Running in old or worn-out shoes is one of the most common causes of running injuries. Your running shoes lose shock absorption, cushioning and stability over time. Continuing to run in worn-out running shoes increases the stress and impact on your legs and joints, which can lead to overuse injuries. The easiest thing you can do to prevent those types of injuries is replace your running shoes when they're worn-out.

So how do you know when shoes need to be retired? Don't use the treads of your running shoes to determine whether you should replace your shoes. The midsole, which provides the cushioning and stability, usually breaks down before the bottom shows major signs of wear. If you've been feeling muscle fatigue, shin splints, or some pain in your joints -- especially your knees -- you may be wearing running shoes that no longer have adequate cushioning.

A good rule of thumb is to replace your running shoes every 400-500 miles or so, depending on your running style, body weight, and the surface on which you run. Smaller runners can get new running shoes at the upper end of the recommendation, while heavier runners should consider replacement shoes closer to the 400 mile mark. If you run on rough roads, you'll need to replace your running shoes sooner than if you primarily run on a treadmill.

About halfway through the life of your running shoes, you might want to buy another pair of running shoes to rotate into your runs. Your shoes will last longer when you allow them to decompress and dry out between workouts. Also, having a fresh pair of shoes as a reference will help you notice when your old ones are ready to be replaced..

Biomechanics of Running

To help you understand basic human biomechanics & the different running styles, Intersport Cheltenham categorise footwear by suitability to each foot/running type.

Some scienctist's now suggest that mankind's ancesters have been walking upright for as long as 5,000,000years. Beginning by moving on two two legs through the trees, using arms for balance as much as an orangutan does today, we are designed to move in this way and our bodies have developed through evolotion to provide the very complex systems that allows us to walk up efficiently.

Our bodies are very adaptable, if you specifically overload its structures and physiology it will grow and adapt to that overloading, just as executing a bicep curl at the gym will grow your bisceps, our ancestry as hunter/gatherers meant that we spent our distant past on the move, our days were occupied running around trying to catch something to eat or running around trying to avoid being caught and eaten by something else. We ran for necessity.

Lifestlyes today are somewhat different, we lead a largely sedentary way of life and our running is usually confined to a leisure activity, we run for recreation, because more and more of our immediate landscape is covered in concrete and asphalt and our bodies are less well adapted to regular running, Intersport Cheltenham stock a range of sport shoes, designed to compliment the machanical assets nature has supplied. To understand the biomechanics of running and the techonlogies we employ, its is necessary to first of all understand some our physical mechanisms.

TheGait Cycle

The gait cycle is term used to describe that action of taking a step and is broken down into two phases, swing phase, during which the foot is off the ground and swings through to start the next step and stance phase, when the foot is in contact with the ground, stance phase then breaks down into three phases, heel strike, midstance and propulsion.

Contact Phase

• The foot first comes into contact with the ground.
• Large forces need to be absorbed here.
• Contact phase can be at the heel, midfoot or forefoot depending on your running style.
• The most common area for initial contact is on the outside edge of the heel, and this can be called heel strike.
• Fatty tissue under the heel helps to absorb shock.
• It is the point of maxium impact in the gait cycle.
• 3-5 times your body weight of impact can occur.

Midstance

• The foot comes in full contact with the ground supporting the whole body.
• Weight transfers from the heel to the midfoot.
• The foot becomes flat on the ground.
• Natural shock absorption takes place through varying amounts of pronation.
• Weight and muscle activity is at its greatest.
• Midstance is the phase when most injuries are incurred.

Propulsion

The body weight is transfered onto the toes to push the body into the next step.

• The heel raises.
• Weight transfers to the ball of the foot.
• The Windlass Mechanism occurs.
• The foot becomes a rigid lever.
• The body is propelled forward ready for the next step.
• The ideal toe off should be centrally through the toes (between the big and second toe).

To figure out what type of running shoes you should buy, you first need to know what kind of feet you have. We offer a free of charge Video Gait Analysis service where we will advise you on the correct trainers for your foot type. All you need to do is run or walk on our treadmill for a few seconds. Please visit our youtube account to see the video gait analysis in action. Intersport Cheltenham

There are three different types of feet:

Flat Feet

If you're looking at your foot, you'll know you have flat feet if you don't see any arch. The bottom of your foot, from your toes to your heel, is completely flat. If you do a footprint test on a wet piece of paper, your print will look like a foot-shaped blob. You won't see an inward curve from your big toe to your heel.

