Enhanced balance associated with coordination training with stochastic resonance stimulation in subjects with functional ankle instability: an experimental trial

Abstract

Background: Ankle sprains are common injuries that often lead to functional ankle instability (FAI), which is a pathology defined by sensations of instability at the ankle and recurrent ankle sprain injury. Poor postural stability has been associated with FAI, and sports medicine clinicians rehabilitate balance deficits to prevent ankle sprains. Subsensory electrical noise known as stochastic resonance (SR) stimulation has been used in conjunction with coordination training to improve dynamic postural instabilities associated with FAI. However, unlike static postural deficits, dynamic impairments have not been indicative of ankle sprain injury. Therefore, the purpose of this study was to examine the effects of coordination training with or without SR stimulation on static postural stability. Improving postural instabilities associated with FAI has implications for increasing ankle joint stability and decreasing recurrent ankle sprains.

Methods: This study was conducted in a research laboratory. Thirty subjects with FAI were randomly assigned to either a: 1) conventional coordination training group (CCT); 2) SR stimulation coordination training group (SCT); or 3) control group. Training groups performed coordination exercises for six weeks. The SCT group received SR stimulation during training, while the CCT group only performed coordination training. Single leg postural stability was measured after the completion of balance training. Static postural stability was quantified on a force plate using anterior/posterior (A/P) and medial/lateral (M/L) center-of-pressure velocity (COPvel), M/L COP standard deviation (COPsd), M/L COP maximum excursion (COPmax), and COP area (COParea).

Results: Treatment effects comparing posttest to pretest COP measures were highest for the SCT group. At posttest, the SCT group had reduced A/P COPvel (2.3 +/- 0.4 cm/s vs. 2.7 +/- 0.6 cm/s), M/L COPvel (2.6 +/- 0.5 cm/s vs. 2.9 +/- 0.5 cm/s), M/L COPsd (0.63 +/- 0.12 cm vs. 0.73 +/- 0.11 cm), M/L COPmax (1.76 +/- 0.25 cm vs. 1.98 +/- 0.25 cm), and COParea (0.13 +/- 0.03 cm2 vs. 0.16 +/- 0.04 cm2) than the pooled means of the CCT and control groups (P < 0.05).

Conclusion: Reduced values in COP measures indicated postural stability improvements. Thus, six weeks of coordination training with SR stimulation enhanced postural stability. Future research should examine the use of SR stimulation for decreasing recurrent ankle sprain injury in physically active individuals with FAI.

Figure 1

Means And Standard Deviations Of Anterior/Posterior Center-Of-Pressure Velocity (A/P COPvel). *The stochastic resonance stimulation coordination training (SCT) group had slower posttest A/P COPvel than the posttest pooled mean of the control and conventional coordination training (CCT) groups. Pretest = A/P COPvel pooled pretest means of all groups.

Figure 2

Means And Standard Deviations Of Medial/Lateral Center-Of-Pressure Velocity (M/L COPvel). *The stochastic resonance stimulation coordination training (SCT) group had slower posttest M/L COPvel than the posttest pooled mean of the control and conventional coordination training (CCT) groups. Pretest = M/L COPvel pooled pretest means of all groups.

Figure 3

Means And Standard Deviations Of Medial/Lateral Center-Of-Pressure Standard Deviation (M/L COPsd). *The stochastic resonance stimulation coordination training (SCT) group had reduced posttest M/L COPsd than the posttest pooled mean of the control and conventional coordination training (CCT) groups. Pretest = M/L COPsd pooled pretest means of all groups.

Figure 4

Means And Standard Deviations Of Medial/Lateral Center-Of-Pressure Maximum Excursion (M/L COPmax). *The stochastic resonance stimulation coordination training (SCT) group had shorter posttest M/L COPmax than the posttest pooled mean of the control and conventional coordination training (CCT) groups. Pretest = M/L COPmax pooled pretest means of all groups.

Figure 5

Means And Standard Deviations Of Center-Of-Pressure Area (COParea). *The stochastic resonance stimulation coordination training (SCT) group had less posttest COParea than the posttest pooled mean of the control and conventional coordination training (CCT) groups. Pretest = COParea pooled pretest means of all groups.