The success of cardiovascular fitness equipment in promoting improvements in aerobic fitness and adherence depends upon the proper merging of both the physical and psychological realms. Research has shown that regular use of exercise machines such as treadmills, stair climbers, rowers and stationary cycles can improve the health, fitness and mental well-being of an exerciser. A method of increasing the likelihood that people will exercise regularly is to provide feedback to the exerciser about two important issues: workout performance and caloric expenditure.

Most recently manufactured exercise machines have a lighted electronic display panel that summarizes information about the user's speed, heart rate, training zone, calories burned, power and work output, and evaluation of performance compared to the average user. These machines can also be programmed by the user to set the parameters of the exercise, such as the percent of the target heart rate (THR) and the workout profile. Typically, these control panels generate sounds or flash lights at various stages of exercise and display images of the exercise program set by the user, such as pictorial views of climbing hills or traveling across a landscape.

Untrained persons beginning exercise, individuals training for adult fitness and trained athletes can all benefit from visual feedback. A common complaint of untrained people who begin exercising on a stationary piece of equipment is that the activity is boring. Providing users with information about their work, power, caloric expenditure and a graphical view of their progress during exercise heightens interest in completing the workout, and increases the likelihood that they will adhere to a regular exercise schedule.

Intermittent sounds such as beeping or flashing lights at various stages of the workout keep the beginning exerciser focused on the task and guide the exerciser through each workout stage. Individuals exercising for adult fitness and health can use visual feedback to achieve fitness standards set by the American College of Sports Medicine. Visual feedback also allows the user to maintain an exercise intensity within a recommended target heart rate zone for a selected time.

Likewise, trained individuals benefit from visual and audible feedback. For example, motivated athletes typically use feedback to compare performance from one session to the next, often using total distance, peak speed or intensity achieved as parameters. This enables athletes to monitor the progress of their performance over time and achieve long-term goals.

In all cases, fitness machine feedback provides positive reinforcement about the achievement of an exercise task. Feedback is a corrective device that is motivational, makes the workout more interesting and helps the exerciser stay on course for success.

Part of the visual feedback provided by fitness machines is the caloric expenditure per workout session. A point of contention for equipment manufacturers that market similar pieces of fitness equipment, such as treadmills, stair climbers or cycles, is that for a the same user, the absolute caloric expenditure displayed for a standardized exercise session will not necessarily be the same among models. In fact, there may be as much as a 5 to10 percent difference in displayed caloric expenditure between machines. Why does this occur, and why is it so difficult to accurately assess caloric expenditure?

Exercise machines may estimate caloric expenditure based on one or several assumptions: fitness levels are the same between users; for a given body weight, caloric expenditure is the same between users; the skill level for the exercise is equal among users; the person is exercising at the exact same intensity during the entire workout; and caloric expenditure is the same for men and women. Each of these factors contributes to variations in calorie counting between fitness machines. As skill levels increase, fewer calories are used for a specified exercise task. The machine, however, does not factor in skill and calculates calories based on an assumed fitness level.

Machines that do not allow the individual to type in body weight base the caloric expenditure on an average sized male (70 kg). This would serve to overestimate expenditure for people smaller than this average and underestimate expenditure for larger people. Machines that factor in the user's weight certainly provide a better assessment of caloric expenditure, but accuracy of this assessment could be further improved if body composition (amount of fat and muscle weight contained in total body weight) were also factored. For example, a muscular person expends more calories compared to a less muscular person for the same task. The net result is variance in calorie counting among machines.

Calculated caloric expenditure values may be helpful in getting rough estimates of calories burned and are helpful in monitoring progress of an individual's exercise program, particularly if regular exercise is performed on the same piece of equipment.