Physical Activity and Exercise Prescription

Introduction

Physical activity prescription is an underutilized tool for improving community health.[1] 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.[2]

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.

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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.[3] 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.[3]

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.[3] 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.[4] 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.[4]

Risk Profile Medical Clearance/Consultation Exercise Testing Conditions
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 maximal 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 to vigorous exercise Recommended Physician supervision recommended for submaximal or maximal exercise testing

Assessment of Exercise Capacity

Multiple protocols for measuring baseline exercise capacity exist. 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 moderate or low intensity exercise. Information about specific protocols for submaximal testing has assembled by Noonan & Dean.[5]

Exercise Prescription

Exercise prescription is based on 5 principles: type, duration, frequency, intensity, and volume. Type refers to mode of exercise training, with the main forms being aerobic (i.e. endurance training), resistance (i.e. strength training), 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 aerobic intensity include the following:

Each measure has guidelines for what parameters denote vigorous, moderate, and low intensity exercise. The following table offers a comparison of intensity across multiple measurement methods.[4][6][7]

Measurement Low Intensity Moderate Intensity Vigorous Intensity
Borg RPE scale (0-10) < 5 5-6 ≥ 7
HR max 50- 63% 64- 76% 77-93%
METS < 3 3-6 > 6
VO2 max 20-39% 40-59% 60-84%

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.[4]

Type Frequency Intensity Time/Duration Examples
Aerobic (Endurance) 5 days/week Moderate 30 minutes (for 150 minutes per week) Vigorous walking, jogging, swimming, hiking, cycling
Resistance (Strength) 2-3 days/week 60-70% of 1 rep max (novice), 40-50% of 1 rep max (sedentary person, older adult) 8-12 repetitions, 2-4 sets with 2-3 minutes rest in between Free weights, bodyweight exercise, calisthenics
Flexibility 2-3 days/week Until feeling of tightness. Hold 10-30 seconds, 2-4 times to accumulate 60 seconds per stretch Ballistic, static, dynamic, proprioceptive neuromuscular facilitation
Balance 2-3 days/week Has not been determined. 20-30 minutes Tai Chi, Yoga

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. In addition, the patient or client may have to work up to meeting the recommended 150 minutes per week.

Exercise Progression

Progression is way in which frequency, intensity, and duration of an exercise program are increased. Advancement of an exercise program should be incremental to encourage participant adherence and avoid injury. Recommendations for progressing aerobic exercise include increasing the duration of sessions 5 to 10 minutes every 1-2 weeks for the first 4-6 weeks.[4] Frequency and intensity can be progressed as tolerated. Overall volume should be monitored for adverse effects decreased if necessary.

In the case of resistance exercise, increasing repetitions is favored before increasing load. Once the maximum repetitions for a target range have been achieved, load can be increased by approximately 5% so that no more than the lower limit of repetitions can be performed.[8]

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Implications for Physical Therapist Practice

As experts in exercise across the life span, physical therapists stand to play an important role in promoting, prescribing and managing exercise programs. In addition to being a tool to remediate impairments, activity limitations, and participation restrictions, exercise prescription should also be used to improve the fitness and well being of patients and clients.

References

  1. Khan KM, Weller R, Blair SN. Prescribing exercise in primary care: ten practical steps on how to do it. British Medical Journal. 2011;343(d4141):806.
  2. World Health Organization. Global health risks: mortality and burden of disease attributable to selected major risks. Geneva: World Health Organization Press, 2009
  3. 3.0 3.1 3.2 Balady GJ, Chaitman B, Driscoll D, Foster C, Froelicher E, Gordon N, Pate R, Rippe J, Bazzarre T. Recommendations for cardiovascular screening, staffing, and emergency policies at health/fitness facilities. Circulation. 1998 Jun 9;97(22):2283-93.
  4. 4.0 4.1 4.2 4.3 4.4 American College of Sports Medicine. ACSM’s Guidelines for Exercise Testing and Prescription. 9th ed. Philadelphia (PA): Lippincott Williams & Wilkins; 2014.
  5. Noonan V, Dean E. Submaximal exercise testing: clinical application and interpretation. Physical therapy. 2000 Aug 1;80(8):782-807.
  6. Physical Activity Guidelines Advisory Committee. Physical Activity Guidelines Advisory Committee Report, 2008. Washington (DC); US Department of Health and Human Services; 2008.
  7. U.S. Department of Health and Human Services (1996). Physical Activity and Health: A Report of the Surgeon General. Atlanta GA. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion.
  8. Center for Health Protection. Exercise Prescription Doctor's Handbook. Hong Kong: Department of Health; 2012