Which describes concentric contraction during a squat ascent?

• A. The quadriceps and gluteals lengthen during ascent.
• B. The quadriceps and gluteals remain the same length during ascent.
• C. The quadriceps and gluteals shorten during ascent.
• D. The ascent is driven by passive tissue, not muscles.

Answer: (C)

Concentric contraction means a muscle shortens while producing force to create movement. In a squat ascent, you rise from the bottom by extending the knee and the hip. The quadriceps shorten to extend the knee, and the gluteals shorten to extend the hips, so both muscles engage in concentric contraction to lift your body. If those muscles were lengthening, that would be eccentric contraction (controlling descent). If they stayed the same length, that would be isometric (no length change with movement). The ascent isn’t driven by passive tissue alone; active muscle contraction is required to overcome gravity and lift the body.