Maximal Lactate Steady State's Dependence on Cycling Cadence

Area of Science:

• Exercise Physiology
• Sports Science
• Biochemistry

Background:

• The maximal lactate steady state (MLSS) is a key indicator of endurance capacity, representing the highest blood lactate concentration (BLC) sustainable without continuous accumulation.
• Previous research indicated no difference in MLSS between 100 and 50 rpm, but recent findings suggest higher BLC at 100 rpm during incremental exercise.
• Cycling cadence may influence metabolic responses, including lactate accumulation and substrate utilization.

Purpose of the Study:

• To investigate the effect of different cycling cadences (105 rpm vs. 60 rpm) on the maximal lactate steady state (MLSS).
• To test the hypothesis that MLSS is higher at 105 rpm compared to 60 rpm, while the intensity at MLSS (I_MLSS) remains unchanged.
• To confirm these findings using both between-subjects and within-subject study designs.

Main Methods:

• Two studies were conducted: Study I used a between-subjects design (n=16 per group) comparing MLSS and I_MLSS at 105 rpm and 60 rpm.
• Study II employed a within-subject design (n=12) to confirm the findings on MLSS and I_MLSS at the same cadences.
• Measurements included blood lactate concentration (BLC) and respiratory exchange ratio (RER) during prolonged constant workload tests.

Main Results:

• Study I revealed a significantly higher MLSS at 105 rpm (5.4 ± 1.0 mmol/L) compared to 60 rpm (4.3 ± 0.7 mmol/L), with no significant difference in I_MLSS (71.8% ± 5.9% vs. 68.7% ± 5.3%).
• Study II corroborated these results, showing a higher MLSS at 105 rpm (4.5 ± 1.0 mmol/L) versus 60 rpm (3.4 ± 0.8 mmol/L), and confirmed no difference in I_MLSS (63.5% ± 6.3% vs. 65.0% ± 6.8%).
• At MLSS, the respiratory exchange ratio (RER) remained close to 1 across both cadences.

Conclusions:

• Higher cycling cadences (105 rpm) lead to a higher MLSS compared to lower cadences (60 rpm), supporting the hypothesis.
• The intensity at MLSS (I_MLSS) is independent of cycling cadence within the tested range.
• These findings suggest that higher cadences may promote carbohydrate preservation during prolonged, low-intensity endurance training at equivalent blood lactate levels.