Placing the Risks and Benefits of Physical Activity Into Perspective

Generally, habitual physical activity reduces risk of death due to heart disease, but in susceptible persons vigorous activity can increase the risk of sudden cardiac death and acute myocardial infarction. Susceptible adult individuals are primarily those with atherosclerotic disease.

The incidence of both acute myocardial infarction and sudden death is greatest in habitually sedentary individuals. Habitually sedentary men are 56 times more likely to experience cardiac death during or after vigorous exercise than while resting; however, very physically active men are only five times more likely to die during or after vigorous exercise than at rest.² Similarly acute myocardial infarction during or soon after vigorous physical exertion is 50 times more likely in least active than in most active subjects.³

Maintaining physical fitness through regular physical activity may help to reduce premature death because a disproportionate number of fatal cardiac events occur in the least physically active subjects performing unaccustomed physical activity. While sedentary people are advised to change their lifestyle and adopt regular physical exercise starting with low intensity and gradually increasing over time, they may need a preparticipation screening. Subjects with any health limitations need medical clearing and preferably a professional fitness coach. High-risk patients should be excluded from certain activities. For a brief set of guidelines, read “When to consult a health-care provider before engaging in physical activities.”

Even the most restrictive policies will never be able to completely prevent cardiovascular events associated with exercise. For individuals who exercise, it is important to recognize and report prodromal symptoms (symptoms preceding cardiac event). Prodromal symptoms were present in 50% of joggers, 75% of squash players, and 81% of distance runners who died during exercise. Prodromal symptoms may include chest pain/angina, increasing fatigue, indigestion/heartburn/gastrointestinal symptoms, excessive breathlessness, ear or neck pain, vague malaise, upper respiratory tract infection, dizziness/palpitations or severe headache. People who exercise have to be aware of this and physicians should inquire about exercise and these symptoms during exams.

For more details about risk/benefit and strategies to mitigate risks see the paper of Thompson PD et al.

References

1. Thompson PD et al. Scientific Statement From the American Heart Association Council on Nutrition, Physical Exercise and Acute Cardiovascular Events: Placing the Risks Into Perspective: Physical Activity, and Metabolism and the Council on Clinical Cardiology. Circulation. 2007;115:2358-2368; originally published online April 27, 2007; http://circ.ahajournals.org/content/115/17/2358

2. Siscovick DS, Weiss NS, Fletcher RH, Lasky T. The incidence of primary cardiac arrest during vigorous exercise. N Engl J Med. 1984;311: 874–877.

3.  Mittleman MA, Maclure M, Tofler GH, Sherwood JB, Goldberg RJ, Muller JE. Triggering of acute myocardial infarction by heavy physical exertion: protection against triggering by regular exertion: Determinants of Myocardial Infarction Onset Study Investigators. N Engl J Med. 1993;329:1677–1683.

Post written by: Petar Denoble, MD, D.Sc.

When to consult a health-care provider before engaging in physical activities

Physical activity (PA) is beneficial for health, but the transition from a sedentary lifestyle to PA or a change in the level of habitual PA may be associated with risks, especially in subjects with preexisting heart disease. The position paper of the European Association of Cardiovascular Prevention and Rehabilitation provides in-depth guidelines for preparticipation evaluation that is useful for recreational scuba divers, too. According to the classification of PA levels referred to in this article, scuba diving  falls under moderate-intensity PA, while some situations can emerge in diving that would correspond to high-intensity PA.

Classification of PA levels

1. Low intensity intended PA, corresponding to 1.8-2.9 METS
2. Moderate intensity intended PA, corresponding to 3-6 METS
3. High intensity intended PA, including individuals participating/willing to participate in masters events such as long-distance cycling, city marathons, long-distance cross-country skiing and triathlons, corresponding to greater than 6 METS.

For more details about METS, take a moment to review the Compendium of Physical Activities page.

For a quick orientation to assess your need for medical evaluation, use the Preparticipation Screening Questionnaire below. It is of utmost importance to be honest with yourself when it comes to conditions and symptoms asked in the questionnaire. Remember, you keep the keys to your safe participation in PA and in scuba diving.

American Heart Association/American College of Sport Medicine Health/Fitness Facility Preparticipation Screening Questionnaire:

Section I: History

You have had:

• A heart attack
• Heart surgery
• Cardiac catherization
• Coronary angioplasty (PCI)
• Pacemaker/implantable cardiac defibrillator/rhythm disturbance
• Heart valve disease
• Heart failure
• Heart transplantation
• Congenital heart disease

Symptoms:

• You experience chest discomfort with exertion
• You experience unreasonable breathlessness
• You experience dizziness, fainting, blackouts
• You take heart medications

Other health issues:

• You have musculoskeletal problems
• You have concerns about the safety of exercise
• You take prescription medication(s)
• You are pregnant

If you have marked any of the statements in Section I, consult your healthcare provider before engaging in exercise. You may need to use a facility with a medically qualified staff.

Section II: Cardiovascular risk factors

• You are a man older than 45 years
• You are a woman older than 55 years or you have had a hysterectomy or you are postmenopausal
• You smoke
• Your blood pressure is>140/90 or you do not know your blood pressure
• You take blood pressure medication
• Your cholesterol level is >240mg/dl or you do not know your cholesterol level
• You have a close relative who had a heart attack before the age of 55 (father or brother) or 65 years (mother or sister)
• You are diabetic or take medicine to control your blood sugar
• You are physically inactive (i.e. you get <30min of physical activity at least 3 days/week)
• You are >20 pounds overweight

If you have marked 2 or more of the statements in Section 2, consult your health-care provider before engaging in exercise. You might benefit from using a facility with a professionally qualified exercise staff to guide your exercise program.

