Research Review: The relationship between exercise, inflammation, and respiratory immunity

The relationship between exercise and the immune systems is intensely complex with many moving variables. Exercise generally improves the immune system. The more exercise done, and the more regularly, the more the immune system is boosted. However, there is always a tipping point. Athletes are often pushed into longer bouts of exercise, and/or more intense training. This goes as well for some “general exercisers” who don’t consider themselves “athletes,” but will grind out intense workouts that are on par for athletes. I have seen this with recreational marathon runners, obstacle course racers, and people going “all in” for 30-, 60-, or 90-day challenges with their gyms or trainers. They may not think of themselves as “athletes,” yet they are putting in long hours and hard sessions, sometimes multiple workouts per day. Anyone working out intensely for over 45 minutes, more than 4 times a week, I would argue should call themselves at least “recreational athletes.”

In addition to increases in bodily pains and risk of injury, it’s not uncommon to see upper respiratory illnesses (URIs, ie: coughing, congestion, sinus drainage) and upper respiratory tract infections (URTIs, ie: common cold and influenza) in recreational and elite athletes.  In fact, URTIs are suggested to be the most common type of infection in the athletic population. But if exercise boosts the immune system, why is this happening?

Some exercise is good.

Indeed, some movement is good. Quality and consistent movement is great. Studies show that “moderately active” living poses greater resistance to pathogens by boosting the immune system surveillance of the body. “Moderate exercise” is somewhat subjective, but tends to range around 30 minutes of movement at 60-75% intensity, 4-6 days a week.

Animal studies showed that exercising for 20-30 minutes right before being exposed to a virus decreased morbidity and mortality from it, even if it was just a single session of exercise and the mouse had been sedentary outside of that bout. That lead to suggestions that exercising before traveling on an airplane, or going into other high-crowd areas, could help prevent illness.

Now, extend that exercise from a single session to a routine: research that looked at 12-15 weeks of moderate exercise saw that incidence and duration of URTIs was significantly lowered compared to sedentary individuals. Longer duration of the routine meant better adaptations in the immune system.

Acute Exercise, or just getting started

Some of you have heard me say over and over that “stress causes inflammation and health problems” and expand that ‘stress’ can mean emotional, mental, chemical, or physical. In this case, we’re looking at the physical stress of exercise, which also elevates cortisol (chemical stress.) You are tearing muscles, straining lungs, and working your heart. As many people who have “fallen off the wagon” of exercise can attest, getting back into the workout routine is the most physically painful part, compared to a few weeks in after your body has adapted. This is called the “General Adaptation Syndrome” (GAS) where the body isn’t used to the physical stress. Every exercise stress applied results in specific biochemical, neurological, and mechanical adaptions in the body. The first 2-3 weeks of this are called the “Alarm Phase” or “Shock Phase”, and typically muscle and joint pain, fatigue, and discomfort are all more extreme at this time.

Training load or volume alone does not give full information on the level of stress that an athlete (and their immune system) is under. Indeed, the way training in distributed or periodized is of key important also. Periodization is breaking down a training plan into smaller, progressive stages to build safely over several weeks or months. Rapid changes in training load (i.e., increasing too quickly) was a better predictor of URI risk than total load alone. This shows that it’s not just the amount of training, but jumping in too quickly can be detrimental to the immune system.

This is different than someone who has adapted to longer or more intense levels of exercise over time. Much like their bodies are adapted to recover faster between training sessions, the immune system also learned to rebound more rapidly.

Can it be too much?

That tipping point of “too much” strenuous and/or prolonged bouts of exercise can temporarily reduce the immune system (“exercise-induced immunodepression”) for a few hours to a few days, depending on the nature of the exercise and the health status of the person, as well as the rest time before the next round of exercise. This immunodepressed state is the time the individual is at higher risk of contracting a URI or URTI.

The less adapted to high frequency/intensity/duration of training, the higher the stress levels spike, and the lower the immune system plummets after. What goes up, must come down. But in time, you can taper the peak and the drop.

