On sample size, three factors to be considered in the calculation of sample size are as follows: The level of statistical significance, normally 5%; The power, i.e. the probability to detect (reach statistical significance) for a given effect size, will be 90%; and The effect size is the difference between the two means you want to compare divided by the standard deviation. In this case, the affect size of 0.4 as found in recent meta-analysis for similar intervention, will be used for this calculation. This gives 81 participants per group. However, to factor in a 10% loss to follow-up, (8 subjects) will be added making the total number in each group to be 89.