Very little physical strength is required. There is less mainsheet to pull in when the jibe is complete. Student jibes several times in succession, using ladmarks selected by instrctor for course on each tack. Explain reversal of steering force during jibe, importance of being able to control the boat immediately after the jibe. If wind is light to medium, practice jibing with the mainsheet all the way in.
Instructor holds mainsheet, student jibes back and forth using only tiller, without changing sides.
Whatever is happening, always have control of the boat's direction and rate of turn. Never let go of the tiller in a crises. This alone is often enough to prevent a capsize. When jibing, it's critical to switch sides before the boom swings across, if at all possible. Even if the mainsheet is wrapped around your neck, this is priority three after steering and weight.