After Intense, Acute Exercise

How many people have had the experience of going through a prolonged period of intense stress (semester at school, large work projects, extended home situation) and when this intense period finally eases up, they get sick? It’s like the immune system fires on all cylinders to help get you through the stressful time, and then it rests when you do. Likewise, this can be seen in athletes.

A research review by Walsh et al. suggested that athletes most often would report URTIs either during the high-intensity and tapering period prior to competition (e.g., swimming, team sports) or in the period following competition (e.g., long distance running). Essentially, the times of illness were more common during the high intensity period (high stress and inflammation in the body), or about 1-2 weeks after as the body gets to rest (incubation period.)

Nieman et al reviewed marathon runners and respiratory illness. “Taking into account other factors influencing risk of URI (age, stress levels, and illness at home), the likelihood of URI was doubled in those who ran >96 km compared to those who ran 32 km as part of their weekly training programmes leading up to the event.”

It is interesting to note, as well, that some studies then went on to break down infectious versus non-infectious URIs. Meaning, sometimes the URI or URTI is based on a pathogenic infection (ie: bacteria, virus), and other times there is some other reason for feeling sick that didn’t have to do with a microbe. Reports show it can be due to inhaled pollutants or allergies, chlorine vapors for swimmers, cold and dry air; age; sleep quality; and more. These factors are less related to the immune system directly than they are related to inflammation. Once again, lifestyle factors pop up as important keys for staying healthy and keeping optimal respiratory functions. Keeping inflammation low before exercising may help reduce the over-inflammatory state brought on by intense exercise, and protect respiratory health.

So… What is the “Goldilocks” level? Not too little, but not too much too fast.
The J-Curve versus the S-Curve

The J-curve model suggests that an individual involved in regular moderate exercise is less likely to contract a URTI compared to a sedentary individual, but prolonged high-intensity exercise or periods of strenuous exercise training are associated with an above-average risk of a URTI. Like so:

The J-curves are the bold purple and red lines, showing that infection risk is average with a sedentary life. Then the immune system gets a boost, thus reducing infection risk, as a person moves into active or moderate exercise. But following that curve then leads to a split in research. At first, heavy or prolonged training seems to have a rebound effect, causing infection risk to go above average – but not always!

It seems that some athletes can reach “elite” status, and as their body adapts to these bouts of exercise, the curve instead moves into an S-curve and infection risk normalizes again, and the immune system can recover, coming back to average as the athlete-in-training adapts.

Lifestyle and the Elite Athlete

There have been some that suggest a prerequisite to achieving “elite” athlete status is an immune system which can withstand the strenuous nature of training and competition. Essentially, one cannot push to elite levels of training if the immune system cannot keep up.

And as past articles and posts have shown, there are ways you can help enhance your immune system through lifestyle, diet, and supplements.

Again, let’s think about that Alarm Phase. If the body is not used to the intense exercise, there is more inflammation and damage to the muscle fibers and tissues. Elite athletes, however, are trained better for this stress on the body. Likewise, elite athletes are usually tackling many aspects of their lifestyle to optimize their performance: sleeping well; properly fueling before, during, and after workouts; keeping a focused mindset; drinking plenty of water; stretching and recovering. They often tap into additional resources for support: keeping up on the latest in sport science, seeking out medical professionals, getting advice from nutrition professionals, working with trainers, and more. Genes may play a role, but this support team shows that managing other aspects is important and can help in prevention.

In the complexity of the immune system, the research does note that humans have demonstrated lower resistance to URTI when there is weakness or problems with other life stressors such as dietary deficiencies, psychological stress, sleep disturbance. In fact, the presence of nearly any of these other risk factors will cause a weaker immune response, and increase the risk of illness following prolonged exercise.

Lifestyle matters.

Could these lifestyle behaviors be another layer of protection for athletes and people looking to begin exercising, or boost their current training? Absolutely.


Athletes and individuals involved in heavy training programs and/or prolonged bouts of exercise appear to have an increased risk of contracting URIs. This is likely related to regular acute (and possibly chronic) periods of exercise-induced immunodepression. Regular moderate exercise, on the other hand, appears to have the opposite effect and reduces infection risk. So if you are looking to boost your training, pair gradual increases in exercise with healthy lifestyle habits to keep your infection risk as low as possible.


