Does critical swimming velocity represent exercise intensity at maximal lactate steady state?

Area of Science:

• Sports Science
• Exercise Physiology
• Swimming Performance

Background:

• Critical swimming velocity (vcrit) is a key metric in competitive swimming.
• The relationship between vcrit and maximal lactate steady state (MLSS) intensity is not fully understood.
• Accurate determination of MLSS is crucial for optimizing training programs.

Purpose of the Study:

• To investigate if critical swimming velocity (vcrit) aligns with the exercise intensity at maximal lactate steady state (MLSS).
• To establish a simple method for calculating vcrit using two maximal effort swims.
• To validate the calculated vcrit against established measures of swimming performance and lactate response.

Main Methods:

• Eight swimmers performed maximal effort 200m and 400m swims to calculate vcrit as the slope of distance/time.
• Swimmers then completed a 1600m freestyle test at 98%, 100%, and 102% of their calculated vcrit.
• Blood lactate concentrations were measured throughout the MLSS test.

Main Results:

• The newly calculated vcrit showed significant correlations with swimming velocity at 4 mmol.l-1 blood lactate (r=0.914) and mean 400m freestyle velocity (r=0.977).
• At 100% vcrit, blood lactate reached a steady state of ~3.2 mmol.l-1.
• Lactate levels increased progressively at 102% vcrit, while decreasing at 98% vcrit, indicating 100% vcrit as the MLSS intensity.

Conclusions:

• Critical swimming velocity (vcrit), determined via two timed maximal swims, appears to correspond to the exercise intensity at maximal lactate steady state.
• This simplified vcrit calculation method offers a practical tool for assessing MLSS in swimmers.
• The findings support the use of vcrit for tailoring training intensities to optimize swimming performance and endurance.