Complex sentence: While the older and heavier Kay is physically stronger and has considerable endurance for her age, she proves to be no match for Laurie's stuntwoman training, who proceeds to try and choke Kay to death.
Split into simpler sentences: While the older and heavier Kay is physically stronger and has considerable endurance for her age, she proves to be no match for Laurie's stuntwoman training. Laurie quickly gains the upper hand and proceeds to try and choke Kay to death.