José Miguel Martínez Sanz

Necesidades proteicas de los deportistas y pautas diétetico-nutricionales para la ganancia de masa muscular

One of the most important effects of strength training is muscular hypertrophy. Athletes should optimize their nutritional management in order to compensate their own genetic limitations. The aim of this review is to analyze the scientific evidence concerning protein intake as a tool to achieve muscle hypertrophy. Depending on the expenditure and energy intake of athlete, a daily protein ranging between 10-15% of total dietary intake is needed. However in sports diets, it is preferable to estimate the amount of protein needed per kilogram of body weight in each individual. In this regard athletes should ingest an amount between 1.2 g and 1.8 g of proteins/kg of body mass/day to maintain their lean mass. In order to increase muscle mass (0.5 kg/week), athletes should take between 1.6 g and 1.8 g of protein/kg/day with an increase of 400-500 kcal in their daily diet. These needs will depend on the sport, muscular catabolic status, the athlete’s lean mass and glycogen stores. Protein needs will increase if muscle and liver glycogen stores are empty. Excess of protein intake (more than 2 g/kg/day), with full glycogen stores, does not benefit the athlete and could cause an increase in circulating ketones and urea, thereby producing an early dehydration.

Intended or Unintended Doping? A Review of the Presence of Doping Substances in Dietary Supplements Used in Sports

Introduction: The use of dietary supplements is increasing among athletes, year after year. Related to the high rates of use, unintentional doping occurs. Unintentional doping refers to positive anti-doping tests due to the use of any supplement containing unlisted substances banned by anti-doping regulations and organizations, such as the World Anti-Doping Agency (WADA). The objective of this review is to summarize the presence of unlabeled doping substances in dietary supplements that are used in sports. Methodology: A review of substances/metabolites/markers banned by WADA in ergonutritional supplements was completed using PubMed. The inclusion criteria were studies published up until September 2017, which analyzed the content of substances, metabolites and markers banned by WADA. Results: 446 studies were identified, 23 of which fulfilled all the inclusion criteria. In most of the studies, the purpose was to identify doping substances in dietary supplements. Discussion: Substances prohibited by WADA were found in most of the supplements analyzed in this review. Some of them were prohormones and/or stimulants. With rates of contamination between 12 and 58%, non-intentional doping is a point to take into account before establishing a supplementation program. Athletes and coaches must be aware of the problems related to the use of any contaminated supplement and should pay special attention before choosing a supplement, informing themselves fully and confirming the guarantees offered by the supplement.

Branched Chain Amino Acids and Sports Nutrition and Energy Homeostasis

Abstract The branched chain amino acids leucine, isoleucine, and valine cannot be synthesized by the human body and therefore must be provided in the diet. These amino acids are metabolized primarily in skeletal muscle, which means that they are released into the liver and their ingestion causes a rapid increase in plasma levels. There are different studies and scientific opinions regarding the benefit of these amino acids in sports performance and different sports. Some attributes described are the stimulation of muscle protein synthesis, the prevention of muscle protein breakdown and a reduction in the markers of exercise-induced muscle damage, and a reduction in feelings of fatigue. Despite these attributes, the investigations are not entirely conclusive. This chapter reviews the effects of branched chain amino acids and their practical applications in sports.