There is little information describing how endurance athletes perceive sodium intake in relation to training and competition. Using an online questionnaire, this study assessed the beliefs, information sources, and intended practices regarding sodium ingestion for training and competition. Endurance athletes (n = 344) from six English-speaking countries completed the questionnaire and were included for analysis. The most cited information sources were social supports (63%), self-experimentation (56%), and media (48%). Respondents generally believed (>50% on electronic visual analog scale) endurance athletes require additional sodium on a daily basis (median 67% [interquartile range: 40–81%]), benefit from increased sodium in the days preceding competition (60% [30–77%]), should replace sodium losses during training (69% [48–83%]) and competition (74% [54–87%]), and would benefit from sweat composition testing (82% [65–95%]). Respondents generally believed sodium ingestion during endurance exercise prevents exercise-associated muscle cramps (75% [60–88%]) and exercise-associated hyponatremia (74% [62–89%]). The majority (58%) planned to consciously increase sodium or total food intake (i.e., indirectly increasing sodium intake) in the days preceding competition. Most (79%) were conscious of sodium intake during competition, but only 29% could articulate a specific intake plan. A small minority (5%) reported using commercial sweat testing services, of which 75% believed it was beneficial. We conclude that endurance athletes commonly perceive sodium intake as important for their sporting activities. Many intend to consciously increase sodium intake in the days preceding and during competition, although these views appear informed mostly by nonscientific and/or non-evidence-based sources.
Alan J. McCubbin, Gregory R. Cox, and Ricardo J.S. Costa
Alan J. McCubbin, Gregory R. Cox, and Elizabeth M. Broad
This case study describes the nutrition plans, intakes and experiences of five ultra-marathon runners who completed the Marathon des Sables in 2011 and 2013; age 37 (28–43) y, height 184 (180–190) cm, body mass 77.5 (71–85.5) kg, marathon personal best 3:08 (2:40–3:32). MdS is a 7-day, six-stage ultra-running stage race held in the Sahara Desert (total distance of timed stages 1–5 was 233.2 km in 2011, 223.4 km in 2013). Competitors are required to carry all equipment and food (except water) for the race duration, a minimum of 8,360 kJ/day and total pack weight of 6.5–15 kg. Total food mass carried was 4.2 (3.8–4.7) kg or 0.7 (0.5–1.1) kg/day. Planned energy (13,550 (10,323–18,142) kJ/day), protein (1.3 (0.8–1.8) g/kg/day), and carbohydrate (6.2 (4.3–9.2) g/kg/day) intakes on the fully self-sufficient days were slightly below guideline recommendations, due to the need to balance nutritional needs with food mass to be carried. Energy density was 1,636 (1,475–1,814) kJ/100g. 98.5% of the planned food was consumed. Fluid consumption was ad libitum with no symptoms or medical treatment required for dehydration or hyponatremia. During-stage carbohydrate intake was 42 (20–64) g/hour. Key issues encountered by runners included difficulty consuming foods due to dry mouth, and unpalatability of sweet foods (energy gels, sports drinks) when heated in the sun. Final classification of the runners ranged from 11th to 175th of 970 finishers in 2013, and 132nd of 805 in 2011. The described pattern of intake and macronutrient quantities were positively appraised by the five runners.
