Analyzing the Training Load Demands, and Influence of Sex and Body Mass, on the Tactical Task of a Casualty Drag via Surface Electromyography Wearable Technology

This study measured the training load (TL) demands associated with a military-specific casualty drag measured via surface electromyography (sEMG) wearable technology, and the influence of sex and body mass on these measures. Thirty-six college-aged participants (males = 25; females = 11) performed two trials of a 123-kg (91-kg dummy with 32-kg load) backwards casualty drag over 15 m. Time was recorded to calculate drag velocity, with the fastest trial analyzed. Prior to testing, participants were fitted with compression garments embedded with sensors to measure the vastus lateralis and medialis (quadriceps; QUAD), biceps femoris (BF), and gluteus maximus (GM) of both legs. The sEMG signal for each muscle was measured as a percentage of maximal voluntary contraction to calculate TL. The variables included TL (total, QUAD, BF, GM), and between-muscle ratios. The sample was also ranked and median split via body mass into heavier and lighter groups. Independent samples t-tests calculated differences between drag velocity and TL for the sex and body mass groups. Pearson’s correlations calculated relationships between body mass and velocity with the TL variables (combined, males, females). Females and lighter participants experienced greater TL compared to males and heavier participants, respectively (p < 0.01). A slower drag velocity correlated with a greater total and QUAD TL for all participants, males, and females (p ≤ 0.03, r = -0.65--0.80). Performing a slower casualty drag will increase TL demands, predominantly via QUAD stress. Training staff should develop the muscles important for the drag, especially for females and lighter males.