The association between muscle strength and activity limitations in patients with the hypermobility type of Ehlers–Danlos syndrome : the impact of proprioception

Purpose: The patients diagnosed with Ehlers-Danlos Syndrome Hypermobility Type (EDS-HT) are characterized by pain, proprioceptive inacuity, muscle weakness, potentially leading to activity limitations. In EDS-HT, a direct relationship between muscle strength, proprioception and activity limitations has never been studied. The objective of the study was to establish the association between muscle strength and activity limitations and the impact of proprioception on this association in EDS-HT patients. Methods: Twenty-four EDS-HT patients were compared with 24 controls. Activity limitations were quantified by Health Assessment Questionnaire (HAQ), Six-Minute Walk test (6MWT) and 30-s chair-rise test (30CRT). Muscle strength was quantified by handheld dynamometry. Proprioception was quantified by movement detection paradigm. In analyses, the association between muscle strength and activity limitations was controlled for proprioception and confounders. Results: Muscle strength was associated with 30CRT (r = 0.67, p = <0.001), 6MWT (r = 0.58, p = <0.001) and HAQ (r = 0.63, p = <0.001). Proprioception was associated with 30CRT (r = 0.55, p <0.001), 6MWT (r = 0.40, p = <0.05) and HAQ (r = 0.46, p < 0.05). Muscle strength was found to be associated with activity limitations, however, proprioceptive inacuity confounded this association. Conclusions: Muscle strength is associated with activity limitations in EDS-HT patients. Joint proprioception is of influence on this association and should be considered in the development of new treatment strategies for patients with EDS-HT. Implications for rehabilitation : Reducing activity limitations by enhancing muscle strength is frequently applied in the treatment of EDS-HT patients. Although evidence regarding treatment efficacy is scarce, the current paper confirms the rationality that muscle strength is an important factor in the occurrence of activity limitations in EDS-HT patients. Although muscle strength is the most dominant factor that is associated with activity limitations, this association is confounded by proprioception. In contrast to common belief proprioception was not directly associated with activity limitations but confounded this association. Controlling muscle strength on the bases of proprioceptive input may be more important for reducing activity limitations than just enhancing sheer muscle strength

Space adaptation syndrome experiments (8-IML-1)

A set of seven experiments will study adaptation of the human nervous system to weightlessness. Particular emphasis will be placed on the vestibular and proprioceptive systems. The experiments are as follows: the sled/H-reflex; rotation/vestibulo-ocular reflex; the visual stimulator experiment; proprioception (relaxed) experiment; proprioception (active) experiment; proprioception (illusion) experiment; and tactile acuity

Comparison of Ankle Proprioception Between Pregnant and Non Pregnant Women

Pregnant women report falls especially during their third trimester. Physiological changes along with ligament laxity can affect the joint proprioception in this population. This study was conducted to compare the ankle proprioception between pregnant and non pregnant women. Thirty pregnant and 30 non pregnant women were included in the study and the position of ankles were recorded by a digital camera placed 60 cms away from the feet of the subject. UTHSCSA Image tool software version 3.0. was used to measure the difference between the initial and the final angle. The median repositioning error in the pregnant group was 11.6 (7.6, 12.4) degrees and the median repositioning error in the non-pregnant group was 4.2 (2.1, 6.3) degrees. There was a statistically significant difference in ankle joint proprioception between pregnant and non pregnant women

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

EEG and EMG Sensorimotor Measurements to Assess Proprioception Following ACL Reconstruction

The Anterior Cruciate Ligament (ACL) is the primary source of rotational stability in the knee by preventing the tibia from sliding in front of the femur. When the ACL is torn, it typically must be repaired through reconstructive surgery which results in proprioceptive deficiencies in the knee. Proprioception plays an important role in understanding where one’s knee is in space, sensing movement and reacting accordingly. This study examines an alternative method of measuring proprioceptive responses to a stimulus (motion) by using electromyogram (EMG) and electroencephalogram (EEG) signals to observe muscle and brain activity. Two participants (one with an ACL reconstruction and a second with healthy knees) were tested three times over a six week period. Repeated measures allowed for an initial examination of how proprioception may vary over time in an individual with healthy knees and with an ACL reconstruction. This measurement strategy can examine the process of proprioception recovery after an ACL reconstruction. It has the potential to help physicians and physical therapists decide when a person can return to normal or strenuous activity as well as provide insight into whether uninjured patients have a proprioceptive deficit which may indicate an increased risk of injury

The effects of Tai Chi on peripheral somatosensation, balance, and fitness in Hispanic older adults with type 2 diabetes:a pilot and feasibility study