Siobhan T. Moran, Christine E. Dziedzic, and Gregory R. Cox
The aim of this case study was to describe the race nutrition practices of a female runner who completed her first 100-km off-road ultraendurance running event in 12 hr 48 min 55 s. Food and fluid intake during the race provided 10,890 kJ (736 kJ/hr) and 6,150 ml (415 ml/hr) of fluid. Hourly reported carbohydrate intake was 44 g, with 34% provided by sports drink. Hourly carbohydrate intake increased in the second half (53 g/hr) compared with the first half (34 g/h) of the race, as the athlete did not have access to individualized food and fluid choices at the early checkpoints and felt satiated in the early stages of the race after consuming a prerace breakfast. Mean sodium intake was 500 mg/hr (52 mmol/L), with a homemade savory broth and sports drink (Gatorade Endurance) being the major contributors. The athlete consumed a variety of foods of varying textures and tastes with no complaints of gastrointestinal discomfort. Despite thinking she would consume sweet foods exclusively, as she had done in training, the athlete preferred savory foods and fluids at checkpoints during the latter stages of the race. This case study highlights the importance of the sports nutrition team in educating athletes about race-day nutrition strategies and devising a simple yet effective system to allow them to manipulate their race-day food and fluid intake to meet their nutritional goals.
Peter Peeling, Gregory R. Cox, Nicola Bullock, and Louise M. Burke
We assessed the ingestion of a beetroot juice supplement (BR) on 4-min laboratory-based kayak performance in national level male (n = 6) athletes (Study A), and on 500 m on-water kayak time-trial (TT) performance in international level female (n = 5) athletes (Study B). In Study A, participants completed three laboratory-based sessions on a kayak ergometer, including a 7 × 4 min step test, and two 4 min maximal effort performance trials. Two and a half hours before the warm-up of each 4 min performance trial, athletes received either a 70 ml BR shot containing ~4.8 mmol of nitrate, or a placebo equivalent (BRPLA). The distance covered over the 4 min TT was not different between conditions; however, the average VO2 over the 4 min period was significantly lower in BR (p = .04), resulting in an improved exercise economy (p = .05). In Study B, participants completed two field-based 500 m TTs, separated by 4 days. Two hours before each trial, athletes received either two 70 ml BR shots containing ~9.6 mmol of nitrate, or a placebo equivalent (BRPLA). BR supplementation significantly enhanced TT performance by 1.7% (p = .01). Our results show that in national-level male kayak athletes, commercially available BR shots (70 ml) containing ~4.8 mmol of nitrate improved exercise economy during laboratory-based tasks predominantly reliant on the aerobic energy system. Furthermore, greater volumes of BR (140 ml; ~9.6 mmol nitrate) provided to international-level female kayak athletes resulted in enhancements to TT performance in the field.
Dan Benardot, Wes Zimmermann, Gregory R. Cox, and Saul Marks
Competitive diving involves grace, power, balance, and flexibility, which all require satisfying daily energy and nutrient needs. Divers are short, well-muscled, and lean, giving them a distinct biomechanical advantage. Although little diving-specific nutrition research on performance and health outcomes exists, there is concern that divers are excessively focused on body weight and composition, which may result in reduced dietary intake to achieve desired physique goals. This will result in low energy availability, which may have a negative impact on their power-to-weight ratio and health risks. Evidence is increasing that restrictive dietary practices leading to low energy availability also result in micronutrient deficiencies, premature fatigue, frequent injuries, and poor athletic performance. On the basis of daily training demands, estimated energy requirements for male and female divers are 3,500 kcal and 2,650 kcal, respectively. Divers should consume a diet that provides 3–8 g/kg/day of carbohydrate, with the higher values accommodating growth and development. Total daily protein intake (1.2–1.7 g/kg) should be spread evenly throughout the day in 20 to 30 g amounts and timed appropriately after training sessions. Divers should consume nutrient-dense foods and fluids and, with medical supervision, certain dietary supplements (i.e., calcium and iron) may be advisable. Although sweat loss during indoor training is relatively low, divers should follow appropriate fluid-intake strategies to accommodate anticipated sweat losses in hot and humid outdoor settings. A multidisciplinary sports medicine team should be integral to the daily training environment, and suitable foods and fluids should be made available during prolonged practices and competitions.
