scholarly journals The Impact of a Rotating Balance Platform on Leg Neuromuscular Activity in Healthy Young Adults

2021 ◽  
pp. 22
Author(s):  
Keyword(s):  
Muscle Contraction ◽  
Lower Limb ◽  
Repeated Measures ◽  
Muscle Activation ◽  
Time To Peak ◽  
Contraction Duration ◽  
Tracking Tasks ◽  
Balance Rehabilitation ◽  
The Impact ◽  
Balance Board

Balance is a functional activity that must be implemented in every type of rehabilitation for the back and lower extremities’ injury and pathology. With issues in these regions, balance is lessened, requiring exercises that enhance the patient’s stability. Purpose: To determine the impact of activities on a rotating balance platform with tracking tasks for lower limb muscle activation. Method: Twenty-five participants performed seven tasks on a balance board with a fixed middle fulcrum. For each trial, activation of the gastrocnemius and tibialis anterior muscles was recorded using surface electromyography. Upon examination of the EMG data, the following variables were quantified: time to peak muscle activation, time to decay of muscle contraction, and time of muscle contraction duration. Results: A repeated measures ANOVA revealed that TA exhibited significant modifications (P<0.001) with less time to peak, duration, and decay, whereas GA only notably compensated (P<0.001) with shorter duration and decay. Conclusion: For subjects with balance alterations due to slower nerve conduction or muscle weakness in the lower limb, we suggest incorporating activities with rotational movements on the balance board, where muscle activation is challenged due to surface and tracking activities. When endurance is prescribed, front-to-back tasks contribute to prolonged muscle activation. Balance rehabilitation should consider muscle activation timing with tracking tasks for more precise and targeted muscle execution.

scholarly journals Effects of active muscle forces on driver’s lower-limb injuries due to emergency brake in various frontal impacts

2019 ◽  
Vol 234 (7) ◽  
pp. 2014-2024
Author(s):  
Fan Li ◽  
Wei Huang ◽  
Xingsheng Wang ◽  
Xiaojiang Lv ◽  
Fuhao Mo
Keyword(s):  
Muscle Contraction ◽  
Lower Limb ◽  
Injury Risk ◽  
Muscle Activation ◽  
Bending Moment ◽  
Lower Limbs ◽  
Lower Limb Injuries ◽  
Lower Limb Injury ◽  
Limb Injuries ◽  
The Impact

Accident data shows that driver’s kinematics response in real accidents can be significantly different from that in dummy or cadaver tests because of driver’s muscle contraction. In this study, a finite element human-body model consisting of an upper body of a dummy model and a lower limb–pelvis biomechanical model with three-dimensional active muscles was developed to investigate in depth the lower-limb injuries. Driver’s emergency reaction during frontal impact was simulated by modelling muscle active contraction based on a series of volunteer experimental tests. Besides, a realistic impact environment with the response of the restraint system and the invasion of the driver’s compartment was established in this study. The results show that muscle contraction can cause extra loads on lower limbs during the impact, which can increase the injury risk of lower limbs. As for the femur injury, muscle contraction caused an additional 1 kN axial load on the femur, and the femur resultant bending moment of active models was also higher by about 10–40 N m. Besides, the tibial index of the model with muscle activation was about 0.1 higher. In addition, the results indicate that the femur injury is strongly related to the combined action of both axial force and bending moment. The variation of the injury tolerance along the tibia shaft should be considered when evaluating the tibia injury. Overall, the current lower-limb injury criteria can be still the lack of robustness.

scholarly journals Lower Limb Muscle Activity Adjustment and Lactate Variation in Response to Increased Speed with Proportional Resistance in Young Adults

2021 ◽  
pp. 18
Author(s):  
◽  
Keyword(s):  
Young Adults ◽  
Lower Limb ◽  
Repeated Measures ◽  
Muscle Activation ◽  
Lower Limb Muscle ◽  
Limb Muscle ◽  
Small Load ◽  
Lactate Levels ◽  
Therapy Interventions ◽  
The Impact

