Application Notes
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Better Sessions Moving the ERGYS Session Checklist E'trode Placement

Getting the Most from Your ERGYS Sessions

Stimulus Scaling

The ERGYS2 software calculates maximum stimulus differently than previous versions of the ERGYS software. Before, with versions D.0 and earlier, reaching the maximum stimulus of 140 milliamps on a channel required a threshold setting of at least 60 mA for that channel. Version E.0 offered a slight improvement by automatically scaling the channel with the highest threshold setting to 140 mA when 'Percent Max Stimulus' was at 100%. However, this method still "underscaled" those channels with thresholds under the maximum threshold.

With version F.0 and higher, every channel is scaled independently based on the channel's Maximum Stimulus setting. Under normal circumstances, every channel will reach 140 mA, regardless of the channel's threshold setting.

Stimulus during Warm-up and Cool-down with the new software is the same as with previous software versions, where stimulus is pulsed between 50% and 100% of the threshold.

When new limits are set for the Maximum Stimulus Levels, the thresholds are automatically reset to 0 mA and must be reentered before the start of the next run.

Definition of Pedaling Resistance

Pedaling resistance levels for ergometers are typically quantified in units known as kiloponds (Kp). This is a measure of the drag force applied tangential to the flywheel.

1 Kp = force generated by the weight of a 1 Kg mass

The ERGYS and REGYS offer resistance levels ranging from zero to 7/8 kiloponds in 1/8 kilopond increments.

As kiloponds are a measure of drag or torque, the following conversions may be useful for converting kiloponds to inch-pounds, a more standard unit of torque.

1/8 Kp = 2.68 inch-pounds (0.233 foot-pounds) of drag at flywheel axle

= 10.4 inch-pounds (0.865 foot-pounds) of drag at pedal crank


Calculating Power and Work

Using average RPM and average resistance, it is possible to calculate power and energy output (work).

Power (in Watts) = 0.983 x average Kp x average RPM

Note: 0.983 is a constant derived by "plugging in" the known values of the ERGYS geometry into the "POWER = FORCE x DISTANCE/TIME" equation.

Work (in joules) = POWER (in Watts) x RUN TIME (in seconds)

Example: AVG KP = 1.9 x 1/8 Kp Converted to Kp: 1.9 ÷ 8 = 0.2375

AVG RPM = 48

RUN TIME = 30 minutes = 1800 seconds

POWER = 0.983 x 0.2375 Kp x 48 RPM = 11.2 Watts

WORK (in joules) = 11.2 Watts x 1800 seconds = 20,160 joules


Glossary of Electrical Stimulus Terms

Balanced Charged - A characteristic of a waveform where the sum of the positive phase(s) is electrically equal to the sum of the negative phase(s). All ERGYS2se waveforms except the ERGYS1 compatible waveform are balanced charged.

Biphasic - A stimulus waveform that has both a negative and a positive phase. A sine wave is a classic example of a biphasic waveform.

Camel Back - A biphasic stimulus waveform with two positive "humps" (phases) and one negative hump. The area of the positive current is equal to the area of the negative current (i.e., the waveform is balanced charged).

Channel - The source of stimulus on the ERGYS2se. There are six channels with independently programmable pulse amplitudes. The pulse duration, waveshape, and frequency are the same among all channels. Each channel is connected to the patient via surface electrodes. Impedance is measured through these channels.

Interphase Interval - The time during a pulse, between two successive phases, when the stimulus amplitude is 0 milliamps.

Phase Duration - The time from the start until the end of one phase of a stimulus pulse, usually expressed in microseconds. This measurement is usually made at the amplitude where the phase is at its longest (e.g., from zero crossing to the next zero crossing on a sine wave).

