Movement: One of the most fundamental human movements, running is nevertheless subject to a large number of pathologies. Any existing inflexibilities or postural problems can cause problems in the running stride and increase the risk of repetitive strain injuries. Basic running form should include the following - hips that point forwards and not excessively downwards; arms at your sides bent to 90 degrees at the elbows; arm swing primarily forward and back with some - but not excessive - rotation across the body. Do not clench your fists or incline your torso too far forward. Be sure to land each stride with bent knees. The heel should rise above the knee on the recoil of each stride, while the knees should move predominantly forward on each stride. Whether to land on your heel or forefoot is beyond the scope of this explanation - but if you do experience pains or discomforts while running, you should examine which form of striding may be more appropriate for you.
Caution: Common problems with running include running completely upright, overstriding - that is, landing with your foot in front of your hip rather than underneath, and cycling your arms only forwards and backwards with no rotation (and alternatively, at the other end, moving the arms too far across the body).