Research: Effect of Exercises on Strength & Stability

Research Paper Title

The Effect of Core and Lower Limb Exercises on Trunk Strength and Lower Limb Stability on Australian Soldiers.

Study Design

A before and after design in the collection of data and using analyses of variance to examine the changes in each test score.

Objectives

The objectives and hypotheses of this study were:

  1. Do  specific core exercises, incorporating the lower limbs, improve lower limb stability and trunk core muscle strength?;
  2. Can the Star Excursion Balance Test be used as a measure of ankle and lower limb stability without a history of ankle instability?;
  3. Can static core tests be used as a measure of core stability?; and
  4. Is the Cumberland Ankle Instability Tool (CAIT) questionnaire sufficiently sensitive to show any changes to ankle instability following the outcomes of this study?

Background

An earlier study undertaken by Sellentin and Sanchez (2011) identified specific injuries sustained by Australian garrison soldiers of the 16 Air Defence Regiment. These injuries involved the  neck, low back, knee and ankle. This current study was designed to address these injuries by providing exercises to specifically strengthen the core and lower limb muscles and to improve proprioception and muscle movement patterns, with the aim of reducing the number of injuries in Australian soldiers.

Methods

Eight young adult males volunteered for this study (mean age of 22 years). Female Australian soldiers did not participate in this study, as there were none available at the time and  there were very few women in the Regiment. The eight male subjects undertook a twelve week supervised exercise programme loosely based on the validated FIFA 11+ programme. Subjects performed specific exercises over twelve weeks which were gradually increased in intensity, difficulty and resistance week by week.

Each subject also completed a CAIT questionnaire before and after the 12 week exercise programme. In order to measure any effect from the exercise programme.  Each subject was asked to perform a series of sustained flexion, extension, side holds and prone hold tests and the Star Excursion Balance Test (SEBT), which were recorded before and after the exercise programme as assessment tools. The SEBT was also used to assess if there were any sensorimotor deficits related to chronic ankle instability in any of the subjects.

Researchers chose to use the SEBT as it has strong intra-tester and inter-tester reliability, is sensitive in the detection of functional deficits associated with chronic ankle instability, and with the possibility that this instability might be related to performance deficits in the entire affected extremity (Hertel et al 2006). This is particularly relevant when one of the purposes of the study was to examine if the exercise programme could reduce the risk to the knee and ankle by improving lower limb stability.

Results

Even though the sample size was small, there were significant effects in the before and after tests following the 12 week exercise programme:

  • The Sustained Flexion test showed significant improvement.
  • The Prone Hold showed an increase but not a significant change.
  • The Left and Right Side Bridge showed a levelling  out.
  • The SEBT showed significant improvement in all of the Posterior reach directions, improvements in the Lateral and Medial reach (left and right limb stance), and improvement in the Anterior reach direction (right limb stance). The Anterior reach direction showed no improvement.
  • Averaging over all the scores of all the tests of the SEBT  showed a significant improvement.
  • If the SEBT composite score of Anterior, Posteromedial and Posterolateral reach is taken as a predictor of lower extremity injury (Plisky et al. 2006), the results show a very strong improvement in post exercise scores. There was a shift in each subject’s scores in the current study from below the critical 94% figure (identified by Plisky et al (2006)  as a risk factor in  lower extremity injury) to above 94% following the exercise program.
  • The CAIT showed a mixed result with one subject improving their ankle functional instability (FI) and two subjects showing a decreased score following the exercise programme.

Conclusion

The results from this study support the hypothesis that specific core and balance exercises improve core strength and lower limb balance. There is thus a very strong indication for its use in injury prevention.

Source: Sellentin, R. & Jones, R. (2013) The Effect of Core and Lower Limb Exercises on Trunk Strength and Lower Limb Stability on Australian Soldiers. Journal of Military and Veteran’s Health. 20(4).

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