A low-volume strength or power session within 48 hours can sharpen jumps and sprints in power athletes, but small endurance studies show no benefit and nothing tests long-course triathlon
Interpretation
Power and team-sport studies show improvements, e.g. jump height +5.1% at 24 h in 17 male athletes (Tsoukos 2018) and better afternoon sprint, jump and strength after morning lifting in 18 rugby players (Cook 2014), though reviews describe the evidence as limited and inconsistent (Harrison 2019, Holmberg 2023). In endurance athletes, heavy priming 5 h before a 3-minute ski test in 8 national-level men gave no significant benefit and caused low-frequency fatigue (Rud 2021), and a session 16 h before an 800 m in 11 runners changed nothing (Ihamäki 2023, unpublished thesis). Heavy sessions can impair endurance for hours to days (Doma 2017). No study tests any triathlon distance.
Practical implication
Don't add a new or heavy gym session the day before a long-course race. A short, familiar, lighter session early in race week fits normal taper practice; anyone who wants to try priming should test it before training or a minor race. Evidence is from young, mostly male power athletes and short endurance events.
Sources
8 sources, independently verified.
Brief review: low-volume resistance priming within 48 h of competition has improved various neuromuscular measures at times between 1 and 48 h, after heavy (85% 1RM or more) or lower-load ballistic exercise; evidence limited and sport-specific application unclear.
51% prescribed priming; 59% of those within 8 h of competition; about 3 sets (2.8 ± 0.9) of about 4 reps (3.8 ± 1.3); unloaded jumps (87%), loaded jumps (60%) and bench press (56%) most common; loads from bodyweight to 85% 1RM or more. Widespread use despite limited evidence.
Review: some priming studies report improved neuromuscular performance within 48 h, others no change or decreases; inconsistency attributed mainly to differing load, volume, timing and athlete characteristics.
A morning 3RM bench press and squat session improved afternoon (about 6 h later) countermovement jump power, 40 m sprint time and 3RM bench and squat versus rest or morning sprints; morning sprints improved 40 m time vs rest. Salivary testosterone did not fall am to pm after weights (-1.2 vs -10.9 pg/ml control).
5 x 4 jump squats at 40% 1RM improved countermovement jump by 5.1% at 24 h and 3.0% at 48 h, reactive strength index by 10.7% at 24 h, and rate of force development by 9.7-18.3% at 24 h; no changes with rest.
3 x 3 at about 85-90% 1RM (squat, sitting pullover) 5 h before testing did not improve double-poling time to exhaustion (~3 min; +3.6%, P = .29), 30 m sprints, jump or oxygen cost; low-frequency fatigue (-12%, P = .01) appeared only after priming. Authors suggest the session may have been too strenuous.
A priming session (leg press, isometric calf press, countermovement and drop jumps) at 4-6 pm, about 16 h before a morning 800 m, did not change 800 m time or pacing or improve jumps versus a non-priming session; more soreness after priming was linked to less benefit. Unpublished master's thesis, not peer reviewed.
Review of studies measuring endurance performance after single resistance sessions: residual fatigue can impair a subsequent endurance session for several hours to several days if recovery is inadequate, via altered neural recruitment, reduced movement efficiency, muscle soreness and lower glycogen. Recommends adjusting session order, recovery between modes and intensity. Narrative synthesis, not a meta-analysis.