Effectiveness of a supervised group-based walking program on physical, psychological and social outcomes among older adults: a randomised controlled trial protocol

Abstract

Introduction

To minimise adverse health events among older adults, physical activity (PA) is considered one of the most fundamental and effective forms of lifestyle. Therefore, an urgent effort to promote a physically active lifestyle among our older adults is needed, in which walking could be a better choice, especially for mass promotion. Besides, the types of PA interventions were also shown to affect their effectiveness on older adults’ psychosocial outcomes. Hence, the overall aim of the project is to examine the effectiveness of supervised group-based walking intervention by comparing it with unsupervised group-based walking and unsupervised individual-based walking interventions on improving physical, psychological and social outcomes among older adults in Hong Kong.

Methods and analysis

The research will conduct a four-group (supervised group-based, unsupervised group-based walking, unsupervised individual-based, control group), double-blind, randomised control trial, targeting 184 older adults in Hong Kong. The primary outcomes will be measured by participants’ changes in resting heart rates, body compositions, resting blood pressures, walking performance, loneliness, perceived social support and PA enjoyment. The results will be analysed using repeated analysis of variance and one-way analysis of covariance, as well as by conducting in-depth interviews with selected participants. Also, the outcomes of the research will be used as references for designing an effective walking operation manual for promoting healthy ageing among older adults in the community.

Ethics and dissemination

The current study involves human participants, and the research protocol has been approved by the research ethics committee at Hong Kong Baptist University (Ref: R2022-2023-0013). All participants will be provided with written informed consent to participate. The outcomes of the intervention protocol will be disseminated through manuscript publications.

Trial registration number

The trial is registered at the ClinicalTrials.gov PRS (Trial ID: NCT05907252; date of first posted: 16 June 2023).

STRENGTHS AND LIMITATIONS OF THIS STUDY.

• Group-based format: examines the effectiveness of a group-based walking programme led by a professional supervisor, addressing limitations of previous buddysystem designs, which are difficult to standardise.

• Standardised delivery: involving a trained supervisor helps standardise intervention delivery and control for individual differences/skills that may confound two-person buddy systems.

• Social aspects: evaluates physical impacts and potential social benefits of a group-based programme by assessing outcomes such as loneliness, social inclusion and support—areas not consistently demonstrated in previous meta-analyses.

• Walking as a sole activity: walking may not be sufficiently engaging as a lone exercise activity over the long term for older adults. Reliance solely on walking risks higher attrition compared with programmes with more varied activity types.

• Practical challenges of group-based supervision: outdoor location also introduces variability due to weather conditions that could impact consistency and adherence.

Introduction

According to the WHO,¹ the number of people over 60 years old in the globe is increasing, and it is projected that this number will increase by 40% in 2030 and by 110% by 2050. In Hong Kong, based on the statistics provided by the Office of Government Economist (2019), the proportion percentage growth of people aged 65 years or above will almost double to reach 31.9% in 2038.

Due to the reduced physical function and mobility caused by ageing, most older adults are highly committed to a sedentary lifestyle and are the most physically inactive population within a community.² The research suggested that a longer duration of inactive or sedentary lifestyle could trigger various physical-related diseases and mental health problems, such as overweight or obesity, diabetes, bone and cardiovascular disorders and lower level of health-related quality of life (HRQoL),³ depression⁴ and loneliness. In particular, a longitudinal study in Hong Kong⁵ revealed that the physical and mental health of older adults has declined in the past 10 years. The study also indicated a reciprocal relationship between physical health and mental health, while mental health was shown to be the most interference factor due to the subsequent changes in physical health. Physical activity (PA) is considered one of the most fundamental and effective forms of lifestyle intervention.^{1 6} The local studies revealed that PA was significantly associated with psychological well-being, including self-esteem, satisfaction and quality of life among Hong Kong older adults.^{7 8} Walking is one of the most popular physical activities for older adults because it is less reliant on the environment and equipment than other forms of exercise, making it more sustainable. Furthermore, walking is considered an essential component of outdoor mobility which could be easily transformed into a transport tool to replace driving or public transport. It was suggested that individuals should complete 8000 to 10 000 steps per day to achieve better physical and mental health.⁹

