PNF and Movement 2023; 21(3): 309-317
A Comparison of Gluteus Maximus Muscle and Biceps Femoris Muscle Thickness According to Weight Load during Prone Hip Extension with Knee Flexion Exercises
Eun-Mi Jang, P.T., Ph.D.1⋅Da-Eun Jung, P.T., Ph.D.2†
1Department of Physical Therapy, College of Healthcare Medical Science and Engineering, Inje University
2Department of Physical Therapy, Gimhae College
Correspondence to: Da-Eun Jung (
Received: October 12, 2023; Revised: November 2, 2023; Accepted: November 8, 2023; Published online: December 31, 2023.
© Korea Proprioceptive Neuromuscular Facilitation Association. All rights reserved.

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Purpose: This study set out to investigate the effects of prone hip extension with knee flexion (PHEKF) exercises according to external load on the thickness of the gluteus maximus (Gmax) and biceps femoris (BF).
Methods: Twenty-three healthy men participated in this study. All subjects randomly practiced PHEKF under the burden of external loads created by sandbags (0 kg, 1 kg, and 2 kg). Rehabilitative ultrasound imaging (RUSI) was used to measure the thickness of the Gmax and BF during the PHEKF with different external loads.
Results: The thickness of the Gmax was highest during the 2 kg resistance exercise and lowest at 0 kg. The thickness of the Gmax was significantly increased at 1 kg and 2 kg compared to 0 kg and significantly increased at from 1 kg to 2 kg (p < 0.05). The thickness of the biceps femoris was highest at 0 kg and lowest at 2 kg. The thickness of the biceps femoris muscle was significantly reduced at 1 kg and 2 kg compared to 0 kg (p < 0.05), but there was no significant difference between 1 kg and 2 kg (p > 0.05).
Conclusion: The thickness of the Gmax was increased by applying PHEKF with a higher external load, whereas the muscle thickness of the biceps femoris decreased. These results suggest that the application of external loads during PHEKF exercises may be an effective method for selective strengthening of the Gmax.
Keywords: Ultrasonography, External loads, Muscle thickness, Gluteus maximus and Biceps femoris

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