  • Move at least 30 minutes, 4-6 times per week. If you want to go above that, do so mindfully. There are benefits, but you want to give your body time to rest and adapt to an increased load. It is tempting for some who are finally getting their new quarantine routines down to want to double up workouts, or go for longer runs than they normally have time for. Be mindful, and gradually work your way up. This will reduce your risk of injury and illness.
  • Be sure to warm up and cool down appropriately.
  • Recover well. Stretch and foam roll. Rest and sleep to give your body enough time to recover between bouts of exercise.
  • Learn about proper form, get proper shoes, and ensure all other ergonomic aspects of exercise are optimized to reduce physical stress and injury.
  • Work with a trainer who knows how to periodize properly and can create workout plans that challenge you without shocking your system
  • Get a quality 7-8 hours of sleep each night
  • Fuel properly before, during, and after workouts to enhance the workout efforts as well as maximize post-workout recovery.
  • Nourish your body throughout the rest of the day as well to feed your cells with antioxidants, anti-inflammatories, vitamins, minerals, and more. Again, part of the risk of URI is the inflammation that the physical stress causes on the body, within the tissues and lungs as well as the muscles. Consider joining the Wolf program.
  • Work with a dietitian/nutritionist to personalize your food and supplement needs.

Ready to take your exercise up safely, and protect your health? I invite you to schedule a complimentary New Client call with me, so we can discuss possible best options for you and your fitness!


Cohen, S., Tyrrell, D.A., Smith, A.P., 1991. Psychological stress and susceptibility to the common cold. N. Engl. J. Med. 325, 606-612.

Cohen, S., Doyle, W.J., et all, 2009. Sleep habits and susceptibility to the common cold. Arch. Intern. Med. 169, 62-67.

Jones, A.W., and Dvison, Glen. Exercise, Immunity, and Illness. Muscle Metabolism and Exercise Physiolog. Accessed 20th April, 2020.

McGill, E.A. & Montel, I.N. (Eds). 2017. NASM Essentials of Personal Fitness Training. 5th ed.

Nieman, D.C, et al. 1990. Infectious episodes in runners before and after the Los Angeles Marathon. J. Sports Med. Phys. Fitness 30, 316-328.

Walsh, N.P., et al. 2011. Position statement. Part one: immune function and exercise. Exerc. Immunol. Rev. 17, 6-63.

Article Summary: The Five Things That Happen to Your Body When You Quit Working Out

When you stop working out (even for just a week or two):

  1. Blood pressure increases (within a day, potentially!)
  2. You develop insulin resistance (body converts sugar into fat rather than using it as energy)
  3. Muscle size can shrink within a week (but not necessarily strength)
  4. VO2 max drops (ability to utilize oxygen well. “for every week you remain idle, it takes about three weeks to regain the lost adaptations” Yikes!)
  5. Grumipness takes over (“When you stop exercising, your body forgets how to handle stress. Because you’ve allowed your natural fight-or-flight response to atrophy, you’re less likely to experience something tough—whether an interval workout or a stressful workplace relationship—in a positive way. Instead, you get anxious.”)


The good news? They’re all pretty simple to reverse—or prevent entirely. Just keep moving! 😉


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Fuel Up! Pre-Workout Eats

You lace up your sneakers, don your effects, and rush out the door to get to you workout. You start exuberantly, motivated, and energetic… but halfway through, you start to slow, and feel there’s just no wind in your sails. Or you finish, and you’re famished, entering that “hangry” state.

Did you skip a pre-exercise meal or snack?

The topic of what to eat before exercise can be confusing. A multitude of different organizations, from the Academy of Nutrition and Dietetics, to the American College of Sports Nutrition, or Dietitians of Canada, and more, all have their own recommendations for what you should consume before you go workout, down the specific gram of carbs/proteins/fat to kilograms of your body weight. (We can dive deeper into that another time. The focus here today is just on some baseline ideas.)

Thankfully, they all agree on one important point: do what feels best for you! And it may take some trial and error.

