Want to run faster while exerting less effort? Sound too good to be true? Let us explain!
A runner’s speed is intimately linked to the power produced by each muscle. Most training programs try to strike a balance between duration, intensity and frequency to increase a runner’s strength or endurance. This is all well and good, but it’s just as important to focus on the basic building blocks within the skeletal muscle tissue. As Jay Dicharry, DPT wrote in the 2013 book Anatomy for Runners, “The position of muscle has a profound impact on its ability to generate force”. Today, we’re going to break down the anatomy of a muscle and how subtle changes to the position of your joints can positively impact your muscles ability to generate force.
Skeletal muscle is composed of two primary fiber types, thick filaments (myosin), and thin filaments (actin). These fibers alternate in an interlocking mechanism called a sarcomere. To better visualize a sarcomere, extend your arms in front of you so that the fingertips of each hand are tip-to-tip. Notice the flat open surface of each open palm. Now, slowly slide the fingers of your left hand into the spaces between the fingers of your right, like a zipper. With fingers interlaced, experiment between very little overlap of left and right fingertips, to almost full overlap where the fingertips of one hand practically reach the base of the fingers of the other hand. This sliding mechanism of little overlap to full overlap is very similar to the mechanism of actin and myosin sliding past one another. When fibers only slightly overlap (think fingertips only), or when there is too much overlap (full interlacing of the fingers), it’s tough to generate rapid energy production. The best scenario to produce rapid energy production is that sweet spot in the middle, where actin and myosin overlap, somewhere between barely touching and full compression.
So, how do we ensure that our muscles are functioning in their most optimal lengths?
Muscle length is impacted most strongly by joint position. To perform a standing jump, you would most likely ready your stance by slightly bending your knees to increase minor flexion of your lower limb joints. Now, think of performing this standing jump from a full squat. When you squat down many of the lower leg joints flex and decrease angles, compressing muscles and creating lots of actin and myosin overlap. On the other extreme, perform a standing jump from an upright stance with locked knees, the muscles lengthen and fibers have less overlap. The squat vertical jump requires far more effort to extend from a compressed position, and the upright, while the locked leg jump doesn’t produce very much force. This is an example of sliding filaments, and how joint position and muscle length contribute to an ease of force production.
While running, muscles undergo a variety of given lengths. This expansion and compression of tissue can be subtly altered with certain features of conventional footwear:
Toe Spring:
Toe spring is the component of running shoes that roll the tip of the sole up from the ball through the toes. This feature lifts the toes into dorsiflexion, or ‘up’. When toes are fixed in a dorsiflexed position, muscles on the bottom of the foot are lengthened from their proper alignment and muscles on the top of the foot end up shortened or compressed.
Correct Toes Tip: Purchase shoes that do not elevate the toes, allowing for shortening of the muscles on the bottom of the foot, and lengthening of the muscles on the top of the foot. You may also benefit from the use of a Metatarsal Pad, or want to try the Toe Extensor Stretch.
Heel Elevation:
Heel elevation is not just in dress shoes. Most conventional athletic and running shoes are constructed with more heel cushion than forefoot cushion, effectively elevating your heel. This feature compresses calf muscles, allowing for too much fiber overlap.
Correct Toes Tip: Purchase shoes that are “Zero-Drop”, or flat, to allow your calf muscles to extend to their full potential with each step you take.
Pointed Toe Boxes:
Pointed Toe Boxes are an aesthetic feature, carried over from dress shoes. While we might like the look of a pointed running shoe, the small shape squeezes toes inward, particularly impacting the muscles that control the hallux, our big toe.
Correct Toes Tip: Purchase shoes with a naturally shaped toe-box, allowing the Hallux to maintain straight alignment. Check out our recommended shoes.
Of course, running performance will be dependent on a variety of factors, but it’s never too late to look at the basics. Get the most force production from each muscle by focusing on the alignment of joints and muscles within natural footwear. Maintaining natural length-to-tension relationships in your muscles will allow you utilize optimal construction to maximize your effort.
