Which of the following represents common injuries related to fitness training?

The selection of shoulders, low back, and knees as common injuries related to fitness training is well-supported by research and clinical observations. These areas of the body are frequently subjected to overuse, strain, and impact during various forms of exercise.

The shoulders, being involved in a wide range of movements and exercises, can experience injuries such as rotator cuff tears or shoulder impingement, especially in athletes who engage in weightlifting or overhead activities. The low back is another critical area that can suffer from conditions like strains and sprains due to improper lifting techniques or overexertion during workouts. Injuries to the knees are also prevalent, particularly since they are key weight-bearing joints that endure significant stress during activities such as running, jumping, or squatting. Conditions like patellar tendinitis and ligament injuries (like ACL tears) are common among individuals who engage in fitness training.

While the other options mention various body parts that might experience injuries, they are not as typically associated with the most common injuries seen in fitness training as the shoulders, low back, and knees are. Thus, those areas stand out as primary candidates for injury considerations in the context of fitness.