Effectiveness of Nitrate Intake on Recovery from Exercise-Related Fatigue: A Systematic Review

Abstract

Background: Recovery between efforts is critical to achieving optimal physical and sports performance. In this sense, many nutritional supplements that have been proven to improve recovery and physical and physiological performance are widely used. Supplements such as nitrates (NO3−), including organic foods such as beets, promote muscle recovery and relieve fatigue. This study aimed to comprehensively summarise the available literature on the effect of NO3− consumption on exercise-related fatigue and muscle damage. Methods: A systematic search was carried out based on the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) using electronic databases (e.g., PubMed, Scopus, and Web of Science). From a total of 1634 studies identified, 15 studies were included in this review. Results: Based on the review, NO3− intake provokes physiological and metabolic responses that could potentially boost exercise-related recovery. NO3− could improve recovery indicators related to strength, pain, inflammation, and muscle damage. Conclusions: Despite the relative proven effectiveness of NO3− on recovery after aerobic and anaerobic efforts, based on the heterogeneity of the procedures (e.g., dosage, chronic vs. acute intake, participants’ characteristics, variables and outcomes), it could be premature to suggest its extended use in sports.

Beet supplementation mitigates post-exercise inflammation

“…This is the first exercise-based human clinical trial to investigate the influence of BEET supplementation on inflammation using a human systems biology approach. Other similar studies used a few targeted outcomes, had widely disparate research designs, and generally reported null or minor effects of increased plasma NO 3 − + NO 2 − from nitrate supplementation on post-exercise inflammation biomarkers including cytokines ( 8 , 17–19 ). In one study with 34 runners, beetroot juice versus placebo supplementation for 3 days following a marathon race had no effect on muscle soreness, creatine kinase, interleukin (IL)-6, IL-8, tumor necrosis factor-α (TNFα), blood leukocyte cell counts, or C-reactive protein (CRP) ( 19 ).…”

“…The primary performance benefit of nitrate supplementation appears to be a reduction in the energy cost of exercise and a corresponding modest improvement in endurance capacity ( 5–7 ). Studies reporting performance benefits used acute nitrate doses of 5–6 mmol (or about 300 mg), or chronic doses at about half that amount ( 8 ). Chronic nitrate supplementation has not been consistently linked to improvements in aerobic capacity or performance ( 9 ).…”

“…However, most of the evidence comes from rodent-based studies. Human studies investigating the effects of nitrate or nitrate-rich beetroot juice on exercise-induced inflammation and muscle damage have produced mixed results ( 8 , 17–19 ). Part of the problem is that only a few basic outcome measures related to inflammation (e.g., C-reactive protein, IL-6, IL-8) have been utilized in these studies.…”

A Human-Adaptive Model for User Performance and Fatigue Evaluation during Gaze-Tracking Tasks

“…Thus, the proposed models are suitable for but not limited to the development of the PCS-based user interfaces. Fatigue in the field of sport training and physiology is widespread for researchers [91,92]. Both subjective and objective research methods are applied.…”

“…Furthermore, impulse-response models in the physiological domain elegantly include fatigue factor in mathematical performance models. Although a mathematical impulse-response model abstracts the human performance to two factors (fitness and fatigue), it has still been validated in many studies regarding the performance estimation of athletes [91,92].…”