Benefits and risks of physical activity and current physical activity guidelines
What are the benefits of physical activity for adults and older adults?
Physical activity (PA) leads to reduced mortality, a reduced risk of > 20 diseases and conditions, and improved function, quality of life and emotional well-being.1 Physical inactivity is the fourth leading risk factor for global mortality;2 in 2008, it was estimated to have caused 9% of premature mortality and 5.3 million deaths worldwide.3 Physical inactivity is also a major cost burden on health services.1,4,5
What are the current physical activity guidelines and who is achieving them?
Adults and older adults are advised to be active daily and, for health benefits, should achieve at least 150 minutes (2.5 hours) weekly of at least moderate-intensity activity [moderate to vigorous PA (MVPA)] or 75 minutes of vigorous-intensity PA, or an equivalent combination, achieved in bouts of at least 10 minutes’ duration.1,2 Muscle-strengthening activities are also recommended on at least 2 days weekly,1,2 but are not part of our intervention, which is focused on increasing walking. One effective way to achieve the aerobic PA recommendations is by undertaking 30 minutes of moderate-intensity PA on at least 5 days weekly.1,6,7 Regular walking is the most common PA of adults and older adults, and walking at a moderate pace (3 miles or 5 km per hour) qualifies as moderate-intensity PA.8 Time spent being sedentary for extended periods should also be minimised, as this is an independent disease risk factor,1 which increases steeply with age from 45 years.9 There is an increasing awareness that as a dose–response relationship exists for PA and health benefits, getting inactive people to do a little more PA is also important, rather than just relying on trying to achieve PA recommendations.10,11 Emphasising that the 30 minutes can be built up from 10-minute bouts is an important message for older adults and those with disabilities, enabling them to increase their MVPA gradually. Among adults in England aged ≥ 19 years, 66% of men and 56% of women self-reported meeting the recommended PA levels, whereas only 58% of men and 52% of women aged 60–74 years did so.12 Lower socioeconomic groups9 and Indian, Pakistani, Bangladeshi and Chinese ethnic groups are significantly less likely to report meeting the recommended PA levels, whereas the activity levels of other ethnic groups (black Caribbean, black African and Irish) are similar to that of the general population.13 Over one-third of adults worldwide are insufficiently active, but there is large geographical variation.10,14 However, PA, including walking, is very unreliably recalled, so surveys overestimate PA levels.15 Objective accelerometry found that only 5% of men and 4% of women aged 35–64 years and 5% of men and 0% of women aged ≥ 65 years achieved the recommended PA levels, which is a fraction of those who self-report achieving them.9
What are the risks from increasing physical activity?
The risks from a sedentary lifestyle far exceed the risks from regular PA.6,16,17 Moderate-intensity PA carries a low injury risk,18 mainly musculoskeletal injury or falls.19 Walking is very low risk, ‘a near perfect exercise’.8 Screening participants for contraindications before participating in light- to moderate-intensity PA programmes is no longer advocated.6,20 An important safety feature of our study is that individualised goals can be set from the participant’s own baseline, in line with the advice that older adults in particular should start with low-intensity PA and increase the intensity gradually: the ‘start low and go slow’ approach.16,17 This worked well with our previous PA trial in older adults, which employed a similar approach and showed no increase in adverse events (AEs).21
Strategies for increasing physical activity
How can adults and older adults increase their physical activity levels?
