I gained around 15 pounds since the last time i was actually active regularly, so i decided to do a 5k training program I found. I used to play recreational team sports before Covid, have been sedentary for a while, so I decided to download an app and do their 5k training plan.
The problem is that the plan is for people who can already run, but want to tune themselves for doing a 5k quickly. My body is not used to running, and now i probably need to take a week or more break. Parts of my knee/leg which have never been sore before in my life are now sore.
My advice for myself if I could go back in time 3 weeks: Just because you were active before at some point in your life, doesn't mean your body can do the same stuff still. DON'T INCREASE YOUR MILEAGE BY MORE THAN 10% A WEEK, AND WARM UP AND STRETCH PROPERLY.
Also, doing some of your runs a low intensity really helps prevent injuries and improves your aerobic fitness.
The Maffetone rule, while being not very accurate is a good starting rule if you don't know your max heart rate. Try to stay below 180 - (your age) heart rate. Add 5 or 10 if you are an experienced runner, subtract 5-10 if you are very inexperienced or recovering from illness.