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Manipulation of Dietary Intake on Changes in Circulating Testosterone Concentrations.
Zamir, A, Ben-Zeev, T, Hoffman, JR
Nutrients. 2021;13(10)
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Androgens, like testosterone, are steroid hormones commonly associated with reproduction. However, they also govern metabolic functions, body composition and growth. Higher levels of circulating androgens enhance athletic performance by supporting metabolic activities such as protein production, regeneration and growth and by inhibiting breakdown processes. Manipulating testosterone to enhance athletic performance without the use of anabolic steroids hormones has been of much interest. As macro-and micronutrients can influence androgen hormones, this review examined whether specific energy and nutrient intake can ‘naturally’ manipulate testosterone levels. The authors describe the metabolic functions of testosterone before exploring the current evidence on selected plant extracts and nutrients and their impact on aromatase activity. Inhibiting aromatase can prevent androgens from being converted into oestrogen and thus may help to raise circulating androgens. Discussed are a range of plant-derived compounds, flavonoids, macronutrients and micronutrients (Vitamin D, Zinc and Magnesium) and their impact on testosterone levels. The authors conclude that the nutrients discussed have some supportive evidence, yet overall findings are inconclusive due to limited studies. Regarding macronutrients more research is available, and the evidence supports that low energy intake negatively impacts testosterone levels and performance. Whereby supplementation of vitamins crucial to testosterone production seems to provide value in cases of deficiency further research is required. This article yields an overview of plant compounds, macro-and micronutrients and their potential impact on circulating testosterone levels. While low energy intake and nutrient deficiencies appears to be unfavourable, the absence of clear evidence on other compounds would warrant further case-specific investigations.
Abstract
Elevations in the circulating concentration of androgens are thought to have a positive effect on the anabolic processes leading to improved athletic performance. Anabolic-androgenic steroids have often been used by competitive athletes to augment this effect. Although there has been concerted effort on examining how manipulating training variables (e.g., intensity and volume of training) can influence the androgen response to exercise, there has been much less effort directed at understanding how changes in both macronutrient and micronutrient intake can impact the androgen response. Thus, the focus of this review is to examine the effect that manipulating energy and nutrient intake has on circulating concentrations of testosterone and what the potential mechanism is governing these changes.
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Development of Maximal Dynamic Strength During Concurrent Resistance and Endurance Training in Untrained, Moderately Trained, and Trained Individuals: A Systematic Review and Meta-analysis.
Petré, H, Hemmingsson, E, Rosdahl, H, Psilander, N
Sports medicine (Auckland, N.Z.). 2021;51(5):991-1010
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Athletes often require a combination of both strength and endurance in their chosen sport. As a result, a training programme which has both endurance and strength exercises within the same training period has become popular and is known as concurrent training. However, there are conflicting studies on the effectiveness of this way of training for athletic performance. This systematic review of 27 studies aimed to determine the overall effect of concurrent training on athletic performance based on the results of several studies and whether the time between training types could influence the effect. The results showed that leg press and squat exercises were negatively affected in trained individuals, but only if they were performed within the same training session. This was not evident in untrained and moderately trained individuals. It was concluded that in trained athletes, the performance of endurance and strength training within the same session can have a detrimental effect on lower body strength development. This study could be used by professionals to recommend that trained individuals separate endurance and strength training when increased strength is the goal.