A systematic review of PA interventions reported moderately positive short-term effects, but the findings were limited by mainly unreliable self-report measures in motivated volunteers.22 This review has recently been updated by three complementary Cochrane reviews assessing (1) face-to-face PA interventions,23 (2) remote (including postal and telephone) and web 2.0 interventions24 and (3) a direct comparison of these two approaches.23 Evidence supports the effectiveness of both face-to-face interventions and remote or web 2.0 interventions for promoting PA. However, the reviewers called for future studies to provide greater detail of the components of face-to-face interventions and to assess the impact on quality of life, AEs and economic data,23 and to include participants from varying socioeconomic and ethnic groups.24 Only one study25 met the review criteria to compare face-to-face interventions with remote or web 2.0 interventions (many trials were excluded as a result of having less than 1 year’s follow-up data or an inadequate control group); this study showed no effect on cardiorespiratory fitness25 and there were no reported data for PA, quality of life or cost-effectiveness.23 The review concluded that there was insufficient evidence to assess whether face-to-face interventions or remote and web 2.0 approaches are more effective at promoting PA, and called for more high-quality comparative studies.23 None of the studies included in the reviews provided objective PA measurement.23,24 Other studies have concluded that exercise programmes in diverse populations can promote short- to medium-term increases in PA when interventions are based on health behaviour theoretical constructs, individually tailored with personalised activity goals and using behavioural strategies.26,27 A critical review and a best-practice statement on older people’s PA interventions advised home-based rather than gym-based programmes, and behavioural strategies (e.g. goal-setting, self-monitoring, self-efficacy, support, relapse prevention training), rather than health education alone.17,27 National Institute for Health and Care Excellence (NICE)’s guidance concluded that no particular behaviour change model was superior and that training should focus on generic competencies and skills, rather than on specific models.28 More recent complementary NICE guidance specifically recommended that goals, planning, feedback and monitoring techniques should be included in behaviour change interventions.29 Starting low, but gradually increasing to moderate intensity is promoted as best practice, with advice to incorporate interventions into the daily routine (e.g. walking).17 A recent systematic review of walking interventions concluded that interventions tailored to people’s needs, targeted at the most sedentary people and delivered at the level of the individual or household, can be effective, although evidence directly comparing interventions targeted at individuals, couples or households was lacking.30
Are pedometers helpful?
Pedometers are small, cheap devices, worn at the hip, providing direct step count feedback. A systematic review (of 26 studies) found that pedometers increased steps per day by 2491 steps [95% confidence interval (CI) 1098 to 3885 steps] and PA levels by 27%, with significant reductions in body mass index (BMI) and blood pressure.31 A second review (of 32 studies) found an average increase of 2000 steps per day.32 Step count goals and diaries were key factors.31,32 Several limitations were recognised: study sizes were small and long-term effects were undetermined; many studies included several components (e.g. pedometer and support), so independent effects were difficult to establish; and the inclusion of older people and men was limited.31,32 Recent studies have addressed some of these limitations. A pedometer plus behaviour change intervention increased PA at 3 months, but not at 6 months, in 210 older women, with pedometers providing no additional benefit.33 Two trials in high-risk groups showed sustained step count increases at 12 months.34,35 A recent study of 298 older adults found a significant increase in both step counts and time in MVPA at 3 months and 12 months from a practice nurse-delivered pedometer-based walking intervention, but did not separate out pedometer- and nurse support-related effects.21 NICE recently updated its advice from advising the use of pedometers only as part of research36 to advising their use as part of packages, including support to set realistic goals, monitoring and feedback.37
How do step count goals relate to physical activity recommendations?
