CONTINUOUS EKG RECORDING DURING FREE-FALL PARACHUTING
ARMY AEROMEDICAL RESEARCH UNIT FORT RUCKER AL
Pagination or Media Count:
An attempt was made to determine heart rate and rhythm of experienced parachutists during free-fall and during the periods immediately before and after the jumps. Continuous EKG recordings were made of 29 experienced parachutists while each participated in free-fall parachuting exercises. A total of 98 individual exits from aircraft in flight were recorded. Mean R-R interval was 0.403 seconds just prior to exit from the aircraft, 0.363 seconds during free-fall, 0.336 seconds immediately after parachute opening, 0.369 at landing, and 0.465 5 minutes after landing. Although there was variation in the R-R interval among individuals, the progressive decrease of R-R interval throughout the exit and free-fall with a nadir at parachute opening, was the common thing. There is marked individual difference in the duration of tachycardia before and after jumps. Over the entire group, mean duration per subject was 19.4 minutes of tachycardia prior to exit, and 30.4 minutes of tachycardia after parachute opening. In the individuals who made at least 2 jumps on any one day, the R-R interval measured on a single individual on the first and second jumps were remarkably similar, and within the group not statistically different. A correlation matrix was computed to show relationships between various parameters studied. The correlation between R-R interval and total number of jumps was opposite in direction to that which was expected, and nearly attained values that were statistically significant.
- Stress Physiology