Jeffreys, MA, De Ste Croix, MBA, Lloyd, RS, Oliver, JL, and Hughes, JD. The effect of varying plyometric volume on stretch-shortening cycle capability in collegiate male rugby players. J Strength Cond Res 33(1): 139-145, 2019-The purpose of this study was to identify the effectiveness of low and high volume plyometric loads on developing stretch-shortening cycle capability in collegiate rugby players. A between-group repeated measures design was used. Thirty-six subjects (age 20.3 ± 1.6 years, mass 91.63 ± 10.36 kg, stature 182.03 ± 5.24 cm) were randomly assigned to one of 3 groups: a control group (CG), a low volume plyometric group (LPG), or a high volume plyometric group (HPG). Data were collected from a force plate, and measures of reactive strength index (RSI) and leg stiffness were calculated from jump height, contact time, and flight time. A significant between-group × time (F = 4.01, p ≤ 0.05) interaction effect for RSI was observed. Bonferroni post hoc analysis indicated that both the LPG training group (p = 0.002) and HPG training group (p = 0.009) were significantly higher than the control group. No significant interaction effect between time × group was observed for leg stiffness (F = 1.39, p = 0.25). This study has demonstrated that it is possible to improve reactive strength capabilities through the use of a low volume plyometric program. The low volume program elicited the same performance improvement in RSI as a high volume program while undertaking a lower dose. This suggests that strength and conditioning coaches may be able to benefit from the ability to develop more time-efficient and effective plyometric programs.