Efficiency can refer to your body’s ability to achieve the highest level of performance with the lowest risk of energy. Here’s how your body ensures you have it when you’re walking.
You not only eventually learn to walk without giving your gait a second thought, but you learn to do so efficiently. This only comes about due to a series of intricate interactions between your nervous and motor systems.1 Your nervous system automatically assesses visual, proprioceptive and vestibular sensory input to inform your motor system on the most efficient moves to make with each and every step.
Efficiency Explained
Efficiency has a broad definition when it comes to movement, but one way to view it is your body’s ability to gather, store and release energy to achieve the highest level of performance with the lowest risk of injury. When you walk, you gather energy from the impact force of your foot hitting the ground. You then store the impact force as potential energy and then release it as elastic energy.
As outlined in a previous post on Barefoot Training, the components of deceleration, balance and acceleration must work in tandem for your body to enjoy the highest level of efficiency. A good way to understand the way it works is to think of riding a bicycle up a hill.1,2
Deceleration is where your body takes in the potential energy, the same way the bicycle gathers energy as it heads up the hill. When walking, decelerations is where eccentric contractions take place as your foot hits the ground and the foot’s inverters load energy taken in from the impact force.2
The energy is stored and ready to be released once the bike hits the top of the hill, or you’re standing on a single leg during the gait cycle. The energy is then released as elastic energy, where concentric contractions occur. Here you move forward in the gait cycle or the bike goes zooming down the hillside.1,2
CAN USE KINETIC ENERGY CURVE SLIDE AGAIN HERE or NEWMANN’s bike illustration from p. 638 (reference 1 or 2)
How Your Gait Achieves Efficiency
As explained in our introductory post on gait, your body uses a series of five movements to ensure your gait is efficient. These movements work together to ensure your center of mass (CoM) moves through space in a flattened pathway. This flattened pathway keeps you moving forward without excessively jerky, up-and-down movements that waste energy. But the flattened pathway isn’t the only part of the efficiency equation.1
While you may feel like you’re walking at a steady pace moving forward, your body actually slightly speeds up and slows down with every step you take. It can then best utilize energy the same way it’s used on your bicycle ride up and down the hill.
When your supporting leg is in front of your body’s CoM, your body ever so slightly slows down. When the supporting leg is behind the CoM, your body’s speed slightly increases. Your body thus reaches its lowest speed at midstance, after your body has “climbed up the hill” on its supporting leg. It reaches its highest speed once it has the support of both legs, or after “zooming down the hill” from the initial supporting leg.1
NEWMANN’s ILLUSTRATION from p. 638
Speed as Factor
One more consideration is efficiency during different walking speeds. The five integral gait movements automatically adjust to obtain the highest level of efficiency regardless of your speed. You can spot-check this with a slow walk, which leaves your lower extremity joints fairly stiff and inflexible. Increase your speed to a run and you’ll note an increase in knee and hip flexion to better absorb shock.3
While the transfer of energy helps to ensure you’re walking in the most efficient manner possible, that alone is not enough to keep you moving forward. Your muscles play a huge role by supplying enough energy to generate the force to move your forward. Our next installment in our series on gait will explore your muscles’ role in greater detail.1
REFERENCES:
- Newmann D. Kinesiology of the Musculoskeletal System. 2nd ed. St. Louis, MO: Mosby Elsevier; 2009.
- Splichal E. Application of Barefoot Science in a Rehab Setting An Evidence-Based Approach. Presented as a seminar topic by Evidence Based Fitness Academy; April 26, 2014.
- Michaud TC. Human Locomotion: The Conservative Management of Gait-Related Disorders. Newton, MA: Newton Biomechanics; 2001.