Intra- and Inter-Day Reliability of Inertial Loads with Cluster Sets When Performed during a Quarter Squat on a...

Area of Science:

• Sports Science
• Biomechanics
• Exercise Physiology

Background:

• Flywheel training offers variable resistance, enhancing power development.
• Cluster set protocols can optimize training volume and recovery.
• Attentional focus (internal vs. external) influences motor skill acquisition and performance.

Purpose of the Study:

• To assess the reliability of flywheel quarter-squat mean concentric (CON) and eccentric (ECC) power using cluster sets.
• To investigate the acute effects of internal and external attentional focus on mean power during this exercise.

Main Methods:

• Twelve male collegiate field sport athletes performed flywheel quarter-squats with cluster sets across four sessions.
• Four inertial loads (0.025–0.100 kg·m²) and a specific repetition scheme (4 × 5 + 5 + 5) were used.
• Mean power (MP), CON power, ECC power, and ECC overload were measured under internal and external attentional focus conditions.

Main Results:

• The external focus group demonstrated rapid familiarization (ES = 0.03–0.15) with low performance variability (CV% = 3.39–9.22).
• The internal focus group exhibited significant differences in MP output between sessions 2 and 3 (ES = 0.59–1.25).
• The cluster set approach proved reliable for maintaining MP output throughout repetitions.

Conclusions:

• The flywheel quarter-squat with a cluster set approach is a reliable training method.
• External attentional focus facilitates quicker adaptation and more consistent performance compared to internal focus in this exercise.