Table 1.

Initial program theories about how SAGE works for most participants

Initial program theory		Supporting theories from the literature
1.	People persevere with the program because they feel health benefits (e.g. improved balance and mobility) which boost feelings of strength and independence	PA generates feelings of physical and psychological wellness [58], and yoga does this particularly effectively, including for older people [33, 59, 60]
2.	The perceived quality of yoga instructors is important for making people feel safe and confident. This includes instructors who understand the needs of older people	The quality of instructors affects older people’s feelings of safety and confidence in PA [5]. The concept of therapeutic alliance is key to understanding instructor/participant relationship quality [61]
3.	Tailoring of the classes is crucial. People must feel they can participate according to their abilities and health needs	Tailoring of PA programs is a key motivator in adherence for older people [5, 62, 63]. Fall prevention interventions should be tailored for targeted recipients to maximise safety and effects [64]
4.	Group classes facilitate social connections which may add to the enjoyment of classes	Many empirical studies [62, 65–68] and theories back this concept including self-determination theory [69] and the upward spiral theory of lifestyle change [70]
5.	Free classes are an incentive to give yoga a go and stick with it long-term	Subsidised costs increase participation in PA [71, 72]. The ‘zero price effect’ [73] increases perceptions of value