Final answer:
Polynomial regression should be applied if a client is having trouble maintaining form during a tuck jump exercise.
Step-by-step explanation:
If a client is having trouble maintaining form during a tuck jump exercise, the type of regression that should be applied is Polynomial regression.
Polynomial regression is used when the relationship between the dependent variable and the independent variable is not linear. In this case, the form of the tuck jump exercise may not follow a simple linear relationship, and polynomial regression can capture more complex relationships.
For example, if the client's form deteriorates after a certain point in the exercise, polynomial regression can capture this non-linear relationship and provide insights on how to improve the form.