A recent systematic review and meta-analysis¹⁰ concluded that nearly 43% of the research interventions on older adults were focused on strength, power and resistance training, 30% on mind–body exercises such as tai chi, qigong and yoga, while only 20% were on walking or mobility intervention. Although walking might be less popular than tai chi, walking was found to elicit almost 46% higher metabolic cost than tai chi¹¹ demonstrating as one of the most commonly recommended physical activities for older adults. Previous studies showed that regular walking could achieve better physical, functional and mental health among older adults, as well as lower mortality rate,¹² facilitate weight loss, higher mobility, prevent chronic diseases and risk of falling13,16 and generate positive psychological health, including vitality¹⁶ independency, life satisfaction, subjective well-being and quality of life.1315 17,19

Regarding the effectiveness of interventions, a systematic review and meta-analysis stated that PA alone interventions showed inconsistent psychosocial outcomes, including social inclusion and loneliness, among older adults.²⁰ Yet, a previous study reported that group-based physical activities showed greater contributions than individual-based physical activities on physical, psychological and social well-being among older adults.²¹ Subsequent studies on group-based intervention also showed improvement in social inclusion, loneliness and social interaction along with the social support structures involved in a group activity.22,24 Moreover, a meta-analysis found that walking in a group could facilitate individuals’ efficacy in walking, thus significantly promoting a higher level of PA.²⁵ Similar results were also revealed in our research team’s previous qualitative study, suggesting that older adults would be better motivated to walk if they were assigned to a group and involved with social interaction. The research team’s other research project also found better walking habits under companionships, social cohesion, encouragement and role models among the elderly participants. Furthermore, studies^{10 21 26} indicated that group-based physical activities with professional supervision showed benefits to older adults, especially in encouraging acceptable adaptations to perform various exercises or physical activities related to bones, muscles and cardiovascular system, provided that physical activities can be performed either in group based or individual based. A recent meta-analysis on older adults’ exercise interventions¹⁰ found that the findings from group exercise intervention trials were contradictory. Further studies were encouraged to examine the disparities between groups and individual exercise intervention, as well as the impact of professional delivery and significant others on the results of exercise intervention.

When reviewing the walking-related programmes in Hong Kong, the research team found two local walking programmes named ‘QualiWalk’ (2013) and ‘Walk the City for Active Ageing’ (2019). Both programmes implement a buddy-and-peer leader system by training young-olds as the programme ambassadors, equipping them with knowledge of appropriate walking postures and leadership skills, with the aim of assisting walking groups for older adults. Previous studies^{27 28} revealed that the buddy system with peer leadership could serve as a role model for the participants, thus providing better connection and empathy towards individuals of similar age compared with a non-peer leader. The buddy system would be a stronger motivation among the participants to adopt regular walking habits. However, the buddy system or peer leader system has limitations in terms of cost-effectiveness. Researchers may find it difficult to control confounding factors created by the buddy or leader, such as individual differences, communication and management skills when delivering the intervention.²⁹ Hence, this might cause contrasting effects on promoting PA as well as on the outcomes of the intervention.³⁰ Additionally, the ‘QualiWalk’ programme did not provide regularly updated information, and the effectiveness of the programme was not clear to the public. Hence, it was difficult to reach those inactive older adults in the community, as well as failed to provide a scientific, documented and sustainable walking programme for older adults in Hong Kong.

In order to advocate and achieve a Healthy Life Expectancy in 2023, the WHO recently released ‘Decade of Healthy Ageing Baseline Report’,¹ aiming to promote healthy ageing through improving older adults' intrinsic capacity (both physical and mental capacities) and providing integrated care and services to respond to the needs of older adults. As referring to the integrated care and services mentioned in the WHO’s report, it is believed that these services would be less likely achieved without involving professional guidance and a social support environment. Also, from the literature review, the previous studies have shown support for further studies adopting professional supervision and group-based intervention approaches. With the above significant references and recommendations, the research team has a strong justification for proposing the current study to examine whether a professionally supervised group-based walking programme is more effective than unsupervised group-based as well as unsupervised individual-based walking programmes in improving physical, psychological and social outcomes among the older adults in Hong Kong. The findings of this randomised controlled trial (RCT) intervention study will shed light on the formats of the subsequent walking promotion programme for older adults in the community.

Aims and objectives

The overall aim is to examine the effectiveness of supervised group-based walking intervention by comparing it with unsupervised group-based walking and unsupervised individual-based walking interventions on improving physical, psychological and social outcomes among older adults in Hong Kong. The outcomes of the research will be used as references for designing an effective walking operation manual for promoting healthy ageing among older adults in the community.

