With growing evaluation of anatomy and function the more we can appreciate the designed (or adapted) system. From our head to our shoulders, knees, and toes (knees and toes) there’s an interesting progression that our body navigates from rigidity to flexibility and again back to rigidity. It should make sense at the most basic level, too. At the point of impact you’ll want a rigid system, designed to withstand the instantaneous forces of the foot meeting the ground. Almost immediately your entire body becomes flexible–from your foot pronating to your knee and hip flexing. This flexibility allows us to absorb high rates of loading and store energy for our preemptive explosion at push off.
Deviation from ‘the norm’, whether it’s due to weakness, tightness, sloppiness, or your bony structure, will affect the entire system. Of the previous reasons listed all but one (bony structure) is under your control. We all want to be faster, which usually equates to more miles, more speed workouts, more everything… more everything but refining the system. Yet, most of us slack on the items that can procreate speed without increasing run volume, frequency, etc. In fact, refining the system can not only improve speed, but also reduce your risk for injury–particularly for master runners. Think about it. You can move BETTER to waste less injury and maximize efficiency without having increase training stress. Win-win.
The goal of push off phase is simple: provide your body a rigid leg to transfer energy into the ground. Deviation between your spine and foot can all compromise the rigidity of your leg. Without a properly aligned leg at push off you’ll leak energy through unintended movements. A foot that fails to supinate or a knee / hip that fails to full extends are all deviations from ideal position. This all happens simultaneously, but let’s break it down into pieces.
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Your closed pack position at the knee is terminal extension, or when your knee is locked into extension. With your knee fully extended or straight, you great a very rigid lever for transmitting force down the leg and into the ground. A straight knee is terrible for shock absorption (ie heel striking), but is great at push off. Generally, the inability to achieve full extension is reserved for those with extreme tightness or prior surgery’s that didn’t result in fully recovery; however, we can still see runners failing to achieve full knee extension for another reason. Simply put—if you’re unable to achieve full hip extension it’s likely that your knee will follow suit. This is a general reminder that your whole body moves together and you’ll rely on your weakest link.
In all, you’re dealing the cards your dealt. Luckily, most of us fall into a grey area that allows us to dictate our anatomy through selective stretching and strengthening. The take home message is simple. In a sport with extraordinarily high injury rates you’ll need to find a better means for improving speed and durability. Historically, runners seek speed through harder, longer, and more frequent workouts. And although you may reap benefits, you’re certainly opening the door for injury. Dedicate yourself to better movement and a weekly minimum of 60 minutes to improve upon deficiencies.