Background: Various pathologies require physiotherapists to adjust therapy interventions, some of which are to reducing joint loads while strengthening the lower extremity musculature. Tools such as a sled can be used to accomplish a small load with high-repetition-resistance exercises. Purpose: This study examined the impact of pushing a sled with regulated resistance on lower limb muscle activation and fatigue while walking and running. Methods: The neuromuscular activity of the tibialis anterior (TA) and gastrocnemius (GA) muscles of thirty-six young adults were recorded using surface electromyography (EMG) and lactate data from a Nova Biomedical Lactate Plus meter. The sled used was the XPO Trainer, which maintains a steady resistance proportional to the user regardless of the forces applied to accelerate the sled. Baseline lactate was collected and followed by one of three protocols: run, run-push (RP), or walk-push (WP). Each included three trials over a 40 ft distance, during which EMG data were collected per trial, whereas lactate was collected following the completion of the appointed task. Results: Repeated measures ANOVAs were performed, showing a considerable increase (P<0.05) in lactate levels between the WP and RP groups. Pushing the sled at both WP and RP speeds demonstrated substantial (P<0.05) neuromuscular modifications, primarily in the TA, followed by the GA, in comparison to running. Conclusion: Pushing a constant resistance sled provoked distinct modifications in the lower limb musculature associated with speed. Running while pushing the sled elicits a higher blood lactate response associated with a longer maximal amplitude and a shorter time for muscle recruitment in the GA and TA muscles, all indicative of endurance-oriented exercise.

scholarly journals Role of Occupational Footwear and Prolonged Walking on Lower Extremity Muscle Activation during Maximal Exertions and Postural Stability Tasks

Biomechanics ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 202-213
Author(s):  
Harish Chander ◽  
Sachini N. K. Kodithuwakku Arachchige ◽  
Alana J. Turner ◽  
Reuben F. Burch V ◽  
Adam C. Knight ◽  
...  
Keyword(s):  
Lower Extremity ◽  
Muscle Activity ◽  
Repeated Measures ◽  
Postural Stability ◽  
Muscle Activation ◽  
Medial Gastrocnemius ◽  
Lower Extremity Muscle ◽  
Prolonged Duration ◽  
The Mean ◽  
The Impact

Background: Occupational footwear and a prolonged duration of walking have been previously reported to play a role in maintaining postural stability. The purpose of this paper was to analyze the impact of three types of occupational footwear: the steel-toed work boot (ST), the tactical work boot (TB), and the low-top work shoe (LT) on previously unreported lower extremity muscle activity during postural stability tasks. Methods: Electromyography (EMG) muscle activity was measured from four lower extremity muscles (vastus medialis (VM), medial hamstrings (MH), tibialis anterior (TA), and medial gastrocnemius (MG) during maximal voluntary isometric contractions (MVIC) and during a sensory organization test (SOT) every 30 min over a 4 h simulated workload while wearing ST, TB, and LT footwear. The mean MVIC and the mean and percentage MVIC during each SOT condition from each muscle was analyzed individually using a repeated measures ANOVA at an alpha level of 0.05. Results: Significant differences (p < 0.05) were found for maximal exertions, but this was limited to only the time main effect. No significant differences existed for EMG measures during the SOT. Conclusion: The findings suggest that occupational footwear type does not influence lower extremity muscle activity during both MVIC and SOT. Significantly lower muscle activity during maximal exertions over the course of the 4 h workload was evident, which can be attributed to localized muscular fatigue, but this was not sufficient to impact muscle activity during postural stability tasks.

scholarly journals Characterization of speed adaptation while walking on an omnidirectional treadmill

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Smit Soni ◽  
Anouk Lamontagne
Keyword(s):  
Lower Limb ◽  
Muscle Activation ◽  
Low Cost ◽  
Weight Bearing ◽  
Step Length ◽  
Overground Walking ◽  
Walking Pattern ◽  
Spatiotemporal Parameters ◽  
Walking Speeds ◽  
The Impact

