Write an exercise Rx to improve patients' cardiorespiratory fitness

Using this framework, you can help patients realize intrinsic motivation that can facilitate progression through each stage, utilizing techniques such as motivational interviewing—so-called change talk—to increase self-efficacy.¹⁴TABLE 1¹⁵ provides examples of motivational interviewing techniques that can be used during a patient encounter to improve health behaviors, such as physical activity.

Table: Motivational interviewing: How to engage in change talk

Writing the exercise prescription

A patient who wants to increase their level of physical activity should be offered a formal exercise prescription, which has been shown to increase the level of physical activity, particularly in older patients. In fact, a study conducted in Spain in the practices of family physicians found that older patients who received a physical activity prescription increased their activity by 131 minutes per week; and compared to control patients, they doubled the minutes per week devoted to moderate or vigorous physical activity.¹⁶

FITT-VP. The basics of a cardiovascular exercise prescription can be found in the FITT-VP (Frequency, Intensity, Time, Type, Volume, and [monitoring of] Progression) framework (TABLE 2^17-19). For most patients, this model includes 3 to 5 days per week of moderate-to-vigorous physical activity for 30 to 60 minutes per session. For patients with established chronic disease, physical activity provides health benefits but might require modification. Disease-specific patient handouts for exercise can be downloaded, at no cost, through the American College of Sports Medicine (ACSM) “Exercise Is Medicine” program, which can be found at: www.exerciseismedicine.org/support_page.php/rx-for-health-series.

Table 2: Writing the cardiovascular exercise Rx

Determining intensity level. Although CPET is the gold standard for determining a patient’s target intensity level, such a test might be impracticable for a given patient. Surrogate markers of target intensity level can be obtained by measuring maximum HR (HRmax), using a well-known equation²⁰:

HRmax = 220 – age

which is then multiplied by intensity range:

• light: 30%-39%
• moderate: 40%-59%
• vigorous: 60%-89%

or, more preferably, by calculating the HR training zone while accounting for HR at rest (HRrest). This is accomplished by calculating the HR reserve (HRR) (ie, HRR = HRmax – HRrest) and then calculating the target heart rate (THR)²¹:

THR = [HRR × %intensity] + HRrest

Continue to: The THR calculation...