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Among Australians aged over 60 years, 55% of men and 61% of women are not sufficiently active to maintain general health.⁶ Encouragingly, a Western Australian survey found that 93% of general practitioners (GPs) reported asking about physical activity when a patient presented with a condition that might benefit from exercise, and 50% asked new patients about current physical activity patterns.⁷ However, GPs comment on a lack of skill in assessing and guiding activity and a lack of guidelines.⁸ Although many believe referral to a qualified fitness professional is desirable, fewer than 15% make these referrals.⁹

Previous studies of interventions to increase provision of advice and patients' physical activity in primary care have had mixed results and are of varying methodological quality.¹⁰ To reduce the demand on GPs, several groups have examined the effectiveness of advice from practice staff. Results of advice from a health visitor were initially favourable but were not sustained,¹¹ while advice from practice nurses produced no increases in objectively measured¹² or self-reported¹³ exercise levels in the short term.

Therefore, we designed a properly powered study to determine the effectiveness of individualised advice from an exercise specialist in a general practice setting on changing physical activity levels and cardiovascular risk factors at 12-month follow-up.

Exclusion criteria included a cerebrovascular or ischaemic cardiac event in the previous six months, malignancy or other life-threatening disease, inability to comply with the requirements of the study, a condition for which physical activity was contraindicated, use of β-blocker medication, and regular physical activity, leaving 351 people eligible.

These 351 were invited to attend a baseline appointment at which they signed a consent form and were randomly allocated to the intervention or control groups using sealed opaque envelopes. They also answered a written questionnaire about current physical activity levels, intention-to-exercise,¹⁵ quality of life (assessed by the Short Form 36¹⁶) and demographic information. Blood pressure, body weight and height were measured, and a blood sample was taken for lipid studies.

The intervention group received individualised advice about the benefits of physical activity and a pamphlet containing a plan for physical activity for the next three months. This plan, based on current position statements,^17,18 involved aerobic activities at moderate intensity for a minimum of three sessions per week for at least 20 minutes per session, with self-monitoring of heart rate.

The exercise plan, potential barriers to exercise and strategies to overcome these were discussed. The focus was on incorporating physical activity into the individual's usual activities and on increasing "self-efficacy" (belief in one's ability to perform the activity) by recommending a preferred, familiar activity and setting modest targets for the first three months. These targets were to be progressively increased, depending on progress, enthusiasm and health.

The control group received a pamphlet promoting good nutrition for older adults, which was discussed for 20 minutes.

At three and six months, all participants were mailed a follow-up questionnaire to be returned in a postage paid envelope (control participants) or at an interview (intervention participants). This interview was arranged by telephone, and intervention participants were encouraged to attend whatever their adherence to the exercise plan. Participants were also asked to complete a seven-day physical activity log as a prompt for discussion, which included physical activity levels and benefits, reasons for success or failure, injuries, heart-rate monitoring and changes to the plan.

At 12 months, all participants were invited to a follow-up interview, at which they completed a questionnaire, and clinical characteristics (except height) were remeasured.

Energy expenditure was measured for 59 participants (31 intervention and 28 control participants) over four days (two weekends and two weekdays) using a Caltrac portable, vertical accelerometer.¹⁹ These 59 were recruited by telephoning randomly selected participants until six volunteers per week were obtained (a total of 88 were telephoned).

Assumptions for parametric analysis were investigated. Repeated-measures analyses of variance were used to examine data for physical activity and five quality-of-life scores, using time as the within-subject variable, and time, intervention and sex as the between-subject variables. As data for three quality-of-life scales (roles physical and emotional and social functioning) were non-continuous and skewed, they were dichotomised (score of 100 = 0, score < 100 = 1) and then analysed with generalised estimating equations -- an extension of generalised linear models -- to examine time, intervention and sex interactions.²⁰ Twelve-month changes in clinical characteristics, quality-of-life and accelerometer results were analysed with Student's t tests (independent samples). Intention-to-exercise data were analysed with ² statistics. All data were analysed on an intention-to-treat basis. In the event of missing responses, data were entered at the previous follow-up, thereby assuming no change.

