While some people are fine just allowing their bodies to tell them when they're getting fitter or making progress at the gym, other people need to micro-manage their fitness goals. These are the people you're likely to see diligently checking their heart rates before, during and several times after a workout. What they may be doing is monitoring their "recovery heart rate," which can tell you what kind of shape you're in and how your ticker is doing.
Testing
Monitoring your recovery heart rate over time can help you get a read on your overall health and help you recognize potential problems. To test your recovery heart rate, first take your pulse while at rest, noting the number of times your heart beats in a minute to establish your baseline. Then start some strenuous exercise, working to exercise at 70 to 80 percent of your max. After a few minutes, stop and take your pulse. Two minutes later, take your pulse again. The difference between the during-exercise rate and the post-exercise rate is your recovery heart rate; the larger the number, the better.
Physical Condition
Generally, the better your physical condition, the faster your heart will recover to a "normal" rhythm after exercise. People who are in better shape can deliver more oxygen to their blood in a single breath, meaning they won't need as many respiratory cycles to get the same amount of oxygen to the blood. Since fit people's hearts weren't beating as quickly during the exercise, it follows that their heart rate will recover more quickly than people who are less fit. Additionally, better-fit people will tend to have a lower resting heart rate.
Cardiac Health
That "physical fitness" mentioned above is directly related to the heart. Your heart rate recovery is not just an indicator of overall physical fitness -- it's also an indicator of your heart health. As such, people who have slower heart rate recovery times may be at increased risk of cardiac-related death, according to studies published in TheHeart.org.
Intensity
The intensity of your exercise is also a factor in how quickly your heart recovers. When you're only pushing yourself to a fraction of your maximum output, your heart is not going to beat as fast. Naturally, that means your heart will return to its normal rate faster than if you would have pushed yourself harder. If you're going to be monitoring your recovery rate over time, you should be monitoring the rate following rounds of exercise that were relatively similar in intensity.
