Effect of drop jump training frequency on reactive strength in rugby athletes

Abstract

Background Jumping is a commonly used training modality to improve athletic performance and neuromuscular capabilities. The capacity to rapidly absorb eccentric forces and rapidly produce a concentric force within a stretch-shortening cycle (SSC) is referred to as reactive strength (RS)¹. The drop jump (DJ) is assesses RS and has been used as a proxy for fast SSC (<250 ms)². The ability to utilise the fast SSC during running and jumping is an essential part of athletic preparation in rugby players³ . Methods 24 academy rugby athletes (97.3 ± 12.1 kg, relative 1RM back squat: 1.59 ± 0.24 kg/kg, 10 m sprint: 1.73 ± 0.09 s) performed an identical 6-week daily undulating periodized resistance training program but were randomly allocated to a high (3 sessions per week, [HF]) or low frequency (1 session per week, [LF]) DJ training group matched for RS. Results Both groups improved RS (Effect Size [ES ± 90% CL], LF: 0.55 ± 0.41 & HF: 0.70 ± 0.27, both p < 0.05), and relative 1RM in the back squat (LF: 0.39 ± 0.12 & HF 0.36 ± 0.27, both p < 0.05). There was a clear difference between the improvement in 5-0-5 agility times in favour of the HF group (ES: 0.28 ± 0.27, p < 0.08). Only the HF group demonstrated a significant improvement in countermovement jump performance (ES: 0.27 ±0.21, p<0.04). No between group differences were observed in 10 m sprint times or relative 1RM in the back squat. Discussion The higher frequency of DJ training improved agility and jumping ability in academy rugby athletes. To elicit positive changes in relevant functional measures requires a training commitment of at least three days per week. While RS and agility were related, there was no evidence of covariance over time.