Table 2 Effect of exercise and/or athletic diet on the gut microbiota: Characteristics of included articles (by publication date)
Authors, year, country | Subjects characteristics | Study design and gut microbiome analysis | Diet and/or exercise | Duration | Key outcome(s) |
|---|---|---|---|---|---|
1. Clarke et al., 2014, Ireland [19] | Professional male rugby players, n = 40, 29 ± 4 years; Healthy matched controls, n = 46, 29 ± 6 years | Cross-sectional 16S rRNA gene amplification of the V4 region | Observational | Cross-sectional | • Athletes had a higher diversity of gut micro-organisms, representing 22 distinct phyla. • GMa diversity indices were positively correlated with protein intake and serum creatine kinase in athletes. |
2. Estaki et al., 2016, Canada [14] | Healthy young males and females, n = 39, stratified by cardiorespiratory fitness, Low: 25.5 ± 3.3 years; Average: 24.3 ± 3.7 years; High: 26.2 ± 5.5 years | Cross-sectional 16S rRNA gene amplification of the V3 and V4 regions | Observational | Cross-sectional | • VO2peakb, independent of diet, positively correlated with increased GM diversity. • VO2peak explained significant variation in GM predicted metagenomic functions, aligning positively with genes related to bacterial chemotaxis, motility, and fatty acid biosynthesis. • Increased production of fecal butyrate abundances of butyrate-producing taxa (Clostridiales, Roseburia, Lachnospiraceae, and Erysipelotrichaceae) amongst physically fit participants. |
3. Yang et al., 2017, Finland [94] | Premenopausal females with low, moderate and high-cardiorespiratory fitness (VO2max), n = 71, Low VO2max: 40.4 ± 3.5 years; Moderate VO2max: 39.7 ± 4.2 years; High VO2max: 30.6 ± 5 years | Cross-sectional 16S rRNA hybridization, DNA-staining, and flow cytometry | Observational | Cross-sectional | • Decreased Bacteroides, increased Eubacterium rectale-Clostridium coccoides in low VO2max participants vs high VO2max participants. • VO2max inversely associated with Eubacterium rectale-C. coccoides but not with other bacteria. |
4. Allen et al., 2018, USA [98] | Sedentary lean males and females, n = 18, 25.1 ± 6.52 years; Obese males and females, n = 14, 31.14 ± 8.57 years | Longitudinal design 16S rRNA gene amplification of the V4 region | 30–60 min moderate-to-vigorous intensity (60–75% of HRRc) aerobic exercise, 3x per week | 6 weeks | • Exercise induced shifts in SCFAd-producing taxa (Faecalibacterium and Lachnospira species) and genetic machinery (BCoATe) were more substantial in lean versus obese participants. • A return to sedentary activity for 6 weeks led to a BMIf-dependent reversion in gut microbiome composition. |
5. Barton et al., 2018, Ireland [13] | Professional male rugby players, n = 40, 29 ± 4 years; Healthy matched controls, n = 46, 29 ± 6 years | Cross-sectional Metagenomic whole genome shotgun sequencing and urine and fecal metabolomics | Observational | Cross-sectional | • Relative increase in pathways (amino acid and antibiotic biosynthesis and carbohydrate metabolism) in athletes vs control. • Increase in fecal metabolites (acetate, propionate and butyrate) in athletes vs control. |
6. Cronin et al., 2018, Ireland [199] | Sedentary overweight/obese males and females, n = 90, 18–40 years | Randomized controlled trial, parallel group design Metagenomic whole genome shotgun sequencing and urine and fecal metabolomics | Groups: • Protein-only; 30 g protein (24 g whey) • Exercise-only; Combined aerobic and resistance training (aerobic training of moderate intensity and resistance training of 3 sets of 8 repetitions on 7 different resistance machines) 3 x per week • Exercise + protein | 8 weeks | • Increase in alpha diversity in Exercise + Protein group vs Protein group. • Decrease in beta diversity of the gut virome in participants consuming protein. |
7. Moreno-Pérez et al., 2018, Spain [196] | Endurance-trained males, n = 18, 35.38 ± 9.0 years (control group), 34.90 ± 9.49 years (protein group) | Randomized controlled trial, parallel group design 16S rRNA gene amplification of the V3 and V4 regions | Groups: • Control: maltodextrin • Protein: blend of whey isolate (10 g) and beef hydrolysate (10 g) Minimum training frequency of 5 endurance training sessions per week; ≥240 min per week | 10 weeks | • Increase in Bacteroidetes in protein group. • Decrease in Roseburia, Blautia, and Bifidobacterium longum in protein group. |
8. Taniguchi et al., 2018, Japan [101] | Healthy elderly Japanese males, n = 33, 62–76 years | Randomized crossover trial 16S rRNA gene amplification of the V3 and V4 regions | 5-week control period OR 5-week supervised, progressive aerobic exercise program. Cycle ergometer 3x per week. 60% of pre exercise VO2peak during week 1, 70% during weeks 2 and 3, and 75% during weeks 4 and 5. Duration was 30 min for weeks 1 and 2, and 45 min for weeks 3–5. | 5 weeks | • Short-term endurance exercise did not appreciably influence diversity and composition of gut microbiota. Minor changes in the gut microbiota were associated with cardiometabolic risk factors. • Decreased relative abundance of C. difficile significantly decreased, whereas Oscillospira significantly increased during exercise as compared to the control period. |
