With cold and flu season upon us, I received a reader question about whether or not to train when you’ve come down with a cold. I decided that the 140 characters twitter allowed wouldn’t cut it, so I’ve written a summary of the interaction of intense exercise and the immune system, and a list of the main modifications I make so that I can keep moving the weights despite being under the weather.
Can exercise inhibit immune function?
For years, anecdotal evidence and opinions indicated that athletes were more prone to illness and these often occurred before or after major competitions, suggesting that periods of heavy training seemed to be responsible for the increased rate of infection. When approached systematically, endurance athletes with high training volumes had an increased risk of upper respiratory tract infections (URTI) (1). While controversial, this risk can be roughly associated with training loads, so from a running perspective the more you run in a week, the higher the risk, although this usually occurs at extremely high to excessive training volumes, often centred around major distance races (1,2).
But this blog isn’t about running shoes and lycra shorts (cut well above the knee of course). It’s about picking heavy things up and putting them back down again. And unfortunately for us, strength training is not as well understood; however, there is an argument that elevated muscle damage could divert resources from the body’s immune response towards the damaged muscle, potentially compromising the system’s ability to deal with a viral infection (3). The literature that exists is conflicting, showing either altered (4-9) or unaffected immune function (10-14), that can be difficult to interpret considering that studies use different age groups and training protocols.
Nevertheless, these studies seem to suggest that intensive or exhaustive exercise can create a period of suppressed immune function (3), an open-window, that can increase the likelihood of infection. This open-window theory suggests that under periods of repeated high-intensity training or simply an exhaustive bout of exercise, an early, brief, reduction in the capacity of the immune system provides an opportunity (the open-window) for foreign pathogens (i.e. viruses) to gain traction in the system and ultimately infect the host (you). We have to keep in mind that while studies suggest impaired immune function following an intensive exercise bout, both for strength and endurance training, no definitive link has been made between these early changes and the ultimate risk of getting an URTI.
Now before you quit training or dial it back, keep in mind that these results are primarily from endurance athletes around distance races, and when physical activity is considered as a whole, active individuals often have a decreased risk of URTI than their sedentary peers (1,15). The immunoprotective effects of exercise represent a balance of consistent training with an appropriate balance of volume and intensity that ultimately promote the desired training adaptation.
What if you’re already sick?
But the problem we have here is not whether or not exercise will make you more or less likely to catch a cold, but rather how to adjust your training so that you can at least maintain your progress without prolonging the length of your viral infection. If you buy the ‘open-window’ hypothesis (16), where the immediate suppression of immune function following exercise increases the chances for infection (3), then technically any impairment in immune function from training when already infected with a virus could worsen symptoms and ultimately prolong recovery. In an attempt to prevent and minimize any immune disruption when already sick, I have a pretty common set of modifications I make to my training in order to keep active without making myself any worse off. However it goes without saying that you are the best judge of your capacity to train, and while these are recommendations I use myself, don’t take these as a universal endorsement to train while sick; use your best judgement.
I’ll leave the runners alone for this post, I think that the scientific literature has given them enough attention on this topic as it is, at least when compared to strength training. So for those of us of the iron persuasion, here are a few strategies I use to train when I’m sick:
1. Train less frequently
I would say that most people simply stop training – a viable option, and one that won’t compromise immune function and doesn’t increase the length of the cold. I’m all for strategic layoffs, but when I have an unplanned or prolonged absence from the gym, I find that I don’t feel more rested when I get back to it and usually suffer elevated muscle soreness when I return. To avoid this, I try to get at least the bare minimum done in the gym. While it’s probably not realistic to stick with your normal training schedule (especially if you’re training four or more days per week), a realistic target would be a minimum two days per week of training.
2. Reduce Training Volume
In an attempt to avoid making your cold worse it would be wise to dramatically reduce training volume, at least for the short term, given the relationship between workload and immunity (2). Step 1 above is a good start by reducing the number of training days, but I usually make a few more adjustments beyond just training fewer days per week. To cut volume even further while still maintaining a reasonable amount of training I follow three steps:
- Reduce the number of exercises in the session. I favour compound, multi-joint exercises like squats and deadlifts, and if you are going to eliminate anything, start by cutting out assistance exercises, often single-joint, isolation exercises like bicep curls.
- Reduce the total number of sets during training. If you prefer exercise variety in your sessions and don’t want to cut exercises, reduce the number of sets per exercise and maintain your variety of exercises.
- Reduce the number of repetitions per set. High repetition sets can be difficult when you’re feeling lethargic, so I often cut a rep or two off my planned targets for the day. If I normally shoot for six reps, the set may end at four or five. I focus on keeping movements quick and fluid; you won’t see me grinding out any reps on these days!