Abstract Background Conventional treadmills are widely used for gait retraining in rehabilitation setting. Their usefulness for training more complex locomotor tasks, however, remains limited given that they do not allow changing the speed nor the direction of walking which are essential walking adaptations for efficient and safe community ambulation. These drawbacks can be addressed by using a self-pace omnidirectional treadmill, as those recently developed by the gaming industry, which allows speed changes and locomotor movements in any direction. The extent to which these treadmills yield a walking pattern that is similar to overground walking, however, is yet to be determined. Methods The objective of this study was to compare spatiotemporal parameters, body kinematics and lower limb muscle activation of healthy young individuals walking at different speeds (slow, comfortable, fast) on a low-cost non-motorized omnidirectional treadmill with and without virtual reality (VR) vs. overground. Results Results obtained from 12 young healthy individuals (18–29 years) showed that participants achieved slower speed on the treadmill compared to overground. On the treadmill, faster walking speeds were achieved by a mere increase in cadence, as opposed to a combined increase in cadence and step length when walking overground. At matched speed, enhanced stance phase knee flexion, reduced late stance ankle plantarflexion, as well as enhanced activation amplitudes of hip extensors in late stance and hip extensors in early swing were observed. The addition of VR to treadmill walking had little or no effect of walking outcomes. Collectively, results show that the omnidirectional treadmill yields a different walking pattern and lead to different adaptations to speed compared to overground walking. We suggest that these alterations are mainly driven by the reduced shear forces between the weight bearing foot and supporting surface and a perceived threat to balance on the omnidirectional treadmill. Conclusion Since such treadmills are likely to be used for prolonged periods of time by gamers or patients undergoing physical rehabilitation, further research should aim at determining the impact of repeated exposure on gait biomechanics and lower limb musculoskeletal integrity.

scholarly journals Adjustments with running speed reveal neuromuscular adaptations during landing associated with high mileage running training

2017 ◽  
Vol 122 (3) ◽  
pp. 653-665 ◽  
Author(s):  
Jasper Verheul ◽  
Adam C. Clansey ◽  
Mark J. Lake
Keyword(s):  
Lower Limb ◽  
Muscle Activation ◽  
Joint Stiffness ◽  
Thigh Muscle ◽  
Running Speed ◽  
Running Training ◽  
Knee Stiffness ◽  
Peak Knee ◽  
The Impact ◽  
Weight Acceptance

It remains to be determined whether running training influences the amplitude of lower limb muscle activations before and during the first half of stance and whether such changes are associated with joint stiffness regulation and usage of stored energy from tendons. Therefore, the aim of this study was to investigate neuromuscular and movement adaptations before and during landing in response to running training across a range of speeds. Two groups of high mileage (HM; >45 km/wk, n = 13) and low mileage (LM; <15 km/wk, n = 13) runners ran at four speeds (2.5–5.5 m/s) while lower limb mechanics and electromyography of the thigh muscles were collected. There were few differences in prelanding activation levels, but HM runners displayed lower activations of the rectus femoris, vastus medialis, and semitendinosus muscles postlanding, and these differences increased with running speed. HM runners also demonstrated higher initial knee stiffness during the impact phase compared with LM runners, which was associated with an earlier peak knee flexion velocity, and both were relatively unchanged by running speed. In contrast, LM runners had higher knee stiffness during the slightly later weight acceptance phase and the disparity was amplified with increases in speed. It was concluded that initial knee joint stiffness might predominantly be governed by tendon stiffness rather than muscular activations before landing. Estimated elastic work about the ankle was found to be higher in the HM runners, which might play a role in reducing weight acceptance phase muscle activation levels and improve muscle activation efficiency with running training. NEW & NOTEWORTHY Although neuromuscular factors play a key role during running, the influence of high mileage training on neuromuscular function has been poorly studied, especially in relation to running speed. This study is the first to demonstrate changes in neuromuscular conditioning with high mileage training, mainly characterized by lower thigh muscle activation after touch down, higher initial knee stiffness, and greater estimates of energy return, with adaptations being increasingly evident at faster running speeds.

scholarly journals Effects of task and hip-abductor fatigue on lower limb alignment and muscle activation

