Bushman, Barbara A. Ph.D., FACSM
Q: WITH ALL THE DIFFERENT EXERCISE RECOMMENDATIONS AND PROGRAMS REPORTED IN THE MEDIA, WHAT IS ACSM’S STANCE ON EXERCISE PRESCRIPTION FOR HEALTHY ADULTS? I’M A PERSONAL TRAINER AND WOULD LIKE TO HAVE GUIDANCE FOR DEVELOPING INDIVIDUALIZED EXERCISE PRESCRIPTIONS.
A: Many sources of information related to exercise are reported by the media — some are based on personal opinions or gimmicks, whereas others have scientific backing. Previous publications in the latter category include the 1995 U.S. Centers for Disease Control and Prevention/American College of Sports Medicine (ACSM) public health recommendation (5), the U.S. Surgeon General’s Report in 1996 (7), the American Heart Association and ACSM recommendations in 2007 (3,4), and the 2008 Physical Activity Guidelines for Americans (6). These publications have been pivotal relative to defining how much and what type of exercise is needed to improve health and well-being.
Your question, focused on developing exercise prescriptions for your clients, also is addressed in a new position stand by ACSM (2), released in July 2011, “Quantity and Quality of Exercise for Developing and Maintaining Cardiorespiratory, Musculoskeletal, and Neuromotor Fitness in Apparently Healthy Adults: Guidance for Prescribing Exercise.” The purpose of this position stand is to provide evidence-based recommendations, supported by published studies, for health and fitness professionals to use when developing individualized exercise prescriptions for apparently healthy adults. For each of the recommended exercise components, health benefits are supported by scientific studies (see Table 1 for some selected examples) (2).
To paraphrase the conclusion of the position stand, ACSM’s recommendation for apparently healthy adults of all ages is to reduce time spent in sedentary activity and to adopt a comprehensive exercise program including cardiorespiratory, resistance, flexibility, and neuromotor exercises (see Table 2 for a summary of the detailed recommendations) (2). The current edition of ACSMs Guidelines for Exercise Testing and Prescription (1) also emphasizes these same four fitness components.
The position stand provides additional clarification on a number of areas (2), and the following list summarizes a few of these points of interest:
* What is the intensity threshold for improving cardiorespiratory fitness?
The overload principle suggests that a challenge or stimulus must be placed on the body for an improvement to occur. Although the concept of a minimal intensity threshold is supported, differences in an individual’s initial level of fitness and conditioning makes this idea difficult to universally apply. Specifically, the needed exercise intensity seems to vary depending on fitness level with lower intensity thresholds for the less fit (e.g., 45% maximal oxygen uptake, V˙O2max or ~60% maximum heart rate, HRmax) and higher intensity for higher fit (e.g., 70% to 80% V˙O2max or ~80%–85% HRmax for moderately trained and even up to 95% to 100% of V˙O2max or HRmax for well-trained athletes).
* How much exercise is needed to maintain the benefits of exercise?
If an exercise program is terminated or if the training level is reduced, the positive adaptations will decrease at varying rates over time. For cardiorespiratory fitness, various physiological changes occur as soon as 1 to 2 weeks after training ceases. Some research reviewed in the position stand suggests that more exercise is required to improve than to maintain cardiorespiratory fitness, although no specific formula is available to determine the dose response. For resistance training, as little as one moderate-to-hard session per week is likely sufficient to maintain muscular strength, functional performance, and other health benefits. Note that intensity seems to be important in maintaining the benefits of resistance training. Improvements in joint range of motion because of stretching and flexibility exercises reverse within 4 to 8 weeks of stretching cessation. Decreasing the frequency of stretching has not been studied extensively, but 2 to 3 days per week seemed to promote maintenance of range of motion achieved from previous daily stretching.
* Does the pattern of exercise make a difference?
Accumulating moderate-intensity exercise in bouts of 10 minutes or more is one option to achieve the daily goal of at least 30 minutes per day. Shorter bouts may lead to both fitness and health benefits, especially if the individual is sedentary, although the amount of research in this area is limited. On the other end of the spectrum are the “weekend warriors,” who engage in a large total volume of activity on a limited (1 to 2) number of days per week. Few studies have examined this pattern, but the possibility of benefit exists for people free of meaningful preexisting cardiovascular risk (compared with being sedentary). For those with cardiovascular risk factors, physical activity on a regular basis throughout the week is likely needed to improve their risk factor profile.
* What can be said about sedentary behavior?
Sedentary behavior includes sitting and expending low levels of energy (e.g., computer use, watching television, traveling by car, sitting at a desk). Negative health outcomes associated with sedentary pursuits include an elevated risk for heart disease, premature death, and depression; increased waist circumference; elevated blood pressure; and other undesirable changes in various biomarkers for chronic disease. Even among those who meet the current physical activity guidelines, sedentary behavior can be detrimental. The position stand recommends breaking up sedentary activities with short bouts of activity (e.g., standing, walking) to help attenuate adverse effects.
