Rectus Femoris Activity Research Articles

Effects of Running on Sand vs. Stable Ground on Kinetics and Muscle Activities in Individuals With Over-Pronated Feet.

Background: In terms of physiological and biomechanical characteristics, over-pronation of the feet has been associated with distinct muscle recruitment patterns and ground reaction forces during running.Objective: The aim of this study was to evaluate the effects of running on sand vs. stable ground on ground-reaction-forces (GRFs) and electromyographic (EMG) activity of lower limb muscles in individuals with over-pronated feet (OPF) compared with healthy controls.Methods: Thirty-three OPF individuals and 33 controls ran at preferred speed and in randomized-order over level-ground and sand. A force-plate was embedded in an 18-m runway to collect GRFs. Muscle activities were recorded using an EMG-system. Data were adjusted for surface-related differences in running speed.Results: Running on sand resulted in lower speed compared with stable ground running (p < 0.001; d = 0.83). Results demonstrated that running on sand produced higher tibialis anterior activity (p = 0.024; d = 0.28). Also, findings indicated larger loading rates (p = 0.004; d = 0.72) and greater vastus medialis (p < 0.001; d = 0.89) and rectus femoris (p = 0.001; d = 0.61) activities in OPF individuals. Controls but not OPF showed significantly lower gluteus-medius activity (p = 0.022; d = 0.63) when running on sand.Conclusion: Running on sand resulted in lower running speed and higher tibialis anterior activity during the loading phase. This may indicate alterations in neuromuscular demands in the distal part of the lower limbs when running on sand. In OPF individuals, higher loading rates together with greater quadriceps activity may constitute a proximal compensatory mechanism for distal surface instability.

Effect of soft tissue manipulation of popliteus muscle on quadriceps muscle activity and torque production in athletes with anterior knee pain

Abstract Study aim: Popliteus is majorly associated with posterior knee pain; however, this muscle can also have an impact on anterior knee pain. The purpose of this study was to determine the effect of soft tissue manipulation of popliteus muscle on non-traumatic anterior knee pain in athletes; as the relationship between popliteus and Quadriceps muscle has not been studied/explored much. Materials and methods: In this experimental study, 15 subjects presenting with non-traumatic anterior knee pain were selected. Quadriceps muscle activity, torque production and knee pain were assessed. Followed by a single session of popliteus manipulation all the above parameters were re-assessed immediately and at 24 hours after intervention. Results: Significant reduction in pain (P &lt; 0.005) at 24 hours was observed. There was a significant increase in muscle activity of Vastus Medialis (P &lt; 0.05) and Vastus Lateralis (P &lt; 0.005) immediately after the intervention but not after 24 hours. No significant change was found in the activity of Rectus femoris and Peak torque of Quadriceps immediately after the intervention and at 24 hours. Conclusion: Soft tissue manipulation decreased knee pain and improved muscle activity. Therefore, incorporating popliteus manipulation can be effective in treatment of anterior knee pain.

Force Myography計測を利用した繰り返しを伴う屈伸動作時における下肢部の筋活動評価

Evaluations of muscle activities are important in the studies of motion analysis as human performance surveys. Force-myography (FMG), which has proposed as a similar objective to electromyography (EMG), has been applied in motion analysis focusing on the muscular activities. In this study, the usefulness of FMG for physical load measurements in repeated self-weight training was investigated in comparison with EMG. The muscle activities of the right rectus femoris were measured by each method when the subjects performed several patterns of squat motions. It was found that the intensity of muscle activity increased with increasing the load. In addition, when using the pressure sensing FMG devices, the effect of pumping up due to overuse of muscles was also found during the squat motion. By using FMG measurements, there is a possibility to evaluate conveniently the muscle activity during bodyweight training.

Change in the activity of trunk and lower limb muscles during 2000-m rowing.