“Training Low,” or intentionally training in a carb-depleted or fasted state, is starting to be studied more. But currently, it is not a typical recommendation. (Speak to your coach or dietitian to see if this is an individualized approach that can safely be done for you, if you are interested) Normally depleted stores are associated with fatigue, reduced work rates, impaired skill and concentration, and increased perception of effort. So generally it is recommended that you consume some proper foods before physical activity to help fuel you towards your goals of weight loss and/or muscle gain.

Having something to eat before going to workout can greatly enhance your efforts. Eating some carbohydrate-rich foods will give you more fuel in your body to help push harder in your workout. A little bit of protein will help with muscle feeding and repair. Hydration is also key, as even mild dehydration can cause drops in your performance, which usually means fewer calories burned or less weights moved. Why not get the most bang for your exercise buck?

It is the amounts, timing, and form of food that are highly dependent upon your own preferences and tolerances. The goal is to provide enough food and fuel before your workout that you can achieve a top-notch effort without feeling hungry, but not too much nor too close to the workout time as to cause cramping, nausea, or other stomach distress.

If you eat 3-4 hours before you exercise, you may do better with a more meal-sized intake. If you eat only 1-2 hours before, a snack will usually do. If you don’t have time to eat well ahead of the activity, a small snack or liquid form may sit best. Just make sure you’re not undoing your weight goals by consuming excess calories! Simply plan ahead to spread your food out around your workout time.

Pre-workout Meal Ideas:

  • Bowl of oatmeal with fruit or honey
  • Brown Rice and Veggie Stir Fry
  • Whole grain bagel with chicken and avocado
  • Salad topped with beans and corn or quinoa

Pre-workout Snack Ideas:

  • Handful of almonds and a cheese stick
  • Fruit and a ½ cup of yogurt
  • Slice or two of wheat toast with nut butter
  • Wheat pita and hummus

Pre-workout Drink Ideas:

  • Low fat milk (some people like chocolate milk, but there is added sugar, so decide if that is right for you)
  • Small fruit, protein powder, and milk/milk substitute smoothie
  • Meal-replacement drink that includes 15-30g Carbohydrate

Bonus Boost: having coffee about an hour before a workout has been shown to boost results! Caffeine is a common aid to help increase time to exhaustion in aerobic endurance exercise bought, decrease ratings of perceived exertion, and improve physical performance even during periods of sleep deprivation.


American College of Sports Medicine, Academy of Nutrition and Dietetics, Dietitians of Canada, a Joint Position Statement. “Nutrition and Athletic Performance.” Medicine & Science in Sports & Exercise. (2016) 543-568. Print.

Campbell, Bill I., Spano, Marie A. NSCA’s Guide to Sport and Exercise Nutrition. Human Kinetics. 2011. Book.

Dunford, Marie; Macedonio, Michele. “A Step-by-step Process for Helping Athletes Achieve Optimal Performance Weight and Body Composition.” Food and Nutrition Conference & Expo. Nashville, TN. 4 Oct 2015. Conference Presentation.

Patgieter, S. “Sports Nutrition: A review of the latest guidelines for exercise and sport nutrition from the American College of Sport and Nutrition, the International Olympic Committee and the International Society for Sports Science” S Afr Journal of Clinical Nutrition 26.1 (2013). 6-16. Print.

“Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance” Journal of the American Dietetic Association. March. 109.3 (2009): 509-527. Print.

Stretch It Out

Here’s a quick task for you (after you check my previous Tabata post and re-read the disclaimer about exercising!) – reach your arms WAY over your head and streeeetch it up! Feel your spine lengthen, your arms press up, and your rib cage expand! Ahhhh!!

Stretching regularly should be a part of a healthy life.  Any activity you do – walking, running, lifting groceries, pulling weeds – your muscles are going to be contracting and flexing. And stretching has its role, too. Of course, if you have any condition, you should check with a doctor or physical therapist about proper care in stretching – it is possible to damage something if you’re not supposed to be stretching it in certain ways.

Yoga is a great way to incorporate strength, breath work, balance, and flexibility!