Objective 1. To compare the differences of effects among supervised group-based, unsupervised group-based and unsupervised individual-based walking intervention programmes, as well as the control group (CG) on the primary outcomes, including physical health, walking performance, loneliness, perceived social support and PA enjoyment among older adults in Hong Kong.

Objective 2. To compare the differences of effects among supervised group-based, unsupervised group-based and unsupervised individual-based walking intervention programmes, as well as the CG on the secondary outcomes, including HRQoL and functional fitness among older adults in Hong Kong.

Methodology

Study design

The study will apply a four-group (three intervention groups and one CG), single-blinded and RCT to compare the effectiveness of supervised group-based, unsupervised group-based and unsupervised individual-based walking intervention programmes, as well as the CG on physical, psychological and social outcomes among the Chinese older adults in Hong Kong. There will be three time points for collecting data on the outcome measures, namely pretest (a week prior to commencement of the 18-week intervention), post-test (immediately after the 18-week intervention) and follow-up test (12 weeks after completion of the 18-week intervention).³¹ The research team’s most recent study^{32 33} found a weak significant effect even after conducting a 15-week walking intervention, despite previous research showing the significant effect of a 12-week walking intervention.³⁴ Thus, the current study proposes an 18-week walking intervention. In terms of the intervention design, the supervised group-based walking programme will involve certified walking trainers to offer the participants expert direction and supervision. On the other hand, research assistants will handle the administrative support for the unsupervised group-based and unsupervised individual-based walking programmes in order to guarantee attendance and overall safety, but they would not offer any professional guidance or supervision.

Sample size estimation

G*Power is used to determine the sample size. Based on the previous intervention studies, the most frequently reported effect size on physical health ranged from low (0.12) to moderate (0.35),¹⁰ an average effect size of 0.245 will be adopted for the current study. To ensure a power of 95% probability for detecting a treatment difference at a two-sided 5% level of significance, a sample size of 40 participants per group (total 160 for 4 groups) is expected. Also taking into account a 25% potential dropout rate, a sample size of 50 participants per group (total 200 for 4 groups) will be required in the current study.

Participants’ characteristics and recruitment

With support from the elderly centres in Hong Kong, the current study will recruit 200 older Chinese adults from the elderly community service centres using the convenience sampling method. There were 172 elderly community service centres in Hong Kong, while four centres will be used for recruitment to ensure the fulfilment of the three intervention groups and one CG. The inclusion criteria for the selection of participants include (1) chinese older adults aged 65 years or above; (2) capable of walking without an assistive device; (3) healthy and living independently in communities; (4) no cardiovascular or related diseases that prevent from intensive walking; (5) passing the Physical Activity Readiness Questionnaire (PAR-Q) screening or with physician’s advice on the readiness of participation in walking training; (6) with no diagnosed cognitive impairment (screened by the Abbreviated Mental Test³⁵); and (7) being physically inactive. During the recruitment process, potential participants’ ages, items in the PAR-Q test, and items in the Abbreviated Mental Test will be collected for characterisation.

Grouping and randomisation

In assigning the groups, the Consolidated Standards of Reporting Trials procedure (figure 1) will be followed.³⁶ The 200 selected participants who have signed consent letters will be randomly assigned to the four groups by a draw of lots, in a ratio of 1:1:1:1. The four groups will be (1) supervised group-based intervention (n=50), (2) unsupervised group-based intervention (n=50); (3) unsupervised individual-based intervention (n=50) and (4) CG (n=50). The intervention groups will receive an 18-week walking training in accordance with the intervention formats, whereas the CG will not receive walking training during the 18-week intervention. However, the CG will be provided walking training opportunities (in terms of resources, only unsupervised individual walking training will be offered) after the follow-up test (12 weeks after completion of the invention). This offer will be an incentive for the participants to stay in the CG until the completion of the project. Moreover, after the intervention programme and the follow-up test, participants from the 3 intervention groups (10 participants from each group will be randomly selected) will be invited to participate in the interviews.³⁷

Figure 1. Consolidated Standards of Reporting Trials diagram. The sample size, grouping process of participants and the timeline of pre, post and follow-up test of the intervention study.