If you're flat-footed, you're most likely an overpronator, which means that your feet roll inward when you run.

You will probably need a running shoe that maintains your stability. "Motion control" and "stability" shoes are likely to be best. In addition to motion-control shoes, some flat-footed runners also need to wear orthotics (custom-made shoe inserts that correct foot issues, however orthotics should not be worn with Motion contro; or stability shoes).

High-arched Feet

You should be able to easily determine if you have high arches -- you'll notice a high and definite arch on your foot. If you do the footprint test, your print will curve inward, making the middle part of your foot look very skinny. When you push your hand against the bottom of your foot, your arch will stay rigid.

If you have high arches, you probably supinate or underpronate, which means your feet roll outwards as you run. It's very important that runners with high arches periodically re-measure their feet because running will cause their arches to gradually fall, making their feet longer.

You need to look for flexible shoes with a soft midsole that absorbs shock. When buying running shoes, ask for shoes that are flexible" or "cushioned" .

Neutral or Normal Feet

If you've examined your foot or your footprint and it doesn't look flat-footed or high-arched, you most likely have a neutral or normal foot. Your footprint will have a noticeable curve inward, but not by more than 3/4 of an inch.

As long as you pick a running shoe that doesn't counteract your foot type, you shouldn't encounter any problems. This is the most common type of foot, and it's also the least susceptible to injury provided it's outfitted with proper footwear.

If you have normal feet, you can choose from a wide variety of running shoes, including ones made for neutral runners or those with slightly flat-footed or high-arched feet. Don't pick running shoes that have a lot of stability or motion control.

The Windlass Mechanism

The Windlass Mechanism is the way the leg is structured so that all the muscles & ligaments, from the toe to the hip are inter-linked & work together.

For the Windlass Mechanism to be working properly the foot needs to be in a neutral position.

To check-

Stand with your feet square & relaxed.

Ask a friend (without any assistance from you) to wiggle your big toe.

Ideally when the toe is wiggled, you should see movement under the arch where the Plantar Fascitis tendon will strain all the way up the leg to the hip. This means the Windlass Mechanism is working & all the tendons, ligaments & muscles are perferctly aligned & would suggest you're a neutral runner.

If there is movement up the leg but not all the way to the hip, it would suggest that you're naturally standing in a slightly over-pronated position. This means that without suppotive shoes, whilst running, something along the length of the leg will compensate for the excessive roll & may cause pain in or around that area. To correct this, roll your foot slightly outwards & ask your friend (again without any assistance from you) to wiggle your big toe. By doing this, you're effectively offering support under the arch as a supportive shoe would.

If there is no movement, your either a severe over pronator or have had an injury to the area maybe a break or a calcium buildup in the form of bunions.

Coaching tips & hints

One of the benefits of running is that it is an activity which can fit into even the busiest of lifestyles. An early morning run is a great start to the day, but make sure that you pay attention to warming up properly to avoid unnecessary injury.

Weather conditions can affect the time of day that you should run. In Summer, avoid running in high temperatures - early mornings and evening are the best time. In Winter, make the most of the daylight for your running time - if you choose to run at night, make sure that you wear reflective clothing

Running with someone can be motivating and the incentive that you need to maintain a good running programme. Your running partner should be of the same or similar standard as you so that you can progress together. Joining a local running club is a great way to get into running and meet new people. Many clubs have coaches available to give advice on running techniques.

As a beginner you should only be running at a steady pace and should not be gasping for breath and pushing yourself too hard. If you are running with a partner you should still be able to talk to each other. As a beginner, you shouldn't be running every day! Three to four times a week is a good guideline but challenge yourself to run for longer each time. On the rest days in between, undertake moderate exercise.

Forty-five minutes is the so-called standard for aerobic exercise. Of course you can do a little less or a little more, but as a general rule, this is the ideal length of time in order for your body to feel the physiological benefits. Even if you don’t run a full forty-five minutes in the beginning, this is a good target to aim for.

Remember: Running does not mean sprinting! You should run at a comfortable pace and devise a training programme to suit your individual requirements and overall goals. Practice and develop your breathing techniques as you run.