Sports nutrition is a constantly evolving field with hundreds of research papers published annually. In the year 2017 alone, 2082 articles were published under the key words 'sport nutrition'. ...Consequently, staying current with the relevant literature is often difficult.
This paper is an ongoing update of the sports nutrition review article originally published as the lead paper to launch the Journal of the International Society of Sports Nutrition in 2004 and updated in 2010. It presents a well-referenced overview of the current state of the science related to optimization of training and performance enhancement through exercise training and nutrition. Notably, due to the accelerated pace and size at which the literature base in this research area grows, the topics discussed will focus on muscle hypertrophy and performance enhancement. As such, this paper provides an overview of: 1.) How ergogenic aids and dietary supplements are defined in terms of governmental regulation and oversight; 2.) How dietary supplements are legally regulated in the United States; 3.) How to evaluate the scientific merit of nutritional supplements; 4.) General nutritional strategies to optimize performance and enhance recovery; and, 5.) An overview of our current understanding of nutritional approaches to augment skeletal muscle hypertrophy and the potential ergogenic value of various dietary and supplemental approaches.
This updated review is to provide ISSN members and individuals interested in sports nutrition with information that can be implemented in educational, research or practical settings and serve as a foundational basis for determining the efficacy and safety of many common sport nutrition products and their ingredients.
Purpose of Review
During a soccer season, athletes tend to play intense and light matches such as decisive and qualifying games. The amount of muscle glycogen stores is a determining factor of ...performance during exercise, and manipulation of carbohydrate intake during the soccer season to enhance muscle glycogen stores can improve the performance of elite soccer players. The purpose of this review is to provide a holistic view of the periodization of carbohydrates and their effects on sports performance, based on what the literature recommends for the periodization of carbohydrates for endurance athletes, and of muscle glycogen recovery and compensation among professional soccer players.
Recent Findings
The ingestion of large amounts of carbohydrates (CHO;10 g/kg of body weight (BW)/day) is important 36 h before a match for the elite soccer player to ensure muscle glycogen supercompensation. In addition, elite soccer players should intake 1 to 1.5 g/kg BW/h within the first 4 h after a soccer game to maximize glycogen resynthesis. However, the season is comprised of away and home games that require different intensities; thus, soccer players need to periodize CHO intake based on evidence-based recommendations such as “train low,” “train low, compete high,” and/or “sleep low.” The goal is to induce training adaptations by alternating with high or low CHO availability based on seasons, matches, and training intensities. The strategy can result in improved performance during games.
Summary
Periodizing the consumption of carbohydrates, based on the intensity of training and matches, should include more carbohydrates when the matches require higher intensity and fewer carbohydrates when they require lower intensity; this is a strategy that will improve the performance of elite soccer athletes.
Position statement: The International Society of Sports Nutrition (ISSN) provides an objective and critical review of the mechanisms and use of probiotic supplementation to optimize the health, ...performance, and recovery of athletes. Based on the current available literature, the conclusions of the ISSN are as follows: 1)Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host (FAO/WHO).2)Probiotic administration has been linked to a multitude of health benefits, with gut and immune health being the most researched applications.3)Despite the existence of shared, core mechanisms for probiotic function, health benefits of probiotics are strain- and dose-dependent.4)Athletes have varying gut microbiota compositions that appear to reflect the activity level of the host in comparison to sedentary people, with the differences linked primarily to the volume of exercise and amount of protein consumption. Whether differences in gut microbiota composition affect probiotic efficacy is unknown.5)The main function of the gut is to digest food and absorb nutrients. In athletic populations, certain probiotics strains can increase absorption of key nutrients such as amino acids from protein, and affect the pharmacology and physiological properties of multiple food components.6)Immune depression in athletes worsens with excessive training load, psychological stress, disturbed sleep, and environmental extremes, all of which can contribute to an increased risk of respiratory tract infections. In certain situations, including exposure to crowds, foreign travel and poor hygiene at home, and training or competition venues, athletes' exposure to pathogens may be elevated leading to increased rates of infections. Approximately 70% of the immune system is located in the gut and probiotic supplementation has been shown to promote a healthy immune response. In an athletic population, specific probiotic strains can reduce the number of episodes, severity and duration of upper respiratory tract infections.7)Intense, prolonged exercise, especially in the heat, has been shown to increase gut permeability which potentially can result in systemic toxemia. Specific probiotic strains can improve the integrity of the gut-barrier function in athletes.8)Administration of selected anti-inflammatory probiotic strains have been linked to improved recovery from muscle-damaging exercise.9)The minimal effective dose and method of administration (potency per serving, single vs. split dose, delivery form) of a specific probiotic strain depends on validation studies for this particular strain. Products that contain probiotics must include the genus, species, and strain of each live microorganism on its label as well as the total estimated quantity of each probiotic strain at the end of the product's shelf life, as measured by colony forming units (CFU) or live cells.10)Preclinical and early human research has shown potential probiotic benefits relevant to an athletic population that include improved body composition and lean body mass, normalizing age-related declines in testosterone levels, reductions in cortisol levels indicating improved responses to a physical or mental stressor, reduction of exercise-induced lactate, and increased neurotransmitter synthesis, cognition and mood. However, these potential benefits require validation in more rigorous human studies and in an athletic population.
