Helen Dawes

Cognitive motor interference while walking: A systematic review and meta-analysis

Dual-task methodology has been increasingly used to assess cognitive motor interference while walking. However, whether the observed dual-task-related gait changes are systematically related to methodological variations remains unclear and researchers still lack knowledge of what cognitive task to use in different groups for clinical purposes or for research. We systematically reviewed experimental studies that measured gait performance with and without performing concurrent cognitive task. Our results suggest that cognitive tasks that involve internal interfering factors seem to disturb gait performance more than those involving external interfering factors. Meta-analysis results show that the overall effect of different cognitive tasks was prominent in gait speed. In healthy participants, meta-regression analysis suggests strong associations between age and speed reduction under dual-task conditions and between the level of cognitive state and speed reduction under dual-task conditions. Standardizing research methodologies, as well as improving their ecological validity, enables better understanding of dual-task-related gait changes in different populations and improves, in turn, our understanding of neural mechanisms and gait control in general in content.

Treadmill training for individuals with multiple sclerosis: a pilot randomised trial

This pilot study investigated whether 4 weeks of aerobic treadmill training in individuals with multiple sclerosis (MS) improved mobility and reduced fatigue. Individuals with MS were recruited to this prospective, randomised controlled trial. Individuals were assessed at baseline, week 7 and 12 with a 10 metre timed walk, a 2 minute walk, the Rivermead Mobility Index, and the Fatigue Severity Scale. After a pre-assessment familiarisation session and a baseline assessment, individuals were randomly allocated to an initial intervention or delayed intervention group. Treadmill training consisted of 4 weeks of supervised aerobic exercise delivered weeks 3–6 in the immediate group and 8–11 in the delayed group. Of the initial 19 recruits, 16 individuals completed the study. There was a significant difference in walking endurance between the delayed and immediate groups at baseline (p<0.05). On reassessment in week 7, decreases in 10 metre walk time were found in both groups, which was significant in the immediate group (p<0.05). The 2 minute walk distance significantly increased in both groups (p<0.05). In the training group, reassessed at week 12 after training ceased, there was a return towards baseline scores. No significant changes in fatigue scores were found. This study showed that in individuals with MS, aerobic treadmill training is feasible and well tolerated. Walking speed and endurance increased following training with no increase in reported fatigue. Detraining occurred in the period following training. A larger randomised clinical trial is warranted.

Brain Activity Changes Associated With Treadmill Training After Stroke

Background and Purpose— The mechanisms underlying motor recovery after stroke are not fully understood. Several studies used functional MRI longitudinally to relate brain activity changes with performance gains of the upper limb after therapy, but research into training-induced recovery of lower limb function has been relatively neglected thus far. Methods— We investigated functional reorganization after 4 weeks of treadmill training with partial body weight support in 18 chronic patients (mean age, 59.9±13.5 years) with mild to moderate paresis (Motricity Index affected leg: 77.7±10.5; range, 9 to 99) and gait impairment (Functional Ambulation Category: 4.4±0.6; range, 3 to 5) due to a single subcortical ischemic stroke using repeated 3.0-T functional MRI and an ankle-dorsiflexion paradigm. Results— Walking endurance improved after training (2-minute timed walking distance: 121.5±39.0 versus pre: 105.1±38.1 m; P=0.0001). For active movement of the paretic foot versus rest, greater walking endurance correlated with increased brain activity in the bilateral primary sensorimotor cortices, the cingulate motor areas, and the caudate nuclei bilaterally and in the thalamus of the affected hemisphere. Conclusions— Despite the strong subcortical contributions to gait control, rehabilitation-associated walking improvements are associated with cortical activation changes. This is similar to findings in upper limb rehabilitation with some differences in the involved cortical areas. We observed bihemispheric activation increases with greater recovery both in cortical and subcortical regions with movement of the paretic foot. However, although the dorsal premotor cortex appears to play an important role in recovery of hand movements, evidence for the involvement of this region in lower extremity recovery was not found.

