Aerobic adaptations following two iso-effort training programs: an intense continuous and a high-intensity interval

Area of Science:

• Exercise Physiology
• Sports Science
• Cardiovascular Adaptations

Background:

• Training intensity and perceived exertion are key drivers of physiological adaptations and long-term training improvements.
• Understanding the comparative effects of different training modalities, such as continuous versus interval training, is crucial for optimizing exercise prescription.
• Previous research has explored various training protocols, but direct comparisons of iso-effort continuous and high-intensity interval training on aerobic capacity are less defined.

Purpose of the Study:

• To compare the aerobic adaptations resulting from two iso-effort training programs: intense continuous (CON) training and high-intensity interval (INT) training.
• To investigate the effects of these training programs on maximal oxygen uptake (VO2max), peak treadmill velocity (PTV), critical velocity (CV), and lactate threshold velocity (vLT).

Main Methods:

• Young adults were allocated to either a CON or INT group, undertaking 14 training sessions over six weeks.
• The INT group performed high-intensity running bouts at 90% of PTV, while the CON group ran at approximately 80% of PTV (below critical velocity).
• Both groups trained to achieve a Rating of Perceived Exertion (RPE) of 17 on the Borg scale, ensuring iso-effort (matched internal load).

Main Results:

• Both CON and INT training significantly improved VO2max, PTV, CV, and vLT (p < 0.05) without significant differences between the groups.
• Running economy remained unchanged in both training groups post-intervention.
• The CON group trained at a speed corresponding to approximately 80% of PTV, within the heavy-intensity domain.

Conclusions:

• Intense continuous training, when matched for perceived exertion and performed at high intensity, elicits comparable aerobic adaptations to high-intensity interval training.
• This suggests that continuous training at the upper limits of the heavy-intensity domain can be an effective strategy for improving aerobic capacity over a short-term period.
• Both training modalities are effective for enhancing key markers of aerobic fitness in young adults.