When Runner's World readers were asked to list their essential kit last year, heart-rate monitors came out on top. Unfortunately for the female runner, using a heart-rate monitor is usually an uncomfortable experience, requiring 10 minutes before

Heart-rate monitors vary hugely in price and functionality. For less than £20 you can pick up an HRM that simply measures your pulse, while parting with £150+ will give you a monitor that will set training zones for you, tell you how many calories

.Contact: 01926 816166; www.polar-uk.comCardiosport GO £39.99 Back-to-basics model. Display simply shows HR. One button allows you to scroll through work-out time, minimum, maximum and average HR for one session.Contact: 0800-146 224; www.cardiosport.com

when you start seeing the results of better fitness and faster times.How does an HRM work? If you haven’t used one before having a basic understanding of how a heart rate monitor works will help you to get the best out of yours. There are two parts

for women. It does the basics well enough, though, and it's pretty good value for £40.Contact www.oregonscientific.co.ukSigma Onyx Pro, £95 Features 3 HR zones, 50-lap memory, pre-set programsRW Says The Onyx Pro is a sturdy and minimalist-looking HRM

to check our progress at least once in a while.The most basic thing to look for is a memory function to record mile times in races or lap times in speed sessions. Many running watches also have countdown timers. These aren’t essential, but a good one can

, countdown timer, Hi/Lo Target Zone with audible and visual alarm.Reader Review The GT5 is heart-rate monitor with all the typical functions; basic stopwatch, training zones, interval training and the ability to record workouts and then upload them to a PC

to read, although the total time, rather than lap time, is most prominent, and the ‘Adidas’ button that starts and stops the chronograph is small and not at an ideal angle to hit. Recalling the data in the memory is simple, and there are three basic

of it's weaknesses, the RS800SD is a serious bit of kit that will definitely help your training. You can keep it simple and just use a basic mode to record your run data. Or if you are prepared to put in the effort, create customised heart rate training