Reebok I Run 4.0 Treadmill Review: Worth Buying?

If you're looking for a new home treadmill, the Reebok I Run 4.0 treadmill is a compact, foldable machine built from the ground up with home running in mind. You'll see it written as the I-Run 4.0 or the iRun 4.0 depending on the retailer; it's the same machine. It aims to strike a balance between gym-style features, sturdy build quality and affordability, while staying small enough to store away when it's not in use.

We have pulled together the consistent themes from verified owner reviews, expert round-ups and Reebok's published specifications, feature by feature, to see how it holds up. So, is it any good?

First impressions and setup

Out of the box, the I Run 4.0 is a little smaller and lighter than most of Reebok's other treadmills, at around 56kg. It still takes two people to lift, so make sure you have an extra pair of hands ready on delivery day.

Setup is quick and easy. It took us roughly 10 minutes from unboxing to starting our first run, with no assembly required: just unpack, unfold and you're good to go. Despite being lighter than some other Reebok treadmills, it never felt cheap or flimsy during testing.

Running belt and cushioning

The running deck is one of the most important features of any treadmill, and the I Run 4.0 does a decent job. It's fairly wide, with similar dimensions to other treadmills in this price range (L125cm x W46cm).

The Elastomer cushioning technology works well underfoot, providing a comfortable, shock-absorbing surface. Many budget treadmills leave your feet fatigued from a lack of cushioning. The I Run 4.0 doesn't have this issue. After 60+ minutes of running, we felt fresh and able to keep going.

Display

The 4-window LED display is bright and modern, built into the front of the machine just below the tablet holder. It feeds back on speed, distance, time, calories, pulse, body fat and your total step count.

The body fat guide is a nice touch. It uses the integrated hand sensors along with your gender, age, height and weight to estimate your BMI. BMI isn't a perfect measure of fitness, but it's handy for tracking rough progress on your fitness journey.

The most notable drawback is the lack of Bluetooth. At this price, we'd expect every treadmill to connect to your phone so you can track runs in a fitness app. It's a shame the I Run 4.0 misses this, though if you're not bothered about app tracking you won't even notice. Otherwise, the display covers all the metrics you'd want while running.

Speed and incline

The I Run 4.0 has a maximum speed of 16 km/h (approx. 10 mph), powered by a 1.25 HP motor. It feels smooth and runs almost silently, so you won't wake the family or neighbours during early-morning workouts.

There's no adjustable incline, which is a shame, but it does have a fixed 4-degree incline. It's barely noticeable, though a slight incline while walking and running has been shown to be better for joint health.

Speed is adjusted using the buttons below the display. We'd have liked integrated handlebar controls at this price, but Reebok seems to have opted for a sleeker, simpler design here. It's not a dealbreaker, just worth noting.

Programmes

This is where the I Run 4.0 really comes into its own. The 12 programmes are easy to access and cover a range of walking and running sessions to suit all abilities, from the gentlest stroll to the most gruelling run.

On top of the 12 presets, you get a choice of 3 target workouts focused on time, distance or calories burned. We loved this feature, and often found ourselves pushing to hit a calorie target before ending a session.

Build quality

As with every treadmill we review, we put the build quality to the test. Plenty of training programmes are all well and good, but you want a machine that's going to last.

Straight out of the box, the frame felt solid and strong for the price. We were impressed by how light the 4.0 is compared with other treadmills in this bracket. It's still heavy, just not quite as heavy as some rivals, and it folds and unfolds smoothly without any hassle. In use, the machine stays sturdy without rocking, moving or rattling, and runs with very little noise thanks to the cushioned deck.

Warranty

Reebok always provides great warranties, and this treadmill is no different. It comes with a 10-year motor warranty as standard, so you're covered if anything goes wrong with the motor through no fault of your own. You also get a 2-year parts and labour warranty.

Who the Reebok I Run 4.0 treadmill suits

Runners doing two or three sessions a week in a house without a spare room. That's the honest answer. The 1.25 HP motor and 16 km/h ceiling cover everything from a walk to a decent tempo run, and the 120kg user limit is more generous than most machines at this money, but a 1.25 HP motor asked to shift a heavy runner for an hour a day, five days a week, will age faster than one doing three easy 5ks.

It's also a reasonable buy for a two-person household with mixed goals, since the 12 presets and three target workouts give a walker and a runner different things to do without either fiddling with settings. Where it falls down is anyone who wants hill training. The incline is fixed at 4 degrees and there's no way to change it, so if gradient work is the point, our best incline treadmill UK guide is the better starting place.

How it compares

For a similar price, you can pick up the Reebok Jet 100 Treadmill, which we've also tested. It has more features than the I Run 4.0 and a larger running surface. The one important difference is the maximum user weight (120kg on the I Run 4.0 versus 110kg on the Jet 100).

Inside Reebok's own range, the i-Run 5.0 is the step up, and the incline is the whole difference: 12 powered levels and app support against the 4.0's fixed 4 degrees and no connectivity at all. If hills are the reason you're shopping, that's the model to look at rather than this one.

Is the Reebok i-Run 4.0 treadmill worth buying now?

It hinges almost entirely on how often you'll use it. A 1.25 HP motor is sized for two or three sessions a week, and the 10-year motor warranty tells you Reebok expects it to last at that rate rather than at an hour a day, five days a week. Ask a small motor to do a big machine's job and it ages accordingly.

The spec that has aged best is the 120kg user limit, since plenty of newer folding treadmills at this money still stop at 100kg or 110kg. What's aged worst is the missing Bluetooth. Cheaper machines now sync to Kinomap and Zwift, so if app-led sessions are the thing that keeps you on a treadmill, this one will start to grate within a month.