Final answer:
Jane's weight-training plan violates the principle of specificity in fitness training.
Step-by-step explanation:
The principle of fitness training that Jane's plan violates is the principle of specificity. This principle states that the training program should be specific to the goals and desired outcomes. In Jane's case, she wants to increase her cardiorespiratory endurance, but she is embarking on a weight-training program which primarily focuses on increasing muscle strength.
To improve cardiorespiratory endurance, Jane should engage in aerobic exercises such as cycling, walking, or running. These exercises increase the heart rate and improve the efficiency of the cardiovascular system, leading to enhanced endurance.
By solely focusing on weight training, Jane is not targeting the specific aspect of fitness she wants to improve, and therefore her plan violates the principle of specificity.