Step count goals lead to more effective interventions, but no specific approach to goal-setting is favoured.28 Goals are based on a fixed target (e.g. 10,000 steps per day)38,39 or on advising incremental increases from the baseline as a percentage (5% per week,40 10% biweekly41 or 20% monthly33) or on a fixed number of extra steps. Those advocating a fixed number of extra daily steps have developed step-based guidelines to fit with existing evidence-based guidelines with an emphasis on 30 minutes of MVPA on ≥ 5 days weekly.42 Despite individual variation, moderate-intensity walking appears to be approximately equal to at least 100 steps per minute.42,43 Multiplied by 30 minutes, this produces a minimum of 3000 steps per day, to be done over and above habitual activity, which is the ‘3000 in 30’ message.43 Several studies have advocated adding in 3000 steps per day on most days weekly, either from the beginning34 or by increasing incrementally (initially an extra 1500 steps per day and increasing),44,45 or by increasing by 500 steps per day biweekly.35 Studies that advised adding 3000 steps per day from the baseline produced significant improvements in step counts at 3 months and two measured outcomes at 12 months, and showed sustained improvements in step counts,34,35 waist circumference34 and fasting glucose levels,35 but no sustained improvements to date in MVPA levels. Although there is no evidence at present to inform a moderate-intensity cadence (steps per minute) in older adults, Tudor-Locke et al.46 advocate using the adult cadence of 100 steps per minute in older adults (while recognising that this may be unobtainable for some individuals) and advising that the 30 minutes can be broken down into bouts of at least 10 minutes. This model was used in a primary care walking intervention in 41 older people, which found significant step count increases from baseline to week 12, which were maintained at week 24.47,48
Could accelerometers be useful in a pedometer-based walking intervention?
Accelerometers are small activity monitors worn like pedometers, but are more expensive; however, they are able to provide a time-stamped record of PA frequency (step counts) and intensity (activity counts). They require computer analysis, function as blinded pedometers in objectively measuring baseline and outcome data, and provide objective data on time spent in different PA intensities, including time spent in MVPA and time spent being sedentary, two important public health outcomes. Pedometer studies without accelerometers have relied on self-reported measures of these outcomes. Accelerometers are valid and acceptable to adults9,49 and older adults.9,21,50–53 Although both instruments measure step count and are highly correlated,50 pedometers usually record lower step counts, and accelerometers cannot reliably be substituted for pedometers at an individual level.54 Thus, although we used the accelerometer to measure outcomes, including step count, MVPA and sedentary time, we used the blinded pedometer, worn simultaneously at baseline, to set individual step count targets.
Are pedometers cost-effective?
There is limited knowledge on the cost-effectiveness of pedometer-based interventions in the UK. Recent systematic reviews that considered the economic outcomes of pedometer-based interventions found no evidence,55,56 partly because of an insufficient number of data.57 However, a recent study assessed the cost-effectiveness of giving an individualised walking programme and pedometer with or without a PA consultation alongside a community-based trial of 79 people.58 The incremental cost-effectiveness ratios (ICERs) per persons achieving an additional 15,000 steps per week were £591 and £92 with and without the consultation, respectively. However, even with this highly selected sample, no data on quality of life were collected, and the impacts on long-term outcomes were not estimated.
What is the role of primary care in promoting physical activity?
Primary care centres (general practices) in the UK provide health care and health promotion, free at the point of access, to a registered list of local patients (for many of whom PA will be of benefit), using disease registers to provide annual or more frequent chronic disease reviews via a multidisciplinary health-care team providing continuity of care. NICE guidance found that brief interventions in primary care are cost-effective, and it therefore recommends that all primary care practitioners should take the opportunity to identify inactive adults and provide advice on increasing PA levels.36 New 5-yearly NHS health checks include adults aged 40–74 years and incorporate advice on increasing PA, often from primary care nurses.59 Primary care nurses are effective at increasing PA, particularly walking, in this age group.60 Not only can PA advice through consultation with health professionals be individually tailored61 and have more impact than other PA advice,62 but this is particularly the case for older adults,63 especially given the uncertainty about the effectiveness of exercise referral schemes from primary care.64 Exercise-prescribing guidance in primary care reinforces the importance of follow-up to chart progress, set goals, solve problems, and identify and use social support;65 this will be an