For the past 30 years running shoes have been designed with thickly cushioned, built-up heels. This type of shoe forces the body to balance itself in an unnatural, backward-leaning position. Your toes are pointing downward, your weight is shifted rearward, and your back is arched back slightly. Basically, you’re body is trying to maintain balance while compensating for the lifted heel.

 If you’ve been running this way for years — and most people have — it’s likely the muscles and other soft tissue in your feet, lower legs and core will need to adapt before completely transitioning to a more natural gait in flat shoes. In particular, you will need to give your Achilles tendons and calf muscles time to adjust to level shoes.

The Achilles tendon acts like a large rubber band that stretches and recoils with every stride. If you’ve been wearing shoes with an elevated heel — including your everyday work and casual shoes — your Achilles tendon along with the calf muscle group is conditioned to a shorter range of motion. When you begin running in a level shoe like a Newton Running shoe, the Achilles tendon and calf muscles needs to stretch to accommodate for the 10-15mm distance that used to be taken up by an elevated heel.

If you abruptly transition from an elevated heel to doing all your mileage in a level shoe, you’re likely to feel some Achilles and calf muscle soreness. Instead, make the transition gradually: run less than a mile at a time just a couple of days per week. Work on your form and build strength in your feet, ankles and lower legs with the following tips:

Make the switch to natural running shoes

Work on strength and balance:

• Go flat as often as possible! Ease the transition on your Achilles and calf muscles by walking barefoot as much as possible. Wear flatter shoes even when you’re not running.
• Do balancing drills. Stand on one foot with a mostly straight leg, lift the other foot off the ground at a 90 degree angle and close your eyes. If you can maintain balance for 30 seconds with your eyes closed on both sides, you may have enough strength be begin transitioning to level shoes. If you lose balance on either side, make this drill part of your daily regime. (Be sure to work on each foot.)
• Do barefoot heel dips on a staircase. While holding on to a wall or railing, balance yourself with your metatarsal heads on the edge of the stair even with the ball of your foot. Slowly dip your heel below the plane of the stair, feeling the stretch in your Achilles and calf muscles and then slowly raise back up.

Increase the flexibility and range of motion in your feet and lower legs:

• Do common wall stretches. Lean into a wall with your hands while flexing the lower calf with a flat foot. Do this with both a straight and bent knee and repeat a couple times per day after the muscles are sufficiently warm.
• Increase the flexibility of your plantar fascia. While sitting in a chair, cross your leg over your knee and firmly push your fingers or a thumb into the center of the sole of your foot. Maintain that pressure and point your toes up and down to stretch the plantar fascia.
• Focus on running form. Most runners have been overstriding and landing with a heel strike. A common mistake for people who are adjusting is over-striding and landing on the forefoot or toes in front of your body. This still causes too much braking and impact on the feet and lower legs. Try the following instead: march in place and notice how your foot lands relaxed under your body. You are lifting your foot and leg off the ground with your core muscles. Now simply fall forward,  lifting quickly. Shorten and quicken your steps, balancing on one leg at a time as you move forward.
• Be relentless with running form drills. Accentuate specific aspects of good form drills and train your body to repeat specific movements while you are running. Skipping, bounding, high knees and butt kicks are easy form drills that and don’t take a lot of time. Don’t ignore these once your workout is complete.
• Watch yourself run. Having a friend video your stride in your traditional shoes, your level shoes and while running barefoot on grass. Notice how your body moves differently in each scenario. Pay close attention to what you do while running barefoot. Are your feet landing under your mass? Are you running with a quick cadence and relatively short strides? Are you running with upright but slightly forward-leaning posture? Are you carrying your arms close to your body at about a 90-degree angle? Adopt this form in your new shoes.

Written by Danny Abshire: Danny Abshire is the author of “Natural Running” and the co-founder of Newton Running, a Boulder, Colo.-based company that makes shoes that promote an efficient midfoot/forefoot running gait. He has been making advanced footwear solutions for runners and triathletes for more than 20 years. For more, go to newtonrunning.com.