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Can dementia risk be reduced by following the American Heart Association's Life's Simple 7? A systematic review and dose-response meta-analysis.
Wu, J, Xiong, Y, Xia, X, Orsini, N, Qiu, C, Kivipelto, M, Rizzuto, D, Wang, R
Ageing research reviews. 2023;83:101788
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The American Heart Association (AHA) has defined ideal levels of seven modifiable cardiovascular health (CVH) factors, known as Life's Simple 7, that consist of smoking, physical activity, diet, body mass index, fasting blood glucose, total cholesterol, and blood pressure. Maintaining ideal levels of these factors has been recommended as a prevention strategy against not only cardiovascular diseases but also neurodegenerative disorders, e.g., cognitive decline and dementia. However, studies exploring the beneficial effects of the AHA’s CVH metrics on cognitive outcomes, especially among older populations, have been uncertain, and solid evidence is lacking in this field. This systematic review and meta-analysis aimed to quantify the relationship between the AHA’s CVH metrics and cognitive outcomes. 14 longitudinal studies were included in the meta-analysis. The results showed a considerable effect of a favourable total CVH score on reduced risk of incident dementia in adults aged 70 years or older. When looking at the individual factors, dementia risk can be reduced significantly if older adults achieved the recommended level of physical activity, blood glucose, or total cholesterol. The association with smoking appeared to be borderline, and there was no association between diet, body mass index hazard ratio or blood pressure and dementia risk. The authors concluded that their findings provide evidence that maintaining a favourable level of CVH score, either in mid- or late- life, would substantially reduce the risk of dementia among older adults. Preserving cardiovascular health by quitting smoking, engaging in physical exercise, controlling blood glucose and total cholesterol might be especially effective for forestalling cognitive decline and dementia.
Abstract
This study aimed to quantify the relationships between the American Heart Association (AHA) Cardiovascular Health (CVH) metrics, namely AHA Life's Simple 7, and cognitive outcomes. We searched PubMed and Embase (January 1, 2010-August 24, 2022) and finally included 14 longitudinal studies (311654 participants with 8006 incident dementia cases). Random-effects meta-analysis and one-stage linear mixed-effects models were performed. Increased CVH score seemed to associate with decreased risk of incident dementia in a linear manner, but this relationship varied by the measurement age of CVH metrics. That is, midlife CVH tended to have a linear association with late-life dementia risk, whereas a J-shaped association was observed between the late-life CVH score and dementia. In addition, late-life dementia risk was reduced significantly if individuals maintained an ideal level of AHA's CVH guidelines of physical activity, fasting plasma glucose, total cholesterol, and smoking. However, our meta-analysis did not show a significant association between CVH score and global cognitive decline rate. Following AHA's CVH guidelines and maintaining CVH at an optimal level would substantially reduce the late-life dementia risk. More research is required to explore the link between a favorable CVH score and cognitive trajectories among cognitively asymptomatic older populations.
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Nutrition and Exercise Interventions to Improve Body Composition for Persons with Overweight or Obesity Near Retirement Age: A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials.
Eglseer, D, Traxler, M, Embacher, S, Reiter, L, Schoufour, JD, Weijs, PJM, Voortman, T, Boirie, Y, Cruz-Jentoft, A, Bauer, S
Advances in nutrition (Bethesda, Md.). 2023;14(3):516-538
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Obesity is characterised by excessive fat accumulation that often occurs during the process of aging. Aging is accompanied not only by a gradual increase in body fat stores but also a decrease in muscle mass, muscle function, and water retention. The aim of this study was to assess which nutrition and exercise interventions are most effective for improving the body composition (fat mass and muscle mass), body mass index, and waist circumference in persons with overweight or obesity near retirement age (55 to 70 years of age). This study was a systematic review and network meta-analysis (NMA) of randomised controlled trials of sixty-six studies. Results of the NMA showed that the most effective strategy to improve body composition, i.e., losing fat without increasing risk of sarcopenia in persons with obesity around retirement age, was combining energy restriction with resistance training or with mixed exercise (resistance combined with aerobic exercise) and/or high-protein intake. In fact, without training, an energy-restricted diet with or without added protein helped individuals lose fat mass but also tended to result in losses of muscle mass. Authors conclude that an energy-restricted diet alone probably contributes to the development of sarcopenic obesity in persons of retirement age. Thus, to simultaneously lose weight and maintain muscle mass, authors recommend a combination of energy restriction and resistance training.
