Repeated Sprint Performance and Inter-Limb Asymmetry in Elite Female Sprinters: A Study of Lactate Dynamics and Lower Limb Muscle Activity.

Repeated short maximal sprints induce high blood lactate concentrations and may influence neuromuscular coordination, but the relationship between lactate accumulation and inter-limb asymmetry in elite athletes remains unclear. This study sought to investigate how blood lactate dynamics during repeated sprint efforts relate to sprint performance and inter-limb muscle asymmetry in elite female sprinters. Eight elite women (21.3 ± 5.4 y; 54.2 ± 5.1 kg; 165.4 ± 4.3 cm) performed four sets of five all-out 50 m sprints (1 min rest between reps; 5 min between sets). Sprint times were electronically timed. Capillary lactate was measured at rest and 1 min/4 min post-set. Quadricep, hamstring, and gluteal asymmetry was assessed via textile electromyography. Nonparametric statistics (Spearman's ρ, Friedman test) were applied. From Set 1 to Set 4, sprint time fell from 7.25 ± 0.13 s to 7.07 ± 0.16 s ( = 0.044), 1 min lactate rose from 8.51 ± 2.65 to 15.60 ± 2.66 mmol/L ( < 0.001), and 4 min lactate from 7.16 ± 2.32 to 13.64 ± 2.76 mmol/L ( = 0.002). Muscle group asymmetries decreased ( < 0.01), with lactate at 1 min, correlating negatively with quadriceps (ρ = -0.59) and gluteal (ρ = -0.48) asymmetry. In elite female sprinters, progressive lactate accumulation during repeated 50 m bouts is linked to faster times and reduced muscle asymmetry, suggesting that lactate may enhance neuromuscular coordination under fatigue.