Mid Sweden University

Ventrolateral prefrontal cortex (VLPFC) is part of a network that exerts inhibitory control over the motor cortex (MC). Recently, we demonstrated that VLPFC was more activated during imagined maximum eccentric than during imagined concentric contractions in healthy participants. This was accompanied with lower activation levels within motor regions during imagined eccentric contractions. The aim was to test a novel hypothesis of an involvement of VLPFC in contraction mode-specific modulation of force. Functional magnetic resonance imaging was used to examine differences in VLPFC and motor regions during the concentric and the eccentric phases of imagined maximum contractions in a selected sample of subjects with stroke (n=4). The subjects were included as they exhibited disturbed modulation of force. The previously demonstrated pattern within VLPFC was evident only on the contralesional hemisphere. On the ipsilesional hemisphere, the recruitment in VLPFC was similar for both modes of contractions. The findings support a hypothesis of the involvement of VLPFC in contraction mode-specific modulation of maximum force production. A disturbance of this system might underlie the lack of contraction mode-specific modulation commonly found among stroke subjects, often expressed as an increased ratio between eccentric and concentric strength.

Background: Resistance exercise comprising eccentric (ECC) muscle actions enhances muscle strength and function to aid stroke patients in conducting daily tasks. The purpose of this study was to assess the efficacy of a novel ECC-overload flywheel resistance exercise paradigm to induce muscle and functional performance adaptations in chronic stroke patients. Methods: Twelve patients (similar to 8 years after stroke onset) performed 4 sets of 7 coupled concentric (CON) and ECC actions using the affected limb on a flywheel leg press (LP) device twice weekly for 8 weeks. Maximal CON and ECC isokinetic torque at 30, 60 and 90 degrees/s, isometric knee extension and LP force, and CON and ECC peak power in LP were measured before and after training. Balance (Berg Balance Scale, BBS), gait (6-Min Walk test, 6MWT; Timed-Up-and-Go, TUG), functional performance (30-s Chair-Stand Test, 30CST), spasticity (Modified Ashworth Scale) and perceived participation (Stroke Impact Scale, SIS) were also determined. Results: CON and ECC peak power increased in both the trained affected (34 and 44%; P < 0.01), and the untrained, non-affected leg (25 and 34%; P < 0.02). Power gains were greater (P = 0.008) for ECC than CON actions. ECC isokinetic torque at 60 and 90 degrees/s increased in the affected leg (P < 0.04). The increase in isometric LP force for the trained, affected leg across tests ranged 10-20% (P < 0.05). BBS (P = 0.004), TUG (P = 0.018), 30CST (P = 0.024) and SIS (P = 0.058) scores improved after training. 6MWT and spasticity remained unchanged. Conclusions: This novel, short-term ECC-overload flywheel RE training regime emerges as a valid, safe and viable method to improve muscle function, balance, gait and functional performance in men and women suffering from chronic stroke.

Background: Chronic whiplash-associated disorders (WADs) are often associated with social functioning problems and decreased ability to perform previous activities. This may lead to decreased life satisfaction, which is insufficiently studied in the context of whiplash injuries. Symptoms included in chronic WAD are similar to symptoms frequently reported by persons who have sustained mild traumatic brain injury (MTBI)/concussion. In cases of MTBI, the severity and number of symptoms have been suggested to have a diagnostic value. The corresponding importance of symptoms in chronic WAD has not been documented. Most studies of whiplash injuries have focused on neck pain because this is the dominant complaint, while other symptoms are less studied. The frequency of long-term symptoms after whiplash injuries seems to vary. It is difficult to compare the long-term outcome since the follow-up after whiplash injury in most studies has been rather short. Therefore, the primary aim of this investigation was to study neck pain and other symptoms, disability, and life satisfaction five years after whiplash injury in a defined population and geographical area. Methods: The study was carried out at a public hospital in northern Sweden and was a cross-sectional survey of patients five years after the injury event in a cohort of whiplash-injured patients. Five years after the emergency department visit, 186 persons aged 18-64 answered questionnaires on symptoms (Rivermead Post-Concussion Symptoms Questionnaire, RPQ), disabilities (Rivermead Head Injury Follow Up Questionnaire, RHFUQ), and life satisfaction (LiSat-11). The answers were compared to those of a comparison cohort. Results: The most common symptoms five years after whiplash injury were fatigue (41%), poor memory (39%), and headache (37%). Inability to sustain previous workload (44%) and fatigue at work (43%) were frequently reported disabilities. Only 39% were satisfied with their somatic health and 60% with their psychological health. Compared with healthy controls, the whiplash injured exhibited more symptoms and had lower life satisfaction. Women reported significantly higher pain intensity than men. Few significant differences between women and men regarding the other parameters were found. Conclusions: This study shows that five years after a whiplash injury, patients reported symptoms that are typical of mild traumatic brain injury. Further, this study emphasizes the possibility of screening patients with chronic WAD for these symptoms as a complement to the assessment. Implications: Untreated symptoms may negatively affect the outcome of pain rehabilitation. This implies that it might be clinically meaningful to quantify symptoms earlier in the rehabilitation process.