Abstract
The retirement phase is an opportunity to integrate healthy (nutrition/exercise) habits into daily life. We conducted this systematic review to assess which nutrition and exercise interventions most effectively improve body composition (fat/muscle mass), body mass index (BMI), and waist circumference (WC) in persons with obesity/overweight near retirement age (ages 55-70 y). We conducted a systematic review and network meta-analysis (NMA) of randomized controlled trials, searching 4 databases from their inception up to July 12, 2022. The NMA was based on a random effects model, pooled mean differences, standardized mean differences, their 95% confidence intervals, and correlations with multi-arm studies. Subgroup and sensitivity analyses were also conducted. Ninety-two studies were included, 66 of which with 4957 participants could be used for the NMA. Identified interventions were clustered into 12 groups: no intervention, energy restriction (i.e., 500-1000 kcal), energy restriction plus high-protein intake (1.1-1.7 g/kg/body weight), intermittent fasting, mixed exercise (aerobic and resistance), resistance training, aerobic training, high protein plus resistance training, energy restriction plus high protein plus exercise, energy restriction plus resistance training, energy restriction plus aerobic training, and energy restriction plus mixed exercise. Intervention durations ranged from 8 wk to 6 mo. Body fat was reduced with energy restriction plus any exercise or plus high-protein intake. Energy restriction alone was less effective and tended to decrease muscle mass. Muscle mass was only significantly increased with mixed exercise. All other interventions including exercise effectively preserved muscle mass. A BMI and/or WC decrease was achieved with all interventions except aerobic training/resistance training alone or resistance training plus high protein. Overall, the most effective strategy for nearly all outcomes was combining energy restriction with resistance training or mixed exercise and high protein. Health care professionals involved in the management of persons with obesity need to be aware that an energy-restricted diet alone may contribute to sarcopenic obesity in persons near retirement age. This network meta-analysis is registered at https://www.crd.york.ac.uk/prospero/ as CRD42021276465.
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Physical Exercise and Dietary Supplementation in Middle-Aged and Older Women: A Systematic Review.
Sánchez-García, JC, López Hernández, D, Piqueras-Sola, B, Cortés-Martín, J, Reinoso-Cobo, A, Menor-Rodríguez, MJ, Rodríguez-Blanque, R
Journal of clinical medicine. 2023;12(23)
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Menopause is a process that marks the end of the reproductive phase in women. Menopause means both that the ovaries stop producing eggs and that there is a sharp decline in the production of female hormones such as progesterone and oestrogen. The aim of this study was to discuss the benefits of exercise and dietary supplements during menopause. This study was a systematic review of ten articles. Results showed that: - both strength and aerobic training, as well as supplementation with calcium and vitamin D, increase bone mineral density. - combined strength and resistance training provide cardiovascular benefits, increase strength and muscle mass, and reduce the risk of sarcopenia. - physical exercise has a synergistic effect with some supplements, enhancing their effectiveness. Authors concluded that physical exercise can help combat many of the symptoms associated with menopause, providing benefits for a more vital menopause and a more vital old age.
