Galinsky 2007.

Methods	Cross‐over RCT. Approximately half (23) of the volunteers in each exercise condition were assigned at random to work for 4 weeks under conventional schedule and then switch to the supplementary schedule for the second 4‐week phase. The remaining 22 volunteers in each exercise condition were assigned at random to experience the opposite sequence of rest break conditions.
Participants	Data‐entry operators (seasonal employees) working at an Internal Revenue Service centre, Cincinnati, OH, US. The study sample was recruited from 1 area of the centre containing workstations for 101 individuals, 90 of whom volunteered to follow the study protocol.
Interventions	The study compared supplementary breaks with conventional breaks. Half of the 90 volunteers were assigned at random to the stretching exercise condition and half were assigned to the no‐stretching exercise condition. The 8‐week study period was divided into two 4‐week phases in which all participants alternated between the conventional and supplementary rest break schedules The conventional break schedule included one 15‐minute break in the middle of the first half of the work shift and one 15‐minute break in the middle of the second half of the work shift. The supplementary break schedule included those same 15‐minute breaks, and also included a 5‐minute break during each hour of the work shift that otherwise did not contain a break. For each 8‐hour shift, the supplementary schedule provided 4 extra 5‐minute breaks for a total of 20 extra minutes of break time. All participants were encouraged to get up and walk away from their workstations during each break, regardless of their assigned break schedule or exercise condition. Under each schedule, a 30‐minute lunch period, additional to the 8 hours of work and break time, occurred in the middle of the shift. Participants in the exercise condition viewed a demonstration of the stretching exercises performed by the principal investigator with opportunities for questions and answers. They also kept a paper copy of exercise instructions at their workstations. They were instructed to do the stretches at the beginning of each break in the order specified in the instructions. The first 6 stretches were performed while seated and the last 3 stretches could be done while standing or walking. The 9 stretches required no more than 2 minutes to complete.
Outcomes	Primary outcome Musculoskeletal discomfort ratings (feeling state) for several parts of the body, including the neck, shoulders, upper arms, elbows, forearms, wrists, hands, back, buttocks, and legs. The musculoskeletal discomfort was made using a 5‐point category rating scale in which the whole numbers 1 to 5 indicated ratings of 'none at all', 'a little', 'moderate', 'quite a bit', and 'extreme', respectively.
Notes	The data for the conventional and supplementary break cycle consists of the combination of participants in both exercise and no exercise groups. The effect of breaks alone cannot be isolated. The author provided additional data on mean and standard deviation.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	There was no information on sequence generation. The only information available is that "… the exercise group and the non‐exercise group… were assigned at random to work for 4 weeks under the Conventional schedule and then switched to the Supplementary schedule for the second 4‐week phase" and "approximately half (23) of the volunteers in each exercise condition were assigned at random to work for 4 weeks under the Conventional schedule and then switched to the Supplementary schedule for the second 4‐week phase".
Allocation concealment (selection bias)	Unclear risk	There was no information on allocation concealment
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Blinding was not possible but the risk of performance bias was deemed low for a rest‐break cycle as the implementation consisted of a strict protocol. The participants "use custom‐made electrical timers, attached to the top of each video display terminal, to automatically signal their scheduled breaks". However, as this study compared 2 exercise regimens that were not blinded, the risk of bias was deemed high for the combination of the 2 interventions.
Blinding of outcome assessment (detection bias) Musculoskeletal disorders	High risk	The outcome had only subjective symptoms, i.e. musculoskeletal discomfort ratings (feeling state).
Incomplete outcome data (attrition bias) All outcomes	High risk	Out of the 90 who volunteered to follow the study protocol only 51 were deemed to have complete data for analysis. According to the text "An individual's data set was deemed incomplete if more than 4 consecutive days of questionnaires were missing, or if more than a total of 8 days of questionnaires were missing from either the first or second 4‐week period of the study".
Selective reporting (reporting bias)	Low risk	The risk of selective reporting (reporting bias) was deemed low as all outcomes were reported, the author reported on non‐significant outcome: "In the stretch group, workers reported stretching during only 25% of conventional breaks and 39% of supplementary breaks, and no significant effects of stretching on discomfort or performance were observed".
Other bias	High risk	There was no comparison of the 2 intervention groups. Potential of carry‐over effect, as the authors did not state having used a wash‐out period.