New Study Explores Why Maximum Heart Rate Decreases with Age
It is a known fact that a person’s maximum heart rate decreases with age. Such natural process does not only make ageing athletes less likely to retain their youthful performance but is also the leading cause of hospital admissions among otherwise-healthy elderly individuals. The question is – why does it happen? Researchers at the University of Colorado have recently explored the answer.
According to the new study which was published in the Proceedings of the National Academy of Sciences, heart rate decreases with age because ageing depresses the spontaneous electrical activity of the heart’s natural pacemaker – the sinoatrial node. In one experiment, the researchers observed that the maximum heart rate was slower in older mice than in younger mice, which is similar in humans. But what surprised them is that the individual pacemaker cells in older mice beat at a much slower phase than that of the younger animals. The same holds true even if they have been stimulated by fight-or-flight response which can be observed in individual cells.
According to the researchers, the slower beating rate was due to a limited set of changes in the action potential waveform, the electrical signal that is generated by the cells, which were caused by the altered behaviour of some ion channels – proteins that conduct electricity across the cell membrane.
Such discovery opens up many more questions and avenues for future research. Also, the study raises the possibility of developing new drug therapies that could slow the loss of aerobic capacity with age. For now, people can improve and maintain their aerobic capacity at all ages if they will exercise regularly, the researchers note.
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