Abstract
UNLABELLED With the aging of the population in developed countries, the number of middle-aged and older women is progressively increasing. During this stage, women suffer from a number of signs and symptoms that could be reduced or treated with physical exercise and dietary supplements. The main objective of this study was to analyse the benefits of exercise and dietary supplements during menopause. MATERIALS AND METHODS A systematic review of the scientific literature was performed according to the PRISMA 2020 protocol, searching the PubMed, Cochrane, Scopus, and WOS databases. Studies that met the inclusion criteria were assessed for methodological quality using the PEDro or AMSTAR-2 scales. RESULTS The searches yielded a total of 104 results, of which 10 were selected, with methodological quality ranging from fair to excellent. Each article examined the combination of a dietary supplement plan versus a placebo; plus an exercise routine versus another routine or a sedentary lifestyle. The results showed the benefits of combining a nutritional supplementation plan with an exercise routine during menopause. CONCLUSIONS The practice of weekly strength and endurance exercises, together with the consumption of certain dietary supplements, may be a good resource for coping with menopause in a healthy way.
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Does adding exercise or physical activity to pharmacological osteoporosis therapy in patients with increased fracture risk improve bone mineral density and lower fracture risk? A systematic review and meta-analysis.
Schumm, AK, Craige, EA, Arora, NK, Owen, PJ, Mundell, NL, Buehring, B, Maus, U, Belavy, DL
Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA. 2023;34(11):1867-1880
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Osteoporosis, a progressive systematic skeletal disease is caused by diminished bone density and strength, which may increase the risk of fragility fractures in the spine, pelvis, femur etc. Women are at greater risk of developing osteoporosis. Osteopenia is an intermediary stage of reduced bone mineral density before progressing into the osteoporosis disease state. Exercise and pharmacological therapies are considered two effective strategies commonly used in the treatment of osteoporosis. Exercise may help to improve bone mineral density, strength and muscle mass and reduce the risk of fractures. This systematic review and meta-analysis of five parallel-arm randomised controlled trials investigated the combined effect of exercise and pharmacological therapy on bone mineral density, bone turnover markers, fractures and fracture healing in patients with osteopenia and osteoporosis. This systematic review and meta-analysis showed a non-significant improvement in bone mineral density in patients with osteopenia and osteoporosis followed by combined pharmacological treatment with exercise. Pharmacological therapy alone showed improvement and maintenance of bone mineral density. There was no evidence for the improvement in fragility fracture healing. Due to the low evidence and high heterogeneity of included studies, further robust studies are required to evaluate the combined effect of exercise and pharmacological therapy in people with systematic skeletal disease. Healthcare professionals can use this study to understand the benefits of pharmacological therapy in improving osteoporosis and osteopenia and the potential of adding exercise as a therapeutic strategy in clinical practice.
Abstract
This prospectively registered systematic review and meta-analysis examines whether exercise (EX) training has an additive effect to osteoanabolic and/or antiresorptive pharmacological therapy (PT) in people with osteoporosis on bone mineral density (BMD), bone turnover markers (BTMs), fracture healing, and fractures. Four databases (inception to 6 May 2022), 5 trial registries, and reference lists were searched. Included were randomized controlled trials comparing the effect of EX + PT vs. PT with regard to BMD, BTM, fracture healing, and fractures. Risk of bias was assessed using the Cochrane RoB2 and certainty of evidence by the GRADE approach. Random-effects meta-analysis with Hartung-Knapp-Sidik-Jonkman adjustment was used to estimate standardized mean differences and 95% confidence intervals. Out of 2593 records, five RCTs with 530 participants were included. Meta-analysis showed with very low certainty evidence and wide confidence intervals that EX + PT compared to PT had larger effect sizes for BMD at 12 months at the hip (SMD [95%CI]: 0.18 [- 1.71; 2.06], n = 3 studies), tibia (0.25 [- 4.85; 5.34], n = 2), lumbar spine (0.20 [- 1.15; 1.55], n = 4), and forearm (0.05 [- 0.35; 0.46], n = 3), but not femoral neck (- 0.03 [- 1.80; 1.75], n = 3). Furthermore, no improvement was revealed for BTM such as bone ALP (- 0.68 [- 5.88; 4.53], n = 3), PINP (- 0.74 [- 10.42; 8.93], n = 2), and CTX-I (- 0.69 [- 9.61; 8.23], n = 2), but with very wide confidence intervals. Three potentially relevant ongoing trials were identified via registries. No data were found for fracture healing or fracture outcomes. It remains unclear whether EX has an additive impact to PT in people with osteoporosis. High-quality, adequately powered, targetted RCTs are required. PROTOCOL REGISTRATION PROSPERO CRD42022336132.