Objective: To investigate sex differences in symptoms, structure of symptoms, disability and life satisfaction 3 years after mild traumatic brain injury. Secondary aims were to find risk factors for adverse outcome. Design: Population-based cohort study. Patients: The cohort comprised 137,000 inhabitants at risk in a defined population served by a single hospital in northern Sweden. Patients attending the emergency department following a mild traumatic brain injury in 2001 were included. Methods: Of 214 patients aged 18-64 years, 163 answered a questionnaire on symptoms, disability, and life-satisfaction 3 years post-injury. The instruments were analysed with descriptive statistics. A principal component analysis of the Rivermead Post-Concussion Symptoms Questionnaire was conducted. Risk factors were identified using logistic regression. Results: Post-concussion syndrome was found in 50% of the women and 30% of the men. Disability was found in 52% of the women and 37% of the men, and 57% of the women and 56% of the men were satisfied with their lives. For both genders, high frequency of symptoms was a risk factor for disability and low life satisfaction. Back pain was a risk factor for disability. Living alone was a risk factor for low levels of life satisfaction. The principal component analysis revealed differences between the sexes. Conclusion: There are sex differences in outcome 3 years after mild traumatic brain injury. Women and men should be analysed separately.

Objective: To examine the annual incidence of acute whiplash injuries after road traffic crashes in a geographic catchment area in Northern Sweden during the period 2000-2009. Design: Descriptive epidemiology determined by prospectively collected data from a defined population. Setting: The study was conducted at a public hospital in Sweden. Participants: The population of the hospital's catchment area (136,600 inhabitants in 1999 and 144,500 in 2009). Methods: At the emergency department, all injured persons (approximately 11,000 per year) were asked to answer a questionnaire about the injury incident. Data from the medical records also were analyzed. From 2000-2009, 15,506 persons were injured in vehicle crashes. Persons who were subject to an acute neck injury within whiplash-associated disorder grades 1-3 were included. The overall and annual incidences were calculated as incidence. Age, gender, type of injury event, and direction of impact were described. The incidences were compared with national statistics on insurance claims from 2003, 2007, and 2008 to detect changes in the proportions of claims. Main Outcome Measures: The annual incidence of acute whiplash injuries. Secondary outcome measures were types of injury events, age and gender distribution, changes in the proportion of rear-end crashes during 2000-2009, and changes in the proportion of insurance claims during 2003-2008. Results: During 2000-2009, 3297 cases of acute whiplash injury were encountered. The overall incidence was 235/100,000/year. The average yearly increase in incidence was 1.0%. Women comprised 51.9% and men 48.1% of the injured. Car occupants (86.4%) and bicycle riders (6.1%) were most frequently injured. The proportion of rear-end crashes decreased from 55% to 45% from 2000-2009. The proportion of insurance claims significantly decreased between 2003 and 2008 (P &lt; .0001, χ 2 test). Conclusion: The incidence of emergency department visits attributable to acute whiplash injuries after road traffic crashes have been relatively stable during the past decade in our area, except in 2007 and 2008, when a peak occurred. © 2012 American Academy of Physical Medicine and Rehabilitation.

In this study we used functional magnetic resonance imaging (fMRI) to examine differences in recruited brain regions during the concentric and the eccentric phase of an imagined maximum resistance training task of the elbow flexors in healthy young subjects. The results showed that during the eccentric phase, pre-frontal cortex (BA44) bilaterally was recruited when contrasted to the concentric phase. During the concentric phase, however, the motor and pre-motor cortex (BA 4/6) was recruited when contrasted to the eccentric phase. Interestingly, the brain activity of this region was reduced, when compared to the mean activity of the session, during the eccentric phase. Thus, the neural mechanisms governing imagined concentric and eccentric contractions appear to differ. We propose that the recruitment of the pre-frontal cortex is due to an increased demand of regulating force during the eccentric phase. Moreover, it is possible that the inability to fully activate a muscle during eccentric contractions may partly be explained by a reduction of activity in the motor and pre-motor cortex.

Our objective was to assess the loading during a resistance-training task at a given training intensity in subjects with stroke and in healthy subjects. Subjects with stroke (n = 11) and two control groups (n = 11 in each) underwent strength measurements and a resistance-training task for elbow flexors. Torque and muscular activity obtained during the resistance-training task was related to values obtained during strength measurements. Even if relative loading throughout the concentric phase of the resistance-training task, expressed as percent of concentric isokinetic torque, was found to be similar among groups, we found indications of insufficient loading for the stroke group. Relative loading during the eccentric contraction phase, expressed as percent of eccentric isokinetic torque, was significantly lower for the stroke group. Also, when related to isometric maximum voluntary contraction, the loading was significantly lower for the stroke group, compared with the control groups, during the concentric and eccentric contraction phases. Furthermore, muscle activation during, as well as muscular fatigue after, the resistance-training task was somewhat lower for the stroke group. Hence, for subjects with stroke, the relative loading during resistance training, performed at a training intensity considered adequate for able-bodied, appears to be too low compared with the healthy controls. © 2012 Informa Healthcare.

The aim of this study was to compare the effect of isokinetic contraction mode and velocity on the torque-angle relationship during maximum voluntary elbow flexion in patients with stroke, age-matched healthy subjects and young subjects. To eliminate the effect of torque amplitude differences between subjects and groups, the torque values throughout the ROM were individually normalized to the peak value for each contraction velocity. The results indicate that in stroke patients the normalized torque angle relationship during the eccentric contractions was better preserved than during concentric contractions. Specifically, during eccentric contractions, stroke patients exhibited a torque-angle relationship that was closer to normal as the test velocity increased. The opposite trend could be seen in concentric contractions where the torque-angle relationship became more divergent from normal with a rise in the velocity. The torque-angle relationships were essentially the same for the control groups, irrespective of contraction mode or velocity. These findings may have significance for loading patterns of resistance training exercises used with stroke patients as such exercises normally are biomechanically designed for normal torque angle relationships. In clinical practice, these findings may partly explain why the strength increases due to resistance training are limited for patients with stroke.