You may haver heard the term biomechanics before, especially as an athlete. But what is biomechanics?
When we think about how our body moves, we often think about moving in a simple sense, moving in the forward direction. In other words, if we are standing up, we think about walking straight ahead with our legs moving front to back in the direction that we are going.
However, movements of the body are actually quite complex and can occur in a 360° manner. In addition to moving forward and backward, we can move side to side and rotate different parts of the body or during different actions as well.
All of our joints move through different angles as we move. Additionally, our movements are accompanied by forces. When we land on the ground when walking and running, for example, the body applies a force into the ground that can be upwards of three times our body weight.
In return, the ground applies a force back to the bottom of the foot in equal magnitude but in the opposite direction. Biomechanics is the specific arm of science that describes the different ways that the body can move, and the different forces produced and experienced by the body.
In this article, we will cover the biomechanics definition, as well as basic biomechanical principles of human movement. More specifically, we will cover:
- What Is Biomechanics?
- Primary Elements of Biomechanics for Sports Performance
Let’s dive in!
What Is Biomechanics?
Although many people have heard of biomechanics, our general understanding of what biomechanics entails is usually vague.
So, what is biomechanics exactly?
Biomechanics is defined as the science of body mechanics or how the different tissues of the human body (or animal body), such as the muscles, tendons, bones, ligaments, and joints, work together to produce movement.
In this way, the field of biomechanics investigates not only the anatomical structure of the bones, joints, muscles, and connective tissues and the resultant movement that they can produce but also how these movements affect the body.
Principles of biomechanics are used by kinesiologists, biomechanists, and exercise and fitness professionals to study exercise performance as well as everyday healthy and dysfunctional movements.
According to the American Society of Biomechanics, the biomechanics definition involves the dynamic interplay between both the mechanics and the biological systems of a living organism.
Biomechanists who focus on exercise performance and athletic activities look to ways in which studying human biomechanics can improve performance and or make physical activities safer and more effective.
The scientific discipline of biomechanics falls under the larger umbrella of kinesiology, which entails all aspects of human movement, including anatomy and physiology, motor control of movement, sports psychology, training principles, and the mechanics of movement itself (biomechanics).
Primary Elements of Biomechanics for Sports Performance
There are a variety of sub-disciplines that fall under the general science of biomechanics, such as statics and dynamics.
However, the main elements that constitute biomechanical science pertinent to studying biomechanics for exercise and sports performance are kinematics and kinetics.
Kinematics is the sub-discipline of biomechanics that describes motions or how the body actually moves in a three-dimensional space.
The three planes of the body and the three planes of movement (sagittal, frontal, and transverse) help define exactly where in space different limbs of the body are relative to one another so that human movements can be described, measured, and compared.
Examples of body movements at joints include flexion and extension, abduction and adduction, and internal and external rotation.
By studying the kinematics of an adept athlete, biomechanists can identify likely movement patterns that aid performance during a sport, presuming that elite athletes are moving in ways that maximize potential physical performance.
For example, someone who works in the field of biomechanics might conduct a laboratory or field-based study of top marathon runners such as Eliud Kipchoge, and examine the exact joint angles, velocity, and acceleration that he displays during his cruising speed during a peak marathon performance.
This information can then help create running form advice for other distance runners, with the belief that the movement pattern and joint angles that Kipchoge runs with must be among the most efficient and ideal for running economy.
For example, Kipchoge has a fast cadence, which enables an efficient stride length. Rather than overstriding like many recreational runners, in which the foot of the leading leg is placed too far in front of the body’s center of mass, Kipchoge runs with a shorter stride length.
This allows his tibia to be nearly vertically relative to the ground at foot strike, enabling him to land on this midfoot rather than his rearfoot, as is the case with most overstriders.
When you overstride, instead of the angle between your knee and tibia being closer to 90° at foot strike, it is an obtuse angle with your tibia no longer running perpendicular to the ground. Instead, it is outstretched in front of you, causing you to land on your heel.
This reduces your running economy or compromises the energy efficiency of your running stride because some of the forward momenta is lost when you land on your heel. This is because there is a horizontal and vertical component to your velocity.
Your heel is pressing downward and forward simultaneously into the ground, which means that your ground responds by pressing upward and backward into your heel. However, because you want to be running in the forward direction, receiving a backward force is counterproductive.
Similar principles can be applied by studying the movements of athletes of any type of sport.
Ultimately, investigating the differences between the body mechanics of top competitors and novice or recreational athletes of the same sport can help identify key areas in which athletic performance can be improved.
Areas in which the movement patterns and body mechanics vary significantly between athletes of different levels are likely to be the most important areas to focus on for improvements.
As another example of the benefits of studying kinematics of human movement for sports performance, biomechanists can study how cycling performance changes with different bike geometries.
The aerodynamics of a bike can significantly affect your cycling speed because the wind resistance is the major force opposing forward movement on the bike when cycling on flat land.
The less aerodynamic you are, or the more surface area that your body has in the frontal plane (side to side), the greater the air resistance you will have to overcome.
At the same time, differing seat post angles and handlebar angles will affect your body posture on the bike and the angles at which your joints are moving through the pedal stroke and are able to generate force.
Biomechanists can use principles of biomechanics to study movements (kinematics) and forces (kinetics) during cycling to determine optimal bike fit and bike geometry for cyclists of different racing disciplines and ability levels.
Kinetics works hand-in-hand with kinematics, but rather than describing motions themselves, kinetics studies the forces that act on the body during these motions.
Essentially, the study of kinetics helps determine the most efficient and safest ways to optimize the movements of the body.
Kinetics findings during exercise performance help capitalize on the mechanical advantage of lever systems created by bones and joints to maximize the potential force generation and minimize any unhealthy torque or stress on the joints and bones.
By looking at the composite of kinematics and kinetics, or the resultant body mechanics, biomechanists can also deduce ways to help reduce the risk of injuries.
For example, they can examine ways in which forces are acting on the body during physical activity and then experiment to determine how changing the movement pattern (kinematics adjustments) changes and hopefully decreases the forces acting on the body (kinetics) or forces that must be generated by the body.
Alternatively, even if it is not possible to change the movement pattern and the resultant forces, biomechanists can work with engineers to change the equipment to better suit the human body during exercise to reduce the magnitude of these forces, stresses, or strains.
An example here would be progressing running shoe technology to better help absorb the impact stresses of landing on the feet.
By studying exactly where on the foot most runners land, the typical angles of pronation during the running gait, and the movement of the arch of the foot during the running stride from the heel-to-toe transition, the design of the cushioning and support of elements in the insole, midsole, and outsole of a shoe can be optimized to reduce running-related injuries.
The field of biomechanics is far more complex than what was covered here, but this is a window into the biomechanical study of human movement as it pertains to exercise and athletic performance.
If you are a runner and improving your running form is high up there on your list of priorities, take a look at our running form guides to help you start to improve your running economy right away: