myofibrillar protein synthesis . The Journal of Physiology, 591 , 2319 – 2331 . PubMed ID: 23459753 doi:10.1113/jphysiol.2012.244897 10.1113/jphysiol.2012.244897 Bartlett , J.D. , Hawley , J.A. , & Morton , J.P. ( 2015 ). Carbohydrate availability and exercise training adaptation: Too much of a
Samuel G. Impey, Kelly M. Hammond, Robert Naughton, Carl Langan-Evans, Sam O. Shepherd, Adam P. Sharples, Jessica Cegielski, Kenneth Smith, Stewart Jeromson, David L. Hamilton, Graeme L. Close and James P. Morton
Sally P. Waterworth, Connor C. Spencer, Aaron L. Porter and James P. Morton
during endurance exercise in humans: A meta-analysis . Sports Medicine, 48 ( 9 ), 2091 – 2102 . PubMed ID: 29923148 doi:10.1007/s40279-018-0941-1 10.1007/s40279-018-0941-1 Bartlett , J.D. , Hawley , J.A. , & Morton , J.P. ( 2015 ). Carbohydrate availability and exercise training adaptation
Joanne G. Mirtschin, Sara F. Forbes, Louise E. Cato, Ida A. Heikura, Nicki Strobel, Rebecca Hall and Louise M. Burke
nutrition. References Bartlett , J.D. , Hawley , J.A. , & Morton , J.P. ( 2015 ). Carbohydrate availability and exercise training adaptation: Too much of a good thing? European Journal of Sport Science, 15 , 3 – 12 . PubMed ID: 24942068 doi:10.1080/17461391.2014.920926 10
Andrew J.R. Cochran, Frank Myslik, Martin J. MacInnis, Michael E. Percival, David Bishop, Mark A. Tarnopolsky and Martin J. Gibala
Commencing some training sessions with reduced carbohydrate (CHO) availability has been shown to enhance skeletal muscle adaptations, but the effect on exercise performance is less clear. We examined whether restricting CHO intake between twice daily sessions of high-intensity interval training (HIIT) augments improvements in exercise performance and mitochondrial content. Eighteen active but not highly trained subjects (peak oxygen uptake [VO2peak] = 44 ± 9 ml/kg/min), matched for age, sex, and fitness, were randomly allocated to two groups. On each of 6 days over 2 weeks, subjects completed two training sessions, each consisting of 5 × 4-min cycling intervals (60% of peak power), interspersed by 2 min of recovery. Subjects ingested either 195 g of CHO (HI-HI group: ~2.3 g/kg) or 17 g of CHO (HI-LO group: ~0.3 g/kg) during the 3-hr period between sessions. The training-induced improvement in 250-kJ time trial performance was greater (p = .02) in the HI-LO group (211 ± 66 W to 244 ± 75 W) compared with the HI-HI group (203 ± 53 W to 219 ± 60 W); however, the increases in mitochondrial content was similar between groups, as reflected by similar increases in citrate synthase maximal activity, citrate synthase protein content and cytochrome c oxidase subunit IV protein content (p > .05 for interaction terms). This is the first study to show that a short-term “train low, compete high” intervention can improve whole-body exercise capacity. Further research is needed to determine whether this type of manipulation can also enhance performance in highly-trained subjects.
Ida A. Heikura, Trent Stellingwerff, Antti A. Mero, Arja Leena Tuulia Uusitalo and Louise M. Burke
Contemporary nutrition guidelines promote a variety of periodized and time-sensitive recommendations, but current information regarding the knowledge and practice of these strategies among world-class athletes is limited. The aim of this study was to investigate this theme by implementing a questionnaire on dietary periodization practices in national/international level female (n = 27) and male (n = 21) middle- and long-distance runners/race-walkers. The questionnaire aimed to gain information on between and within-day dietary choices, as well as timing of pre- and posttraining meals and practices of training with low or high carbohydrate (CHO) availability. Data are shown as percentage (%) of all athletes, with differences in responses between subgroups (sex or event) shown as Chi-square x2 when p < .05. Nearly two-thirds of all athletes reported that they aim to eat more food on, or after, hard training days. Most athletes said they focus on adequate fueling (96%) and adequate CHO and protein (PRO) recovery (87%) around key sessions. Twenty-six percent of athletes (11% of middle vs 42% of long-distance athletes [x 2 (1, n = 46) = 4.308, p = .038, phi = 0.3])) reported to undertake training in the fasted state, while 11% said they periodically restrict CHO intake, with 30% ingesting CHO during training sessions. Our findings show that elite endurance athletes appear to execute pre- and post-key session nutrition recovery recommendations. However, very few athletes deliberately undertake some contemporary dietary periodization approaches, such as training in the fasted state or periodically restricting CHO intake. This study suggests mismatches between athlete practice and current and developing sports nutrition guidelines.
