THE RELATIONSHIP BETWEEN MUSCULOSKELETAL STRENGTH, PHYSIOLOGICAL CHARACTERISTICS, AND KNEE KINESTHESIA FOLLOWING FATIGUING EXERCISE

Fatiguing exercise may result in impaired functional joint stability and increased risk of unintentional injury. While there are several musculoskeletal and physiological characteristics related to fatigue onset, their relationship with proprioceptive changes following fatigue has not been examined. The purpose of this study was to establish the relationship between musculoskeletal and physiological characteristics and changes in proprioception, measured by threshold to detect passive motion (TTDPM), following fatiguing exercise. Twenty, physically active females participated (age: 28.65 ± 5.6 years, height: 165.6 ± 4.3 cm, weight: 61.8 ± 8.0 kg, BMI: 22.5± 2.3 kg/m2, BF: 23.3 ± 5.4%). During Visit 1, subjects completed an exercise history and 24-hour dietary questionnaire, and body composition, TTDPM familiarization, isokinetic knee strength, and maximal oxygen uptake/lactate threshold assessments. During Visit 2, subjects completed TTDPM and isometric knee strength testing prior to and following a fatiguing exercise protocol. Wilcoxon signed rank tests determined TTDPM and isometric knee strength changes from pre- to post- fatigue. Spearman’s rho correlation coefficients determined the relationship between strength and physiological variables with pre- to post-fatigue changes in TTDPM and with pre-fatigue and post-fatigue TTDPM in extension and flexion (α=0.05). No significant differences were demonstrated from pre-fatigue to post-fatigue TTDPM despite a significant decrease in isometric knee flexion strength (P<0.01) and flexion/extension ratio (P<0.05) following fatigue. No significant correlations were observed between strength or physiological variables and changes in TTDPM from pre- to post-fatigue in extension or flexion. Flexion/extension ratio was significantly correlated with pre-fatigue TTDPM in extension (r=-0.231, P<0.05). Peak oxygen uptake was significantly correlated with pre-fatigue (r=-0.500, P<0.01) and post-fatigue (r=-0.520, P<0.05) TTDPM in extension. No significant relationships were demonstrated between musculoskeletal and physiological characteristics and changes in TTDPM following fatigue. The results suggest that highly trained individuals may have better proprioception, and that the high fitness level of subjects in this investigation may have contributed to absence of TTDPM deficits following fatigue despite reaching a high level of perceptual and physiological fatigue. Future studies should consider various subject populations, other musculoskeletal strength characteristics, and different modalities of proprioception to determine the most important contributions to proprioceptive changes following fatigue

The Mediating Role of Vision in the Relationship Between Proprioception and Postural Control in Older Adults, as Compared to Teenagers and Younger and Middle-Aged Adults

[Abstract] The aim of this study is to analyze the mediating role of vision in the relationship between conscious lower limb proprioception (dominant knee) and bipedal postural control (with eyes open and closed) in older adults, as compared with teenagers, younger adults and middle-aged adults. Methods: The sample consisted of 119 healthy, physically active participants. Postural control was assessed using the bipedal Romberg test with participants’ eyes open and closed on a force platform. Proprioception was measured through the ability to reposition the knee at 45_, measured with the Goniometer Pro application’s goniometer. Results: The results showed an indirect relationship between proprioception and postural control with closed eyes in all age groups; however, vision did not mediate this relationship. Conclusions: Older adults outperformed only teenagers on the balance test. The group of older adults was the only one that did not display differences with regard to certain variables when the test was done with open or closed eyes. It seems that age does not influence performance on proprioception tests. These findings help us to optimize the design of training programs for older adults and suggest that physical exercise is a protective factor against age-related decline.This research recieved funding from Aristos Campus Mundus 2018 proyect. ID: ACM20180

