Claire Lo, Harvard College ’16
Can too much exercise be harmful for the heart? Although regular exercise has been associated with lower risk of chronic inflammatory disorders like coronary artery disease and type II diabetes mellitus, a growing body of literature suggests that a concomitantly high intensity, high volume training regime may introduce consequences that outweigh the benefits of moderate exertion. This review takes an explicitly evolutionary perspective to understanding the clinical implications of physical activity for cardiovascular health. Physical exercise induces a transient increase in serum high sensitivity C-reactive protein (hs-CRP), a well-established marker of systemic inflammation, by activating the acute-phase response. Although it is yet unknown whether the degree of inflammation, as measured by Δhs-CRP, varies directly as a function of exercise intensity, we hypothesize that higher levels of intensity evoke larger magnitudes of inflammation with slower decay kinetics. While the upper boundaries of beneficial exercise on heart health remain unclear, too little exercise is undoubtedly detrimental and fuels the astonishing prevalence of cardiovascular disease in post-industrial societies. Although physical activity is primarily a form of modern recreation, its roots in the origins of the human genus strongly suggest that it is a necessary stimulus for maintaining a healthy human body.