To our knowledge, this is the first study to investigate perioperative physical activity levels in men having radical prostatectomy, and to investigate the relationships between both objectively measured physical activity levels and PPUI. We found that patients receiving a physiotherapist-guided PFMT and physical activity intervention had significantly reduced physical activity levels at 3 weeks postoperatively, but physical activity levels had recovered to baseline (preintervention) levels at 6 weeks postoperatively. There was no significant effect of preoperative physical activity levels on PPUI, nor were there significant correlations between postoperative physical activity levels and severity of PPUI. Finally, surgical group (ORP vs RALP) did not significantly affect the severity of early PPUI, or the course of recovery of postoperative physical activity.
There are limited published data against which to compare our physical activity data. Baseline physical activity as measured with the IPAQ (median 3276 MET.min/week) was similar to that reported in a 12-country (including Australia) study of the IPAQ in healthy adults (median 3699 MET.min/week) . It is suggested that subjective questionnaires, such as the IPAQ, overestimate physical activity levels ; as such, from the week before surgery we also used a validated physical activity monitor to objectively measure physical activity levels. Objectively measured physical activity durations from the week before surgery to six weeks postoperatively ranged from 42-66% of those reported in a study of healthy European men (also using the SenseWear Pro3 Armband) .
The overall physical activity levels of the cohort must be taken into account when considering the non-relationship between preoperative physical activity levels and PPUI in the current study. The one previously published study reporting an association between inactivity/obesity and PPUI described activity dichotomously (active vs non-active) using a low threshold (</> 1 hour of exercise/week) . By comparison, mean physical activity duration for our cohort in the week before surgery was 15 (7) hours, and no patient did <4 hours of physical activity per week. It is conceivable that a threshold level of preoperative physical activity is continence-protective, and that, by providing our cohort with a physical activity intervention, we ‘lifted’ all patients above that threshold.
The absence of a relationship between postoperative physical activity levels and PPUI is of interest. An a priori hypothesis that patients with more severe PPUI might curtail their postoperative physical activity was not supported. Nor did we find evidence that patients engaging in more postoperative physical activity experienced worse PPUI. The clinical implication is that patients might be encouraged to increase their physical activity postoperatively towards (or above) baseline levels, without fear of worsening/delaying return to continence.
The urinary incontinence outcomes support that our cohort had low overall severity of PPUI; this too might have limited the power of the current study to demonstrate significant relationships between perioperative physical activity levels and PPUI. The mode of surgical and perioperative management in the current study (i.e. using a predominantly nerve-sparing approach, all patients receiving preoperative PFMT) has been shown to optimise postprostatectomy continence outcomes [3–5, 9]. 24HPTs of 42 ± 59 g at 3 weeks and 29 ± 40 g at 6 weeks postoperatively are at the low end of those reported at similar time-points in trials of PFMT among patients having ORP (median 28–249 g) [22, 23], and less than that reported in a cohort of patients receiving RALP with rhabdosphincter reconstruction (184 g at 6 weeks) . Similarly, ICIQs of 8 (5) at 3 weeks and 6 (4) at 6 weeks postoperatively are considerably lower than those reported even in a ‘successful’ randomized trial of preoperative PFMT (15 at 4 weeks postoperatively) .
That surgical group did not affect the course of postoperative physical activity was surprising. A key proposed benefit of RALP is that, given the smaller incisions required, patients experience less pain, and ‘faster recovery and return to normal activities’ . Indeed, randomized trials of ORP vs RALP have demonstrated that patients having RALP take less sick leave , and have a faster return to baseline quality of life . There are, however inherent difficulties with blinding patients and health practitioners in such trials, and the possibility that that recovery might have been influenced by preconceived patient/practitioner expectations in those studies cannot be discounted. Our results suggest that early return to baseline physical activity levels is feasible regardless of surgical group/approach, given perioperative physiotherapy with a focus on physical activity. Specific surgeon-proscribed activities, e.g. heavy lifting, may still be contraindicated.
Limitations and strengths of the study
Patients were not randomized to physical activity prescription, therefore the explicit effect of physical activity prescription on PPUI and postoperative physical activity levels cannot be determined. Nor were patients randomized to surgical approach. Physiotherapy including physical activity prescription has been a routine component of the perioperative care pathway for men in our clinical setting, and ethical concerns precluded its withdrawal.
A second limitation of the study is the small sample size, which reduced the power of the study to find significant between-group differences in PPUI and postoperative physical activity levels. Broadening study inclusion criteria to enable recruitment of more participants, and with a greater range of physical activity levels and urinary incontinence outcomes, is perhaps warranted in future studies. The relatively short follow-up period for the study (6 weeks) is not seen as major limitation, as it is uncommon for patients to attend physiotherapy treatment beyond this in our clinical setting, and the benefits of physiotherapy/PFMT for PPUI reduce in the longer term .
A strength of the study is the use of both subjective and objective measures of physical activity levels and PPUI. Substantial discrepancies have been shown between subjective and objective measures of PPUI in patients after radical prostatectomy (patients under-reporting PPUI);  as with subjective overestimation of physical activity levels these discrepancies may relate to a social desirability bias. Unfortunately, we were unable to obtain a baseline objective measure of physical activity, as preoperative physical activity prescription commenced on the day that patients were recruited to the study (the initial preoperative physiotherapy appointment).