RELATIONSHIP OF LEG STRENGTH AND POWER TO GROUND REACTION FORCES IN BOTH EXPERIENCED AND NOVICE LUMP TRAINED PERSONNEL

There were 14 male soldiers who participated in this study examining t he relationship of leg strength and power on landing performance. Subj ects were separated into two groups. The first group (E, n = 7) were p arachute training instructors and highly experienced in parachute jump ing. The second group oi subjects (N, n = 7) had no prior parachute tr aining experience and were considered novice jumpers. All subjects wer e tested for one-repetition maximum (1RM) squat strength and maximal j ump power. Ground reaction forces (GRF) and the time to peak force (TP F) at landing were measured from jumps at four different heights 195 c m, 120 cm, 135 cm, and 170 cm). All jumps were per formed from a custo mized jump platform onto a force plate. Results: No differences were s een between E and N in either 1RM squat strength or in MJP. In additio n. no differences were seen between the groups for time to peak force at any jump height. However, significantly greater GRF were observed i n E compared to N. Moderate to high correlations between maximal jump power and GRF (r values ranging from 0.62-0.93, were observed in E. Al though maximal jump power and the TPF was significantly correlated (r = -0.89) at only 120 cm for E, it was interesting to note that the cor relations between MJP and the time to peak force in E were all negativ e and that the correlations between these variables in N were all posi tive. Conclusion: These results suggest that experienced parachutists may use a different landing strategy than novice jumpers. This differe nce may be reflected by differences in GRF generated during impact and a more efficient utilization of muscle power during the impact phase oi the landing.