Anterior cruciate ligament strain and tensile forces for weight-bearing and non-weight-bearing exercises - Part 2
This second part examines the strains and forces the ACL receives during weight-bearing (WB) exercises for ACL reconstruction rehabilitation.
- Squats and Lunges (performed heels on the ground, trunk tilted >30° forward and not allowing the knees beyond the toes) induce little to no strain on the ACL, by increased hamstrings co-activity.
- Leg Press produces no shear or tensile force on the ACL, can be progressed by increasing knee flexion angles and resistance (up to 12RM), and helps recruiting knee and hip musculature.
- Cycling, which produces very low tensile forces on the ACL at various intensities and speeds, can be considered safe to improve patients muscular and cardiovascular fitness.
- Plyometric jumps produce similar strains on the ACL than Seated Knee Extension. Double-leg drops can be progressed to single-leg drops at higher heights. Proper landing technique can also minimise ACL loading (landing softly with knee flexion, forward trunk tilt, and controlled knee valgus, hip adduction and internal rotation).
- Walking induces ACL strains comparable to NWB Knee Extension; gait retraining should therefore be incorporated once pain, ROM and swelling are controlled.
In summary, strains on the ACL graft peak at 10-30° of knee flexion, reduce between 30-60° and disappear after 60°; NWB exercises induce more strains than WB. Proper proprioception and motor control also minimise strains on the ACL graft. > From: Escamilla et al., J Orthop Sports Phys Ther 42 (2012) 208-220. All rights reserved to the Journal of Orthopaedic & Sports Physical Therapy.
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