The Mayo Clinic gives 4 reasons why stretching is important. Now reach both arms to your right and try to twist your spine to reach back even farther on your right as though you’re trying to look behind you, then look back here! You can use the chair to help deepen the stretch.

  1. Stretching increases flexibility: Big deal, right? If you’re not trying to be a yoga guru or contortionist, who cares, right!? Wrong! As you age, you’ll naturally begin to lose the flexibility and muscle performance – this can be needed for even menial tasks like lifting your laundry baskets, bending to tie shoes, or bending your knees to walk up a set of stairs. And if you have better flexibility, it can make these and other tasks easier and less tiring. So rotate that spine the other way, and twist your arms out to the left, and keep yourself loose and limber!
  2. Stretching improves range of motion in your joints: Range of motion helps with better balance and fewer injuries from daily tasks. This is especially important as you age – elderly people have more of a tendency to lose their balance, and due to usually weaker bones, risk more damage from a fall than a younger person. Even if your not at a wizened age, begin implementing preventative care. Stand up, and reach towards your toes! (Or, if you’re refusing to get out of your chair, straighten your legs in front of you, and reach that way.) Perhaps you can practically fold herself in half; or barely touch your knees. Either way is fine! Just listen to your body about what is comfortable yet still gives a slight challenge. Find your own edge, breathe smoothly, and know that your range of motion will improve with practice.
  3. Stretching improves circulation: get that blood flowing! Blood is precious in your body – you need it to get to your heart, to your muscles, and to the joints. And if you’re trying to recover after a good workout and you have those sore muscles, stretching can help speed that recovery. Lean your head forward as though you’re trying to rest your chin on your chest. Sit up straight, keep the spine aligned, and gently stretch those neck muscles.
  4. Stretching can relieve stress: it helps relax tight muscles – whether they are tight from exercise, or tight from stress. Let it go, my dear. Stretch it out!

Aaaand take a big, calming breath. Take another.  And a third, final slow breath.

Start to make stretching a standard part of your week (or even a daily activity.) Here are some pointers from the Mayo Clinic about good stretching and safe stretching:

  • Focus on major muscle groups, such as calves, thighs, hips, lower back, neck, and shoulders. Also focus on muscles and joints that you use routinely.
  • Warm up first, or exercise first. It’s good to have a little blood flow going already – walk a few minutes, swing your arms or legs… or just stretch after exercise.
  • Pace yourself. Reach slowly – don’t thrust too fast or too roughly into a position; hold about 30 seconds, relax, repeat. Do 3-4 times.
  • Don’t bounce! This can actually cause small tears in your muscle (not the good kind used to build muscle), which can leave scar tissue, thereby tightening the muscle more as it tries to heal. This can lead to less flexibility and make you more prone to pain.
  • It shouldn’t hurt. Expect tension, but not pain. If it hurts, you’ve gone too far, so back off a little and hold on that edge.
  • Relax and breathe – don’t hold your breath.
  • Ultimately, it’s up to you how often you stretch. But it’s good to try to stretch after exercising, or at least 3 times a week. You may want to do it more if you have tight joints or muscles.
  • Know when to exercise caution. Don’t damage anything! Learn what feels right, and listen to your body.

I hope that about sums it all up for you! Have a great week!


Tabata, anyone?

 Allow me to first make a disclaimer regarding exercise – I know most of us feel good enough to just jump into things, but I have to say this: See your physician before starting any kind of exercise routine. It is best to work one-on-one with a professional to have your exercise plan tailored just for your needs, abilities, health, and limitations. Use the info at your own risk 😉

Tabata: it’s a modification of the popular High Intensity Interval Training (HIIT), a training type that calls “the best, quickest way to get in shape, lose fat, and annihilate your competition.” Whoa! Well, I’m not trying to annihilate any competition that I know of!

Many personal trainers and coaches will encourage HIIT training to help maximize cardio time. Basically, you do small bursts of exercise, followed by a short rest period (“intervals“.) For example, sprint (“High Intensity”) for 10 seconds, walk 10 seconds, repeat these intervals multiple times. Or, use a bike, and do the same idea – power pedal 15 seconds, cruise for 10. Or use the stair stepper, or rowing machine, etc. (You may want to skip the treadmill, though, as usually changes in speed are lengthier to respond while the belt has to gradually slow.)

