ISSN Exercise & Sport Nutrition Review: Research & Recommendations

Nutritional priorities, practices and preferences of athletes and active individuals in the context of new product development in the sports nutrition sector

Introduction

Sports nutrition is a rapidly growing sector with increasing demand for evidence-based nutritional products to support competitive and healthy lifestyles. The product development process for novel foods should rely heavily on end-user engagement to facilitate future success, however there is a dearth of published information available. An understanding of the practices and self-reported nutritional priorities of athletes and active individuals is required for the development of new food products, facilitating evidence-based product formulation.

Methods

Participants were at least 18 years of age, actively participating in competitive sport or structured physical activity on at least two occasions per week. Participants were asked to undertake a comprehensive online survey assessing their nutritional practice, perceived nutritional priorities and preferences for product characteristics. Questions were developed on the basis of critical evaluation of the current scientific literature and the hosting of two scoping focus group sessions with prospective end-users.

Results

405 individuals (29 ± 9 years) completed this questionnaire. 295 participants reported active participation in competitive sport while the remaining 110 participants undertook structured physical activity exclusively. When asked to rank their top three most sought-after product claims in sports nutrition, "enhanced muscular recovery" was the most prioritised receiving 101 first choice preferences (25%) and 295 top 3 preferences. Fifty-eight percent of participants reported taking nutritional supplements. Caffeine containing functional foods (excluding caffeine supplements) were the most commonly used functional food group. A very low incidence of functional food usage was reported otherwise. When asked to rank the importance of various food product attributes, "nutritional profile" was ranked as the most important with rating of 3.37 ± 0.7 out of 4 followed by "taste" and "accessibility". Whole food nutritional products received the most first preference selections and most top 3 selections when presented with a number of popular performance and recovery products on the market.

Conclusions

The transition towards a food first approach in sports nutrition is vital for athletes and active individuals to achieve their goals; with the development of evidence-based functional foods, particularly with a focus on muscle recovery, endurance, and strength enhancement at the forefront for new food product design and innovation.

The effects of dietary nitrate supplementation on endurance exercise performance and cardiorespiratory measures in healthy adults: a systematic review and meta-analysis

BACKGROUND

Nitrate supplementation is thought to improve performance in endurance sports.

OBJECTIVE

To meta-analyze studies evaluating the effect of nitrate supplementation on endurance sports performance among adults.

DATA SOURCES

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Web of Science and CINAHL without language restrictions.

METHODS

We included studies that: 1) compared nitrate supplementation with placebo; 2) enrolled adults engaging in an endurance-based activity; and 3) reported a performance measure or surrogate physiologic outcome. We evaluated risk of bias using the Cochrane Collaboration tool and pooled data with a random-effects model. We used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to evaluate confidence in estimates.

RESULTS

We included 73 studies (n = 1061). Nitrate supplementation improved power output (MD 4.6 watts, P < 0.0001), time to exhaustion (MD 25.3 s, P < 0.00001), and distance travelled (MD 163.7 m, P = 0.03). We found no significant difference on perceived exertion, time trial performance and work done. Nitrate supplementation decreased VO₂ (MD - 0.04 L/min, P < 0.00001) but had no significant effect on VO_2max or blood lactate levels.

CONCLUSION

The available evidence suggests that dietary nitrate supplementation benefits performance-related outcomes for endurance sports.

Dietary practices of soccer athletes registered at the University of Limpopo, Limpopo Province, South Africa

Background

There is a growing number of athletes participating in soccer sports within the higher institutions of learning. However, studies involving the dietary practices of these athletes remain relatively scarce.

Objective

To determine the dietary practices of soccer athletes registered at the University of Limpopo, Limpopo Province, South Africa.