Peripheral neuropathy and loss of somatosensation in older adults with type 2 diabetes can increase risk of falls and disability. In nondiabetic older adult population Tai Chi has been shown to enhance balance and fitness through improvements in somatosensation and neuromuscular control, and it is unclear if Tai Chi would elicit similar benefits in older adults with diabetes. Therefore, the purpose of this study was to investigate the effects of an 8-week, three-hour-per-week Tai Chi intervention on peripheral somatosensation in older adults with type 2 diabetes. Participants were eight Hispanic older adults with type 2 diabetes who participated in the Tai Chi intervention and a convenience sample of Hispanic older adults as a referent group. Baseline and postintervention assessments included ankle proprioception, foot tactile sense, plantar pressure distribution, balance, and fitness. After intervention, older adults with type 2 diabetes showed significant improvements in ankle proprioception and fitness and decreased plantar pressure in the forefoot, with no statistical effect noted in balance or tactile sensation. Study results suggest that Tai Chi may be beneficial for older adults with diabetes as it improves ankle proprioception; however, study findings need to be confirmed in a larger sample size randomized controlled trial

Manual Matching Of Perceived Surface Orientation Is Affected By Arm Posture: Evidence Of Calibration Between Proprioception And Visual Experience In Near Space

Proprioception of hand orientation (orientation production using the hand) is compared with manual matching of visual orientation (visual surface matching using the hand) in two experiments. In experiment 1, using self-selected arm postures, the proportions of wrist and elbow flexion spontaneously used to orient the pitch of the hand (20 and 80%, respectively) are relatively similar across both manual matching tasks and manual orientation production tasks for most participants. Proprioceptive error closely matched perceptual biases previously reported for visual orientation perception, suggesting calibration of proprioception to visual biases. A minority of participants, who attempted to use primarily wrist flexion while holding the forearm horizontal, performed poorly at the manual matching task, consistent with proprioceptive error caused by biomechanical constraints of their self-selected posture. In experiment 2, postural choices were constrained to primarily wrist or elbow flexion without imposing biomechanical constraints (using a raised forearm). Identical relative offsets were found between the two constraint groups in manual matching and manual orientation production. The results support two claims: (1) manual orientation matching to visual surfaces is based on manual proprioception and (2) calibration between visual and proprioceptive experiences guarantees relatively accurate manual matching for surfaces within reach, despite systematic visual biases in perceived surface orientation

Exploiting Multiple Sensory Modalities in Brain-Machine Interfaces

Recent improvements in cortically-controlled brain-machine interfaces (BMIs) have raised hopes that such technologies may improve the quality of life of severely motor-disabled patients. However, current generation BMIs do not perform up to their potential due to the neglect of the full range of sensory feedback in their strategies for training and control. Here we confirm that neurons in the primary motor cortex (MI) encode sensory information and demonstrate a significant heterogeneity in their responses with respect to the type of sensory modality available to the subject about a reaching task. We further show using mutual information and directional tuning analyses that the presence of multi-sensory feedback (i.e. vision and proprioception) during replay of movements evokes neural responses in MI that are almost indistinguishable from those responses measured during overt movement. Finally, we suggest how these playback-evoked responses may be used to improve BMI performance

Evolution and Mirror Neurons. An Introduction to the Nature of Self-Consciousness

Self-consciousness is a product of evolution. Few people today disagree with the evolutionary history of humans. But the nature of self-consciousness is still to be explained, and the story of evolution has rarely been used as a framework for studies on consciousness during the 20th century. This last point may be due to the fact that modern study of consciousness came up at a time where dominant philosophical movements were not in favor of evolutionist theories (Cunningham 1996). Research on consciousness based on Phenomenology or on Analytic Philosophy has been mostly taking the characteristics of humans as starting points. Relatively little has been done with bottom-up approaches, using performances of animals as a simpler starting point to understand the generation of consciousness through evolution. But this status may be changing, thanks to new tools coming from recent discoveries in neurology. The discovery of mirror neurons about ten years ago (Gallese et al. 1996, Rizzolatti et al. 1996) has allowed the built up of new conceptual tools for the understanding of intersubjectivity within humans and non human primates (Gallese 2001, Hurley 2005). Studies in these fields are still in progress, with discussions on the level of applicability of this natural intersubjectivity to non human primates (Decety and Chaminade 2003). We think that these subject/conspecific mental relations made possible by mirror neurons can open new paths for the understanding of the nature of self-consciousness via an evolutionist bottom-up approach. We propose here a scenario for the build up of self-consciousness through evolution by a specific analysis of two steps of evolution: first step from simple living elements to non human primates comparable to chimpanzees, and second step from these non human primates to humans. We identify these two steps as representing the evolution from basic animal awareness to body self-awareness, and from body self-awareness to self-consciousness. (we consider that today non human primates are comparable to what were pre-human primates). We position body self-awareness as corresponding to the performance of mirror self recognition as identified with chimpanzees and orangutans (Gallup). We propose to detail and understand the content of this body self-awareness through a specific evolutionist build up process using the performances of mirror neurons and group life. We address the evolutionary step from body self-awareness to self-consciousness by complementing the recently proposed approach where self-consciousness is presented as a by-product of body self-awareness amplification via a positive feedback loop resulting of anxiety limitation (Menant 2004). The scenario introduced here for the build up of self-consciousness through evolution leaves open the question about the nature of phenomenal-consciousness (Block 2002). We plan to address this question later on with the help of the scenario made available here