Alannah K.A. McKay, Peter Peeling, David B. Pyne, Nicolin Tee, Marijke Welveart, Ida A. Heikura, Avish P. Sharma, Jamie Whitfield, Megan L. Ross, Rachel P.L. van Swelm, Coby M. Laarakkers, and Louise M. Burke
This study implemented a 2-week high carbohydrate (CHO) diet intended to maximize CHO oxidation rates and examined the iron-regulatory response to a 26-km race walking effort. Twenty international-level, male race walkers were assigned to either a novel high CHO diet (MAX = 10 g/kg body mass CHO daily) inclusive of gut-training strategies, or a moderate CHO control diet (CON = 6 g/kg body mass CHO daily) for a 2-week training period. The athletes completed a 26-km race walking test protocol before and after the dietary intervention. Venous blood samples were collected pre-, post-, and 3 hr postexercise and measured for serum ferritin, interleukin-6, and hepcidin-25 concentrations. Similar decreases in serum ferritin (17–23%) occurred postintervention in MAX and CON. At the baseline, CON had a greater postexercise increase in interleukin-6 levels after 26 km of walking (20.1-fold, 95% CI [9.2, 35.7]) compared with MAX (10.2-fold, 95% CI [3.7, 18.7]). A similar finding was evident for hepcidin levels 3 hr postexercise (CON = 10.8-fold, 95% CI [4.8, 21.2]; MAX = 8.8-fold, 95% CI [3.9, 16.4]). Postintervention, there were no substantial differences in the interleukin-6 response (CON = 13.6-fold, 95% CI [9.2, 20.5]; MAX = 11.2-fold, 95% CI [6.5, 21.3]) or hepcidin levels (CON = 7.1-fold, 95% CI [2.1, 15.4]; MAX = 6.3-fold, 95% CI [1.8, 14.6]) between the dietary groups. Higher resting serum ferritin (p = .004) and hotter trial ambient temperatures (p = .014) were associated with greater hepcidin levels 3 hr postexercise. Very high CHO diets employed by endurance athletes to increase CHO oxidation have little impact on iron regulation in elite athletes. It appears that variations in serum ferritin concentration and ambient temperature, rather than dietary CHO, are associated with increased hepcidin concentrations 3 hr postexercise.
Oliver C. Witard, Laurent Bannock, and Kevin D. Tipton
The acute response of muscle protein synthesis (MPS) to resistance exercise and nutrition is often used to inform recommendations for exercise programming and dietary interventions, particularly protein nutrition, to support and enhance muscle growth with training. Those recommendations are worthwhile only if there is a predictive relationship between the acute response of MPS and subsequent muscle hypertrophy during resistance exercise training. The metabolic basis for muscle hypertrophy is the dynamic balance between the synthesis and degradation of myofibrillar proteins in muscle. There is ample evidence that the process of MPS is much more responsive to exercise and nutrition interventions than muscle protein breakdown. Thus, it is intuitively satisfying to translate the acute changes in MPS to muscle hypertrophy with training over a longer time frame. Our aim is to examine and critically evaluate the strength and nature of this relationship. Moreover, we examine the methodological and physiological factors related to measurement of MPS and changes in muscle hypertrophy that contribute to uncertainty regarding this relationship. Finally, we attempt to offer recommendations for practical and contextually relevant application of the information available from studies of the acute response of MPS to optimize muscle hypertrophy with training.
Kobe C. Houtmeyers, Arne Jaspers, and Pedro Figueiredo
Elite sport practitioners increasingly use data to support training process decisions related to athletes’ health and performance. A careful application of data analytics is essential to gain valuable insights and recommendations that can guide decision making. In business organizations, data analytics are developed based on conceptual data analytics frameworks. The translation of such a framework to elite sport may benefit the use of data to support training process decisions. Purpose: The authors aim to present and discuss a conceptual data analytics framework, based on a taxonomy used in business analytics literature to help develop data analytics within elite sport organizations. Conclusions: The presented framework consists of 4 analytical steps structured by value and difficulty/complexity. While descriptive (step 1) and diagnostic analytics (step 2) focus on understanding the past training process, predictive (step 3) and prescriptive analytics (step 4) provide more guidance in planning the future. Although descriptive, diagnostic, and predictive analytics generate insights to inform decisions, prescriptive analytics can be used to drive decisions. However, the application of this type of advanced analytics is still challenging in elite sport. Thus, the current use of data in elite sport is more focused on informing decisions rather than driving them. The presented conceptual framework may help practitioners develop their analytical reasoning by providing new insights and guidance and may stimulate future collaborations between practitioners, researchers, and analytics experts.