Abstract
BACKGROUND The effect of concurrent training on the development of maximal strength is unclear, especially in individuals with different training statuses. OBJECTIVE The aim of this systematic review and meta-analysis study was to compare the effect of concurrent resistance and endurance training with that of resistance training only on the development of maximal dynamic strength in untrained, moderately trained, and trained individuals. METHODS On the basis of the predetermined criteria, 27 studies that compared effects between concurrent and resistance training only on lower-body 1-repetition maximum (1RM) strength were included. The effect size (ES), calculated as the standardised difference in mean, was extracted from each study, pooled, and analysed with a random-effects model. RESULTS The 1RM for leg press and squat exercises was negatively affected by concurrent training in trained individuals (ES = - 0.35, p < 0.01), but not in moderately trained ( - 0.20, p = 0.08) or untrained individuals (ES = 0.03, p = 0.87) as compared to resistance training only. A subgroup analysis revealed that the negative effect observed in trained individuals occurred only when resistance and endurance training were conducted within the same training session (ES same session = - 0.66, p < 0.01 vs. ES different sessions = - 0.10, p = 0.55). CONCLUSION This study demonstrated the novel and quantifiable effects of training status on lower-body strength development and shows that the addition of endurance training to a resistance training programme may have a negative impact on lower-body strength development in trained, but not in moderately trained or untrained individuals. This impairment seems to be more pronounced when training is performed within the same session than in different sessions. Trained individuals should therefore consider separating endurance from resistance training during periods where the development of dynamic maximal strength is prioritised.
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Acute effect of high-definition and conventional tDCS on exercise performance and psychophysiological responses in endurance athletes: a randomized controlled trial.
da Silva Machado, DG, Bikson, M, Datta, A, Caparelli-Dáquer, E, Unal, G, Baptista, AF, Cyrino, ES, Li, LM, Morya, E, Moreira, A, et al
Scientific reports. 2021;11(1):13911
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Exercise-induced fatigue can be associated with a limited descending command from the central nervous system to the muscle which may affect muscle contraction and its ability to generate force. Transcranial direct current stimulation (tDCS) is the application of weak electrical current to stimulate different areas of the brain to influence exercise performance and perception. High-definition transcranial direct current stimulation (HD-tDCS) is a modification of conventional tDCS to increase the focality, precision, long-lasting effects and greater neuronal excitability change. This single-centre, randomised, crossover, single-blinded, sham-controlled trial compared the effects of HD-tDCS and conventional tDCS on exercise performance and psychophysiological responses in healthy young male endurance athletes. The study found no effect of HD-tDCS or conventional tDCS on exercise performance and psychophysiological responses to exhaustive exercise. Further robust studies are required to evaluate the effects of both forms of tDCS in athletes compared to non-athletes and its effects when tDCS is applied to other areas of the central nervous system. Healthcare professionals can use the results of this study to understand that there is no evidence currently to support the utilisation of tDCS in improving exercise performance in athletes.
Abstract
Transcranial direct current stimulation (tDCS) has been used aiming to boost exercise performance and inconsistent findings have been reported. One possible explanation is related to the limitations of the so-called "conventional" tDCS, which uses large rectangular electrodes, resulting in a diffuse electric field. A new tDCS technique called high-definition tDCS (HD-tDCS) has been recently developed. HD-tDCS uses small ring electrodes and produces improved focality and greater magnitude of its aftereffects. This study tested whether HD-tDCS would improve exercise performance to a greater extent than conventional tDCS. Twelve endurance athletes (29.4 ± 7.3 years; 60.15 ± 5.09 ml kg-1 min-1) were enrolled in this single-center, randomized, crossover, and sham-controlled trial. To test reliability, participants performed two time to exhaustion (TTE) tests (control conditions) on a cycle simulator with 80% of peak power until volitional exhaustion. Next, they randomly received HD-tDCS (2.4 mA), conventional (2.0 mA), or active sham tDCS (2.0 mA) over the motor cortex for 20-min before performing the TTE test. TTE, heart rate (HR), associative thoughts, peripheral (lower limbs), and whole-body ratings of perceived exertion (RPE) were recorded every minute. Outcome measures were reliable. There was no difference in TTE between HD-tDCS (853.1 ± 288.6 s), simulated conventional (827.8 ± 278.7 s), sham (794.3 ± 271.2 s), or control conditions (TTE1 = 751.1 ± 261.6 s or TTE2 = 770.8 ± 250.6 s) [F(1.95; 21.4) = 1.537; P = 0.24; η2p = 0.123]. There was no effect on peripheral or whole-body RPE and associative thoughts (P > 0.05). No serious adverse effect was reported. A single session of neither HD-tDCS nor conventional tDCS changed exercise performance and psychophysiological responses in athletes, suggesting that a ceiling effect may exist.
