Evaluating plasma lactate running speed derived parameters for predicting maximal lactate steady state in teaching horses.
Authors: Littiere T O, Costa G B, Sales N A A, Carvalho J R G, Rodriguez I D M, Ramos G V, Ferraz G C
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Determining the intensity at which horses can sustain aerobic work without accumulating blood lactate is critical for conditioning programmes, yet the field lacks consensus on which field-derived threshold best predicts this true maximal lactate steady state (MLSS). Littiere and colleagues compared four lactate-based parameters—V2 (2 mM lactate threshold), V4 (4 mM threshold), visual lactate threshold (VLTV), and a mathematically-derived bifurcated threshold (VLTBI)—against the MLSS obtained through repeated constant-intensity exercise bouts in ten teaching horses, using mean difference analysis and regression modelling to assess agreement between methods. The V4 threshold substantially overestimated sustainable intensity (2.12 ± 0.59 m/s higher than VMLSS), with horses reaching true MLSS at only 1.50 ± 0.37 mM lactate, making it unreliable for this population; conversely, V2, VLTV, and VLTBI all demonstrated acceptable agreement with measured MLSS. For practitioners designing training protocols, this research suggests abandoning the 4 mM fixed threshold as a universal marker and instead using either the 2 mM point, visual inflection analysis, or mathematical regression modelling—though further work establishing which approach best translates across different horse types and exercise modalities would strengthen field application.
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Practical Takeaways
- •The commonly used V4 (4 mM lactate) threshold significantly overestimates safe training intensity in horses and should not be relied upon for establishing MLSS without validation
- •Visual lactate threshold assessment or V2 method may provide more practical field-based alternatives for determining appropriate steady-state training intensities in teaching horses
- •When establishing training programs, consider using V2 or visual threshold methods rather than V4 to avoid overtraining and maximize aerobic conditioning
Key Findings
- •Mean plasma lactate concentration at MLSS was 1.50 ± 0.37 mM in teaching horses
- •V4 threshold was 2.12 ± 0.59 m/s higher than VMLSS and unsuitable for predicting MLSS
- •V2, VLTV (visual lactate threshold), and VLTBI showed lower mean bias compared to VMLSS
- •V2 and visual lactate threshold methods may be more accurate for predicting maximal lactate steady state than the traditional V4 method