Background: Pacing behaviour in swimming is shaped by intrinsic factors — athlete age, experience, and evolving physical capacities — and extrinsic factors such as competitive environment, adversity, fatigue, and Olympic cycle demands (Menting et al., 2019). Menting et al. (2023) further showed that pacing development in adolescent freestyle swimmers is driven by age-related factors beyond race experience alone. Aim: To examine the longitudinal evolution of individual pacing strategy across international competitions for the 200-m freestyle in two elite swimmers with contrasting career profiles (junior and/or senior medalists). Methods: All 200-m freestyle long-course races (heats, semi-finals, finals) from major international competitions (Olympic Games, World Championships, Junior World Championships, 2011-2025) were collected for James Guy (JG; 913 FINA pts, n = 16, aged 17-29) and Cameron McEvoy (CM; 888 FINA pts, n = 8, aged 17-21). Pacing was quantified using the Pacing Index (PI = V*/V*), Fatigue Index (FI = (V_max * V_last)/V_max × 100), and velocity profiles normalized to mean race speed (%V*), following Abbiss and Laursen (2008). A positive profile reflects progressive speed decline; an even profile includes speed increase at the end. Results: CM showed the greatest improvement (* = 4.68%, 111.3 * 106.09 s), the highest PI (1.080 ± 0.007 m·s*¹), and the highest FI (11.07 ± 2.15%; range 9.12-14.4%); his three finals comprised one even (medal) and two positive. JG improved by 3.40% (108.84 * 105.14 s), with PI = 1.071 ± 0.007 m·s*¹ and FI = 9.34 ± 1.77% (range 6.04-11.87%); his five finals comprised three even (2 medals) and two positive, reflecting greater sensitivity to competitive environment and fatigue context. Conclusions: Despite distinct career trajectories, both swimmers adopted positive pacing in finals toward the end of their careers. JG displayed a more gradual speed decline, whereas CM showed a higher PI with faster deceleration over the final two laps. CM subsequently specialised in the 50/100 m, suggesting his front-loaded 200-m strategy may have anticipated this transition. Future work should integrate stroke-cycle parameters and physiological markers to disentangle the roles of age, experience, and competitive context on pacing evolution.
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