Feedback from participants and subsequent modifications made to methods

made to methods

More participants expressed a preference for wearing the Actiheart above the breast than below. In some women, contact between the central electrode and the skin above the breast was disrupted by the movement and the position of cleavage. This could easily be avoided by placing the electrode slightly higher on the chest. On slim women the position of the left electrode was necessarily nearer the under arm, which had the potential to cause inconvenience, but this issue was less problematic in average or larger sized women.

Two significant problems arose when women wore the electrodes below the breast. Firstly, the central section of the Actiheart often rubbed against the

underside of the bra. Secondly, in larger women the movement of fat and the presence of sweat in the abdominal area sometimes caused the electrode to adhere

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poorly to the skin, causing a loss of contact between skin and electrode, with two Actihearts becoming detached. These issues might be particularly challenging in postnatal women who are breastfeeding.

Participants experienced itching whilst wearing the electrodes during 10 out of 18 sessions, especially when applied after the skin preparation. In view of the quality of the data (indicating good contact between electrode and skin) and the skin reaction issues, it was decided not to perform skin abrasion prior to applying the Actihearts. Some participants reported that the areas under the electrodes became itchy after a few days of wear. This indicated that if worn for more than two to three days, electrodes may have needed to be replaced. In the main RCT we therefore advised participants to keep the Actiheart on whenever possible but provided spare electrodes in case a change was necessary. Pain when removing the electrodes was experienced by participants after four out of 18 sessions and skin was sometimes red following electrode removal (6/18 sessions). On this basis participants in the RCT were recommend to apply moisturising cream to any sore areas after Actiheart removal.

As a result of this pilot is was clear that an Actiheart, if fitted in either position, had the potential to be inconvenient to a mother if she was breastfeeding during the RCT. If this was raised by a mother, they were advised that wearing something to cover the Actiheart so the baby was not attracted to it (and did not try to pull at it) might be helpful. If this was not possible, women were advised to remove the Actiheart while breastfeeding and replace it afterwards with new electrodes.

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2.6.3.1 Consideration of alternative objective measures

The use of Actihearts was specified in the funding application for the main RCT. This decision was based both on the significant advantage in data accuracy afforded by their ability to estimate energy expenditure using accelerometry and heart rate data (155), and their previous successful use in another trial within the department (141). In light of the skin sensitivity issues raised in this preparatory work and the potential for such factors to negatively affect retention to the study, it is possible that other accelerometers may have been more suitable. Waist worn accelerometers such as the Actigraph and ActivPAL (151, 152) may have provided a less accurate assessment of energy expenditure but as they are not attached to the skin using electrodes, they may have been more acceptable to the population. The cost of the Actihearts

prohibited purchasing alternative devices prior to, or during the RCT. An alternative strategy may have been to loan the Actihearts in order to conduct the pilot test, we would then have been able to reconsider the decision to use them in the main trial after the findings of the pilot.

2.7

Conclusions

During this preparatory work, no difference in data quality was found when wearing the Actihearts above and below the breast. The decision as to where to fit Actihearts in postnatal women was therefore based on practical factors and the preferences of women themselves. More participants preferred wearing the Actiheart above the breast than below. Considering the RCT study population of postnatal women, the problems experienced regarding poor adherence of the electrodes below the breast due to abdominal fat and sweat were likely to be the most pertinent issues and not

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easily avoidable. Participants of the RCT were therefore advised to wear the Actiheart above the breast unless they expressed concerns about its visibility, in which case they were given the option having it fitted below the breast.

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CHAPTER THREE

3. A RANDOMISED CONTROLLED TRIAL TO INVESTIGATE THE EFFECTIVENESS OF AN EXERCISE INTERVENTION IN THE TREATMENT OF POSTNATAL DEPRESSION

3.1

Introduction

In chapter one of this thesis, the academic background of this research was

discussed including the definitions, symptomatology, aetiology and epidemiology of postnatal depression. The current evidence base for the use of exercise in the treatment of depression in general adult populations, postnatal populations and postnatal women at risk of depression was described. As previously noted, the most recent systematic review of exercise and PND found that exercise may be an

effective treatment for PND (101). However, the evidence base in this field was found to be small, with only five published RCTs (11, 13-15, 80) encompassing a total study population of 238 participants. It was concluded that larger studies with sufficient post-intervention follow up conducted in clinically depressed populations were necessary. From studying the research postdating this review, it became evident that further research of high methodological quality was required. In particular, studies using objective measures of physical activity and a wide range of psychological outcome measures would be beneficial to the evidence in the field of exercise and PND. An RCT was therefore conducted to investigate the effectiveness of exercise as a treatment for PND and is reported in the present chapter.

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3.2

Background

There is a substantial body of evidence suggesting the effectiveness of exercise in reducing depressive symptoms in the general population (28). A recent Cochrane review of 35 trials (1356 participants) comparing exercise interventions with control or no treatment groups found a moderate effect size (SMD) for depression of -0.62 (95% CI: -0.81 to -0.42) (28). Exercise is currently also recommended to depressed mothers in the postnatal period by NICE (4) and the American Psychological

Association (174). These guidelines are, however, based on a limited number of trials with non-clinical populations (a diagnosis of depression not being required).

Research into the benefits of exercise for depression in the general population has suggested a range of other psychosocial factors that may be beneficially affected by exercise. These factors have been explored as secondary outcomes in this RCT. Discussion around the selection of secondary outcomes is provided below.