnopolsky (1999), and Tipton and Wolfe (2004). BW ¼ body weight; CHO ¼ carbohydrate; GI ¼ gastrointestinal; PCr ¼ phosphagen; PRO ¼ protein. Nutrition for power sports 7

ultimate outcome. In combination with the recovery and protein needs until a normal meal can be recommendations above, some competition-based consumed. practical suggestions are highlighted in Table II and below: Body composition considerations for power sport athletes . Before a championship, evaluate several individualized pre-competition meal options that are Although other articles in this issue (Loucks et al., convenient, readily available, and feel ‘‘right’’ for 2011; Sundgot-Borgen & Garthe, 2011) review the the athlete (no gastrointestinal discomfort). topic of altered energy balance in athletes, some These meals should be high in carbohydrate specific considerations for power athletes will be (1–4 g kg BW71), lower in protein and fat, and addressed here. For many athletes, achieving very consumed 1–6 h before competition (Burke low body fat and an increased power-to-weight ratio et al., 2011). can lead to significant performance increases. . Meals at dining-hall buffets can feature a large Furthermore, different power sports will dictate variety of food choice, but for some this can different optimum body composition and body mass cause over-eating. Athletes should select serving requirements. For example, despite the fact that sizes and food choices that are appropriate to 2000-m rowers (less weight-dependent) and 1500-m their needs (including considerations of re- runners (fully weight-dependent) both compete with duced energy expenditure during tapering a similar sustained power over about 3.5–6.0 min, phases) rather than being influenced by the the types of body composition that dictate success eating practices of other athletes or the foods are fundamentally different between these sports. available. Recording body weight daily can help Rowers are taller, stronger, and heavier than middle- athletes make sure they are on track. distance runners and have a lower relative aerobic _ . Due to the short race lengths, hydration is capacity (although absolute values of V O2max are normally not an issue for power athletes except higher in heavyweight rowers). There is a wide range when faced with multiple races per day. Athletes of normative data in elite power-based athletes, with should aim for 400–600 ml of a sport drink and/ body fat values of 5–10% for males and 8–15% for or water with electrolytes in the 1–2 h before females, and swimmers generally having 4–8% high- competition, unless they are sure that they are er body fat than endurance-matched runners (Fleck, well hydrated (Shirreffs, 2011). 1983). . Many athletes consume small carbohydrate- Achieving extremely low body fat is less important based snacks and sports drinks 1–3 h before a in weight-supported power sports, such as rowing or competition warm-up. When travelling, athletes track cycling, where high absolute power outputs are should try to pack some convenient and more important for performance, than in more favourite non-perishable snacks from home, weight-dependent power sports, such as middle- taking into consideration any customs require- distance running. Like training, body composition ments regarding the transport of food. should also be periodized throughout the year. . It is vital to plan ahead to ensure that suitable Although much research needs to be done to further post-competition foods and fluids are immedi- examine what optimum yearly fluctuations in body ately available to optimize post-competition weight and body fat might be, the practical experi- recovery. Carbohydrate-rich foods and fluids ence of the authors has shown that changes of around Downloaded by [University of California Santa Cruz] at 16:21 14 October 2011 with a medium to high glycaemic index at 1.0– 3–5% of body weight or percent body fat throughout 1.5 g carbohydrate kg BW71 for the first 4 h the year appear to be ideal. This allows athletes to be should be the target (Burke et al., 2011). at a slightly higher and healthier body weight and Practical considerations may include food body fat percentage for the majority of the training choices that can be suitably stored or prepared, year, while still being close enough to more easily or consumed in challenging circumstances and achieve target body composition for the peak in spite of reduced appetite. The busy competi- competition phase. Athletes should be at competition schedules of many athletes must often tion performance body weight and body composition accommodate warm-downs, drug testing, med- for only short periods of time, as aspiring to be in ia appearances, and other activities that can peak body composition year round by chronically interfere with the opportunity to eat. restricting energy availability results in an increased . Due to the usual competition venue and travel risk of injury and sickness, as well as a myriad of constraints, it is often difficult to get a normal other associated negative health and performance meal immediately after competition. Sports effects. nutrition products can provide convenience Very few scientific data have been published on and meet many of these initial carbohydrate elite athletes and body composition, as most previous 8 T. Stellingwerff et al.

