Table 2.

Qualitative analysis organised using the theoretical framework of acceptability domains, with implications for future implementation

TFA Domain	Theme	Illustrative Quotes	Implications or solutions
Affective Attitude	Enjoyable format of exercise	“Pleased I’ve done it. I quite enjoyed it” (P3473) “I enjoyed doing it. I was very grateful that I had someone to help me remember what to do, but I enjoyed throwing my arms around and everything.” (P5150)	Emphasise enjoyment of exercise via testimonials to help improve buy in and to increase intrinsic motivation
	Surprised by benefit	“I didn’t know if there wouldn’t be any improvement because they seemed to be so innocuous exercises that I didn’t think they would, but I could feel them as I was doing them…It did, definitely exceed it [my expectations], yes.” (P9075)	Expect some participants expectations to be low and provide encouragement when initially engaging
	Tedious if already active, or repetitive	“No. No, I didn’t deliberately stop. But they were tedious and they… and I forgot to do them” (P1667) “Most of it is pretty positive, the only negative for me was that it was a little bit boring, it was repetitive.” (P9879) “No, I didn’t deliberately stop. But they were tedious” (P1677)	Screen participants based on existing activity levels or exercise behaviour. Tailor the programme to include progression to avoid tedium.
Burden	Easy to fit in and flexible	“The fact that you could do it when it fitted in with your lifestyle was a good factor…as long as I fitted in the two in the day, that was a good part” (P3473) “I felt that the fact that it was structured in that I had to do it twice a day, rather than just do it if it was convenient or whatever, meant that I was more likely to do it. So, I did it virtually all the time.” (P9879)	Make sure participants are aware of the flexibility and low time commitment to enhance initial engagement.
	Requires energy and motivation	“If I was tired during the evening as I said, it was difficult to fit in the second one, so perhaps I felt a little bit of negativity then and I think ‘oh twice a day is a bit too much perhaps.” (P3473) “I: Was there anything that made it difficult for you to make time to do the exercises? R: Only if I had not slept well the night before” (P8182)	Suggest that participants find times when they feel most rested or energised to do the snacks Reiterate that they do not need to wait to the evening.
	Memory issues impact compliance	“Sadly and genuinely I forgot to do the exercises” (P1677) “Forgetting, I think I would find it very difficult to do if I didn’t have someone to help me at home, yes. So my memory and my eyesight.” (P5150)	Find ways to prompt exercise snacks such as environmental cues or support from another person (e.g., spouse, carer).
Ethicality	Appropriate for older age	“Yes, yeah. Winter’s coming we won’t be going out probably so much and then circumstances will change as you get older, we will also start to notice more aches and things.” (P3321) “I mean, I’m 74 now. In ten years’ time, probably more need for me to do that type of exercise then ‘cause I’m not gonna find it so easy as I do now.” (P8443)	Reassure participants of the appropriateness of exercise snacking for older adults as an alternative to traditional exercise.
	Great for non-exercisers	“Positive. I thought it was good for me, I am not doing enough exercise, I should be moving more, and I thought this was a very good way…I thought this two lots of 10 minutes, it’s not too much so I was able to do it…it seems more manageable than having to go for an hour’s walk every day or something like that.” (P2112)	Help overcome exercise scepticism by reinforcing the appropriateness of safe and straightforward exercise snacking format
	Physical limitations impact participation	“I can’t get this arm close to my ear, I can touch my ear with my right arm but because of my shoulder I can’t with the left arm” (P2112) “The standing from sitting thing because I’ve got some arthritis in my knees, it made my knees hurt.” (P9879)	Develop adaptive versions of the core exercises to accommodate differences in physical capability, injury, and pain.
Intervention Coherence	Self-monitoring progress is useful	“The exercises, yeah, I found it helpful just to see how many I’d done the previous day.” (P2112) “That was no problem, in fact it was quite an eye-opener to find some days or some parts of the days I was doing less and other days I was doing more of the sitting to standing exercise. But yeah, I had no problem writing it down.” (P3473) “Not really. I kept the sheet of paper near my sofa, so that encouraged me and reminded me that I needed to do it, but apart from that, no.”(P4583)	Emphasise the utility of logging and tracking progress as an intervention function
	Logging sometimes challenging	“Well, I just got out of the habit of writing it down. I think I mentioned earlier on, it’s no great hardship to write it down but I just got out of the habit of it. I’ll do the exercises and then I’ll forget to write them down or fail to write them down…. So it’s no hardship but if I carry on doing it, as I think I will, I wouldn’t carry on logging it.” (P9879)	Consider ways to make logging simpler or more habitual and automatic.