2021 ◽  
Author(s):  
Rodrigo Rabello ◽  
Camila Nodari ◽  
Felipe Scudiero ◽  
Iury Borges ◽  
Luan Fitarelli ◽  
...  
Keyword(s):  
Lower Limb ◽  
Repeated Measures ◽  
Muscle Activation ◽  
Frontal Plane ◽  
Gluteus Medius ◽  
Limb Alignment ◽  
Lower Limb Alignment ◽  
Before And After ◽  
Hip Abduction ◽  
Hip Abductor

Abstract Purpose Fatigue-induced hip-abductor weakness may exacerbate lower-limb misalignments during different dynamic single-leg tasks. We sought to evaluate the effects of fatigue and task on lower limb kinematics and muscle activation and to find associations between measurements obtained in two tasks. Methods One-group pretest–posttest design. Seventeen healthy adults (9 W) performed the single-leg squat (SLSQUAT) and the single-leg hop (SLHOP) before and after a hip-abduction fatigue protocol. Hip adduction, knee frontal plane projection angle (knee FPPA) and heel inversion displacement were measured during the eccentric phase of the SLSQUAT and the SLHOP, as well as activation of the gluteus medius (GMed), tensor fascia latae (TFL), peroneus longus (PER) and tibialis anterior (TA). Moments and tasks were compared using a repeated-measures two-way ANOVA. Correlation between tasks was evaluated using Spearman’s correlation. Results No differences in kinematics or activation were found between moments. Hip-adduction displacement (P = 0.005), GMed (P = 0.008) and PER (P = 0.037) activation were higher during SLSQUAT, while TA activation was higher during SLHOP (P < 0.001). No differences were found between tasks in knee FPPA and heel inversion. Hip-adduction and knee FPPA were not correlated between tasks, while ankle inversion displacement was positively correlated (rs = 0.524–0.746). Conclusion Different characteristics of SLSQUAT (slower and deeper) seem to have led to increased hip adduction displacement, GMed, and PER activation and decreased TA activation, likely due to higher balance requirements. However, hip-abductor fatigue didn’t influence lower-limb alignment during the tasks. Finally, evaluations should be performed with different single-leg tasks since they don’t give the same lower-limb alignment information.

scholarly journals Comparison of foot strike sound between rearfoot, midfoot and forefoot strike runners

2021 ◽  
Author(s):  
Ivan Au ◽  
Leo Ng ◽  
Paul Davey ◽  
Marco So ◽  
Brian Chan ◽  
...  
Keyword(s):  
Gait Analysis ◽  
Lower Limb ◽  
Repeated Measures ◽  
Median Frequency ◽  
Loading Rates ◽  
Vertical Loading ◽  
Foot Strike ◽  
Analysis Laboratory ◽  
Sound Duration ◽  
The Impact

Abstract Context: There are three common foot strike techniques in runners. Whether these techniques generate different sounds at the point of impact with the ground may influence lower limb kinetics. No previous studies have determined whether such relationships exist. Objectives: To determine foot-ground impact sound characteristics and to compare the impact sound characteristics across foot strike techniques and the relationships between impact sound characteristics and vertical loading rates. Design: Cross-sectional study Setting: Gait analysis laboratory Patients or Other Participants: Thirty runners (50% female, age=23.5±4.0 yrs, mass=58.1±8.2kg, height=1.67±0.1m) completed overground running trials with rearfoot strike (RFS), midfoot strike (MFS) and forefoot strike (FFS) techniques in a gait analysis laboratory. Main Outcome Measure(s): Impact sound was measured by a shotgun microphone and the peak sound amplitude, median frequency and sound duration were analysed. Separate linear regression, clustering participants repeated measures were used to compare the sound parameters across foot strike techniques. Kinetic data was collected from a force plate and the vertical loading rates were calculated. Pearson's correlation was used to determine relationship between sound characteristic and kinetics. Results: Landing with a MFS or FFS resulted in greater peak sound amplitude (ps&lt;0.001) and shorter sound duration (ps&lt;0.001) than RFS. MFS exhibited the highest median frequency among the three foot strike patterns, followed by FFS (ps&lt;0.001). We did not find a significant relationship between vertical loading rates and any impact sound parameters (ps&gt;0.115). Conclusions: The results suggest that impact sound characteristics may be used to differentiate foot strike patterns in runners. However, this did not relate to lower limb kinetics. Therefore, clinicians should not solely rely on impact sound to infer impact loading.

