Inter-limb mechanisms and clinical relevance of cross-education in humans

Al meer dan 100 jaar is bekend dat krachttraining met één arm of been zowel het getrainde als niet-getrainde ledemaat sterker maakt. Dit fenomeen wordt cross-education genoemd. De krachttoename van het niet-getrainde ledemaat bedraagt gemiddeld 52% van het getrainde ledemaat en kan worden verklaard door middel van twee theorieën. Het geheugenspoor van de getrainde beweging is of toegankelijk voor beide hersenhelften of bevindt zich in beide hersenhelften. De literatuurstudie laat zien dat het spiegelneuronen systeem, dat visuele informatie van de beweging via sensorische neuronen verbindt met de motoneuronen die de beweging uitvoeren, ook een rol speelt in cross-education. Observatie van eenzijdige bewegingen in een spiegel zou daarom de transfer naar de niet-getrainde zijde moeten vergroten ten opzichte van training zonder een spiegel. Als verondersteld, spiegeltraining leidt acuut tot een afname in intracorticale prikkelbaarheid van de primaire motorische cortex en chronisch tot een toename van het cross-education effect en een afname in intracorticale inhibitie. Onderzoek naar de klinische relevantie van deze neurofysiologische bevindingen laat zien dat patiënten na een voorste kruisband (VKB) ruptuur neuromusculaire gebreken vertonen in zowel het geblesseerde als niet-geblesseerde been. Een randomized clinical trial werd uitgevoerd om te zien of quadriceps zwakte in het geopereerde been na een VKB reconstructie kan worden verminderd door extra krachttraining te doen met het niet-geblesseerde been. De cross-education training leidde niet tot sneller herstel na de VKB operatie ten opzichte van de reguliere revalidatie. Cross-education zou wel zinvol kunnen zijn voor patiënten die de aangedane zijde niet kunnen trainen vanwege immobilisatie

Levels of self-reported and objective physical activity in individuals with age-related macular degeneration

Background: Self-report in people with age-related macular degeneration (AMD) shows that they lead less active lifestyles. Physical activity is important as it has been shown to improve quality of life, reduce co-morbidity and also slow down the progression of AMD. Self-reported measures of physical activity are prone to subjective biases and therefore less accurate in quantifying physical activity. This study compared self-reported and objective (accelerometer-based) physical activity levels and patterns in older adults with AMD. Methods: Data were collected in 11 AMD subjects with binocular vision loss (aged 76 ± 7 years), 10 AMD subjects with good binocular vision (aged 76 ± 7 years), and 11 controls (aged 70 ± 4 years). Binocular vision was established using visual acuity score. Contrast sensitivity and visual fields were also measured. Self-reported sedentary behaviour and moderate-to-vigorous physical activity (MVPA) was assessed using the Global Physical Activity Questionnaire. Objective measurements were obtained with an Actigraph GT3X accelerometer being worn for seven consecutive days on the hip. The objective physical activity measures were sedentary behaviour, light physical activity, MVPA, and step count. Results: Objectively measured MVPA was 33–34% higher for controls compared to both AMD groups (p  0.05). Comparing the objective with the self-report physical activity measure showed that all groups under-reported their sedentary behaviour and MVPA, but controls under-reported their MVPA more than both AMD groups (p < 0.05). Weak to moderate correlations were observed between the severity of vision loss and objective physical activity measures (all − 0.413 ≥ r ≤ 0.443), while correlations for self-reported physical activity measures were less strong (all − 0.303 ≥ r ≤ 0.114). Conclusions: People with AMD, irrespective of whether they were vision impaired, were better able to estimate the time spent in MVPA compared to controls. However, objectively measured MVPA, was higher in controls than AMD subjects. Although clinicians may use self-report to monitor the compliance of AMD subjects with any prescribed exercise programs, they should be aware that a valid comparison with healthy controls can only be made when MVPA is objectively measured

The effects of temporal pressure on obstacle negotiation and gaze behaviour in young adults with simulated vision loss

Individuals with vision loss adapt their locomotion and gaze behaviour to safely negotiate objects in temporally unconstrained situations. However, everyday activities are often performed under time-pressure. We investigated the effects of blur on anxiety, movement kinematics and gaze behaviour during the negotiation of a floor-based obstacle under three amounts of pressure: 1) no-pressure; 2) tonal-pressure: an intermittent tone was played at a constant frequency; 3) tonal + time pressure: the intermittent tone increased in frequency and participants had to walk 20% faster to reach the end of the lab. Irrespective of the amount of pressure, the blurred vs. normal vision group reported 32% more anxiety, lifted the lead foot 43% higher and 10% slower over the obstacle, and looked 6% longer and 6% more frequently ahead of the obstacle. In the tonal + time pressure vs. no-pressure condition, both groups were more anxious, showed adaptations in movement kinematics related to walking faster, and adopted a ‘checking strategy’ by shortening their fixation durations at the obstacle. These results show that irrespective of temporal pressure, the blurred vision group remained more cautious as to how the lead foot negotiated the obstacle, in order to reduce the chance of tripping during crossing

An anterior cruciate ligament injury does not affect the neuromuscular function of the non-injured leg except for dynamic balance and voluntary quadriceps activation