studies involving negative energy balance have been longed supplementation of b-alanine to increase conducted in untrained individuals. However, recent muscle carnosine content to enhance intracellular data in trained individuals suggest that through buffering, and (2) the acute supplementation of aggressive exercise and dietary protein periodization, sodium citrate or bicarbonate to enhance extracel- muscle mass can be maintained while losing body lular buffering. As of 2010, these substances are not weight during a one-week period featuring a 40% on the World Anti-Doping Agency’s prohibited negative energy balance (Mettler, Mitchell, & Tip- substances list, and for further general information ton, 2010). In this study, participants utilized a on the risk and rewards of dietary supplements, see higher daily protein diet (*2.3 g kg BW71 day71) the review by Maughan and colleagues (Maughan, with resistance exercise to lose significant weight Greenhaff, & Hespel, 2011). (*1.5 kg), of which nearly 100% was fat loss rather than muscle loss. Therefore, a combined approach of Intracellular buffering: Carnosine slightly decreasing energy intake (*500 kcal), while either maintaining or slightly increasing energy Carnosine (b-alanyl-L-histidine) is a cytoplasmic expenditure, is the best approach to optimizing body dipeptide found at high concentrations in skeletal composition over an approximately 3–6 week period muscle and in particular Type II fibres (Artioli, prior to the targeted competitive season (Figure 1; Gualano, Smith, Stout, & Lancha, 2010; Derave, O’Connor, Olds, & Maughan, 2007). Therefore, Everaert, Beeckman, & Baguet, 2010). Higher con- during periods of negative energy balance in elite centrations have been found in sprinters and rowers athletes aspiring to lose weight, it has been proposed than in marathon runners (Parkhouse & McKenzie, to raise the daily protein intake to *35% of daily 1984). Carnosine is a potent intramuscular buffer needs, or about 1.5–2.5 g kg BW71 day71, which due to its nitrogen-containing imidazole ring, which appears to assist in lean tissue preservation (Phillips, can buffer Hþ ions with a pKa of 6.83, thus slowing 2006). Ultimately, an individualized approach needs the decline in pH during intense exercise. Supporting to be taken and extremely low body fat values should this mechanism is recent evidence showing that 4 be maintained for only short periods of time. It is also weeks of b-alanine supplementation reduced the recommended that athletes undertake body fat and decline of blood pH during intense exercise (Baguet, body weight reduction under the supervision of an Koppo, Pottier, & Derave, 2010). The contribution expert dietitian/physiologist. of normal muscle carnosine to total intracellular muscle buffering capacity has been suggested to be *7%, but can reach *15% after b-alanine supple- Ergogenic supplements for power sports mentation (Harris et al., 2006). Most power sports are fuelled primarily by glycolysis Harris and colleagues (2006) were the first to show (Table I), resulting in a large production of lactate increases in muscle carnosine after prolonged b- and hydrogen ions (Hþ). These large increases in Hþ alanine supplementation in humans. All subsequent can cause decreases in muscle pH, from resting supplementation studies have shown a significant values of *7.1 down to *6.4 at exhaustion. increase in muscle carnosine concentrations utilizing Although fatigue is multi-factorial, the primary causes approximately 3–6 g of b-alanine per day over 4–8 of exhaustion during intense exercise lasting 1 to weeks (Derave et al., 2010). On average, this has led 10 min involves limitations imposed by non-oxida- to a significant (40–50%) increase in muscle carno- tive glycolysis, as well as negative consequences sine. A direct linear correlation has also been shown Downloaded by [University of California Santa Cruz] at 16:21 14 October 2011 resulting from the associated muscular acidosis and between the amount of b-alanine consumed (total ionic disturbances. This drop in muscular pH has grams) and the percent increase in muscle carnosine been shown to negatively affect metabolic processes, (R ¼ 0.569; P 5 0.01; unpublished observations). including disturbances of the creatine-phosphagen The washout of augmented skeletal muscle carnosine equilibrium, limiting the resynthesis of phosphagen, is slow, with an estimated washout time of 10–15 as well as the inhibition of glycolysis and the muscle weeks after a *50% increase in muscle carnosine contraction process itself (Hultman & Sahlin, 1980). (Baguet et al., 2009; Stellingwerff et al., 2010). During high-intensity exercise, many different Although some studies have not found enhanced innate metabolic processes and physico-chemical performance resulting from prolonged b-alanine properties contribute to both intracellular and extra- supplementation, several well-controlled studies cellular buffering capacity in attempts to maintain have demonstrated significant high-intensity (about intramuscular pH, with intramuscular carnosine and 1–6 min) performance benefits using both cycling plasma bicarbonate playing primary roles. Accord- and rowing protocols, as well as showing improved ingly, there are two supplements that power athletes isokinetic knee-extension performance (Artioli et al., can potentially utilize to augment buffering capacity, 2010; Derave et al., 2010). Studies not demonstrat- and potentially improve performance: (1) the pro- ing positive performance effects are most likely due Nutrition for power sports 9