There are many different ratios for the bursts-to-rest durations, but all HIIT plans share the same philosophy:

Seriously vigorous activity utilizes extra oxygen as you pant harder and get your heart rate up even higher, and creates an “oxygen debt” – which triggers different mechanisms in your body than when you have ample oxygen to use.

This helps burn off the stored sugars you have in your blood and muscle, and will then utilize fat for energy. Since people are not likely able to sustain this very intense level of activity of prolonged heart rate and full-lung breathing – doing it in spurts is the next best thing.

In theory, you don’t need to do a long, steady workout to burn the same calories – plus, you get an “after burn” even once the exercise is finished, continuing to utilize fat stores for energy for some time after you have stopped.

Post-workout metabolism is boosted for a time as you experience EPOC (Excessive Post-exercise Oxygen Consumption), that time where, even after finishing, you walk around gasping and drooling for the next few hours 😉

In 1994, a group of scientists published a study in the journal Metabolism. They compared a group of people doing typical endurance training (ET) to those doing some HIIT. They found “the HIIT program induced a more pronounced reduction in subcutaneous adiposity (body fat) compared with the ET program” even though less energy was needed. When they corrected for energy costs (ie: if each group were to use the exact same amount of energy for their exercise), they saw that the loss of body fat was nine times greater in the HIIT program than the ET program!

Sounds good, right?

You can see Subcutaneous is the outer layer of fat. But visceral fat is some of the more dangerous fat!

So what specifically is the Tabata Protocol? I am not sure how this is different than any other ratio of HIIT exercise, other than it incorporates a whole plan of building up time and keeping track of heart rates. But I figured it only takes 8 minutes, so I’d give it a try!


The Tabata Plan:

 5 minutes of warm-up
8 intervals of 20 seconds all-out intensity exercise followed by 10 seconds of rest
2 minutes cool-down

So I hopped on an elliptical machine, turned on the ipod to psych me up, and gave it a go! The first 4 sets – not too bad! Panting hard, quads burning, and lungs really working! But I was enjoying the speed. When you’re watching the timer tick for a mere 20 seconds, that’s mentally easier to deal with that seeing it slowly plod along to the 30 minute goal… all 1800 seconds of THAT exercise!

The recommendation is to just start with 2-4 intervals, and gradually work up – but I did the first 4 and just felt like going through all 8!

So I kept pumping – push 20 while I bump the resistance to level 13-15, then cruise for 10 seconds at resistance level 2-4…

By set 6, it was getting tough! But I’d come this far, by golly, I was going to make the last 2 minutes!!

*Pant pant, puff puff, BURN!* Gahhhhh!!!!!

And then… ahhhhh, cruising for the last 2 minutes at level 3… peace. When I finished, my thighs felt like I’d done a pretty decent workout focused on the quadriceps! Wow! And I was shocked how long it took for my heart rate and breathing to return to normal. (Guess I gotta work on that recovery health!) But it felt good!

You want to “feel the burn”? Try some ratio of interval training! Push yourself, dig in, and see what you’ve got! (*Note: but not if you’re new to cardio! This is better for people used to regular cardio work already!)

But don’t forget that any activity is healthy, and all forms of exercise are beneficial – strength training is good for the muscles and bone density. Cardio in steady rates is good for endurance of the heart and lungs – plus helps you sweat out those toxins! 😉 And don’t forget stretching! Flexibility is important for keeping a healthy range of motion, preventing injuries, and keeping circulation moving.

So whatever method you choose – get moving! Even if it’s as simple as a walk at lunch. Or hey – next time you come to read a post here, stand up and do some stretching while you read. Just get that blood moving, and take care of your body. And be excited – you can get a decent workout in 8 to 10 minutes if you really need to! (No, that won’t totally make up for an otherwise chip-eating couch-potato existence… but baby steps to health can be addicting.)