The question of whether running on the road or running on a treadmill leads to faster improvements in running ability has been long debated in the running world. And, with over half a HYROX being running for the majority of us, it’s no surprise that the same question is being asked by HYROX athletes.
So, let’s take a look at what science, elite athletes and their coaches are saying about the benefits and drawbacks of each to help you decide which is right for you.
Energy Expenditure
Running on a treadmill costs slightly less energy than running on the road or on a track. You’ve possibly heard people say that you should set your treadmill to a 1% incline. This is to compensate for the lack of air resistance when running outside.
Now, you might think that as HYROX is inside this is less important for HYROX athletes, and you’d be correct to an extent. However, air resistance is different to wind resistance. Air resistance, also known as drag, is the opposing force that air exerts against a moving object. This force gets stronger the faster something moves.
So, how do we account for this? Well, according to a study by Jones and Doust, the most accurate way to match the energy expenditure of road running and treadmill running will depend on how fast you are running. The study suggested that:
- If you are running under 5:42 min/km you don’t need to use an incline.
- If you are running between 5:43 min/km and 3:20 min/km you could use a 1% incline.
- If you are running over 3:20 min/km you could use a 2-3% incline.
Something else to think about is that many people are using heart rate to train these days. If you’re working in your zone 2 or your threshold heart rate zones, for example, you don’t really need to sync-up your treadmill and outdoor pace. Instead, focus on your goal heart rate and vary the inclines slightly each session. If you’ve had a blood lactate threshold test, you will want to use the paces prescribed to you, but make sure that your incline matches what you used during the test.
Biomechanics
When running fast and in a straight line, the main differences between running on a treadmill and running outside are in specific joint angles. Studies have shown that this is primarily: reduced hip flexion, reduced knee extension and reduced ankle dorsiflexion.
The reason for this is mostly because of how the belt pulls your foot back rather than you having to use muscles such as the hamstrings to propel yourself through space. It also encourages the quickening of your stride, which can see even natural heel strikers become midfoot strikers or forefoot strikers. With a higher turnover and a forefoot/midfoot strike being more efficient for many people, this can result in treadmill running leaving you feeling slightly more efficient than you actually are.
It should be emphasised that this is primarily when doing speed work and so the takeaway should be that unless you are running at speeds over around 3:20 min/km, this shouldn’t be a huge cause for concern. However, when running faster than this, it might be worth considering choosing the track/road over a treadmill to assist you in developing correct and efficient running mechanics.
Leg Strength
We’ve just discussed how running outside requires you to use more muscles than running on the treadmill. A relatively recent study took 24 people and gave them the same running sessions 3 times per week. Half were made to run outside, and half were made to run on a treadmill. As you might expect, both groups got fitter. However, there was a significant increase in the 50m time, mile time, and standing long jump measurements of the group that ran outdoors. Perhaps more interesting was that the outdoor running group held significantly more muscle mass than the treadmill running group.
One thing to consider with these results is that unlike the participants in this study who were simply running three times a week and doing a single bodyweight circuit training session, as a HYROX athlete you will be doing plenty of other things to build your strength: squats, lunges, sled pushes, wall balls, and so on. We wouldn’t expect HYROX athletes following a solid training plan to regress in muscle-mass/strength.
Injury Risk
Injury is the quickest way to stop progressing and even regress in running as it forces you to stop running. It can put you out of a race or even season.
Running on the road, especially in urban areas, will see you navigating various obstacles such as people, dogs, potholes, branches, curbs, hills, lamp posts, as well as dealing with undulating terrain. This unpredictability engages the stabilising muscles of the core, hips, knees, feet and ankles to a much greater extent than the treadmill and even track.
These stabilising muscles are important. Building them through running and accessory exercises in the gym is vital, because it’ll keep them strong and ensure they are less prone to injury.
However, there is an advantage to treadmill running for someone who is injury prone, currently suffering with injuries or coming back from one. Because running on the treadmill will shield these stabilising muscles, you can use it as a tool to get the majority of running benefits whilst reducing the impact and volume on these. Further still, many modern treadmills even have boards and belts that absorb a bit of impact when you run.
Now, as any physio will tell you, shielding muscles that are weak or prone to injury is never a good long-term strategy. Rather, we should work to strengthen muscles that cause us niggles and eventually injuries. So, be sure to introduce/continue prehab/rehab if you decide to use the treadmill as a strategy to reduce muscle/joint impact/usage.
Repeatability
The biggest benefit to treadmill training is that it’s easier to measure and repeat performances without having to account for outside factors. If you want to test your 5000m outside, the weather, wind resistance, surface, obstacles, and uneven terrain could all play a factor – even on the track. On the treadmill, temperature is the only real variable and even that is adjustable with a fan, heater or air conditioning.
This is not just true for testing, but also for managing training. If you are running using metrics of time, distance, blood lactate or heart rate, you can use tried and tested progressions under ideal conditions on a treadmill before testing your numbers under those same conditions to see whether you have improved.
For this reason, the treadmill has become the method of choice for many elite HYROX athletes doing thresholds. For example, James Kelly and Lauren Weeks, have spoken about their successes following this method of training and you will see them utilise treadmills often on their social media.
Beyond HYROX, if you take a look at the Instagram of Olympian and 3000m World Record Holder Jakob Ingebristen, also one of the elite athletes behind the rise in threshold and double threshold training, you can see that many of his threshold runs are done on a treadmill.
All this considered, we must remember that no HYROX is ever going to be done under ideal conditions. As discussed earlier, you will be required to weave around other competitors as you make your way around the track. The shape of the venue and the Roxzone will cause you to slow down and then you must reaccelerate. Some venues will be hot. Some will be cold. Some will have a slicker floor than others.
Mental Strength
This is an interesting topic because whether running or a treadmill is mentally easier or mentally more challenging varies. One person might say that running an interval on a treadmill allows them to just focus on moving whereas someone else may say that they need to be outside seeing and feeling themselves covering the distance.
However, there is a little bit of research on this. One study found that of those they tested, most felt they were running faster on the treadmill than their matched pace on a run outdoors. This contrasts with what we learned earlier about a treadmill costing less energy to run on at the same pace compared to the road. In fact, this study suggests that you are putting in less effort, but it’s feeling harder. I would suggest that this feeling of a treadmill run being faster could be from the higher turnover and form changes that the treadmill encourages.
One thing to keep in mind if you’re one of the people who prefers treadmills: you should not fall into the habit of using the treadmill to run a specific pace because you find running that pace outside too hard. In this case, you should either accept your pace differs on the treadmill/road and stop avoiding the road or look to build your mental strength by challenging yourself to get at least some of your runs done outside (this will pay you back during your next HYROX!).
Which is better for HYROX?
The short version of ‘is running outside better than running on a treadmill when trying to replicate the running in a HYROX?’ is ‘yes’. You probably knew that too! However, running on the curved runner, the motorised treadmill, the track, and / or the road consistently will improve your running.
When we put all the research together, we’re talking about minimal benefits that may well be compensated for by the high amount of strength work we are doing as hybrid athletes so long as we don’t exclusively run on the treadmill.
Even more important, if running on a treadmill leads you to running more often, for longer, and / or reduces your risk of injury then that can only be a good thing!
