Eat to compete: evidence-based perspectives for health and performance

During the past decade or so, nutrition arguably becomes the critical factor behind sport success, with many top-level athletes and “weekend warriors” recognize and practice specific dietary interventions like never before! Mass media and social networks are heavily loaded with “revolutionary” nutritional plans and performance-enhancing agents; however, many popular beliefs and myths often muddle picture on effective and safe dietary programs for exercising humans. This trend was accompanied by an outbreak of sport nutrition as an academic discipline. Hundreds of scientific papers appear every month, dealing with many basic and applied topics on sport nutrition and exercise metabolism, sometimes with rather conflicting conclusions. However, through developing new approaches and using state-of-the art technology, including omics, precision medicine, or CRISPR gene editing, sport nutrition community of today continues to better understand and address nutritional needs of active populations of all ages.

In aim to promote comprehensive evidence-based approach to sport nutrition (and debunk few myths), Research in Sports Medicine launched this special issue, covering a wide range of topics related to the discipline – from fundamental science that addresses subcellular and molecular issues in exercise metabolism and nutrition, to practical dietary approaches that target specific sport disciplines. Most articles to this issue are review articles (8 out of 9), and the remaining one is a research paper. The articles are contributed by the authors from Australia, Canada, Italy, Spain, South Africa, Iran, United Kingdom and the United States.

The opening article for this Special Issue deals with metabolic adaptations to endurance exercise (Earnest, Rothschild, Harnish, & Naderi, 2018). Dr. Conrad Earnest from Texas A&M University with his co-workers overview nutritional practices (such as fasted training or carbohydrate manipulation) and ergogenic aids (including caffeine and nitrates) frequently manipulated by elite and sub-elite endurance athletes. Besides training alterations, endurance performance appears to have a strong potential to be affected by periodized nutrition regimen, primarily through carbohydrate manipulation during training.

The hormesis theory has been well recognized as a fundamental concept in sports medicine and nutrition. How to achieve favorable balance between exercise-induced oxidative stress and antioxidant defense has been discussed in the second article in this issue. Dr. Daniela Caporossi and her group from the University of Rome consider the pros and cons of antioxidant supplementation in sport, highlighting possible advantages and disadvantages for using individual or combined antioxidants in the athletic environment (Antonioni, Fantini, Dimauro, & Caporossi, 2018).

The group of Dr. Martin D. Hoffman from the University of California Davis explores highly relevant topics on ultra-endurance nutrition in two separate review articles. In the first paper, the authors discuss several nutritional challenges seen during ultra-endurance activities, including energy depletion and gastrointestinal perturbations, and have suggested few dietary strategies that might provide efficacious nutritional support in athletes participating in ultra-endurance sports (Costa, Hoffman, & Stellingwerff, 2018). Second article focuses to hydration in ultra-endurance activities (Hoffman, Stellingwerff, & Costa, 2018). Here, the authors present the prevalence of inappropriate hydration during endurance and ultra-endurance competitions, and discuss the mean of proper hydration in these demanding events. Both papers provide many practical recommendations that might be highly applicable as a nutritional advice during prolonged exercise.

The fifth paper is entitled “High-protein diets in trained individuals” (Antonio, 2018). In this review article, Dr. Jose Antonio from Nova Southeastern University examines the current literature on high protein intakes in sedentary and trained individuals, and provide a rationale for protein consumption ≥ 2.2 g/kg/day in exercise-trained individuals for improved body composition, performance and health. Dr. Antonio also highlights the inappropriate use of percentages to define high protein intakes among athletes, which might be misleading as a way to define macronutrient intakes.

The supplementation with β-hydroxy-β-methyl butyrate (HMB) is an area of increasing interest in sport and exercise nutrition. HMB has been widely used as a performance-enhancing agent, usually combined with exercise training, to improve muscular performance and enhance recovery. Dr. Jay R. Hoffman and his group from the University of Central Florida critically overview HMB kinetics, dosing, and efficacy and safety of HMB supplementation in untrained and recreationally trained Individuals, and competitive athletes in limiting muscle degradation and increasing muscle protein synthesis (Gepner, Varanoske, Boffey, & Hoffman, 2018).

Omega-3 polyunsaturated fatty acids (PUFAs) are well-known as strong anti-inflammatory compounds, yet do supplemental PUFAs possess any ergogenic properties is open to discussion. To answer this, Dr. Stuart D.R. Galloway and co-authors from the University of Stirling analyzed the scientific literature examining the efficacy of PUFA supplementation to improve athletic performance (Philpott, Witard, & Galloway, 2018). Specifically, PUFA efficacy has been evaluated in both power-based and endurance-based athletes, but also for team-sport performance in the context of promoting muscle adaptation, energy metabolism, muscle recovery and injury prevention.

In the eight article, Dr. Juan Del Coso and his colleagues from the Camilo José Cela University conducted a systematic review and meta-analysis to determine the efficacy of acute caffeine ingestion on exercise performance in team sports (Salinero, Lara, & Del Coso, 2018). After the evaluation of 34 experiments included in this meta-analysis, with total sample consisted of over 400 athletes from various team sports, the authors reported beneficial effects of pre-exercise ingestion of a moderate dose of caffeine (e.g. 3 mg/kg) in increasing several physical performance variables. However, it seems that the use of caffeine should only be focused to high-performing athletes, after an evaluation of caffeine-related draw-backs and possible adverse events.

The special issue ends with a research paper evaluating factors that influences food choices in endurance athletes (Blennerhassett, McNaughton, & Sparks, 2018). The group lead by Dr. Lars McNaughton from Edge Hill University assessed the importance of different factors that influence the food choices of this specific population, using a valid and reliable tool. It appears that using U-FCQ questionnaire provides a reliable instrument to evaluate food choices of ultra-endurance athletes during periods of high-volume training and competition, and perhaps tailor nutritional recommendations accordingly.

We hope that many professionals working in the field of sport and exercise nutrition, from nutritionists and physicians, to strength and conditioning experts, will find this journal issue useful in identifying optimal nutritional strategies to address dietary requirements, and safely and effectively improve nutrition, health and performance of athletes they are caring for.