Jump Squat Momentum: An Alternative Method to Prescribe Jump Squat Loads for Elite Rugby Union Players.

Loturco, I, Zabaloy, S, Bishop, C, Mercer, VP, Moura, TBMA, Ramos, MS, Freitas, TT, and Pereira, LA. Jump squat momentum: An alternative method to prescribe jump squat loads for elite rugby union players. J Strength Cond Res XX(X): 000-000, 2025-Rugby union is a team-sport in which collisions and impact forces play a decisive role. In this regard, momentum-based measurements (the product of mass and velocity of a body in a given movement) are frequently used by practitioners. Generally, sprint momentum (SM; the product of sprinting speed and athlete's body mass) is the most commonly considered momentum-based measure by coaches and sport scientists, either to differentiate playing positions or to examine player performance. However, recently, jump squat momentum (JSM) has been suggested as a complementary momentum-based measure because of its strong relationship with SM. In this study, we compared the body mass; half-squat 1 repetition maximum (HS 1RM), in both absolute and relative terms (i.e., relative strength [RS]); sprinting speed and momentum; and JSM of 21 rugby backs and forwards using an independent t test. As expected, forwards are significantly heavier and stronger and exhibit higher SM and JSM than backs (p ≤ 0.02). By contrast, backs are faster in linear sprints over both 10- and 30-m (p < 0.001) and exhibit higher values of RS (p < 0.05). Furthermore, irrespective of the playing position, RS was significantly different between the "low" and "high" RS groups (p < 0.001). Despite these marked differences, all players achieved their greatest magnitudes of JSM at an average of 40% HS 1RM. Strength and conditioning coaches interested in increasing JSM and its related metrics (e.g., SM) in rugby players could use this specific loading range to prescribe JS loads during their strength-power training sessions.