Gas and pain during exercise – Causes and solutions

Javier Colomer 5 min. of reading Fitness Leave a comment

Most of the digestive system problems related to exercise are directly related to intensity: if the intensity is low or moderate, it benefits gastric emptying, and the same goes for intestinal transit; but if the intensity is high, the opposite can happen.

Although rare, about 15% of athletes, especially endurance athletes, can present acid reflux into the oesophagus during exercise. The acid reflux occurs from a work intensity of 80% VO2max, approximately.

The acute physiological effects that occur from this intensity cause an exponential increase in acidosis caused by metabolites, such as hydrogen ions (H+), hypoxanthine or lactate. This alteration of the acid-base balance (decrease in pH) can cause a neuromuscular disorder of the lower two-thirds of the oesophagus (achalasia).

Under normal conditions, the pressure in the internal oesophageal sphincter is superior to the gastric, and during exercise, achalasia modifies (inverts) this normality.

Although it’s not easy to prove that aerophagy or fluid/food intake are directly related to it, it’s certain that the adrenal activity we’re in during high-intensity exercise causes a slowing of peristalsis and gastric emptying. This increases the risk of reflux and symptoms like pain in the lower part of the breastbone or burps.

Index

1 Other factors
2 Recovery of normality
3 Bibliographic Sources:
4 Links related to the subject:

Other factors

Apart from the exercise load itself (intensity, volume, frequency, density…) other factors should also be considered, including the exercise modality, the posture adopted, or even the intake of (certain) foods close to training (pre- and intra-training).

Exercise modality: running has proven to be one of the most reflux-inducing exercises, while the exercise bike is much safer in this regard, likely due to the lower mechanical vibration of the body. Nevertheless, weight lifters can report even greater reflux episodes than runners, especially in sessions where certain exercises are carried out; and this aspect is directly related to the following points.
Exercise position: Analysing different positions (upright, leaning and sitting), most people suffer from reflux in forward bending exercises, which compress the abdomen and increase intra-abdominal pressure.

The hypothesis behind this finding is that there must be an increase in lower oesophageal sphincter pressure as a protective response to an increase in intra-abdominal pressure.

This occurs in exercises such as leg raises from a supine position (the typical “lower abdominals” that many perform), or the deadlift, in which the core tilts + Valsalva manoeuvre to protect the lower back and keep the pressure gradient between the oesophagus and the stomach constant can generate reflux.

Foods

Some foods have also been shown to cause achalasia, so they should be avoided before exercising

This includes fats, starches, fibres, chocolate (specifically), excessive protein intake due to its nitrogenous structure, alcohol, carbonated drinks, and even certain types of carbohydrates (amylopectin).

Going further, certain ingredients present in pre-workouts and fat loss supplements, such as caffeine and/or theine, can irritate the lining of the oesophagus and favour these unpleasant symptoms.

Fasting or a light meal that promotes effective gastric emptying before a training session decreases the probability of reflux (high volumes of food predispose to reflux in the same way as the type of food does); as well as, during training, cyclodextrins and/or CH mixes of low osmolarity and low concentration (<60-80 g CH/L drink).

Recovery of normality

In acute cases of gastroesophageal reflux complaints, moderate to low-intensity exercise (<70% VO2max) has been shown to promote digestive function and intestinal transit, so walking or taking a short walk after completing the high-intensity exercise would be a solution to not having to suffer that acidity for the rest of the day.

Similarly, deep diaphragmatic breaths, drawing air into the abdomen, will facilitate a return to normal conditions, as the work of the respiratory muscles has been positively linked to metabolic clearance and restoration.

Bibliographic Sources:

Calderón, F.J. (2007). Fisiología aplicada al deporte. Madrid. Editorial Tébar.
Clark, C. S., Kraus, B. B., Sinclair, J., & Castell, D. O. (1989). Gastroesophageal reflux induced by exercise in healthy volunteers. JAMA, 261(24), 3599-3601.
Collings, K. L., Pierce, P. F., Rodriguez-Stanley, S., Bemben, M., & Miner, P. B. (2003). Esophageal reflux in conditioned runners, cyclists, and weightlifters. Medicine and science in sports and exercise, 35(5), 730-735.
Chicharro, J. L., & Vaquero, A. F. (2006). Fisiología del ejercicio. Madrid. Ed. Médica Panamericana.
Sodhi, J. S., Zargar, S. Javid, G., Khan, M. A., Khan, B. A., Yattoo, G. N., … & Shoukat, A. (2008). Effect of bending exercise on gastroesophageal reflux in symptomatic patients. Indian J Gastroenterol, 27(6), 227-231.

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