Answer:
The correct answer is - overload.
Explanation:
The overload principle is the principle that states that producing the result continuously, exercise should be more challenging over the time period of any exercise program.
Lifting heavyweights in the strength training programs, muscles become sore due to challenging weight lifting by adding heavyweights in bars. Anthony is working on his strength training that is based on the overload principle by pushing himself.
Thus, the correct answer is - overload.