The Relationship between Physical Activity, Physical Exercise, and Human Gut Microbiota in Healthy and Unhealthy Subjects: A Systematic Review

Abstract

Several studies have been conducted to find at least an association between physical activity (PA)/ physical exercise (PE) and the possibility to modulate the gut microbiome (GM). However, the specific effects produced on the human GM by different types of PA/PE, different training modalities, and their age-related effects are not yet fully understood. Therefore, this systematic review aims to evaluate and summarize the current scientific evidence investigating the bi-directional relationship between PA/PE and the human GM, with a specific focus on the different types/variables of PA/PE and age-related effects, in healthy and unhealthy people. A systematic search was conducted across four databases (Web of Science, Medline (PubMed), Google Scholar, and Cochrane Library). Information was extracted using the populations, exposure, intervention, comparison, outcomes (PICOS) format. The Oxford Quality Scoring System Scale, the Risk of Bias in Non-Randomized Studies of Interventions (ROBINS-I) tool, and the JBI Critical Appraisal Checklist for Analytical Cross-Sectional Studies were used as a qualitative measure of the review. The protocol was registered in PROSPERO (code: CRD42022302725). The following data items were extracted: author, year of publication, study design, number and age of participants, type of PA/PE carried out, protocol/workload and diet assessment, duration of intervention, measurement tools used, and main outcomes. Two team authors reviewed 694 abstracts for inclusion and at the end of the screening process, only 76 full texts were analyzed. Lastly, only 25 research articles met the eligibility criteria. The synthesis of these findings suggests that GM diversity is associated with aerobic exercise contrary to resistance training; abundance of Prevotella genus seems to be correlated with training duration; no significant change in GM richness and diversity are detected when exercising according to the minimum dose recommended by the World Health Organizations; intense and prolonged PE can induce a higher abundance of pro-inflammatory bacteria; PA does not lead to significant GM α/β-diversity in elderly people (60+ years). The heterogeneity of the training parameters used in the studies, diet control, and different sequencing methods are the main confounders. Thus, this systematic review can provide an in-depth overview of the relationship between PA/PE and the human intestinal microbiota and, at the same time, provide indications from the athletic and health perspective.

Effect of Intensity and Duration of Exercise on Gut Microbiota in Humans: A Systematic Review

“…Ultramarathoners and triathlon athletes have shown an increase in several proinflammatory cytokines and proteins [ 54 ]. The analyzed studies have shown a pro-inflammatory status related to intestinal microbiota, similar to the recent systematic review that states that exercise duration could be related to a higher pro-inflammatory bacteria abundance [ 50 , 55 , 56 ].…”

“…A recent systematic review has found that Prevotella relative abundance looks to be associated with training duration [ 50 ]. In our systematic review, we found a similar result with a high Prevotella abundance associated with time-reported exercising during an average week.…”

How Diet and Physical Activity Modulate Gut Microbiota: Evidence, and Perspectives

“…Some papers have recently shown that physical activity is a potential factor favouring the biodiversity of the intestinal microbial ecosystem both in qualitative and quantitative terms, suggesting that the beneficial effects of physical exercise on gastrointestinal function, mood, and other brain functions, could be mediated by modifications of the microbiota. Unfortunately, the mode of action by which physical activity determines these changes is not yet clear; probably, it includes various interrelated factors and pathways, such as (i) changes in the bile acids profile which could exert antimicrobial activity and/or select certain bacterial species; (ii) increased production of immunoglobulins A (IgA) linked to the resistance to colonisation by specific microorganisms, (iii) increased production of SCFA, (iv) suppression of Toll-like receptor 4 (TLR4) signaling pathways, which can reduce serum lipopolysaccharides (LPS) levels; (v) release of myokines from muscle fiber cells, (vi) improvement of body composition, (vii) maintenance of glycemic homeostasis, (viii) reduction of intestinal transit time, and (ix) activation of the hypothalamic-pituitary-adrenal HPA axis and successive production of hormones caused by physical stress [65].…”

Physical activity induced alterations of gut microbiota in humans: a systematic review

“…From our practice we know that it is very hard to assemble a research group of high amounts of highly trained athletes, that's why we decided to accept all manuscript and supplements the knowledge from previous reviews on this topic, in particular general physical activity. Among published reviews Aya et al [14] in the systematic review focused on cross-sectional studies, Dorelli et al [15] used study designs with a control group that was measured only by the 16S rRNA method, Mitchel et al [16] collected data from rodents, large animals and humans, Ortiz-Alvares et al [17] concentrated on different length of exercise periods, Shahar et al [18] paid attention to interventions that last at last five weeks, Zheng et al [19] condensed knowledge about the influence of exercise on obesity and type 2 diabetes, Cataldi et al [20] excluded works without control groups, Clark et al [21] focused on the gut-brain axis, whereas Clemente et al [22] collected data about aerobic or aerobic combined with resistant training only. Therefore, knowledge gained in this review will enrich the current knowledge about the consequences of various physical activities on gut microbiota.…”