Table 1.

Intervention components mapped onto items 1 to 9 of the TIDieR Checklist [31]

Item Number	Item
Brief Name
1.	Peer-support PA intervention for older adults
Why?
2.	Peer-support intervention that aimed to increase older adults` PA levels. Peer support was provided during the sessions in the form of motivation and assistance with activities when required. This form of intervention has previously been recognised to increase adherence to PA [15–17]. Attendance data showed that 93% of attendees were retired, 76% were female from a white ethnic background and 26% lived > 3.6 miles from the venue.
What?
3.	Intervention resources
	Consultation paperwork – A physical activity readiness questionnaire (PARQ) was completed to ascertain if the service user had any medical conditions or medications that the instructor should be aware of. Once completed, a brief conversation about service user goals and service provision was undertaken where possible with the exercise referral instructor.
	Specialised, adapted gym equipment (hydraulic / air resistance controlled) was available for gym-based sessions in a specific lower-gym room that was only accessible to intervention users. All users also had access to a main sports hall where equipment was available for activities such as netball, football, or bowls. The swimming pool was also available for swimming or aqua sessions.
4.	Procedures and key components
	The intervention adhered to the National Institute for Health and Care Excellence (NICE) guidance for exercise referral [32] which advocates a focus on inactive individuals and ongoing support, with self-referral and health care professional (HCP) referrals accepted.
	Eligibility: Open access to all ages, but targeted individuals aged over 50 years. Medical conditions were allowed, but not essential for access.
	Week 1 Consultation (induction): Introduction to the fitness centre, health screening and peer-support sessions available conducted by the exercise referral instructor. Mainstream gym induction (where possible) also completed by the exercise referral instructor so that service users could attend the main gym in addition to the intervention sessions in the lower gym. 12-week subsided access to peer-support classes, swimming and main-gym commenced after the induction.
	Week 12: At the end of the subsidised period, service users were able to continue attending the sessions (gym-based classes, walking football, walking netball, bowls, swimming and aqua fit) at the centre, but were now required to either pay a non-subsidised entry fee per session or join on the off-peak membership offered by the fitness centre.
Who will provide?
5.	Referring health professionals: Referrals were accepted from all health professionals (GP’s, physiotherapists, nurses, etc.) but data showed that GPs were the chief source of referrals (31%), followed by health trainers (17%).
	Exercise referral practitioners: Based at local authority fitness centres they were qualified to lead the sessions with support of the peer volunteers.
	Health trainers: Local authority staff who worked in the community and signposted the general public to health-related services. Health Trainers were already trained to provide lifestyle advice for numerous health-related behaviours (physical activity, weight loss, smoking cessation, nutrition etc.) and could signpost service users to the peer-support intervention.
	Peer volunteers: People who had (usually) attended the peer-support intervention themselves (some remained service users) and had given up their time to assist in the running of the sessions. They set up sessions by moving equipment, monitored the timings throughout sessions, motivated service users, increased interaction levels with service users and hosted external events such as raffles, Christmas parties, etc. Peer volunteers had no formal qualifications and could not lead sessions independently, therefore a staff member was always present due to insurance guidelines.
	Centre manager: Oversaw session provision by ensuring staff were present. Ensured all peer volunteers were registered with the local authority and provided a suitable venue space and equipment for sessions to take place.
How?
6.	Peer-support sessions: Provided in face-to-face format to small groups of service users (8–15 participants) by the exercise referral instructor.
Where?
7.	All service user consultations and activities took place at the local leisure centre.
When and how much?
8.	The peer-support intervention had an initial 12-week subsidised period and supported older adults to increase their PA levels. The programme consisted of daytime (9 am – 3 pm) group-based sessions such as circuits, walking football, walking netball, indoor bowls, aqua and chair-based exercise which were primarily led by a qualified exercise referral instructor and supported by peer volunteers. Swimming could also be completed in designated sessions without specialist supervision. Each session lasted approximately 45 min to 1 h.
Tailoring
9.	The peer-support sessions were group-based but recommended to service users based on individualised needs alongside their PA preferences. All sessions were aimed at service users aged 50 or over.