You might have tight muscles in the lower back or outside thigh, poor quadricep strength, flat feet or knock - knees. (womenshealthandfitness.com.au)
In a nutshell, the anatomic traits that are associated with a more upright squatting posture include: greater heel elevation, greater ankle dorsiflexion mobility, shorter femur length, longer torso length, wider stance width, more abduction, a higher bar position on the back, greater quadriceps strength and increased intent to target the knee extensors. (fitnessandpower.com)
Compared to baseline, VO2max and peak quadriceps strength declined on the 1.2 g / kg protein dose, whereas both of these functions were preserved at the 1.5 g / kg level. (blog.virtahealth.com)