Can aerobic treadmill training reduce the effort of walking and fatigue in people with multiple sclerosis: a pilot study

Impaired mobility in multiple sclerosis (MS) is associated with high-energy costs and effort when walking, gait abnormalities, poor endurance and fatigue. This repeated measures trial with blinded assessments investigated the effect of treadmill walking at an aerobic training intensity in 16 adults with MS. The intervention consisted of 12 sessions of up to 30 minutes treadmill training (TT), at 55–85% of age-predicted maximum heart rate. The primary outcome measure was walking effort, measured by oxygen consumption (mL/kg per metre), during treadmill walking at comfortable walking speed (CWS). Associated changes in gait parameters using the ‘Gait-Rite’ mat, 10-m time and 2-minute distance, and Fatigue Severity Scale were examined. Following training, oxygen consumption decreased at rest (P = 0.008), CWS increased (P = 0.002), and 10-m times (P = 0.032) and walking endurance (P = 0.020) increased. At increased CWS, oxygen consumption decreased (P = 0.020), with a decreased time spent in stance in the weaker leg (P = 0.034), and a greater stride distance with the stronger leg (P = 0.044). Reported fatigue levels remained the same. Aerobic TT presents the opportunity to alter a motor skill and reduce the effort of walking, whilst addressing cardiovascular de-conditioning, thereby, potentially reducing effort and fatigue for some people with MS.

The Effects of Stretching in Spasticity: A Systematic Review

OBJECTIVES To investigate the general effect of stretching on spasticity and to explore the complexity of stretching in patients with spasticity. DATA SOURCES Two researchers independently performed a systematic literature search using the databases: Medline, PEDro, Cochrane library, Web of Science, CINAHL, and Allied and Complementary Medicine. STUDY SELECTION Studies on adults receiving a stretching technique to reduce spasticity were included. DATA EXTRACTION Randomized controlled trials (RCTs) were assessed on the PEDro scale for methodologic quality. Thirteen items from the CONSORT list and the Critical Appraisal Skills Program guideline were used to assess the methodologic quality of the other studies. DATA SYNTHESIS RCTs (n=10) and other clinical trials (n=11) were included. The methodologic quality of the RCTs was low, varying between 4 and 8 on the PEDro scale. All studies show great diversity at the levels of methodology, population, intervention, and outcome measures making a meta-analysis not feasible. Both manual and mechanical stretching methods were studied. Stretching protocols were generally inadequately described and poorly standardized. The outcome measures used often assessed impairments such as available range of motion but were unable to distinguish between neural and nonneural components of spasticity. Associated functional benefits were not usually investigated. Although there is some positive evidence supporting the immediate effects of 1 stretching session, it remains unclear how long these effects abide and its long-term consequences. CONCLUSIONS There is a wide diversity in studies investigating the effects of stretching on spasticity, and the available evidence on its clinical benefit is overall inconclusive. We recognize the need for consensus on a paradigm for stretching and for good-quality studies. Future research should address this issue and should investigate the clinical importance of the short- and long-term effects.

Functional MRI Correlates of Lower Limb Function in Stroke Victims With Gait Impairment

Background and Purpose— Although knowledge concerning cortical reorganization related to upper limb function after ischemic stroke is growing, similar data for lower limb movements are limited. Previous studies with hand movement suggested increasing recruitment of motor areas in the unlesioned hemisphere with increasing disability. We used ankle movement as a lower limb analog to test for similarities and differences in recovery patterns. Methods— Eighteen subjects were selected with chronic residual gait impairment due to a single subcortical ischemic stroke. Functional MRI scans were obtained at 3.0 T during active and passive ankle dorsiflexion in the patients (8 females, 10 males; mean age, 59.9±13.5 years; range, 32 to 74 years) and 18 age-matched healthy control subjects. Results— We observed substantial neocortical activity associated with foot movement both in the patients with stroke and in the healthy control subjects. Our primary finding was increased cortical activation with increasing functional impairment. The extent of activation (particularly in the primary sensorimotor cortex and the supplementary motor area of the unlesioned hemisphere) increased with disability. The changes were most prominent with the active movement task. Conclusions— Using ankle movement, we observed increased activation in the unlesioned hemisphere associated with worse function of the paretic leg, consistent with studies on movement of paretic upper limbs. We interpret this finding as potentially adaptive recruitment of undamaged ipsilateral motor control pathways from the supplementary motor area and (possibly maladaptive) disinhibition of the ipsilateral sensorimotor cortex.

