Dissociation between VO2max and ventilatory threshold responses to endurance training

Area of Science:

• Exercise Physiology
• Cardiovascular Adaptation
• Metabolic Response

Background:

• Endurance training elicits significant physiological adaptations.
• The ventilatory gas exchange threshold (Tvent) is a key indicator of exercise intensity.
• The temporal relationship between Tvent changes and other training adaptations is not fully understood.

Purpose of the Study:

• To investigate if the ventilatory gas exchange threshold (Tvent) significantly changes within the initial 1-3 weeks of endurance training.
• To compare the time course of Tvent adaptation with changes in VO2max, blood lactate levels, and heart rate.

Main Methods:

• Six male participants completed 3 weeks of cycle ergometer training (6 days/week, 30 min/session) at 70% of pretraining VO2max.
• VO2max, Tvent, and maximal/submaximal heart rates were assessed weekly.
• Blood lactate concentrations were measured during submaximal exercise sessions weekly.

Main Results:

• Tvent showed no significant change over the 3 weeks of training.
• VO2max increased significantly after 2 weeks.
• Blood lactate levels decreased significantly by week 2, and heart rates decreased significantly after 1 week.

Conclusions:

• Adaptations in the ventilatory gas exchange threshold (Tvent) occur later than improvements in VO2max, blood lactate clearance, and heart rate response during early endurance training.
• Tvent may not be the most sensitive early indicator of endurance training adaptation.