A prospective evaluation of non-interval- and interval-based exercise training progressions in rodents

Area of Science:

• Exercise Physiology
• Animal Models
• Training Methodologies

Background:

• Establishing effective progressive overload is crucial for rodent exercise training studies.
• Understanding optimal training progressions is essential for consistent and reproducible research outcomes.

Purpose of the Study:

• To determine the daily rate of treadmill speed increase for non-interval training in rats.
• To compare the number of training days required to reach target intensities using non-interval versus interval training progressions.
• To establish methods for progressive overload in rodent exercise protocols.

Main Methods:

• Rats were assigned to mild, moderate, or heavy intensity non-interval training groups, or a heavy intensity interval training group.
• Non-interval training involved daily increases in treadmill speed; interval training involved daily increases in interval duration.
• Training occurred 5 days per week for 6 weeks, with treadmill speed and grade adjusted progressively.

Main Results:

• Treadmill speed increased by approximately 0.6-0.8 m·min(-1)·day(-1) across non-interval training groups.
• Rats reached target intensities after 0.4 days (mild), 17 days (moderate), and 23 days (heavy) of non-interval training.
• Interval training required significantly fewer days (11 days) to reach the heavy-intensity target.

Conclusions:

• Rodents tolerate a daily treadmill speed increase of ~0.7 m·min(-1)·day(-1) for progressive overload.
• Non-interval training allows continuous running at moderate to heavy intensities within 3-4 weeks.
• Interval training is a more time-efficient method for achieving high exercise intensities in rodents.