Joint Kinetics and Kinematics During Common Lower Limb Rehabilitation Exercises.
Level 3 - non-randomized controlled study
Within-subject comparative biomechanical laboratory study.
PubMed 26418958 · doi:10.4085/1062-6050-50.9.05
What was done
Nine healthy men (mean age 22.1 ± 1.3 years, height 1.76 ± 0.08 m, body mass 80.1 ± 12.2 kg) performed three unilateral body-weight exercises: single-legged squat, forward lunge, and reverse lunge. Motion capture and two force plates were used to assess 3D kinematics and kinetics, specifically measuring peak vertical ground reaction forces, maximum joint angles, and peak sagittal-plane joint moments at the ankle, knee, and hip.
What was found
Eccentric and concentric peak vertical ground reaction forces were significantly higher during the single-legged squat compared with both lunge variations (P ≤ .001). Maximum knee and hip flexion angles were greater in both lunge variations than in the single-legged squat (P < .001), with no difference between lunges (P > .05). Dorsiflexion was greater during the single-legged squat than either lunge variation (P < .05; lunge comparison P = .70). Hip-joint moments were greatest in the forward lunge compared with the reverse lunge (P = .003) and single-legged squat (P = .011). Knee-joint moments were higher in the single-legged squat than the reverse lunge (P < .001), but did not differ from the forward lunge (P = .41). Ankle-joint moments were highest during the single-legged squat compared to the forward lunge (P = .002) and reverse lunge (P < .001).
Why it matters
These findings provide objective joint-loading data to guide exercise progression in lower-extremity rehabilitation, indicating that hip loading is maximized during forward lunges, while ankle and knee demands are greatest during single-legged squats.
Limits
The sample size was very small (n = 9) and restricted to healthy young men, limiting generalizability to female athletes, older adults, or patients recovering from injury. Biomechanical loading in a controlled laboratory setting may not directly reflect functional recovery or clinical rehabilitation outcomes.