Surface Electromyographic Biofeedback and the Effortful Swallow Exercise for Stroke-Related Dysphagia and in Healthy Ageing.

Dysphagia is common after stroke, leading to adverse outcome. The Effortful Swallow (ES) is recommended to improve swallowing but it is not known if dysphagic patients can increase muscle activity during the exercise or if age affects performance. Providing surface electromyographic (sEMG) biofeedback during dysphagia therapy may enhance exercise completion, but this has not been investigated and the technique's acceptability to patients is not known. Aims: To determine if age or post-stroke dysphagia affect the ability to increase submental muscle activity during the ES, if sEMG biofeedback improves ES performance and if sEMG is an acceptable addition to therapy. In a Phase I study submental sEMG amplitudes were measured from 15 people with dysphagia < 3 months post-stroke and 85 healthy participants aged 18-89 years during swallowing (NS) and when they performed the ES with and without sEMG biofeedback. Participant feedback was collected via questionnaire. Measurements were compared with repeated measures ANOVA and age effects were examined with linear regression. Both groups produced significantly greater muscle activity for the ES than NS (p < 0.001) and significantly increased activity with biofeedback (p < 0.001) with no effect of age. Participant feedback about sEMG was very positive; over 98% would be happy to use it regularly. The ES is a physiologically beneficial dysphagia exercise, increasing muscle activity during swallowing. sEMG biofeedback further enhances performance and is considered an acceptable technique by patients. These findings support the potential application of sEMG biofeedback and the ES in dysphagia therapy in stroke, justifying further investigation of patient outcome.

Reliability of a Method to Measure Neck Surface Electromyography, Kinematics, and Pain Occurrence in Participants With Neck Pain.

OBJECTIVE: To investigate the reliability of a novel method to measure neck surface electromyography (SEMG), kinematics, and pain during active movements in participants with neck pain. METHODS: This test-retest study evaluated 23 participants with chronic neck pain. Each was measured twice within a single session. Three-dimensional kinematics and SEMG were recorded in 10° increments during forward and side flexion, extension, and rotation of the neck. Neck position during pain occurrence was also measured. RESULTS: Intraclass correlation coefficients were >0.80 for 96% and 100% of SEMG and kinematic data, respectively. The percentage of standard error of the measurement (SEM) values were <25% for 91% of all SEMG measures; most were <15%, and some were <10%. For ranges of motion in the primary plane, percentage of SEM values were all <6% (SEM 1°-3°). Intraclass correlation coefficients for neck position during pain occurrence were all >0.60, except for right rotation (0.48) (SEM values 2°-8°). Pain occurred approximately 59% to 75% into the total range of motion and persisted to its end. CONCLUSIONS: This methodology showed good reliability. It may be suitable for neck pain subclassification to evaluate the effects of treatment on pain, kinematics, and muscle activity during functional neck movements. The point of pain occurrence suggests increasing mechanical load on tissues may be one of the causative factors for movement-associated neck pain.

Self-perceived utilization of the paretic arm in chronic stroke requires high upper limb functional ability.

OBJECTIVE: To explore potential predictors of self-reported paretic arm use at baseline and after task-specific training (TST) in survivors of stroke. DESIGN: Data were obtained from a randomized controlled trial of somatosensory stimulation and upper limb TST in chronic stroke. SETTING: University laboratory. PARTICIPANTS: Chronic (≥3mo) survivors of stroke (N=33; mean age, 62y; mean stroke duration, 38mo). INTERVENTIONS: Participants received 12 sessions of TST preceded by either active (n=16) or sham (n=17) somatosensory stimulation to all 3 peripheral nerves. MAIN OUTCOME MEASURES: Demographic and clinical characteristics were entered stepwise into multiple linear regression analyses to determine the factors that best predict baseline Motor Activity Log (MAL) amount of use rating and change 3 months after TST. RESULTS: The Action Research Arm Test (ARAT) score predicted the amount of use at baseline (R(2)=.47, P<.001); in using this model, an ARAT score of 54 (maximum of 57) is required to score 2.5 on the MAL (use described as between rarely and sometimes). After TST the change in the ARAT score predicted the change in the amount of use (R(2)=.31, P=.001). The predictive power of the model for change at 3 months increased if the Fugl-Meyer Assessment wrist component score was added (R(2)=.41, P=.001). CONCLUSIONS: Utilization of the paretic upper limb in activities of daily living requires high functional ability. The increase in self-reported arm use after TST is dependent on the change in functional ability. These results provide further guidance for rehabilitation decisions.