This study aimed to clarify the changes in the activity of the trunk and lower limb muscles during 2000-m rowing. Ten male rowers performed a 2000-m race simulation on a rowing ergometer. Electromyography results of the abdominal muscles, back muscles, gluteus maximus (GMax), biceps femoris (BF), and rectus femoris (RF) were recorded. The electromyographic activity during the three strokes after the start (initial stage), at 1000m (middle stage), and before the end (final stage) were analyzed. From the handle position, the rowing motion was divided into five phases (early-drive, middle-drive, late-drive, early-recovery, and late-recovery). The peak activities of the abdominal muscles, back muscles, GMax, and BF in each stroke of the rowing motion were delayed at the middle and final stages compared to the initial stage (P<0.05). The peak activity of the RF was observed in the late-drive phase at the initial stage, whereas a high RF activity was observed in the middle-drive phase at the middle and final stages (P<0.05). Considering the results of the activity of the back muscles and RF, RF muscular endurance enhancement may lead to a decrease in the load on the back muscles and help prevent muscular low back pain in rowers. J. Med. Invest. 69 : 45-50, February, 2022.

Gait changes following robot-assisted gait training in children with cerebral palsy.

This study investigated changes of gait pattern induced by a 4-week robot-assisted gait training (RAGT) in twelve ambulatory spastic diparesis children with cerebral palsy (CP) aged 10.4+/-3.2 years old by using computerized gait analysis (CGA). Pre-post intervention CGA data of children with CP was contrasted to the normative data of typically developing children by using cross-correlation and statistically evaluated by a Wilcoxon test. Significant pre-post intervention changes (p<0.01) include: decreased muscle activity of biceps femoris, rectus femoris, and tibialis anterior; a decrease in range of internal hip joint rotation, higher cadence, step length, and increased stride time. This study suggests that RAGT can be used in muscle reeducation and improved hip joint motion range in ambulatory children with CP.

108배와 버피테스트 동작 시 근활성도 단순 비교

Previous studies of 108 bows and Burpee test exercises have reported effective exercise for improving physical fitness and strength. However, scientific and quantitative studies of muscles that are activated during both movements are inadequate. Therefore, in this study, 22 adults were classified into the 108 bows population(A) and the burpee test population(B). The purpose is to compare the difference with the change in muscle activity of each movement, compare accurate data, and present an effective practice method.BR The results of this study are as follows. First, the comparison results of the muscle activity of Rectus Abdominis showed high muscle activity in all the buffy tests on the left and right, and a statistically significant difference between the two populations was observed in the comparison of the muscle activity of the right side Bokujikugun (p.05). Second, the comparison results of the muscle activity of Rectus Femoris The muscle activity of both buffy tests appeared high, and there was a statistically significant difference between the two populations on both the right side (p.001) and the left side (p.01).

Muscle co-contraction and pre-activation in knee and ankle joint during a typical Tai Chi brush-knee twist-step

ABSTRACT This study aimed to investigate the co-contraction and pre-activation of agonistic and antagonistic muscles in experienced Tai Chi (TC) practitioners during normal walking (NW) and brush-knee twist-step (BKTS). The electromyographic activities of rectus femoris, biceps femoris, and tibialis anterior and lateral gastrocnemius muscles were collected during BKTS and NW in 28 TC practitioners. The pre-activation of knee and ankle joints before initial landing of left foot, and the co-contraction of knee and ankle joint in double-stance phase I (DSI), single-stance phase (SS), double-stance phase II (DSII), and swing phase (SW) were calculated during BKTS and NW. Ankle co-contraction significantly increased during DSI and SS in BKTS movements than compared with that in NW. For DSI and SW, SS and DSII, and DSII and SW, a significant difference was found in BKTS. The pre-activation of knee joint significantly decreased in BKTS and NW. This study indicated greater ankle joint muscle co-contraction in DSI and SS of stance phase and lower knee joint muscle co-contraction and pre-activation than in NW in BKTS movement. In addition, greater ankle joint muscle co-contraction was observed in the DSI, SS, and DSII of stance phase than those of swing phase in BKTS movement.

Integrated Physiological, Biomechanical, and Subjective Responses for the Selection of Assistive Level in Pedelec Cycling.