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Relationship between energy availability, energy conservation and cognitive restraint with performance measures in male endurance athletes.
Jurov, I, Keay, N, Hadžić, V, Spudić, D, Rauter, S
Journal of the International Society of Sports Nutrition. 2021;18(1):24
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Athletes who do endurance exercise sometimes experience low energy availability which can affect their performance. Low energy availability may lead to a syndrome called Relative energy deficiency in sports. This cross-sectional controlled study assessed the pre-race energy availability in twelve lean, healthy endurance athletes without pre-existing signs of relative energy deficiency. Results showed that two-thirds of the participants had low mean energy availability. Lower energy availability was associated with higher energy expenditure. Participants in the study deliberately restricted their energy intake to achieve an optimal body composition. This may have led to energy conservation in participants. However, the study failed to show any associations between energy conservation and energy availability. There is a need for more robust studies to determine the true cut-off value of energy availability in male endurance athletes. Healthcare professionals can use the results of this study to understand the need for eating behaviour screening to reduce disordered eating in endurance athletes and the clinical applicability of energy conservation assessment.
Abstract
BACKGROUND Low energy availability in male athletes has gained a lot of attention in recent years, but direct evidence of its effects on health and performance is lacking. The aim of this research was to objectively measure energy availability (EA) in healthy male endurance athletes without pre-existing relative energy deficiency signs during pre-race season. METHODS Twelve trained endurance athletes (performance level 3, 4, and 5) participated in the cross-sectional controlled laboratory study. Fat-free mass, exercise energy expenditure, and energy intake were measured to calculate EA. Resting energy expenditure was measured and estimated to assess energy conservation. Three specific performance tests were used to assess endurance, agility, and explosive strength performance. For psychological evaluation, the Three Factor Eating Questionnaire and a short Well-being questionnaire were completed. RESULTS Mean EA was 29.5 kcal/kg FFM/day. The majority (66.6%) had EA under the threshold for low EA in females. Critical cognitive restraint (≥13) was reported by 75% of participants. There were no differences in performance, blood values, or psychological evaluation when subjects were divided into two groups divided by EA = 30 kcal/kg FFM/day. Cognitive restraint was negatively associated with measured resting energy expenditure and energy conservation (r = -.578, p = .025 and r = -.549, p = .032, respectively). CONCLUSIONS The mean EA measured in this study supports the theory that the threshold for low EA in endurance male athletes might be under the threshold for females. In addition, we confirmed cognitive restraint could be useful for early detection of energy conservation. The high cognitive restraint as measured in our sample stressed the need of eating behavior screening in endurance athletes in order to reduce risk of any disordered eating patterns.
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The Effects of Exercise on Indirect Markers of Gut Damage and Permeability: A Systematic Review and Meta-analysis.
Chantler, S, Griffiths, A, Matu, J, Davison, G, Jones, B, Deighton, K
Sports medicine (Auckland, N.Z.). 2021;51(1):113-124
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Gut permeability and intestinal cell damage are often observed in various gastrointestinal and metabolic conditions. Based on recent findings, exercise appears to cause damage to intestinal cells, leading to an increase in gut permeability. The aim of this review was to determine the effect of an acute bout of exercise on gut damage and permeability and explore the plausible mechanisms underlying these effects. This review analysed 34 studies that evaluated biomarkers of gut permeability and cell damage in response to exercise compared to resting controls. These findings revealed a significant impact of exercise on gut damage and permeability, and the markers were exacerbated when exercise was performed in hot conditions. The duration of exercise did not have any impact on cell damage or permeability. Based on these results, the authors conclude a single bout of exercise increases gut damage and permeability and they encourage further investigation into nutritional strategies to prevent adverse effects during the post-exercise period. Future research should consider the efficacy nutritional interventions to minimize these negative effects to optimise athletic health and performance.