The Relationship of Plantar Sensation with Standing Balance and Gait Post-Stroke

Gait and balance dysfunction after stroke limit independence and quality of life. Numerous contributing factors have been investigated but the role of sensation deficits has received little attention. This thesis investigated the relationship between plantar cutaneous sensation and 1) standing balance, 2) gait, and 3) use of vision to compensate for sensory loss with a secondary analysis of data from individuals with subacute stroke. Associations between standing balance, gait and sensation were investigated with Spearman correlations. Individuals classified as impaired or intact sensation were compared on gait and standing balance measures. This thesis found plantar sensation is related to standing balance but not spatiotemporal gait parameters. Individuals with impaired sensation were not more likely to employ vision as a compensatory strategy. These results suggest plantar sensation should be addressed during post-stroke rehabilitation of standing balance. Future work should investigate changes in cutaneous sensation with recovery of balance and gait post-stroke

Perception of Lower Extremity Loads in Stroke Survivors

Objective: This study aimed to improve our understanding of static and dynamic lower extremity sensory perception and the impact of sensory impairments on the control of walking in stroke survivors. Methods: Using a custom, real-time unloading system, we tested load perception at heel strike, mid stance and push off in 10 stroke survivors and compared their performance to 10 age-matched and 5 young adult control subjects. Dynamic load perception was based on a judgment of which leg was bearing more load, which was altered on a step by step basis. We also examined lower extremity static load perception, coordination, proprioception, balance, and gait symmetry. Results: The stroke survivors performed significantly worse than the control subjects in dynamic load perception, coordination, proprioception, balance and gait symmetry. Gait symmetry correlated with static and dynamic load perception measures but not with age, proprioception, coordination, and balance. Conclusions: Sensory deficits related to load detection in the impaired limb could result in an increased uncertainty of limb load and a gait strategy in which stroke survivors minimize loading of the impaired limb. Significance: This new method of measuring lower extremity dynamic load perception provides a framework for understanding gait-related sensory impairments in stroke survivors

Frontal plane hip and ankle sensorimotor function, not age, predicts unipedal stance time

Introduction: Changes occur in muscles and nerves with aging. In this study we explore the relationship between unipedal stance time (UST) and frontal plane hip and ankle sensorimotor function in subjects with diabetic neuropathy. Methods: UST, quantitative measures of frontal plane ankle proprioceptive thresholds, and ankle and hip motor function were tested in 41 subjects with a spectrum of lower limb sensorimotor function ranging from healthy to moderately severe diabetic neuropathy. Results: Frontal plane hip and ankle sensorimotor function demonstrated significant relationships with UST. Multivariate analysis identified only composite hip strength, ankle proprioceptive threshold, and age to be significant predictors of UST ( R 2 = 0.73), explaining 46%, 24%, and 3% of the variance, respectively. Conclusions: Frontal plane hip strength was the single best predictor of UST and appeared to compensate for less precise ankle proprioceptive thresholds. This finding is clinically relevant given the possibility of strengthening the hip, even in patients with significant peripheral neuropathy. Muscle Nerve, 2012Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90607/1/22325_ftp.pd

The impact of differential knee laxity on brain function/structure and postural control

Greater anterior knee laxity (AKL) is known to be a significant predictor of anterior cruciate ligament (ACL) injury. Individuals with high AKL are known to have a proprioception deficit and exhibit compensatory movement patterns. The potential altered sensory information and associated movement strategies may lead to decreased functional stability, contributing to a higher risk of ACL injury. The brain has an essential role in integrating and processing sensory information in the course of stabilizing the joint. Our brain also has the ability to reorganize its function and structure (neuroplasticity) in response to sensory changes. However, it is still unknown how sensory information, associated with ACL loading in high AKL individuals, may affect brain function and structure. Decreased proprioception influenced by high knee laxity may also negatively impact postural stability. Postural stability is impacted by visual, vestibular, somatosensory input. It is broadly understood that individuals who are ACL deficient as well as hypermobile individuals joints have poor proprioception and postural control. It is suggested that poor proprioception negatively impacts postural control. Decreased proprioception due to greater knee laxity may thus diminish postural stability. However, the influence of greater AKL on postural control is not yet understood. Therefore, the primary purpose of this study is to determine the impact of high and low knee laxity on brain function and structure as well as dynamic postural stability. Healthy and physically active female college students volunteered for this study. Anterior knee laxity was measured to assign participants to either high (N=15) or low knee laxity (N=12) groups. Functional and structural brain data were obtained through magnetic resonance imaging (MRI). Functional MRI data were analyzed in order to compare brain activation differences during anterior knee joint loading between the two groups. Structural brain data were analyzed to identify differences in gray matter volume between the groups. Time to stabilization testing following a single-leg jump landing task was recorded in order to quantify dynamic postural stability. Independent t-tests contrasted dynamic postural stability between high and low to average laxity groups. fMRI data revealed that those with high knee laxity had significantly less activation in the left superior parietal lobe and right premotor cortex, and greater activation in the right cerebellum (Crus I and II) during anterior knee joint loading. The results suggest that individuals with greater knee laxity might experience a different awareness of their body’s position and may face challenges in preplanning and preprogramming potential movements. We also observed that the high knee laxity group had a nearly significant larger gray matter volume in BA6 (premotor cortex and supplementary motor area). We suggest that the larger gray matter volume in BA6 may be a response to the challenges in preplanning movements as a compensatory strategy. However, the time to stabilization test did not reveal any differences between the high and low to average laxity group. An advanced postural control test that separated the influence of somatosensation from other sensory input (visual and vestibular) may be recommended in order to identify the differences in dynamic postural control between groups. Our study reveals valuable information concerning possible functional and structural neuroplasticity associated with knee laxity. These results may help researchers better understand the influence of knee laxity on the sensorimotor system, especially the central integration and processing components, in individuals who are at increased risk of ACL injury

