Exercise & the Heart- 10 Questions Answered

Exercise, Health, & the Heart

Ten Questions Answered

Including “Is sex good exercise?”

                      E.Roehm, M.D. 2012

Ten Questions Answered:

1. How much physical activity is needed to decrease the risk of a heart attack?
2. Does the risk of heart attack increase during physical activity?
3. What is the best physical activity for someone trying to improve health and decrease risk of cardiovascular disease?
4. Is sex good exercise?
5. Are exercise boot camps healthy endeavors?
6. What type of exercise is optimal for weight loss: swimming vs. walking?
7. How much exercise is needed to achieve an aerobic training effect?
8. Is it necessary to aim for a specific heart rate during exercise?
9. What is the effect of aerobic exercise on the brain and mental function?
10. What about exercise like Tai Chi, physical therapy for strengthening extremities, and exercises to strengthen core body muscles?


Physiology of aerobic exercise:

Regular aerobic exercise leads to many physiologic changes that, in general, are beneficial to health. Regular aerobic exercise leads to improved contraction and relaxation of the heart. The amount of blood that is ejected with each contraction of the heart increases and the resting heart rate decreases. The peripheral blood vessels in the body outside the heart are favorably affected and become better adapted at accepting the increased cardiac output that occurs during aerobic exercise. Favorable metabolic effects include increased insulin sensitivity, resulting in better blood glucose levels and an improvement in markers of immune function.

Ten Questions Answered:

1. How much physical activity is needed to decrease the risk of a heart attack?

The amount of physical activity needed to show a reduction in heart attack incidence is surprisingly small.1 Moderate physical activity for an average of approximately 20 minutes per day (150 minutes per week) is associated with a 14% reduction in heart attack rate. Doubling that amount of physical activity is associated with a 6% additional decrease in heart attack rate resulting in an overall 20% reduction in heart attack. A subsequent further increase in activity only modestly provides additional risk reduction. Hence, the majority of the benefit of exercise in decreasing cardiovascular risk occurs at relatively low levels of exercise.   return to questions

2. Does the risk of heart attack increase during physical activity?

Most studies show an increased risk during the short time vigorous physical activity is actually being performed. However, overall there is a net reduction in risk for those individuals who are physically active. This means that most people who exercise regularly are less likely to experience a heart attack even though they are at a slightly increased risk during the short time interval that the exercise is being performed. (Patients with certain health problems can be at risk during exercise and should discuss this with their physicians prior to embarking on an exercise program.)   return to questions

3. What is the best physical activity for an exercise program for someone trying to improve health and decrease risk of cardiovascular disease?

The goal is to engage in a sustainable and enjoyable form of activity that is both easy to pursue and can be continued for decades.
Walking, swimming, bicycling, and jogging are all superb forms of exercise. From the point of view of being sustainable and easy to pursue, walking is an optimal form of activity for the human body. Swimming can be utilized by a number of individuals with orthopedic problems that limit walking.
Those fortunate individuals that are blessed with wonderful joints can continue jogging into their 80s, though this is not true for the majority of the population.
The optimal physical activity for an individual derives from a combination of personal preference, orthopedic capabilities, and age.     return to questions

4. Is having sex good exercise?

The aerobic activity of sex for a couple that are long term partners is about the equivalent of walking up 2 flights of stairs at a moderate rate, which correlates to approximately 5 METs (metabolic equivalent) of exercise. Sexual activity with a new or less familiar partner generally results in increased energy expenditure2,3.

Substantially higher workloads in the amount of exercise with sexual activity can also occur due to differences in vigor as a result of age and individual circumstances.

There may be health benefits of regular sexual activity. A 40% reduction of heart attack frequency has been associated with having sex at least twice a week compared to sex less than once a month in a group of men followed for 20 years.4

Since one of the keys of a good exercise is being an enjoyable physical activity that can be sustained on a regular basis for years; the answer is yes- sex is good exercise. return to questions

5. Are exercise boot camps healthy endeavors?

This depends on the individual participant and the particular boot camp. For middle aged and older individuals, my opinion as a cardiologist is that a stress test is advisable before going from a sedentary lifestyle going to a vigorous physical conditioning program.

The goal for an exercise program is to start a long standing life style change which includes regular exercise. Different individuals are more subject to various orthopedic injuries with various types of exercise. An overly vigorous program resulting in a knee injury or persistent back strain is no favor to the participant.
Pain is not necessarily gain. A sustainable exercise program that is adjusted for the capabilities and orthopedic status of its participants is ideal.  return to questions

6. What type of exercise is optimal for achieving and maintaining weight loss?

Many individuals who have lost substantial amount of weight did so while walking 60 minutes daily at a moderate pace. (That doesn’t mean that other types of exercise can not be employed or that exercise of a shorter duration is not helpful.) Exercise that can be sustained for the long term is an important factor.

The National Weight Control Registry is a descriptive study of a large number of individuals who have achieved and sustained a major weight loss, with the average weight loss being 66 lbs and maintained for over 5 years.5 Approximately 94% of these successful individuals increased their physical activity to lose weight. The most frequent physical activity utilized was walking. The average duration of the physical activity during efforts to maintain the weight loss was one hour per day.

My personal observation is that daily jogging of at least 1 ½ miles per day is also associated with significant sustained weight loss in many individuals.