Methodology

This was a descriptive quantitative study, which adopted a purposive sampling technique to obtain 31 out of 40 registered soccer athletes representing the University of Limpopo as a team. The approval was obtained from the Turfloop Research and Ethics Committee (TREC). Data were collected at the University of Limpopo sports grounds, in the afternoons before the commencement of the training. The demographic status which included the gender, weight, and duration of athletes involved in sports of soccer at the University were collected. The weights of the athletes were also measured using a digital scale from SECA to calculate the nutrient requirements. The dietary practices of athletes were collected using the modified 24-h recall questionnaire on three different days. Athletes were required to recall all food items consumed in the previous 24 h. The researchers used household measuring utensils and food models to assist athletes in estimating food quantities. Athletes were required to recall incidences that took place in the previous to associate with food items taken. Food Frequency Questionnaire was used to determine the regularity of consumption of different food items. The nutrient intake for the athletes was obtained from the average analysis of the three 24-h recall questionnaires through MRC Food Finder (version 3.0). The SPSS software (24.0) was then used to determine descriptive tests expressing variables as percentages, means, standard deviations (± SD), and minimum and maximum values. The obtained test results were then compared to the recommendations by the International Society of Sports Nutrition (2018).

Results

Majority (81.0%) of athletes engaged in soccer sport for ≤ 2 years while at University. Overall, 61% of athletes consumed three meals/day. Only 65% consumed meals 2–3 h before the training. Majority of the athletes (≥ 61%) consumed carbohydrates, protein, and fat below the International Society of Sports Nutrition (ISSN) recommendations. Additionally, more than 65% of the same athletes consumed vitamins and minerals below the recommendations. None of the athletes consumed any food immediately after training.

Conclusion

The dietary intakes were below the ISSN recommendations. The dietary practices of athletes involved in the sport of soccer at the University of Limpopo were not adhering to soccer nutritional guidelines. Therefore, athletes need to receive nutrition support through the appointment of nutrition experts or dietitians to assist in nutrition and dietary related practices of athletes. Involvement of other multidisciplinary members is also warranted in sports of soccer and other sports categories to improve athletes’ performance without compromising their health.

Sports nutrition knowledge and perceptions among professional basketball athletes and coaches in Lebanon-a cross-sectional study

BACKGROUND

Basketball is the most popular sport in Lebanon. Adequate nutrition has been established to be a key component of optimal athletic performance, recovery from exercise and exercise-induced injury and documented to be associated with adequate nutrition knowledge (NK). In Lebanon, nutrition education is not incorporated into the basketball player training program and there is no established position for sports nutritionists in basketball clubs. To our knowledge, the present study is the first to evaluate the NK status of Division I Basketball (D1B) players /coaches in Lebanon. The objectives of this study are to assess the prevalence of inadequate NK; identify the gaps in NK, main sources of nutrition information, perceptions on sports nutrition and independent predictors of inadequate NK among D1B players and coaches in Lebanon.

METHODS

All D1B players (n = 184) and coaches (n = 16) in Lebanon were invited to participate in the study. Study participants were asked to complete a questionnaire that included questions on NK, resources and perceptions. A percentage of ≥60% of NK questions answered correctly was used as indicative of having adequate NK. Descriptive statistics were used to summarize the sample characteristics. The T-test and chi square test were used for comparisons of means and proportions, respectively. Logistic regression was used to explore the predictors of inadequate NK in D1B players.

RESULTS

The sample consisted of 178 D1B players (nM = 126; nF = 52) and 11 male coaches, resulting in survey response rates of 97 and 69%, respectively. Inadequate NK was found among about 80 and 54% of D1B players and coaches, respectively. Inadequate NK was found to be independently associated with lack of nutrition education in D1B players.

CONCLUSIONS

Despite widespread lack of adequate NK among D1B players and coaches in Lebanon, our sports clubs do not have dietitians. Basketball sports clubs in Lebanon should start to budget for hiring a dietitian or carrying out nutrition education campaigns that are based on analyses of incorrect responses of our study participants. Findings of this study are of tremendous significance to D1B players in Lebanon in terms of improving the athletes' physical health and performance.

