What volume and intensity for training during the pandemic?

During this lockdown period, many people are finding alternative activities to road cycling or swimming for triathletes. This includes solid indoor trainer sessions, or even very demanding virtual competitions on Zwift. These training methods are not without risks for physical condition and general health during the pandemic.

By Guillaume Judas – Photos: Paul Foulonneau / Wahoo, pixnio.com, flickr.com

The indoor trainer is in vogue for athletes, and cyclists and triathletes in particular, and for good reason. Outdoor cycling is prohibited until further notice during lockdown, at least in France, unlike other European countries. Experts argue on the one hand the risks involved in cycling sportively over a certain distance and spreading or contracting the virus, as well as the possibilities of accidents that could occupy emergency services and hospitals, which really don’t need that right now. Not to mention the example to set, especially concerning all high-level athletes vis-à-vis the entire population who are asked to stay at home. And on the other hand, we know that regular sports practice promotes physiological and psychological well-being, and maintains good health. And notably by strengthening the immune system.

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In France, it’s not about playing with the rules as established by the government for a few weeks, and specified by Prime Minister Édouard Philippe on March 24. Outings for individual sports practice are a maximum of one hour per day at a maximum distance of one kilometer from home. Sport cycling is excluded, which leaves little outdoors other than running around the neighborhood to let off steam or maintain fitness for cyclists and triathletes.

So there remains the possibility of doing general physical preparation at home, and/or indoor trainer sessions. But this latter practice is not without risks, especially if you intend to fully compensate for the decrease in your usual activity level by riding indoors. It is true that today, certain software or applications like Zwift allow you to pass the time and offer interesting realism while maintaining a competitive spirit. But in the absence of a calendar for resuming outdoor rides to date, sessions that are too long and too intense can primarily produce the opposite of the desired effect.

The dangers of the indoor trainer

Too frequent, too long, and too intense indoor trainer practice has several disadvantages. The first concerns the weariness that can gradually set in and wear you down morally. The period is difficult and we don’t know how long it will last. It’s a kind of interlude for everyone. But it will end one day, and you’ll be able to get back on the road, with new goals to aim for, this summer or at the end of the season. It’s better to maintain motivation by depriving yourself of cycling than to overdo it at the risk of not wanting to do it at all when you resume.

Secondly, pedaling in place and indoors does not ensure good ventilation and causes heavy sweating. You can lose up to a liter per hour, while the body cannot assimilate more than half that amount of liquid in the same time. Hence a fluid and mineral deficit. This causes fatigue, cramps, or other bodily dysfunctions, with muscle or tendon injuries that can bother you for several weeks. The fixed posture on the saddle can also create crotch injuries. In all cases, you must remember to hydrate with an isotonic drink (which improves assimilation speed) and an energy drink with vitamins and minerals during and after the session. A good indoor trainer session can last from 40 minutes to a maximum of one hour. A longer and exceptional session can be considered, but you must weigh its interest against the risks involved.

If your training is based only on intensity, since endurance is not really worked on an indoor trainer compared to the road, you don’t progress.

Exercise series, cardio, watts, it’s good, but in small doses. With training based solely on intensity, since endurance is not really worked on an indoor trainer, you don’t progress. With the factors listed above, you sink into a state of permanent fatigue. Cycling or triathlon are disciplines with a strong aerobic component, and intensity is a bit like the icing on the cake, don’t forget that.

Let’s take this opportunity to talk about competitions on that excellent tool that is Zwift, most of the time very intense but which closely resemble time trials with the need to maintain a high power level for several tens of minutes. Most of them require a very fast start, from the very first seconds. You find yourself facing athletes whose real level you don’t really know, with different devices, calibrated differently, and some of whom are not connected. In short, cheating or arrangements with certain realities are frequent. Nothing serious in itself, it’s just a game. But you shouldn’t get too caught up in it either.

The fact remains that for those who don’t know it, Zwift is the best current tool for long indoor trainer rides. The diversity and choice of routes allow for relatively long rides at moderate intensity, limiting boredom and even meeting friends at the same event. Virtual group rides are even organized. If you manage to control yourself, you can exceptionally participate. But no one can yet confirm that the effect of this type of session is truly comparable to a road ride.

Questions about the immune system

This pandemic period is accompanied by many concerns, as this virus is not yet fully understood, particularly regarding all its modes of transmission. It is therefore highly probable that in the medium term, a good half of the population will be confronted with it, most of the time with invisible or benign signs, fortunately.

Nevertheless, the question arises of our resistance to the virus, or rather that of our immune system when it attacks our body. Sport in general promotes good health and strengthens the immune system, but to what extent? And from what volume or intensity do we become weakened against the virus?

As early as the beginning of the 20th century, scientists had already asked the question by taking blood samples from runners who had just completed the Boston Marathon. They had discovered that the number of white blood cells, a key measure of immune function, was very high, showing the disruption to the body linked to this type of effort. Since then, scientists have debated the link between intense exercise and the risk of contracting transient infections, a question that has never been more relevant than today. Some athletes significantly reduce their activity during lockdown, while for others, on the contrary, it is an opportunity to do more than usual, with also risks of heart problems when the effort is neither habitual nor controlled.

Medical specialists generally describe the relationship between the risk of infection and the dose of effort (a combination of duration and intensity) as follows: regular and moderate exercise would reduce risks compared to a sedentary lifestyle. We even speak of a reduction by half of the typical number of upper respiratory tract infections in the case of almost daily moderate training. However, too great an increase in this dose of effort would reverse the effects of physical maintenance and make one more vulnerable to infections.

What should you understand by an “increase in the dose of effort” that would be detrimental to the immune system? In this area, specialists do not always agree. A study conducted by Professor Neil Walsh in Great Britain in 2015 concluded that two hours of moderate-pace exercise has more negative effects on the immune system than 30 minutes of intense effort. This would mean that a long effort decreases immune functions more than a shorter but more intense effort. However, John Campbell and James Turner, two other British researchers, recently (in 2018) questioned this conclusion by refuting the idea that exercise alone would be responsible for the decrease in immune function. According to them, other factors such as stress associated with certain situations, or even lack of sleep, would have as much influence on the immune system’s response to exercise as the duration and intensity of training.

These exercises must be adapted in duration and intensity so as not to fatigue the body, and not to discourage you while waiting for better days.

What should we take away from this? That there is no question of abstaining from all maintenance during lockdown, and that it is even advisable to maintain regular physical activity, on the one hand to stay in shape to stimulate the immune system, and on the other hand to prepare well for what comes next. But that these exercises must be adapted in duration and intensity so as not to fatigue the body, and not to discourage you while waiting for better days. And as a precautionary measure, it is better to avoid exposing yourself to all risks of contamination in the hours following an effort that you would judge higher than usual.

Of course, the reasonable dose of training depends on your usual level. An occasional cyclist will maintain their fitness with one hour of daily activity at about 60% of their maximum capacity, by running, walking, riding on an indoor trainer, or doing general physical preparation. A diligent triathlete can double their daily training by doing one hour of running in the morning, for example, and one hour of indoor trainer in the afternoon. A road cyclist can exceptionally do a longer ride on Zwift while staying well within the endurance zone, and alternating with shorter sessions with a few intensity peaks. An athlete who is usually trained must take into account their stress level and also think about relieving it in order to strengthen their immune system. But in all cases, adopting a moderate pace in basic endurance interspersed with a few accelerations to maintain strength and power would seem more reasonable for health and for maintaining immune functions during this pandemic period than prolonged intensities, which are better reserved for later.

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