Effect of drains on dynamic proprioception after arthroscopically assisted anterior cruciate ligament reconstruction

Background: Decrease in proprioception and kinesthesia occurs after ACL injury. Changes occurring within the joint following injury affect normal recruitment and firing patterns of the surrounding musculature. There are little data in the literature with reference to drain use after arthroscopic procedures on the knee or ACL reconstruction. The objective of the study was to determine the effect of postoperative drain use on proprioception after arthroscopically assisted anterior cruciate ligament (ACL) reconstruction with quadrupled hamstring graft.Methods: In this study, 54 arthroscopic ACL reconstruction patients were randomized for either intra-articular suction drain group or non-drain group. Outcome Assessment was done at 1 month, 3, 6 and 12 months after the surgery in which patients were assessed using Star excursion balance test by measuring excursion distances in each of the 8 directions.Results: Excursion distances in eight directions showed more increment in drainage tube (DT) group compared to no DT group. However it was found to be statistically significant only for posteromedial (p =0.018) and medial directions (p &lt;0.001).Conclusions: Postoperative drain should be used after arthroscopically assisted anterior cruciate ligament (ACL) reconstruction with quadrupled hamstring graft for improving the deficits in dynamic posture control

CLINICAL AND NEUROPHYSIOLOGICAL EFFECTS OF DRY NEEDLING ON INDIVIDUALS WITH CHRONIC ANKLE INSTABILITY

Ankle sprains are generally considered innocuous injuries; however, as many as 74% of patients will develop chronic symptoms. 1-3 Chronic ankle instability (CAI) is defined by a history of ankle sprain accompanied by ongoing bouts of giving way, residual ankle sprain symptoms, and a decrease in patient-perceived function. As understanding of sensorimotor deficits in individuals with CAI have advanced, treatment strategies have evolved to include a robust focus on balance training to mitigate dynamic and static postural control impairments exhibited in individuals with CAI. A problem arises as these improvements have not been conclusively linked to a decrease in CAI. Additionally, acknowledging the need for improved feed-forward postural control and the associated deficits in peripheral mechanoreceptors, treatments that directly affect peripheral receptors are lacking in current practices. Dry needling (DN) is a neurophysiological treatment tool that directly affects the neurophysiology of muscle, thereby likely affecting local muscle spindle receptors and feed forward postural control mechanisms. Currently, the effect of DN in the lower extremity on clinical and neurophysiologic components of balance is unknown. The long-term goal of this line of research is to improve health outcomes for individuals suffering a lateral ankle sprain. The first step toward this aim is understanding the neurophysiologic and sensorimotor effects of DN in both healthy individuals and those with CAI. Secondly, the appropriate dosage of DN treatment is currently unknown. Finally, identifying patient factors that may predict success with this treatment is clinically relevant and currently lacking. We hypothesized that 1) individuals with CAI would demonstrate larger immediate improvements in postural control compared to healthy controls 2) weekly, cumulative DN would demonstrate greater improvements in postural control and proprioception when compared to a single treatment and 3) baseline patient factors exist that predict individuals with CAI that will respond to DN treatment. The results of our first study illustrated that individuals with CAI indeed do have larger immediate improvements in postural control than healthy controls after a single DN treatment. While both groups demonstrated within group improvements in static and dynamic balance, individuals with CAI demonstrated greater improvements in dynamic balance measured with the Star Excursion Balance Test (SEBT). In our second study, weekly DN treatment produced immediate, but not greater improvements with cumulative treatments in dynamic postural control and inversion kinesthesia sense. However, cumulative treatments did produce improvements in eversion kinesthesia sense and static postural control in the mediolateral direction with eyes open, but