Whole-body vibration in addition to strength and balance exercise for falls-related functional mobility of frail older adults: a single-blind randomized controlled trial.

OBJECTIVES: To investigate the effects of whole-body vibration in addition to an exercise programme on functional mobility and related outcomes for frail older fallers. DESIGN: Single-blind randomized parallel group trial. SETTING: UK; National Health Service assessment and rehabilitation facility for older people. PARTICIPANTS: Frail older fallers: 38 (80 ± 8.6 years) performed the exercise with whole-body vibration (vibration group), and 39 (82 ± 8.1 years) without (exercise group). INTERVENTION: Sixty minutes supervised exercise class three times weekly for eight weeks ± whole-body vibration (up to 5 × 1 minute, 15-30 Hz and 2-8 mm peak-to-peak). MEASUREMENTS: Timed Up and Go, 6-m walk, static balance, fear of falling (FES-I) and self-reported health status (SF-12 version 2) were assessed at baseline, four weeks (mobility measures only), eight weeks and six months. RESULTS: Timed Up and Go and 6-m walk improved in both groups at eight weeks (P < 0.01), but significantly more in the vibration group (timed up and go: 38 vs. 20%, P < 0.05); 6-m walk: (36 vs. 18.1%, P < 0.05, respectively). Balance, fear of falling and physical component of the self-reported health status improved similarly in both groups (P < 0.05). At follow-up, no significant differences from baseline remained for any measure. The mean total time experienced was 37% of maximal target. CONCLUSION: The addition of whole-body vibration to strength and balance exercise resulted in greater improvements in functional mobility than exercise alone, despite achieving lower than anticipated exposure. Gains from neither intervention were sustained at six months.

The effects of whole body vibration on balance, joint position sense and cutaneous sensation.

Whole body vibration (WBV) may enhance muscular strength and power but little is known about its influence on sensory-motor function. Vibration of a single muscle or tendon affects the afferent system in a manner that depends on amplitude and frequency. WBV stimulates many muscle groups simultaneously and the frequencies and amplitudes used are different from many of the studies on single musculotendinous units. We investigated the effects of WBV at two amplitudes on balance, joint position sense (JPS) and cutaneous sensation in young healthy subjects. Eighteen adults (24.3 ± 1.5 years, 15 females) were assessed before WBV (five 1 min bouts, 30 Hz) then immediately, 15 and 30 min afterwards. Two amplitudes (4 and 8 mm peak to peak) were investigated on different occasions. Standing balance was assessed with feet together and eyes closed, and standing on one leg with eyes open and closed. JPS at the knee and ankle was assessed by repositioning tasks while cutaneous sensation was recorded from six sites in the lower limb using pressure aesthesiometry. Neither amplitude affected JPS (P > 0.05). There were minimal effects on balance only in the vertical plane and only 30 min after WBV (P < 0.05). Low amplitude vibration only reduced sensation at the foot and ankle immediately after WBV (P < 0.008). High amplitude vibration impaired sensation at the foot, ankle and posterior shank for the entire test period (P < 0.008). In young healthy individuals WBV did not affect JPS or static balance, but reduced cutaneous sensation. These data may have implications for older and clinical populations with compromised postural control.

Immediate effects of cervical mobilisations on neck muscle activity during active neck movements in patients with non-specific neck pain. A double blind placebo controlled trial.

