Increasing leg strength, leg power and overall balance can improve mobility and reduce fall risk. Sensor-based assessment of peak power during the sit-to-stand (STS) transfer may be useful for detecting changes in mobility and fall risk. Therefore, this study investigated whether sensor-based STS peak power and related measures are sensitive to the effects of increasing leg strength, leg power and overall balance in older adults. A further aim was to compare sensitivity between sensor-based STS measures and standard clinical measures of leg strength, leg power, balance, mobility and fall risk, following an exercise-based intervention. To achieve these aims, 26 older adults (age: 70-84 years) participated in an eight-week exercise program aimed at improving leg strength, leg power and balance. Before and after the intervention, performance on normal and fast STS transfers was evaluated with a hybrid motion sensor worn on the hip. In addition, standard clinical tests (isometric quadriceps strength, Timed Up and Go test, Berg Balance Scale) were performed. Standard clinical tests as well as sensor-based measures of peak power, maximal velocity and duration of normal and fast STS showed significant improvements. Sensor-based measurement of peak power, maximal velocity and duration of normal STS demonstrated a higher sensitivity (absolute standardized response mean (SRM): ≥ 0.69) to the effects of training leg strength, leg power and balance than standard clinical measures (absolute SRM: ≤ 0.61). Therefore, the presented sensor-based method appears to be useful for detecting changes in mobility and fall risk.

Leg muscle strength (LMS) and leg muscle power (LMP) are determinants of aspects of functional status and important parameters for measuring intervention effects in older adults. Field tests are often used for the evaluation of LMS and LMP in older persons. However, criteria important for the application of strength and power related field tests in older adults have not been systematically taken into account and are not yet fully listed and described in a single publication. Therefore, this paper describes criteria important for the application of strength and power related field tests in older adults. In addition, strength and power related field tests commonly used in older adults are evaluated by using the described criteria. Based on this evaluation, this paper provides a perspective on the further development of field tests. Criteria important for strength and power related field tests are: adequate accuracy, precision, concurrent validity, clinical validity, practical feasibility and pure strength or power outcomes. Commonly used strength and power related field tests do not meet all the aforementioned criteria. Therefore, further development of field tests is necessary. Mobile sensing systems are potentially useful for the evaluation of LMS and LMP in older adults. Mobile sensing systems do not have the limitations of commonly used field tests and provide important additional advantages. In particular, mobile sensing systems offer the opportunity of continuous monitoring during free-movement in the home-environment, thereby reducing the need of standardized assessments by health-care professionals. Future studies should examine the clinical validity of mobile sensing systems and evaluate the application of sensor technology in exercise-based interventions.

No abstract