Pulse Amplitude - The measure of the peak stimulus current with respect to a 0 volt baseline. On the ERGYS, the maximum pulse amplitudes can be set at the Max Stim Display. The default for the ERGYS 1 and ERGYS2se is 140 milliamps. The pulse amplitudes are adjusted automatically during an ERGYS run to control the rider to 50 RPM. This is the essence of the ERGYS closed-loop control.

Pulse Duration - The time from the start until the end of a stimulus pulse, usually expressed in microseconds. On waveforms with no interphase interval, the pulse duration is the sum of the positive and negative phases.

Stimulus Frequency - The number of stimulus pulses in 1 second, expressed in Hertz (Hz) or pulses per second (PPS).

Waveform - A stimulus pulse. The components of a waveform are the phases (positive, negative, and interphase), the shape (e.g., sine, Camel Back, ERGYS I compatible), and the amplitude.

Waveshape - the appearance of the stimulus waveform as viewed on an oscilloscope. Waveshapes are described in terms such as monophasic. or biphasic, sinusoid or rectangular, balanced charged or not balanced charged.


Getting the Most out of Your Bioflex or Stimwear

The Bioflex and Stimwear electrode garments for the ERGYS and REGYS are designed to make life easier for riders, clinicians, and attendants. The garments are designed to ensure proper electrode placement and connections, to decrease prep time, and to eliminate the skin irritation often associated with the adhesives of "standard" electrode configurations.

By following a few simple guidelines, you will be assured of getting the best performance and the longest life out of your Bioflex or Stimwear electrode garment.

Caring for the Garment

1. When disconnecting from the ERGYS or REGYS, always pull the mating connectors apart at the black and white molded plastic connectors. Do not unplug the connectors by pulling on the cables.

2. It is possible to machine wash the Bioflex and Stimwear. The sooner the garment is washed after a session, the easier it will be to completely wash away the gel.

3. Always "mate" all of the hook fasteners to their associated loop sections before washing.

4. It is best to place the garment in a mesh "delicates" bag before washing.

5. Always wash the garment on the most gentle cycle in cold water.

6. Air dry the garment after washing. Hang the garment so that there is no undue pulling on the waistband or elsewhere due to the weight of the water in the just-washed garment.

Life of the Garment

1. The Antron-Nylon fabric of both the Stimwear and the Bioflex should last 1 to 2 years depending on frequency of use and the care in washing.

2. The carbon electrodes in the garment should be replaced every 4 to 8 months. A decrease in session performance (run times or resistance levels) and intermittent open lead messages are the primary indicators that the electrodes are worn out. The Bioflex allows for the user to replace the electrodes. Simply call Therapeutic Alliances and order 12 of the part number 08-2070 electrodes. Replacement of the Stimwear electrodes requires the skill of a trained seamstress, and, as such, the garment must be returned to Therapeutic Alliances.

3. The Bioflex and Stimwear use the same cabling system. This cabling normally will last the life of the garment, 1 - 2 years. When connecting the garment to the ERGYS or REGYS, do not force the connectors together, as this can break the pins of the connectors. It is always important to check that the pins of the connectors are straight before mating the connectors. Likewise, it is important to pull on only the molded black and white plastic connectors when disconnecting the garment from the ERGYS or REGYS. Unplugging the connectors by pulling on the wires can damage the cables and decrease the life of the garment.



Therapeutic Alliances Inc.
333 North Broad Street - Fairborn, OH 45324  USA
(937) 879-0734 - (937) 879-5211 (fax)

This page and all Therapeutic Alliances-designed link pages are Copyright 1996-2012 Therapeutic Alliances Incorporated, Fairborn, Ohio USA. All rights reserved. Therapeutic Alliances Inc., ERGYS®, REGYS, SpectraSTIM®, NeuroEDUCATOR®, Stimwear®, "You Are the Moving Part," and "The Power of Your Muscles" are trademarks of Therapeutic Alliances Inc. Control Bionics and NeuroSwitch are trademarks of Control Bionics Inc. Parastep is a trademark of Sigmedics Inc.

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