The Impact of Nutrition Education Intervention with and Without a Mobile Phone Application on Nutrition Knowledge Among Young Endurance Athletes

Athletes often have significant gaps in their nutrition knowledge. Thus, the aim of this study was to investigate whether young Finnish endurance athletes' nutrition knowledge and dietary intake can be improved through an education intervention with or without a mobile food application. Seventy-nine endurance athletes, 18.0 years (SD: 1.4), participated in this randomized, controlled intervention. We compared the effects of participatory nutrition education sessions alone (group EDU) to those including the use of a mobile food application (group EDU + APP) for four days after each session. Both groups attended three 90-min education sessions fortnightly. The participants completed a validated nutrition knowledge questionnaire in Weeks 0, 5, and 17, and a three-day food diary in Weeks 0 and 17. The education plan was based on the Self-Determination Theory and the concept of meaningful learning process. The EDU group's nutrition knowledge scores were: 78 (week 0), 85 (week 5), and 84 (week 17) and the EDU + APP group's 78, 86, and 85, respectively. Nutrition knowledge increased significantly (main effect of time (p < 0.001)), but we observed no significant group × time interaction (p = 0.309). The changes in dietary intakes were minor (p > 0.05). The amount of carbohydrates was below endurance athletes' recommendations throughout the intervention. The reported energy intakes were also below the estimated energy expenditures. In conclusion, nutrition knowledge improved significantly after only three education sessions and food diary feedback, but the mobile app did not improve learning further. However, the nutrition education intervention alone was not enough to change dietary intake.

Dietary Supplement Intake and Associated Factors Among Gym Users in a University Community

Dietary supplement intake and associated factors among gym users in a university community in Sharjah, United Arab Emirates (UAE), were assessed using a structured, self-administered questionnaire in this cross-sectional study. Adults (N = 320) from five gyms in the University City of Sharjah participated in this cross-sectional study. The prevalence of dietary supplement intake was 43.8%. Statistically significant associations were found between the use of dietary supplements and sex (47.7% males, 28.1% females; p = .006), as well as weight lifting (88.6% taking supplements vs. 11.4% not taking supplements; p < .001), favoring male gym users. The reasons attributed to the use of dietary supplements varied between the sexes. Male exercisers used supplements to increase or maintain muscles mass, strength, and power and to boost exercise recovery. Females mainly used dietary supplements to increase energy, maintain their health, and prevent nutrition deficiency. Overall, protein supplements (whey proteins [48.6%] and protein powder [45.7%]) were among the most-consumed dietary supplements, followed by multivitamins (38.6%), branched-chain amino acids (36.4%), caffeine (35.0%), and creatine (29.3%). A widespread use of Internet-driven, self-prescribed dietary supplement intake was reported among gym users (60.7%). Only 12.8% of dietary supplement users sought information from dietitians. Practical implications suggest that gym instructors and coaches should be sufficiently trained to be able to provide accurate and scientifically sound information on dietary supplements to the exercisers in gyms in the university environment.

Micronutrient supplementation improves physical performance measures in Asian Indian school-age children

Micronutrients are important in physical work capacity and therefore performance. The impact of a multi-micronutrient-fortified nutritional beverage on physical performance measures among clinically healthy school-age children was assessed in a double-blind (for test and placebo groups), placebo-controlled, randomized trial in children aged between 7 and 10.5 y (n = 300). The participants with height- and weight-for-age Z-scores between 0 and ≥ -3 were randomized to 1 of 3 study arms: fortified choco-malt beverage powder (F), matched energy equivalent unfortified placebo (U), and untreated control (C). Participants in the F and C groups were given 40 g fortified (19 key vitamins and minerals) and unfortified choco-malt beverage, respectively, daily for 120 d. Primary efficacy outcomes included endurance and aerobic capacity using a 20-m shuttle test and step test. Other physical performance measures included speed (40-m sprint), visual reaction time, maximal hand grip, and forearm static endurance. Micronutrient status included thiamin, riboflavin, folate, niacin, iron, pyridoxal phosphate, and vitamins B-12 and C. All measurements were made at baseline and the end of the intervention. There was a within-subject increase in aerobic capacity and whole body endurance (P < 0.05) accompanied by a significant improvement in the status of iron thiamin, riboflavin, pyridoxal phosphate, folate, and vitamins C and B-12 in the F group compared to the within-subject changes in the other 2 groups (P < 0.05). The study suggests that multiple micronutrient supplementation in similar populations may be beneficial in improving micronutrient status and enhancing aerobic capacity and endurance in children.

