The forward lunge is a common exercise in both home fitness routines as well as with personal trainers and physical therapist to increase the load and capacity of the lower extremity during resistive training. While the forward lunge is very common, the biomechanics of how it is performed can vary greatly. These changes may affect how much joint stress the kneecap undergoes. Recently in the Journal of Orthopedic and Sports Therapy, a research article (1) was published regarding these alterations and how they affect the stress on the knee. The article addressed both the trunk and lower leg position and how they affect stresses at the knee during the forward lunge exercise.
Cory et al investigated three varied, but similar positions of a forward lunge. The three positions can be seen here.
What they found was the lead limb position influence both the lead and hind limb stress during the forward lunge. With a forward trunk and forward lower limb positions, an increased stress was reported on the forward limb. However, the stress on the hind limb as reduced compared to the FV and VV positions. The opposite was found during the other trunk and limb positions during the lunge. When the front leg was maintained as more vertical the force on the front knee limb was reduced, but at the expense of the rear limb which showed increased joint reaction forces during the FV and VV positions.
These results can yield clinical considerations of varying the lower leg and trunk positions during the forward lunge exercise to either avoid or achieve a desired performance or reaction force at the knee joint. Adding visual feedback to the trunk or the lower limb during the lunge may assist both the clinician and the client in achieving and maintaining the desired body position.
One option is placing the Motion Guidance visual feedback unit at the lower leg:
Another option to look at trunk lean and weight shift would be placing around the trunk:
can help provide and external focus to the biomechanics during the exercise giving an immediate visual cue to help performance and possible avoid long term “wear and tear” to the knees.
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1. ) Hoffman, Cory et al. Trunk and Shank Position Influences Patellofemoral Joint Stress in the Lean and Trail Limbs During the Forward Lunge Exercise. JOSPT VOl 47, No. pp 31-39, 1, Jan 201