This course expires on Dec. 17, 2009.
The goal of this continuing education offering is to provide nurses with information on updated physical activity recommendations. After reading this article, you will be able to:
1. Discuss health benefits of regular physical activity.
2. Describe examples of aerobic activity.
3. Discuss health benefits of muscle-strengthening activity.
You can earn 1 contact hour of continuing education credit in three ways: 1) For im-mediate results and certificate, go to www.advanceweb.com/lnurses. Grade and certificate are available immediately after taking the online test. 2) Send this answer sheet (or a photocopy) along with the $8 fee (check or credit card) to ADVANCE for Nurses, Learning Scope, 2900 Horizon Dr., King of Prussia, PA 19406. 3) Fax the answer sheet to 610-278-1426. If faxing or mailing, allow 30 days to receive certificate or notice of failure. A certificate of credit will be awarded to participants who achieve a passing grade of 70 percent or better.
Merion Publications Inc. is an approved provider of continuing nursing education by the Pennsylvania State Nurses Association (No. 008-0-07), an accredited approver by the American Nurses Credentialing Center's Commission on Accreditation. Merion Publications Inc. is also approved as a provider by the California Board of Registered Nursing (No. 13230) and by the Florida Board of Nursing (No. 3298).
In 1995, the CDC and the American College of Sports Medicine (ACSM) published physical activity recommendations for healthy adults. They stated, "All people over the age of 2 years should accumulate at least 30 minutes of endurance-type physical activity of at least moderate intensity on most, preferably all, days of the week." The aim was to encourage more Americans to exercise.
Unlike earlier exercise guidelines, this recommendation emphasized a lifestyle approach to increasing physical activity. Common activities, such as brisk walking, taking the stairs instead of the elevator, and engaging in more house and yard work were now considered effective ways to gain health benefits. Science showed moderate amounts of daily physical activity reduced risk of chronic disease and premature mortality.
Today, some adults still believe you must exercise to exhaustion to gain benefits. Others believe light physical activity provides enough health benefits. In August 2007, the ACSM and the American Heart Association (AHA) released updated physical activity guidelines aimed at clarifying earlier recommendations. These recommendations are more comprehensive and include knowledge attained since the 1995 recommendations were published.
Health benefits of regular physical activity noted in the updated guidelines include reduced risk of cardiovascular disease, thromboembolic stroke, hypertension, type 2 diabetes, osteoporosis, obesity, colon cancer, breast cancer, anxiety and depression.
The 2007 ACSM/AHA recommendations stated, "To promote and maintain health, all healthy adults ages 18-65 years need moderate-intensity aerobic (endurance) physical activity for a minimum of 30 minutes on 5 days each week or vigorous-intensity aerobic physical activity for a minimum of 20 minutes on 3 days each week."
This guideline is basically the same as the 1995 one but more specific. For example, the term "physical activity" is described as aerobic activity. Examples of aerobic exercise include brisk walking, biking and jogging. This type of activity consists of continuous rhythmic movements of large muscle groups that can be sustained for a period of time. Aerobic activity increases the heart and breathing rates and trains the heart, lungs and muscles to utilize oxygen more efficiently. Aerobic exercise also is referred to as endurance exercise because it increases one's energy and capacity for work.
Both moderate- and vigorous-intensity aerobic activities are incorporated into the new guidelines, and the minimum frequency and duration of exercise is clarified. Moderate-intensity exercise is described as generally equivalent to walking at 3-4 miles per hour on a flat surface. Aerobic activities of daily living that would meet moderate-intensity levels include washing windows, sweeping floors and golf (walking and pulling cart). Moderate-intensity physical activity is described as producing a noticeable increase in heart rate and breathing. Moderate-intensity physical activity also is generally described as working hard enough to raise heart rate and breathing, yet able to carry on a conversation.
Activities such as casual walking, shopping, cooking and self-care are considered light activities that do not meet the intensity level needed to promote health. The amount of physical activity considered necessary is in addition to routine activities of daily living that require low levels of exertion. This was implied in the original recommendations, although not directly communicated.
The new guidelines address vigorous-intensity activity due to some adults' preference for this type of activity and the evidence of the benefits of high-intensity exercise. Since the time needed to exercise is related to intensity and frequency, less time (20 minutes, 3 times/week) is needed when exercising vigorously, compared to the time needed (30 minutes, 5 times/week) when exercising at a moderate pace.
Examples of vigorous physical activity include very brisk walking (4.5 mph), jogging (5 mph) and running (7 mph). Biking at 12-14 mph, cross-country skiing and singles tennis are vigorous recreational activities. Hiking steep grades, shoveling sand and bailing hay also are vigorous activities. This level of activity produces rapid breathing and a substantial increase in heart rate.
The new guidelines specify how to combine moderate-intensity activity with vigorous activity to meet the recommended level of activity. For individuals who enjoy varying intensities, vigorous exercise on 2 days and moderate-intensity exercise on 2 days meets the minimum dose needed to gain health benefits. Combining activities is based on the total amount (intensity, duration, frequency) of activity performed each week.
