He genuinely rolls into my office every three months, shoes still attached to his carbon-fiber lifestyle. Lycra moist, Apple Watch vibrating, resting heart rate of 42. He is fit, intelligent, and tightly wound.
“Doc,” he starts, eyes wide, “I came across that morning workouts burn more fat and reduce clotting factors. Should I shift my rides to earlier? Or perhaps a late evening session is better for heart rate variability?”
This is a man who, when he’s not cycling, is deep in an internet rabbit hole about the next minimal gain. He already exercises more in a week than most of my patients do in a year. Yet here he is, worried that his 6 p.m. spin class might be decreasing his lifespan.
Here is the truth I share with him, and now with you: It does not matter.
The science (such as it is)
Yes, there are studies. The UK Biobank analysis of 90,000 individuals found morning exercisers had slightly lower rates of coronary events. Another trial indicated evening workouts enhanced lipid metabolism and resting heart rate overnight. Afternoon training may coincide with circadian peaks in lung function and muscle strength.
The issue? These effects are minor, inconsistent, and probably irrelevant to the average person who can hardly fit in a thirty-minute walk three times weekly. They are statistically significant in a way that creates careers in exercise physiology, not in a manner that saves your patients’ lives.
The heart does not possess a clock.
Your myocardium is unaware if the sun is rising or setting. It recognizes shear stress, stroke volume, and whether the endothelium is being stressed. It understands if you are moving most days, over the years.
Medicine has a poor tendency to fetishize precision while overlooking the apparent. We debate LDL subfractions while our patients continue smoking. We argue kale versus quinoa while they consume soda. And now, we are allowing them to believe there is a “perfect” time to sweat.
The real prescription
The ideal time to exercise is when you won’t cancel. Early riser? Jog at dawn. Night owl? Hit the gym after dinner. Parent of toddlers? Congratulations. Your window is whenever Paw Patrol gives you twenty-seven minutes of calm.
Consistency outweighs clock time. Habits surpass hacks.
Why this matters for doctors
Every time we indulge the “optimal timing” discussion, we feed the anxious, over-quantified patients who believe health is unlocked by manipulating circadian biology. Meanwhile, the rest of our group is inactive and waiting for a stent.
Our role is not to create new anxieties. It is to simplify. To remind individuals that movement is medicine, and that the dosage, not the timestamp, is what matters.
My irreverent takeaway
So here is what I tell my patient:
“Ride when you feel like it. You are already doing the challenging part. If you want a true marginal gain, stop stressing about when to exercise and start focusing on whether you will continue exercising when you are 70.”
If he takes that advice, he will live longer. And I will spend less time debunking PubMed articles masquerading as wellness hacks.
Bottom line: The best time to exercise for heart health is the time you will actually do it again tomorrow. Everything else is noise.
Larry Kaskel is an internist and “lipidologist in recovery” with over thirty-five years of medical practice. He runs a concierge practice in the Chicago area and is on the teaching faculty at the Northwestern University Feinberg School of Medicine. He is also affiliated with Northwestern Lake Forest Hospital.
Before podcasts became mainstream, Dr. Kaskel hosted Lipid Luminations on ReachMD, producing a library of more than four hundred programs featuring prominent figures in cardiology, lipidology, and preventive medicine.
He authored Dr. Kaskel’s Living in Wellness, Volume One: Let Food Be Thy Medicine, a work that combines evidence-based medical practice with practical strategies for enhancing healthspan. His current projects include reassessing the cholesterol hypothesis and exploring the infectious origins of atherosclerosis. More information is available at larrykaskel.com.