DECELERATIONS OF PARACHUTE OPENING SHOCK-AN EMPIRICAL STUDY IN SKYDIVERS

METHODS: In this empirical study, 20 experienced skydivers made two consecutive skydives each using their regular ram-air parachutes. Decelerations were recorded with two tri-axial accelerometers placed on the skydiver neck (acc-neck) and on the skydiving equipment rig (acc-rig). Magnitudes (G) and onset rates (Gs-1) of deceleration were analyzed separately for initial POS, i.e. a short (about 0.5 s) temporal window covering the first sudden rise of deceleration, and the following part of POS. RESULTS: Mean (standard deviation) of deceleration magnitudes for acc-neck vs. acc-rig during initial POS were 2.5 (0.4) G vs. 4.3 (0.9) G, compared to following POS values 3.8 (0.8) G vs. 4.8 (0.7) G. Max onset rates of deceleration were 29.7 (9.2) Gs-1 vs. 76.0 (13.0) Gs-1 during initial POS, compared to following POS values of 15.2 (5.4) Gs-1 vs. 32.2 (8.2) Gs-1. Mean average onset rates of deceleration during initial POS showed 5.9 (2.1 ) Gs-1 for acc-neck and 17.4 (4.1) Gs-1 for acc-rig. Significant differences were found for all variables between and within sensors for initial and following POS (p