This is a common question I field from the athletes I work with, and especially those who are committing to a Winter training plan in the pain-cave for the first time.  Riding on Zwift can feel more difficult for 3 reasons mainly: the human body becomes less efficient at cooling itself, your motivation dwindles due to not having the wind in your hair and the road moving underneath you, and overcoming the resistance of a trainer is very different compared to overcoming the resistance of the wind/road outdoors.

Problem 1: Inefficient Cooling

This is, in my opinion, the main reason why riding the trainer can feel harder compared to riding outdoors.  The human body has an extremely finite temperature range it can operate efficiently at.  We know that 98.6 degrees F is what’s considered “normal” body temperature, however, push that up just 1.4 degrees F and you feel feverish, have chills, and cold sweats, this is called hyperthermia.  The opposite can also occur in cold and/or wet temperatures when your body temperature dips below 95 degrees F, this is considered hypothermia.  For the sake of this article, we will focus on heat dissipation and avoiding hyperthermia, especially while riding the trainer.

While riding the trainer, the human body is stationary.  However, it is still creating vast amounts of body heat primarily via the metabolic needs of the leg muscles.  As the human body is only ~25% efficient at producing energy (the rest is lost as heat) the core temperature can increase rapidly after the onset of exercise.  If the core temperature increase is not stopped or at least slowed down, hyperthermia occurs which leads to:

• An increased pulse rate.
• Blood is diverted away from the working muscles and towards the skin in an attempt to dissipate heat.  This leads to the muscles not receiving as much oxygen and other crucial metabolic needs which lower the muscle force production.
• The brain literally “cooking” which leads to decreased motivation, concentration, and overall pain tolerance.
• Significantly increased sweat rate in another attempt to dissipate heat which can lead to dehydration and the cascade of accompanying exercise inefficiencies that go along with it.
• As this goes on, exercise eventually becomes impossible and you are forced to stop.

So, from the above, we learned the body cools itself in 2 ways mainly: sweating, and diverting blood flow to the skin.  So, in order to combat hyperthermia, we need to figure out how to make these processes more effective.

External Regulation – Sweating:

Sweating (or perspiration if you are a sophisticated lady 🙂 ) is the process of your body creating fluid on the skin via its sweat glands. The purpose of sweating is for thermoregulation (cooling) by way of convection and evaporation.  Unbelievably, the body can sweat up to 2 liters per hour during intense exercise in hot environments!  So, we need to embrace the sweat (ew!) and get rid of it as quickly as we can to keep our bodies cool.  When riding outdoors, this happens naturally due to wind created by your forward movement, you MUST create this artificially indoors through the use of a fan (and in a perfect world, more than one).

Ideally, the fan’s wind should blow over as much of your body as possible.  Also, make sure you are replacing all of the sweat you are losing and maintaining your body’s hydration level.

Internal Regulation – The Blood:

As previously stated, as the body heats up it diverts blood towards the skin and away from the working muscles which decrease the muscle’s ability to produce force (watts).  Decreasing watt production spells disaster for any race situation or key workout, so how can we keep our body cooler from the inside out?

1. Pre-Cool Yourself:

I am sure you have seen the pros at the large races warming up for a time-trial while wearing what looks like a bullet-proof vest:

This isn’t for safety, this is a vest filled with ice, or placed in the freezer so the gel in the vest becomes ice-cold.  The theory is if you can pre-cool the body before the race, you delay the onset of hyperthermia which improves race performance.

2. Use Ice-Cold Fluids

This is similar to pre-cooling your body, but this can work during the event or workout.  If you can ingest chilly fluids, you will cool your body from the inside out.  Another way to cool yourself efficiently is to spray the cold water on your head as well as on the tops of your hands since there are many capillaries near the skin surface in these areas.  I do not recommend doing this indoors though unless your significant other is a hard-core cyclist like you are!

3. Put the Trainer in Cool Environments

Exercising in the basement (cooler than the main house usually) or in an air-conditioned room makes your body’s thermoregulation attempts more effective since the air temperature will be further from your core temperature.  So, do yourself a favor and put the trainer there!

Problem 2: Motivation

The trainer has also been called “the drainer” by many athletes due to its innate ability to suck the life out of the most motivated athletes.  This is due to some athletes not utilizing the trainer efficiently, some coaches over-utilizing it, and not having the right tools to make it a bearable and even enjoyable experience.

When I prescribe workouts that the athlete will perform on the trainer, I limit them to 90 minutes and ensure they are not just steady-state spinning for the entire time (think intervals).  The trainer is there to get in, do the work, and get out.  If you are spending 2+ hours spinning at Zone 2, you are not only wasting your time but also mentally draining yourself!  Sometimes the long workouts on the trainer are necessary to do, but these workouts should ideally be few and far between.  Do your long endurance/tempo steady-state rides outdoors.

With the advent of Zwift, things have changed for the better and now the trainer is actually becoming enjoyable at times.  I try to have all of the athletes I work with use Zwift for their structured training over the winter since it is so much more engaging than a video, or staring at the basement wall for hours on end.  If you haven’t used the service before, I highly recommend it!

Problem 3: Resistance

This problem is becoming less and less of an issue with the invention of the smart trainer and especially the direct-drive versions.  With the majority of the “dumb” trainers, or the trainers where you leave your rear wheel on, the trainer is exerting resistance via the drum onto the wheel throughout the entire 360-degree wheel revolution.  The spin-down also tends to be very short as compared to riding outside which decreases your rest breaks and makes it harder to get the drum spinning up again.  These factors alone and combined force you to work harder than if you were cruising down a road and only having to overcome the minuscule rolling resistance of the tires (obviously wind-drag is a much larger factor).

Here, Hunter Allen gives an excellent explanation of what I am referring to above:

So, there you have it.  Riding the trainer really can be harder than riding outside, and it isn’t all in your head!  However, if you take some steps and are more proactive/prepared when riding the trainer, the differences between the two don’t feel as bad.