Abstract
AIM: Exercise appears to cause damage to the endothelial lining of the human gastrointestinal tract and elicit a significant increase in gut permeability. OBJECTIVE The aim of this review was to determine the effect of an acute bout of exercise on gut damage and permeability outcomes in healthy populations using a meta-analysis. METHODS PubMed, The Cochrane Library as well as MEDLINE, SPORTDiscus and CINHAL, via EBSCOhost were searched through February 2019. Studies were selected that evaluated urinary (ratio of disaccharide/monosaccharide excretion) or plasma markers [intestinal Fatty Acid Binding Protein (i-FABP)] of gut permeability and gut cell damage in response to a single bout of exercise. RESULTS A total of 34 studies were included. A random-effects meta-analysis was performed, and showed a large and moderate effect size for markers of gut damage (i-FABP) (ES 0.81; 95% CI 0.63-0.98; n = 26; p < 0.001) and gut permeability (Disaccharide Sugar/Monosaccharide Sugar) (ES 0.70; 95% CI 0.29-1.11; n = 17; p < 0.001), respectively. Exercise performed in hot conditions (> 23 °C) further increased markers of gut damage compared with thermoneutral conditions [ES 1.06 (95% CI 0.88-1.23) vs. 0.66 (95% CI 0.43-0.89); p < 0.001]. Exercise duration did not have any significant effect on gut damage or permeability outcomes. CONCLUSIONS These findings demonstrate that a single bout of exercise increases gut damage and gut permeability in healthy participants, with gut damage being exacerbated in hot environments. Further investigation into nutritional strategies to minimise gut damage and permeability after exercise is required. PROSPERO database number (CRD42018086339).
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Time-restricted eating effects on performance, immune function, and body composition in elite cyclists: a randomized controlled trial.
Moro, T, Tinsley, G, Longo, G, Grigoletto, D, Bianco, A, Ferraris, C, Guglielmetti, M, Veneto, A, Tagliabue, A, Marcolin, G, et al
Journal of the International Society of Sports Nutrition. 2020;17(1):65
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Adequate nutrition is important for elite athletes, as nutrient availability influences energy expenditure, body composition, performance and exercise-induced immune responses. Time-restricted eating (TRE) is a form of intermittent fasting that has received much interest in recent years. Previous research of TRE suggested beneficial effects on performance in untrained individuals, by allowing weight loss whilst maintaining muscle functions. These qualities are of interest for endurance cyclists hence the authors of this study sought to investigate the impact of TRE in elite cyclists. Sixteen under-23 year old, elite cyclists were randomly assigned to eat within a TRE window of 8-hr or 15hr window during a 4-week, high-level endurance training phase. Both groups consumed their full estimated energy needs and markers such as fat and fat-free mass, VO2 max, basal metabolism, blood counts, anabolic hormones and inflammatory markers were measured. As a result, TRE produced weight loss, improved body composition and increased peak power output in relation to body weight without compromising aerobic performance. Furthermore, the TRE pattern proved helpful in mitigating some of the exercise-induced suppressions of the immune system. The authors concluded that TRE could be considered as part of a performance nutrition plan in endurance athletes. Particularly where there is a need to reduce body fat mass or for the management of training-induced depression of the immune system and associated respiratory infection susceptibility. This can be of clinical relevance in the support of endurance athletes.
Abstract
BACKGROUND Although there is substantial interest in intermittent fasting as a dietary approach in active individuals, information regarding its effects in elite endurance athletes is currently unavailable. The present parallel randomized trial investigated the effects of a particular intermittent fasting approach, called time-restricted eating (TRE), during 4 weeks of high-level endurance training. METHODS Sixteen elite under-23 cyclists were randomly assigned either to a TRE group or a control group (ND). The TRE group consumed 100% of its estimated daily energy needs in an 8-h time window (from 10:00 a.m. to 6:00 p.m.) whilst energy intake in the ND group was distributed in 3 meals consumed between 7:00 a.m. and 9:00 p.m. Fat and fat-free mass were estimated by bioelectrical impedance analysis and VO2max and basal metabolism by indirect gas analyzer. In addition, blood counts, anabolic hormones (i.e. free testosterone, IGF-1) and inflammatory markers (i.e. IL-6, TNF-α) were assessed. RESULTS TRE reduced body weight (- 2%; p = 0.04) and fat mass percentage (- 1.1%; p = 0.01) with no change in fat-free mass. Performance tests showed no significant differences between groups, however the peak power output/body weight ratio (PPO/BW) improved in TRE group due to weight loss (p = 0.02). Free testosterone and IGF-1 decreased significantly (p = 0.01 and p = 0.03 respectively) in TRE group. Leucocyte count decreased in ND group (p = 0.02) whilst the neutrophils-to-lymphocytes ratio (NLR) decreased significantly (p = 0.03) in TRE group. CONCLUSIONS Our results suggest that a TRE program with an 8-h feeding window elicits weight loss, improves body composition and increases PPO/BW in elite cyclists. TRE could also be beneficial for reducing inflammation and may have a protective effect on some components of the immune system. Overall, TRE could be considered as a component of a periodized nutrition plan in endurance athletes. TRIAL REGISTRATION This trial was retrospectively registered at clinicaltrials.gov as NCT04320784 on 25 March 2020.
