Andrew C. Fry, Luke Bradford, Trent Herda, Joseph Weir FACSM, Michael Lane, Matthew Andre, Andrea Hudy, J. Deckert and J. Siedlik.Neuromechanics Laboratory and Kansas Athletics Inc., University of Kansas, Lawrence, KS
Analyses of barbell kinetics and kinematics have typically required the use of force plates, tether-based position transducers, or digitized video analysis. PURPOSE: To determine the validity of a 3-dimensional video markerless motion capture system for determining barbell kinetics and kinematics. METHODS: Two 3-D video cameras sampling at 30 Hz and mounted on the top of a power rack were interfaced with a self-contained computer and software system, and operated with a touch screen (EliteForm, Lincoln, NE). For laboratory comparison purposes, a ceiling–mounted linear position transducer (Unimeasure, Corvallis, OR) was attached via a tether to the barbell. Data from the position transducer was sampled at 1000 Hz using a BioPac data acquisition system (Goleta, CA). Velocity (m.s-1) and power (W) were derived using LabView software (National Instruments, Austin, TX). One weight-trained male subject (age = 25 yrs, hgt = 1.75 m, BW = 82.6 kg, 1 RM = 161.0 kg) performed the barbell bench press exercise for 10 sets x 1 repetition at 30, 40, 50, 60, 70 and 80% 1 RM loads using maximal acceleration during the concentric phase. Dependent variables included peak (PV) and X̅ velocity (MV) and peak (PP) and X̅ power (MP). Linear regressions between lab-derived and 3-D video-derived data provided correlation coefficients, and regression slopes (b). Bland-Altman plots were used to determine X̅ differences, from which effect sizes (Cohen’s D) and % error for the 3-D camera system was determined. RESULTS: Lab-derived mean values for all loads ranged as follows; MV = 0.36 – 1.00 m.s-1, PV = 0.47 – 1.60 m.s-1, MP = 460.9 – 621.6 W, and PP = 619.9 – 1055.6 W.
CONCLUSION: The 3-D video markerless motion capture system provided accurate and valid barbell velocity and power data for the bench press exercise.
Supported in part by Nebraska Global LLC
Fry, AC; Bradford, L; Herda, T; Weir, J FACSM; Lane, M; Andre, M; Hudy, A; and Siedlik, J
"VALIDATION OF A 3-DIMENSIONAL VIDEO MOTION CAPTURE SYSTEM FOR DETERMINING BARBELL POWER AND VELOCITY DURING THE BENCH PRESS,"
International Journal of Exercise Science: Conference Proceedings: Vol. 11
, Article 63.
Available at: http://digitalcommons.wku.edu/ijesab/vol11/iss1/63