Projected kinematic variability during the barrier-step action in elite futsal goalkeepers: A low-cost video workflow case series

This field-based case series developed and applied a low-cost, high-speed two-dimensional video workflow to analyse the barrier-step action in elite futsal goalkeepers. Three male professional goalkeepers with international experience (age 28.3 ± 3.2 years; height 182.4 ± 4.1 cm; body mass 78.6 ± 5.3 kg) completed three valid dominant-side trials each in a standardised indoor task (nine trials). Video was recorded at 240 frames·s ⁻¹ and analysed frame by frame in Kinovea. The action was operationally segmented into initiation-propulsion, lateral transfer, and terminal support-stabilisation. Projected ankle, knee, hip, and shoulder angles were extracted at the end of initiation-propulsion and at first terminal-support foot contact. Temporal organisation was goalkeeper-specific, particularly during initiation-propulsion. Between-goalkeeper coefficients of variation, calculated from the three goalkeeper mean values, decreased from 36.1% to 4.1% for ankle angle, 40.1% to 3.2% for knee angle, and 15.2% to 4.6% for hip angle, whereas shoulder dispersion remained high. Within this case series, the workflow distinguished individual preparatory organisation from reduced lower-limb angular dispersion at the blocking instant. The findings support the feasibility of accessible video-based sports engineering workflows when operational definitions and interpretive limits are explicit.