The Method but Not the Protocol Affects Lactate-Threshold Determination in Competitive Swimmers.

Area of Science:

• Exercise Physiology
• Sports Science
• Swimming Performance Analysis

Background:

• Accurate determination of lactate threshold (LT) is crucial for optimizing training in competitive swimming.
• Existing incremental protocols for assessing LT present variability in results.
• Validation against maximal lactate steady state (MLSS) is essential for reliable LT assessment.

Purpose of the Study:

• To validate speed at lactate threshold (sLT) and associated physiological variables (blood lactate, oxygen uptake, heart rate) using two incremental swimming protocols.
• To compare the validity of these protocols against maximal lactate steady state (MLSS).

Main Methods:

• Ten competitive swimmers underwent two 7x200m front-crawl incremental step tests with different rest intervals (30-second vs. 5-minute cycles).
• Five methods (2-line intersection, Dmax, modified Dmax, visual inspection, regression lines) were used to calculate sLT and physiological parameters.
• Swimmers also performed continuous 30-minute efforts to establish sMLSS and corresponding physiological measures.

Main Results:

• Both incremental protocols yielded comparable sLT and physiological variables, showing good agreement with MLSS.
• The modified Dmax method, particularly with short rests, showed a tendency to overestimate sLT compared to sMLSS.
• No significant differences were found between calculated LT variables (except modified Dmax sLT) and MLSS values across protocols.

Conclusions:

• Both short-rest and long-rest incremental protocols are valid for determining sLT and related physiological parameters in swimmers.
• The modified Dmax method should be used with caution as it may overestimate sLT.
• These findings support the use of validated incremental protocols for effective swimming training prescription.