The function of the anterior cruciate ligament (ACL) patients' non-injured leg is relevant in light of the high incidence of secondary ACL injuries on the contralateral side. However, the non-injured leg's function has only been examined for a selected number of neuromuscular outcomes and often without appropriate control groups. We measured a broad array of neuromuscular functions between legs of ACL patients and compared outcomes to age, sex, and physical activity matched controls. Thirty-two ACL-deficient patients (208 +/- 145 days post-injury) and active and less-active controls (N = 20 each) participated in the study. We measured single- and multi-joint neuromuscular function in both legs in each group and expressed the overall neuromuscular function in each leg by calculating a mean z-score across all neuromuscular measures. A group by leg MANOVA and ANOVA were performed to examine group and leg differences for the selected outcomes. After an ACL injury, duration (-4.3 h/week) and level (Tegner activity score of -3.9) of sports activity decreased and was comparable to less-active controls. ACL patients showed bilateral impairments in the star excursion balance test compared to both control groups (P Except for poorer dynamic balance and reduced quadriceps activation, ACL patients had no bilateral neuromuscular deficits despite reductions in physical activity after injury. Therapists can use the non-injured leg as a reference to assess the injured leg's function for tasks measured in the present study, excluding dynamic balance and quadriceps activation. Rehabilitation after an ACL injury should be mainly focused on the injured leg. III

Cross-education does not accelerate the rehabilitation of neuromuscular functions after ACL reconstruction: a randomized controlled clinical trial

Purpose: Cross-education reduces quadriceps weakness 8 weeks after anterior cruciate ligament (ACL) surgery, but the long-term effects are unknown. We investigated whether cross-education, as an adjuvant to the standard rehabilitation, would accelerate recovery of quadriceps strength and neuromuscular function up to 26 weeks post-surgery. Methods: Group allocation was randomized. The experimental (n = 22) and control (n = 21) group received standard rehabilitation. In addition, the experimental group strength trained the quadriceps of the non-injured leg in weeks 1–12 post-surgery (i.e., cross-education). Primary and secondary outcomes were measured in both legs 29 ± 23 days prior to surgery and at 5, 12, and 26 weeks post-surgery. Results: The primary outcome showed time and cross-education effects. Maximal quadriceps strength in the reconstructed leg decreased 35% and 12% at, respectively, 5 and 12 weeks post-surgery and improved 11% at 26 weeks post-surgery, where strength of the non-injured leg showed a gradual increase post-surgery up to 14% (all p ≤ 0.015). Limb symmetry deteriorated 9–10% more for the experimental than control group at 5 and 12 weeks post-surgery (both p ≤ 0.030). One of 34 secondary outcomes revealed a cross-education effect: Voluntary quadriceps activation of the reconstructed leg was 6% reduced for the experimental vs. control group at 12 weeks post-surgery (p = 0.023). Both legs improved force control (22–34%) and dynamic balance (6–7%) at 26 weeks post-surgery (all p ≤ 0.043). Knee joint proprioception and static balance remained unchanged. Conclusion: Standard rehabilitation improved maximal quadriceps strength, force control, and dynamic balance in both legs relative to pre-surgery but adding cross-education did not accelerate recovery following ACL reconstruction

Apport de l'aromathérapie dans la prise en charge des pathologies respiratoires basses (exemple de la broncho-pneumopathie chronique obstructive)

STRASBOURG ILLKIRCH-Pharmacie (672182101) / SudocSudocFranceF

Role of the mirror-neuron system in cross-education

The present review proposes the untested hypothesis that cross-education performed with a mirror increases the transfer of motor function to the resting limb compared with standard cross-education interventions without a mirror. The hypothesis is based on neuroanatomical evidence suggesting an overlap in activated brain areas when a unilateral motor task is performed with and without a mirror in the context of cross-education of the upper extremities. The review shows that the mirror-neuron system (MNS), connecting sensory neurons responding to visual properties of an observed action and motor neurons that discharge action potentials during the execution of a similar action, has the potential to enhance cross-education. After a literature search we narrowed the review to studies that examined healthy young adults who performed unilateral strength training and unilateral motor tasks with or without a mirror and assessed outcome measures in relation to the changes in brain activity, motor cortical excitability, and corticospinal excitability. We identified six chronic studies that examined the effects of unilateral strength training on neural adaptations and 15 cross-sectional studies that examined acute changes in brain activation, motor cortical and corticospinal excitability using imaging, electroencephalographic, magnetoencephalographic, and magnetic brain stimulation. There were two chronic and nine cross-sectional studies in which participants performed unilateral motor tasks while viewing the image of the active hand superimposed on the resting hand’s image. Collectively, the data suggest that the MNS is involved in cross-education and the hypothesis is tenable. However, future studies are needed to elucidate the precise mechanism of how the use of a mirror in a cross-education study augments transfer to the non-exercised limb. Recent studies show a strength-sparing effect in the immobilized arm after strength training of the free arm in healthy individuals, and improved bilateral function after unilateral exercise therapy in stroke patients. It is thus conceptually justified to conduct randomized clinical trials that supplement cross-education protocols with a mirror. Such a treatment could reduce muscle weakness caused by limb fractures, anterior-cruciate ligament reconstruction surgery, stroke, and other unilateral motor dysfunctions