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Dr Paul Bhella (John Peter Smith Hospital, Fort Worth, TX) explained that heart muscle size—typically measured by left ventricular (LV) mass—peaks early in life and diminishes with sedentary aging.
He conducted a study to look at the effect of regular exercise on this process and found that being physically active over the course of a lifetime can “preserve the heart”s youthful elasticity.”
He noted that as the heart muscle atrophies with age, the heart becomes weaker, less capable of responding to increasing demands such as those associated with physical activity, and, in many circumstances, this leads to a stiffening of the heart by increasing the relative proportion of connective tissue compared with cardiac muscle.
During the study, Bhella and his colleagues compared two groups of people: 81 healthy but sedentary individuals aged 21 to 82 years; and 67 people aged 65 or older who had exercised regularly throughout their lives. The second group was subdivided into those who had exercised two to three times per week, four to five times week, and six to seven times per week. Exercise was defined as a period of at least 20 to 25 minutes of aerobic activity. Study participants underwent cardiac MRI to estimate cardiac mass and LV mass.
Results showed that in the sedentary group, LV mass reduced with age from an average of 55 g/m2 in those in their 30s to 24 g/m2 to those in their 60s. In contrast, in those older individuals who had done regular exercise, LV mass either stayed stable or actually increased, and there was a clear dose-dependent effect with the amount of exercise taken. Those who had did exercise two to three times were per week, had an average LV mass of around 53 g/m2, and this increased to about 62 g/m2 in those exercising four to times a week and to about 68 g/m2 in the six-to-seven-times/week group.
Similar results were seen with peak oxygen uptake. This decreased steadily with age in the sedentary group but increased with increasing exercise levels in the active group. Those individuals aged over 65 who exercised four to five times a week had a higher level of peak oxygen uptake than those aged under 34 who were sedentary.
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