Which principle states that not everyone can train in the same manner?

The Principle of Individual Differences emphasizes that each individual possesses unique physiological and psychological characteristics that affect how they respond to training stimuli. This principle recognizes that factors such as age, gender, body composition, fitness levels, and even individual goals can significantly influence the effectiveness of a training program. Consequently, not everyone will achieve the same results from a given training regimen; some may excel while others may struggle.

Tailoring training programs to accommodate these individual differences can lead to better outcomes and increased adherence to the program. It underscores the importance of personalization in training, making it essential for coaches and trainers to assess and understand each athlete's specific needs and capabilities in order to optimize performance. This principle, in contrast to the other options, directly addresses the necessity of individualized approaches in physical conditioning.