Stage 1 (week 1 to week 2): basic walking practice

The intervention will be an 18-week walking programme, with three times per week on alternative days. Considering the social restriction and closure of sport and recreation facilities during the COVID-19 pandemic, older adults would be expected to have a decrease in PA participation but an increase in sedentary behaviour, thus leading to a reduction in exercise self-efficacy. Therefore, in order to motivate the older adults in re-engaging in active behaviours, as well as building up their confidence in participating in PA, all intervention groups will be given a 2-week basic walking practice with three sessions per week, 30–45 min per session and being led by a certified walking trainer. The walking practice will take reference from the exercise procedure recommended by the ‘Healthy Exercise for All Campaign’. The exercise procedure includes warm-up and stretching, walking and cooling down, walking aerobics for elderly fitness and 25-type joint aerobics.

Stage 2 (week 3 to week 18): main walking programme

On completion of the 2-week basic walking practice, participants will enter week 3 to week 18 main walking programme, in which the duration of each training session will increase to 45–70 min, depending on the levels of training. In the walking programmes, the progressive training principle will be adopted, using four levels as prescribed, in which weeks 3–6 are level 1; weeks 7–10 are level 2, weeks 11–14 are level 3, week 15–18 are level 4 (please refer to online supplemental table 1 for the details of the walking programme).38,42 The levels of progression could ensure the physically inactive participants to have sufficient time to equip with an appropriate base of fitness and familiar with the regular walking regime, as well as to prevent musculoskeletal injuries and overtraining. Also, the design of the training sessions will include the expected target of heart rates, the intensity and the expected amount of steps. Yet, the participants will be reminded to perform according to their own ability. The accumulated steps and the heart rate change within the target time period will be recorded by a wrist-worn Fitbit Inspire V.2 (Fitbit, 2020), which will be provided to the participants to keep track of their exercise intensity levels, including their heart rate changes in relation to their target heart rate zones, and the accumulated number of steps after each session. The Fitbit Inspire V.2 will be given to the participants at the beginning of the session and collected at the end of the session by RA for data inputting. In addition to progression, the training principle of individuality will also be applied to the participants doing the walking. The participants will be allowed to complete the targeted walking steps based on their own capability as reflected by the targeted heart rates as well as physical conditions during walking. Participants are free to take short breaks or withdraw from walking if they are uncomfortable doing it according to the schedule. Furthermore, in order to minimise the external influences caused by environmental settings, all the intervention groups will receive the training at the same venue. Certified walking trainers will be involved in the supervised group-based walking programme in order to provide professional guidance and supervision to the participants. The Physical Fitness Association of Hong Kong, China (PFA) will provide certified walking trainers who have completed the Quali-Walk Leader Certification. Any people who are aged 18 years or above and obtained ‘Physical Fitness Foundation Certificate’ from PFA are eligible to attend the course. The trainers should finish 12 hours lectures and practicum (including examination) to receive the certificate. The certificate validation is permanent, which trainers can work at governmental and non-governmental organisations or other related parties.⁴³ Whereas the non-supervised group-based and non-supervised individual-based walking programmes will be conducted by research assistants to ensure attendance and general safety, but without providing professional advice or supervision. In addition, the group-based walking programmes will be conducted in a fixed timeslot and the participants will be training together in a group. Participants in the individual-based walking programme will be given three timeslots to choose from in each training session. The choice will provide the participants with greater individuality and flexibility in conducting their walking training. On completion of the 18-week walking interventions, only data of the participants who have attended at least 70% of the training sessions will be included for analyses.

The control group

Participants in the CG will not be arranged to participate in any walking or PA intervention during the whole study period (the 18-week intervention and 12-week follow-up periods), but they will be asked to keep a daily log on their PA, use of medicines, illness and other health-related activities. Besides, the CG participants will be asked to report to the research resistant (RA) if a major change has occurred. The RA will also check the participants’ daily logs by telephone or mobile phone every 2 weeks. Data from those who changed their normal lifestyles (especially taking up regular PA) will be excluded in the subsequent data analysis.

(Please refer to online supplemental table 1 for the details of the walking programmes).

Patient and public involvement

None.

Outcome assessment

Primary outcomes

Physical health—body composition, resting heart rate and resting blood pressure

The walking effects on participants’ physical health parameters, including body composition, resting heart rate and resting blood pressure, will be assessed. The body composition will be assessed by Tanita MC780U (Tanita Corporation), by which the body mass index, per cent body fat and lean body mass of participants will be recorded. Tanita is considered reliable in body fat measurement, with a significant correlation with traditional Bielectrical Impedence Analysis (BIA) of r=0.90–0.94.⁴⁴ It was also validated with the gold standard measurement, dual-energy X-ray absorptiometry, with a high correlation coefficient (r=0.9 or above) in body fat mass and fat-free mass.⁴⁵

The wrist-worn Fitbit Inspire V.2 (Fitbit) will be used to record the heart rate and exercise intensity of the participants, including resting heart rate, the exercise heart rate changes, as well as the accumulated steps and the duration of the completed steps during each session of the intervention. Systematic review indicated a 0.80 intraclass correlation coefficient of Fitbit in tracking steps and energy expenditure compared with accelerometry-assessed trackers.⁴⁶ The resting blood pressure of the participants will be recorded by Lenus Automatic Blood Pressure Monitor DP65 (MDF instruments).

