THE INFLUENCE OF GROUND REACTION FORCES AND KNEE KINEMATICS IN INDIVIDUALS WITH KINESIOPHOBIA POST-ACLR

M. Braatz, W. Smith, J. Zhang. C.J. Wutzke Gonzaga University, Spokane, WA Anterior cruciate ligament (ACL) tears are common in active individuals with altered gait characteristics post ACL reconstruction. Compensatory movements such as greater loading rate of the contralateral knee and increased stiffness of affected knee occur following ACLR. Fear of reinjury (kinesiophobia) can cause changes in movement with compensatory muscle activation, however, the association between kinesiophobia and gait deviations is unclear. PURPOSE: To determine the influence of kinesiophobia on ground reaction force and knee kinematics in ACLR individuals. METHODS: Six individuals with surgically repaired ACL between 6 months and 3 years prior completed the Tampa Scale for Kinesiophobia (TSK) and the Tegner Activity Scale (TAS) to determine classification of kinesiophobia. A seven inertial sensor system were fitted to the lower extremities of participants. Following a dynamic warm-up of 5 minutes of walking at a self-selected pace (SPP) on the split-belt instrumented treadmill, participants completed a three-minute walking trial for SSP, 25% slower than SSP (SP) and 25% faster than SSP (FP) with a break between each trial. TSK and TAS scores were recorded as well as kinetic and kinematic data of the lower extremity. Repeated measures ANOVA was conducted to compare the kinetics and kinematics between the injured and healthy leg, and across different walking paces with an alpha value p\u3c 0.05. Spearman’s rho correlational analysis was conducted to determine associations between TSK and time since surgery. RESULTS: A difference between maximum knee flexion/extension between SP (56.28±4.18) and SSP (59.70±3.21) approached significant (p=0.063). Differences in vertical loading rate (SP =17.48±1.91, SSP=22.65±.97, FP= 27.65±3.30, p=0.010), peak propulsion force (SP=0.06±0.02, SSP=0.05±0.01, FP=0.16±0.03, p\u3c0.001), peak braking force (SP = 0.37±0.02, SSP=0.46±0.03, FP=0.38±0.05, p=0.039) were found across different walking paces. A negative correlation between score on TSK (39.8±3.8) and time since surgery (15.7±8.2 months) was found (r(4)=-0.90, p=0.015). CONCLUSIONS: Individuals showed no difference between legs for kinematic or GRFs, despite high rate of kinesiophobia. People may be reclaiming function in injured knees at a faster rate than they regain confidence

THE EFFECT OF DUAL MOTOR TASK ON LEG EXTENSION MAX FORCE OUTPUT

J. Rutherford, M. Ravitz, C. Ito, B. Farber, C. Motes Vela, C.J. Wutzke Gonzaga University Spokane, WA The ability to split attentional demands is important for a variety of everyday tasks, however this is of particular importance during athletic competition. Although it is understood that dual tasking is associated with impaired motor performance, it is not known if different sources of dual task attentional demands alter motor performance differently. PURPOSE: To determine the influence of visual, cognitive, motor, and mixed motor tasks on peak torque, time to peak torque, and average torque during a maximal isometric leg extension. METHODS: 12 young, unimpaired adult participants completed maximal isometric leg extensions for 3 seconds under different conditions of dual task: a gross motor (MOT) task, a visual (VIS) task, a cognitive (COG) task, and a task combining the three (COMBO). For each condition, torque production was recorded using a HUMAC isokinetic dynamometer. Data was analyzed using a repeated measures ANOVA to determine differences between conditions (p\u3c0.05). RESULTS: Baseline peak torque (75.40+19.84Nm) was lower than dual task conditions including the MOT task (66.17+23.50 Nm, p=0.007), the VIS task (68.08+21.39 Nm, p=0.003), the COG task (63.92+22.69 Nm, p=0.007), and COMBO task (58.96+24.75 Nm, p\u3c0.001). Average torque at during conditions of dual task (MOT 50.21+19.11 Nm, p\u3c.001; COG 52.86+20.17 Nm, p=.006; COMBO task 47.42+21.78 Nm, p\u3c.001) were lower than baseline average torque (62.08+15.80 Nm). No differences were found in time to peak torque between baseline and conditions of dual task. CONCLUSIONS: Conditions of dual task was associated with reduced torque production compared to baseline condition. Motor and cognitive dual task conditions influenced torque production moreso than the visual dual task condition. Torque production (peak and average torque) was most influenced by the combination dual task condition suggesting that as attentional task demands increased, participants prioritized performance on non-motor tasks to the detriment of motor performance. Future research should examine the influence training with conditions of dual task to determine if motor performance can be maintained when exposed to dual attentional demands