with small to moderate effect sizes. In our final study, the Global Rating of Change (GROC) scale, a patient-oriented measure of overall improvement in symptoms, and the reach distance in the posteromedial direction of the SEBT as a clinician-oriented measure, were separately used to predict responders to DN treatment. Using the GROC, treatment expectation was found to be the single best predictor of treatment response. However, if the posteromedial direction of the SEBT was used to determine responders to DN treatment, both treatment expectation and a score ≥23.5 on the Identification of Functional Ankle Instability scale were found to be predictive of positive treatment response. In conclusion, DN individuals with CAI has demonstrated immediate improvement in dynamic postural control and proprioception, more than healthy controls. However, this improvement is not significantly augmented by subsequent treatments. Finally, baseline patient factors exist to predict responders to DN treatments. Factors predicting response to treatment differ based on patient or clinician-oriented determinants of treatment response to DN. These results are of an exploratory nature and thus should be interpreted with caution. Additional research is necessary to further elucidate aspects of this work, specifically response to various dosages to DN treatment, patient response when combining DN treatment with other rehabilitation treatments, baseline predictive factors and mechanistic explanations for improvements in postural control

The Relationships Among Proprioception, Balance, and Cognitive Perception of Body Awareness in College Students

Introduction: Proprioception is an important physiological function that is essential for activities of daily living as well as exercise and sport performance. Integration of proprioceptive signals plays a key role in both static and dynamic balance. Previously, researchers have assessed the relationship between balance and proprioception, however, the effect of cognitive perception of body awareness has not previously been included in this research. The aim of this pilot study was to explore the relationships among lower extremity proprioception, dynamic balance, and cognitive perception of body awareness in college students. Methods: Nineteen apparently healthy college students (age 21.26 ± 1.10 years, 12 female, 7 male) were recruited to voluntarily participate in this pilot study. An online survey of body awareness, Limits of Stability Test on the Biodex Balance System, and the Lower Extremity Position Test (LEPT) were used to measure cognitive perception of body awareness, balance, and proprioception, respectively. In order to establish test-retest reliability, 9 participants were randomly selected to repeat the test of proprioception one week following the initial data collection. Results: The LEPT yielded a questionable, but approaching acceptable, test-retest reliability (ɑ=.692). Balance and proprioception scores were moderately correlated (P=.031). Limb dominance had no significant impact on proprioception (P=.511). Previous dance and gymnastics experience had a medium effect size on balance performance (g=.502). Average LEPT error can reliably predict balance scores, accounting for 24.6% of the variance in scores (P=.026). Survey results were not related to balance (P=.188) or proprioception (P=.565) outcomes. Conclusion: The results of this pilot study found that balance is correlated with proprioception, proprioceptive ability is able to predict balance competence, limb dominance does not have a significant impact on proprioceptive ability, and participation in dance and gymnastics may result in improved balance. The LEPT still requires further improvements, but may be an acceptable clinical tool with financial feasibility, ease of administration, and time efficiency for quantifying proprioceptive ability compared to tools of higher precision. Future research should explore the impact of including an educational familiarization trial, control for LEPT starting joint position with an initial knee angle of 90° flexion, and a neutral ankle position (90° angle between the foot and leg) and consider the influence of muscle activation using electromyography. The role of cognitive perception of body awareness should be researched to a greater extent in order to determine its influence on balance and proprioception