	Need for clear, visual instruction	“Definitely bigger diagrams… these were small, and I couldn’t see them.” (P5150)	Develop large instruction images and videos to accommodate eyesight issues.
Opportunity cost	Sometimes difficult to prioritise	“No, no, actually I’ve got loads of time, it’s just I’ve got other things to do, that’s all.” (P8084) “I had no problem doing the first one. But sometimes it was harder the days, as the day went on and I hadn’t done the second one, it was quite late in the evening and I felt I really had to push myself to do the second one” (P3473)	Reiterate flexibility in when the snacks can be completed
	Scheduling helped adherence	“Not too bad because there wasn’t the commitment that I had to do it at a particular time each day, so it was flexible to fit in with what I was actually doing on any given day.” (P4583) “None at all. I set two periods of time during the day, morning and late afternoon, and that’s what I did.” (P8443)	Propose to people who might struggle to fit the exercise snacks in or remember them that planning when to do them could help adherence
	Rationalise study to improve buy in	“I feel I would like to know what the purpose is, what you were hoping, you medicos, were hoping to glean from the questioning.” (P1677) “No, not, no, not really. I probably didn’t feel pressured enough to make sure I did do it absolutely… it’s different when it’s ‘if you don’t do this, it’ll mess up our study’ and I would’ve made more effort.” (P3321)	Provide a clearer rationale linking exercise and the functional, health and wellbeing benefits.
Perceived effectiveness	Physical function benefits	“Well, I think they’ve made me think more about staying upright, keeping upright and not slumping and stooping, you know.” (P5150) “Yes. Yes, I think in particular the get up, sit down one and the raise your knees to bang your hands ones, I mean they made me, they just made me sort of feel my legs a bit fitter, yeah.” (P7755) “And I know that the exercises in question because I could feel them pulling on muscles, were going to be beneficial to those muscles.” (P9879) “I was aware that my thigh muscles were a bit stronger when sitting and standing.” (P2112) “Without doubt. My knees have got better because of the sitting up, sit up, downs, and I must admit when I first started with the palm exercises my shoulders were stiff as hell and now, they’re far more fluid to say the least, I didn’t realise I never really moved them much before.” (P4583)	Encourage participants to reflect on the physical feeling post snacking to engage with and appreciate the physical benefit of the programme
	Cognitive and wellbeing benefits	“I think they might have helped my wellbeing a bit. And it gave me a little bit of structure by having to do them” (P3473) “I was hoping that it would give me more strength and mobility n the muscles and the joints that I was using. But I know that physical exercise helps with mental alertness and mental wellbeing” (P9879) “R: Yes, they made me think a bit more. I: Okay. What improvement did you expect to see from these exercises? R: A bit more memory, a bit more thinking.” (P2475)	Reinforce to new participants that the benefits may go beyond impact on cognition, which could help entice people attending a memory clinic or worried about cognitive decline and mental health
	Stimulus too light for some	“No, because I suppose just by the very nature of exercise you expect it to be demanding and it wasn’t” (P3321) “Well, if they did have an effect, I haven’t really noticed it, I just believe it’s good for you.” (P8084)	Build in progression levels to make the exercise snacks more challenging for those with higher physical function
Self-efficacy	Overcame initial apprehension	“I was a bit nervous to start with because I didn’t know what it would entail. When I started it was a little bit stressful but then as I got into it and it became a routine, it became easier and easier.” (P4583)	Reassure participants that the programme is likely to become easier with time if difficult initially
	Social support helpful	“Well actually my wife did it, did any recording that actually happened, I didn’t. So I can’t really answer that.”(P8084) “I’ve even got my wife doing them now.” (P4583)	Encourage involving others in the programme where available to help confidence
	Would like to continue doing exercise snacking	“I probably would do once a day but to be honest, I probably wouldn’t do the second one.” (P3473) “Absolutely, yeah, I’m going to keep up with… not necessarily twice a day, every day but at least once a day, every day.” (P4583) “I feel I should, and I think I would enjoy it and it would be good for me” (P5150) “Well it’s introduced me to it, so I probably wouldn’t have started doing it. I mean I’ve threatened to do lots of things, and I did start swimming regularly, but I’m not much of a swimmer, so I tended to let things go. This is relatively easy, and I can do this quickly, so I think I’ll keep it going.” (P9879)	Provide resources and encouragement to support people to continue after the active intervention period

Where noted in quotes, I = Interviewer; R = respondent