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Ketone ester supplementation blunts overreaching symptoms during endurance training overload.
Poffé, C, Ramaekers, M, Van Thienen, R, Hespel, P
The Journal of physiology. 2019;597(12):3009-3027
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Overload training is often used by endurance athletes to improve endurance performance. Overload training, however, can result in muscle protein breakdown, a catabolic state, and a decrease in muscle performance. Therefore, this randomised, double-blinded, placebo-controlled study examined the protective effects of ketone ester supplementation in reducing the detrimental effects of endurance training-induced overreaching. When compared to the control group, the subjects taking oral ketone ester supplements showed a 15% increase in sustained training load and power output and maintained energy balance. Supplementation with ketones ester inhibited the night-time increase in neurotransmitter noradrenaline and hormone adrenaline and maintained heart rate, suggesting a blunting of cardiovascular, sympathetic and hormonal symptoms caused by the endurance training overload. Growth differentiation factor 15 (GDF15) increased by training overload was negated by ketone ester intake. Further studies should be conducted to establish the long-term effects of ketone esters in training and recovery. These results can help healthcare professionals better understand how elevated blood ketones can enhance exercise performance and reduce the detrimental effects of exercise overload.
Abstract
KEY POINTS Overload training is required for sustained performance gain in athletes (functional overreaching). However, excess overload may result in a catabolic state which causes performance decrements for weeks (non-functional overreaching) up to months (overtraining). Blood ketone bodies can attenuate training- or fasting-induced catabolic events. Therefore, we investigated whether increasing blood ketone levels by oral ketone ester (KE) intake can protect against endurance training-induced overreaching. We show for the first time that KE intake following exercise markedly blunts the development of physiological symptoms indicating overreaching, and at the same time significantly enhances endurance exercise performance. We provide preliminary data to indicate that growth differentiation factor 15 (GDF15) may be a relevant hormonal marker to diagnose the development of overtraining. Collectively, our data indicate that ketone ester intake is a potent nutritional strategy to prevent the development of non-functional overreaching and to stimulate endurance exercise performance. ABSTRACT It is well known that elevated blood ketones attenuate net muscle protein breakdown, as well as negate catabolic events, during energy deficit. Therefore, we hypothesized that oral ketones can blunt endurance training-induced overreaching. Fit male subjects participated in two daily training sessions (3 weeks, 6 days/week) while receiving either a ketone ester (KE, n = 9) or a control drink (CON, n = 9) following each session. Sustainable training load in week 3 as well as power output in the final 30 min of a 2-h standardized endurance session were 15% higher in KE than in CON (both P < 0.05). KE inhibited the training-induced increase in nocturnal adrenaline (P < 0.01) and noradrenaline (P < 0.01) excretion, as well as blunted the decrease in resting (CON: -6 ± 2 bpm; KE: +2 ± 3 bpm, P < 0.05), submaximal (CON: -15 ± 3 bpm; KE: -7 ± 2 bpm, P < 0.05) and maximal (CON: -17 ± 2 bpm; KE: -10 ± 2 bpm, P < 0.01) heart rate. Energy balance during the training period spontaneously turned negative in CON (-2135 kJ/day), but not in KE (+198 kJ/day). The training consistently increased growth differentiation factor 15 (GDF15), but ∼2-fold more in CON than in KE (P < 0.05). In addition, delta GDF15 correlated with the training-induced drop in maximal heart rate (r = 0.60, P < 0.001) and decrease in osteocalcin (r = 0.61, P < 0.01). Other measurements such as blood ACTH, cortisol, IL-6, leptin, ghrelin and lymphocyte count, and muscle glycogen content did not differentiate KE from CON. In conclusion, KE during strenuous endurance training attenuates the development of overreaching. We also identify GDF15 as a possible marker of overtraining.
