Mullane, MD, Maloney, SJ, Chavda, S, Williams, S, and Turner, AN. Effects of concurrent activation potentiation on countermovement jump performance. J Strength Cond Res 29(12): 3311–3316, 2015—The purpose of this study was to assess the effects of concurrent activation potentiation (CAP) on countermovement jump (CMJ) performance. Twenty-four resistance-trained males (mean ± SD; age: 25 ± 4 years, body mass: 78.7 ± 10.3 kg) performed a CMJ on a force plate under 4 different conditions: (a) a control condition where the CMJ was performed with hands on hips and lips pursed, thus preventing jaw or fist contraction from occurring, (b) a jaw condition where the CMJ was performed with maximal contraction of the jaw, (c) a fist condition where the CMJ was performed with maximal contraction of the fists, and (d) a combined condition where the CMJ was performed with maximal contraction of both jaw and fists. Jump height (JH), peak force (PF), rate of force development (RFD), and time to peak force (TTPF) were calculated from the vertical force trace. There was no significant difference in PF (p = 0.88), TTPF (p = 0.96), JH (p = 0.45), or RFD (p = 0.06) between the 4 conditions. Effect size (ES) comparisons suggest a potential for CMJ with fist and jaw contraction (BOTH condition) to augment both PF (2.4%; ES: 0.62) and RFD (9.9%; ES: 0.94) over a normal CMJ (NORM condition). It is concluded that CAP by singular and combined contractions has no significant impact on CMJ performance; however, substantial interindividual variation in response to CAP was observed, and such techniques may therefore warrant consideration on an individual basis.