Importance of Determining Maximal Heart Rate for Providing a Standardized Training Stimulus

To the Editor We read with interest the Original Investigation in a recent issue of JAMA Internal Medicine by Zhang et al¹ who conducted a large, long-term randomized clinical trial to study the effects of moderate and vigorous exercise on nonalcoholic fatty liver disease (NAFLD). The authors conclude that moderate and vigorous exercise programs have similar effects on reduction of liver fat among patients with central obesity and NAFLD. Their data generally underline the significant role of exercise for mediating health benefits and improving the condition of NAFLD, which is becoming the most common liver disease worldwide. However, we are not really convinced of their conclusion and would like to provide a few comments.