Trent Stellingwerff, James P. Morton and Louise M. Burke
:10.1007/s40279-018-0941-1 10.1007/s40279-018-0941-1 Bartlett , J.D. , Louhelainen , J. , Iqbal , Z. , Cochran , A.J. , Gibala , M.J. , Gregson , W. , … Morton , J.P. ( 2013 ). Reduced carbohydrate availability enhances exercise-induced p53 signaling in human skeletal muscle
Gary J. Slater, Jennifer Sygo and Majke Jorgensen
–18 years Adolescent ( n = 26) 55 8.4 ± 1.6 153 273 ± 54 5.1 ± 1.1 78 ± 15 1.5 ± 0.3 69 ± 17 30 ± 5 7-Day diary Aerenhouts et al. ( 2008 ) Carbohydrate The ergogenic potential of carbohydrate availability for sprint athletes is poorly understood. There is evidence that maintenance of an extremely low
Peter W.R. Lemon
This paper reviews the factors (exercise intensity, carbohydrate availability, exercise type, energy balance, gender, exercise training, age, and timing of nutrient intake or subsequent exercise sessions) thought to influence protein need. Although there remains some debate, recent evidence suggests that dietary protein need increases with rigorous physical exercise. Those involved in strength training might need to consume as much as 1.6 to 1.7 g protein ⋅ kg−1 day−1 (approximately twice the current RDA) while those undergoing endurance training might need about 1.2 to 1.4 g ⋅ kg−1 day−1 (approximately 1.5 times the current RDA). Future longitudinal studies are needed to confirm these recommendations and assess whether these protein intakes can enhance exercise performance. Despite the frequently expressed concern about adverse effects of high protein intake, there is no evidence that protein intakes in the range suggested will have adverse effects in healthy individuals.
Tzai-Li Li and Michael Gleeson
This study compared immunoendocrine responses to a single bout of prolonged cycling at different times of day and to a 2nd bout of cycling at the same intensity on the same day. In a counterbalanced design, 8 men participated in 3 experimental trials separated by at least 4 d. In the afternoon exercise-only trial, subjects cycled for 2 h at 60% VO2max starting at 14:00. In the other 2 trials, subjects performed either 2 bouts of cycling at 60% VO2max for 2 h (starting at 09:00 and 14:00) or a separate resting trial. The single bout of prolonged exercise performed in the afternoon induced a larger neutrophilia and monocy-tosis than the identical bout of morning exercise, possibly the result of reduced carbohydrate availability and the circadian rhythm in cortisol levels. The 2nd prolonged exercise bout caused greater immunoendocrine responses but lower plasma glucose levels and neutrophil function compared with the 1st bout.
Edward J. Smith, Ryan Storey and Mayur K. Ranchordas
Bouldering competitions are held up to International level and governed by the International Federation of Sport Climbing. Bouldering has been selected to feature at the 2020 Olympic Games in Tokyo, however, physiological qualities and nutritional requirements to optimize performance remain inadequately defined due to large gaps in the literature. The primary goals of training include optimizing the capacity of the anaerobic energy systems and developing sport-specific strength, with emphasis on the isometric function of the forearm flexors responsible for grip. Bouldering athletes typically possess a lean physique, similar to the characteristics of sport climbers with reported body fat values of 6–12%. Athletes strive for a low body weight to improve power to weight ratio and limit the load on the extremities. Specialized nutritional support is uncommon and poor nutritional practices such as chronic carbohydrate restriction are prevalent, compromising the health of the athletes. The high intensity nature of bouldering demands a focus on adequate carbohydrate availability. Protein intake and timing should be structured to maximize muscle protein synthesis and recovery, with the literature suggesting 0.25–0.3 g/kg in 3–4 hr intervals. Supplementing with creatine and b-alanine may provide some benefit by augmenting the capacity of the anaerobic systems. Boulderers are encouraged to seek advice from nutrition experts to enhance performance, particularly important when weight loss is the desired outcome. Further research is warranted across all nutritional aspects of bouldering which is summarized in this review.