How are diet and exercise related to gut microbiota and metabolites in bodybuilders?

How are diet and exercise related to gut microbiota and metabolites in bodybuilders?

A recently published study in Metabolites examined the microbiome dynamics of diet, exercise and gut in male bodybuilders.

Lernen: Schnittpunkt von Ernährung und Bewegung mit dem Darmmikrobiom und zirkulierenden Metaboliten bei männlichen Bodybuildern: Eine Pilotstudie. Bildnachweis: Goami/Shutterstock

background

The optimal exercise and nutrition regimens are elusive because exercise/nutrition interventions have produced varying results from person to person. This is seen in sports, where diets have been developed to supplement athletic performance and optimize energy availability. Nevertheless, individual factors determine the sporting results. Recently, there has been a growing interest in the role of the gut microbiota in individual athletic outcomes.

About studying

In the present study, researchers tested whether defined changes in diet and exercise are associated with changes in gut microbiota and metabolites in bodybuilders. Male participants aged 18 years or older preparing for a bodybuilding competition were eligible for inclusion.

Five bodybuilders with longitudinal blood and stool samples consistent with training and nutritional history were selected. They were on average 28 years old, 177 cm tall, weighed 77.7 kg and had 4.2 years of bodybuilding experience. Samples were obtained eight weeks (PRE8), one week (PRE1) before and four weeks (POST4) after the competition.

Participants abstained from alcohol, caffeine, and exercise for 12 hours before blood sampling. Hydrophilic metabolites were measured in a targeted metabolomics analysis using a liquid chromatography-mass spectrometry (LC-MS) system. Participants completed food and exercise diaries for a week prior to each assessment point.

Food, fluid, and supplement intake were documented in food diaries, while resistance and aerobic exercise were documented in training diaries. Body composition was estimated using a dual-energy X-ray absorptiometry (DXA) scanner. Stool samples were self-collected from participants within a week before each assessment time point. Total DNA was isolated from the stool samples. The V4 region of 16S ribosomal RNA (rRNA) was used for microbiome profiling.

Changes in physical activity and body composition at PRE1 and POST4 were compared to PRE8 as baseline. Differences in metabolite concentrations between time points were analyzed using the Kruskal-Wallis test. One sample from the PRE1 time point was excluded from analysis due to a failed LC-MS quality control check.

Results

All participants achieved the desired changes in body composition during the preparation period (PRE8 – PRE1). There was a greater decrease in fat mass than lean mass. Two participants were more successful at maintaining lean mass than others. One participant had the smallest (6.4%) fat mass reduction. All participants experienced an increase in fat and lean mass after the competition.

Exercise training was reduced compared to baseline at PRE8 and POST4 time points, but training schedules varied between individuals. The increase in aerobic and resistance training from PRE8 to PRE1 in only one participant reflected better lean mass preservation but did not correspond to fat mass reduction. Next, participants were assessed for dietary intake at – food, macronutrient and energy levels.

Energy intake was similar for all participants and was highest in four participants after the competition. Larger decreases in pre-competition energy intake (PRE8 to PRE1) corresponded with better reductions in fat mass, but not with changes in lean mass. The pre-competition protein contribution was above the upper limit of the acceptable macronutrient distribution range (AMDR), while the carbohydrate contribution was below the lower limit. Energy intake as fat was within AMDR limits.

The minimum recommended daily intake (MRDI) of protein was exceeded by the participants at all time points. Additionally, there was inter-individual variability in consumption of protein/amino acid supplements. Each participant had a unique and dynamic gut microbiota. There was no significant association between samples from different participants at a single time point.

After competition, a temporal shift in microbial diversity between and within sample(s) was observed. The microbial communities at the PRE8 and PRE1 time points of each individual were more similar than that of the POST4 sample community. Additionally, four individuals had low diversity within the sample at POST4.

Across all participants, most microbes (55% to 85%) were Firmicutes. Participants' serum metabolic profiles were evaluated in fasting and exercise-free states. Of the 127 metabolites, nine were found to be significant at time point. Participants had unique metabolite profiles throughout the assessment.

The POST4 metabolite profiles were different from the PRE8 or PRE1 profiles. Pre-competition metabolite profiles were characterized by higher levels of malonate, guanidinoacetic acid, acetylcarnitine, α-ketobutyrate and β-hydroxybutyrate. In contrast, post-competition profiles were characterized by increased saccharopine, choline and NAD+ levels.

Conclusions

Overall, all participants successfully reduced fat mass and maintained lean mass during the pre-competition period. Participants with the greatest decrease in food energy intake before the competition showed a greater decrease in fat mass. The microbial composition differed significantly between individuals. Despite interindividual differences in gut microbiome composition, microbial diversity within and between samples could be predictably nutritionally modulated.

The results suggest that predicting the dynamics between gut microbiome, metabolites, diet and exercise would be successful at the individual level rather than between individuals. Therefore, personalized exercise training and diets would be more beneficial than diet/exercise programs based on population-generated patterns.

Reference:

• Luk, A. et al. (2022) „Intersection of Diet and Exercise with the Darm Microbiome and Circulating Metabolites in Male Bodybuilders: A Pilot Study“, Metabolites, 12(10), p. 911. doi: 10.3390/metabo12100911. https://www.mdpi.com/2218-1989/12/10/911

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