Morning priming exercises for explosive performance: time course effects of two-way ballistic and strength-based protocols

To examine the effects of low- and high-intensity two-way ballistic (TWB) priming exercise versus high-intensity traditional strength exercise (TSE) on explosive performance at 6 h and 24 h post-intervention. Twenty-eight well-trained male athletes completed four randomized morning sessions (08:00–11:00) in separate weeks: 30% 1RM TWB, 80% 1RM TWB, 80% 1RM TSE, and control. Each priming protocol comprised three sets of six repetitions with 4-min rest intervals. Explosive performance was assessed via countermovement jump (CMJ), five consecutive CMJs, and standing broad jump, measured pre-intervention, and at 6 h and 24 h post. After 6 h, all exercise conditions (excluding control) significantly improved CMJ height (30% 1RM TWB: 6.4 ± 5.0%, d = 1.31; 80% 1RM TWB: 7.4 ± 3.1%, d = 2.49; 80% 1RM TSE: 3.5 ± 4.2%, d = 0.83; all p < 0.01) and relative peak power (3.5 ± 1.8%, d = 1.87; 4.8 ± 1.8%, d = 2.83; 3.2 ± 2.1%, d = 1.53; all p < 0.01). Across conditions, average height across consecutive CMJs increased, with improvements of 6.7 ± 3.5% (d = 1.96), 7.6 ± 6.6% (d = 1.18), and 4.2 ± 2.7% (d = 1.53) for 30% 1RM TWB, 80% 1RM TWB, and 80% 1RM TSE, respectively (all p < 0.01). Similar patterns were observed for reactive strength index-modified (12.4 ± 12.1%, d = 0.95; 9.4 ± 11.7%, d = 0.79; 9.4 ± 14.1%, d = 0.71; all p < 0.01), and standing broad jump distance (1.9 ± 1.2%, d = 1.52; 2.4 ± 1.6%, d = 1.52; 1.1 ± 1.5%, d = 0.72; all p < 0.01). At 24 h, performance gains were largely diminished, with the 30% 1RM TWB condition returning to baseline (all p > 0.05). Both high-intensity protocols (TWB and TSE) maintained improvements, with the TWB protocol yielding the most consistent benefits, particularly in CMJ and CCMJ measures. Morning TWB priming at both low and high intensities enhances explosive performance within 6 h, making it a viable delayed potentiation strategy for sports with afternoon or evening competition. High-intensity TWB sustains benefits up to 24 h, indicating greater suitability for high-intensity or competitive settings requiring prolonged performance readiness.