Walking performance

The time for completing the targeted steps in targeted heart rate zones of each participant in each training session will be recorded for analysis of performance and improvement on walking. All the data will be recorded by the wrist-worn Fitbit Inspire V.2 (Fitbit) and retrieved from the computer after each training session.

Perceived loneliness

The UCLA Loneliness Scale⁴⁷ will be used to measure the perceived loneliness of older adults, by assessing the frequency of experiencing feelings of loneliness. The scale will be rated by a 4-point Likert scale, where 1=‘never’, 2=‘rarely’, 3=‘sometimes’ and 4=‘often’. Positive statements will be reverse coded. Sample items include ‘there are people I can talk to’ (reverse coding) or ‘I feel left out’. The total item score will be summed, with the highest score at 80, while the higher scores indicate a higher level of loneliness. Research indicated a good fit measurement model while applying the Loneliness Scale among older adults above 65 years old.

Perceived social support

Perceived social support will be measured by the Multidimensional Scale of Perceived Social Support,48,50 it is a 12-item scale assessing the level of source of social support, from family, friends and individuals’ significant others. It is rated by a 7-point Likert scale (from 1=‘very stronger disagree’ to 7=‘very strongly agree’). Items included, for example, ‘my family really tries to help me’ or ‘my friends really try to help me’. The Multidimensional Scale of Perceived Social Support was tested reliable and valid among Hong Kong older adults.⁴⁸

PA enjoyment

The 8-item Physical Activity Enjoyment Scale (PACES) ⁵⁰ will be applied to measure the participants’ level of enjoyment after engaging in walking intervention programmes. The 8-item Physical Activity Enjoyment Scale is rated with a seven bipolar rating, with items such as ‘I enjoy it’ (one extreme) to ‘I dislike it’ (the other extreme). In the scale, the negative items (ie, 1, 4, 5 and 7) require reverse coding, and the higher PACES scores indicate a higher level of PA enjoyment.

Secondary outcomes

Health-related quality of life

The Chinese version of the Short Form-36 (SF-36)⁵¹ will be used to measure the HRQoL of older adults. The SF-36 involved two major dimensions—physical health (physical functioning, role limitations due to physical problems, role limitations due to emotional problems and social functioning) and mental health (mental health, vitality, body pain and general health perception). The Chinese version of SF-16 applied among older adults revealed adequate test–retest reliability (r=0.66–0.94). Also, it showed a satisfying Cronbach alpha in both dimensions, at 0.846 and 0.837, respectively, thus showing a high convergent validity in using the Chinese version of SF-36 among older adults.⁵²

Functional fitness—agility and dynamic balance and lower body muscle strength

The agility and dynamic balance, as well as the lower limb muscle strength related to participants’ walking performance, will be measured using the Chair Stand Test, 8-Foot Up and Go Test, respectively, in the Senior Fitness Test (SFT) battery.⁵³ The Chair Stand Test requires participants to rise to a full stand, then return to a fully seated position; and complete as many full stands as possible in the 30 s. The 8-Foot Up and Go Test requires and times the participants to get up from the chair, and walk as quickly as possible around either side of the cone, and sit back down in the chair. The SFT has been widely used in measuring older adults’ functional fitness to assess the effectiveness of PA in the ageing and PA area. The rationales behind the SFT along with the validity and reliability of these testing items have been well described in the Senior Fitness Test Manual.⁵³

Leisure PA participation motivation

Chinese Older Adults Leisure Physical Activity Scale^{54 55} will be used to measure the participant’s level of motivation after engaging in the walking intervention programme. The scale consists of 22 items and is rated by a 5-point Likert scale (from 1=‘stronger disagree’ to 5=‘strongly agree’). The scale was modified from the Physical Activity and Leisure Motivation Scale,^{56 57} yet to be applied among older adults, only three subscales remained in the scale, including social interaction, accomplishment/ego and physical condition and health. Sample items are ‘personally, I exercise (or might exercise) to maintain physical health and function’ or ‘personally, I exercise (or might exercise) to make friends and maintain friendships’.

