1. Rhythmic Auditory Stimulation (RAS)  Developed primarily by Thaut, McIntosh, & Rice at the CBRM at Colorado State University  NMT technique utilizing the physiological effects of rhythm on the motor system to increase the efficiency of controlled movement patterns during rehabilitation.  Enhancement of gait is mediated by an entrainment effect where movement frequencies and motor programs entrain to rhythm through anticipatory cuing of functional movement patterns.

2. RAS Uses  Immediate entrainment stimulus providing rhythmic cues during movement.  Listen to music with strong rhythmic pulse while walking to enhance walking tempo, balance, and control of muscles and limbs.  Stimulus for training where patients train with RAS for a prescribed period of time in order to achieve more functional gait patterns which they then transfer to walking without rhythmic facilitation.

3. Mechanisms  Rhythmic Entrainment  Priming of the Auditory Pathway  Cuing of the Movement Period  Step-Wise Limit Cycle Entrainment

4. Rhythmic Entrainment  Physiological basis for the perception of rhythm is the detection of periodicity patterns in amplitude modulations of sound  External rhythm serves as an external oscillator which has a “magnet” effect on one’s internal timekeeper.  Strength of the effect is substantiated by the observation that motor responses can be entrained by rhythmic patterns even at levels that are imperceptible.

5. Auditory-Spinal Facilitation  Physiological entrainment of muscle activation through rhythm perception takes place via reticulospinal pathways.  Neurons in the spinal cord become excited as a result of auditory perception.  Support for these concepts were observed in research when many components of the neural synchronization network were already activated and “entrained” simply by listening to rhythm.  One result of neuronal excitement is the “priming” or “readying” of muscle groups utilized in movement, which has a facilitative effect on subsequent motor functioning.

6. Cuing of the Movement Period  Period Synchronization - adaptation of the movement duration to the rhythmic stimulus duration  Phase Synchronization - ISI and IRI are closely matched although period synchronization is not behaviorally observable.  Kinematic models show that period (or frequency) entrainment results in enhanced kinematic stability through the stabilization of the following parameters: acceleration, velocity, trajectory).

7. Step-Wise Limit Cycle Entrainment (SLICE)  RAS frequencies (tempi) need to be set initially at a pt.s ‘resonant’ (current or intrinsic) frequency of movement.  Limit cycles are frequencies at which any moving system performs optimally (developed in the fields of engineering, physics)  Hence, RAS frequencies should be adapted to a person’s current limit cycle, i.e. the current step cadence.

8. SLICE cont’d  Initial purpose of RAS is to stabilize movement parameters at a pt.s current limit-cycle.  New limit cycles can be gradually entrained through a step-wide incremental process to approximate a pt.s pre-morbid limit-cycle.  Ex. When using RAS to increase cadence of PD pt.s, stride lengths will increase also due to the mechanical properties of the gait generating system.

9. SLICE cont’d  In the case of pt. who has a nearly normal cadence with shortened stride length, RAS is used to match the current cadence or a slightly slower one in order to increase stride length through added kinematic stability which is present due to the entrainment process.  SLICE - most commonly used RAS protocol in the treatment of gait disorders.

10. RAS Gait Training Procedures  Assessment  Resonant Frequency Entrainment  Frequency Modulation  Advanced Adaptive Gait  Fading  Reassessment

11. Cadence Assessment  Cadence - steps/minute  Client walks for 60 seconds while you count each step; walks for 30 seconds then multiply steps by 2)  This is unaccompanied by music.  Avg. cadence for an adult is 105-120 steps/min but is age related.

12. Velocity Assessment  Velocity - Meters/minute or feet/minute  Measure distance across time  Pt. walks for 60 seconds and you measure how many meters or feet they walked (multiply by 2 if walking for only 30 seconds)  Difficult to do because of space limitations.  Hospitals usually have 1-foot floor tiles. Count the tiles to get a feet/min measurement, then divide by 3.281 for meters/min (1 meter = 3.281 ft.)

13. Velocity Assessment cont’d  Measure off 10 meters on the floor.  Time the number of seconds it takes a pt. to walk 10 meters. *Have them start a few ft. before and continue going for a few ft. past the line.  Divide the number of seconds by 60 (60 sec/min)  Divide 10 meters by the number of minutes which gives you the meters/minute value.  Ex. Pt. walks 10 meters in 7 seconds  7 sec/60 sec/min =.117 minutes  10 meters/.117 minutes = 85.5 meters/minute  Avg. normal velocity in adults is 80 m/m, but is age dependent.

14. Stride Length  Divide velocity by cadence.  This will provide the number of meters for each step. (*This in inaccurate if there is uneven step length between the right and left legs)  Multiply this figure by 2 and this will give you the average stride length.  Ex. 70 meters/min (velocity) / 80 steps/min (cadence) =.875 meters/step .875 meters/step x 2 steps/stride = 1.75 meters avg. stride length.

15. Step 2 Resonant Frequency Entrainment  Match RAS frequency (music tempo) to gait cadence and walk with patient.  Pt.s who are not ready for sustained walking exercises can practice specific pre-gait exercises, e.g. weight shifting - front to back, side to side, etc. 6/8 tempo usually more preferable  Therapist may need to cue proper gait mechanics, e.g. stride length, arm swing, posture, toe clearance, heel strike, etc.

16. Step 3 Frequency Modulation  Increase tempo by no less than 5% ~ an increase that still allows them to maintain proper mechanics.  Again use verbal cues, but feedback should be kept to a minimum as you may interfere with rhythm perception and its subsequent effects  Clients who have attention problems may need enhancing verbal cues initially, e.g. left-right, 1-2  Generally, frequencies (tempi) that are more closely aligned with a pt.s pre-morbid state tend to more have the strongest effect on overall gait patterns.  In some cases, a deceleration in RAS frequency is indicated for pt. groups who have the proclivity for unsafe walking patterns.

17. Considerations  2/4 or 4/4 meter with strong beat accents (1 & 3)  If a pt. utilizes an assistive device, cane or walker, a 3-step pattern may be more useful, e.g. step, step, walker  The motivational quality of music is a bonus secondary effect ~ client preferences. Note that some diagnoses do not perceive complex acoustic patterns well so very simple music or simply a metronomic click would work best.