Application of Exercise Snacks across Youth, Adult and Clinical Populations: A Scoping Review

Abstract

Background: Interest in 'exercise snacks' has increased, yet a comprehensive and holistic review of this novel concept is lacking. We aimed to map global research on 'exercise snacks', across youth, adult and clinical populations through a scoping review.

Methods: A systematic search was conducted in six databases. Grey literature searches were also conducted. Studies whereby participants were prescribed a structured bout of intense exercise dispersed across the day, or the exercise was explicitly defined as a form of 'snacks', in any setting were included. We used the Consensus on Exercise Reporting Template (CERT) to assess the completeness of exercise descriptions. Data were recorded into spreadsheets, then descriptively analyzed and summarized in graphic form.

Results: The 45 publications meeting our inclusion criteria represented 33 original studies. These 33 studies enrolled a total of 1118 participants, with a median sample size of 24. Studies were categorized as either acute (n = 12) or chronic (n = 21) trials with both trial types performed across a wide range of participant ages (range 8.7 to 78 years) but mostly conducted on healthy adults and older adults. The majority of studies (20/33) defined the concept as 'exercise snacks', with study context being predominantly the laboratory or home. A wide variety of exercise modes (e.g., cycling, stair climbing, body weight exercises) and comparator conditions (e.g., moderate intensity continuous exercise, prolonged sitting, non-exercise controls) were used. 'Exercise snack' intensity was prescribed more frequently than it was reported, and, of the available data, mean intensity was estimated at 76.9% of maximal heart rate and 5.2 Arbitrary Units (AU) on the Ratings of Perceived Exertion (RPE) CR10 scale. Study outcome measures were predominantly cardiovascular, metabolic, muscular, and psychological, with studies mostly adhering to the CERT, though there was underreporting of detail for the exercise provider, motivation strategies, adverse events and intervention fidelity.

Conclusion: The 'exercise snack' concept is being increasingly used to cover an array of exercise models. The most common protocols to date utilize body weight exercises or stair climbing. We recommend 'exercise snacks' terminology is consistently used to describe protocols whereby short, purposeful structured exercise is dispersed throughout the day. Future studies should provide detailed descriptions of their 'exercise snacks' model, through exercise and adverse event reporting checklists.

Fig. 1

PRISMA flow chart outlining study inclusion process

Fig. 2

Publication year and participant mean age for the 33 original studies in our scoping review

Fig. 3

Upset plot showing the frequency and different combinations of populations and population descriptors across the 33 exercise snacks studies

Fig. 4

Frequency of study concept (i.e., exercise definition) by context (i.e., location) grouped by exercise mode

Fig. 5

Bar chart of study comparators colored by study design

Fig. 6

Bar chart showing the different ways of exercise prescription, grouped by exercise mode, along with the proportion of studies reporting a prescribed exercise intensity and reported exercise intensity (inset)

Fig. 7

Mean study exercise snack heart rate (n = 10) and RPE (n = 9*) colored by exercise mode and plotted against exercise snack duration.* Reference [96] reported exercise intensity via RPE (~ 6.0 AU) but provided no precise exercise snack duration

Fig. 8

Proportion of reported, not reported and not applicable items for each study when evaluated against the 16 CERT items

Fig. 9

Upset plot showing the frequency and combination study outcomes