A Pilot Randomized, Placebo Controlled, Double Blind Phase I Trial of the Novel SIRT1 Activator SRT2104 in Elderly Volunteers

Background SRT2104 has been developed as a selective small molecule activator of SIRT1, a NAD+-dependent deacetylase involved in the regulation of energy homeostasis and the modulation of various metabolic pathways, including glucose metabolism, oxidative stress and lipid metabolism. SIRT1 has been suggested as putative therapeutic target in multiple age-related diseases including type 2 diabetes and dyslipidemias. We report the first clinical trial of SRT2104 in elderly volunteers. Methods Oral doses of 0.5 or 2.0 g SRT2104 or matching placebo were administered once daily for 28 days. Pharmacokinetic samples were collected through 24 hours post-dose on days 1 and 28. Multiple pharmacodynamic endpoints were explored with oral glucose tolerance tests (OGTT), serum lipid profiles, magnetic resonance imaging (MRI) for assessment of whole body visceral and subcutaneous fat, maximal aerobic capacity test and muscle 31P magnetic resonance spectroscopy (MRS) for estimation of mitochondrial oxidative capacity. Results SRT2104 was generally safe and well tolerated. Pharmacokinetic exposure increased less than dose-proportionally. Mean Tmax was 2–4 hours with elimination half-life of 15–20 hours. Serum cholesterol, LDL levels and triglycerides decreased with treatment. No significant changes in OGTT responses were observed. 31P MRS showed trends for more rapid calculated adenosine diphosphate (ADP) and phosphocreatine (PCr) recoveries after exercise, consistent with increased mitochondrial oxidative phosphorylation. Conclusions SRT2104 can be safely administered in elderly individuals and has biological effects in humans that are consistent with SIRT1 activation. The results of this study support further development of SRT2104 and may be useful in dose selection for future clinical trials in patients. Trial Registration ClinicalTrials.gov NCT00964340

What effect does a structured home-based exercise programme have on people with Huntington’s disease? A randomized, controlled pilot study

Objective: The aim of this study was to explore feasibility, safety and outcome of an exercise intervention in people with Huntington’s disease. Design: A randomized controlled pilot trial. Setting: A home-based exercise programme. Subjects: A total of 25 subjects with early to mid-stage Huntington’s disease. Intervention: Subjects were randomly allocated to either an exercise intervention (n = 13) or a control group (n = 12). Subjects in the exercise intervention group were asked to perform exercises at home three times a week for eight weeks using an exercise DVD, specifically developed for this purpose. The control group received their usual care. Measures: Adherence in the intervention group was calculated from exercise diaries. Measures of gait, balance, function, level of physical activity and quality of life were evaluated. Analysis of covariance was used to compare follow-up scores across groups after adjustment for chance baseline differences. Effect sizes were calculated. Results: Eleven participants from the intervention and ten from the control group completed the study. Mean adherence was 29.4 SD 1.8 for the 32 prescribed sessions. There were no related adverse events. Differences between groups were observed in gait speed, balance, function and level of physical activity, but not quality of life as measured by the SF36. Effect sizes were large (>0.8) for the majority of the outcomes. Conclusions: Short-term structured home exercise programmes are feasible, beneficial and safe for people with early to mid-stage of Huntington’s disease. Our findings support the implementation of a larger trial of longer-term home exercise.