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Absence of Effects of L-Arginine and L-Citrulline on Inflammatory Biomarkers and Oxidative Stress in Response to Physical Exercise: A Systematic Review with Meta-Analysis.
Porto, AA, Gonzaga, LA, Benjamim, CJR, Valenti, VE
Nutrients. 2023;15(8)
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L-citrulline is a non-essential amino acid that acts as a precursor to L-arginine. L-arginine is a semi-essential amino acid used for nitric oxide production which is crucial for maintaining physiological function and immune regulation. Previous research has shown that L-citrulline and L-arginine supplementation may offer antioxidant and anti-inflammatory benefits in reducing exercise-related oxidative stress and inflammation. This systematic review and meta-analysis included seven randomised controlled trials to investigate the effect of L-citrulline and L-arginine on antioxidants, oxidative stress, and inflammatory and anti-inflammatory markers. This systematic review and meta-analysis showed no significant improvements in oxidative stress and inflammation followed by the supplementation of L-citrulline and L-arginine before exercise. However, further robust studies that include different dosages and exercise intensities are required to assess the beneficial effects of L-citrulline and L-arginine supplements to support physical exercise-induced oxidative stress and inflammation due to the heterogeneity of the included studies. Healthcare professionals can use the results of this study to understand the potential benefits of L-citrulline and L-arginine supplementation in people prone to producing proinflammatory cytokines.
Abstract
The repercussions on oxidative and inflammatory stress markers under the effects of arginine and citrulline in response to exercise are not fully reached. We completed a systematic review to investigate the effects of L-Citrulline or L-Arginine on oxidative stress and inflammatory biomarkers following exercise. EMBASE, MEDLINE (PubMed), Cochrane Library, CINAHL, LILACS, and Web of Science databases were used to record the trials. This study includes randomized controlled trials (RCTs) and non-RCTs with subjects over 18 years old. Those under the intervention protocol consumed L-Citrulline or L-Arginine, and the controls ingested placebo. We recognized 1080 studies, but only 7 were included (7 studies in meta-analysis). We observed no difference between pre- vs. post-exercise for oxidative stress (subtotal = -0.21 [CI: -0.56, 0.14], p = 0.24, and heterogeneity = 0%. In the sub-group "L-Arginine" we found a subtotal = -0.29 [-0.71, 0.12], p = 0.16, and heterogeneity = 0%. For the "L-Citrulline" subgroup we observed a subtotal = 0.00 [-0.67, 0.67], p = 1.00, and heterogeneity was not applicable. No differences were observed between groups (p = 0.47), and I² = 0%) or in antioxidant activity (subtotal = -0.28 [-1.65, 1.08], p = 0.68, and heterogeneity = 0%). In the "L-Arginine" sub-group, we found a subtotal = -3.90 [-14.18, 6.38], p = 0.46, and heterogeneity was not applicable. For the "L-Citrulline" subgroup, we reported a subtotal = -0.22 [-1.60, 1.16], p = 0.75, and heterogeneity was not applicable. No differences were observed between groups (p = 0.49), and I² = 0%), inflammatory markers (subtotal = 8.38 [-0.02, 16.78], p = 0.05, and heterogeneity = 93%. Tests for subgroup differences were not applicable, and anti-inflammatory markers (subtotal = -0.38 [-1.15, 0.39], p = 0.34 and heterogeneity = 15%; testing for subgroup differences was not applicable). In conclusion, our systematic review and meta-analysis found that L-Citrulline and L-Arginine did not influence inflammatory biomarkers and oxidative stress after exercise.
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Time of the day of exercise impact on cardiovascular disease risk factors in adults: a systematic review and meta-analysis.
