Two modes of weight training programs and patellar stabilization

Abstract

Context: Underconditioned patellar stabilizing muscles could be a predisposing factor for patellar instability.

Objective: To examine the effect of 2 modes of weight training on the size of the vastus medialis obliquus (VMO), the resting position and passive mobility of the patella, and the strength of the knee extensor muscles.

Design: Prospective intervention, repeated measures in 3 groups.

Setting: Orthopaedic and sports sciences research laboratory.

Patients or other participants: 48 healthy adults free from back and lower extremity injuries.

Intervention(s): Participants were randomly assigned to muscle hypertrophy training, muscle strength training, or the control group. Those in the training groups pursued training 3 times per week for 8 weeks.

Main outcome measure(s): Magnetic resonance imaging and ultrasound cross-sectional area of the VMO, patellar tilt angle on magnetic resonance imaging, instrumented passive patellar mobility, and isometric knee extension torque of the dominant leg.

Results: Participants in both training groups had comparable gains in VMO size, passive patellar stability, and knee extension force, all of which were greater than for the control group (P < .05).

Conclusions: Both short-term muscle hypertrophy and strength training programs can reinforce the patellar stabilizers in previously untrained volunteers.

Keywords: magnetic resonance imaging; patellofemoral joint; quadriceps muscles.

Figure 1. Selected axial magnetic resonance images. A, Vastus medialis obliquus (VMO) muscle at the distal 10% of the length between the anterior-superior iliac spine and the lateral knee joint line, and B, at the midtransverse patella level.

Figure 2. A, Hands-free ultrasound imaging. B, Corresponding ultrasound image. The laser provided a reference for positioning the participant and locating the vastus medialis obliquus.

Figure 3. The patellar tilt angle (PTA) is formed by the intersection of the lateral patellar facet line and the posterior condylar reference line.

Figure 4. Passive patellar mobility measurement. E indicates electromagnetic tracker; M, mechanomyography biofeedback; F, force gauge.

Figure 5. Magnetic resonance image of the vastus medialis obliquus (VMO) of the right leg, pretraining (Pre) and posttraining (Post), from a representative volunteer in the muscle hypertrophy training group.