With an increase in efficiency in movement comes decreased time to produce the movement, as well as an increase in the force that is able to be generated. Without any change at all to cardiovascular output, efficiency and endurance, if we simply increase the ability of the muscle to produce more force with less energy demand, in a shorter period of time, not only does power in the pure sense increase, but overall endurance improves as well.
There are a lot of standardized tests to assess muscular power in athletics but the two most commonly used are the Sargent Jump Test and the Stair Sprint Test. The Sargent Jump Test was developed by Harvard’s gymnastic coach, Dudley Sargent in the early 1900s and it is still used today as an assessment of power output and maximal vertical height (it is also known as the Vertical Jump Test). There are some variations to the test. But in the most basic form, the athlete stands next to a wall sideways, reaches up with the arm closest to the wall fully extended, keeping the feet flat on the floor, and the highest point at which the fingers tips reach up on the wall is marked. Then the athlete performs a maximal vertical jump marking the point at which the finger tips reach at the peak of the jump. This is performed 3 times and the average of the three is calculated.
The Stair Sprint Test has been found to be highly reliable and valid for measuring explosive power and is endorsed by the American College of Sports Medicine. In this test, the athlete is timed while sprinting a given distance on ascending stairs. The force is the athlete’s weight and the time is how long it takes to ascend the given distance. In this particular test, the athlete improves, i.e., increases his or her power output, by decreasing the time it takes to ascend the stairs.
Using the Step Up Test to assess an athlete’s movement pattern, we can see that when this particular athlete ascends (steps up) the right hip falls into an adducted position and the right femur rotates internally. When this occurs, two things happen: First, there is an immediate loss of energy in the kinetic chain. Second, these changes in the stepping up action alter the length/tension relationships in the lower body. Since this test is designed to demonstrate efficiency of movement (or lack thereof) and a corresponding maximal use of energy, each of these occurrences has a dramatic impact on power output. In the position in which we see this athlete, the muscles cannot contract maximally and much of the explosive power she needs to climb the stair is lost. Test results show a longer length of time to complete the task or movement as a result.
In sports, speed and power are sometimes used interchangeably. Speed is defined as distance traveled per unit of time. From a calculation standpoint, the only difference between a speed calculation and a power calculation is that the power calculation takes the athlete’s weight into account, or the weight of an object that is being moved by the athlete. We can easily see then the impact that abnormal movement or pathokinematics has on power. Therefore we can deduce that pathokinematics in this, or any, athlete would similarly impact speed due to the loss of energy in the kinetic chain and the inability of the muscles to contract maximally and generate the greatest amount of explosive power in the shortest amount of time.
Flexibility is simply the ability to move your muscles through their full range of motion. Factors that influence flexibility include:
Since the late 80’s or early 90’s there has not been much research conducted on factors that influence flexibility or how we can influence flexibility with training. Even so, in a clinical and athletic training setting we do see the impact that pathokinematic movement patterns have on flexibility. If, for example, an athlete has a significant lateral shift with a squat, then this movement pattern is going to be carried over to every squatting motion he performs, outside of sports and during sports. This includes such activities of daily living as sitting down on a chair, sitting on his bed, sitting and rising from the commode, and getting in and out of a car. As a result of imbalances in the body during this movement alone, overall flexibility will be greatly affected, which of course translates to performance. We know that flexibility is critical for all sports and many athletic trainers, coaches and other professionals who work in the field of athletics believe that for the total time spent, flexibility training may in fact be the most important and the most beneficial activity across all sports.
This athlete, performing the squat test, is clearly shifting to the right, as shown previously. He is also unable to keep his back in alignment while bearing most of his weight on the right side. This shift is lengthening the hamstring and the quadriceps on the left and shortening them on the right, as shown. This means that over time, he is likely to become less flexible on the right side of his body than he is on the left. This further reinforces the shift, making it worse over time in a vicious cycle. In addition, due to this particular abnormal movement and the associated inflexibility and abnormal force attenuation it causes in the lower kinetic chain, it is likely that this athlete will also become much less flexible in the lumbar spine, and eventually also in the thoracic and cervical spine. This can lead to imbalances in running gait, excess (and inefficient, energy zapping) motion in the hips, pain in the L5/S1 region of the lower back, pain traveling up the back into the mid and upper back and neck, and compromised power output through the transmitting core.
A couple of last points related to flexibility in this example that are worth noting is first that as a part of his abnormal movement or pathokinematics, this athlete’s arms move forward as he squats. He does this as a compensatory strategy in order to prevent himself from falling over. So, not only is his inflexibility adding to abnormal force attenuation, it also adds to a loss of balance as well. Again, this further increases the loss of kinetic energy and ultimately decreases the efficiency of the entire system. Over time, this athlete is likely to become more and more inflexible in the hip flexor group as well, which is critical for football and other activities of daily living such as walking and running as discussed above. These factors related to flexibility can ultimately lead to other kinds of injuries and pain with activity down the line. Of course we can also easily see the performance impact limited mobility has on speed, power and endurance on the football field.