3. Calorie Counters
Some pedometers and GPS devices use your steps and speed to estimate the number of calories you burned. The most sophisticated of these programs let you enter information about your weight, which improves accuracy.
Some devices are better than others at making the calculation. "You usually get what you pay for," says Catherine G.R. Jackson, PhD, kinesiology professor at California State University, Fresno. "The more expensive units are typically more accurate."
Even the best give only an estimate.
4. Heart Rate Monitors
Your heart rate is the number of times your heart beats each minute, which goes up when you exercise. So heart rate monitors measure the intensity of your workout. Along with displaying heart rate in real time, many devices let you set a target heart rate and then alert you when you reach your target.
Heart rate monitors can help beginning exercisers tell if their workout is moderate or challenging. High-level athletes can use heart rate monitors to make sure they reach and remain in their target heart rate zone.
5. Activity Tracking
This feature lets you make notes about your workouts and other activities. If you’re a competitive athlete, an activity tracker is a great way to keep a detailed record of your training regimen. Activity trackers are also useful for setting goals and tracking progress.
Some programs let you enter information about how you feel, what you eat, and other data. They can help you spot patterns you might not otherwise notice, such as when you have the most energy during the day or when you tend to feel tired.
6. Computer Links and Social Networking
Many fitness devices let you download data to your computer into charts and graphs. You can often share that information.
Think of it as "wear, share, compare," Torgan says. "You can go for a run and then share your results, such as time and distance, with your friends."