In recent decade, pedelec has become one of the most popular transportation modes due to its effectiveness in reducing physical effort. The effects of using pedelec as an alternative mode of exercise were explored in previous studies. However, the effects of pedelec parameters were not quantified for the self-selected gear ratio, random riding speed, and varied road slopes, which restricted its application. Hence, this study aimed to evaluate the effects of gear ratio and assistive torque and to determine the optimum riding condition regarding physiological, biomechanical, and subjective responses of the rider. The riding tests consisted of simulated slope (1.0 vs. 2.5% grade), gear ratio (light vs. heavy), and assistive levels (0.5, 1, 1.5, and 2), and the tests were conducted in a randomized order. A total of 19 non-athletes completed the riding tests to evaluate physiological [metabolic equivalent of task (MET), heart rate, and gross efficiency (GE)], biomechanical [muscle activity (expressed as reference voluntary contraction, RVC) and power output], and subjective responses [rating of perceived exertion (RPE) and sense of comfort (SC)]. The test conditions induced moderate to vigorous intensities (3.7–7.4 METs, 58.5–80.3% of maximal heart rate, 11.1–29.5% of RVC rectus femoris activity, and 9.4–14.2 RPEs). The effects of gear ratio and assistive level on the physiological responses were significant. Riding with the heavy gear ratio showed advantages in METs and GE. For the optimum assistive level selection, low GE and limited improvement in subjective responses suggested the impact of low-power output conditions. Overall, for the health pedelec commuters, riding with 0.75 W/kg power output with 50 rpm cadence is recommended to obtain the moderate intensity (4.7 METs) and the advantages in GE and subjective feelings. Moreover, the findings can be applied to exercise intensity control and save battery energy effectively in varying riding conditions.

Does the Duncan-Ely test predict abnormal activity of the rectus femoris in stroke survivors with a stiff knee gait?

ObjectiveTo determine the diagnostic value of the Duncan-Ely test in predicting abnormal rectus femoris activity during gait in stroke survivors walking with a stiff knee gait.DesignCross-sectional diagnostic study.SubjectsA total of 95 patients with chronic stroke.MethodsDuring physical examination, the Duncan- Ely test was performed and scored. Surface electromyography of the rectus femoris was then recorded during dynamic gait. To determine the diagnostic value, the results of the Duncan-Ely test and surface electromyography recordings (gold standard) were compared.ResultsThe Duncan-Ely test had a sensitivity of 73%, a specificity of 29%, a positive predictive value of 60%, and a negative predictive value of 42%. The area under the curve was 0.488 (95% CI 0.355– 0.621, p = 0.862), showing that the Duncan-Ely test is not better than random guessing.ConclusionThe Duncan-Ely test has no predictive value for determining abnormal activity of the rectus femoris during gait. Using this test can lead to incorrect identification of abnormal rectus femoris activity, which might hamper the selection of optimal treatment options. We recommend stopping use of the Duncan-Ely test to predict rectus femoris overactivity during swing, and instead use surface electromyography.LAY ABSTRACTAfter stroke, some patients have difficulty bending their knee when they swing their leg forwards. This can be the result of the rectus femoris muscle being too active. It is important to know whether this is the case. If the rectus femoris is too active, we can select a treatment option that aims to reduce its activity. Healthcare professionals often use the Duncan-Ely test, to test for overactivity of the rectus femoris. However, it is not known whether this test is reliable. This study therefore compared the Duncan-Ely test with a measurement in which the activity of the rectus femoris was recorded during walking. No correlation was found between the score of the Duncan-Ely test and the activity of the rectus femoris during walking. We conclude that healthcare professionals should no longer use the Duncan-Ely test to assess overactivity of the rectus femoris, but should replace it with surface electromyography.

