A randomised clinical trial comparing the effectiveness of two exercise programmes on core strength and balance in healthy females
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Low back stability and low back strengthening exercises have emerged as popular techniques related to optimal athletic/occupational performance and the rehabilitation of painful backs (McGill 2001). The core provides local strength and balance as well as reduces the risk of low back injury (Kibler, Press and Sciascia 2006). Core strength is important in providing a solid base for the body to exert or resist forces. According to Anderson and Behm (2005), however, it is still uncertain as to which type of training is most effective in providing trunk and joint stability in its role in injury prevention and its contribution to balance. Aim: To determine if exercises performed on an unstable surface would result in greater balance improvements in healthy female participants when compared with exercises performed on a stable surface. Methods Forty asymptomatic females between the ages of 18 and 30 were recruited via self-selection. The study was a randomised clinical trial where all participants underwent a case history, a physical examination and a lumbar spine regional examination. Thereafter, participants were asked to stand on the Biosway Portable Balance System where baseline readings of the Clinical Test of Sensory Integration and Balance (CTSIB) and the Postural Stability Test were taken. The CTSIB has four test conditions – Condition 1: eyes open firm surface, Condition 2: eyes closed firm surface, Condition 3: eyes open foam surface, and Condition 4: eyes closed foam surface. The Postural Stability Test was presented in terms of overall postural stability, anterior/posterior stability and medial/lateral stability. Participants were then taught how to activate their core muscles by means of the prone coactivation exercise. A Pressure Biofeedback Unit was used to provide an objective measurement of the successful execution of the exercise. Participants were then allocated to either Group A or B and were taught how to perform the various core strength exercises. Participants in Group A performed the side bridge and single leg extension hold on a stable surface; participants in Group B performed the prone bridge and the quadruped reach on a Swiss ball. Participants were instructed to perform their respective exercises daily at home and they were also told the required number of sets repetitions they were to do. During the first week the participants were to perform three sets of 30 second holds daily, for the bridge exercises and three sets of 60 seconds for the extensor exercises. During the second week the participants were to perform four sets of 30 and 60 second holds, respectively. In the third and fourth weeks the participants were expected to perform five sets of 30 and 60 second holds respectively. The study participants reported to the Chiropractic Day Clinic once a week for four weeks and performed their exercises in the presence of the researcher. In the fourth week, however, the participants were asked to stand on the Biosway Portable Balance System and final readings of their CTSIB and Postural Stability Test were taken. All data was collected by the researcher. SPSS version 21 was used to analyse the data. A p value < 0.05 was considered as statistically significant. Intra-group analysis was done on each treatment group individually to assess the effect of the treatment over time using repeated measures ANOVA for each outcome separately. Inter-group analysis was achieved using repeated measures ANOVA with a between group effect of the intervention. A significant time x group intervention effect would signify a treatment effect. Inter-group correlations between changes in outcomes over time were achieved using Pearson’s correlation coefficient. Results: The mean (± SD) age of the participants was 22.1 years. In terms of the CTSIB test under condition 1 there was no statistically significant effect of the intervention (p=0.431), group B showed a decrease in their sway index after the intervention. Under condition 2 group A participants showed a decline in their sway index, however results were statistically insignificant (p=0.129). Both groups showed a decrease in sway index overtime under conditions 3 and 4 with group B showing a faster decline in sway index overtime under condition 3. Results remained statistically insignificant for both conditions (p=0.171) and (p=0.766) respectively. In terms of the Postural Stability Test the intervention was found to have no effect on the balance of study participants (p=0.548). Conclusion: The results of this study demonstrated a statistically insignificant improvement in the core strength and balance of the participants in both study groups. Taking into account the nature of the study population there is a possibility of a clinically significant effect were this study to be conducted on older individuals instead of younger individuals. For some of the outcomes measured there was a non-statistically significant trend towards an effect of the intervention, however for others both groups displayed the same trend over time. The power of the study to show a significant effect where one might have existed was low and thus the study should be repeated with a larger sample size using the outcomes which showed differential results between the treatment groups.