Resistance exercise increases gastrointestinal symptoms, markers of gut 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. 2022 May 25. doi: 10.1249/MSS.0000000000002967. Epub ahead of print.
Males after resistance training subjectively and objectively show more signs of gastrointestinal stress and gut permeability than after resting for 45 minutes.
Exercise provides numerous health benefits; however, it can trigger gastrointestinal (GI) distress, at least in part because of reduced blood flow to the gut. 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 GI system would help clinicians develop strategies to reduce these side effects and optimize nutrient absorption.
Hart and colleagues completed a randomized, cross-over study of 30 (15 male, 15 female) resistance-trained participants to determine the influence of acute resistance training and biological sex on subjective GI distress, GI damage, and GI permeability.
The researchers enrolled 30 participants who participated in resistance training at least 3 times per week for at least one year before the study. They also had to be able to leg press at least 2 times their body weight. Participants completed a health and activity questionnaire and the Gastrointestinal Symptom Rating Scale to identify pre-existing GI conditions. The authors standardized each participant’s diet, physical activity, and hydration status to be consistent between the two sessions. The participants completed the experimental sessions 2 weeks apart and in random order. During the resistance training session, participants completed a standardized warm-up routine and an exercise protocol of squat, seated shoulder press, deadlift, bent-over row, and leg press exercises. They performed all exercises at 70% of the participants 1 rep max for 4 sets of 10 repetitions with standardized rest breaks. During the control session, participants completed all assessments but sat for 45 minutes. Before and after the experimental trials, participants completed the Gastrointestinal Symptom Rating Scale to assess GI symptoms. Blood samples were also taken following experimental sessions to assess biomarkers of GI distress.
Seventy percent of participants reported at least one GI symptom after resistance training, usually at least nausea (63%). Analysis of blood samples revealed that biomarkers for intestinal damage and gut permeability were highest after resistance exercise bout in males. Females had no differences in serum measures of gut damage or permeability after exercise or control sessions.
Interestingly, males who participated in resistance exercises had the highest risk for GI distress and permeability. Hence, they may also have an altered ability to absorb nutrients after resistance training. It would be interesting to see these results reproduced in a larger study and among people with different experience levels in resistance training.
Clinicians should recognize that a session of resistance training could cause GI symptoms and distress affecting nutrient intake/absorption. It may be beneficial to discuss with a nutritionist if an athlete needs changes to post-exercise food intake if they report greater GI symptoms after resistance training.
Questions for Discussion
Does this new finding help contextualize experiences you have had with patients? How might this impact your use or recommendation of resistance training?
Written by: Kyle Harris
Reviewed by: Jeffrey Driban