Glutamine (GLN) and glutamic acid (GLA) are involved in many metabolic processes, from nucleotide synthesis to nerve impulse conduction; GLN is also an energy substrate for immunocompetent cells, ...making it an important link in the immune response. In stressful situations, which include significant physical activity, plasma levels of GLN and GLA decrease as a result of the amino acid being actively consumed in many biochemical reactions. GLN deficiency can lead to a number of negative manifestations in athletes and adversely affect athletic performance. The purpose of this work was to study the effects of glutamine deficiency and the possible replenishment of the deficiency by the consumption of exogenous forms of the substance when using glutamine-containing products; special attention was paid to the study of transient decrease in immune function as a relevant factor that impairs the mode of sports training.
The nitrates found in beetroot juice (BR) are known to be a precursor of nitric oxide (NO). NO is a known vasodilator which allows more oxygen to travel in the blood and may improve muscle ...efficiency. This study aims to measure the effect of BR supplementation on performance on 500-meter row time for trained CrossFit athletes. Many past studies have analyzed the effect of BR on male athletes, this study aimed to include both males and females.
This study used a randomized, cross-over, double-blind, placebo-controlled design to measure 500-meter row time. Thirty athletes age 18–60 consumed either a 2.7 oz shot of BR (6.5 mmol nitrate) or a placebo nitrate-free beetroot juice (PL). Two hours later, they rowed 500 meters. After at least a seven-day washout period, athletes repeated the 500-meter row with either BR or PL for comparison. This study was performed from July 2019 – January 2020 and was conducted in Mercer Island, Washington.
Ten males age 18.0 to 60.3 (median 47.7) and twenty females age 26.7 to 58.3 (median 43.8), participated in this study. Row times for the 500-meter row ranged from 88.2 seconds to 150.7 seconds. Data indicate that although 60% of all participants rowed faster with BR (mean 112.83 seconds), compared to PL (mean 113.40 seconds), the difference in the means of row times (–0.563) was not significant overall (P = 0.29). However, for the 10 males, row times were significantly faster (1.02 second difference, P = 0.04) on average with BR compared to PL. For the 20 females, the difference in mean row time (–0.335 seconds) was not significant (P = 0.66). Competitive rowers were defined as those who rowed under 110 seconds (N = 15). For competitive rowers (10 males, 5 females), row times were significantly faster with BR compared to PL (difference in means –0.94, P = 0.009). However, for those rowers, the P-value of drink * group was 0.015.
Dietary nitrate improved indoor rowing performance in males but not in females. In addition, competitive rowers were also significantly faster with BR, however, there may be an order bias, since there was significant interaction between beverage type and testing order. Food based nitrate supplements may increase rowing performance with male rowers.
Supported by Bastyr Faculty Student Research Grant.
Nutrition is a key element in post-exercise regeneration. Various studies suggest that ingestion of combined carbohydrates and proteins after exercise result in a decrease of inflammatory processes ...and consequently in an increase of regeneration and physical performance. Recent studies compared the pro-regenerative effects of protein/carbohydrate shakes with the intake of foodstuffs (white bread and high protein cheese) on the skeletal muscle after acute endurance exercise.
The aim of this study was to evaluate the influence of a conventional curd/juice shake on the regenerative capacity of soccer players after intensive strength training.
Therefore, sixteen young healthy in-season football payers run through a placebo checked double-blind crossover study with two groups. After a standardized training protocol, 3 sets of 12 reps deep back squats and 3 sets of 15 reps drop jumps, the participants ingested either a placebo shake (placebo-group, total calories < 10 kcal) or a conventional shake of 300 g curd and 200 ml grape juice (protein 35.8 g, carbohydrates 43.6 g, fat 0.9 g, total calories 338 kcal). To evaluate the muscle damage effects, serum creatin kinase (CK) as a physiological parameter as well 10 m sprint, counter movement jump (CMJ) and 3RM-squat as functional markers were measured at two time points (t0, t24). In addition, the CK of five players was analysed after a soccer match.