INFLUENCE OF HIP EXERCISE ON GROUND REACTION FORCES DURING SINGLE LEG DROP TEST

H. Peterson, A. Halstead, L. Kleiner, B. Miller, A. Strickland, E. Hollingsworth, C.J. Wutzke Gonzaga University, Spokane, WA Anterior cruciate ligament (ACL) tears are a leading knee injury in athletes, often occurring when fatigued. Fatigue increases risk for injury as control of lower limbs is compromised and may lead to biomechanical disadvantages at the knee as adductors and abductors reduce load in the medial lateral compartment of the knee. Single-leg drop tests assess knee stability and strength during plyometric movements and are common in rehab settings post ACL tear. A drop test onto a force plate allows for analysis of ground reaction forces (GRF) to determine magnitude of forces and loading patterns during a landing. PURPOSE: To determine the influence of the frontal plane hip exercise on GRFs during a single leg drop test in unimpaired young adults. METHODS: Participants (n=11) completed two sessions that included single leg drops from a 20 cm tall box onto a force plate. Participants exercised dominant limb hip abductors and adductors separately during individual sessions using an isokinetic dynamometer. Hip adductors and abductors were isometrically activated maximally until torque output was less than 50% of individual peak torque. Once torque was less than 50%, three single-leg drop tests were completed. Participants returned within 10 days for second session. Components of vertical ground reaction force including acceptance slope, absorption slope, balance slope, and mediolateral force range were calculated. Data was analyzed using a repeated measures ANOVA to determine influence due to exercise and between muscles. RESULTS: Abductors demonstrated greater mediolateral range (PRE: 194.9±40.6N, POST: 185.4±83.3N) compared to adductors (PRE:150.1±63.8N, POST: 136.7±51.8N, p=0.006). Adductor absorption slope magnitude increased post exercise (PRE: -7191±2258.1N, POST: -8353±3476.2N) while abductor absorption slope magnitude decreased post exercise (PRE: -8210±2845.80N, Post: -7173±3667.10N, p=0.020). Peak vertical force of the hip adductors increased after exercise (PRE: 2301±649.9N, POST: 2413±673.7N) while peak vertical force of abductors decreased after exercise (PRE: -2512.3±625.4N, POST: -2241.4±711.4N, p=0.014). CONCLUSION: Hip adductors contribute to absorption of vertical GRF moreso than hip abductors although abductors may influence mediolateral stability

THE INFLUENCE OF AUDITORY STIMULI ON MOVEMENT REACTION TIME

G. Riva, M. Atkins, M. Ellingsen, H. Randhawa, E. Stiffler, D. Young, C.J. Wutzke Gonzaga University, Spokane, WA Listening to music while performing tasks such as driving or exercising is common and research suggests classical or heavy metal music can improve reaction time (RT) on cognitive performance tasks; although the neural mechanisms are not understood. Music tempo can affect human cognition, diet, and driving behaviors, but there is minimal research about the impacts of tempo on RT. PURPOSE: To compare choice RT between high tempo (H), low tempo (L), and silent (S) auditory conditions in the upper and lower extremity (dominant and nondominant limbs) in unimpaired, young adults. METHODS: 20 participants performed 18 RT trials—9 upper extremity (UE) and 9 lower extremity (LE) trials respectively—using an app-based light reflex training system. Each trial consisted of 10 randomized lights with participants contacting the light either with the dominant (D) or nondominant (N) limb depending on the color of the light. Participants’ RT was measured from when the light was illuminated to the time when participant contacted the light. Statistical analyses included 3x2x2 repeated measures ANOVAs to examine RT and variance in RT with an alpha value of p≤0.05. RESULTS: Participants’ RT was measured in 6 conditions (H/UE: 656 ± 114ms, H/LE: 877 ± 138ms, L/UE: 667 ± 106ms, L/LE: 874 ± 134ms, S/UE: 676 ± 133ms, and S/LE: 901 ± 137ms). RT was slower in the lower extremity than upper extremity (F(1,18)=195.869, p\u3c 0.001). There was no difference in RT between the different music tempos (F(2,36)=1.519, p=0.233), or between limb dominance (F(1,18)=1.089, p=0.310). There were no interaction effects and no difference in variance across conditions. Across all participants, there was 99.97% accuracy in choice RT. CONCLUSION: RT is slower in the lower extremity, potentially due to postural control considerations and less LE experience responding to “left” and “right” commands. Tempo has no effect on RT, which indicates participants may have tuned out the music and/or the cognitive load was too low. Limb dominance likewise has no effect on choice RT. Participants seemed to prioritize accuracy over speed with one error during all trials completed. Further research is needed to examine how different populations may respond to this procedure, how choice RT is affected by a greater cognitive load or familiar music

THE INFLUENCE OF REDUCED TEMPERATURE ON TORQUE PRODUCTION

S. Castro, T. Kitchel, L. Fortner, M. McCallum, J. Rivera Perez, C.J. Wutzke Gonzaga University, Spokane, WA Collegiate outdoor athletes tend to come from warmer climates compared to colder climates. This is due to the warmer climate athletes having the ability to practice year-round in their respective sports. Environmental conditions (increased temperature) have also shown to influence performance including torque production. In contrast, little is known regarding the influence of cooler temperatures and their influence on exercise performance. Previous literature has focused on how reduced temperature conditions can negatively influence the cardiovascular system and muscular physiology. PURPOSE: To determine if exercise in a reduced temperature influences peak and absolute max torque production of the biceps brachii and the semimembranosus. METHODS: This study examined 13 young, unimpaired adults (x=21.9±2.2 years) who were regularly active. Participants completed a standard stretching warm-up at room temperature (20°C) and in a reduced temperature (3.3°C) condition consisting of a two-and-a-half-minute walk (3mph) and a one-minute run (7mph). Following the warmup, participants completed five repetitions of bicep and hamstring curls respectively. Data analysis was conducted using repeated ANOVA to analyze dynamometer data between reduced and room temperature conditions with an alpha level of p≤0.05. RESULTS: Max torque in the reduced temperature of the biceps brachii (47.77 ± 19.68 Nm) showed no difference in comparison to that of the room temperature condition (45.18±18.57 Nm, p=0.08). Similarly, no difference was found in max torque in the semimembranosus (90.69±32.51 Nm reduced temperature; 94.02±34.67 Nm room temperature; p=0.68). Similarly, for peak torque of the biceps brachii, there was no difference between the reduced temperature condition (0.54±0.15) and the room temperature condition (0.51±0.14, p=0.18). A similar result was found for the peak torque of the semimembranosus. CONCLUSIONS: Our findings suggest that torque production for both the biceps brachii and semimembranosus does not differ during acute exposure to a reduced temperature condition. Additional study is necessary to determine the influence of repeated exposure to environmental conditions on torque production