Probiotics and their benefits for recreational runners’ performance, body composition and quality of life.
A double-blind controlled trial demonstrated the positive effects of probiotic supplementation on performance, body composition and quality of life in recreational runners.
The runner’s enemy: the gut
Physical activity has many benefits for the body, but it can also put a strain on the gastrointestinal system..
Several studies claim that 70% of runners who train intensively experience intestinal problems: abdominal pain, gurgling, diarrhoea, during or after running.
The cause seems to be running itself: the movement of food in the stomach, the reduced blood flow to the intestines and the lowered intestinal defences leave the field open for bacteria to cause problems.
The runner’s diet can also affect the proper functioning of the gut. A diet high in protein and low in carbohydrates, the use of protein supplements and sports drinks all contribute to an increased risk of intestinal problems. Conversely, reduced fibre intake can lead to the opposite problem, constipation.
Studies suggest that regular consumption of probiotics – the good bacteria commonly found in fermented foods – can strengthen the gut lining and reduce inflammation throughout the body. This limits damage to the gastrointestinal system and causes fewer problems during exercise.
The study
A study published in the Journal of Exercise Science & Fitness examined the gut health of nineteen healthy and active runners. Fifteen men and four women, with an average age of 29.11 years, volunteered for this double-blind, controlled study.
Participants were divided into two groups based on their performance on the 12-minute Cooper’s Run Test (CRT):
- One group took a probiotic supplement containing Lactobacillus acidophilus and Bifidobacterium longum for five weeks;
- The other group took a placebo containing only maltodextrin.
Before and after the intervention, all participants were assessed for CRT, emotional stability and gastrointestinal symptoms, gut microbiota composition, body composition and magnetic resonance imaging (MRI) indicators of skeletal muscle microcirculation.
Benefits of supplementing with probiotics
At the end of the analysis period, the group of runners who had taken probiotics experienced an overall improvement in their health status. A significant increase in the CRT score, a clear improvement in gastrointestinal symptoms with a significant reduction in constipation, and an impact on quality of life were highlighted.
The same indicators remained unchanged in the control group. There was a significant group-time interaction effect on gastrointestinal symptoms.
In addition, some indicators of the MRI metabolic cycle of skeletal thigh muscle also changed for the better in the probiotic group.
In terms of microbiota abundance, the probiotic group showed a significant increase in the abundance of beneficial bacteria and a significant decrease in the abundance of harmful bacteria, as expected.
Clinical significance
For runners who train intensively, probiotics can therefore improve athletic performance by optimising the balance of the gut microbiota, alleviating gastrointestinal symptoms and keeping the gut ‘safe‘.
However, much can also be done by the athlete’s diet, which must be balanced and not put stress on the gut.
