The Timex Bodylink mainly serves as a GPS distance and speed calculator and heart rate monitor - it is also a watch. The GPS component runs on a AA battery, while the watch shares the same battery as standard Timex and other digital watches. The GPS component attaches separately to your wrist or pocket.

The heart rate monitor comprises a strap with sensors that you wet and wrap like a belt around your chest or sternum. Without the heart rate monitor and the GPS component, you have a nice-looking Timex watch you can wear around with "Ironman Triathlon" etched in small letters.

The watch function, however, represents only one of the many features the Timex Bodylink offers. Indeed, there are too many options to list and detail for this review. Like an engineer's calculator, the Timex Bodylink offers an abundance of features that your average user will likely not exploit, but they are there if desired.

The main feature, for the scope of this review, falls under the Chronograph mode, which allows you to monitor your distance, speed and heart rate. To use this and most of the other options, the GPS sensors and heart monitor strap must be attached to your body. Pressing Start/Split in Chronograph mode activates the readings. When you press it again, the distance, speed, heart rate and other tracking functions are reactivated and are recorded as a second lap.

Taking separate readings for 100 laps is possible. One potential usage scenario is that during interval training you run a sprint for lap 1, jog an eight-minute mile for lap 2, sprint again for lap 3, and so forth.

For more detailed interval training tracking, the Interval Timing mode allows you to set times for as many as five different sessions. For example, you can create a workout during which you run, ride a bicycle and then cool down by walking for a set period of time. You can also program the alarm to alert you if your per-minute heart beat goes above a specified level. The speed, distance and other performance data is also stored.

If you are really gung-ho, when skiing, climbing or running up and down a mountain trail, the Vertical mode indicates altitude, vertical speed, differences in altitude as you descend or ascend from point A to point B, and other information. Another handy option includes the finish mode, which indicates whether a specified pace is adequate or not, such as when, for example, you want to finish a 10 K race in a certain amount of time.