Hip muscle activity in male football players with hip-related pain; a comparison with asymptomatic controls during walking

ObjectivesCompare muscle activity between male football players with and without hip-related pain. Morphological and intra-articular features of hip-related pain are proposed pre-cursors to hip osteoarthritis. Altered muscle activity is a feature of severe hip osteoarthritis, but it is not known whether differences exist earlier in the pathological spectrum. DesignCross-sectional; SettingUniversity laboratory; ParticipantsForty-two male football players with hip-related pain; and 19 asymptomatic controls. Main outcome measuresHip muscle activity (Gluteus maximus, gluteus medius, tensor facia latae, adductor longus and rectus femoris) was recorded during walking using surface electromyography (EMG). ResultsMen with hip-related pain had sustained rectus femoris activity prior to toe-off (47–51% of the gait cycle) (p = 0.01, ES = 0.51) unlike controls who had reduced activity. In men with severe hip-related pain, gluteus maximus EMG was sustained into mid-stance (12–20% of the gait cycle) (F = 6.15, p < 0.01) compared to controls. ConclusionsDifferences in rectus femoris and gluteus maximus activity were identified between male footballers with and without hip-related pain. The pattern of gluteus maximus EMG relative to peak, approaching mid-stance in severe hip-related pain, is consistent with observations in severe hip osteoarthritis. This supports the hypothesis that symptom severity may influence muscle activity across the spectrum of hip degeneration.

Is the Power Spectrum of Electromyography Signal a Feasible Tool to Estimate Muscle Fiber Composition in Patients with COPD?

A greater proportion of glycolytic muscle fibers is a manifestation of skeletal muscle dysfunction in Chronic Obstructive Pulmonary Disease (COPD). Here, we propose to use the spectral analysis of the electromyographic signal as a non-invasive approach to investigate the fiber muscle composition in COPD. We recorded the electromyographic activity of Rectus Femoris (RF), Vastus Lateralis (VL), Vastus Medialis (VM) and Biceps Femoris (BF) muscles, in ten patients and ten healthy individuals, during non-fatiguing, flexion–extension leg movements. The mean (MNF) and median frequencies (MDF) were calculated, and the most common profiles of electromyographic power spectrum were characterized by using the principal component analysis. Frequency parameters showed higher values in patients with COPD than in the control group for the RF (+25% for MNF; +21% for MNF), VL (+16% for MNF; 16% for MNF) and VM (+22% for MNF; 22% for MNF) muscles during the extension movements and for the BF (+26% for MNF; 34% for MNF) muscle during flexion movements. Spectrum profiles of the COPD patients shifted towards the higher frequencies, and the changes in frequency parameters were correlated with the level of disease severity. This shift of frequencies may indicate an increase in glycolytic muscle fibers in patients with COPD. These results, along with the non-fatigable nature of the motor task and the adoption of a non-invasive method, encourage to use electromyographic spectral analysis for estimating muscle fiber composition in patients with COPD.

Compression Garments Reduce Soft Tissue Vibrations and Muscle Activations during Drop Jumps: An Accelerometry Evaluation.

Objectives: To explore the effects of wearing compression garments on joint mechanics, soft tissue vibration and muscle activities during drop jumps. Methods: Twelve healthy male athletes were recruited to execute drop jumps from heights of 30, 45 and 60 cm whilst wearing compression shorts (CS) and control shorts (CON). Sagittal plane kinematics, ground reaction forces, accelerations of the quadriceps femoris (QF), hamstrings (HM) and shoe heel-cup, and electromyography images of the rectus femoris (RF) and biceps femoris (BF) were collected. Results: Compared with wearing CON, wearing CS significantly reduced the QF peak acceleration at 45 and 60 cm and the HM peak acceleration at 30 cm. Wearing CS significantly increased the damping coefficient for QF and HM at 60 cm compared with wearing CON. Moreover, the peak transmissibility when wearing CS was significantly lower than that when wearing CON for all soft tissue compartments and heights, except for QF at 30 cm. Wearing CS reduced the RF activity during the pre-, post-, and eccentric activations for all heights and concentric activations at 45 cm; it also reduced the BF activity during post- and eccentric activations at 30 and 60 cm, respectively. The hip and knee joint moments and power or jump height were unaffected by the garment type. Conclusion: Applying external compression can reduce soft tissue vibrations without compromising neuromuscular performance during strenuous physical activities that involve exposure to impact-induced vibrations.