If none of the above statements in Section 1 and 2 were true, you should be able to exercise safely without consulting your health-care provider in almost any facility that meets your exercise program needs

Adopted from Balady. Circulation 1998; 97:2283-2293. PCI, percutaneous coronary intervention.

 References

Borjesson M, Urhausen A, Kouidi E, et al. Cardiovascular evaluation of middle-aged/senior individuals engaged in leisure-time sport activities: position stand from the sections of exercise physiology and sports cardiology of the European Association of Cardiovascular Prevention and Rehabilitation. Eur J Cardiovasc Prev Rehabil 2010; June 19 (http://cpr.sagepub.com/content/early/2011/01/14/HJR.0b013e32833bo969.full.pdf)

Post written by: Petar Denoble, MD, D.Sc.

The Safety of Sports for Athletes With Implantable Cardioverter-Defibrillators

Current recommendations for patients with implantable cardioverter-defibrillators (ICDs) advise against participating in sport that are more vigorous than bowling or golf. These recommendations are based on reasonably estimated hazards of ICD failure to defibrillate, loss of control and injury caused by arrhythmia-related syncope or shock, and damage to the ICD system; however, the data about occurrence of these adverse events was not available. Medical conditions for which ICD is administered vary as well as the age of receivers. Many subjects with ICD are young and otherwise healthy. Participation in sports for some is an important quality of life factor and they choose to participate despite possible risks. The frequency of adverse events and risk of serious injury in such subjects was addressed in a prospective study based on a multinational registry.

Patient-centered care is a basic principle in which the patient establishes what brings quality to his/her life and challenges the physician to provide evidence so the patient can make an informed decision. In this case, that evidence is not established; this provided the ethical justification of a study that reviewed subjects who were enrolled in activities against medical advice. The study protocol had to ensure that it does not appear as an encouragement for subjects with ICD to engage in sports.

The study enrolled 372 athletes with ICDs (age: 10–60 years) already participating in organized (n=328) or high-risk (n=44) sports and followed them prospectively for a median of 30 months. Data was obtained via phone interviews and medical records at baseline, if a shock occurred and every 6 months. Of the enrolled subjects, 33% were women.  Sixty subjects were competitive athletes. Running, basketball, and soccer were the most common sports, but some also engaged in skiing (71) and surfing (13), which is considered high risk for syncope and ICD shock-related injuries.

This study found that shocks were not uncommon, but there were no injuries, deaths or need to externally defibrillate. Shocks occurred in 10% of study participants during competition/practice, in 8% during other physical activity and in 6% at rest. Lead malfunctions were not higher than in unselected populations.

In summary, many athletes with ICDs can engage in vigorous and competitive sports without physical injury or failure to terminate the arrhythmia, despite the occurrence of both inappropriate and appropriate shocks. This study also points out subgroups with likely higher risks; it also discusses specific tests and the process of patient evaluation necessary for informed physician advice and patient choices.

For my target audience, it is important to note that no scuba divers participated in this study. Scuba diving is considered a very high risk activity for subjects with ICD because the loss of control due to syncope or shock while underwater is likely to cause drowning. Some subjects with pacemaker, a device that does not provide shock, may be allowed to dive, but it appears that there are few out there since we had a lot difficulty recruiting participants for a survey-based study.

Lampert R, Olshansky B, Heidbuchel H, et al. Safety of Sports for Athletes With Implantable Cardioverter-Defibrillators. Results of a Prospective, Multinational Registry. Circulation. 2013;127:2021-2030.)

 More about DAN’s study on diving with pacemakers can be found here:

DAN Investigates Implanted Cardiac Devices: Volunteers Needed

Post written by: Petar Denoble, MD, D.Sc.

Effects of a single dive on small airway functions in divers with asthma

Diving with asthma is still a bit of a controversial issue due to insufficient research of how divers with asthma respond to dive conditions and lack of data on their dive safety. A recent study conducted by a group of researchers associated with DAN Europe contributes to current knowledge how diving may affect small airways function in divers with asthma. They conducted pulmonary function tests in 22 divers with asthma and 15 healthy control divers, before and after a single pool dive to 15 feet (5 meters).  A single pool scuba dive to a depth of 15 feet may impair small airways function in divers with asthma. Among the subjects, no one experienced any symptoms, but the effect on small airways varied significantly among divers with asthma. Most showed a minimal reduction of function (3 – 10%) not seen in healthy divers, while one diver exhibited a reduction of 22-26% in FVC, FEV1 and PEF of the predive values. The latter change was significant enough to advise the diver against further diving.

It is important to notice that all divers with asthma participating in this study were previously cleared for diving and have been diving for an average of four years. They did not report any incident of asthma attack or difficulty breathing while diving although they recorded between 10 and 220 dives in the past.

Asthma manifests in various forms; provocative factors, frequency and severity of symptoms and fitness to dive should be evaluated on an individual basis. Obviously, not all people with asthma would qualify for diving. The individuals included in this study are those that passed medical evaluation. It appears that they and their physicians made a reasonable decision. The only diver who had significant changes in small airway functions somehow bypassed physical evaluation by a physician prior to diving and made his choice without a physician’s opinion.

The article is a good read for any diver or would-be diver with asthma as well as for diving physicians. It gives an overview of available literature on the topic and provides extensive discussion of factors that should be considered in the fitness evaluation process.

Ivkovic D, Markovic M, Todorovic BS, Balestra C, Marroni A , Zarkovic M. Effect of a single pool dive on pulmonary function in asthmatic and non-asthmatic divers. Diving and Hyperbaric Medicine 2012; 42(2): 72-77 

Post written by: Petar Denoble, MD, D.Sc.