Cardiorespiratory Responses to Flywheel-Based Inertial Training Squats With Varying Moments of Inertia

Area of Science:

• Exercise Physiology
• Sports Science
• Biomechanics

Background:

• Flywheel-based inertial training (FIT) is recognized for muscle hypertrophy benefits.
• The application of FIT for aerobic exercise and its cardiorespiratory effects are largely unexplored.
• Understanding acute responses is crucial for developing novel training strategies.

Purpose of the Study:

• To investigate the cardiorespiratory responses to acute flywheel-based inertial training (FIT) squats.
• To examine the effects of varying moments of inertia (MOI) on physiological measures during FIT.
• To compare responses between males and females during FIT.

Main Methods:

• Twenty healthy, physically active participants (10 male, 10 female) completed maximal graded exercise tests.
• Participants performed quarter squats at 50 squats·min⁻¹ until volitional fatigue, with increasing MOI (0.005 kg·m² increments up to 0.020 kg·m²).
• Continuous monitoring of heart rate (HR) and gas exchange (V̇o₂, RER) with data averaged over the final 60 seconds of each stage.

Main Results:

• Increasing MOI significantly elevated HR, V̇o₂, and Respiratory Exchange Ratio (RER).
• Men exhibited higher V̇o₂ compared to women, with similar relative peak oxygen consumption (%V̇o₂ peak).
• A significant sex interaction showed lower RER in women at higher MOI; final stage RER approached 0.95-1.00.

Conclusions:

• Acute FIT quarter squats induce moderate HR and V̇o₂ responses.
• Near-maximal RER suggests a potent metabolic training stimulus that may exceed the lactate threshold.
• The sustainability and long-term physiological and performance effects of this training modality require further investigation.