important feature of the nurse PA consultations in this trial. Evaluation of the UK Step-O-Metre programme, delivering pedometers through primary care, showed self-reported PA increases, but advised investigation with a randomised controlled trial (RCT) design.44 Two trials, both in older primary care patients, have assessed the effectiveness of pedometers plus primary care PA consultations; one small trial (n = 41) showed a significant effect on step counts at 3 months, which was maintained at 6 months,47,48 and the other was our recent Pedometer Accelerometer Evaluation-LIFT (PACE-LIFT) trial21 (n = 298), which showed differences in both step counts and time in MVPA in bouts of at least 10 minutes, at 3 and 12 months for the nurse intervention compared with the control group. Neither trial separated out pedometer effects from the support provided.21,47,48
Theoretical base, piloting and preparatory work to develop the intervention
The pedometer-based intervention is based on work cited above,31,32 showing that pedometers can increase step counts and PA intensity.31,32 It extends current understanding by also including older adults and men, having a 12-month follow-up and ensuring that the pedometer and support components could be evaluated separately. The patient handbook, diary (both available on the journals library website: www.journalslibrary.nihr.ac.uk/programmes/hta/103202/#/) and practice nurse PA consultations use behaviour change techniques (BCTs; e.g. goal-setting, self-monitoring, feedback, boosting motivation, encouraging social support, addressing barriers or relapse anticipation). These techniques have been successfully used by non-specialists in primary care after brief training,66 and are emphasised in the Improving Health: Changing Behaviour: NHS Health Trainer Handbook,67 based on evidence from a range of psychological methods and intended for NHS behaviour change programmes, with local adaptation.67 They also include techniques specifically recommended to be included in more recent NICE guidance (goals, planning, feedback and monitoring).29 We adapted the Improving Health: Changing Behaviour: NHS Health Trainer Handbook67 for use in this trial into Pedometer And Consultation Evaluation-UP (PACE-UP) nurse and patient handbooks, to focus specifically on PA using pedometers. The BCTs were classified in accordance with the refined taxonomy of BCTs for PA interventions by Michie et al.68 Diary recording of pedometer step counts provides clear material for PA goal-setting, self-monitoring and feedback, and should fit well with this approach. We have adopted the approach used by others44,45 of advocating adding in 3000 steps per day to an individual’s baseline on most days weekly in an incremental manner, and of advising on gradually increasing PA intensity to achieve more time in MVPA, with the message that 3000 steps in 30 minutes will help people to achieve PA guidelines.43 Relevant pilot and preparatory work includes observational work using pedometers and accelerometers in primary care53 and a successful trial with older primary care patients developing the PA consultations and pedometer-based walking intervention (the PACE-LIFT trial; ISRCTN4212256121,69). The PACE-LIFT trial demonstrated that tailored support from practice nurse PA consultations combined with a pedometer-based walking programme (plus accelerometer feedback on PA intensity) led to an increase in both step counts and time in MVPA compared with the control group at both 3 and 12 months in 60- to 75-year-old primary care patients. The trial was limited in terms of both ethnic and socioeconomic diversity, has not yet published on sedentary time or cost-effectiveness and, as mentioned, was unable to separate out the effects of the pedometer (and accelerometer feedback) from the effects of nurse support.21
Rationale for research
The PACE-UP trial aimed to fill the gaps in the current evidence base by evaluating the effect of a pedometer-based walking intervention, with and without additional nurse PA consultations in a population-based, primary care sample of inactive adults and older adults. The initial trial included follow-up to 1 year and aimed to ensure that adequate numbers of men, older adults and individuals from diverse socioeconomic and ethnic backgrounds were included. It also enabled the effectiveness of taking part as an individual or as a couple to be estimated. The intervention used step goals and diaries, and the PA consultations and patient handbook were based on BCTs, such as those used in the Improving Health: Changing Behaviour: NHS Health Trainer Handbook.67 To objectively test the effectiveness of the intervention on important public health outcomes, such as time spent in MVPA and time spent being sedentary, PA outcomes were assessed by accelerometry. Anonymised practice demographic data were available for all those invited to participate, enabling the investigation of inequalities in trial participation. Qualitative evaluations were also needed to explore the reasons for trial non-participation, the acceptability of the intervention to both participants and practice nurses and the barriers to, and facilitators of, the intervention. An economic evaluation was performed alongside the trial and was also used to inform long-term cost-effectiveness.