Background: Blood lactate kinetics provides insights into glycolytic contribution and recovery dynamics following high-intensity exercise. Although blood lactate responses following swimming performances have been previously reported, no study has examined blood lactate kinetics using a bi-exponential modelling approach or its relationship with stroke parameters during a 200-m freestyle event. Aim: To investigate the relationship between blood lactate kinetics and stroke parameters during a 200-m freestyle performance. Methods: Eleven trained male swimmers (21 ± 11 years) competing in state and national competitions performed a 200-m freestyle after a standardized warm-up. Blood samples were collected at rest, immediately before exercise, and during passive recovery at 1-min intervals up to 10 min, 2-min intervals up to 20 min, and 5-min intervals up to 60 min post-exercise. Lactate kinetics were modeled using a bi-exponential approach, yielding parameters for lactate appearance (K1), disappearance (K2), amplitude, peak concentration (Peak), and time to peak (tPeak). Stroke rate (SR) was determined from video analysis over a central 10-m section of each 25-m lap, and stroke length (SL) was calculated from swimming velocity and SR. Pearson correlations examined relationships between variables. Results: Mean 200-m time was 136.3±8.5 s. K1 was 0.407±0.188 min*¹, K2 was 0.042±0.006 min*¹, amplitude was 9.74±7.0 mmol·L*¹, Peak was 11.39±2.07 mmol·L*¹, and tPeak was 5.06±1.57 min, with high model fit (R²=0.992±0.006). No significant correlations were observed between performance time and lactate kinetics parameters. K1 was significantly correlated with SR at 25-m (r=0.67; p=0.02) and across the first 50-m (r=0.61; p=0.04). No other significant relationships were found between SR and lactate kinetics variables, and no correlations were observed between SL and any lactate kinetics parameter. Conclusions: Blood lactate kinetics parameters were not directly associated with 200-m performance but showed associations with early-race stroke rate. Further studies with larger samples are required to clarify their significance.
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