For you couch potatoes out there with New Year’s resolutions to get out and exercise, you probably want to know how much – or if you’re like me, how little – you can get away with.
Exercise benefits are a tricky thing to measure. How do you quantify fitness? Let’s say you’re interested in how much exercise it takes to go from sedentary to fit. What exactly is sedentary? How do you objectively measure improvement or decline? What quantities do you use to define athletic? Is there a point at which physical activity becomes too much, in which there is a diminishing return or even a risk of death? What about mood changes? Can you measure a better mood? Define exercise. Is gardening exercise? Weight-lifting? Cleaning my basement?
Pick five large exercise studies at random, read them, and find some crudités perhaps, while you try to make sense of conflicting evidence. Methodology, measurements, definitions all vary from researcher to researcher. A little exercise lowers your risk of some things. Or does it? Risk of death decreases until you reach a certain threshold of activity, and then doesn’t change much. Recent research suggests marathon running might not be good for your heart. Huh? Exercise can kill you?
Exercise physiologists do use a variety of measurable data points: blood pressure, heart rate, recovery time after exercise, cholesterol, glucose, and oxygen utilization efficiency to name but a few. There are some validated questionnaires to assess mood around, but clearly there is a strong subjective component to anything asking you how you feel. With all of this swirling in my mind – along with dreams of donuts – I read a nifty post in the New York Times Health section this weekend, entitled:
The author, Gretchen Reynolds, does a great job of sifting through the evidence and consensus opinions. She makes sense of the latest thinking about METs and what they should mean to you, your body and your mind. Worth a read, then a walk, then a big helping of whole grains and broccoli.
Happy New Year, Buckeyes. Now get out there and give me 500 METs!
Victoria Rentel MD