Kinematic and Electrophysiological Characteristics of Pedal Operation by Elderly Drivers during Emergency Braking

Age-related decline in lower limb motor control may cause errors in pedal operation when driving a car. This study aimed to clarify the kinematics and electrophysiological characteristics of the pedal-switching operation associated with emergency braking in the case of elderly drivers. The participants in this study consisted of 11 young drivers and 10 elderly drivers. An experimental pedal was used, and the muscle activity and kinematic data during braking action were analyzed using the light from a light-emitting diode installed in the front as a trigger. The results showed that elderly drivers took the same time from viewing the visual stimulus to releasing the accelerator pedal as younger drivers, but took longer to switch to the brake pedal. The elderly drivers had higher soleus muscle activity throughout the process, from accelerator release to brake contact; furthermore, the rectus femoris activity was delayed, and the simultaneous activity between the rectus femoris and biceps femoris was low. Furthermore, elderly drivers tended to have low hip adduction velocity and tended to switch pedals by hip internal rotation. Thus, the alteration in joint movements and muscle activity of elderly drivers can reduce their pedal operability and may be related to the occurrence of pedal errors.

Characteristics of rectus femoris activation and rectus femoris-hamstrings coactivation during force-matching isometric knee extension in subacute stroke.

The spectral properties of surface electromyographic (EMG) signal in the rectus femoris (RF) and the coactivation in the medial hamstrings (MH) were investigated in 45 stroke subjects (22 ± 12days post-onset) and 30 age-matched healthy controls who performed unilateral knee extensions at maximum effort (100% MVC) and during 5-s force-matching tasks (10, 30, 50% MVC). The spectral properties were obtained through a power spectrum analysis based on Fast Fourier Transform. The coactivation was measured as the MH amplitude (%max) and MH/RF amplitude ratio. Force variability was expressed as the coefficient of variation. Both knee extensors and flexors were weaker in the paretic leg than the non-paretic and control legs (p < 0.001). A significantly higher relative power in the 5-13 and 13-30Hz bands was found in the paretic than the non-paretic leg across all force levels (p ≤ 0.001) without changes in the 30-60 and 60-100Hz bands or the mean and median frequencies. Regarding the antagonist coactivation, MH amplitude in the paretic leg was higher than in the non-paretic leg (submaximal levels, p < 0.0001) and the control leg (all force levels, p = 0.0005) with no differences between legs in the MH/RF ratio. The steadiness of the knee extension force was not related to the spectral properties of the agonist EMG or antagonistic coactivation. Greater coactivation was associated with weaker paretic knee flexors (p ≤ 0.0002). The overall results suggest variably altered agonist activation and antagonistic coactivation over the range of isometric knee extension contractions in subacute stroke.

The effect of powered ankle prostheses on muscle activity during walking

Individuals with transtibial amputation (TTA) walk with greater muscle activity and metabolic costs than non-amputees. Powered prostheses aim to address these deficits by replicating the active function of the biological ankle. The purpose of this study was to determine if people with TTA alter muscle activity when walking with a powered prosthesis, and if this change relates to changes in metabolic costs. Ten individuals with TTA and 10 non-amputees walked on a treadmill while we measured metabolic cost and muscle activity from 16 lower limb muscles. Participants with TTA walked with their prescribed unpowered prosthesis and a commercial powered prosthesis (BiOM T2, Bedford, MA, USA), in random order. The integrated EMG across the gait cycle was greater with the powered prosthesis for the intact limb gluteus medius (p = 0.002) and residual limb vastus medialis (p = 0.013). There were several non-significant, moderate-to-strong correlations between changes in muscle activity and changes in metabolic cost between prostheses (p > 0.0504). Decreased muscle activity in the residual limb gluteus medius correlated with lower metabolic cost (r = 0.543). In contrast, lower metabolic cost was correlated with increased residual limb rectus femoris activity (r = -0.627) and increased co-contractions in the residual limb thigh muscles in terminal stance (r = -0.585) and late swing (r = -0.754). Overall, there were no consistent changes in muscle activity in response to the powered prosthesis. The correlations suggest that individuals who can effectively stabilize their residual limb during stance are more likely to benefit metabolically.

