Final answer:
Tightness in the gastrocnemius (calf muscle) and the gluteus medius (hip muscle) can lead to compensatory pronation or external rotation during a single leg squat. The correct answer is option c).
Step-by-step explanation:
When analyzing which muscles could be tight during a single leg squat with pronation or external rotation, it is essential to understand the muscle groups and their functions. Pronation and external rotation during a squat typically indicate compensation for weaknesses or tightness in certain muscles.
The main muscles affected would likely include the gastrocnemius (calf muscle), which is involved in plantar flexion of the foot and can affect pronation. Pronation can also be influenced by tightness in the gluteus medius (hip muscle), which is responsible for stabilizing the pelvis and preventing hip adduction and internal rotation when standing on one leg.
Although the hamstrings (back thigh muscles) and quadriceps (front thigh muscles) work together as opposing pairs for knee movement, they usually do not directly contribute to excessive pronation or external rotation of the foot. However, imbalances between these groups can impact overall leg alignment and mechanics.