JLL S400 Treadmill Review

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The JLL S400 is the latest in the JLL S range of treadmills and follows hot in the footsteps of the much acclaimed S300. Boasting a larger running area and benefiting from a minor facelift, the S400 looks set to tick a lot of boxes.

We decided to take it on a few test runs to see if it lived up to the hype or whether it was just an overpriced run of the mill treadmill.

Find out what we thought in our JLL S400 review below.

JLL S400 Specs

JLL S400 Treadmill

There is no denying the JLL S400 looks like a beautiful piece of kit. In fact, the robustly designed frame houses bold but sleek lines and a feature list that would be welcome on a treadmill at any commercial gym.

The upgraded larger frame makes for an imposing look and gives many S300 users what they have been screaming out for – a larger running deck.

The running deck on the S300 was not exactly small, but runners with long strides and those over 6ft will be glad of the extra stride space that the S400 accommodates.

The JLL S400 treadmill provides a running track that measures 135cm (l) x 45cm (w) which is 12cm longer and 4cm wider than its predecessor – not too shabby at all!

When in use the S400 measures up at 170cm (l) x 70cm (w) x 134cm (h) and it is fully foldable which reduces the dimensions for storage down to 110cm (l) x 70cm (w) x 134cm (h).

This makes the S400 ideal for home use and with a total weight of 69kg you will be glad to know it also comes with handy transport wheels so you can manoeuvre it around the room to your favourite position for your run.

The motor is the same as its sibling so you will find a powerful 2.5HP (1800W) continuous DC motor with a peak power output of 4.5HP (3600W). The price difference between this and the older model is not that great and there was never an issue with the motor so we are confident that this newer model will have no issues using the same tech.

Expect top speeds of 16KM/h that are easy to select with a range of quick speed keys that can get you up to 5KM/h and 8KM/h in no time.

The running track is designed to absorb shock and provide a run that is not going to upset your joints. A 16 point internal cushioning system is designed to absorb the impact from each stride and should allow you to run for longer without additional pain.

There are 20 levels of incline to choose from and these are mechanically driven so you can simply choose your incline using the buttons on the centre console and the machine will do the rest (except for the running of course – you still need to do that). The range of incline is from 19cm above floor level to 26cm above floor and this is the same as the S300.

The JLL S400 has you well covered when it comes to the onboard computer and entertainment provision. There are 15 pre-set running programmes to choose from, 3 of which can be custom set. The range of pre-sets is impressive and you can also use the in-built pulse rate sensors to work at your target heart rate for optimum performance.

There is a USB port for connecting your smartphone or a flash drive to play music or you can connect using a standard AUX port as well as via bluetooth. The USB port can also be used for charging your device and the music plays through the internal speakers which are above average compared to other treadmills at similar price points.

The centre console is a clear focal point when running and is well positioned and angled. It includes a range of soft, easy to navigate buttons as well as all the data you would expect to see on the backlit 5.5″ LCD screen.

JLL have backed the S400 with an excellent warranty package and provide a lifetime warranty on the frame, a 5 year warranty on the motor and a 2 year warranty on all other parts and labour. This is a market leading warranty for treadmills at this price point.

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JLL S400 30 Day Test

JLL S400 screen

The JLL S400 could well be the best treadmill in its class. The improved running track size takes the single biggest fault of its predecessor and tackles it head on to provide an ideal running track for pretty much all size of runners.

We were excited to start testing the S400 and we had to try and not get carried away with our assessments before we have even set foot on the treadmill – after all, we had a good 3-4 weeks of testing ahead of us.

The first thing you will have to do upon taking delivery of the S400 is set it up. This is always a moment that we dread and when you see the two box delivery arrive your heart starts to sink.

Luckily, JLL really have made it as easy as possible to assemble this treadmill and 45 minutes later we were literally up and running. The instructions are very clear, well written and easy to follow – although you will need two people for the assembly process just because of the size and weight of some of the parts.

In total, we used the S400 23 times. The majority of our tests were for short 10 minute periods but we also used it for several 30 minutes runs and also one 60 minute run. Our main tester did no other running during the testing period and usually runs using a combination of commercial gym treadmills and road running.

The first thing to report on is the comfort level of the run as this is usually a deal breaker for us when it comes to treadmills over the £500 mark. The S400 is about as good as it gets in terms of suspension and shock absorption and the 16-point cushioned deck really does help prevent any unnecessary stress on the joints and muscles.

At the same time, the deck feels very stable and is not overly bouncy as you find with some models. This provides a good overall feel for your run with a deck that is responsive to your stride but not overly so.

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s400 runner

The deck size makes a huge difference with the S400 compared to the S300 and although the width is only 4cm wider this is where our tester found the biggest difference was made.

You feel so much more secure having that extra leeway each side and of course the extra deck length also aids with this and allows you to feel like you can really push yourself.

All aspects of the S400 feel intuitive, from the centre console to the quick speed and incline buttons found on the arms of the treadmill. The pulse rate sensors are also located on the robust arms and these provide fairly accurate readings as well as a good deal of support being offered from the arms themselves.

When it comes to the running, the pre-set programmes are more than enough to provide you with a range of stern workouts with the heart rate programmes being our favourite.

Sadly, there is no third party connectivity with Polar heart rate monitors or any extended functionality through the use of an app – but to be honest this isn’t really needed as the treadmill does a fantastic job as a standalone unit.

The motorised incline works seamlessly and the transition from the lowest to the highest incline setting is smooth. The highest setting really does provide plenty of challenge and for anyone looking to burn calories using a treadmill the incline really will make a difference and allow you to be more efficient with your workouts by burning calories quicker.

The connectivity and quality of speakers is not usually something we get that excited about when it comes to home gym equipment (for music purposes at least) but the S400 does a really good job in terms of connectivity and sound quality.

If you have a top quality sound system at home you are probably going to continue to use it but if not or you just want the convenience of being able to plug in to your treadmill and play your favourite tracks then this is a welcome bonus as far as we are concerned.

We really enjoyed using the S400, so much so that we didn’t want to give it back at the end of the testing period. It may not be the cheapest treadmill on the market but it is probably the best value for money – and when you consider the impressive warranty it should last too.

JLL S400 Verdict
  • Value For Money
  • Ease of Use
  • Connectivity
  • Comfort Level
  • Features


The JLL S400 is a good step up from its predecessor and the larger running track makes the world of difference. The level of comfort and ease of use that the S400 affords when using the treadmill is excellent and the folding mechanism makes it ideal for compact storage.

There is plenty to keep all levels of runner interested and challenged and this is an investment that should serve you for a long time thanks to the excellent warranty provided by JLL.



Excellent value for money

Mechanical incline works well

Powerful motor

Decent quality speakers


No connectivity for third-party heart rate monitor

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