Making The Jump

With the help of The Citadel’s Army ROTC department, Brennan Textor recruited Army contract cadets to participate in a study to investigate the relationship between jumping biomechanical characteristics and performance in the ACFT.

What do jump performance and the U.S. Army’s newest physical fitness test, the 2020 Combat Fitness Test (or ACFT), have in common, and how could this data be important to the Army and other military organizations?

In my thesis research I compared jump performance and force production in the takeoff phases of the countermovement vertical jump (as in jumping to make a basketball shot) and the standing long jump (as in jumping over a stream). Jump performance is how far or high a person can jump. Force production is how much force a person produces with the jump.

Jump performance is something that can be easily assessed, especially because jumping is a great measure for neuromuscular performance—strength and power as well as sport performance. Leg muscles produce an impulse that accelerates body mass. Whether in a high school physical education class, military recruiting station or basic training assessment, jump testing may provide an early indication of a person’s ability to withstand successfully the rigors of basic training or any exercise and help tailor training protocols to minimize injury.

The purpose of my thesis was to investigate the relationship between jumping biomechanical characteristics and performance in the ACFT. By investigating levels of bilateral symmetry between lower limbs, I attempted to determine how these differences might correlate to the ACFT.

With the help of Capt. Jason Dubyoski in The Citadel’s Army ROTC department, I recruited Army contract cadets to participate in the study. We created a makeshift lab on a Deas Hall racquetball court where cadets performed both the countermovement vertical jump and standing long jump. The force plates measured the ground reaction force of the cadets during the jump. I also measured jump height and took measurements of the left and right legs to help detect asymmetries, meaning I was able to see if the subjects were using one limb more than the other to push through the ground to create movement. I then compared the jump data to each of the cadets’ Army Combat Fitness Test scores to look for relationships between jumping biomechanics and ACFT performance. Specifically, I looked at maximum deadlift, standing power throw and sprint-drag-carry as well as the overall ACFT score.

The conclusion—there is a strong correlation between performance in the standing long jump and countermovement vertical jump, meaning if a cadet is able to perform well biomechanically, then the cadet is able to jump far, and vice versa. In addition there is a positive relationship between jump performance and the overall score of the ACFT, which indicates that performance in the maximum deadlift, standing power throw and sprint-drag-carry as well as the overall score can be predicted simply by jump performance.

The findings are important, especially to the Army, because the results help confirm that performance in the new ACFT is largely anaerobic and reflects lower-limb muscular strength and power capacities. It is unlikely that we would see the same relationships with the previous Army Physical Fitness Test, which focused largely on aerobic endurance.

Understanding these relationships allows us to better understand what components of fitness are reflected in physical fitness tests such as the new ACFT and may help the U.S. armed forces and other paramilitary units, such as fire departments and law enforcement agencies, to refine their readiness assessments and training for optimal fitness among their personnel. Additionally, the countermovement jump and standing long jump are fundamental movement skills, often learned through participation in K-12 physical education and youth sports. Poor jump performance, therefore, may indicate a lack of exposure to physical education or youth sport participation.

On my thesis panel were Health and Human Performance professors Capt. Christopher Sole, Capt. Ryan Sacko and Maj. Dan Bornstein, who are now collaborating with the Commandant’s Department to expand this project to track cadet jump performance, ACFT scores and injuries. Findings from this four-year longitudinal study could assist the college in improving current and lifelong fitness among our cadet population and may have implications for fitness and injury prevention among military and other organizations.

When I started working on my master’s degree, my goal was simply to graduate and start my career, but these three professors challenged me to complete a thesis as part of my degree, an idea that seemed impossible at the time because I had never been particularly interested in research. Now, having learned from professors actively engaged in research on fitness in the military, I am grateful for the opportunity to conduct research and work on publishing the results, in the hopes that we can contribute to the science of preventing injuries and improving fitness among our military service members.

Brennan C. Textor graduated in August with a Master of Science degree in Health, Exercise and Sport Science. A native of Raleigh, North Carolina, she received her Bachelor of Science as a Health and Fitness Specialist from East Carolina University in 2016.