The results show a positive trend concerning sprint and squat performance in the shake group. Especially in the squat group a significant decrease of performance was observed in the placebo group compared to the shake group (PL: –5.0 kg, P ≤ 05, SH: –3,2 kg, P = .10). In CMJ and CK no difference was observed between the two groups. In both groups, the jump in CMJ decreased and the CK value increased significantly. The increase in CK due to intensive resistance training is also comparable to the muscle damage after a football match.
In summary, it was found that a quark/juice shake has a positive influence on strength performance in soccer players after intensive strength training. These findings confirm observations from previous studies. However, the positive effects on CK could not be observed in this study. Therefore, further research on conventional foodstuff after resistance training is necessary.
No funding.
Water loss via sweating increases during exercise especially in the heat, however, the evidence is limited as to whether moderate physical activity (PA) and ambient temperature (Ta) influence water ...intake in daily life. The purpose of this study was to examine the influence of PA and Ta on water intake and hydration state in free-living individuals.
Ninety-five healthy, but non-athletic (< 4 h of exercise per week), adults (52 females) participated in the study. PA was assessed via the International Physical Activity Questionnaire and scored/stratified into PAhigh, PAmoderate, and PAlow. Fluid consumption was assessed by a validated 7-day fluid diary and was used to assess water intake from liquids (WI-L), plain water intake (PWI) and water intake from other beverages (WI-B). Food consumption was also recorded for 7 days and analyzed with the Nutrition Data System for Research (NDSR) software and was used to calculate water from foods (WI-F). All sources of water were pooled to calculate total water intake (TWI). Hydration was assessed with blood and a 24-h urine sample.
People with PAhigh had higher TWI (4.0 ± 1.4 L·d–1 vs. 2.8 ± 0.7 L·d–1; P = 0.010) and WI-L (3.2 ± 1.4 L·d–1 vs. 2.1 ± 0.5 L·d–1; P = 0.009), compared to PAlow. PWI was also higher in PAhigh group (2.20 ± 1.20 L·d-1) compared to PAlow (1.10 ± 0.72 L·d–1, P = 0.003), but there was no significant difference in WI-B and WI-F (P ≥ 0.05). PWI showed a significant association with Ta (R2 = 0.08; P = 0.008), while WI-B did not (P ≥ 0.05). Positive associations between PWI and Ta only remained in the PAhigh group when stratified by different PA levels (R2 = 0.40; P = 0.028). However, the hydration state was not affected by PA nor Ta (P ≥ 0.05).
Higher PA and Ta were associated with higher TWI, and this appeared to be driven by PWI, and not by other beverages nor water from food. Hydration state was similar across levels of PA, likely because of the higher TWI in the PAhigh group.
This study was funded by Danone Research.
With the rise in physical inactivity and its related diseases, it is necessary to understand the mechanisms involved in physical activity regulation. Scientists have explored physical activity ...regulation by investigating various physiological mechanisms involving hormones, neurotransmitters, and genetics; however, little is known about the role of metabolism on physical activity level. We hypothesize that protein turnover in specific organs like the muscle is higher in mice previously exhibiting high physical activity levels, as a mechanism to adapt to the increased demand. Therefore, we studied protein fractional synthesis rate (FSR) in tissues of inherently high and low active mice.
In order to study protein FSR of various organs, we assessed 12-week-old male inherently low-active (LA) mice (n = 23, lean body mass: 21.0 ± 1.1 g, C3H/HeJ strain) and high active (HA) mice (n = 20, lean body mass: 22.5 ± 1.3, C57L/J strain). One day before tissue collection, a D2O bolus was administered via intraperitoneal injection, and mice were provided D2O enriched drinking water to enrich the total body water to about 5% D2O. Eleven tissues (kidney, heart, lung, muscle, fat, jejunum, ileum, liver, brain, skin, and bone) were collected and analyzed for enrichment of alanine in the intracellular and protein-bound pool (LC-MS/MS). FSR was calculated as -ln(1-enrichment) as fraction per day. Data are mean ± SE (unpaired t-test: GraphPad Prism 8.2).
We did not find significant differences between protein FSR of HA and LA mice in any measured organ. Example: Protein FSR (fraction/day): muscle (LA: 0.0326±-0.0026, HA: 0.0331 ± 0.0018, P = 0.8673), liver (0.3568 ± 0.0219, 0.3499 ± 0.0217, P = 0.8263), brain (0.0981 ± 0.0056, 0.1041 ± 0.0063, P = 0.4758).
The observed lack of significant differences in high and low-active mice suggests that differences in specific organ tissue protein turnover may not be a mechanism regulating inherent physical activity level. Since protein turnover is representative of the ability to adapt through upregulation and downregulation of metabolic processes, these results show that high-active mice are inherently no more equipped for metabolic regulation than the low active mice.
Sydney and J.L. Huffines Institute for Sports Medicine, Human Performance Student Research Grant and CTRAL Grant.
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