Strength and hypertrophy responses to constant and decreasing rest intervals in trained men using creatine supplementation

Background

The purpose of the current study was to compare strength and hypertrophy responses to resistance training programs that instituted constant rest intervals (CI) and decreasing rest intervals (DI) between sets over the course of eight weeks by trained men who supplemented with creatine monohydrate (CR).

Methods

Twenty-two recreationally trained men were randomly assigned to a CI group (n = 11; 22.3 ± 1 years; 77.7 ± 5.4 kg; 180 ± 2.2 cm) or a DI group (n = 11; 22 ± 2.5 years; 75.8 ± 4.9 kg; 178.8 ± 3.4 cm). Subjects in both groups supplemented with CR; the only difference between groups was the rest interval instituted between sets; the CI group used 2 minutes rest intervals between sets and exercises for the entire 8-weeks of training, while the DI group started with a 2 minute rest interval the first two weeks; after which the rest interval between sets was decreased 15 seconds per week (i.e. 2 minutes decreasing to 30 seconds between sets). Pre- and post-intervention maximal strength for the free weight back squat and bench press exercises and isokinetic peak torque were assessed for the knee extensors and flexors. Additionally, muscle cross-sectional area (CSA) of the right thigh and upper arm was measured using magnetic resonance imaging.

Results

Both groups demonstrated significant increases in back squat and bench press maximal strength, knee extensor and flexor isokinetic peak torque, and upper arm and right thigh CSA from pre- to post-training (p ≤ 0.0001); however, there were no significant differences between groups for any of these variables. The total volume for the bench press and back squat were significantly greater for CI group versus the DI group.

Conclusions

We report that the combination of CR supplementation and resistance training can increase muscular strength, isokinetic peak torque, and muscle CSA, irrespective of the rest interval length between sets. Because the volume of training was greater for the CI group versus the DI group, yet strength gains were similar, the creatine supplementation appeared to bolster adaptations for the DI group, even in the presence of significantly less volume. However, further research is needed with the inclusion of a control group not receiving supplementation combined and resistance training with decreasing rest intervals to further elucidate such hypotheses.

Nutritional supplement use by elite young UK athletes: fallacies of advice regarding efficacy

BACKGROUND

The objective was to study nutritional supplement use among young elite UK athletes to establish whether a rationale versus practice incongruence exists, and to investigate the sources of information. Survey data were analysed for association between supplements used and motives for using such substances among young athletes along with the sources of advice and literature precedents on supplement effects.

METHODS

Participants were elite UK male and female athletes, within the age range between 12 and 21 (n = 403), mean age 17.66 +/- 1.99. Associations between type of supplements and reasons for using supplements were tested by calculating Pearson's chi2 and the strength of these symmetric associations shown by phi association coefficients.

RESULTS

Single supplement use was reported by 48.1%, with energy drinks being the most popular, consumed by 41.7% of all athletes and 86.6% of the supplement users in the sample. No agreement was observed between athletes' rationale and behaviour in relation to nutritional supplements except for creatine. Among health professionals, nutritionists and physiotherapists, followed by coaches, were most frequently consulted. Answers regarding reasons and supplements used showed incongruence and suggest widespread misinformation regarding supplements and their effects is an issue for the young athlete.

CONCLUSION

Widespread supplement taking behaviour was evidenced in the young elite athlete population with the most notable congruence between rationale and practice among young athletes being performance-related. Young athletes in the present sample appear to be less 'health conscious' and more 'performance focused' than their adult counterparts. Further research, using a full list of supplements, is warranted to test the hypothesis that health consciousness is less dominant in supplement choice by young athletes.

