(22) LEG TUCK OR PLANK? CRITICAL DECISIONS TO OPTIMIZE OCCUPATIONAL TEST ASSESSMENT IN ARMY PERSONNEL

The U.S. Army recently implemented a new occupational fitness test, the Army Combat Fitness Test (ACFT). The original ACFT was met with widespread controversy due to the inclusion of the leg tuck (LTK). The LTK was intended as a proxy measure of a Soldier’s ability to climb a rope or scale an obstacle (i.e., a testable measure of upper body pulling and core strength); however, a disproportionate number of female soldiers had suboptimal LTK performance. In 2022, the LTK was replaced by the plank (PLK). While the PLK would test core endurance, the relationship to the pulling strength is tenuous at best. It is unclear if the transition from the LTK to the PLK was due to a decision to emphasize core strength and endurance, implement a more equitable event based on the notable performance differences between males and females, or provide an event that closely aligns with combat or soldiering tasks.

Purpose: To determine the relationship between the LTK and PLK with pullups (PUP) and handgrip strength (HGS) between male and female Soldiers.

Methods: Forty-one (23 males, 18 females; age: 30.1 ± 6.5 years, height: 171.1 ± 9.2 cm, weight: 76.1 ± 16.1 kg) Army personnel completed the study. Each participant was required to complete visit 1, a maximum effort HGS and PLK assessment, and visit 2, a randomized maximum effort PUP and LTK assessment. Descriptive statistics were calculated for all variables (mean ± SD). Independent samples t-tests calculated between sex differences. Overall correlations were reported with and without sex as a covariate. Correlations were interpreted according to the thresholds developed by Cohen. A stepwise linear regression, controlling for sex, determined which variables predicted LTK and PLK performance. Significance was set a priori as p < .05.

Results: Male soldiers had higher HGS (mean difference [MD] = 54.7 kg, p < .001), longer PLK times (MD = 23.0 s, p = .024), more LTK (MD = 9.6 reps, p < .001) and PUP (MD = 8.1 reps, p < .001) repetitions compared to female soldiers. Leg tuck and PLK performance were strongly correlated (r = 0.53, p < .001). When controlling for sex, this effect was attenuated (r = 0.42), but remained significant (p = .007). With sex as a covariate, LTK was moderately and strongly correlated to HGS (r = 0.42, p = .008) and PUP (r = 0.82, p < .001), respectively. Based on the stepwise regression, 80.9% of the variance in LTK performance was explained by sex and PUP (p < .001). The addition of HGS did not change the model (F change p = .871). For the PLK, 12.3% of the variance in performance was explained by sex (p = .024); however, adding PUP and HGS did not significantly change the model.

Conclusions: Both LTK and PLK performance was influenced by sex; whereas, only the LTK was related to upper body pulling strength as measured by PUP. PRACTICAL APPLICATION: Since the Army accounts for sex differences on performance via differential scoring, ACFT events should be selected, primarily, on events that align most closely with soldiering and combat tasks.

Acknowledgements: None.