Principles of Sports Nutrition
Elizabeth Broad in Sports Nutrition for Paralympic Athletes, 2019
Good drink choices will depend on the sport and on other nutritional goals that might be important. First, a fluid needs to be palatable and available to encourage intake. However other characteristics include temperature (Burdon et al. 2010, 2012), which can be manipulated both to enhance palatability in the specific environment and to contribute to body temperature regulation (cold fluids and ice slurries can reduce core temperature in hot conditions, while warm fluids may increase body temperature losses in cold environments). Second, there is the opportunity for a drink to contain other nutrients that might enhance performance, such as carbohydrate (Jeukendrup 2010; Jeukendrup and Chambers 2010) or caffeine (Burke 2008). Sports drinks which are formulated to meet a range of needs provide carbohydrate and electrolytes, with the latter encouraging fluid intake by maintaining thirst.
Dehydration and the Young Athlete
Flavia Meyer, Zbigniew Szygula, Boguslaw Wilk in Fluid Balance, Hydration, and Athletic Performance, 2016
An understanding of the amount, type, flavor, and temperature of fluids that promote an adequate intake in young athletes is needed to optimize their hydration regimes. In addition to plain water, young athletes consume a variety of beverages during exercise including sodas, fruit juices, enhanced water, milk, energy drinks, and sports drinks. Sodas and fruit juices are not recommended during exercise because of their high sugar content and carbonation which take longer to empty from the stomach and can cause stomach upset and interfere with proper hydration. Enhanced waters usually contain vitamins that are not necessary during exercise. Low-fat milk is effective for post-exercise fluid replacement because of its protein and electrolyte content that promotes fluid retention (Volterman et al. 2014). Energy drinks have become popular with high school students. They contain a large dose of caffeine which can have a greater stimulant effect in youngsters compared to adults. Often young athletes are not aware of the differences between sports and energy drinks and they consume energy drinks when their goal is to rehydrate. The American Academy of Pediatrics (2011b) and the Institute of Medicine (2014) have advised against their use in children and adolescents due to potential health risks due to their stimulant content.
Nutrition for health and sports performance
Nick Draper, Helen Marshall in Exercise Physiology, 2014
Calorie intake to maintain a balance between input and expenditure is highly individual and is dependent on factors such as age, gender, body size and composition, frequency, intensity and duration of training, and individual metabolic differences. Calorie intake should be matched to energy requirements to maintain a healthy body composition. Maintaining fluid balance, as well as nutritional balance, is vital for health and sports performance. For general health, water should ideally be consumed in small quantities at regular intervals throughout the day, such as continuous sipping from a water bottle. Similarly, during sporting activities, it is recommended that fluid should be drunk regularly (every 15–20 minutes) in small volumes (around 200 ml). This is feasible in some activities, such as cycling and running; however, other sports are limited to drinking during breaks in play (e.g. soccer, rugby, netball, field hockey). Water is generally the best form of fluid to maintain euhydration during the day. Sports drinks, containing carbohydrates and electrolytes, may be beneficial during and post exercise as not only do they provide a rapid energy supply, but the presence of electrolytes and glucose increases the speed at which fluid enters the blood. Fluid replacement, however, can be achieved almost as quickly by drinking plain water, and at a fraction of the cost.
Effects of air-perfused rucksack on physiological and perceptual strain during low-intensity exercise in a hot environment
Published in Temperature, 2020
Masanobu Kajiki, Naoyuki Yamashita, Ryo Ito, Takaaki Matsumoto
All participants performed two trials with (FAN) and without (CON) the fan cooling device, respectively, in a randomized, counterbalanced order, separated by at least 5 days to minimize carryover effects because of exercise in a hot environment. Trials were conducted at the same time of day to minimize the effect of circadian rhythm. Participants wore an identical 100% polyester T-shirt, running shorts, and running shoes during the two trials. The rucksack was placed over the T-shirt in the FAN trial. All experimental sessions were performed in a climate chamber (35°C, 50% relative humidity [RH]) (TBR-12A4PX; ESPEC, Osaka, Japan). The participants walked on a treadmill (BM-1200; S&ME, Tokyo, Japan) at 5.5 km/h (2.0% gradient) for 60 min. Upon arrival at the laboratory, participants were instructed to empty their bladder. They then drank a sports drink (200 ml, 4 °C) to avoid dehydration, and their body mass was measured. After placement of rectal and skin thermistors and the HR sensor, the participants entered the climate chamber and rested on a chair for >10 min. The participants then put on the air-perfused rucksack, and the two fans were turned on just before the start of walking. The participants walked at a constant intensity (5.5 km/h, 2.0% gradient) for 60 min. At 30 min and 60 min after the beginning of walking, the participants drank a sports drink (200 ml, 4 °C). After exercise, they rested on a chair for 20 min. Their body mass was measured after the rectal and skin thermistors and the HR sensor were removed.
Physiological demands and nutritional considerations for Olympic-style competitive rock climbing
Published in Cogent Medicine, 2019
Marisa K. Michael, Oliver C. Witard, Lanae Joubert
The carbohydrate requirements of rock climbers are likely less than endurance athletes due to the comparatively low energy demands of climbing. Estimated carbohydrate needs are in the range of ~3–7 g/kg BM/day, and ~20–30 g/h during a climbing session, with a carbohydrate intake of ~5 g/kg BM/day for multiple speed climbing sets (Joubert, Larson, & Weber, 2016). Carbohydrate-containing sports drinks may contribute to this overall daily carbohydrate recommendation. Simple carbohydrates that are readily absorbed and easily digested are advisable before and during active climbing to minimize gastrointestinal distress and maximize fuel availability. Support for this recommendation stems from previous research with intermittent sport activities showing increased exercise capacity with carbohydrate ingestion (Baker et al., 2015). Slower-release carbohydrates containing more fiber, coupled with protein, may be useful in boulderers and lead climbers, especially for an all-day training or competition (Baker et al., 2015). Smith et al. (2017) recommends a carbohydrate intake of 1 g/kg BM immediately prior to competition for boulderers. For multi-day competitions, carbohydrate intake should be optimized to replenish muscle glycogen stores at the end of each day. Carbohydrate recommendations of 0.8–1.2 g/kg BM/hr, and a per serving protein of 0.3 g/kg BM during the early recovery period has been suggested to enhance muscle recovery (Sousa, Teixeirea, & Soares, 2014).
Effects of training intensity and environmental condition on the hydration status of elite football players
Published in Science and Medicine in Football, 2020
Vlad Sabou, Chris Rush, Liam Mason, Grégory Dupont, Julien Louis
The players were weighted wearing only underpants before and after the training sessions using the same scale (Seca 875, Hamburg, Germany) they used at the club. Sweat loss was calculated based on changes in body mass after correction for fluid intake. Players were asked to urinate and defecate prior to the pre-training measurements. No player urinated during any of the three training sessions. Each player was provided with one 800 ml bottle of water and one 800 ml bottle of in-house made sport drink (400 mg Na+, 0 kcal, 0 g carbohydrates) to drink during the training sessions. Bottles were weighted using a kitchen scale (Kern, type C, Balingen, Germany) before they were provided to the players and after the training sessions to assess fluid intake. Additional bottles were available for the players during training if required. Habitual hydration practices during training sessions were maintained, with no extra encouragement nor recommendation given to the players regarding fluid intake.
Related Knowledge Centers
- Endurance Training
- Food Energy
- Glycogen
- Milk
- Muscle
- Hyponatremia
- Electrolyte
- Sugar
- Fluid Replacement
- Weight Gain