* Are pedometers a good way to prescribe exercise?
Although pedometers are effective in promoting physical activity and even modest weight loss, they are inexact with regard to indexing exercise volume. In particular, factors related to the quality of steps (e.g., speed, grade) are not available for review as part of the feedback provided. Various studies noted in the position stand suggest that fewer steps per day than the often used 10,000 steps per day target may be sufficient to meet the exercise recommendations previously noted. Moderate-intensity exercise seems to correspond to 100 steps per minute, although this is a rough estimate. Using this approximation, along with the current recommended duration of at least 30 minutes of exercise per day, may be one way to incorporate pedometers into an exercise prescription (e.g., 100 steps per minute for a 30-minute exercise session).
* When should stretching be performed?
Flexibility exercises will be most effective when the muscle is warmed through either light-to-moderate cardiorespiratory or muscular endurance exercise or through passive methods such as heat packs or hot baths. Whether stretching should be done before or after the conditioning phase of an exercise session has been and continues to be an area of research and may depend on the focus of the session (e.g., strength or power performance may be hampered with pre-event stretching, whereas recreational sports like dancing may be benefited). More research is needed to definitively answer this question. For individuals focused on a general fitness program, including flexibility exercises after their cardiorespiratory or resistance training session, or as a stand-alone program, is recommended in the position stand.
* How can risks associated with exercise be reduced?
Although the benefits of exercise are well documented, the risk of heart or musculoskeletal complications is increased slightly during exercise compared with a similar time at rest. The type and intensity of exercise seems to be related to injury more so than the volume (e.g., walking and other moderate-intensity activities have a lower risk of musculoskeletal injury than running or competitive sports). Although research is still needed to substantiate effectiveness, common methods to reduce injury include using warm-up and cool-down periods and gradually progressing amount and intensity. Maintaining a regular exercise routine along with knowledge of the signs and symptoms of heart disease are important for safe participation as well. Fitness professionals are encouraged to use health assessments or medical history questionnaires (e.g., Physical Activity Readiness Questionnaire) to identify factors that are known to increase risk. Of course, consulting with medical professionals also is appropriate in some circumstances (1).
The position stand contains a wealth of information and supports a comprehensive program of exercise for apparently healthy adults, including cardiorespiratory, resistance, flexibility, and neuromotor exercises. Although a world where all individuals engage in a comprehensive exercise program would be ideal, exercise of lower volume or an exercise program that does not contain all the exercise components will provide some benefit, especially for habitually inactive individuals. Recall, some activity is better than none, and more, up to a point, is better than less (1).
The value of the fitness professional is stated clearly in the summary for the position stand (2), “The supervision of an experienced fitness professional can enhance adherence to exercise and likely reduces the risk of exercise in those with elevated risk of adverse [coronary heart disease] events. Adults, especially novice exercisers and persons with health conditions or disabilities, likely can benefit from consultation with a well-trained fitness professional.” Because exercise is of benefit only if a person does the activity, fitness professionals will need to reflect on individual responses and adjust individual exercise prescriptions accordingly.
(Note: examples of specific exercises and progressive programs for beginners, intermediate, and established exercisers can be found in ACSM’s Complete Guide to Fitness & Health, Human Kinetics, 2011.)
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1. 1. American College of Sports Medicine. ACSM’s Guidelines for Exercise Testing and Prescription. 8th ed. Philadelphia (PA): Lippincott Williams & Wilkins; 2010, 380 p.
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. American College of Sports Medicine Position Stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: guidance for prescribing exercise. Med Sci Sports Exerc
3. 3. Haskell WL, Lee IM, Pate RR, et al
. Physical activity and public health: updated recommendation from the American College of Sports Medicine and the American Heart Association. Med Sci Sports Exerc
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. Physical activity and public health in older adults: recommendation from the American College of Sports Medicine and the American Heart Association. Med Sci Sports Exerc
5. 5. Pate RR, Prate M, Blair SN, et al
. Physical activity and public health. A recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. JAMA
6. 6. U.S. Department of Health and Human Services Web site [Internet]. 2008 Physical Activity Guidelines for Americans
, 2008. Atlanta (GA):USDHHS; [cited 2011 August 2]. Available fromml: http://www.health.gov/paguidelines
7. 7. U.S. Department of Health and Human Services Web site [Internet]. Physical Activity and Health: A Report of the Surgeon General
. Atlanta (GA):U.S. Department of Health and Human Services; 1996. [cited 2011 August 2]. Available fromml: http://www.cdc.gov/nccdphp/sgr/index.htm