Surface Electromyography (sEMG) Fatigue Analysis Comparing Chin Tuck against Resistance (CTAR) Against the Shaker Exercise

This poster was presented at the recent Dysphagia Research Society 23rd Annual Meeting at Illinois, Chicago, USA (12-14 March 2015).

Title: Surface Electromyography (sEMG) Fatigue Analysis Comparing Chin Tuck against Resistance (CTAR) Against the Shaker Exercise

Abstract:

Both Shaker and Chin Tuck against Resistance (CTAR) exercises were designed to improve swallowing through the strengthening of the suprahyoid muscles. However, a major limitation of the Shaker exercise was its early fatiguing of the sternocleidomastoid (SCM)(White et al., 2008). In this study, we investigated the extent CTAR recruits the suprahyoid and whether it fatigues SCM. Amplitude and fatigue analyses on sEMG data from 39 adults revealed that unlike Shaker exercise, CTAR was able to recruit the suprahyoid muscle, without substantially fatiguing SCM.

Introduction:

• Shaker exercise increases UES opening by improving contraction of suprahyoid muscles (Shaker et al., 1997).
• However, patient compliance was poor (50% attrition; e.g., Easterling et al., 2005).
• Poor compliance of Shaker exercise was linked to muscle fatigue of auxiliary muscles, namely SCM (White et al., 2008). CTAR exercise was a response to this limitation.
• Preliminary evidence for CTAR (N = 40 healthy adults; Yoon et al., 2014): (a) Greater sEMG values (amplitude) obtained from Suprahyoid during CTAR than during Shaker exercise. (b) Overall, participants reported CTAR as less strenuous.
• Research Questions:

1. Yoon et al’.s data was based on 10-sec isometric trials. The actual CTAR and Shaker exercises require 60 secs each. Will evidence on suprahyoid muscle strength still hold for CTAR when exercise duration is increased to 60 secs?
2. Main disadvantage for Shaker exercise was its fatiguing of auxiliary muscles beyond the suprahyoid, i.e., SCM. Is CTAR able to demonstrate that it does not suffer this same limitation (i.e., fatiguing of SCM)?

Method:

Participants:

• N = 39 healthy adults (20 males, 19 females; mean age = 29.82, SD = 5.09).
• Each participant completed CTAR and Shaker twice in randomized counterbalanced order. 4-min rest in between each exercise.

sEMG Recording:

• Single-use pre-gelled electrode patches used (Figure 1; one placed on suprahyoid, the other on SCM).
• sEMG collected by MyoTrac Infiniti encoder (2048 Hz).

CTAR Exercise (Figure 2):

• Seated upright; shoulders not slouched.
• Executed chin tuck, squeezing an inflatable rubber ball (12 cm diameter) between the base of chin and manubrium sterni for 60 secs.

Shaker Exercise (Figure 3):

• Lie supine on an exercise mat.
• Perform a head lift for 60 secs, shoulder not raised.

Data Processing:

First and final 7 secs from each exercise interval discarded to eliminate noise. – MATLAB (Welsch Method) used to generate the power spectra density data.

Results:

• 2 x 2 ANOVA was conducted on each variable.
• Suprahyoid registered sig. greater (ps < .001) values during CTAR than Shaker. SCM registered sig. greater (ps < .001) values during Shaker than CTAR.
• Suprahyoid registered sig. greater (ps ≤ .02) fatigue during CTAR than Shaker. SCM registered sig. greater (ps ≤ .002) fatigue during Shaker than CTAR.
• Rate of change in fatigue for Suprahyoid: CTAR = Shaker (ps > .10). Rate of change in fatigue for SCM: Sig. lesser (ps ≤ .01) during CTAR than Shaker

Discussion:

• Converging data across two amplitude measures suggest that motor unit recruitment (thus muscle strength) for Suprahyoid was significantly greater during CTAR.
• Converging data across four fatigue measures suggest that fatigue in SCM was significantly lesser during CTAR than the Shaker exercise.
• Extends supporting evidence on CTAR’s usefulness in targeting Suprahyoid (SCM not as actively recruited), when conducted in its full 60-secs duration.
• Clinical trials of CTAR on dysphagic patients recommended as follow-up.