In-depth interview

The interview guide uses the RE-AIM (Reach, Effectiveness, Adoption, Implementation, Maintenance) framework.⁵⁸ The RE-AIM framework has been mostly applied in public health and health behaviour change programme evaluation. It has covered diverse contents that could be adapted in various settings, including clinical, community and corporate settings.⁵⁷ The RE-AIM framework provides qualitative information that allows investigators/programme developers to improve implementation during the intervention, including the intervention’s maintenance level.⁵⁹ Therefore, the results and findings of the interviews will be used to improve future interventions, as well as references for developing an operation manual for implication and generalisation. Please refer to the online supplemental document 1 for the interview guide.

Data analysis

Descriptive statistics will be used to describe baseline characteristics such as gender, age, living status (alone or with family), body height, body weight, resting heart rate and resting blood pressure of the participants in the study. The primary outcomes will be analysed using an intention-to-treat approach, and missing data will be replaced using the last observation carried forward method. The statistical significance level will be set at p<0.05. All data will be analysed using SPSS V.26.0 (IBM, Armonk, New York, USA). For the within-group and between-group test (time×group) will be tested using the one-way repeated measure analysis of variance will be applied to determine the changes in each outcome parameter among/between the three time points. Post hoc analysis with Bonferroni correction will be conducted to explore the differences between the pretest and post-test, as well as the post-test and follow-up test. The mean differences with 95% CIs will be reported. Furthermore, a one-way analysis of covariance with the baseline value as a covariate will be conducted at the post-test, and a follow-up test will be conducted to determine the group effect on each outcome parameter. Subsequently, the differences between the intervention groups and the CG will be analysed through planned contrasts.

For the in-depth interview, the transcripts collected from the interviews will be qualitatively analysed using thematic content analysis on NVIVO V.12 (QSR International). The study will employ thematic synthesis and analytical induction techniques, such as tag creation, category creation and category analyses, to discern, evaluate and document patterns that characterise the participants’ attitudes and perceptions of the intervention programme.³⁷

Ethical approval and dissemination

The current study involves human participants, and the research protocol has been approved by the research ethics committee at the Hong Kong Baptist University (Ref: R2022-2023-0013). All participants will be provided written informed consent to participate (please refer to online supplemental document 2). All participants will be recruited following the principle of voluntariness, and their data will be kept confidential. Informed consent letters will be signed by the selected participants prior to data collection. The outcomes of the intervention protocol will be disseminated in the form of manuscript publications.

Discussion

The proposed randomised control trial is considered the foremost research study that aims to compare the effects of supervised group-based, unsupervised group-based, and unsupervised individual-based PA in Hong Kong. While walking is one of the most common and easily accessible types of physical activities among Hong Kong, older adults, the intervention programme and outcomes are expected to create a mass community impact on promoting active ageing in Hong Kong. Most importantly, the comparison between supervised, unsupervised group-based and individual-based walking intervention could contribute to the literature gap and identify whether group-based exercise is more beneficial than individual-based exercise programmes. In the long term, a longitudinal study on tracing older adults’ walking behaviour, and physical and psychological status could be further explored. While the proposed RCT aims to provide valuable insights into promoting active ageing among older adults in Hong Kong, there are several limitations to consider regarding a walking-based PA intervention. First, walking may not be as engaging for older adults as other types of more varied exercise programmes. As walking can become repetitive over time, it risks higher attrition rates as motivation and enjoyment may decline compared with activities with more variation. Second, supervised walking sessions require coaches to maintain the line of sight of all participants for safety. Also, individual differences (including gender and age) in physical ability mean that the intended intensity and duration of walking may not be suitable for all age ranges and health statuses within the older adult demographic. Pacing designs may need individualisation to avoid overexertion or understimulation. In particular, the gender ratio in Hong Kong elderly centres, from which we aim to recruit the majority of participants, is disproportionately female dominated, hence might lead to a more female-favourable outcome. These could significantly limit where and how sessions are conducted, reducing the scalability and generalisability of the programme to other settings. Finally, extreme weather could disrupt consistency in undertaking outdoor walking, especially in less temperate climates, reducing intervention adherence and complicating the interpretation of results. Overall, while walking remains an accessible activity for many older adults, these limitations suggest the need for variability in activity types and walking-related theory to maximise older adults’ participation and programme effectiveness.