Strength and conditioning professionals are more likely to maximize peak performance and prevent injury if we understand and are well versed in a number of biomechanical factors. By studying the movement and structure of the human body, we are better equipped and therefore more likely to provide the most effective training programs for the needs of the individuals and teams we coach. Being well versed in biomechanics also better enables a strength and conditioning coach with the knowledge to educate the student-athlete on why a certain exercise was selected and/or why it should be performed in a specific way.
Neural control is the first biomechanical factor. Strength training enhances the brain-body coordination of an athlete. By practicing an exercise, the athlete's brain is firing up the correct muscles to achieve the movement. After an athlete improves at an exercise, the movement becomes more automatic and the neural adaptations are less significant (Haff, 2016). A strength and conditioning professional should consider that quick gains are more likely at the beginning of a strength and conditioning program. The brain is learning how to generate more force through neural control and this should be be factored into goal setting and progressions. A strength and conditioning professional might also communicate with their athletes that progress will be more gradual as time goes on so they are not disappointed from unrealistic expectations due to big gains early.
Muscle cross-sectional area is a biomechanical factor and major predictor of force production. A large muscle cross-sectional area has great force generation capacity and correlated with higher sprint performances (Tottori et al., 2018). A properly designed strength program can increase the cross-sectional area of a muscle so when that athlete improves their muscular cross-sectional area they will most likely also be able to produce more force potential in their sport mainly with sprinting.
Muscle fibers, and how they are arranged, is another biomechanical factor. The force of muscles varies significantly due to the variation in the arrangement and alignment of muscle fibers (Haff, 2016). Differences in genetics and training contribute to differences in strength and speed amongst two athletes that look the same. A strength and conditioning professional working with a basketball player should focus on exercises that recruit fast-twitch muscle fibers: plyometrics, Olympic lifting, sprinting, explosive weight training, etc. A long distance runner is nearly the opposite because their sport requires more recruitment of slow-twitch muscle fibers.
Muscle length is another one. A muscle at its resting length generates the most force because the actin and myosin filaments are next to each other and a maximal number of crossbridge sites are available (Haff, 2016). On the contrary, when the muscle is stretched beyond its resting length, a smaller proportion of the actin and myosin filaments are next to each other. The muscle cannot generate as much force due to a lower number of available crossbridge sites.
Joint angle is next. All body movements take place by means of rotation around a joint or joints (Haff, 2016). A strength and conditioning professional must consider the type of exercise, body joint, muscles used, and the speed of contraction when selecting exercises for a training program. Certain exercises are more sport-specific than others so it's best if a strength and conditioning professional looks at ways to create training programs that are consistent with the demands of the sport.
Muscle contraction is also on the list of biomechanical factors. More specifically. velocity. The force potential of a muscle declines as the velocity of contraction increases (Haff, 2016). Technique can make the best of this relationship so it is essential a strength and conditioning professional instructs their athletes with the appropriate cues. For example, as a vertical jump begins, the arms swing upward and therefore enables them to generate higher forces for longer times (Haff, 2016).
Joint angular velocity, or the rate of change of joint range of motion, makes the cut too. In concentric muscle action, the muscle shortens because the contractile force is greater than the resistive force. In eccentric muscle action, the muscle lengthens because the contractile force is less than the resistive force. In isometric muscle action, the muscle length does not change, because the contractile force is equal to the resistive force. A strength and conditioning professional must carefully consider when and where to incorporate concentric, eccentric, and isometric exercises.
Strength-to-mass ratio is an important biomechanical factor to consider too. This ratio compares muscle (strength) to body weight (mass) and is essentially a measurement of relative strength. The ratio is critical because it reflects an athlete’s ability to accelerate his or her body. If an athlete improves their strength-to-mass ratio, they will improve their acceleration. A strength and conditioning program should increase strength by a greater percentage than mass.
Body size is a biomechancial factor too. The reason smaller athletes are often stronger than larger athletes is because their muscle’s maximal contractile force is more proportional to their cross-sectional area (Haff, 2016). Furthermore, as body size increases, the body mass increases faster. Therefore, given constant body proportions, the smaller athlete has a higher strength-to-mass ratio than does the larger athlete (Haff, 2016). Smaller athletes will progress faster than a larger athlete so a strength and conditioning coach should consider this when designing programs and coaching athletes. If two athletes are partnered up in strength training, but both are different sizes, the progressions of their respective programs are best programmed at different rates.
Those are some of the most important biomechanical considerations a strength and conditioning professional must factor into a program for athletes in any sport. Like in any industry, lots of factors are considered when leading others. Since the strength and conditioning is leading others, the mind of a coach equipped with this knowledge is likely to get great results if they can apply the science to real life.
Haff, G.G., & Triplett, N.T. (Eds.). (2016). Essentials of strength training and conditioning. Champaign, IL: Human Kinetics.
Tottori, N., Suga, T., Miyake, Y., Tsuchikane, R., Otsuka, M., Nagano, A., Isaka, T. (2018). Hip Flexor and Knee Extensor Muscularity Are Associated With Sprint Performance in Sprint-Trained Preadolescent Boys. Pediatric Exercise Science,30(1), 115-123.