What is the best time to exercise?
“Perhaps the morning versus evening choice is more critical for patients with underlying health conditions. “
A quick comment by someone from of the Linus Pauling Institute, 2024
     Reading your article about time of day for exercise caused me to recall articles from years ago about an increased risk of cardiovascular events from morning exercise. A search of Google Scholar turned up a few. I’ve included a few quotes (see below). However, I found most interesting a review article titled “Morning Vs Evening Exercises: Which Gives A Better Outcome?” by WMMS Bandara and AJIS Rathnayake, Medicine and Critical Care 3.9 (2019): 601-609. Their review article cites many studies under the headings “Morning is better” and “Evening is better.” Many impressive objective results are given for each. After those is a section with supporting citations for “No difference.”
     Perhaps further research can define which of the affected parameters are more important for particular groups (diabetic, CVD patients, active vs sedentary, young vs old, and genetic differences). The Science article you quoted about morning exercising being better for glucose control is tempered by the paper, “Afternoon exercise is more efficacious than morning exercise at improving blood glucose levels in individuals with type 2 diabetes: a randomised crossover trial” (Diabetologia, 2019 Feb;62(2):233-237).
Perhaps the morning versus evening choice is more critical for patients with underlying health conditions. Here’s some quotes that seem sobering for some people considering a switch to morning exercising:
“Many recent studies indicate that myocardial infarction, anginal attack, sudden cardiac
death, and stroke s occur more frequently in the early morning when the morning surge in BP develops.”
“We conclude that the magnitude of morning surge in blood pressure after arising from bed was
related with the severity of hypertensive target organ damage.”
–Cardiac Implications of the Morning Surge in Blood Pressure in Elderly Hypertensive Patients: Relation to Arising Time, Iwao Kuwajima et al. Am J Hypertens 1995;8:29-33
“Sudden cardiac and cerebral events are most common in the morning. A fundamental question is whether these events are triggered by the increase in physical activity after waking, and/or a result of circadian variation in the responses of circulatory function to exercise.”
“Since cerebral autoregulation is reduced in the morning, this surge in BP may also exacerbate the risk of hemorrhagic and ischemic strokes in the presence of other acute and chronic risk factors. Increased sympathetic activity, decreased endothelial function, and increased platelet aggregability could also be important in explaining the morning peak in cardiac and cerebral events but how these factors respond to exercise at different times of day is unclear.”
“Our results suggest that exercise shifts vagal influence and increases temporal dynamics of the heart rate to the 2nd quarter of the day and suggest that this may be the underlying physiological change leading to a decrease in adverse arrhythmic events during this otherwise high-risk period.”
–Temporal dynamics of the circadian heart rate following low and high volume exercise training in sedentary male subjects. 21 May 2015, Eur J. Appl. Physiology, H.F. Jelinek et al.
“The results suggest that diurnal variation of hemodynamic responses to increased oxygen demand may explain, at least partly, why myocardial ischemia of effort angina is more severe in the morning than in the afternoon.”
–Morning increase in hemodynamic response to exercise in patients with angina pectoris. D. Saito et al, Heart and Vessels, 8: 149-154 (1993).
P.S. – Off the record. — In regards to your goal of hitting 151, I thought I’d mention a couple things. First, you might find interesting the Wiki page for Jeanne Calment, especially the success of her reverse mortgage:  https://en.wikipedia.org/wiki/Jeanne_Calment