- History of athletic training and performance.
- Enhanced exercise ability (V̇o2max > 40 mL/kg/min).
- Resting bradycardia.
- Increased left ventricular mass by echocardiography.
The concept of the athlete’s heart is one that has been postulated for almost 100 years, promulgating the idea that myocardial
hypertrophy could be a purely physiologic phenomenon. Media attention
to the sudden deaths of widely known athletes has helped focus attention
on the important distinction between pathologic cardiac hypertrophy
and physiologic hypertrophy and the upper limits of the latter.
The adaptations of the human body to physical training involve (but are not confined to) the cardiovascular system. The exercise-related
changes in other organ systems influence the cardiovascular response
to exercise. It is important for the physician to be familiar with
the physiologic responses to physical training in order to distinguish
them from similar changes that can occur with cardiovascular disease.
Different forms of exercise produce a number of physiologic responses. Also, cardiovascular responses to short-term training and prolonged
training differ. Exercise generally takes two basic physiologic
forms—dynamic and static, or isometric, exercise—although
most athletic activities are a variable combination of both forms
of exercise. Dynamic exercise constitutes an alteration in the length
of skeletal muscle with comparatively little change in muscle tension. Static
exercise is essentially the reverse—that is, a marked alteration
in skeletal muscle tension with little or no change in muscle length.
Distance running is a classic example of dynamic exercise; weight
lifting is a classic example of static exercise.
The morphologic and physiologic consequences of dynamic and isometric exercise are significant and may simulate changes associated with
cardiac disease. The normal limits of changes that are due to athletic
conditioning require careful identification. Awareness of these
limits improves the physician’s ability to determine the
end points at which normal anatomy and physiology become clinical disease.
Maron BJ et al. The heart of trained athletes:
cardiac remodeling and the risks of sports, including sudden death. Circulation. 2006 Oct 10;114(15):1633–44.
The acute cardiovascular responses to exercise are specific and vary with different forms of exercise (Figure
34–1). There are also specific adaptive responses to exercise, particularly to dynamic exercise. In particular, the adaptive change in heart rate from an alteration in vagal parasympathetic
tone defines the normal physiologic range; as noted earlier, this may be initially misinterpreted as representative of cardiovascular disease.
Cardiovascular response to exercise. A: Response to dynamic exercise progressively increasing workload to maximal oxygen consumption. B: Response to static handgrip contraction at 30% maximal voluntary contraction. ABP, systolic, mean and diastolic arterial blood pressures; HR, heart rate; Q, cardiac output; SV, stroke volume; TPR, total peripheral resistance; V̇o2, oxygen consumption.
(Reprinted with permission from Mitchell JH, Raven PB. Cardiovascular adaption to physical activity. In: Bouchard ...
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