   What about swimming vs. walking, jogging, or bicycling?
The standard answer to this for many years was that swimming seemed to be less effective for achieving weight loss than other activities, dating back to research from 1987.6 However, two relatively recent studies have shown equivalent weight loss for swimming compared to an equivalent amount of walking.7,8 Hence, it appears that swimming may be a very reasonable approach for helping with weight loss.   return to questions

7. How much exercise is needed to achieve an aerobic training effect?

Any amount of aerobic exercise has some beneficial training effect compared to not exercising and simply sitting in a chair or lying in bed. Walking 10 minutes per day, irrespective of the heart rate achieved, leads to a training effect substantially better than no activity.
In regards to how much exercise is required to achieve an increase in aerobic capacity (capacity of the body to utilize oxygen for work), this has been studied and quantified by Ken Cooper, M.D., who did much to popularize aerobic activity. Dr. Cooper studied military personnel performing different types of physical activities at various speed and the relative aerobic expenditure for each activity was quantified. A number of the early Ken Cooper Aerobic books published in the 1960s and 1970s have an appendix listing various physical activities quantified in relation to the aerobic conditioning effect.9
Jogging 2 miles in 15 minutes for example, is substantially more aerobic conditioning than walking those same 2 miles in 35 minutes, even though the jogging is completed in a significantly shorter time.   return to questions

8. Is it necessary to aim for a specific heart rate with exercise?

No, it is not generally necessary. Many individuals, however, find that keeping track of their heart rate is useful for gauging the intensity of the physical activity. And, some cardiac patients must keep track of their heart rate in order to prevent developing a heart rate above that which has been determined by prior exercise stress testing to be the highest prudent heart rate which is acceptable for them.

A useful piece of information is that when a healthy individual’s respiratory rate begins to rise with exercise, that the cardiac output typically has already increased significantly above resting levels and a good conditioning effect is occurring.

Another traditional guidepost for exercise is to perform exercise at a level which is approximately 70-80% of one’s predicted heart rate. Maximum heart rate can be estimated by the simple calculation: 220-age. For example, in a 50 year old individual, the following calculation estimates 70% of maximum predicted heart rate: (220-50) x 0.70= 119 beats/min. There are many variations of this formula, including modifications which are particularly useful for individuals with a high resting heart rate. For patients taking the type of medications called beta blockers, these types of calculations are not reliable and overestimate the achievable heart rates that a patient will obtain.

What about walking 30 minutes daily without checking one’s pulse? For an individual without any special health considerations, this activity is associated with a substantial reduction in risk of heart attack and is a very beneficial. return to questions

9. What is the effect of aerobic exercise on the brain and mental function?

The research advances in this area in the past 10 years have been very exciting. In 2006, a University of Illinois randomized trial10 showed that one hour of walking three times a week at a moderately brisk pace (slightly over 3mph) compared to performing stretching exercises, resulted in both improvement in mental function as well as actual physical changes in the brain of the exercise participants as assessed by MRI (magnetic resonance imaging). The participants in the study were between 60-79 years of age.

The brain volume in the exercise group actually increased in regards to the grey matter in the frontal area of the brain which is associated with higher order thinking. The volume of the white matter of the brain also increased, including the structure that interconnects the right and left hemispheres of the brain, the corpus callosum. The physical changes found in the human brain parallel the positive effects of exercise that has been seen in experimental studies in animals.  return to questions

10. What about exercise like Tai Chi, physical therapy for strengthening extremities, and exercises to strengthen core body muscles?

Particularly the elderly benefit from these types of exercise. Tai Chi has additional potential benefits regardless of age because of its stress reduction component.

Any exercise which strengthens core body muscles as well as extremities will decrease falls and increase mobility in the elderly. Falls often lead to a further substantial decrease in physical activity, as well as bone fractures. Activity enhances health and inactivity leads to an acceleration of physical decline and disability. Hence, these activities are particularly valuable for the health of the elderly.

Final take away point:
The key to obtaining benefit from exercise is to find an activity that will be regularly performed for years. The bottom line is to find an exercise that is enjoyable and that your body can perform for the long term.    return to questions

by Eric Roehm, MD                       2012
Fellow of American College of Cardiology

References

1. Sattelmair J, Pertman J, Ding EL, et al. Dose response between physical activity and risk of coronary heart disease: a meta-analysis. Circulation. 2011;124:789-95.

2. Falk RH The Cardiovascular Response to sexual activity. Do we know enough?
Clinical Cardiology. 2001; 24: 271-5.

3. Hellerstein HK, Friedman EH Sexual activity and the post coronary patient. Arch Intern Med. 1970;125:987-999.

4. Ebrahim S, May M, Shlomo Y, et al. Sexual intercourse and risk of ischaemic stroke and coronary heart disease: the Caerphilly study. J Epidemiol Community Health. 2002;56:99-102.

5. www.nwcr.ws/Research/default.htm   (accessed 2012)

6. Gwinup G. Weight loss without dietary restriction: efficacy of different forms of aerobic exercise. Am J Sports Med. 1987;15:275-9.

7. Gappmaier E, Lake W, Nelson AG, et al. Aerobic exercise in water versus walking on land: effects on indices of fat reduction and weight loss of obese women. J Sports Med Phys Fitness. 2006;46:564-9.

8. Cox KL, Burke V, Beilin LJ, et al. A comparison of the effects of swimming and walking on body weight, fat distribution, lipids, glucose, and insulin in older women–the Sedentary Women Exercise Adherence Trial 2. Metabolism. 2010;59:1562-73.

9. Ken Cooper, MD, MPH. Aerobics. Bantam Books 1968.

10. Colcombe S, Erickson K, Scalf P, Kim J, Prakash R, McAuley E, Elavsky S, Marquez D Hu w L, Kramer A. Aerobic Exercise Training Increases Brain Volume in Aging Humans. The Journals of Gerontology: Medical Sciences 2006;6:1166-70