Gregory R. Cox, Iñigo Mujika, and Cees-Rein van den Hoogenband
Water polo is an aquatic team sport that requires endurance, strength, power, swimming speed, agility, tactical awareness, and specific technical skills, including ball control. Unlike other team sports, few researchers have examined the nutritional habits of water polo athletes or potential dietary strategies that improve performance in water polo match play. Water polo players are typically well muscled, taller athletes; female players display higher levels of adiposity compared with their male counterparts. Positional differences exist: Center players are heavier and have higher body fat levels compared with perimeter players. Knowledge of the physical differences that exist among water polo players offers the advantage of player identification as well as individualizing nutrition strategies to optimize desired physique goals. Individual dietary counseling is warranted to ensure dietary adequacy, and in cases of physique manipulation. Performance in games and during quality workouts is likely to improve by adopting strategies that promote high carbohydrate availability, although research specific to water polo is lacking. A planned approach incorporating strategies to facilitate muscle glycogen refueling and muscle protein synthesis should be implemented following intensified training sessions and matches, particularly when short recovery times are scheduled. Although sweat losses of water polo players are less than what is reported for land-based athletes, specific knowledge allows for appropriate planning of carbohydrate intake strategies for match play and training. Postgame strategies to manage alcohol intake should be developed with input from the senior player group to minimize the negative consequences on recovery and player welfare.
Reid Reale, Gregory R. Cox, Gary Slater, and Louise M. Burke
We examined the relationship between the regain of body mass (BM) after weigh-in and success in real-life judo competition. Eighty-six (36 females, 50 males) senior judoka volunteered for this observational study of an international judo competition. Subjects were weighed at the official weigh-in and one hour before their first competition fight (15–20 hr later). Regain in BM after weigh-in was compared between medal winners and nonmedalists, winners and losers of each fight, males and females and across weight divisions. Heavyweights were excluded from analysis. Prefight BM was greater than BM at official weigh-in for both males and females, with % BM gains of 2.3 ± 2.0 (p ≤ .0001; ES= 1.59; CI95% [1.63, 2.98]) and 3.1 ± 2.2 (p ≤ .0001; ES = 2.03; CI95% [2.30, 3.89]), respectively. No significant differences were found between weight divisions for post weigh-in BM regain. Differences in post weigh-in BM regain were significantly higher in medal winners than nonmedalists for males and females combined (1.4 ± 0.4% BM; p = .0026; ES= 0.69; CI95% [0.05, 2.34]) and for males alone (1.5 ± 0.6% BM; p = .017; ES= 0.74; CI95% [0.02, 2.64]), but not for females (1.2 ± 0.7% BM; p = .096; ES = 0.58; CI95% [-0.02, 2.31]). Differences in BM regain after weigh-in between winners and losers were significant across all fights (0.9 ± 0.3% BM; p = .0021; ES= 0.43; CI95% [0.31, 1.41]) but not for first round fights (0.8 ± 0.5% BM; p = .1386, ES = 0.38; CI95% [-0.26, 1.86]). Winners showed a greater regain in BM post weigh-in than losers. This may reflect the greater magnitude of the BM loss needed to achieve weigh-in targets which also relates to the experience level of successful athletes.
Reid Reale, Gregory R. Cox, Gary Slater, and Louise M. Burke
Combat-sport athletes acutely reduce body mass (BM) before weigh-in in an attempt to gain a size/strength advantage over smaller opponents. Few studies have investigated these practices among boxers and none have explored the impact of this practice on competitive success.
One hundred (30 women, 70 men) elite boxers participating in the Australian national championships were weighed at the official weigh-in and 1 h before each competition bout. Regain in BM after weigh-in was compared between finalists and nonfinalists, winners and losers of each fight, men and women, and weight divisions. Boxers were surveyed on their pre- and post-weigh-in nutrition practices.