Lower limb muscle activation during outdoor running: differences between sprinters, middle-distance and long-distance runners

ABSTRACT Running is one of the most popular sport practices in the world. However, to our knowledge, none of the previous research about the characteristics of outdoor running makes a distinction between the different modalities of runners. Sixty-five healthy runners classified in sprinters, middle distance and long-distance runners performed five series of 100 metres on the synthetic outdoor track at competition pace. Muscle activity of lower limb muscles at initial contact and toe-off, involving the gluteus medius (GMED), gluteus maximus (GMAX), biceps femoris (BF), rectus femoris (RF), tiabilis anterior (TA) and medial gastrocnemius (MGAS), and spatiotemporal parameters were analysed. Sprinters showed high percentages of muscle activity at initial contact, in particular, the TA activity was the highest. The RF activity was significantly the lowest activity registered. At toe-off, sprinters showed the highest activity in all muscles analysed. Middle-distance runners had the highest activity of GMAX, BF and MGAS during the initial contact. In long-distance runners, the GMED and RF activity during the initial contact is highlighted, showing the highest activity of this phase. Different patterns of lower limb muscle activity and spatiotemporal parameters exist depending on the modality of the runner.

Analysis of Muscle Activity During Shooting Motion of Korean Traditional Archers

The past few decades has seen increasing kinematic studies using surface electoromyography (EMG) in archery, however there has been no such specific study in Korean traditional archery. The purpose of this study was to evaluate EMGs during archery shooting motion in Korean traditional archers. Ten men Korean traditional archers were participated, and divided into two groups according to the shooting stance; parallel stance group(PSG, n=5) and oblique stance group(OSG, n=5). The surface EMGs were measured 12 muscles during shooting motion of five events including Junbi(Set), Geogung(Set up), Manjak(Full draw), Balsi(Release), Machigi(Ending). At the result, muscle activity of posterior deltoid, trapezius, rhomboid major, latissimus dorsi, biceps brachii, forearm extensor bundle, triceps brachii, levator scapulae significantly increased at event of full draw and release, then significantly decreased again at event of ending, respectively(p&lt;.01, p&lt;.001). The muscle activity of erector spinae(ES) was also significantly increased at event of full draw and release(p&lt;.01, p&lt;.001), while no significant changes in muscles of rectus abdominis, rectus femoris(RF), gluteus maximus. As a result of comparing PSG and OSG, muscle activity of RF in OSG was higher than PSG at event of release(p&lt;.05), it remained until event of ending(p&lt;.05). On the other hand, the higher the tension of the bow, the higher the muscle activity of the draw arm at event of release(p&lt;.05). These results suggest that when Korean traditional archery shooting, both side arm and back muscles are more activated than the abdomen, leg and hip muscles. The parallel stance might suppress the muscle activity of the lower extremities to twist the upper body. And the higher bowstring tension needs to increase of muscle strength in BB of draw arm.

Multi-joint biomechanics during sloped walking in patients with developmental dysplasia of the hip

BackgroundDevelopmental dysplasia of the hip is characterized by abnormal acetabular and femoral geometries that alter joint loading and increase the risk of hip osteoarthritis. Current understanding of biomechanics in this population remains isolated to the hip and largely focused on level-ground walking, which may not capture the variable loading conditions that contribute to symptoms and intra-articular damage. MethodsThirty young adult females (15 with dysplasia) underwent gait analysis during level, 10° incline, and 10° decline walking while whole-body kinematics, ground reaction forces, and electromyography (EMG) were recorded. Low back, hip, and knee joint kinematics and internal joint moments were calculated using a 15-segment model and integrated EMG was calculated within the functional phases of gait. Dependent variables (peak joint kinematics, moments, and integrated EMG) were compared across groups with a one-way ANOVA with multiple comparisons controlled for using the Benjamini-Hochberg method (α = 0.05). FindingsDuring level and incline walking, patients with developmental dysplasia of the hip had significantly lower trunk flexion angles, lumbar and knee extensor moments, and erector spinae activity than controls. Patients with developmental dysplasia of the hip also demonstrated reduced rectus femoris activity during loading of level walking and increased gluteus maximus activity during mid-stance of decline walking. InterpretationPatients with developmental dysplasia of the hip adopt compensations both proximal and distal to the hip, which vary depending on the slope of walking. Furthering the understanding of multi-joint biomechanical compensations is important for understanding the mechanism of osteoarthritis development as well as secondary conditions.