Sevilla-Lorente, R, Carneiro-Barrera, A, Molina-Garcia, P, Ruiz, JR, Amaro-Gahete, FJ
Journal of science and medicine in sport. 2023;26(3):169-179
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In humans, shifted sleep patterns seem to interfere with several metabolic pathways. Shift work, short sleep duration, exposure to artificial light, inadequate eating time window, and lack of physical activity, are some characteristics of the modern lifestyle that contributes to the occurrence and worsening of cardiovascular disease (CVD). The aim of this study was to analyse the time of the day of exercise-induced effects on CVD risk factors in adults. This study was a systematic review and meta-analysis of twenty-two studies. Results showed that exercise produces an acute reduction of systolic blood pressure independently of the time of the day at which it is performed. Similarly, exercise produces an acute increase in blood glucose independently of the time of the day. Authors concluded that further research is needed to establish whether there is a diurnal variation of exercise on cardiovascular health and how it is related to health status, sex, or the type of exercise.
Abstract
OBJECTIVES To compare the effect of a single bout of morning vs. evening exercise on cardiovascular risk factors in adults. DESIGN Systematic review and meta-analysis. METHODS A systematic search of studies was conducted using PubMed and Web of Science from inception to June 2022. Selected studies accomplished the following criteria: crossover design, acute effect of exercise, blood pressure, blood glucose, and/or blood lipids as the study's endpoint, a washout period of at least 24 h, and adults. Meta-analysis was performed by analyzing: 1) separated effect of morning and evening exercise (pre vs. post); and 2) comparison between morning and evening exercise. RESULTS A total of 11 studies were included for systolic and diastolic blood pressure and 10 studies for blood glucose. Meta-analysis revealed no significant difference between morning vs. evening exercise for systolic blood pressure (g ∆ = 0.02), diastolic blood pressure (g ∆ = 0.01), or blood glucose (g ∆ = 0.15). Analysis of moderator variables (age, BMI, sex, health status, intensity and duration of exercise, and hour within the morning or evening) showed no significant morning vs. evening effect. CONCLUSIONS Overall, we found no influence of the time of the day on the acute effect of exercise on blood pressure neither on blood glucose.
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Effects of Different Therapeutic Exercise Modalities on Migraine or Tension-Type Headache: A Systematic Review and Meta-Analysis with a Replicability Analysis.
Varangot-Reille, C, Suso-Martí, L, Romero-Palau, M, Suárez-Pastor, P, Cuenca-Martínez, F
The journal of pain. 2022;23(7):1099-1122
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For individuals who suffer from headaches and migraines, the first treatment option is usually drug based, which has been associated with side effects, dependency, and abuse of medications. Exercise may be of benefit to individuals with headache and migraine, as it can stimulate the release of chemicals in the brain, which are beneficial to coping with pain. The aim of this systematic review and meta-analysis was to determine the effect of exercise in comparison to non-active treatment for pain, frequency of headache episodes, headache duration, quality of life and medication use in individuals with migraine or tension headache. The results showed that both aerobic and strength training were of benefit to the intensity of pain, which resulted in a decrease in medication use. Strength training was marginally better for pain than aerobic exercise, however the research that this was based on was of low quality. It was concluded that exercise could be considered a treatment option for those with migraine and headaches, however the evidence that this was based on was of low quality and so more research is needed before clinical recommendations could be made. This study could be used by healthcare professionals to understand that there may be some benefit of exercise for the management of pain in individuals who have migraines and headaches.
