Biomechanics
Generally, as a long distance runner your highest concern is to conserve energy. Avoid using your large muscles groups, like quads and hamstrings to power your way through the entire distance, or your muscles will run out of glycogen very soon. The key is to turn off your muscles as much as you can and rely on other means to get the forward motion.
Cadence
Short, quick steps and a circular motion of the feet are key. Increase your leg turn over or cadence to 180 steps a minute. It sounds like falling over your own feet but trainers and world class elite runners alike agree that a high leg turn over offers significant advantages for endurance runners:
- the body moves in a fluid motion, using momentum for the forward motion rather than hamstring to push off and the quads to catch the impact on when landing;
- smaller steps mean less effort overall as you move your heavy torso much less to compensate for the curve of each step. The reduced impact on landing results in less potential overuse injuries like runner's knee;
- a fast leg turn over doesn't give the tendons, e.g. arch and Achilles, enough time to fully stretch but the quick ground strike and push off makes full use of the elasticity within the tendons.
World class runners running at a pace of 3mins/km (roughly a 2:06 marathon finish) have a stride length of almost 2m at a cadence of 180 steps/min. If the cadence were only 120steps/min to achieve the same speed a stride length of close to 3m would be necessary!
Gait
Your legs should describe a circle as you go through every step. A circle minimizes the effort necessary:
- hip flexors are used to quickly lift your leg out in front;
- foot strike should be under your torso;
- glutes are used to create forward motion and follow through (not hamstrings!).
Avoid the flat tire gait, i.e. having too much bend in the knees and using your quads to hold you up. That tires out your muscles unnecessarily.
Avoid the pyramid gait, i.e. describing a triangle with your legs and landing with your leg stretched out in front it will only make you brake on every step and then accelerate again. That costs way too much energy and puts unnecessary strain on your joints.
Posture
Stay erect from the hip upwards and lift up in the chest. Lean only slightly forward with your torso, don't lean too far forward from your hips or your glutes won't work as well, instead lean forward from the ankle and stay erect. Well, and stay relaxed. It's all about being able to stay in this position for a long time.
What you want to achieve is to move your upper body forward from the ankles (while staying erect), you should feel a slight stretch in your hip flexors in the beginning (if you are as tight as I am). This is the most difficult part.
Try the following. Stand (zero miles per hour) upright, then lean forward from your hip, upper body still straight, move forward further until your stand becomes unstable. What happens? You will eventually make a step forward not to fall on your face. This is how running should be. You fall forward because your centre of gravity is in front of your feet. Your legs just follow. Lift your legs and move it under your body to support yourself. Momentum will move your body mass and you become unstable again ... Hurray, we are running.
Depending how far you lean forward you change your speed.
If you are running relaxed, then you are running perfectly. Your muscles are not working as hard as they used to and it takes some of the impact of your joints. But don't expect your cardio system to get a break from this. It's still working hard. Moreover you will have to have strong core muscles.
Kick back
How much kick do you get from throwing your leg back and up? Pushing off from the ground with a strong kick back makes you even faster.
Elbows
Elbows should be back, then your hips will come forward to balance you. Think that you have a tail attached to your rear end and then pull it through your legs and up in the front.
Your arms should start at your side then go back from there. Your arm swing should not go past your side. Your elbows should be slightly bent so that your hands are at about waist level.
Think in terms of force and counter force: when you swing your arms forward your body gets pushed backwards. Focus on swinging your arms BACK, naturally they will swing back to the front.
Open up your chest as you are bringing your arms back. (remember
all the breathing/oxygen talking we did?)
Finally a topic where it is not bad to be stiff. With just the right amount of stiffness we can use the tension in the muscles and tendons to bounce off and run more efficient. Too stiff increases the risk of injury, too much flexibility doesn't give you this spring-like effect and we have to use muscles to do the work.
An excellent tutorial about efficient running is available on DVD from Evolution Running.