An investigation into participant adherence within high intensity interval training

High Intensity Interval Training (HIIT) has been shown to be a time efficient and adherable method of exercise when performed under laboratory, supervised conditions. Whilst this is beneficial as HIIT has the ability to promote health improvements, there is limited research which investigates the adherence of HIIT out with a laboratory, in an unsupervised environment. Furthermore, there is only a finite amount of literature which specifically investigates HIIT adherence and enjoyment over a timeline greater than 12 weeks, in an unsupervised capacity. The overall aim of this thesis is to investigate adherence to HIIT. This will be achieved through a scoping review to map the current literature base on HIIT and adherence, and a remotely monitored feasibility randomised controlled trial where adherence, compliance and enjoyment to a Sprint Interval Training (SIT) intervention will be measured. Collectively, this research will aim to guide future research into the topic area in order to improve engagement with HIIT and reduce the negative health related effects of lack of exercise. The objectives of this thesis are: 1) To provide a comprehensive overview of the current literature on adherence to HIIT, identifying key patterns influencing participation. 2) To investigate adherence, compliance and enjoyment to SIT in a novel feasibility randomised controlled trial. 3) To generate evidence-based recommendations for future research, with a focus on improving adherence to HIIT protocols and addressing gaps in the literature. The scoping review was conducted in alignment with the Joanna Briggs Institute (JBI) methodology for scoping reviews. The following databases were searched: PubMed, Scopus, AMED, CAB Abstracts, Library Literature & Information Science Full text, Medline, SPORTDiscuss, CINAHL, Library Information Science & Technology Abstracts Medline, Web of Science and Google Scholar. Grey literature was also identified in this manner through databases including, OpenDOAR, OpenAIRE, Open Air @ RGU, EThOS, OATD, TRIP, MEDNAR, National Institute for Health and Care Excellence (NICE), ICTRP Search Portal, Open Trials, Clinical Trials.Gov, ISRCTN registry, EU Clinical Trials Register and Centre Watch. Titles and abstracts were independently screened by two reviewers to determine inclusion or exclusion. Full text screening was independently completed by two reviewers. At each stage of screening, discrepancies were resolved via discussion, and disagreements resolved by a third reviewer. Studies gained from searching study reference lists were assessed for relevance based on titles and abstracts, with those meeting the required inclusion criteria incorporated within the full text screening stage. A remotely monitored feasibility randomised controlled trial was then undertaken, Participants (n=24,18-65 years; 15 male) were randomly assigned to one of 3 groups: HIIT-1, HIIT-2 or HIIT-3. Following assignment, participants undertook a familiarity session. All HIIT groups undertook 20 weeks of HIIT on a Wattbike within their local gymnasium unsupervised. Each session consisted of 8 or 12 'maximal effort' 10 second sprints, interspersed with 30 seconds of active recovery at or above 50W, 2 or 3 times per week. Upon completion of the 20 week intervention, participants completed a Physical Activity Enjoyment Scale (PAES). Two hundred and seventy two studies were included, reporting high levels of adherence within the literature base, as 60 studies reported 100% adherence, with a total of 237 studies reporting adherence >80%. Randomised controlled trails were most common (n=209), while interventions delivered in clinical settings (n=172). Populations were mixed, as 134 studies reported sedentary populations, while a large number of studies included a supervised protocol (n=255). Although likely impacting adherence numbers, a total of 55 studies required participants to achieve a specific number of sessions attendance prior to being included for analysis, while 205 studies utilised heart rate monitors for participants. Although adherence to HIIT protocols remains high, the predominance of clinical based, supervised interventions limits the effectiveness of the findings. Further research in an unsupervised, real life setting is required to further understand adherence to HIIT. Adherence remained low across each group, with HIIT-1 exhibiting the highest average adherence and enjoyment (Adherence=30.31%, Enjoyment=76.59%). HIIT-2 demonstrated the lowest adherence (Adherence=8.71%, Enjoyment=60.43%). With HIIT-3 remaining between the two groups (Adherence=22.81%, Enjoyment=72.49%). Compliance to the prescribed protocol intensity remained high with a compliance rate of 97.7%, as only 4 sessions out of 179 sessions completed by all participants were deemed to be non-compliant compared to the criterion session of each participant. Three participants completed >97% of sessions whilst also scoring >80% on the PAES suggesting higher enjoyment levels are associated with better adherence. The aim of this thesis was to investigate adherence to HIIT, and was achieved by undertaking a scoping review to map the current literature base on HIIT and adherence, but also to conduct a remotely monitored feasibility randomised controlled trial investigating adherence to SIT over a 20 week period in an unsupervised, real life setting.