COMPENSATORY MUSCLE ACTIVITY IN TRANSTIBIAL SPRINTERS DETERMINING COMPENSATORY MUSCLE ACTIVATIONS IN SPRINTERS WITH LOWER LIMB AMPUTATION B.R. Moen, OPS-III1 Mentors: J. Howell, M.S, CPO2, F. Van Der Watt, CPO, LPO3, C.P. McGowan, Ph.D.4, A.M. Grabowski, Ph.D.5 1MSOP Candidate at Baylor College of Medicine, 2Director of Prosthetics and Orthotics at Baylor College of Medicine, 3Owner of Van Der Watt Prosthetics and Orthotics, 4Assistant Professor at University of Idaho, 5Assistant Professor at Colorado University, Boulder and VA Eastern Colorado Heathcare System COMPENSATORY MUSCLE ACTIVITY IN TRANSTIBIAL SPRINTERS DETERMINING COMPENSATORY MUSCLE ACTIVATIONS IN SPRINTERS WITH LOWER LIMB AMPUTATION B.R. Moen, OPS-III, J. Howell, M.S, CPO, F. Van Der Watt, CPO, C.P. McGowan, Ph.D., A.M. Grabowski, Ph.D. INTRODUCTION: The aim of this study was to make descriptive analyses of the muscles in the lower extremity of subjects with lower limb amputation during a maximum velocity sprint. Through the use of kinematic measures and electromyography (EMG), the researchers were able obtain a comprehensive picture of the sprinters with amputation. Research was designed to examine the use of compensatory muscle contractures and kinematic differences between comparable able-bodied sprinters and those with amputation performing at the highest levels. The principle aim of the research study was to examine compensatory muscle function in sprinters with transtibial amputation to determine which muscle groups are targeted most to replace speed and power lost by transected plantar and dorsi-flexors. OBJECTIVE: The primary objective was to quantify muscle activation patterns from the unaffected limb and the affected limb of transtibial amputee sprinters in order to identify potential differences between legs. The secondary objective was to quantify muscle activation patterns from sprinters with and without amputation in order to identify potential compensatory control strategies used by athletes with amputations. The tertiary objective was to correlate compensatory muscle patterns to training and strengthening protocols as a means of improving athletic performance and reducing secondary injury in a specified activity. METHODS: The study design utilized repeatable measures in an observational descriptive comparative analysis. Data was collected on five active US Paralympic track and field athletes (AMP), which were paralleled to five able-bodied athletes (NA) of similar caliber, all of which were at or near Olympic performance. Data for the study was collected using a wireless Noraxon Telemyo EMG system, the APDM human movement sensors, video gait analysis, and the Optojump. The researchers designated eight muscles in the lower limb of which the most muscle activation and compensatory patterns during the sprint was anticipated. These muscles were the tibialis anterior (TA), soleus (SOL), lateral gastrocnemius (LG), rectus femoris (RF), vastus lateralis (VL), biceps femoris (BF), semitendinosus (ST), and gluteus maximus (GM). Each athlete was suited with EMG electrodes over the designated muscle bellies and tested for their maximum voluntary contraction (MVC). Once the preliminary testing was complete the athletes were asked to execute 4-30m fly-in sprints at maximum velocity. The testing took place on an outdoor track located at the Olympic Training Center in Chula Vista, California. RESULTS: The researchers have analyzed five steps from the four trials of seven subjects (4 amputees/ 3 non-amputees) running at 8.89 ± 0.29 m/s AMP and 9.74 ± 0.31 m/s NA respectively. Burst duration, mean spike amplitude and integrated area of collected EMG data were analyzed. While some differences and trends are visible in the data, the portions of the data that have been analyzed do not show statistically significant differences between legs. Further analysis of the results is needed to examine all factors and variables. CONCLUSION: While the preliminary results are inconclusive, the researchers expect that a more complete analysis of our data set will enable us to further understand the biomechanics and compensatory mechanisms of sprinters with amputation. 2 COMPENSATORY MUSCLE ACTIVITY IN TRANSTIBIAL SPRINTERS 1. ABSTRACT The goal of this study was to make descriptive analyses of the muscles in the lower extremity of subjects with lower limb amputation during a maximum velocity sprint. Through the use of kinematic measures and electromyography (EMG), researchers were able obtain a comprehensive picture of the sprinters with amputation. The research was designed to examine the use of compensatory muscle contractures and kinematic differences between comparable able-bodied sprinters and those with amputation performing at the highest levels. The principle aim of the research study was to examine compensatory muscle function in sprinters with transtibial amputation to determine which muscle groups are targeted most to replace speed and power lost by transected plantar and dorsi-flexors. 