A harness for enhanced comfort and loading during treadmill exercise in space

Locomotor and some resistance exercises in space require a gravity replacement force in order to allow 1g-like ground reaction forces to be generated. Currently bungee cords, or other loading devices, interface with the crew member through a harness with a waist belt and shoulder straps. Crew members often find the application of the required loads to be uncomfortable, particularly at the hips. An experimental harness was built that differed from previous in-flight designs by having a wider, moldable waist belt and contoured shoulder straps with additional padding. Eight subjects ran at 100% body weight (BW) loading for a total duration of 30min per day on 12 days over a 3-week period in simulated 0-g conditions using horizontal suspension. A 100mm Visual Analog Scale (VAS)11VAS-Visual Analog Scale. was used to assess harness-related and lower extremity discomfort at the end of each run. The overall rating of harness discomfort decreased from 27mm on the 100mm scale on day 1 to 10mm on day 12, with significant decreases recorded for the back and hip regions as well as the overall harness. The experimental harness allows for repeated exposure to 30-minute bouts of 100% BW loaded simulated 0-g running with levels of discomfort less than 30mm on a VAS scale of 0–100mm. We believe that the use of such a harness during on-orbit exercise countermeasures may allow exercise to be performed at levels which are more effective in preventing bone and muscle loss. •Astronauts on the ISS have felt discomfort from the harness during treadmill exercise.•We present a new harness that is rated as comfortable during repeated use at 100% body weight loads.•The increased comfort may encourage adherence to exercise prescription goals.