Aussie Current Dose Parameters

Aussie Current is a burst modulated alternating current (BMAC) used for muscle stimulation to elicit torque production.  Other electrophyscial agents (EPA) that are commonly used for muscle strengthening are Russian Current and Pulsed Current (PC), via interferential and transcutaneous electrical nerve stimulation (TENS) modalities respectively.  However each of the modes have differing dosage parameters. 

Aussie Current is similar to Russian Current as both are delivered to the muscles by a medium frequency current, but it is defined by the application of 1-kHz alternating current (AC), in 50-Hz bursts of 4ms duration, with a 20% duty cycle.  Russian current, on the other hand, uses a higher frequency of 2.5-kHz, and longer durations of 50-Hz bursts of 10ms duration, with a 50% duty cycle (Ward, Oliver & Buccella, 2006).  Alternatively, PC differs from Aussie and Russian Currents as it is a low frequency monophasic direct current (DC) stimulus.  No one dosage parameter defines PC, however a pulse frequency of 50 Hz and phase durations of both 200 us and 500 us were investigated in the Ward, Oliver and Buccella’s 2006 study of torque production and associated discomfort and thus will be referred to in this blog.





Comparison of the 4 waveform parameters investigated in Ward, A. Oliver, W. Buccella, D. (2006). Wrist Extensor Torque Production and Discomfort Associated With Low-Frequency and Burst-Modulated Kilohertz-Frequency Currents.





Traditionally muscle strengthening programs by electrical stimulation were performed by using Russian Current, which gained interest in western countries in the late 1970’s.  Russian Current also investigated by Ward and Robertson in a 1998 study of “Variation in torque production with frequency using medium frequency alternating current” found that the lower 1-kHz frequency was optimal for torque production and that a lower duty cycle provide greater comfort, parameters which now define Aussie Current.  Further investigation of torque production and patient perceived discomfort it was discovered that higher frequency (4kHz) and lower duty cycles (20% duty cycle) minimized participant discomfort (Ward et al, 2006).   






Reported level of discomfort between the 4 different stimuli.



Maximal electrically induced torque (MEIT) examined.



 Whilst there was no significant difference in maximal electrically induced torque (MEIT) produced across the four test parameters, Aussie Current produced the highest and Russian Current the lowest.  There was however a significant difference in the level of discomfort observed by the patient. The level of discomfort was far greater with the PC stimulus decreasing significantly as frequency increases. Aussie current recorded the second lowest level of discomfort with Russian Current providing the lowest ratings of discomfort (Ward et al, 2006).   

From the literature it can be inferred that Aussie Current aims to maximise torque production by the use of 1-kHz frequency and the lower duty cycle of 20% to increase comfort.  Thereby utilising the benefits of both parameters, which would be expected to increase subject compliance. 

References

Ward, A. Oliver, W. Buccella, D. (2006). Wrist Extensor Torque Production and Discomfort Associated With Low-Frequency and Burst-Modulated Kilohertz-Frequency Currents. Physical Therapy, 2006(86). 1360-1367 Doi:10.2522/ptj.20050300
http://physther.org/content/86/10/1360.full.pdf

Ward, A. Robertson, V. (1998). Variation in torque production with frequency using medium frequency alternating current. Arch Phys Med Rehabil, 1998 (79). 1399-1404 http://download.journals.elsevierhealth.com/pdfs/journals/0003-9993/PIIS0003999398902349.pdf