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Chocolate milk for recovery from exercise: a systematic review and meta-analysis of controlled clinical trials.
Amiri, M, Ghiasvand, R, Kaviani, M, Forbes, SC, Salehi-Abargouei, A
European journal of clinical nutrition. 2019;73(6):835-849
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Post-exercise nutrition is highly important for recovery and performance. It has been proposed that beverages containing protein, carbohydrates and electrolytes may attenuate exercise-induced fatigue and dehydration. Chocolate milk contains all of these nutrients and has recently drawn attention as a plausible post-exercise recovery drink. Therefore the aim of this study was to assess the efficacy of chocolate milk on post-exercise recovery markers. This review included 12 studies and a sub-analysis found significant improvements in time to exhaustion and lowered post-exercise blood-lactate. There were no significant differences between the other markers considered in the analysis. Based on these results, the authors deem chocolate milk to provide equivalent outcomes to placebo or other recovery drinks. As the available research is limited, the authors recommended high quality controlled trials with larger sample sizes be done to gain more clarity on best-practice for post-exercise recovery.
Abstract
BACKGROUND/OBJECTIVES Chocolate milk (CM) contains carbohydrates, proteins, and fat, as well as water and electrolytes, which may be ideal for post-exercise recovery. We systematically reviewed the evidence regarding the efficacy of CM compared to either water or other "sport drinks" on post-exercise recovery markers. SUBJECTS/METHODS PubMed, Scopus, and Google scholar were explored up to April 2017 for controlled trials investigating the effect of CM on markers of recovery in trained athletes. RESULTS Twelve studies were included in the systematic review (2, 9, and 1 with high, fair and low quality, respectively) and 11 had extractable data on at least one performance/recovery marker [7 on ratings of perceived exertion (RPE), 6 on time to exhaustion (TTE) and heart rate (HR), 4 on serum lactate, and serum creatine kinase (CK)]. The meta-analyses revealed that CM consumption had no effect on TTE, RPE, HR, serum lactate, and CK (P > 0.05) compared to placebo or other sport drinks. Subgroup analysis revealed that TTE significantly increases after consumption of CM compared to placebo [mean difference (MD) = 0.78 min, 95% confidence interval (CI): 0.27, 1.29, P = 0.003] and carbohydrate, protein, and fat-containing beverages (MD = 6.13 min, 95% CI: 0.11, 12.15, P = 0.046). Furthermore, a significant attenuation on serum lactate was observed when CM was compared with placebo (MD = -1.2 mmol/L, 95% CI: -2.06,-0.34, P = 0.006). CONCLUSION CM provides either similar or superior results when compared to placebo or other recovery drinks. Overall, the evidence is limited and high-quality clinical trials with more well-controlled methodology and larger sample sizes are warranted.
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The Role of Mineral and Trace Element Supplementation in Exercise and Athletic Performance: A Systematic Review.
Heffernan, SM, Horner, K, De Vito, G, Conway, GE
Nutrients. 2019;11(3)
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Minerals and trace elements (MTEs) are involved in hundreds of biological processes, and according to available population data many recommended amounts of MTEs are not being met. While MTEs are known to impact processes that are related to athletic performance, there is no consensus as to the efficacy of MTE supplementation and improved performance. The aim of this systematic review was to critically analyse the available evidence on MTE supplementation for enhancing athletic performance. According to 128 studies that met the inclusion criteria, iron and magnesium were the only two that demonstrated benefits. Based on the existing literature, the authors conclude there is insufficient evidence to suggest guidelines of MTEs to enhance athletic performance, and encourage high quality studies to investigate this further.
