Physical Activity and Exercise Prescription

Introduction

Physical activity prescription is an underutilized tool for improving community health. In the right dose, physical activity can help to prevent, treat, and manage a range of chronic health conditions that increasingly impact the quality of life and physical function of individuals on a global scale.

Safe and effective exercise prescription requires careful consideration for the target individual's health status, baseline fitness, goals and preferences. Several national and international organizations provide clinicians and allied health professionals with guidelines for how to screen, assess, and, when appropriate, prescribe exercise for the benefit of their patients/clients.

Pre-exercise Screening

Before starting an physical activity program, the American College of Sports Medicine (ACSM) and the American Heart Association (AHA) recommend screening to identify cardiovascular risk factors. Screenings help mitigate the risk for adverse responses to exercise, as even moderate physical activity can trigger cardiac events in individuals who are largely sedentary.

With this in mind, two instruments are recommended to facilitate the risk screening process for fitness professionals. The most commonly used questionnaire is the PAR-Q, followed by the Fitness Facility Pre-participation Screening Questionnaire. The PAR-Q is a brief 7 item questionnaire that uses a yes/no answer format to identify personal risk factors. In comparison, the Fitness Facility Pre-participation Screening Questionnaire is slightly longer and captures more detailed information about cardiovascular symptoms.

Screening results in stratifying prospective participants into 3 levels of risk: low, moderate, and high. Low risk individuals are men younger than 45 and women younger than 55 with no more than one cardiovascular risk factor. Moderate risk stratification pertains to men over 45 and women over 55 with 2 or more risk factors. The highest risk category includes any individual with known cardiovascular, pulmonary or metabolic disease or who demonstrates signs or symptoms of cardiovascular disease. Signs and symptoms the automatically lead to high risk stratification include:

• Pain, discomfort in the chest, neck, jaw, arms, or other areas that may be due to ischemia.
• Shortness of breath at rest or with mild exertion.
• Dizziness.
• Orthopnea or paroxysmal nocturnal dyspnea.
• Ankle edema.
• Palpitations or tachycardia.
• Intermittent claudication.
• Unusual fatigue or shortness of breath with usual activities.
• Known heart murmur.

From this information, a decision about the need for medical clearance/consultation can be made prior to further testing. Below is a summary of medical clearance and testing recommendations based on  the risk level of the individual and the intensity of exercise in which he or she wishes to participate.

+Low-risk individuals & vigorous exercise/ Not necessary/ Submaximal or maximal testing, no physician present, emergency procedures in place

+Moderate-risk individuals & moderate exercise/ Not necessary/ Submaximal or max testing, no physician present, emergency procedures in place

+Moderate-risk individuals & vigorous exercise/ Recommended/ Physician supervision recommended for maximal exercise testing

+High-risk individuals & moderate/vigorous exercise/ Recommended/ Physician supervision recommended for submaximal or maximal exercise testing

Assessment of Exercise Capacity

There are multiple protocols for measuring baseline exercise capacity. For aerobic capacity, exercise testing falls into 2 categories: maximal and submaximal testing. Maximal testing is reserved for assessing the capacity of individuals who participate in vigorous exercise. Submaximal testing is adequate for individuals who will only participate in low or moderate intensity exercise. Information about specific protocols has assembled by [article authors with citation].

Exercise Prescription

Exercise prescription is based on 5 principles: type, duration, frequency, intensity, and volume. Type refers to mode of exercise training, with main forms being aerobic (endurance), resistance (strengthening), flexibility, and balance. The length and number of exercise sessions performed within a given time frame, are described by duration and frequency, respectively. Intensity is defined as the level of effort being exerted by the participant and can be measured in a variety of ways. Common measures of intensity include the following:

• Borg scale [hyperlink]
• Target heart rate [hyperlink]
• METS [hyperlink]
• Maximum oxygen consumption (VO2 max)

Each measure has guidelines for what parameters denote vigorous, moderate, and low intensity exercise. The table below compares intensity across multiple measurement methods.

