Long-lasting sitting and standing is related to several health risks and alternatives to these positions are needed. This study compared muscle activity, heart rate, performance, and comfort between sitting, standing, and using a stable sit-stand-support with four different seat angles. Twenty-one subjects fulfilled three tasks (typing, a tweezing task and a task simulating ironing) in every position for five minutes. The heart rate was higher using a sit-stand-support and standing compared to sitting. The activity of the m. erector spinae was similar or lower using a sit-stand-support compared to sitting or standing. The activity of the m. gastrocnemius was in between the levels of sitting or standing. No significant differences were observed for the performance. The sit-stand-support most often was preferred to sitting. A stable sit-stand-support may be a solution for short interruptions of sitting or standing. Relevance to industry: A stable sit-stand-support may be an option for short interruptions of sitting and standing and may reduce the consequences of these static positions. Keywords muscle activity, sit-stand-support, sitting Katzmarzyk et al., 2009; Matthews et al., 2012). On the other side, prolonged standing is associated with health risks, too. Reported health risks of prolonged standing are low back pain (Andersen et al., 2007), pain in the lower limbs (Graf et al., 2015), chronic venous disorders (Sudol-Szopinska et al., 2011) and plantar fasciitis (Werner et al., 2010). These results show that prolonged sitting as well as prolonged standing should be reduced. Different options are discussed to reduce sitting time. An often discussed possibility to reduce sitting time is a sit-stand table (Chau et al., 2014; Gao et al., 2016). Studies showed that sit-stand-tables were well accepted but the reduction of sitting time was only moderate. Further options are active breaks (Bailey and Locke, 2014), treadmill desks (Koepp et al., 2013), or cycling workstations (Elmer and Martin, 2014). Finally, a sit-stand-support could be a possibility to reduce sitting time as well as standing time. A big variety of sit-stand-supports are on the market, but only little research analyzing their effect on the working subject exist. Furthermore, all studies analyzed the effect of one sit