Abstract
Minerals and trace elements (MTEs) are micronutrients involved in hundreds of biological processes. Deficiency in MTEs can negatively affect athletic performance. Approximately 50% of athletes have reported consuming some form of micronutrient supplement; however, there is limited data confirming their efficacy for improving performance. The aim of this study was to systematically review the role of MTEs in exercise and athletic performance. Six electronic databases and grey literature sources (MEDLINE; EMBASE; CINAHL and SportDISCUS; Web of Science and clinicaltrials.gov) were searched, in accordance with PRISMA guidelines. Results: 17,433 articles were identified and 130 experiments from 128 studies were included. Retrieved articles included Iron (n = 29), Calcium (n = 11), Magnesium, (n = 22), Phosphate (n = 17), Zinc (n = 9), Sodium (n = 15), Boron (n = 4), Selenium (n = 5), Chromium (n = 12) and multi-mineral articles (n = 5). No relevant articles were identified for Copper, Manganese, Iodine, Nickel, Fluoride or Cobalt. Only Iron and Magnesium included articles of sufficient quality to be assigned as 'strong'. Currently, there is little evidence to support the use of MTE supplementation to improve physiological markers of athletic performance, with the possible exception of Iron (in particular, biological situations) and Magnesium as these currently have the strongest quality evidence. Regardless, some MTEs may possess the potential to improve athletic performance, but more high quality research is required before support for these MTEs can be given. PROSPERO preregistered (CRD42018090502).
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Micronutrient Status of Recreational Runners with Vegetarian or Non-Vegetarian Dietary Patterns.
Nebl, J, Schuchardt, JP, Ströhle, A, Wasserfurth, P, Haufe, S, Eigendorf, J, Tegtbur, U, Hahn, A
Nutrients. 2019;11(5)
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There is current debate as to whether plant-based nutrition can provide all the required nutrients in adequate amounts for athletes. The aim of this cross-sectional study was to evaluate the micronutrient status among omnivore, vegetarian and vegan recreational runners. In this study, fasting blood levels of vitamin B12, folate, vitamin D, iron, calcium, magnesium and zinc were assessed in 27 omnivores, 26 vegetarians and 28 vegans. These results showed there were no significant differences between vegan and vegetarian diets compared with the omnivore diet. Based on these results, the authors conclude a well-planned vegetarian and vegan diet, including supplementation, can meet the recreational runner’s requirements of important micronutrients. The authors suggest further research be done on a larger sample size and on athletes of differing levels of performance intensity.
Abstract
Vegetarian diets have gained popularity in sports. However, few data exist on the status of micronutrients and related biomarkers for vegetarian and vegan athletes. The aim of this cross-sectional study was to compare the micronutrient status of omnivorous (OMN, n = 27), lacto-ovo-vegetarian (LOV, n = 26), and vegan (VEG, n = 28) recreational runners. Biomarkers of vitamin B12, folate, vitamin D, and iron were assessed. Additionally, serum levels of calcium, magnesium, and zinc were examined. Lifestyle factors and supplement intake were recorded via questionnaires. About 80% of each group showed vitamin B12 adequacy with higher levels in supplement users. Mean red blood cell folate exceeded the reference range (>340 nmol/L) in all three groups (OMN: 2213 ± 444, LOV: 2236 ± 596, and VEG: 2354 ± 639 nmol/L; not significant, n.s.). Furthermore, vitamin D levels were comparable (OMN: 90.6 ± 32.1, LOV: 76.8 ± 33.7, and VEG: 86.2 ± 39.5 nmol/L; n.s.), and we found low prevalence (<20%) of vitamin D inadequacy in all three groups. Less than 30% of each group had depleted iron stores, however, iron deficiency anemia was not found in any subject. Our findings suggest that a well-planned, health-conscious lacto-ovo-vegetarian and vegan diet, including supplements, can meet the athlete's requirements of vitamin B12, vitamin D and iron.