pre- and post-MI are lacking, there have been several published animal
studies. Studies using rat models have shown a definite benefit to
swimming before an MI. In rats, a pre-MI swimming regimen, which
consisted of a 7-week program,was subsequently shown to significantly
reduce scar size after the MI. In addition, swimming pre-MI was
shown to increase the rate of expression of key beneficial genes
involved in LV remodeling [75]. Gaudren et al. evaluated swimming as
an endurance exercise after anMI in rats. Data did not showa mortality
or remodeling benefit or harm after a small infarction. However, swimming
was actually shown to cause harm in rats that had a large infarction
area. The harm was caused whether the swimming was initiated
early or late after an MI, but more profound in exercise regimens initiated
early after anMI.Deathwas a result of aggravated LV remodeling and
wall stress caused by endurance exercises, and was postulated as a
caveat to starting any type of endurance exercising after an MI causing
LV dysfunction [76]. Extrapolation of results is difficult because of differences
in species, and due to difficulty in standardizing the extent of
infarct and intensity of exercise. However, results indicate that swimming
rehabilitation programs should not be initiated immediately
after an MI, and that further research is needed on the optimal time
after an MI to start a program.
Needless to say, the results of swimming in patients with CAD
have had varied results. The difference may lie in the stability of the
CAD, as prior investigations have shown that sudden death that
occurs in men with severe CAD is a result of plaque rupture [77].
However, it appears that swimming can be tolerated well in patients
with stable disease, and should be used following physician screening
in those patients in cardiac rehabilitation. Specifically, heart rate
monitoring with specific exercise prescriptions may be needed in
such patients to ensure safety during water exercises.