What
Cycling cadence is the number of revolutions of the crank per minute, or simply the pedal revolutions per minute.

Why
When trying to improve efficiency in cycling, there are few things a cyclist can change - effort (heart rate), gearing (shift lower or higher) and cycle cadence (revolutions per minute). A cycling cadence monitor, alongside a heart rate monitor, is used to optimise the cycling exercise to your goals such as fat burning; muscle building or strengthening heart and lungs.

What
Many trackers today contain a device called an accelerometer. It measures movement and acceleration. This allows devices to record both the start and end of an activity, as well as its intensity.

Why
Using both measures of how much and how intense activity is, trackers are better able to calculate calorie counts. Some devices will set activity goals by intensity - a walking goal and a more rigorous exercise goal.

What
A Global Positioning System (GPS) receiver is a device that allows users to pinpoint exactly where they are and how fast they are moving.

Why
Activity trackers with GPS provide valuable information for users who exercise over distances outside (Runners, Cyclists, Swimmers, Footballers, etc.) including distance travelled, pace, and path travelled. All of these metrics are valuable for monitoring performance while training.

What
A heart rate monitor tracks a user's heartbeats per minute. This can be used to calculate the percentage of effort you are using (out of your maximum suggested heart rate). They do not track a user's blood pressure.

Why
Heart rate monitors can be used during exercise to help users manage the type of exercise they perform. Heart rate monitoring makes sense for anyone who wants to optimise their exercise to achieve specific goals. The table below shows what benefits different heart rates zones offer.

What
Run cadence is a measure of how many times a runner's foot hits the ground in a minute of running, or simply the steps per minute.

Why
Expert runners monitor their running cadence to fine tune their stride because there is a school of thought that suggests increasing your running cadence both increases your running efficiency and decreases your risk of running-related injuries. While everyday runners' cadence generally falls between 160 and 170 steps per minute, elite runners by and large get to at least 180 steps per minute.

What
Some trackers are able to track the quantity (hours and minutes) and quality (absence of movement and sound) of sleep to varying degrees using various methods.

Why
Managing and improving your sleep can help: Lessen our likelihood of obesity, since sleep deprivation can increase appetite; reduce our risk of diabetes and heart problems; improve our concentration, reaction time and memory; boost our moods and creativity; Enhance our immune systems to help ward off colds and infections.

What
A step counter, also known as a pedometer, tracks the number of steps someone takes in a day.

Why
Counting steps is a great way to monitor your daily activity, and a useful way of managing it. The average person in the UK walks 4,000 steps a day. However, research has shown when people walk 10,000 steps a day it helps to maintain their health and walking 12,500+ steps a day can help with weight loss.

What
Some activity trackers use the accelerometer to measure the number of strokes a user performs in a pool. This can be used to determine a user's distance travelled without GPS.

Why
Swimmers can improve their swimming technique by working to reduce their SWOLF score. SWOLF is an abbreviation for "Swim Golf" and is a score obtained by adding together the number of swim strokes per pool length, and the time it took to swim that length. For instance, 30 seconds and 10 strokes to swim the length of a pool will equal a swolf score of 40. A lower score is better, just as in golf.