Hi - this is my first post on this site. I am 47 years old and weigh around 100 kg. I have completed the c25k - finishing w9 with a 5k parkrun and have ran 4.98 k on Monday and Wednesday this week. The day's after each run my lower back has ached. As I have done no exercise for the past 12 years I am suspecting that my core muscles still need strengthening. I do circuit training each Friday evening (for the past 6 weeks) but can you recommend any other way of strengthening core muscles?
I have new fitted trainers to run in so it is not them and I run in an upright position. Any suggestions gratefully received.