Kyle Leister

Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)


Exercise Science


Tiago Barreira


Amputation;LASSO;Mobility;Physical Activity;Prosthesis;Validity

Subject Categories

Kinesiology | Life Sciences


Outcome measures can be utilized to assess physical function in controlled settings, but do not provide a comprehensive view of free-living mobility for individuals with transtibial amputation (TTA). We sought to expand upon established clinical-based outcome measures by developing and cross validating two equations for predicting daily steps. The relationship between health state predictors and performance on 1) the Timed Up and Go (TUG) Test, and 2) the Prosthetic Limb User’s Survey of Mobility (PLUS-M) was also assessed via the model predictions. Adults with TTA were assigned activPAL and Fitbit accelerometers to wear for seven days. Participant data were randomly separated into training (n = 80) and testing (n = 26) groups. LASSO regression with 3-fold cross validation was implemented to construct each equation according to a participant’s health state, TUG Test, L Test of Functional Mobility, and PLUS-M data. Each equation’s validity was assessed in the testing group. An inverse relationship was noted between daily steps and TUG Test performance and higher PLUS-M T-scores were associated with greater daily steps. The equation overestimated steps for those with significantly low daily steps and underestimated steps for those with significantly high daily steps, which is to be expected given the nature of linear regression. We also assessed the validity of the Fitbit Inspire 3 for assessing steps among individuals with TTA. Daily step data were compared between the Fitbit Inspire 3 and the activPAL 3. The Fitbit overestimated physical activity by estimating higher daily steps compared to the activPAL. Because of the significant mean differences between the devices, the activPAL and Fitbit are not interchangeable for estimating steps in this group. The results will be interpreted and explored in the context of prosthetic rehabilitation and underscore the importance of personalized mobility assessments and interventions aimed at improving the free-living mobility of individuals with TTA.


Open Access