The lightest men’s weight category displayed significantly greater relative BM regain than all other divisions, with no difference between other divisions. BM prebout was higher than official weigh-in for men (2.12% ± 1.62%; P < .001; ES = 0.13) and women (1.49% ± 1.65%; P < .001; ES = 0.11). No differences in BM regain were found between finalists and nonfinalists, winners and losers of individual bouts, or between preliminary or final bouts. BM regain was significantly greater (0.37% BM, P < .001; ES = 0.25) before an afternoon bout compared with a morning bout.
Boxers engage in acute BM-loss practices before the official competition weigh-in, but this does not appear to affect competition outcomes, at least when weight regain between weigh-in and fighting is used as a proxy for the magnitude of acute loss. While boxers recognize the importance of recovering after weigh-in, current practice is not aligned with best-practice guidance.
Gregory R. Cox, Rodney J. Snow, and Louise M. Burke
The aim of this study was to investigate the prerace and during-race carbohydrate intakes of elite-level triathletes contesting draft-legal Olympic-distance triathlon (ODT) events. Self-reported prerace and during-race nutrition data were collected at 3 separate ODT events from 51 elite senior and under-23 triathletes. One hundred twenty-nine observations of food and fluid intake representing actual prerace (n = 62) and during-race (n = 67) nutrition practices from 36 male and 15 female triathletes were used in the final analysis of this study. Female triathletes consumed significantly more carbohydrate on the morning before race start when corrected for body mass and race start time than their male counterparts (p < .05). Male and female triathletes consumed 26% more energy (kJ/kg) and 24% more carbohydrate (g/kg) when commencing a race after midday (1:00–1:30 p.m.) than for a late morning (11:00–11:15 a.m.) race start. During the race, triathletes consumed less than 60 g of carbohydrate on 66% of occasions, with average total race intakes of 48 ± 25 and 49 ± 25 g carbohydrate for men and women, respectively. Given average race times of 1:57:07 hr and 2:08:12 hr, hourly carbohydrate intakes were ~25 g and ~23 g for men and women, respectively. Although most elite ODT triathletes consume sufficient carbohydrate to meet recommended prerace carbohydrate intake guidelines, during-race carbohydrate intakes varied considerably, with many failing to meet recommended levels.
Thomas M. Doering, Peter R. Reaburn, Nattai R. Borges, Gregory R. Cox, and David G. Jenkins
Following exercise-induced muscle damage (EIMD), masters athletes take longer to recover than younger athletes. The purpose of this study was to determine the effect of higher than recommended postexercise protein feedings on the recovery of knee extensor peak isometric torque (PIT), perceptions of recovery, and cycling time trial (TT) performance following EIMD in masters triathletes. Eight masters triathletes (52 ± 2 y, V̇O2max, 51.8 ± 4.2 ml•kg-1•min-1) completed two trials separated by seven days in a randomized, doubleblind, crossover study. Trials consisted of morning PIT testing and a 30-min downhill run followed by an eight-hour recovery. During recovery, a moderate (MPI; 0.3 g•kg-1•bolus-1) or high (0.6 g•kg-1•bolus-1) protein intake (HPI) was consumed in three bolus feedings at two hour intervals commencing immediately postexercise. PIT testing and a 7 kJ•kg-1 cycling TT were completed postintervention. Perceptions of recovery were assessed pre- and postexercise. The HPI did not significantly improve recovery compared with MPI (p > .05). However, comparison of within-treatment change shows the HPI provided a moderate beneficial effect (d = 0.66), attenuating the loss of afternoon PIT (-3.6%, d = 0.09) compared with the MPI (-8.6%, d = 0.24). The HPI provided a large beneficial effect (d = 0.83), reducing perceived fatigue over the eight-hour recovery (d = 1.25) compared with the MPI (d = 0.22). Despite these effects, cycling performance was unchanged (HPI = 2395 ± 297 s vs. MPI = 2369 ± 278 s; d = 0.09). In conclusion, doubling the recommended postexercise protein intake did not significantly improve recovery in masters athletes; however, HPI provided moderate to large beneficial effects on recovery that may be meaningful following EIMD.