Atualizações sobre beta-hidroxi-beta-metilbutirato: suplementação e efeitos sobre o catabolismo de proteínas

O beta-hidroxi-beta-metilbutirato, metabólito do aminoácido leucina, vem sendo utilizado como suplemento alimentar, em situações específicas, com o intuito de aumentar ou manter a massa isenta de gordura. Os relatos dos efeitos do beta-hidroxi-beta-metilbutirato em estudos recentes fizeram crescer as expectativas sobre sua utilização em casos patológicos. Também foram demonstrados melhores resultados, quando da sua ingestão, no treinamento de força em indivíduos iniciantes e em idosos. Em humanos o beta-hidroxi-beta-metilbutirato tem sido usado como agente anti-catabólico, e em modelos animais foi demonstrado ser eficaz em inibir a atividade de vias proteolíticas em células musculares de indivíduos caquéticos in vitro e in vivo. Os mecanismos participantes desses processos envolvem: a inibição da atividade do sistema ubiquitina proteossoma ATP-dependente, a inibição de vias de sinalização com participação da proteína quinase C-alfa e a diminuição da concentração citoplasmática do fator nuclear - kappa B livre, eventos relacionados ao decréscimo da proteólise em células musculares.

Effects of arachidonic acid supplementation on training adaptations in resistance-trained males

Background

To determine the impact of AA supplementation during resistance training on body composition, training adaptations, and markers of muscle hypertrophy in resistance-trained males.

Methods

In a randomized and double blind manner, 31 resistance-trained male subjects (22.1 ± 5.0 years, 180 ± 0.1 cm, 86.1 ± 13.0 kg, 18.1 ± 6.4% body fat) ingested either a placebo (PLA: 1 g·day^-1 corn oil, n = 16) or AA (AA: 1 g·day^-1 AA, n = 15) while participating in a standardized 4 day·week^-1 resistance training regimen. Fasting blood samples, body composition, bench press one-repetition maximum (1RM), leg press 1RM and Wingate anaerobic capacity sprint tests were completed after 0, 25, and 50 days of supplementation. Percutaneous muscle biopsies were taken from the vastus lateralis on days 0 and 50.

Results

Wingate relative peak power was significantly greater after 50 days of supplementation while the inflammatory cytokine IL-6 was significantly lower after 25 days of supplementation in the AA group. PGE₂ levels tended to be greater in the AA group. However, no statistically significant differences were observed between groups in body composition, strength, anabolic and catabolic hormones, or markers of muscle hypertrophy (i.e. total protein content or MHC type I, IIa, and IIx protein content) and other intramuscular markers (i.e. FP and EP₃ receptor density or MHC type I, IIa, and IIx mRNA expression).

Conclusion

AA supplementation during resistance-training may enhance anaerobic capacity and lessen the inflammatory response to training. However, AA supplementation did not promote statistically greater gains in strength, muscle mass, or influence markers of muscle hypertrophy.

Performance enhancement with supplements: incongruence between rationale and practice

BACKGROUND

Athletes are expected to consider multiple factors when making informed decision about nutritional supplement use. Besides rules, regulations and potential health hazards, the efficacy of different nutritional supplements in performance enhancement is a key issue. The aim of this paper was to find evidence for informed decision making by investigating the relationship between specific performance-related reasons for supplement use and the reported use of nutritional supplements.

METHODS

The 'UK Sport 2005 Drug Free Survey' data (n = 874) were re-analysed using association [chi2] and 'strength of association' tests [varphi] to show the proportion of informed choices and to unveil incongruencies between self-reported supplement use and the underlying motives.

RESULTS

Participants (n = 520) reported supplement use in the pattern of: vitamin C (70.4%), creatine (36.1%), whey protein (30.6%), iron (29.8%), caffeine (23.8%), and ginseng (8.3%) for the following reasons: strength maintenance (38.1%), doctors' advice (24.2%), enhancing endurance (20.0%), ability to train longer (13.3%), and provided by the governing body (3.8%). Of thirty possible associations between the above supplements and reasons, 11 were predictable from literature precedents and only 8 were evidenced and these were not strong (varphi < .7). The best associations were for the ability to train longer with creatine (reported by 73.9%, chi2 = 49.14, p < .001; varphi = .307, p < .001), and maintaining strength with creatine (reported by 62.6%, chi2 = 97.08, p < .001; varphi = .432, p < .001) and whey protein (reported by 56.1%, chi2 = 97.82, p < .001; varphi = .434, p < .001).

