Gohary T et al., International Journal of Therapies and Rehabilitation Research 2016; 5 (4):158-165 International Journal of Therapies and Rehabilitation Research [E-ISSN: 2278-0343] http://www.scopemed.org/?jid=12 IJTRR 2016, 5: 4 I doi: 10.5455/ijtrr.000000158 Effect of Muscle Length on Fatigue Induced by Low Frequency Current Stimulation in Human Medial Gastrocnemius Muscle Tarek M. El Gohary 1 , Sameh R. Ibrahim 2 *, and Waleed Salah El-din Mahmoud 2 1 Department of Biomechanics, Faculty of Physical Therapy, Cairo University, Egypt. PhD, PT,OCS, Cert. MDT, CEAS, Clinical BioKinesiologist. 2 Department of Basic Sciences, Faculty of Physical Therapy, Cairo University, Egypt. Corresponding author: Sameh Refaat Ibrahim. E-Mail: drsraibrahim@gmail.com Abstract Background: Muscle force is affected by many factors including muscle length. The exact mechanism of the effect of muscle length is not fully understood. Objective: to determine if motor neuron discharges accommodate changes imposed by changing Medial gastrocnemius muscle length following electrically fatiguing protocol. Methods: Randomized clinical trial was conducted on 60 untrained subjects aged (20-40 years) in isokinetic & electromyography lab of Faculty of Physical Therapy in august 2014. Both fatiguing short length group (FS) and fatiguing long length group (FL) underwent low frequency electrically fatiguing protocol. Main Outcome Measures: Outcome measures obtained pre and post the fatiguing protocol was the Root Mean Square (RMS). Results: There were extremely significant differences among the mean values of the pre- and post- test recordings in group I where the t value between the recordings was 8.032, and the P value was < 0.001, which indicated extremely significant differences between the recordings. While in group II, there were significant difference among the mean values of the pre- and post- test recordings where the t value between the recordings was 5.317, and the P value was < 0.01. Conclusion: Fatigue has been shown to be greater at long muscle lengths than at short muscle lengths following low frequency current fatiguing protocol. Key words: Muscle Length, Low frequency stimulation, Fatigue. Original Article Open Access