"Uchida, straighten up your waist a bit more!"
"Miyamoto, raise your sword higher, strike with force."
"Look at President Ayakoji, how standard his posture is. Just continue like that."
Teacher Yamazaki, who was coaching, was instructing everyone to practice swings with a heavier wooden sword.
The so-called swings refer to swinging the sword in empty air from top to bottom. While exerting force, one must keep the upper body still. It is the most basic exercise method aimed at increasing strength.
If one were to swing a bamboo sword in empty air, it wouldn't be very effective; however, using a heavier wooden sword for the swings would be quite painful.
Imagine holding a barbell with both hands, lifting it upwards repeatedly, forcefully swinging it downwards, all while maintaining a standard posture each time.