Three- and six-month follow-up questionnaires were returned by 274 (92%) and 269 (90%) participants, respectively, while 264 (88%) attended the 12-month follow-up interview (123 in the intervention and 141 in the control group). Of the 35 who did not attend, two had died, six were on holidays, seven were ill, and 20 were not interested. There were no statistically significant differences in baseline clinical and sociodemographic measures between participants who attended the 12-month follow-up interview and those who did not.

Energy expenditure data were available for 59 participants who wore an accelerometer (31 intervention and 28 control participants). The intervention and control groups did not differ significantly in any measured parameter of energy expenditure -- total per day, per day as a percentage of total energy expenditure, during activity per day, or during activity per kg body weight.

At all follow-ups, there were significant differences between the intervention and control groups for change in intention to exercise (P < 0.001). At 12-month follow-up, more intervention than control participants increased their intention to exercise (Box 3).

Quality-of-life scores decreased between baseline and 12-month follow-up in both the intervention and control groups. These score decreases were significant in both groups for bodily pain (P = 0.001), general health (P < 0.001), physical functioning (P < 0.001), vitality (P = 0.04) and role physical (odds ratio [OR], 1.80; 95% CI, 1.33-2.43).

Women in the intervention group had significantly greater score decreases than women in the control group for the scales role emotional (P = 0.02), role physical (P = 0.04) and social functioning (P = 0.04). In addition, women reported worse scores at 12-month follow-up than men for bodily pain (P = 0.02), mental health (P = 0.03), physical functioning (P = 0.04) and vitality (P = 0.01), and were 1.5 times more likely to report some difficulty with role physical (OR, 1.43; 95% CI, 1.03-1.99) and social functioning (OR 1.53; 95% CI, 1.06-2.21).

However, our study differs from most others in that it had a large number of participants and high retention rate (88% at 12 months), and calculated results on an intention-to-treat basis. The high retention rate possibly resulted from participants' strong association with their GPs, who were aware and possibly encouraging of their participation, and the fact that all visits were conducted at the GPs' practices. The success of the intervention may be attributed to the enthusiastic volunteer population, who, while sedentary, were keen to start regular activity. Another possible contributor was the strong emphasis on walking as the preferred activity. The physical activity advice had the characteristics of successful physical activity interventions -- a home-based program, comprising unsupervised, informal exercise (generally walking), of moderate intensity and comparatively low frequency (which is associated with better maintenance), as well as frequent professional contact.²²

The major limitation of this study was its reliance on self-report, as patients over 65 years tend to overestimate their physical activity.¹² The number of participants and limited resources precluded general use of more objective measures of physical activity or fitness. Objective measurements of energy expenditure by accelerometer in 59 volunteers did not detect a difference between the control and intervention groups, possibly because of the small sample size. Other possible reasons are that people in each group who had established regular physical activity volunteered preferentially for accelerometer measurement, or that the self-reported increase in physical activity in the intervention group was not real.

We were also unable to detect any differences between the intervention and control groups in cardiovascular risk factors after 12 months. This is consistent with results of others. For example, patients referred by their GPs to a local leisure centre had increased self-reported physical activity after 37 weeks, but no changes in systolic or diastolic blood pressures or body mass index.²³ In our study, the increase in self-reported physical activity in the intervention group was possibly not large enough to increase physical fitness. Previous investigators have shown that cardiovascular risk factors are more strongly related to physical fitness than to physical activity,^4,5 and that, in individuals with low levels of fitness, increased physical activity without a change in fitness does not modify cardiovascular risk factors.²⁴ Further, although the difference in physical activity between the intervention and control groups reached statistical significance, it was modest in absolute terms. Finally, all participants remained under the usual care of their GPs, who were free to initiate or cease prescribing medications that might modify cardiovascular risk factors.

We found declines in quality of life from baseline to 12 months in both groups, with the greatest change in the first three months. We hypothesise that quality of life was more accurately reported at three months than at baseline, when scores were much higher than the Australian norms for the participants' age. It is possible that participants were initially keen to present themselves as healthy in all respects or that they were expressing high hopes for the study.

In conclusion, this study showed that, for a specific population of general practice patients, providing physical activity advice three-monthly for six months resulted in increases to both self-reported physical activity and intention to exercise, which were maintained at 12-month follow-up. Further research in primary care is needed to determine whether these changes apply to other groups and whether they confer significant health benefits.

Conflict of interest: None.

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