3. Increase rest times
Many people, myself included, end up feeling tired, and might end up with a bad case of feeling sorry for yourself. Physiological rationales aside, obviously the psychological effect can have a dramatic effect on your training. I’ve never been a strict enforcer of rest intervals, relying more on whether I feel ready for the lift or not, but I’m sure if I timed my rest out when training through a cold I’d be resting longer than when I’m at 100%.
4. Reduce Training Intensity
I’ve always attempted to maintain intensity (load) in the gym when sick, however it’s not surprising that in practice most weights in training inevitably end up lighter. Since I’ve favoured sharp reductions in training volume by decreasing sets, reps and training frequency through the week, I make a point of trying to maintain a high training intensity (load) or at least not reduce the load as much as the volume. When down with a cold I let movement quality and technique dictate the load and I’m usually able to end up within 10% of my target weight for the day.
5. Reduce Eccentric Muscle Actions
Eccentric muscle actions (active muscle lengthening) are an inevitable and important part of training so it would be difficult to suggest that you avoid them altogether. That being said, eccentrics produce increased muscle damage and pain relative to concentric (shortening) contractions (17-26). This increased damage creates an inflammatory state within the muscle, and places even more stress on an already stressed system, outside of any cold-causing viral infections. The inflammatory response that follows muscle damaging exercise has been proposed to divert precious immune system resources away from providing host resistance (3), that could lead to a increased risk of infection, or potentially prolong an existing cold.
These days more people are experimenting with increased training volume through concentric-only exercise, accumulating additional sets without the elevated muscle soreness and longer recovery times than if those sets incorporated eccentric contractions as well. I haven’t experimented with this one yet, but if I do come down with a cold this year, I’ll try to maintain a higher training volume than usual while using methods with reduced eccentric loading, including sled pushing and pulling using different movement patterns. If you own bumper plates, have technique boxes, or train where they don’t care too much about dropping weights, you can also adapt many conventional exercises to reduce the eccentric phase of the lift (hint: drop the bar).
6. Consume carbohydrates during training
I’m sure many of you out there are already consuming mixtures of carbohydrate and branched-chain amino acids during training for the protein synthetic benefits, but consuming carbohydrate during periods of intensive training may also reduce any exercise-related immunosupression. Given that the bulk of the literature on exercise and immunity focuses on endurance athletes, it’s been shown that a diet 12 g/kg of carbohydrates may promote an enhanced immune response during intentional overtraining (27). But this much carbohydrate is a pretty high dose for the average weight-trainer and given the favour lower-carbohydrate diets have gained lately, any physique-minded reader has probably just given up on my blog.
So before you go stuffing your cold full of carbohydrates, it may be more effective to time your carb consumption around exercise. You’ll find the elevated blood glucose when training with the beverage will reduce the stress of exercise, altering the hormonal response (reduced cortisol), resulting in an improved immune response to exercise (3). Unfortunately, while there are a few studies showing favourable effects on the immune system when carbohydrate consumption is combined with exercise (28-33), there’s no documented evidence that any of these alterations result in a decreased likelihood of contracting a virus or reduce the length or severity of an existing infection. Regardless, this is a simple strategy that is easy to integrate into your training, and it’s definitely cost-effective as the studies used 750 ml of a 6% carbohydrate solution, which you can find in Gatorade (the same “carbohydrate solution” used in the studies). Many strength-trainers have been using mixtures of carbohydrate and protein (or specific branched-chain amino acids) for years anyway; when suffering from a cold or during the common cold and flu season, these drinks could be more beneficial outside of their protein synthetic effects (34).
7. Train at home
This is easier said than done and since I’m spoiled with everything I need to keep training in my basement, going to a public gym is a non-issue. Expanding on that, I’ve previously had as many as four colds per year, however since moving to a home gym this fall, I haven’t had my usual seasonal cold yet (knock on wood). Coincidence? Maybe, but I’ll take any justification I can get to fill my basement full of weights. An additional consideration is that while you need to keep your training going, you want to avoid contaminating equipment and spreading whatever you’ve got to others in the pursuit of muscle. If you are stuck in a public gym, wash your hands regularly, use your sleeve opposed to you hand to cover any coughing and sneezing and be sure to wipe down equipment when you’re finished. You may not be the most popular person in the gym while sick but at least you’ve taken some steps to not contaminate everyone else.
What have you tried?
While none of these recommendations will make your cold go away any faster, by scaling back your training volume while maintaining moderate intensity, you may be able to at least maintain your training without setting back your recovery. Options one to four on the list above represent my usual strategy, although if I do come down with a cold, I plan on integrating more eccentric-free training in an attempt to maintain higher training volumes.
I’d love to hear what adaptations you all make to your training to keep going through what seems to be the inevitable seasonal case of the sniffles.
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