to inadequate b-alanine dosing, not using well- NaHCO3 to improve intense exercise performance in trained and motivated participants, or being under- situations lasting from about 1 to 5 min or during powered and/or using inappropriately designed repeated sprints, with less pronounced effects on performance tests in which acid–base perturbations single sprints (550 s) or longer exercise duration are not limiting the outcome. Taken together, the (45 min). The only meta-analysis conducted ex- emerging data reveal that consumption of about 3– amining the performance effects of NaHCO3 found 6gb-alanine day71 over 4–8 weeks (for a total b- that supplementation resulted in a performance alanine intake of 4120 g) will result in an increase of effect that was 0.44 standard deviations better than muscle carnosine of about 40–50%, and, given a the control trial (Matson & Tran, 1993). An correctly designed performance test, will lead to improvement of 0.44 of the standard deviation would positive anaerobic performance outcomes in intense result in a modest *0.8 s improvement over a race exercise lasting 1–6 min. At this point, it remains to of about 1 min 45 s (e.g. 800 m), which for world- be established whether prolonged b-alanine supple- class athletes is within the worthwhile range of mentation can enhance weight training, sprint improvement. Nevertheless, there are many incon- (515 s) or endurance (420 min) performance. sistencies in the literature regarding whether NaH- CO3 can improve performance, with the main reasons including studies that did not use an Extracellular buffering: Sodium bicarbonate and citrate optimum performance test, bicarbonate dose, nega- During intense exercise, lactate and Hþ are trans- tive individual gastrointestinal responses, or were ported out of the muscle via monocarboxylate drastically under-powdered. Sodium citrate inges- transporters (primarily MCT-4) to the extracellular tion appears to result in lower buffering and space. Since hydrogen ions are transported against a performance effects than sodium bicarbonate (Van concentration gradient, any mechanism to increase Montfoort, Van Dieren, Hopkins, & Shearman, the rate of Hþ release from the muscle will help 2004). Furthermore, in the studies that have maintain muscle pH and delay fatigue. One such monitored body weight, it appears that both NaH- mechanism is an increase in the plasma bicarbonate CO3 and citrate cause a small (about 1–2%) increase þ (HCO3–) pool, which combines with the H to form in body weight, which could potentially diminish carbonic acid (H2CO3), which in turn dissociates to performance benefits in events that are more weight form carbon dioxide and water. Supplementation of dependent (running) versus less weight dependent sodium bicarbonate (NaHCO3) can lead to in- (cycling, rowing). Taken together, athletes and creased plasma bicarbonate and increased buffering coaches need to experiment with NaHCO3 in by improving the rate of Hþ release from active practice and low key competitions to ascertain skeletal muscle. individual water retention, body weight gains, and A series of studies throughout the 1980s found gastrointestinal effects, before use in major cham- that the optimum dosing regimen to augment the pionships. blood’s buffering capacity is via the supplementation of NaHCO (*300 mg kg BW71; *20 g) in the 1– 3 New horizons for buffers: Buffer combinations and 3 h before a high-intensity event (about 1–6 min; training effects McNaughton, 2000). However, there is a high degree of individual tolerance and variability, as Given the different mechanisms involved in intra- ingestion of water with the NaHCO3 causes a 1–2% and extracellular buffering, it could be hypothesized Downloaded by [University of California Santa Cruz] at 16:21 14 October 2011 increase in body weight and can cause significant that an additive effect on buffering and performance gastrointestinal upset in *50% of individuals. This could be found with chronic b-alanine supplementa- can be partially circumvented by supplementing the tion, coupled with acute pre-exercise NaHCO3 active dose of NaHCO3 in multiple gelatin capsules, supplementation. Indeed, this was found in a recent with significantly less water (Galloway & Maughan, report, in which cycling capacity at 110% of 1996). A recent study that systematically manipu- maximum power was improved to a greater extent lated the timing and type of bicarbonate supplemen- with a combined buffering approach than with acute tation protocols (capsules versus powder) found that NaHCO3 or chronic b-alanine supplementation the most effective strategy to increase plasma alone (Sale et al., 2010). bicarbonate concentrations involved the use of Also, a previous study found positive effects of bicarbonate capsules consumed in serial doses over utilizing acute NaHCO3 supplementation before a period of 120–150 min before exercise and co- intense interval training (three times a week for 8 ingested with a high-carbohydrate meal or snack weeks) in moderately trained females (Edge, Bishop, (Carr, Slater, Gore, Dawson, & Burke, 2011). & Goodman, 2006). In this study, the group When utilizing the ideal NaHCO3 dosing regimen, supplemented with NaHCO3 had larger training there appears to be a small but significant effect of improvements in lactate threshold and endurance 10 T. Stellingwerff et al.

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