9. Durk et al., 2019, USA [93] | Healthy young males and females, n = 37, 25.7 ± 2.2 years | Cross-sectional Quantitative Polymerase Chain Reaction (qPCR) that specifically measured the quantity of a target gene (16 s RNA) found in Firmicutes and Bacteroidetes | Observational | Cross-sectional | • Firmicutes/Bacteroidetes ratio positively correlated to VO2max. • VO2max explained ~ 22% of the variance of an individual’s relative gut bacteria as determined by Firmicutes/Bacteroidetes ratio. |
10. Keohane et al., 2019, Ireland [99] | Ultra-endurance male athletes, n = 4, 26.5 ± 1.3 years | A prospective, repeated-measures, within-subject report Metagenomic whole genome shotgun sequencing | Observational | 33-day event; 3-month follow-up | • Increased alpha diversity throughout event. • Increased abundance of butyrate producing species (Roseburia hominis and members of the genus Subdoligranulum) and species associated with improved metabolic health (Dorea longicatena). • Many of the adaptions in GM community structure and metaproteomics persisted at 3 months follow up. |
11. Kern et al., 2019, Denmark [108] | Overweight/obese males and females; n = 88; 20–45 years | Randomized controlled trial, parallel group design 16S rRNA gene amplification of the V4 region | Exercise groups: • Habitual living (CON), • Active commuting by bike (BIKE) • Leisure-time exercise of moderate intensity (MOD) • Vigorous intensity exercise (VIG) | 6 months | • Increase alpha diversity index in VIG at 3 months compared with CON. • Beta diversity changed in all exercise groups compared with CON; VIG decreased heterogeneity. • Increased inferred functional potential of microbiota in the exercise groups, primarily at 3 months and in MOD. |
12. Morita et al., 2019, Japan [103] | Healthy sedentary elderly females; n = 32; ≥ 65 years | Non-randomized comparative trial 16S rRNA terminal restriction fragment length polymorphism analyses | Exercise groups: • Trunk muscle training group 1 h per week. • Aerobic exercise training group, brisk walking at ≥3 METSg, 1 h daily. | 12 weeks | • Increased Bacteroides relative abundance in aerobic exercise group. • Increased Bacteroides following exercise intervention associated with increased 6-min walk test. |
13. Motiani et al., 2019, Finland [109] | Obese sedentary, prediabetic/type 2 diabetic males and females; n = 26 (n = 9, n = 17 respectfully); 49 ± 4 years | Parallel group design 16S rRNA gene amplification of the V3 and V4 regions | Exercise groups: • Sprint interval training group; 30 s exercise bouts (4–6) of all out cycling efforts with 4 min of recovery, 3x a week. • Moderate intensity continuous training group; 40–60 min cycling at 60% of VO2peak intensity, 3x a week. | 2 weeks | • Increased Bacteroidetes in both groups. • Decreased Firmicutes:Bacteroidetes ratio in both groups. • Decreased Clostridium genus and Blautia. • Colonic glucose uptake positively associated with Bacteroidetes and inversely with Firmicutes phylum, Firmicutes: Bacteroidetes ratio and Blautia genus. |
14. Murtaza et al., 2019, Australia [230] | Elite male endurance race walkers; n = 21; 20–35 years | Non-randomized comparative trial 16S rRNA gene amplification of the V6-V8 regions | Diet groups: • High-Carbohydrate • Periodized Carbohydrate • ketogenic LCHFh Consumed during an intensified training program. | 3 weeks | • Microbiota profiles at baseline could be separated by Prevotella or Bacteroides dominated enterotype. • LCHF diet resulted in increased relative abundance of Bacteroides and Dorea and decreased Faecalibacterium. • Negative correlations between Bacteroides and fat oxidation, and between Dorea and economy test following LCHF intervention. |
15. Scheiman et al., 2019, USA [16] | Experiment 1: • Athletes from the 2015 Boston Marathon (n = 15), sedentary controls (n = 10) Experiment 2: • Ultramarathoners and Olympic trial rowers (n = 87) | Observational 16S rRNA gene amplification of the V4 region for experiment 1 Metagenomic whole genome shotgun sequencing for experiment 2 | Experiment 1: • Marathon event Experiment 2: • Exercise bout | Experiment 1: • Fecal samples collected 7 days before and after Marathon event Experiment 2: • Pre/post exercise | Experiment 1: • Increased Veillonella relative abundance in marathon runners post marathon. • Veillonella was more prevalent among runner’s vs non-runners, although this was not statistically significant. Experiment 2: • Increased Veillonella abundance post exercise. • Veillonella methylmalonyl-CoA pathway was overrepresented in athlete metagenomic samples post exercise. |
16. Liu et al., 2019, China [106] | Overweight/obese prediabetic males; n = 39; 20–60 years | Randomized controlled trial, parallel group design Metagenomic whole genome shotgun sequencing and fecal metabolomics | Groups: • Control; No exercise. • High-intensity exercise; 70 min combined aerobic and resistance interval training, 3x a week. | 12 weeks | • Microbiota profiles were differentially altered in exercise responders (n = 14) vs non-responders (n = 6). • The microbiome of responders had increased functional capacity for SCFA biosynthesis and BCAAi catabolism. • Exercise-induced gut microbiota changes were positively correlated with improvements in glucose homeostasis and insulin sensitivity. • Baseline microbiome features accurately predicted personalized exercise responses. • Fecal microbiota transplantation from responders conferred the metabolic benefits of exercise in mice. |