The aim of this study was to compare the effects of two different intensity distribution training programmes (polarized (POL) and threshold (THR)) on aerobic performance, strength and body composition variables in ultra-endurance runners. Twenty recreationally trained athletes were allocated to POL (n = 11; age: 40.6 ± 9.7 years; height: 175.4 ± 7 cm; weight: 73.5 ± 10.8 kg; fat mass 18.4 ± 6.0%; VO2max: 55.8 ± 4.9 ml/kg/min) or THR group (n = 9; age: 36.8 ± 9.2 years; height: 178.5 ± 4.2 cm; weight: 75.5 ± 10.4 kg; fat mass 14.9 ± 5.3%; VO2max: 57.1 ± 5.2 ml/kg/min) and performed the 12 weeks training programme. Both programmes had similar total time and load but a different intensity distribution (POL = 79.8 ± 2.1% in Zone 1; 3.9 ± 1.9% in Zone 2; 16.4 ± 1.5% in Zone 3; THR = 67.2 ± 4.6% in Zone 1; 33.8 ± 4.6% in Zone 2; 0% in Zone 3). Body composition, isokinetic strength and aerobic running performance were measured before and after each programme. Both groups decreased fat mass after training (POL= Δ-11.2%; p = .017; ES = 0.32; THR= Δ-18.8%; p < .01; ES = 0.48). Also, POL group improved running economy at 10 km/h (Δ-5.4%; p = 0.003; ES = 0.71) and 12 km/h (Δ-4.5%; p = .026; ES = 0.73) and running time to exhaustion (Δ2.4%; p = .011; ES = 0.33). No changes were observed in strength and no significant differences were observed between the group in any variable. Compared with THR distribution, 12 weeks of POL training efficiently improves aerobic performance in recreational ultra-endurance runners.
Keywords: Endurance; performance; training.