The configuration of devices, which people with lower limb disability interact with during walking and sport, may influence muscle activity, reduce metabolic effort, and improve performance. Typical passive-elastic walking prostheses cannot fully replicate the function of the biological ankle and foot, which may result in altered muscle activity and greater metabolic effort while walking. A stancephase powered prosthesis that works in series with a passive-elastic prosthetic foot has been developed to provide people with transtibial amputation powered plantarflexion while walking. In chapter 1, I determined how use of a powered prosthesis during walking on level and sloped ground affects a user’s leg muscle activity. In chapters 2 & 3, I examined how the stiffness of a passive-elastic prosthetic foot and the power setting of the powered prosthesis affects the user’s leg muscle activity and metabolic effort while walking on level ground. In chapter 4, I explored how performance of sled hockey athletes with lower limb disability is influenced by different lengths of hockey sticks.

In chapter 1, my co-authors and I present a manuscript published in Royal Society Open Science where we measured leg muscle activity when people with transtibial amputation used passive-elastic and powered prostheses to walk at 1.25 m/s on level ground and 3°, 6° and 9° uphill and downhill slopes. Muscle activity is associated with metabolic effort, and therefore may help to explain metabolic effort differences between use of passive-elastic and powered prostheses. We found that use of the BiOM prosthesis increased unaffected leg lateral gastrocnemius integrated electromyography (EMG) on downhill slopes and affected leg biceps femoris on +6° and +9° slopes, and decreased unaffected leg rectus femoris on uphill slopes, unaffected leg vastus lateralis on +6° and +9°, and soleus and tibialis anterior on a +9° slope compared to a passive-elastic prosthesis.

In chapters 2 & 3, my co-authors and I present work from two manuscripts where we examined the effects of passive-elastic prosthetic foot stiffness category and power setting of a stance-phase powered prosthesis on leg muscle activity and metabolic cost of people with transtibial amputation during walking. We found that when people with TTA used different stiffness categories of a passiveelastic prosthetic foot alone and in series with the BIOM powered prosthesis at different power settings, unaffected leg vastus lateralis and affected leg rectus femoris activity decreased when using stiffer compared to less stiff passive-elastic feet, regardless of whether or not they were used in series with the BiOM prosthesis. Additionally, unaffected leg biceps femoris and lateral gastrocnemius activity decreased and affected leg rectus femoris activity increased when people with TTA used the BiOM prosthesis at recommended and greater than recommended power settings compared to use of a passive-elastic prosthesis alone. Furthermore, we found that people with TTA using the BiOM powered prosthesis at 10 and 20% greater than recommended power settings to walk on level ground at 1.25 m/s reduced their net normalized metabolic power by 5.2 & 6.7%, respectively, compared to use of an ESAR prosthesis. Regardless of prosthetic power, we found no effect of prosthetic foot stiffness category on net metabolic power. Our findings indicate that people with transtibial amputation and prosthetists prescribing powered prostheses should target greater than recommended power settings in series with a passive-elastic prosthesis with greater than recommended stiffness.

In chapter 4, my co-authors and I explored how stick length affects the performance of elite sled hockey players. There are currently no evidence-based guidelines for stick length in the sport of sled hockey. We found that stick length changes within four inches do not significantly change the metabolic effort, maximum speed and acceleration, and agility of sled hockey athletes.