2. INTRODUCTION In the world of Paralympic sport, transtibial sprinters have entered into the 10-second range for the 100m sprint. These athletes are reaching extraordinary speeds despite not having the knowledge to fit them properly or a true understanding of their full body mechanics. Athletes performing at the elite level are pushing their bodies, talents and prosthetic limbs to great lengths with limited understanding of compensatory muscle function and joint biomechanics. As the fitting of running-specific prostheses (RSP) becomes more of a common occurrence, prosthetists, coaches and researchers, realize that the lack of knowledge about amputee sprinters is only preventing athletes from reaching their full potential. Prosthetists are fitting these amputee sprinters using able-bodied mechanics as the gold standard while knowing that amputee mechanics operate differently due to the lack of body mass, major articulating joints and bi- COMPENSATORY MUSCLE ACTIVITY IN TRANSTIBIAL SPRINTERS articulating muscles. Therefore, a better understanding of the amputee mechanics is necessary to fully comprehend the training, coaching and fitting necessary for amputee sprinters. There are very few studies analyzing the patterns of transtibial compensation with the use of RSPs. Findings suggest that lower limb amputee sprinters use a multitude of compensatory patterns on the unaffected and affected limb, especially when moving at such high velocities.2,6 Compensatory patterns such as increased hip and knee extension moments on the affected limb as well as an increased amount of work at each of these joints respectively.3 The affected limb (AL) is limited by the amount of vertical ground reaction force (GRF) it is able to produce due to the RSP and muscle weakness. The unaffected limb (UL) compensates for this lack of generated vertical force by producing on average nine percent more. The limit in vertical force generation on the AL is said to be the major limiting factor when it trying to compete at maximum velocities5. Studies done analyzing amputees running at various velocities on SACH feet have shown that there is an increased level of total work done on the sound limb but that the kinematics are comparable to able-bodied athletes. There is about a 70% increase in total work done on the unaffected limb as a whole when compared to able bodied athletes.4 Due to the developments in RSPs, amputees are now able to achieve the same up-on-the-toes gait patterns as able-bodied sprinters. This similar gait pattern creates overall similar kinematics to able- bodied sprinters.2 It has yet to be investigated how exactly the RSP impacts compensatory muscular activity on the sound limb. Whether and how unilateral transtibial sprinters use muscles in the unaffected limb to compensate for the lack of foot and ankle on the affected limb is the focus of this paper. Five elite unilateral transtibial sprinters operating at maximum velocity, wireless EMG and high- speed cameras were used to study these compensatory patterns. The patterns demonstrated on the 4 COMPENSATORY MUSCLE ACTIVITY IN TRANSTIBIAL SPRINTERS AL were compared to the muscular patterns and kinematics on the UL, as well as to the limb of an able-bodied athlete of comparable athletic level. The muscles chosen to explore during this study, have been selected based on prior investigations of able-bodied sprinters. The quadriceps are expected to fire from late swing to mid-stance, the hamstrings and gluteus maximus were activated the most during mid-swing to mid-stance. While the contrast of able-bodied to corresponding UL joint angles have in past studies been compar4able and increasingly similar as you reach the hip,2 these muscles work the hardest to propel the limb forward and transfer energy to the opposing, AL during the sprint cycle.4 Due to this activity in able-bodied sprinters, the research team hypothesized that the activity in the proximal thigh musculature, specifically the hip extensors, would be greater in the UL compared to the AL during a maximal velocity sprint in elite transtibial sprinters. 3. OBJECTIVES The primary objective was to quantify muscle activation patterns from the unaffected limb and the affected limb of transtibial amputee sprinters in order to identify potential differences between legs. Differences will be determined through a comparison of surface EMG data and gait patterns between the unaffected and affected limbs. The secondary objective of this study was to quantify muscle activation patterns from sprinters