Just started running again after about 20 years in July, due to it being the only real exercise available while i quarantine as part of my work abroad. Jeez, it has been a hard road back, as the old leg muscles fairly ache when they are not used to doing something. Never ran at all during August as i am a cyclist by trade so concentrated on getting quality work done there before travelling again, but started up again on Saturday. Hip flexors played up on my 1st light run, but a lot of hip flexor stretching that night and the previous day sorted that out thankfully. Yesterday, did some glute activation exercises before hand so i wouldn't fall into the same trap the previous day and stuck to intervals, 40s walk/20s Sprint. Worked out great, first time since starting back that there was no pain and was getting a great mid/fore foot strike, it felt effortless doing the efforts and the glute work did the trick as i have some nice light doms going on in my butt today. I did this over a 4km distance. also invested in proper running trainers and finally settled on Adidas Boston 9's which seem pretty good so far and nice and light.