Since Linda started using her Fitbit, she can often be seen pacing the floor while talking on the telephone or watching TV. She is happy with her activity tracker and feels that it is helping her meet her health and fitness goals.

If you haven’t heard of Fitbit, Jawbone, Garmin or any of the other activity trackers, you are probably in the minority. It’s now estimated that one of five Americans wears a fitness tracker. And a good number of these persons have rather optimistic views of what these gadgets can do for them.

These electronic trackers are basically upgraded versions of pedometers, and early versions such as the original Fitbit introduced in 2009 were clipped to the waist. Compared to pedometers which cost $15 to $20, these devices are expensive, running from $60 to $250 or more. They do, however, have greater tracking ability and include software that enables you to connect with your computer or smart phone.

As activity trackers become more popular, the basic appeal apparently is the ability to visualize your activity on charts and graphs and monitor your progress from day to day and week to week. If you wish, you can use social media to compete with friends.

Two popular and highly rated devices are the Fitbit Charge HR and the Garmin Vivosmart HR. The features are roughly the same: measurement of daily steps, miles traveled, calories consumed, floors climbed, sleep quality and a continuous reading of heart rate. Unlike sports watches with heart rate monitors, such as the Polar FT1 and 4, these trackers don’t require a chest strap.

At this price level (about $150), you can expect to get a watch and activity readout on the wrist band as well as on your smart phone or computer.

In addition, the software tracks active minutes and gives a summary of each workout, charting time, calories consumed and average beats per minute.

At a lower price point (about $100), trackers such as the Jawbone UP2 and the Fitbit Flex have most of the above tracking features except heart rate. The information can be accessed through your computer or smart phone but not on your wrist.

At a higher price point (about $250), devices such as the Fitbit Surge and the Garmin Vivoactive offer a full-size watch plus GPS tracking to go with all of the other features.

The GPS gives an accurate tracking of distance. Without it, you should realize that an activity tracker gives you an approximation of distance based on steps taken and heart rate.

For step tracking, nearly all wrist devices base their calculations primarily on arm movement. If you wave your arms without walking, you get credited with steps. If you push a grocery cart, moving your legs but not your arms, you get very little credit. By comparison, the less expensive Omron pedometer, which attaches to your belt, is more likely to give you an accurate tracking of steps.

Jack was particularly pleased with the sleep information he received from his device. If he woke at 3 a.m. for a bathroom trip, a red line indicated the interruption. White lines indicated when his sleep was restless. And he was happy to discover that these white lines occurred more frequently in the morning as he was preparing to wake up rather than in the middle of deep sleep.

Such information is no substitute for a sleep study to diagnose sleep disorders, but it might indicate the need for such a study if the restless lines were too prevalent.

Heart rate is clearly an important indicator of health and fitness. But, again, it’s important to remember that the activity tracker is not a medical instrument.

A resting heart rate that gets lower over time is a sign that the heart is getting stronger and more efficient. And the software for most wrist monitors will allow you to see this kind of progress.

The major health benefit of an activity tracker is the increased motivation to be active and to maintain healthy habits, including good sleep.

The possibilities are virtually endless, and new wrinkles are being added all the time. Are activity trackers merely expensive toys, or do they provide real health benefits? There is no question that Americans need to be more active, and if these devices motivate people to take more steps and climb more stairs, they may be worth the expense.

How long will the motivation last? And will the couch sitters who stand to benefit the most ever succumb to the temptation? It’s too soon to tell.

Abby Helnore is the Director of Health and Wellness at Bay Area Medical Center, Marinette.