Going to the gym affects you in more ways than one

Resistance exercise increases gastrointestinal symptoms, markers of intestinal permeability, and damage in resistance-trained adults.

Hart TL, Townsend JR, Grady NJ, Johnson KD, Littlefield LA, Vergne MJ, Fundaro G. Med Sci Sports Exerc. May 25, 2022. doi: 10.1249/MSS.0000000000002967. E-publishing prior to printing.

https://pubmed.ncbi.nlm.nih.gov/35612399/

Take home message

Men subjectively and objectively show more signs of gastrointestinal stress and intestinal permeability after resistance training than after 45 minutes of rest.

Background

Exercise offers numerous health benefits; however, it can cause gastrointestinal upset, at least in part due to the reduced blood flow to the intestines. Most research in this area has focused on endurance athletes. We know much less about resistance training. Understanding the impact of resistance training on the gastrointestinal system would help physicians develop strategies to reduce these side effects and optimize nutrient absorption.

Study aim

Hart and colleagues completed a randomized, crossover study of 30 (15 male, 15 female) resistance-trained participants to determine the influence of acute resistance training and biological sex on subjective gastrointestinal symptoms, gastrointestinal damage, and gastrointestinal permeability.

Methods

The researchers enrolled 30 participants who participated in resistance training at least three times a week for at least a year before the study. They also had to be able to do leg presses of at least twice their body weight. Participants completed a health and activity questionnaire and the Gastrointestinal Symptom Rating Scale to identify pre-existing gastrointestinal conditions. The authors standardized each participant’s diet, physical activity, and hydration status to be consistent between the two sessions. Participants completed the experimental sessions two weeks apart and in random order. During the resistance training, participants completed a standardized warm-up routine and exercise protocol of squat, seated shoulder press, deadlift, bend-over row and leg press exercises. They performed all exercises on 70% of the participants, a maximum of 1 repetition for 4 sets of 10 repetitions with standardized rest breaks. During the control session, participants completed all assessments but remained seated for 45 minutes. Before and after the experimental studies, participants completed the Gastrointestinal Symptom Rating Scale to assess GI symptoms. Blood samples were also taken after experimental sessions to assess biomarkers of gastrointestinal complaints.

Results

Seventy percent of participants reported at least one gastrointestinal symptom after strength training, most commonly at least nausea (63%). Analysis of blood samples showed that biomarkers of intestinal damage and intestinal permeability were highest after strength training in men. Females had no differences in serum measures of intestinal damage or permeability after exercise or control sessions.

Viewpoints

Interestingly, men who participated in resistance exercises had the greatest risk of gastrointestinal problems and permeability. Therefore, they may also have an altered ability to absorb nutrients after resistance training. It would be interesting to reproduce these results in a larger study and among people with different levels of experience in resistance training.

Clinical implications

Clinicians should recognize that a session of resistance training can cause gastrointestinal symptoms and complaints that affect nutrient intake/absorption. It may be helpful to discuss with a nutritionist whether an athlete needs changes in food intake after exercise if he or she reports greater gastrointestinal symptoms after strength training.

Questions for discussion

Does this new finding help contextualize experiences you’ve had with patients? How might this affect your use or recommendation of resistance training?

Written by: Kyle Harris
Review by: Jeffrey Driban

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