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  1. Y Kimura1,
  2. M Koyanagi2,
  3. K Koyanagi3,
  4. K Mukai4,
  5. N Naruhiko5,
  6. T Sakai6,
  7. S Tada1,
  8. Y Satoda7,
  9. Y Inoue8,
  10. A Inoue9
  1. 1Department of Rehabilitation Osaka University Hospital, Osaka, Japan
  2. 2Faculty of Biomedical Engineering, Osaka Electro-Communication University, Osaka, Japan
  3. 3Department of Intelligent Systems Design Engineering, Faculty of Engineering, Toyama Prefectural University, Toyama, Japan
  4. 4Faculty of Rehabilitation Shijonawate Gakuen University, Osaka, Japan
  5. 5Department of Rehabilitation, Higashi Toyonaka Watanabe Hospital, Osaka, Japan
  6. 6Department of Rehabilitation Science, Osaka Health Science University, Osaka, Japan
  7. 7Department of Rehabilitation, Toyonaka Watanabe Hospital, Osaka, Japan
  8. 8Department of Rehabilitation, Yukioka Hospital, Osaka, Japan
  9. 9ER Tech Co., Ltd, Osaka, Japan


Background Resistive lateral leg reach exercise (RLLR), a single-limb squat with resistance, increases load on the gluteal muscles and is effective for preventing knee valgus moment, a major factor in anterior cruciate ligament (ACL) injury. To enhance the load during RLLR, we devised a novel isokinetic exercise machine.

Objective To investigate the biomechanical and electromyographic (EMG) characteristics of the support leg during RLLR with isokinetic resistance (RLLR-I).

Design Quasi-experimental.

Setting Controlled laboratory setting.

Participants 8 asymptomatic recreational-level female college athletes.

Intervention Participants performed RLLR-I and lateral leg reach without resistance (LLR). The resistance device was set to 25 cm/s during RLLR-I. A three-dimensional motion capture system and force plate were used for motion analysis. Surface electrodes recorded the EMG at each muscle site: gluteus maximus (GMa), gluteus medius (GMe), rectus femoris, vastus medialis (VM), biceps femoris, adductor longus, soleus, and gastrocnemius.

Main outcome measurements The external knee valgus/varus moment and the internal joint moment of the support leg were calculated using software. EMG root mean squared amplitude was normalized as a percentage of maximum voluntary contraction (%MVC).

Results RLLR-I was characterized by a significantly larger internal hip abduction moment (2.2±1.0 Nm/kg) and significantly larger VM (152±54 %MVC), GMa (92±47 %MVC), and GMe (97±33 %MVC) activity compared with LLR (hip abduction moment: 1.5±0.7 Nm/kg; VM: 102±40 %MVC; GMa: 35±25 %MVC; and GMe: 38±13 %MVC). No significant external knee valgus moment occurred during RLLR-I.

Conclusion RLLR-I serves to increase the load on the VM and gluteal muscles and is effective for preventing external knee valgus moment. These findings suggest that this novel isokinetic exercise will be useful for preventing ACL injury and in rehabilitation after ACL reconstruction.

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