A method of determining energy expenditure when combining activities of various intensities is outlined in the new recommendations. The calculations are based on MET (metabolic equivalent) levels and assign an intensity value to a specific activity.
One MET: equivalent to sitting quietly
Activities of less than three METs: light
Activities between three and six METs: moderate
Activities greater than six METs: vigorous
In addition to the formula for determining daily and weekly energy expenditure, the range of MET/minutes/week needed to attain health benefits is provided.
P>Mixing It Up
The original recommendations introduced the concept of accumulating short bouts of physical activity over the course of the day. The new guidelines state intermittent bouts of exercise are just as effective as a single bout, but the activity must be done in sessions of 10 minutes or more.
For example, 30 minutes of moderate-intensity physical activity could include a 10-minute brisk walk to the train in the morning, 10 minutes of gardening with a shovel in the afternoon and 10 minutes on a stationary bike (10-12 mph) in the evening. The updated guidelines also state few routine activities of contemporary life, such as walking to the car, are conducted at a moderate intensity for at least 10 minutes.
The type, frequency, intensity and duration of physical activity recommended is the minimum amount needed to produce health benefits, but the updated guidelines explicitly state gains are dose-dependent. Exceeding minimum recommendations produces a higher level of fitness, helps prevent unhealthy weight gain and further reduces risk of disease. In other words, more physical activity produces more benefits and the amount of physical activity needed depends on an individual's needs and goals.
Other agencies over the past decade have released activity guidelines that could be interpreted to be in conflict with the current "minutes per day" recommendation, but differences appear because they are intended for different groups and may be relevant to individuals who are overweight or obese.
The 1995 recommendations mentioned the importance of muscular strength and endurance. The 2007 recommendations, for the first time, include specific guidelines for muscle-strengthening activity. The following statement is part of the core recommendation for physical activity: In addition to aerobic activity, every adult should perform activities that maintain or increase muscular strength and endurance a minimum of 2 days each week to promote and maintain good health and physical independence.
Resistance training or muscle-strengthening exercise refers to performance of muscle contractions against a resistance greater than that to which the muscle is accustomed. The new guidelines point to recent evidence showing resistance training not only enhances muscular strength and endurance but also provides health benefits and reduces all-cause mortality.
Benefits of muscle-strengthening include an increase in bone formation in young adults, slower bone loss in middle age, and lower risk of osteopenia, osteoporosis and bone fracture. Strength training also has a positive effect on glucose metabolism. Resistance training increases glucose uptake and insulin sensitivity in skeletal muscle. Studies now show muscular strength is inversely related to the metabolic syndrome.
Other health benefits of strength training are cited in an AHA Scientific Statement on resistance exercise, which was released in July 2007. Increased muscle mass leads to an increase in resting metabolic rate, which assists in weight control. More calories are burned around the clock with a gain of 1 kg in muscle mass, increasing energy expenditure by about 21 kcal/day.
Resistance training contributes to a reduction in central obesity (visceral adipose tissue) and is considered a complement to aerobic exercise in controlling other risk factors for heart disease, including dyslipidemia and high blood pressure.
The updated ACSM/AHA guidelines recommend performing 8-10 muscle-strengthening exercises on 2 or more nonconsecutive days per week using the major muscle groups. The resistance used should result in volitional fatigue (i.e., inability to continue using correct form and technique) with one set of 8-12 repetitions of each exercise. Single-set versus multiple-set programs are recommended because they provide nearly the same relative improvements in strength, are highly effective and less time-consuming, and promote adherence.
Since physical conditioning is specific to the muscle group being trained, training regimens should involve the major muscle groups. An example of a set of exercises that includes all the major muscle groups includes:
pull-down (upper back);
lower back extension;
leg curl (hamstrings); and
Current ACSM guidelines also recommend alternating upper-body exercises with lower-body exercises to allow adequate rest between exercises. Eight to 10 exercises can be accomplished in 15-20 minutes and should follow aerobic training to ensure adequate warm-up.
Other safety guidelines related to resistance training include practicing good technique. Exercises should be performed through a full range of motion at a moderate-to-slow, controlled speed. Breath-holding and straining (Valsalva maneuver) should be avoided. Exhaling during the contraction or exertion phase of the lift and inhaling during the return to the start position is recommended. Weights and exercise tubes/bands should not be gripped too tightly, as this produces an increased blood pressure response.
As strength increases, training load can be gradually increased. When the repetition range can be accomplished comfortably, increase the resistance by approximately 2-5 pounds for the upper body and 5-10 pounds for the lower body.
Strength training can be performed in a gym using weight machines and free weights. Effective low-cost approaches that can be performed at home and allow for gradual progression in resistance include calisthenics, resistance bands/tubes, dumbbells and wrist weights.