BACKGROUND: Cervical mobilisations are used to treat people with neck pain but their mechanisms of action are unclear. One theorised reason for induced analgesia is effect on neck muscle activity. OBJECTIVES: To assess the effects of cervical mobilisations on muscle activity during active neck movements and whether changes in muscle activity are associated with changes in symptoms. DESIGN: Double-blind randomised placebo controlled trial. SETTING: Primary care. PARTICIPANTS: 40 patients (aged 19 to 80 years, 24 female) with non-specific neck pain. INTERVENTIONS: One session of cervical mobilisations or motionless manual contact (placebo). MAIN OUTCOME MEASURES: sternocleidomastoid (SCM), scalene (SCA), upper trapezius (UT) and erector spinae (ES) surface electromyography (SEMG) during active neck flexion, extension, side flexion and rotation was measured immediately before and after the intervention. Patients were classified as responders according to change in symptoms assessed using the Global Rating of Change Scale (GROC). RESULTS: Compared with placebo, patients receiving mobilisation showed an increase in contralateral UT and ES SEMG during rotation and contralateral and ipsilateral SCM, SCA and UT during side flexion (P<0.05), however changes were mostly associated with an increase in range and speed of movement. The only association with GROC was increased (5%) SEMG in the contralateral SCM during side flexion in the mobilisation group (P=0.013). CONCLUSION: Cervical mobilisations caused increased neck SEMG, mostly due to increased movement range and speed. Change in muscle activity is unlikely to be a major mechanism of action of cervical mobilisations in symptomatic improvement with physiological neck movements. (ClinicalTrials.gov record number: 2016/066). CLINICAL TRIALS REGISTRY: ClinicalTrials.gov record number: 2016/066.

Effects of endurance and strength-directed electrical stimulation training on the performance and histological properties of paralyzed human muscle: a pilot study.

Electrical stimulation (ES) improves muscle properties after spinal cord injury (SCI), but cycling power output (PO) remains low. We investigated the effect of endurance and strength ES training on these parameters. Assessments of quadriceps strength and fatigue resistance, cycling PO, and muscle biopsies were made in four well-trained SCI subjects (three cyclists and one rower) before and after additional weight training in the cyclists and once in the rower. Weight training improved muscle strength, but cycling PO was low in all subjects. There was no effect of training type on biopsy data. Biopsies showed non-specific signs of pathology, predominance of type IIa fibers, and uniform metabolic activity. Oxidative activity was low, as were capillary:fiber ratios in the cyclists. Cycling PO is limited by factors other than muscle strength. Future ES training studies should attempt to improve muscle oxidative capacity to optimize the potential benefits of ES exercise.

Energy turnover in relation to slowing of contractile properties during fatiguing contractions of the human anterior tibialis muscle.

Slowing and loss of muscle power are major factors limiting physical performance but little is known about the molecular mechanisms involved. The slowing might be a consequence of slow detachment of cross bridges and, if this were the case, then a reduction in the ATP cost of an isometric contraction would be expected as the muscle fatigued. The human anterior tibialis muscle was stimulated repeatedly under ischaemic conditions at 50 Hz for 1.6 s with a 50% duty cycle and muscle metabolites measured by (31)P magnetic resonance spectroscopy. Over the course of 20 contractions the half-time of relaxation increased from 36.5 +/- 0.09 ms (mean +/- s.e.m.) to 113 +/- 17 ms and isometric force was reduced to 63 +/- 3% of the initial value. ATP turnover was determined from the change in high energy phosphates and lactate production, the latter estimated from the change of intracellular pH. ATP turnover over the first three contractions was 2.45 +/- 0.09 mM s(1) and decreased to 1.8 +/- 0.06 mm s(1) over the last five tetani. However, when this latter value was normalised for the decrease in isometric force, it became 2.56 +/- 0.3 mM s(1), which is the same as the turnover of the fresh muscle. The data suggest that the rate of cross bridge detachment is unaffected by fatigue and are consistent the suggestion that it is the rate of attachment which is slowed rather than the rate of detachment. The present results focus attention on stages in the cross bridge cycle concerned with attachment and the transition from low to high force states that may be influenced by metabolic changes in the fatiguing muscle.

Effect of patellofemoral pain on foot posture and walking kinematics.

