The key to preventing back pain lies in strengthening the 'core' muscles that support the spine... rather than working on a six pack, according to new research.
A study of runners found those weak in this area were more prone to developing a condition that blights the lives of eight in ten Britons at some point.
Located around the stomach, back, pelvic floor and hips they control balance, posture and trunk stability - and are the foundation for movement.
And having a great six pack won't help. Despite this muscle, the Rectus Abdominis, forming part of the core, it is superficial.
The smaller, deeper muscles are those that protect against back pain. And unfortunately, most people's aren't nearly as strong as they should be, say scientists.
Experts say it is common for even well conditioned athletes to neglect their deep core, and there is a lot of misinformation online and in fitness magazines about core strength.
Traditional ab exercises with a large range of motion, such as sit ups or back extensions, will not give you the strong core needed to be a better runner.
Instead exercises that focus on stabilising the core, especially on unstable surfaces, are what's really going to make you a better runner.
He said these include the plank, said by pilates experts to be the best exercise for boosting core strength.
It involves lying face down on the floor with the arms locked in an L-shape, legs straight and bottom firmly in line with the rest of the body and not sticking up into the air.
Study leader Ajit Chaudhari, professor of physical therapy and biomedical engineering at The Ohio State University, said: "Working on a six-pack and trying to become a better runner is definitely not the same thing.
"If you look at great runners, they don't typically have a six-pack but their muscles are very fit.
"Static exercises that force you to fire your core and hold your body in place are what's really going to make you a better runner."
If the core muscles are weak other muscles have to compensate, which is where poor posture and back pain come in.
While running provides excellent aerobic conditioning, it can lead to chronic back pain or aggravate existing problems.
The new findings uncovers how to prevent back pain in runners and could have implications for other sufferers.
Prof Chaudhari said working on the deep core, not the abs, is essential to becoming a better runner.
The study published in the Journal of Biomechanics used motion detection technology and force-measuring floor plates to estimate muscle movements during activity.
Explained Prof Chaudhari: "We measured the dimensions of runners' bodies and how they moved to create a computer model that's specific to that person. That allows us to examine how every bone moves and how much pressure is put on each joint.
"We can then use that simulation to virtually 'turn off' certain muscles and observe how the rest of the body compensates."
His team found a weak deep core force more superficial muscles like the abs to work harder and reach fatigue faster.
When those superficial muscles are doing the work the deep core should be doing, there are often painful consequences.
Prof Chaudhari said: "When your deep core is weak, your body is able to compensate in a way that allows you to essentially run the same way. But that increases the load on your spine in a way that may lead to low back pain."
The core comprises all the deep muscles that connect the upper and lower body, including stomach, back, hips and buttocks.
Benefits include a flatter stomach and a better posture, as well as strength around the spine.
Nearly 10 million working days are lost each year for adults aged 25-64 due to back pain.
The financial cost to the UK economy is estimated to be around £12bn per year. There are also huge personal and emotional costs.