Justin from 70sbig.com has a post on shin splints.
Even though most take it for granted, running is a skill and just like with all skills you can do a lot wrong.
When going through this “heel strike, forefoot flop”, the ankle is moving into plantar-flexion (toe down) while trying to maintain dorsi-flexion (toe up). The resistance of the movement causes the muscles that maintain dorsi-flexion to eccentrically act — they are stretched when still trying to contract. This is the same thing that happens to the hamstrings in an RDL: the hip goes through resisted hip flexion yet the hip extensors (the hamstrings) are resisting the action and preventing you from just falling over. Let’s substitute the terms and focus on the ankle while running: the ankle goes through resisted plantar flexion yet the dorsi-flexors (on the front of the shin) are resisting the action and preventing the foot from just falling forward.
If you paid attention to your muscle mag lore, you know that eccentric muscle action causes the most damage to muscle fibers and as a result more soreness (since the muscle fibers are being ripped apart while trying to stay contracted). The muscle on the front of the shin that cause dorsi-flexion (pulling the toes up) is primarily the tibialis anterior. When heel striking, it’s going through hundreds of repetitions of damaging eccentric action. The damage occurs along the entire attachment site of the tibialis anterior, which for this muscle is along the entire tibia (shin bone). That’s why it’s called “shin splints” since the entire shin is painful afterwards.
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