But because that’s often easier said than done, you have to warm up, says Rachel Straub, a certified strength and conditioning specialist and co-author of Weight Training Without Injury. Obviously, the best things to do would be a) practice good posture and b) stay active throughout the day. Join Runner's World+ for unlimited access to the best training tips for runners

Play icon The triangle icon that indicates to play So if you run after prolonged sitting, then those big stabilizing muscles simply won’t work.” For example, tight hip flexors can cause an anterior tilt, which shuts down your abdominals and your glutes. “When these muscles tighten up, it creates musculoskeletal imbalances. “Sitting all day will make the front of your body tighten up-especially your hip flexors, rectus femoris (a quad muscle), pectoralis (chest), upper traps (upper back), and anterior scalenes (the front of your neck),” explains David Reavy, a Chicago-based orthopedic physical therapist at React Physical Therapy. All that sitting results in tight leg muscles and other issues.

And it definitely inhibits your exercise performance-you can’t, for example, sit for eight hours at work and then get up and run five miles without it affecting your body. Research indicates that no matter how much you exercise, sitting for excessively long periods of time is a risk factor for early death.

The notion that sitting isn’t good for you isn’t new, but if you think regularly running cancels out the negative side effects of sitting all day, well, you’d be wrong.

Does sitting down make your butt flat