While you're going or once you're done, you can use your smartphone to check your heart rate, distance travelled, speed and intensity level of your workout.
However, while many accessories rely primarily on their own app, the Zephyr Heart Rate Monitor is compatible with numerous third party fitness apps, such as Endomondo, MapMyRun and Runtastic.
So if you already use a fitness app you can just slot this in to improve its tracking capabilities.
4. JayBird Sportsband 2 (£69.99)
Tracking calories, distance and heart rate is all well and good, but you shouldn't underestimate the value of a good tune during a workout. It can prevent it from becoming monotonous and even get you energised if you listen to something suitably upbeat.
The problem is that most head and earphones aren't designed with sports in mind, but that's exactly what the JayBird Sportsband 2 was created for.
The JayBird Sportsband 2 passes the first hurdle by being grippy enough to stay in place when running or playing sports. It also has a lightweight construction so it won't weigh you down or distract you and as it links to your phone via Bluetooth there aren't any wires to get tangled up in.
But it goes further than that with on-ear music controls, which let you change the volume or skip track all without fumbling with your phone or trying to find controls on a cord.
It can be used to take calls wirelessly too and to top it all off it looks damn fine.
5. Withings Smart Body Analyser (£129.95)
The Withings Smart Body Analyser might just look like scales, but it's a whole lot more than that.
Yes if you step on it you can get an ultra precise measurement of how much you weigh, but it can also tell you how much body fat you have, tell you your heart rate and even check the quality of the air, so that you'll be better able to optimise your environment.
Couple it with the Withings Health Mate app for Android and iOS and it can also upload your data and let you set weight goals, which it will then break down into achievable weekly targets and let you see your progress.
6. Jawbone UP (£99.99)
The Jawbone UP is another fitness band, though perhaps one that's less well known on these shores than Fitbit or Nike's offerings.
It certainly matches them for features though, as it can track steps, distance, calories burned and the amount of time that you spend idle versus the amount of time that you spend being active.
It can also tell you how long you sleep for, how long it takes you to fall asleep, how many times you woke up during the night and how long you spend in light versus deep sleep.
It has a ten day battery life and while we wouldn't exactly call it stylish it's not the worst thing you could wear on your wrist either.
Like the Fitbit Flex it doesn't have a display, so you'll have to use the 'UP by Jawbone' app for iOS and Android to see how you're doing. As well as showing you all the tracked data, the app also lets you log food and drink and set goals.
And to allow you freedom with your exercise: the Jawbone UP is compatible with some other fitness apps, such as RunKeeper and MapMyFitness.
7. Tune Belt Sport Armband (£16.99)
There are loads of smartphone armbands out there and if you plan to use your phone for fitness tracking or listening to music while you work out, investing in one is all but essential.
The Tune Belt Sport Armband isn't much to look at but it does the important stuff, namely keeps your smartphone securely fastened to your arm while protecting it from bumps, scratches and the elements.