CONCLUSION

This study provided a platform for assessing congruence between athletes' reasons for supplement use and their actual use. These results suggest that a lack of understanding exists in supplement use. There is an urgent need to provide accurate information which will help athletes make informed choices about the use of supplements.

Limited agreement exists between rationale and practice in athletes' supplement use for maintenance of health: a retrospective study

Background

The widespread use of nutritional supplements among athletes is poorly understood. The prevalence of supplement intake and users' knowledge have been researched independently leading to useful, but disconnected, information on supplement use.

Methods

The 'UK Sport 2005 Drug Free Survey' data (n = 874) were re-analysed using association [χ²] and 'strength of association' tests [φ], to discover observed incongruencies between self-reported supplement use and the underlying motives. Results are given for test pairs between 'motive for use' [doctor's advice, avoiding sickness, overcoming injuries and enhancement of diet] and each supplement used and these were categorized as strong (φ > .7), intermediate (7 < φ > .3) and weak (φ < .3).

Results

The use of selected supplements varied widely as follows: multivitamin (72.7%), vitamin C (70.4%), echinacea (30.8%), iron (29.8%), magnesium (11.0%) and ginseng (8.3%). Associations with motive were found in 8 of the 10 test pairs which were expected from literature precedents, however only weak associations exist. Of these, four were associated with avoidance of sickness [iron (χ² = 11.94, p < .001; φ = .15, p = .001), multivitamin (χ² = 6.43, p < .001; φ = .11, p = .011), vitamin C (χ² = 54.67, p < .001; φ = .32, p < .001) and echinacea (χ² = 40.34, p < .001; φ = .28, p < .001)]. The remaining 4 associations were: no time to prepare meals with ginseng (χ² = 7.64, p = .006; φ = .12, p = .006) and multivitamin (χ² = 9.103, p = .003; φ = .13, p = .003); overcoming injuries with magnesium (χ² = 6.99, p = .008; φ = .11, p = .008); doctors' advice and iron (χ² = 35.00, p < .001; φ = .25, p = .001).

Conclusion

These results suggest a lack of understanding regarding supplements and health maintenance, except for vitamin C and echinacea. Furthermore, supplement use is apparently independent of physicians/dieticians' advice, except for iron. This may suggest a widespread circumvention of expert advice in the growing area of supplement use and therefore should be addressed to underscore potential health risks.

International Society of Sports Nutrition position stand: protein and exercise

Position Statement

The following seven points related to the intake of protein for healthy, exercising individuals constitute the position stand of the Society. They have been approved by the Research Committee of the Society. 1) Vast research supports the contention that individuals engaged in regular exercise training require more dietary protein than sedentary individuals. 2) Protein intakes of 1.4 – 2.0 g/kg/day for physically active individuals is not only safe, but may improve the training adaptations to exercise training. 3) When part of a balanced, nutrient-dense diet, protein intakes at this level are not detrimental to kidney function or bone metabolism in healthy, active persons. 4) While it is possible for physically active individuals to obtain their daily protein requirements through a varied, regular diet, supplemental protein in various forms are a practical way of ensuring adequate and quality protein intake for athletes. 5) Different types and quality of protein can affect amino acid bioavailability following protein supplementation. The superiority of one protein type over another in terms of optimizing recovery and/or training adaptations remains to be convincingly demonstrated. 6) Appropriately timed protein intake is an important component of an overall exercise training program, essential for proper recovery, immune function, and the growth and maintenance of lean body mass. 7) Under certain circumstances, specific amino acid supplements, such as branched-chain amino acids (BCAA's), may improve exercise performance and recovery from exercise.