Plasma lactate concentrations for self-selected maximal effort lasting 1 h

Area of Science:

• Exercise Physiology
• Sports Science
• Biochemistry

Background:

• Understanding plasma lactate concentrations is crucial for assessing endurance performance in athletes.
• The commonly used OBLA (onset of blood lactate accumulation) threshold of 4 mmol x L(-1) is often cited but its applicability in maximal efforts needs further investigation.

Purpose of the Study:

• To determine plasma lactate concentrations in well-trained endurance cyclists and triathletes during a 1-hour maximal laboratory cycling trial.
• To investigate the relationship between plasma lactate levels and cycling performance (maximal distance cycled in 1 hour).

Main Methods:

• Eleven well-trained endurance cyclists or triathletes completed three 1-hour maximal distance cycling trials.
• Blood samples were collected every 10 minutes during the third trial (T) from a forearm vein.
• Plasma lactate concentrations ([La]) were analyzed using spectrophotometry.

Main Results:

• Subjects cycled an average of 40.8+/-2.2 km, at 83+/-4% of their predicted maximum heart rate (HRmax).
• Individual plasma lactate concentrations ([La]) varied significantly, with minimums ranging from 2.8 to 10.3 mmol x L(-1) and maximums from 5.8 to 13.6 mmol x L(-1).
• Average [La] from minutes 10 to 50 ranged from 5.0 to 12.3 mmol x L(-1) and did not correlate with the distance covered.

Conclusions:

• The 4 mmol x L(-1) threshold (OBLA) may underestimate lactate tolerance during 1-hour maximal endurance tests.
• Intersubject variability in plasma lactate concentration during such efforts does not correlate with performance outcomes.
• Individualized assessment of lactate response is important for understanding maximal endurance capacity.