Over the last two decades, technological advances have increased our ability to measure human movement in real-world environments (Adams et al., 2021, Dobkin and Martinez, 2018, Wang and Adamczyk, 2019). For instance, with the development of inertial measurement units, we can measure an individual’s physical activity (Bammann et al., 2021), postural control (Patel,Pavic,and Goodwin, 2020), gait (Washabaugh et al., 2017), and sedentary behavior (F et al., 2019). Rather than having only a snapshot of a person’s movement at one point in time, technology can assess movement over multiple hours and days. Most sensors, however, measure kinematics such as acceleration (Chow et al., 2021, Patel et al., 2022). While understanding body position and acceleration can provide important health metrics, measuring force is also needed to understand limb and joint loading during various activities.

Force-sensing insoles provide a novel way to measure in-shoe forces outside of a laboratory setting (Cudejko,Button,and Al-Amri, 2023). Unlike force plates or instrumented walkways, insoles are fitted into a person’s shoes and can be worn during everyday activities in various settings (Renner et al. (2019)). Insoles can measure forces acting on the plantar surface of the foot during movement activities. While insoles are valid and reliable during gait and balance activities compared to force plates, previous studies largely utilized insoles in research settings (Peebles et al., 2018, Renner et al., 2019). Few studies have utilized the portability of insoles to measure loading in the real-world over multiple days.

The Incorporating Nutrition, Vests, Education and Strength Training (INVEST; NCT04076618) study is a randomized controlled trial that compares the effects of weight loss alone, weight loss plus weighted vest use, or weight loss plus resistance training (RT) on bone mineral density and fracture risk indicators (Miller et al., 2021). In older adults living with obesity, intentional weight loss through diet and exercise can improve overall health (Villareal et al., 2006a, Villareal et al., 2006b, Villareal et al., 2011), but weight loss is also associated with bone mineral density loss (Ensrud et al., 2003). Both RT and weighted vests aim to increase mechanical stress through musculoskeletal loading while losing weight to maintain bone health (Daly et al., 2005, Shah et al., 2011, Villareal et al., 2006a, Villareal et al., 2006b). However, the overall amount of loading that each activity creates and thresholds needed to minimize bone mineral density loss is unclear.

The INVEST trial offers a unique opportunity to use insoles to continuously monitor lower limb loading during intentional weight loss. As an ancillary pilot study to the INVEST trial, we implemented force-sensing insoles to generate daily limb loading metrics through continuous, real-world monitoring. As such, the purpose of this study was to determine the feasibility of using insoles in older adults across the three treatment arms of the INVEST trial. We hypothesized that we would demonstrate successful feasibility, defined as: 1) at least 60 % recruitment rate of participants enrolled in INVEST, 2) at least 80 % adherence rate of older adults wearing insoles, 3) at least 75 % usable data of real-world capture, and 4) at least 75 % participation satisfaction with using the insoles.