Abstract
The primary aim of this study was to review the effect of exercise in comparison with a non-active treatment on pain intensity, frequency of headache episodes, headache duration, quality of life, medication use, and psychological symptoms, in patients with migraine or tension-type headache (TTH). A systematic search was conducted in various electronic databases to identify all relevant studies: Medline (PubMed), PEDro, EBSCO and Google Scholar. Clinical trials assessing the effects of exercise interventions in patients with primary headaches were selected. Methodological quality was evaluated using the Cochrane Risk of Bias Tool and PEDro scale and qualitative analysis was based on classifying the results into levels of evidence according to the GRADE. 19 studies (2776 participants; 85% female) were included. The meta-analysis showed statistically significant differences in pain intensity for aerobic training in patients with migraine (SMD = -0.65; 95% CI = -1.07 to -0.22, very low certainty evidence) and for strength training in patients with TTH (SMD = -0.84; 95% CI = -1.68 to- -0.01, very low certainty evidence). Statistically significant differences were also found in the medication use (SMD = -0.51; 95% CI = -0.85 to -0.17, low certainty evidence). Low transparency, replicability and high risk of bias were found. Aerobic training has a small to moderate clinical effect on pain intensity and medication use on migraine patients, with very low to low certainty of evidence. Strength training showed a moderate clinical effect with very low quality of evidence in patients with TTH. Exercise could be considered as clinically relevant for the management of patients with primary headaches, but the presence of low certainty of evidence and low transparency and replicability limited its clinical application. PERSPECTIVE This article presents current evidence about exercise interventions in patients with primary headaches, including migraine and tension-type headache. Existing findings are reviewed, and relevant data are provided on the effectiveness of each exercise modality, as well as its certainty of evidence and clinical applicability.
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Effects of Attentional Focus on Muscular Endurance: A Meta-Analysis.
Grgic, J, Mikulic, P
International journal of environmental research and public health. 2021;19(1)
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For over 20 years, the effects of attentional focus on motor learning have been explored. Several muscular qualities are important when discussing resistance exercise, including muscular endurance. The aim of this study was to perform a meta-analysis examining the effects of external focus vs. internal focus vs. control on muscular endurance. This study is a meta-analysis of five studies. The pooled number of participants among the included studies was 141 (24 females and 117 males). Results indicate that adopting an external focus of attention enhances muscular endurance. These performance-enhancing effects of external focus were found when comparing both with an internal focus and control condition. However, there was no significant difference between the internal focus and control conditions. Authors conclude that individuals should use an external focus of attention for acute enhancement of muscular endurance.
Abstract
Several studies explored the effects of attentional focus on resistance exercise, but their analysed outcomes most commonly involved surface electromyography variables. Therefore, the effects of attentional focus on resistance exercise performance remain unclear. The aim of this review was to perform a meta-analysis examining the acute effects of external focus vs. internal focus vs. control on muscular endurance. Five databases were searched to find relevant studies. The data were pooled in a random-effects meta-analysis. In the analysis for external vs. internal focus of attention, there were seven comparisons with 14 study groups. In the analyses for external focus vs. control and internal focus vs. control, there were six comparisons with 12 study groups. An external focus of attention enhanced muscular endurance when compared with an internal focus (Cohen's d: 0.58; 95% confidence interval (CI): 0.34 and 0.82) and control (Cohen's d: 0.42; 95% CI: 0.08 and 0.76). In the analysis for internal focus vs. control, there was no significant difference between the conditions (Cohen's d: -0.19; 95% CI: -0.45 and 0.07). Generally, these results remained consistent in the subgroup analyses for upper-body vs. lower-body exercises. From a practical perspective, the results presented in this review suggest that individuals should use an external focus of attention for acute enhancement of muscular endurance.
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Effect of food sources of nitrate, polyphenols, L-arginine and L-citrulline on endurance exercise performance: a systematic review and meta-analysis of randomised controlled trials.
