Gaining flexibility allows for a greater range of motion and a greater ease of motion. These are all good things for a runner, if that increased flexibility is balanced with stability and muscle coordination. Many runners might improve their flexibility, but they never teach the muscles to fire and engage in this new range of motion. What is left can be perhaps a higher knee lift, or longer hip extension, but also a muscle contraction within those positions that is too weak or uncoordinated to take full advantage of the improved flexibility. What is needed is an increase in functional flexibility.

Functional flexibility is the ability to efficiently and strongly engage muscles through the full range of motion of a joint. The length-tension relationship of the muscle will determine how much power can be generated, where the strongest force is typically in the mid-range of motion (for example, if doing a bicep curl, the strongest force from the bicep will typically be when the arm is around 90 degrees). For some, once the muscle is outside of that mid-range of motion the power output of those muscles dramatically decreases. For others, who are perhaps more athletic, they can still exert a strong impulse well outside of their mid-range of motion.

For runners who want to increase their functional flexibility, you are looking to learn how to engage your muscles when the leg is put outside of its mid-range of motion (so more flexed or extended than normal). A great introduction, and beginner ‘strength’ exercise, for this is to apply manual resistance while in basic stretch positions. For instance, contracting your quadricep against the pull of your arm when in the ‘heel to glute’ quad stretch position, contracting your hamstrings when in the ‘lying knee to chest’ stretch position, or contracting your calves when in a wall-push calf stretch position.

Start with light contractions for short durations in a light stretch position. As you get more comfortable and more coordinated, start increasing the intensity of the contraction for longer durations and in more extreme stretch positions.