Altering Your Training to Boost Your Immune Function

Getting from point A to point B in life - goal attainment - involves overcoming the inevitable obstacles that impede our forward progress. COVID-19 is obviously an obstacle and an impediment. Races are postponed or cancelled altogether. Group rides are out with respect to social distancing rules. The normal goals and routines of our cycling life have been upended. So, it is time to redirect our focus. We can still maintain structure and training with some of our races kicked down the road. We can now just take more time to build fitness more methodically, take more time to identify and shore up our weaknesses and just generally build a broader base. 

We also need to plan our activities and training and lifestyles around the need to keep ourselves healthy. We will all at some point be exposed to the COVID virus. One variable that will help us resist becoming infected, and have better outcomes if infected, is a healthy immune system. 

In my last article I discussed at length the concept of the stress/adaptation model, the fundamental precept being that we adapt to external stress and, provided the stress doesn’t exceed our ability to adapt to it, develop a resistance to it and become stronger. Does this same principle apply to our immune function? Can we train our immune system through repeated and controlled doses of stress to improve its function? Can overtraining, either acutely or chronically, depress our immune system? 

Let’s look at the research. It is generally accepted that regular aerobic exercise improves our immune system, and public health guidelines recommend 30 minute of exercise a day. Even recent more recent research has pinpointed the mechanism by which aerobic exercise can maintain healthy immune function in older adults (Dugal, et. al. 2018), and regular aerobic exercise even increases the effectiveness of vaccines. And the good news is that it doesn’t have to be a lot - typically 30 minutes or so of moderate and sustained aerobic activity. 

Most of us ride more than 30 minutes. Some of us ride a lot more than this. Some of us even willingly do pretty strenuous things on the bike like centuries, gran fondos, long and difficult mountain climbs and any number of activities that push us to exhaustion. It begs the question, is there such a thing as too much of a good thing? Although there is no clear scientific consensus that it does, and there are opposing camps here, there is ample research that highly competitive endurance athletes tend to suffer from high incidents of upper respiratory tract infections (Galesza-Franta, et. al, 2016), and URTI infection rank 2nd to knee injury as an obstacle to training consistency, and even a particular hard bout of training lasting longer than 90 minutes can create what we can refer to an “open window” of impaired immunity that can last anywhere from 3-72 hours after exercise where viruses are more likely to cause infection (Neiman, 2003)

Considering that COVID 19 is a highly contagious virus that targets the upper respiratory tract, the activities that we do that influence our rate of infection are of obvious relevance. So, how to we form some general guidelines for riding and training going forward? What are some specific workout strategies we can use to follow these guidelines? 

Well, for one, the postponement of the events and rides we want to do till the Fall give us some time to plan a longer, more methodical training plan. Most of us have probably also had our training interrupted by the shelter-in-place orders and we have probably lost fitness. Getting our training back on track is the first objective. Doing so without putting us in a hole is the first thing. Many of us may have been in a build phase. It is probably best to go back to a late base phase or early build phase. If you were doing intervals, double check your training zones and dial it back a little, both in the prescribed intensity and the number of intervals. 

Let’s take an example. I have a client who was ramping up his training leading up to the local MTB racing series. I prescribed him on a once-a-week high intensity workout of 30 seconds maximum effort / 15 seconds recovery. This is a very challenging workout, and really puts a strain on your maximal aerobic capacity, which is ultimately the point because we want to improve it, as well as the ability to do repeated hard efforts at VO2 or above - the kind of thing a mountain bike racer will encounter. 

It’s been shown to be a very effective workout, both in raising threshold power, but also raising VO2. It’s also very stressful. I consider it a peaking type of workout - something to throw at my client in a final build phase before key races. It puts an athlete above that 2nd Ventilatory Threshold, which means they’re gasping for breath. This is the kind of thing that will make the upper respiratory tract vulnerable. 

Instead of this particular workout, I’m adjusting the duration and the rest interval. Rather than a 30 second maximum effort and short rest, which put him squarely at his VO2 max, I give him fewer reps, lower the duration and increase the rest interval. In this case 15 seconds max effort followed by 2 minutes or so of recovery. The emphasis is more on developing peak neuromuscular strength and some fatigue resistance to hard efforts - maybe improve the ability to recharge ATP/PCr if we tweak the recovery interval a little. Once the time comes to lengthen the interval and shorten the rest and add reps, his time doing these  workouts will have helped him, so we can really think about this as stretching out the base and build phases to prepare the athlete better for the hard work ahead. 

I will also prescribe more steady state intervals in the 8 minute range. These are good for building threshold power, and typically the intensity is around 100-108% of FTP. Again, this is a tough workout. For now, I’m going to dial back the intensity to 90-100% of FTP, depending on what the athlete has been doing prior. It’s not an easy workout, and still gives a training stimulus, and has the additional benefit of not being so grueling that an athlete can continue to do this consistently without mental and physical fatigue. This is a great workout to program into Zwift or TrainerRoad for the indoor riding many of us seem to be confined to. 

Longer Zone 2 workouts are still recommended, depending on your comfort level for outdoor riding and social distancing. I would recommend that you not increase the duration of these rides too much or too quickly. If anything, keep them the same duration or even reduce the duration. For example, if you ride for 3-4 hours, don’t bump the duration to 5 hours, and make sure to keep the intensity on the lower end - about 65-70% of your FTP or even less. 

And make sure you have adequate carb intake - maybe even consume more than usual on rides. One strategy in the early season is to do your longer rides in a glycogen depleted state to improve the ability to utilize fat as a fuel source and to lose body fat. I’d skip this. It’s pretty stressful on the immune system. Instead, alter your overall diet with foods that have more anti-oxidant properties, which can particularly provide a benefit to the immune system of an athlete (Elkington, 2015).