d'Unienville, NMA, Blake, HT, Coates, AM, Hill, AM, Nelson, MJ, Buckley, JD
Journal of the International Society of Sports Nutrition. 2021;18(1):76
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Nitric oxide (NO) is a molecule that is found in some foods and is involved in muscle function and repair. Given this fact, increased dietary NO intake to improve endurance exercise performance has become popular. The aim of this systematic review and meta-analysis was to determine the effect of consuming foods rich in precursors to NO synthesis on endurance exercise performance. 118 studies were found, with the majority looking at polyphenols, which are micronutrients found in plants, and nitrates. A small number of studies were found on L-citrulline, which is a natural compound mainly found in watermelon. Diets rich in L-citrulline showed little effect on endurance exercise performance and those rich in polyphenols and nitrates had a small effect on exercise performance. Different foods were shown to have different effects with nitrate-rich foods such as beetroot showing a small benefit, but not red spinach, Swiss chard, or rhubarb. Amongst polyphenol rich foods, a small benefit was seen with grape, beetroot, French maritime pine, Montmorency cherry and pomegranate, whilst no benefits were evident for New Zealand blackcurrant, cocoa, ginseng, green tea, or raisins. Well-trained males showed benefits from polyphenols but not nitrate rich foods. It was concluded that foods rich in polyphenols and nitrates may have a small benefit on endurance exercise performance, but this effect may be food specific. Highly trained males may only find a benefit from a polyphenol rich diet. This study could be used by healthcare professionals to understand that foods rich in precursors involved in the production of NO may have a limited effect on endurance exercise performance and that it may be dependent upon the food given and the level of fitness.
Abstract
BACKGROUND Increasing nitric oxide bioavailability may induce physiological effects that enhance endurance exercise performance. This review sought to evaluate the performance effects of consuming foods containing compounds that may promote nitric oxide bioavailability. METHODS Scopus, Web of Science, Ovid Medline, EMBASE and SportDiscus were searched, with included studies assessing endurance performance following consumption of foods containing nitrate, L-arginine, L-citrulline or polyphenols. Random effects meta-analysis was conducted, with subgroup analyses performed based on food sources, sex, fitness, performance test type and supplementation protocol (e.g. duration). RESULTS One hundred and eighteen studies were included in the meta-analysis, which encompassed 59 polyphenol studies, 56 nitrate studies and three L-citrulline studies. No effect on exercise performance following consumption of foods rich in L-citrulline was identified (SMD=-0.03, p=0.24). Trivial but significant benefits were demonstrated for consumption of nitrate and polyphenol-rich foods (SMD=0.15 and 0.17, respectively, p<0.001), including performance in time-trial, time-to-exhaustion and intermittent-type tests, and following both acute and multiple-day supplementation, but no effect of nitrate or polyphenol consumption was found in females. Among nitrate-rich foods, beneficial effects were seen for beetroot, but not red spinach or Swiss chard and rhubarb. For polyphenol-rich foods, benefits were found for grape, (nitrate-depleted) beetroot, French maritime pine, Montmorency cherry and pomegranate, while no significant effects were evident for New Zealand blackcurrant, cocoa, ginseng, green tea or raisins. Considerable heterogeneity between polyphenol studies may reflect food-specific effects or differences in study designs and subject characteristics. Well-trained males (V̇O2max ≥65 ml.kg.min-1) exhibited small, significant benefits following polyphenol, but not nitrate consumption. CONCLUSION Foods rich in polyphenols and nitrate provide trivial benefits for endurance exercise performance, although these effects may be food dependent. Highly trained endurance athletes do not appear to benefit from consuming nitrate-rich foods but may benefit from polyphenol consumption. Further research into food sources, dosage and supplementation duration to optimise the ergogenic response to polyphenol consumption is warranted. Further studies should evaluate whether differential sex-based responses to nitrate and polyphenol consumption are attributable to physiological differences or sample size limitations. OTHER The review protocol was registered on the Open Science Framework ( https://osf.io/u7nsj ) and no funding was provided.
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Impact of Probiotics on the Performance of Endurance Athletes: A Systematic Review.
