Benefits and Risks of Two-a-Day Training for Cyclists

By Chris Carmichael,
Founder & Head Coach of CTS

For a long time, the concepts of ‘time-crunched athletes’ and ‘two-a-day’ training sessions seemed completely contradictory. Over the past two years, however, I’ve seen an increase in the number of cyclists riding twice a day – not every day – but regularly. That has led to questions from athletes about whether two-a-days are good, how to structure them, and when to do them.

Why cyclists are riding twice a day

One of my first questions as I noticed more cyclists – particularly time-crunched cyclists – riding two-a-days was, why now? In my view, a number of factors have made two-a-days appealing. Smart trainers, Zwift, Peloton, and other brands have made indoor cycling fun, interactive, and community oriented. Descending into your dark basement once to ride a fluid trainer and watch old Tour de France videos took dedication. Twice in the same day seemed masochistic. But a 30-60 minute early morning session on Zwift and a training ride or group ride after work has a different ring to it.

Bike commuting has been another source for two-a-days. More people are riding to and from work and incorporating training into at least one of those trips. Some of them are using e-bikes, but remember you can still ride hard on a pedal-assist e-bike if you want to.

Are two-a-days beneficial?

As with everything else in athletic training, it depends. There are certainly some potential benefits, but they come with downside risks.

Higher volume of workload

When I wrote “The Time-Crunched Cyclist” and when I advocate for high-intensity, low volume training, it’s out of necessity. In the absence of volume, intensity is needed to maintain or increase workload. But spending more time on the bike has always worked, too. So, if two-a-days increase a cyclist’s weekly, monthly, and annual workload, that added stress can be effective for improving fitness.

Energy availability

A lot of research on two-a-days has focused on the effect of doing the second workout in a fatigued and/or energy depleted state. A 2019 study by Ghiarone, et al., compared the effectiveness of two workouts in one day (endurance first, then intervals 2 hours later) three times per week versus the once a day group that followed a “train high, sleep low” model 6 days a week, with an endurance workout in the evening and an interval workout the following morning. Both groups improved performance equally, and the only additional benefits for the twice a day group was increased mitochondrial efficiency and lower perceived exertion during the high intensity interval session.

Although the two groups were matched for workload, the twice a day group had more recovery time between the high intensity workout and the next endurance session. The recovery time may prove important for time-crunched cyclists trying to ride two-a-days, suggesting that a rest day between two-a-days may be better than riding two-a-days too often.

Focus and Recovery

Whether you’re doing intervals or an endurance ride, you perform better when you’re fresh and your performance declines as you get tired. Shortening workouts increases your ability to focus on high quality efforts. There’s also the idea that shorter workouts, even with high intensity, take less out of you and are easier to recover from. After a one-hour high intensity session, you can eat a moderate meal and get on with your day, and then have energy to ride again after work. A 2-3 hour session digs a deeper hole you have to fill in with nutrition, hydration, and rest. This idea was popularized by bodybuilding; you could work a muscle group so hard that it takes a week before you can hit it again, or use shorter workouts in order to recover faster and be able to target muscle groups more frequently.

Other suggested benefits of working out twice a day include increased fat metabolism because you get the post-exercise increase in metabolism twice, meaning it lasts for a longer cumulative time during the day.

Risks and Downsides of Two-a-Days

Overtraining, or at least diminishing returns, is most obvious risk posed by two-a-days. You can easily ramp up total training workload too quickly by using two-a-days to boost weekly training volume. And it’s not just the training stress. Two-a-days increase energy expenditure, and can contribute to relative energy deficiency (RED-S) if you don’t modify your energy intake accordingly. Depending on how frequently you do two-a-days and how much you space them out, you can also significantly hinder recovery between workouts, and hence stall training progress.

Recommendations

Generally speaking, spending more time on the bike is beneficial for performance, whether that’s from more frequent short rides or from making your rides longer. There are some differences between two shorter workouts vs one longer one, as described in this article, but if a time-crunched cyclist has the motivation and ability to ride more, I’m going to do whatever I can to make that additional ride time beneficial. If you are going to ride two-a-days, here are some recommendations:

• Do the harder workout when you have energy. As long as you ate a broad spectrum of foods the day before, you should be rested and have full muscle glycogen stores in the morning, making it a good time for hard intervals. If you perform better late in the day, make your morning workout a moderate endurance ride.
• Start out with one two-a-day per week and see how you handle it before adding a second. Remember that adding workload is a good thing, so long as it’s added slowly.
• Don’t forego all longer rides. You can get to 12 hours of training per week with multiple 60-90 minute rides, or with fewer sessions that include some 2+ hour rides. If you have the time availability in your schedule, adding volume by lengthening individual rides is beneficial, too.
• Eat and sleep more. Some athletes underestimate the energy expenditure and training stress because shorter rides separated by several hours don’t feel as taxing as one longer workout. For two-a-days to improve your performance, or perhaps more importantly, to keep two-a-days from destroying your performance, you have to consume enough calories to support the workload and get enough high quality sleep to facilitate recovery.

For me, the biggest thing keeping me from riding two-a-days more often is all the laundry.