Date of Award

August 2024

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Kinesiology

First Advisor

Jennifer Earl-Boehm

Committee Members

Hayley Ericksen, Brooke Slavens, Chris Cho

Keywords

Biomechanics, Landing, Military, Motor Competence, Performance

Abstract

Context: Reserve Officers Training Corps (ROTC) cadets are at high risk of injury, which results in high medical costs and affects the longevity of our future soldiers’ careers. Functional motor competence (FMC), defined as the coordination and control required to perform a wide range of motor skills, may be an underappreciated aspect of performance and injury in ROTC cadets because of how FMC is developed. Higher FMC has been speculated to be positively associated with better physical and neuromuscular fitness (power, dynamic balance, etc.), better performance on the Army Combat Fitness Test (ACFT), the Army’s standardized physical test, and protective biomechanics. However, the evidence to support these relationships in ROTC cadets is limited. The majority of the evidence on FMS is from child populations and not adult tactical athletes. The overall goals of FMC in child populations is very different than that of utilizing FMC in the ROTC. Evidence is needed to support FMC and its relationships to physical and neuromuscular fitness components, physical military readiness, and biomechanics existence in adult ROTC populations to support future investigations utilizing FMC for screening and intervention protocols.

Objective: The first purpose of this study was to determine if power and dynamic balance were predictors of FMC and to determine if the relationship was moderated by previous sport participation. The second purpose of this study was to identify the relationships between performance on the ACFT and FMC composite score. The final purpose of this study was to identify if FMC is related to landing biomechanics.Participants: 70 (49 males and 21 females) cadets were recruited from the Army ROTC Golden Eagle Battalion (GEB) which consists of 5 schools: Marquette University (Milwaukee, WI) which hosts the GEB, UW-Milwaukee (Milwaukee, WI), UW-Parkside (Kenosha, WI), Milwaukee School of Engineering (MSOE) (Milwaukee, WI), and Concordia University (Mequon, WI).

Procedures: Data collection was scheduled for two-hour sessions across four days which allowed for five flights of cadets (25 cadets total) to get through the protocol. Cadets performed a short warmup then were provided with questionnaires (demographics, previous sport participation since the age of five, and previous military experience) and the data collection sheet on a clipboard. Cadets rotated between five stations which included 1) check in/out & questionnaires 2) standing long jump (distance), 3) ball throw (velocity) and ball kick (velocity), 4) maximal vertical jump (height), and 5) Y-Balance. Station 1 involved describing the study, collecting written consent, providing participant IDs, putting cadets through the warm-up, providing all questionnaires and data collection sheets, and checking out cadets at the end of the collections. Station 2 involved cadets performing a standing long jump for maximal distance. Station 3 involved cadets throwing a tennis ball for maximal velocity at a target on a net followed by kicking an eight-inch diameter playground ball for maximal velocity. Station 4 involved cadets performing a maximal vertical jump in which 2-Dimensional (2D) video and accelerometer data were collected. Station 5 involved cadets performing the modified Y-balance which involved only completing the anterior reach portion of the protocol. The ACFT was conducted over a two-day period involving six events (maximal dead lift, standing power throw, hand release pushup, sprint drag carry, plank, and 2-mile run). ACFT data were collected by Army leaders as per standard protocol. The cadre provided height, weight, and the sex and age adjusted ACFT total and individual event scores to the research team in an excel file.

Main Outcome Measures: FMC composite score was calculated by summing the standardized best attempts of the four tasks in the FMC test battery (long jump distance, ball throw and kick velocity, and vertical jump height). Previous sport participation was collected with a self-report questionnaire and was separated into total number of years participated in sport and total number of sports participated in since the age of five. Reactive strength index (RSI) was calculated by dividing maximal jump height by time to takeoff for the vertical jump task. Dynamic balance was measured using the modified Y-balance utilizing only the anterior reach portion and the right/Left difference (R/L Diff) was used for analyses. ACFT individual event scores and total score were provided by the cadre. 2D sagittal plane angles of the trunk, hip, and knee were identified by importing 2D video into the Dartfish program. Pelvic and tibial acceleration was collected with MyoMotion IMUs to identify jump phases and to collect peak landing acceleration that was then used to calculate peak landing force in N.

Results: When added into the model with sex, RSI explained a significant amount of the variance in FMC composite score (change in R2=.341; p<.001) whereas dynamic balance did not (change in R2=.004; p=.382). Previous sport participation did not moderate any of the relationships between the fitness factors and FMC, but previous sport performance did have a non-linear relationship with FMC composite score. Five of the six events had significant correlational relationships with FMC however, SDC was the only event that was included in the model with sex and explained a significant amount of the variance in FMC score (change in R2 = .210, p < .001). ACFT total score was also a significant predictor of FMC composite score when entered the model with sex, explaining a significant amount of the variance in FMC composite score (change in R2 = .156, p <.001). Significant correlational relationships were found with all the biomechanical variables however knee flexion angle was the only biomechanical variable included in the final model with sex and accounted for a significant amount of variance in FMC score (change in R2 = .082, p < .001).

Conclusions: This study identified relationships among physical and neuromuscular fitness factors, sport participation, and FMC which prior to this study were speculative in nature. This study confirmed the relationship between FMC and ACFT total score following the revisions to the ACFT scoring protocol and found significant positive relationships among FMC and the individual ACFT tasks which had never been investigated before. The results of this study provide valuable support for the initial phases of research investigating the relationship between FMC and ACFT in ROTC cadets. The solidification of the relationship between FMC and ACFT supports the future utilization of the easily assessed FMC as a mechanism to understand how a cadet may perform on the ACFT. Finally, this study investigated how biomechanics were related to FMC which had never been directly compared. These results open avenues for exploration into FMC and its direct relationship with injurious biomechanics. Since FMC is often described as one’s ability to move their body through space safely and effectively, there are opportunities to investigate what that truly means within the ROTC population.

Download

Included in

Kinesiology Commons

Share

COinS