The answer is force because Force is needed to change the direction of a moving mass.
Finding out if an exercise is safe needs to determine the fitness level of the exercise and how much it takes to achieve the result of the exercise. The person performing the exercise needs to know their endurance level and if they are able to perform the exercise without injury or illness.
It depends how long you do it because if you were to doing plank, it can be a choice for you to know when to stop.
Many prostate cancers that initially respond to hormone therapy with LHRH agonists, LHRH antagonists, or orchiectomy eventually stop responding to this treatment. ... Castration-resistant prostate cancersneed much lower levels of androgen to grow than androgen-sensitive cancers.