Díaz-Jiménez, J, Sánchez-Sánchez, E, Ordoñez, FJ, Rosety, I, Díaz, AJ, Rosety-Rodriguez, M, Rosety, MÁ, Brenes, F
International journal of environmental research and public health. 2021;18(21)
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The relationship between the gut microbiome and exercise has recently been explored to ascertain potential methods of improving athletic performance. Athletes have begun utilising probiotics to improve performance, support the immune system and reduce gastrointestinal problems, however no systematic review has been done to assess the efficacy behind these notions. The aim of this study is to review the use of probiotics in endurance athletes and assess both the direct and indirect associative factors. This review included nine studies and found improvements in athletic performance, oxidative stress markers, immune support, and incidence of upper respiratory tract infections with probiotic use. While there is little scientific evidence on the causative relationship between probiotics and performance, the authors conclude probiotics can enhance athletic performance by ameliorating the indirect consequences of oxidative stress and infection.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Endurance athletes may take probiotic supplements to support immune or GI health or for other reasons
- Currently there is little evidence that probiotics directly or specifically enhance athletic performance
- Probiotic supplementation potentially impacts on immune health particularly during intensive training and may facilitate muscle recovery or maintain performance
- Whilst probiotics may reduced GI symptom frequency and severity, further research is clearly warranted
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
- There is current interest in the potential therapeutic benefits of probiotic strategies to support training and in-race performance for endurance athletes.
- Probiotic supplements are typically used by endurance athletes to limit or prevent upper respiratory tract infections (URTIs), reduce oxidative stress, support the immune system and modulate gastrointestinal function.
- Based on a limited number of articles sourced in this review (n=26), only 9 met the underlying quality and inclusion criteria. This highlights an important need for further research to be undertaken in this area.
- The review highlighted that different preparations, number of bacterial colony-forming units (CFUs), species type, timecourse and study objectives makes it difficult to determine fundamental conclusions on the efficacy of probiotics.
- That said, papers reviewed indicated the potential for a 55% increase in anti-inflammatory cytokines, reduced prevalence of URTIs, reduced Epstein-Barr and cytomegalovirus citrate antibodies, and improved recovery times.
- Probiotic supplementation likely enhances microbiota diversity and may indirectly support increased training load, and performance maintenance through immune defence. However, there were no indications that endurance performance was specifically enhanced.
Clinical practice applications:
- Most of the papers reviewed used formulae containing either Lactobacillus spp. (e.g. Plantarum, Acidophilus, Casei Shirota) or Bifidobacterium spp. (e.g. animalis subsp., bifidum, lactis, longum subsp.) or combinations. There was little mention of prebiotic or symbiotic strategies.
- Any impact of probiotics on exercise performance is likely to relate to both immune modulation and/or mechanisms leading to reduced muscle damage.
- Surprisingly, there was only partial mention of the use of probiotics for GI support and several notable papers were not included in the review. That said, the authors did note that with increased prevalence of exercise-induced gastrointestinal symptoms with endurance sport due to acute GI hypoperfusion and localised ischemia, acute probiotic strategies have resulted in reduced GI symptom frequency and severity in athletes.
- Importantly no adverse events following probiotic supplementation in endurance athletes were reported.
Considerations for future research:
- Clearly further research is warranted in terms of probiotic strain specific benefits both in training and in-race event effectiveness.
- The authors reported that there were no studies found on the effect of probiotics on hormonal or nervous systems in endurance athletes.
- Further research is needed to consider the impact of acute versus chronic probiotic use on intestinal metabolites, especially considering recent interactions between specific bacterial strains and short-chain fatty acid production being associated with performance (see: https://www.nutrition-evidence.com/article/31235964?term=31235964.
Abstract
BACKGROUND Probiotic supplements contain different strains of living microorganisms that promote the health of the host. These dietary supplements are increasingly being used by athletes to improve different aspects such as athletic performance, upper respiratory tract infections (URTIs), the immune system, oxidative stress, gastrointestinal (GI) problems, etc. This study aimed to identify the current evidence on the management of probiotics in endurance athletes and their relationship with sports performance. METHODS A systematic review of the last five years was carried out in PubMed, Scopus, Web of science, Sportdiscus and Embase databases. RESULTS Nine articles met the quality criteria. Of these, three reported direct benefits on sports performance. The remaining six articles found improvements in the reduction of oxidative stress, increased immune response and decreased incidence of URTIs. There is little scientific evidence on the direct relationship between the administration of probiotics in endurance athletes and sports performance. CONCLUSIONS Benefits were found that probiotics could indirectly influence sports performance by improving other parameters such as the immune system, response to URTIs and decreased oxidative stress, as well as the monitoring of scheduled workouts.