Effects of 22 °C muscle temperature on voluntary and evoked muscle properties during and after high-intensity exercise

2007 ◽  
Vol 32 (6) ◽  
pp. 1043-1051 ◽  
Author(s):  
Eric J. Drinkwater ◽  
David G. Behm
Keyword(s):  
High Intensity ◽  
Repeated Measures ◽  
Muscle Activation ◽  
Contractile Properties ◽  
Muscle Temperature ◽  
Plantar Flexors ◽  
Muscle Properties ◽  
Time To Peak ◽  
Cohen’S D ◽  
Cohen's D

The purpose of this study was to investigate the effect of 22 °C local muscle temperature of intact human plantar flexors performing fatiguing contractions on evoked and voluntary contractile properties before and after fatigue. Twelve subjects were tested on plantar flexor voluntary torque, percent muscle activation derived from twitch interpolation, integrated electromyographic (iEMG) activity, and evoked torque and temporal characteristics of maximal twitch and tetanic stimulations before fatigue and 1, 5, and 10 min after intermittent, high-intensity, isometric fatigue under both normothermic and hypothermic conditions. Hypothermic and normothermic changes between time points were analysed by repeated-measures analysis of variance. Normothermic fatigue induced small to large effects (Cohen’s d: 0.29–3.06) on voluntary and evoked contractile properties, whereas most effects of unfatigued hypothermia were limited to rate-dependent processes (Cohen’s d: 0.78–1.70). Most tetanic properties were potentiated 1 min after normothermic fatigue, but remained unchanged by hypothermic fatigue, resulting in significant differences between the two conditions. Soleus iEMG significantly declined 1 min after normothermic fatigue (–29%), but not after hypothermic fatigue. Twitch torque was potentiated by 29% one minute after fatigue while normothermic, but was potentiated by 46% while hypothermic; rate of twitch torque development and time to peak twitch were potentiated by 39% and 10% while normothermic, but 89% and 28% while hypothermic. Although voluntary contractile properties are generally impaired soon after normothermic fatigue, most were not after hypothermic fatigue. Furthermore, evoked contractile properties were generally higher 1 min after hypothermic fatigue. We conclude that the hypothermic condition slows the recovery of potentiated evoked contractile properties back to baseline values.

Hip- and Trunk-Muscle Activation Patterns During Perturbed Gait

2011 ◽  
Vol 20 (3) ◽  
pp. 287-295 ◽  
Author(s):  
Justin M. Stanek ◽  
Todd A. McLoda ◽  
Val J. Csiszer ◽  
A.J. Hansen
Keyword(s):  
Outcome Measures ◽  
Muscle Activity ◽  
Repeated Measures ◽  
Muscle Activation ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Kinetic Chain ◽  
Time To Peak ◽  
Muscle Activation Patterns ◽  
Unexpected Perturbation

Context:Selected muscles in the kinetic chain may help explain the body’s ability to avert injury during unexpected perturbation.Objective:To determine the activation of the ipsilateral rectus femoris (RF), gluteus maximus (MA), gluteus medius (ME), and contralateral external obliques (EO) during normal and perturbed gait.Design:Single-factor, repeated measures.Setting:University research laboratory.Participants:32 physically active, college-age subjects.Intervention:Subjects walked a total of 20 trials the length of a 6.1-m custom runway capable of releasing either side into 30° of unexpected inversion. During 5 trials, the platform released into inversion.Main Outcome Measures:Average, peak, and time to peak EMG were analyzed across the 4 muscles, and comparisons were made between the walking trials and perturbed trials.Results:Significantly higher average and peak muscle activity were noted for the perturbed condition for RF, MA, and EO. Time to peak muscle activity was faster during the perturbed condition for the EO.Conclusion:Rapid contractions of selected postural muscles in the kinetic chain help explain the body’s reaction to unexpected perturbation.

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