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By Jane McGuire published 21 February 22
It’s a cardio face-off.
When it comes to cardio machines, treadmills and exercise bikes are by far the most popular. Think back to the pandemic, when companies faced shortages as we rushed to add the best treadmills and the best exercise bikes to our spare bedrooms — both machines are an excellent way to increase your cardiovascular fitness indoors.
That said, if you only have the space or the budget for one machine, or you’re wondering which to use on your next visit to the gym, you might be wondering which will give you a better workout. The answer really depends on your goals, your fitness level, and your body, but we’ve broken down the pros and cons of each machine to help you work out which suits you best. We’ve also looked at the treadmill vs the elliptical machine here.
As appealing as running outside might seem, there are times when the weather, climate and/or your schedule may make going outside for a jog a no-go. Enter the treadmill. As versatile as they are convenient, these cardio machines enable you to walk, jog or run indoors on a soft surface that’s kinder to your feet and joints than concrete or asphalt. Most treadmills enable you to adjust the speed and incline, which means that you can tweak your workout to suit your own individual needs.
Treadmills will generally have arms on either side of the moving belt, which you can grab onto for support should you need. Most treadmills are motorized, which means the belt will move underneath you. In recent years, non-motorized treadmills and under-desk treadmills have also become popular, which require you to move the belt yourself to increase the speed.
Exercise bikes, on the other hand, afford the opportunity to enjoy a lower-impact aerobic workout. This enables you to strengthen and tone the muscles in your legs and glutes without having to worry about injuring or straining yourself. Most bikes enable you to adjust resistance levels, with most affording a choice of low, medium and high resistance settings.
There are a number of different styles of exercise bike on the market. Some will be like spin bikes, which resemble a road bike you might cycle outdoors. Others are designed for a more comfortable ride, and some even allow you to sit and cycle your legs while supporting your spine — these recumbent bikes are brilliant for older cyclists.
If you’re a runner, the treadmill might seem like the obvious choice and in many ways it is, as a treadmill will mimic the action of running or walking outside. If you’re a runner, using a treadmill is a great way to strengthen the muscles you’ll need on race day, while being able to control the conditions.
Another huge plus of the treadmill is that it gives you huge versatility, as you can control the pace and incline at the push of a button. Whether you want to torch calories by power walking up hills, or work on your speed with some sprint intervals, you have complete control. Because of how much control you have, the treadmill is a brilliant cardio machine for beginners.
While you can get a similar calorie burn on both the treadmill and the exercise bike, traditionally, you’ll burn more calories when running on a treadmill than you will on the bike. This is because you’re standing up and bearing your own body weight when running or walking on the treadmill. One study (opens in new tab) found that on average, running on a treadmill burns 8.18–10.78 calories per minute, while stationary cycling burns 7.98–10.48 calories per minute.
As a treadmill is a higher-impact exercise, it has a higher injury risk than cycling on a stationary bike. That said, some of the most common running injuries, including shin splints, stress fractures, and knee pain, can all be caused by doing too much too soon, so if you are new to the treadmill, take things slowly, and be sure to warm-up before jumping on.
While treadmills are a brilliant training tool for runners, they aren’t quite as effective as running outside, as the belt is moving underneath you. One of the downsides of running on the treadmill is that the belt assists leg turnover, meaning you don't have to work quite as hard. When running outside, you’re also forced to not just move in a linear motion, as you’ll often find you have to dodge people, cars, and objects on the sidewalk as you move. We look at the pros and cons of running on the treadmill vs outside here.
Finally, for some people, the exercise bike will be a better option for their bodies. If you’ve experienced knee pain or a knee injury in the past, riding a bike might be better on your joints than running or walking on the treadmill.
The exercise bike is one of the best low-impact cardio options out there and if you struggle with joint pain, indoor cycling might be a better option than running on the treadmill.
Like treadmills, exercise bikes allow you to alter the resistance and intensity on the bike, allowing you to really push yourself, or take things easier when you’d like to. As mentioned above, there are a number of different styles of exercise bike to choose from, but if you really want a workout, a spin-bike style is the best option for you.
You are also able to work up a sweat and torch calories on an exercise bike should you wish. In fact, some studies have shown that your calorie burn cycling can be as great as running if you up your speed and resistance.
Like treadmills, exercise bikes are well-suited for beginners, as you can hop on and go, without having to learn new skills. Finally, exercise bikes can be cheaper and far more compact than treadmills, if you are looking to add one cardio machine to your home gym.
While there are huge pros to lower-impact exercise, there are also some downsides. As cycling on a stationary bike isn’t weight-bearing, you won’t get the same bone mineral density (BMD) benefits that you do when running and weight lifting.
It’s also harder to build muscle on an exercise bike than it is when running on a treadmill, but this shouldn’t be too much of an issue if you’re supplementing your cycling with strength training.
When deciding between the two cardio machines, it’s important to have a think about which type of cardio you enjoy the most. You don’t want to invest in a treadmill for it to become an oversized clothes horse, but equally, you don’t want to buy a bike to then spend your time running outdoors. Often getting started is half the battle, and you’re more likely to get going if you enjoy using the machine.
Next, think about your goals. If, for example, you’re training for a 5K or a half marathon, a treadmill might be the better option, as it’ll help you strengthen your stride, and keep you from missing miles in bad weather.
How your body works best is also an important part of this decision. If you frequently have to take time off working out with knee pain, an exercise bike might be a better option.
Finally, if you’re investing in either machine, it’s a good idea to look at your budget and the space in your home. Treadmills require a much larger footprint and often need a good amount of headspace above to allow the machine to incline, making them tricky to fit in some garden sheds or garages. Exercise bikes, on the other hand, are often smaller and cheaper.
Whichever machine you choose, you’re bound to get plenty of positive benefits, but like all new workout regimes, it’s a good idea to check with your doctor or personal trainer before starting out.
Jane McGuire is Tom's Guide's Fitness editor, which means she looks after everything fitness related - from running gear to yoga mats. An avid runner, Jane has tested and reviewed fitness products for the past four years, so knows what to look for when finding a good running watch or a pair of shorts with pockets big enough for your smartphone. When she's not pounding the pavements, you'll find Jane striding round the Surrey Hills, taking far too many photos of her puppy.
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