Association between Kinesiophobia and Gait Asymmetry after ACL Reconstruction: Implications for Prevention of Reinjury.

Gait asymmetries have been documented in individuals after anterior cruciate ligament (ACL) reconstruction (ACLR). The relationship between gait asymmetry and associated psychological factors, however, is not yet known. This study aimed to examine the relationship between kinesiophobia (fear of reinjury) and asymmetry of vertical ground reaction force (vGRF) and lower-extremity muscular activity in individuals after ACLR during gait. Twenty-eight males with a history of ACLR participated in the study. Force plate and surface electromyography was used to record peak vGRF and muscular activity. The Tampa Scale of Kinesiophobia (TSK-11) was used to measure kinesiophobia. Spearman’s rank correlations analysis was used to examine the relationship between TSK-11 scores and both gait asymmetry variables. There was a significant positive relationship between TSK-11 and asymmetry of the second peak of vGRF (rs = 0.531, p = 0.002). In addition, there was a significant positive association between asymmetry of rectus femoris activity (rs = 0.460, p = 0.007) and biceps femoris activity (rs = 0.429, p = 0.011) in the contact phase. Results revealed a significant relationship between kinesiophobia and asymmetry in muscle activity and vGRF in different phases of the gait cycle. Interventions addressing kinesiophobia early in the rehabilitation after ACLR may support the restoration of gait symmetry, facilitate a more rapid return to sport, and reduce the risk of ACL reinjury.

35991 Towards a Novel Robotic Control Scheme to Improve Lower Extremity Movement Post-Stroke

ABSTRACT IMPACT: Effective robotic pedaling therapy would allow stroke survivors a precision, customized, and adaptable therapy to help recover lower extremity function. OBJECTIVES/GOALS: It has been observed that people post-stroke can pedal each limb individually but not simultaneously when the bicycle is split-crank. This implies that lower extremity movement difficulties are affected more by interlimb rather than unilateral coordination deficits. This work seeks to further develop a robotic split-crank pedaling therapy device. METHODS/STUDY POPULATION: This work uses a robotic split-crank pedaling device to facilitate rehabilitation of interlimb coordination, measured by continuous relative phase (CRP) and paretic neuromuscular output. The effects of three control schemes were tested: assist, resist, and assist+resist. Each limb was strapped to a pedal which was connected to a motor. The participants were asked to pedal forward while keeping the pedals antiphase. The robot aided or resisted according to the activated control scheme. Control schemes were tested on two stroke participants. The control schemes respond proportionally to phasing deviation from 180 degrees. The assist scheme assisted the lagging limb while the resist scheme resisted the leading limb. The assist+resist did both control actions. RESULTS/ANTICIPATED RESULTS: For the assist scheme, CRP improved for participant 1 (P1) and declined for participant 2 (P2). P1 increased paretic velocity while P2 decreased. Rectus Femoris (RF) and Biceps Femoris (BF) activity of both limbs lowered for P1. RF and BF activity of both limbs remained about the same but shifted for P2. For the resist scheme, CRP improved for P1 and declined for P2. P1 increased paretic velocity while P2 decreased. P1 increased BF activity of both limbs while RF activity remained constant. P2 increased paretic BF activity and non-paretic RF activity. For the assist+resist scheme, CRP improved for both participants. Both participants increased paretic velocity. P1 increased paretic BF activity and decreased RF activity. P2 better modulated paretic BF and RF. DISCUSSION/SIGNIFICANCE OF FINDINGS: All control schemes augmented performance, however the assist+resist scheme showed the most promise in terms of CRP and muscle activity. More participants are needed to determine true effects of each control scheme. The control scheme selected will be the foundation for further improvements such as adaptive control and extrinsic feedback.