Philip Friere Skiba and David C. Clarke
Since its publication in 2012, the W′ balance model has become an important tool in the scientific armamentarium for understanding and predicting human physiology and performance during high-intensity intermittent exercise. Indeed, publications featuring the model are accumulating, and it has been adapted for popular use both in desktop computer software and on wrist-worn devices. Despite the model’s intuitive appeal, it has achieved mixed results thus far, in part due to a lack of clarity in its basis and calculation. Purpose: This review examines the theoretical basis, assumptions, calculation methods, and the strengths and limitations of the integral and differential forms of the W′ balance model. In particular, the authors emphasize that the formulations are based on distinct assumptions about the depletion and reconstitution of W′ during intermittent exercise; understanding the distinctions between the 2 forms will enable practitioners to correctly implement the models and interpret their results. The authors then discuss foundational issues affecting the validity and utility of the model, followed by evaluating potential modifications and suggesting avenues for further research. Conclusions: The W′ balance model has served as a valuable conceptual and computational tool. Improved versions may better predict performance and further advance the physiology of high-intensity intermittent exercise.
Sabrina Skorski and Anne Hecksteden
Heitor O. Santos, Gederson K. Gomes, Brad J. Schoenfeld, and Erick P. de Oliveira
Whole egg may have potential benefits for enhancing muscle mass, independent of its protein content. The yolk comprises ∼40% of the total protein in an egg, as well as containing several nonprotein nutrients that could possess anabolic properties (e.g., microRNAs, vitamins, minerals, lipids, phosphatidic acid and other phospholipids). Therefore, the purpose of this narrative review is to discuss the current evidence as to the possible effects of egg yolk compounds on skeletal muscle accretion beyond those of egg whites alone. The intake of whole egg seems to promote greater myofibrillar protein synthesis than egg white intake in young men. However, limited evidence shows no difference in muscle hypertrophy when comparing the consumption of whole egg versus an isonitrogenous quantity of egg white in young men performing resistance training. Although egg yolk intake seems to promote additional acute increases on myofibrillar protein synthesis, it does not seem to further enhance muscle mass when compared to egg whites when consumed as part of a high-protein dietary patterns, at least in young men. This conclusion is based on very limited evidence and more studies are needed to evaluate the effects of egg yolk (or whole eggs) intake on muscle mass not only in young men, but also in other populations such as women, older adults, and individuals with muscle wasting diseases.
Tue A.H. Lassen, Lars Lindstrøm, Simon Lønbro, and Klavs Madsen
The present study investigated individualized sodium bicarbonate (NaHCO3−) supplementation in elite orienteers and its effects on alkalosis and performance in a simulated sprint orienteering competition. Twenty-one Danish male and female elite orienteers (age = 25.2 ± 3.6 years, height = 176.4 ± 10.9 cm, body mass = 66.6 ± 7.9 kg) were tested twice in order to identify individual time to peak blood bicarbonate (HCO3− peak) following supplementation of 0.3 g/kg body mass NaHCO3 with and without warm-up. The athletes also performed two 3.5 km time-trial runs (TT-runs) following individualized timing of NaHCO3 supplementation (SBS) or placebo (PLA) on separate days in a randomized, double-blind, cross-over design. The occurrence of individual peak HCO3− and pH ranged from 60 to 180 min. Mean HCO3− and pH in SBS were significantly higher compared with PLA 10 min before and following the TT-run (p < .01). SBS improved overall performance in the 3.5 km TT-run by 6 s compared with PLA (775.5 ± 16.2 s vs. 781.4 ± 16.1 s, respectively; p < .05). SBS improved performance in the last half of the TT-run compared with PLA (p < .01). In conclusion, supplementation with NaHCO3 followed by warm-up resulted in individualized alkalosis peaks ranging from 60 to 180 min. Individualized timing of SBS in elite orienteers induced significant alkalosis before and after a 3.5 km TT and improved overall performance time by 6 s, which occurred in the last half of the time trial. The present data show that the anaerobic buffer system is important for performance in these types of endurance events lasting 12–15 min.