Physical Activity for Older Adults
The ACSM and AHA also released a companion paper that provides exercise guidelines for older adults (men and women age 65 and older and adults ages 50-64 with clinically significant chronic conditions and/or functional limitations). The recommendations are similar to those for healthy adults with a few differences.
The aerobic activity recommendation is the same with added reference for gauging intensity. Moderate intensity is described as a 5 or 6 on a 10-point scale, with sitting as 0 and all-out effort as a 10. Vigorous intensity is described as a 7 or 8.
What constitutes moderate intensity for some adults may feel light or hard to others. Many months of activity at less than recommended levels may be appropriate for some inactive older adults and adults with certain health conditions. Taking a stepwise approach using shorter bouts of activity (greater than or equal to 10 minutes) is appropriate.
Muscle-strengthening exercise also is recommended for older adults and considered essential in preventing sarcopenia or age-relatedloss of muscle mass. Resistance training helps older adults in maintaining functional capacity, independence and quality of life.
Resistance training improves physical function by increasing stride velocity, stride length, stair-climbing power and balance. It decreases stride duration, chair rise time, postural sway, and timed up and go. Ultimately, it reduces risk of falls and the disability associated with aging.
Being able to walk longer and faster also enables older adults to participate more fully in aerobic activity. In addition, having stronger skeletal muscles benefits heart health by decreasing hemodynamic stress to a given load. Activities of daily living such as emptying the washing machine, carrying groceries, and taking out trash become easier and evoke a lower rate-pressure product (i.e., heart rate times systolic blood pressure, an indirect index of myocardial oxygen demand).
Weights for Older Adults
The ACSM/AHA recommendation for strength training for older adults differs from that of younger adults in the number of repetitions (reps) per set. A resistance or weight should be used that allows 10-15 reps for each exercise versus the 8-12 reps recommended for younger adults. More reps per set with less resistance lower the relative effort and decrease the risk of injury and likelihood of breath-holding and straining.
Initial weights for older adults can be light and gradually increased. The level of effort should be moderate to high. A 5-6 on a 10-point scale where no movement is 0 and maximal effort is a 10 is considered moderate and a rating of 7 or 8 is high. Higher levels of activity for older adults are appropriate for selected older adults with sufficient fitness, experience and motivation.
Flexibility exercise to maintain joint range of motion is specifically recommended for older adults. Flexibility training or stretching should be performed for at least 10 minutes on at least 2 days per week. Ideally, flexibility training should be done 5-7 days per week and on all the days aerobic and/or muscle-strengthening activity occurs.
Stretching should be preceded by a warm-up to raise muscle temperature. Stretches should be performed slowly with control and held for 10-30 seconds. All major groups should be stretched, and stretching should be done to the point of tightness, not pain. Stretches are typically repeated 2-4 times.
Balance exercise, performed 3 days per week, is recommended for community-dwelling older adults with substantial risks of falls. The recommendation applies only to community-dwelling older adults because of insufficient data in long-term care and hospital settings.
Reducing sedentary behavior in older adults is a priority. Management of an existing chronic condition also needs to be considered. Risk management strategies to prevent injuries and activity-related adverse events are particularly important. Combining preventive and therapeutic recommendations for older and younger adults and relying on healthcare and community resources, such as outpatient cardiac and pulmonary rehab, and exercise classes designed for individuals with arthritis should be an important part of the activity plan.
Encouraging increased participation in physical activity and acting as role models to a largely sedentary population is the responsibility of all healthcare professionals.
American College of Sports Medicine. (2006). ACSM's guidelines for exercise testing and prescription (7th ed.). Philadelphia: Lippincott Williams and Wilkins.
American Heart Association. (2007). Resistance exercise in individuals with and without cardiovascular disease: 2007 update. Retrieved Nov. 29, 2007 from the World Wide Web: http://www.americanheart.org/presenter.jhtml?identifier=3050002
Haskell, W.L., et al. (2007). Physical activity and public health: Updated recommendation for adults from the American College of Sports Medicine and the American Heart Association. Retrieved Nov. 29, 2007 from the World Wide Web: http://www.acsm.org/AM/Template.cfm?Section=Home_Page&Template=/CM/ContentDisplay.cfm&ContentID=7788
Nelson, M.E. et al. (2007). Physical activity and public health in older adults: Recommendation from the American College of Sports Medicine and the American Heart Association. Retrieved Nov. 29, 2007 from the World Wide Web: http://www.acsm.org/AM/Template.cfm?Section=Home_Page&Template=/CM/ContentDisplay.cfm&ContentID=7789
Pate, R.R., et al. (1995). Physical activity and public health: A recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. JAMA, 273(5), 402-407.
Lonnie Aquaro Sebastian is a cardiac rehab nurse and exercise instructor at Bryn Mawr Hospital, Bryn Mawr, PA, as well as a certified ACSM exercise specialist and ACE-certified group fitness instructor.