Is endurance exercise good for your gut?




Physical exercise can be beneficial or harmful for the gastrointestinal (GI) tract in a dose-effect relationship based on intensity and duration.

Mild-to-moderately intense exercises plays a protective role against colon cancer, diverticular disease, gallstones and constipation, whereas ongoing or even acute bouts of  strenuous exercise may provoke heartburn, nausea, vomiting, abdominal pain, diarrhea, “leaky gut”, food allergies and even GI bleeding.

One-quarter to one-half of elite athletes are affected by GI symptoms that may deter them from participating in training and competitive events.

Some recommendations that can help prevent or mitigate exercise-induced GI symptoms include: changing lifestyle, training and meal routines, ensuring adequate hydration, and being sure to avoid excessive use of some medications.

Training and Avoiding Over-Training

A cardiorespiratory workout should consist of:

  1. Warm-up
  2. Workout
  3. Cool-down


A warm-up prepares the body for activity by increasing heart and respiratory rates, tissue temperature and mental readiness.  A general warm-up consists of low intensity, non-specific movements. A specific warm-up consists of low intensity movements that mimic the exercise to follow.


A 15 minute sample warm-up would include:


  1. Myofascial compression techniques that address over-active muscles. The ultimate six for runners would include the: soleus, quadriceps, psoas, pirirformis, pectoralis and thoracic spine.
  2. Active-isolated stretching
  3. Running  in Zone 1 for the first 10 minutes of the workout


An endurance workout should consist of Stage/Zone training (% based on maximum predicted heart rate: 220 minus your age = max heart rate):

Zone 1- 65-75%

Zone 2- 80-85%

Zone 3- 86-90%

Zone 1 is a good intensity to start the workout. It is also the “recovery zone.”

Zone 2 training helps to increase one’s anaerobic threshold and is appropriate for individuals who have progressed in their training.

Zone 3 is considered high intensity and is used to prevent plateaus in training as well as to enhance fitness. For most people exercising in Zone 3, once per week is enough. Beyond that, over-training can result, leading to digestive and other health issues.

Training for an event should incorporate planned changes (periodization). These changes reduce the risk of over-training and ensure optimal progress toward a goal (e.g. an event).

An essential part of any program also depends on rest and recovery (i.e. sleep and nutrition).

I’ve got a gut feeling that you are over-training…

General symptoms of over-training:

  • Fatigue
  • Aches and pains
  • Pain in muscles and joints
  • Sudden drop in performance
  • Insomnia
  • Headaches
  • Decreased immunity (increased number of colds, sore throats)
  • Decrease in training capacity/intensity
  • Moodiness, irritability and depression
  • Loss of enthusiasm for the sport
  • Decreased appetite
  • Decreased sex drive
  • Increased incidence of injuries

Over-training and the gut

Exercise is a stressor. It activates the hypothalamic-pituitary-adrenal axis leading to a host of hormonal adjustments.

Cortisol is a key hormone regulator, which is tightly tied to both the intensity and duration of an endurance activity. It influences gut and immune function through secretory IgA , which maintains gut integrity.

Prolonged stress with elevated cortisol is known to lower secretory IgA, leaving the gut and respiratory tract susceptible to infections.

Exercise and Food Allergy

Exercise is believed to increase small bowel permeability in susceptible individuals.

Food-exercise induced allergic-type reactions are mediated by increased gut permeability.  Exercise increases intestinal absorption of potential allergens in both normal and reactive individuals.

This is essential knowledge to have when evaluating exercise programs in those athletes with digestive complaints suggestive of food sensitivity or allergy, especially given that athletes often consume gluten containing grains and dairy products.

Gluten containing grains are an easy food to help replenish glycogen stores, but are unfortunately common culprits of exercise induced digestive issues in addition to other health problems discussed in prior posts.

The Paleo Solution for Endurance Athletes

We are genetically adapted to a hunter gatherer diet.  The introduction of domesticated animals, agriculture, and processed foods are very recent developments in the scope of evolutionary history.  As such, our bodies are not adapted to a diet derived from these technological developments and consequently diets that emphasize these processed foods (e.g. sugar, grain and dairy) have resulted in most of the chronic disease that plague are society.

 General Paleo Guidelines:

1. Eat plenty of lean meats (fish, poultry, lean beef, wild game)

2. Eat plenty of fruits and vegetables

3. Avoid dairy

4. Avoid starches and sugars (breads, grains, etc)

5. Avoid processed foods.


While we are genetically suited for this diet, our ancient ancestors seldom did 2 hour runs and 6 hour bikes.  More than likely they had periods of intense activity, but these where relatively brief and spaced apart. A strict paleo diet is not well-suited to the needs of endurance athletes to fuel optimum performance and recovery, so the activity can be repeated after a relatively short time.

Modifications to the Paleo diet for Endurance Athletes

1. Majority of nutrition from fruits, lean protein and fresh veggies.

2. Starch and sugar only during and after training.

3. Eliminate as much processed food as possible.

 Adding, Starch and sugar only during and after training satisfies the need to quickly replace glycogen stores after exercise.  This ensures the athlete is ready to repeat the activity within a relatively short time and minimizes the adverse effects that these foods can have on gut health when over consumed.

Is Endurance Exercise good for your Gut? In moderation yes, but why do this type of activity? If it’s for a charitable fund raiser, that’s one thing, but if it’s for the pursuit of health or weight loss, research points to resistance and interval training as more effective means.





About the Author

Dr. Geoff LecovinNaturopathic Physician/Chiropractor/Acupuncturist/Certified Strength and Conditioning Specialist/Corrective Exercise Specialist/Performance Enhancement Specialist/Certified Sports Nutritionist/View all posts by Dr. Geoff Lecovin