[TABLE]

+Vigorous intensity exercise: "On an absolute scale, vigorous intensity refers to activity that is performed at 6.0 or more times the intensity of rest for adults and typically 7.0 or more times for children and youth. On a scale relative to an individual’s personal capacity, vigorous- intensity physical activity is usually a 7 or 8 on a scale of 0–10." [WHO Comm]; Vigorous exercise has been described as a substantial cardiovascular challenge or an intensity greater than 6 metabolic equivalents (METs) (21 ml/kg/min of oxygen consumption), or at greater than 60% of the VO2max (10). [cardio JOSPT]

+Moderate intensity exercise: "On an absolute scale, moderate intensity refers to activity that is performed at 3.0–5.9 times the intensity of rest. On a scale relative to an individual’s personal capacity, moderate-intensity physical activity is usually a 5 or 6 on a scale of 0–10." [WHO Comm]; Moderate intensity is described as activities between 3 and 6 METs. [cardio JOSPT]

+Low intensity exercise: Activities that are less intense than moderate are classified as low intensity. However, in deconditioned individuals with severely compromised aerobic capacity, slow walking may actually be considered moderate or vigorous exercise, as an individual may be working near maximal capacity.

The final principle of exercise prescription is volume. Volume is a sum of the intensity, frequency, duration, and longevity of a physical activity program.

Recommendations regarding frequency, time, and intensity have been established for each type of exercise training.

[TABLE] [ACSM]

Type/Frequency/Intensity/Time/Type

+Cardiorespiratory/ 5d a week/ Moderate/ 30 min/ Vigorous walking, jogging, swimming, hiking, cycling

+Strength/ 2-3d a week/ 60-70% of 1 RM (novice), 40-50% of 1 RM (older adult or sedentary person), 8‒12 repetitions, 2–4 sets with rest of 2–3 min between each set/ Involving all point of feeling tightness/ Hold stretch for 10–30 s, repeat each flexibility exercise 2–4 times/ Involving all major muscle-tendon units. Can be ballistic, static, dynamic, or proprioceptive neuromuscular facilitation.

+Balance/ 2-3d a week/ Has not been determined/ 20-30min/ Tai Chi, Yoga, Qigong

The way in which these recommendations are applied depends on multiple factors. In developing a program prescription, health professionals must consider fitness level, fitness goals, exercise preferences, equipment availability, and other personal factors that may impact participation. For example, if a patient or client is starting at a low level of fitness, an initial program may include low to moderate intensity, aerobic exercise that the individual enjoys and fits his or her time schedule to encourage adherence.

Exercise testing provides a concrete starting point for developing a prescription. The AHA & ACSM use 4 classes to provide guidelines for supervision and measures of intensity.

TABLE] [AHA/ACSM recs]

Class & description/exercise prescription

>>Class A: apparently healthy low to moderate risk/ intensity via RPE alone or target heart rates

>>Class B: presence of known, stable cardiovascular disease with low risk for vigorous exercise but slightly greater than for apparently healthy persons; moderate to high risk/ intensity via target heart rates and perceived exertion ratings

>>Class C: Those at moderate to high risk for cardiac complications during exercise and/or who are unable to self-regulate activity or understand the recommended activity level; high risk, supervised exercise only/ see class B

>>Class D: Unstable conditions with activity restriction; high risk/ exercise not recommended

-Compenents of a Single Exercise Session [Phys Handbook]

Warm-up

Conditioning

Cool down

Stretching

-Progression

Duration: 5 to 10 minutes every 1-2 weeks for the first 4-6 weeks

Frequency and Intensity: as tolerated

Volume: monitor for adverse effects (adjust downward if not well tolerated)

-Adoption and Maintenance

Exercise adherence may decrease if exercise intensity is too high, particularly the first 4 to 6 weeks (ACSM 1995).

Implications for Physical Therapist Practice

-Exercise prescription in primary care is lacking.