New Study says two days in a row of exercise can suppress the immune system.
No kidding. I knew this when I was in high school and used to play basketball all winter for 5 or more hours a day. I kept getting colds and when I finally went to a doctor and told him that I played basketball every day for hours and thought it might have something to do with it he said something simple. "Well, stop playing every day and take some time off for recovery." and I did and solved the problem.
That is easier said than done since exercise can become addictive and is a regimen that many form into a habit.
My routine is to vary the type, intensity, and duration of workouts. For instance.
Weight training: I do minor stretch bands and dumbbells more or less every day but don't stress if I miss a day. I go for more weight in curls and presses on an alternate day or every third day program and do this in the evening where it allows some repair and recovery, plus it manages metabolism for better sleep as blood sugar appears suppressed.
Calisthenics: Pushups, planks, crunches, etc. Every couple of days I find it worth doing this but not every day for me. Avoid the Gym and do calisthenics. - Interesting article.
Stretches: Every day simply for injury prevention, Hamstrings are my primary focus since this helps protect the back.
Cardio: This includes walking and tennis. You can moderate each so that doing them every day can be done without risk to most healthy people. If walking is overdoing it then as humans we've devolved into couch potatoes. It find a light tennis workout against a backboard or just taking serves is something I can do every day without concern. I think my body has acclimated to this as a standard condition whereas a higher workout might cause problems. That falls into the intense cardio category.
Intense Cardio: This can be tennis, jogging, sprinting, or just doing anything that brings the heart to a fast clip relative to your age and health. This is the area where risk seems the highest so learning to calibrate and discipline your workouts tailored to your needs is important.
Final Thought: Do what works for you and observe the results on how you feel. Your body will often let you know. When older it seems that the joints are the place where the most recovery is needed.
Disclaimer: Talk to your doctor, physical therapist, and physical trainer before embarking on a new program. This article is for information purposes only.