Exercise for multiple sclerosis: a single-blind randomized trial comparing three exercise intensities:

Background: The most effective exercise dose has yet to be established for multiple sclerosis (MS). Objective: The aim of this study was to investigate the effect of different exercise intensities in people with MS. Methods: We completed a randomized comparator study of three cycling exercise intensities, with blinded assessment, was carried out in Oxford. Sixty-one adults with MS who fulfilled inclusion criteria were randomized at entry into the study, using a computer-generated list held by an exercise professional, into either: continuous (at 45% peak power, n = 20), intermittent (30 sec on, 30 sec off at 90% peak power, n = 21) or combined (10 min intermittent at 90% peak power then 10 min continuous at 45% peak power, n = 20) exercise for 20 min twice a week for 12 weeks in a leisure facility. Groups were assessed at: baseline, halfway (6 weeks), end intervention (12 weeks) and follow-up (24 weeks). Primary outcome measure was 2 min walk. Results: Fifty-five participants were included in the analysis (n = continuous 20, intermittent 18, combined 17). No differences were found between groups. After 6 weeks, considering all participants, 2 min walk distance increased by 6.96 ± 2.56 m (95% CI: 1.81 to 12.10, effect size (es): 0.25, p < 0.01). The continuous group increased by 4.71 ± 4.24 m (95% CI: −3.80 to 13.22, es: 0.06), intermittent by 12.94 ± 4.71 m (95% CI: 3.97 to 21.92, es: 0.28) and combined by 3.22 ± 4.60 m (95% CI: −6.01 to 12.46, es: 0.04). Two minute walk did not significantly change between further assessments. Between 6 and 12 weeks there was a drop in attendance that seemed to be associated with the intermittent and combined groups; these groups also had a greater number of adverse events (leg pain during cycling most common) and dropouts (n = continuous 1, intermittent 5, combined 10). Considering all participants, 6 weeks of cycling exercise produced benefits in mobility that were maintained with further sessions. Conclusion: While no differences were found between groups, greater benefit may be associated with higher-intensity exercise, but this may be less well tolerated.CONSORT - trial registration number (ISRCTN89009719)

An Integrated Motor Imagery Program to Improve Functional Task Performance in Neurorehabilitation: A Single-Blind Randomized Controlled Trial

OBJECTIVE To investigate the feasibility of a motor imagery program integrated into physiotherapy and occupational therapy. DESIGN A parallel-group, phase II, assessor-blind randomized controlled trial comparing motor imagery embedded in usual therapy with usual therapy only. SETTING A neurologic rehabilitation center (Oxford, United Kingdom). PARTICIPANTS Inpatients and outpatients diagnosed with stroke, brain injury, or multiple sclerosis, participating in a rehabilitation program with sufficient language skills to undertake the intervention were recruited (N=30) and assessed at baseline, after 6 weeks (postintervention), and after 12 weeks (follow-up). INTERVENTIONS A motor imagery strategy was developed that could be integrated into usual therapy, tailored to individual goals, and used for any activity. The control group received standard care. MAIN OUTCOME MEASURES Goal attainment scaling was used as the primary outcome measure. Other measures included the Barthel activities of daily living index and the Rivermead Mobility Index. RESULTS Compliance with advised treatment was poor in 85% of the therapists and in 72% of the patients. Goal attainment scaling scores significantly improved at postintervention and follow-up (F(2,27)=45.159; P<.001), but no significant difference was observed between the groups over time (F(1,28)=.039; P=.845). CONCLUSIONS Therapist and patient compliance with performing the intervention was low, restricting the conclusions regarding the effectiveness of the integrated motor imagery program. Future studies will need to explore barriers and facilitators to uptake of this intervention in clinical practice. Trial recruitment and retention were good. The study demonstrated that imagery could be successfully integrated into usual therapy and tailored for a wide range of functional activities.