Background Excessive pronation has been implicated in patellofemoral pain (PFP) aetiology and foot orthoses are commonly prescribed for PFP patients. Pronation can be assessed using foot posture tests, however, the utility of such tests depends on their association with foot and lower-limb kinematics. Research questions Do PFP participants compared with healthy participants (1) have a more pronated foot measured with static foot tests and a kinematic multi-segmental foot model and (2) is there an association between static foot posture and foot and lower limb kinematics during walking? Methods A case-control study including 22 participants (n = 11 PFP, 5 females per group, aged 24 ± 3 (mean ± SD) years) was conducted. Foot posture measures included Arch Height Ratio, Navicular Drop (ND), and Foot Posture Index. Between-group comparisons of foot posture, segment and joint angle magnitudes, and associations between foot posture and kinematic data during gait were evaluated. Results There were no group differences in foot posture tests and mean joint angles. PFP participants had greater internal rotation of the shank and rearfoot segments, and adduction of the mid- and forefoot in the transverse plane (all p < 0.05). Greater ND was associated with increased forefoot abduction (rho=-0.68, p = 0.02) in healthy participants but no relationships were found between foot posture and kinematics in PFP participants. Significance Foot posture and kinematic data did not indicate excessive pronation in PFP participants questioning the use of orthoses to correct pronation. Larger studies are needed to determine the utility of foot posture tests as indicators of gait abnormalities in PFP.

Association between sympathoexcitatory changes and symptomatic improvement following cervical mobilisations in participants with neck pain. A double blind placebo controlled trial.

BACKGROUND: sympathoexcitation observed with passive cervical mobilisations may imply activation of an endogenous pain inhibition system resulting in hypoalgesia. However, research is mostly in asymptomatic participants and there is very limited evidence of a relationship between sympathoexcitation and symptomatic improvement in people with clinical pain. OBJECTIVE: to investigate the effects of cervical mobilisations on the sympathetic nervous system in participants with neck pain, and to explore the relationship between symptomatic improvement and sympathoexcitation. DESIGN: double-blind randomised controlled trial. METHOD: 40 participants with neck pain (aged 20-69 years, 25 female) were randomly allocated to either cervical mobilisations or motionless placebo. Skin conductance was measured before, during, and after intervention. After interventions were completed, their credibility was assessed. Participants were classified as responders or non-responders according to global symptom change. RESULTS: participants receiving mobilisations were more likely to be classified as responders (odds ratio: 4.33, p = 0.03) and demonstrated greater change in most outcome measures of sympathoexcitation from baseline to during the intervention but not from during to after the intervention. There was no association between sympathoexcitation and symptomatic improvement. Mobilisations and placebo were equally credible. CONCLUSIONS: These findings suggest sympathoexcitatory changes may be caused by an orienting response unrelated to the activation of an endogenous pain inhibition system Alternatively, the observed lack of an association may be explained by the existence of various mechanisms for pain relief. This study used single outcome measures of sympathoexcitation and symptomatic improvement and other measures may reveal different things. CLINICALTRIALS. GOV NUMBER: M10/2016/095.

Aircrew Conditioning Programme Impact on +Gz Tolerance.

INTRODUCTION: Physical conditioning may improve aircrew performance during exposure to high +Gz acceleration, although few studies have directly assessed this. The present study investigated the effects of a 12-wk Aircrew Conditioning Programme (ACP) on markers of G tolerance. The ACP comprises aerobic and muscle strengthening exercise performed twice weekly and targets improved fitness and reduced injury risk.METHODS: There were 36 UK Royal Air Force and Royal Navy aircrew who volunteered; 17 performed the ACP (Ex) and 19 acted as a control group (Con). Centrifuge testing was performed before and after the intervention. Relaxed G tolerance (RGT) and straining G tolerance (SGT), which had the addition of muscle tensing, were assessed. G endurance was also determined via repeated simulated air combat maneuvers (SACMs). During these centrifuge runs a number of physiological variables were recorded.RESULTS: During the G profile to determine RGT, neither RGT, HR, nor blood pressure responses were affected by the ACP. During SGT profiles, a lower HR at a given +Gz (+5.5 Gz) level following the ACP was observed (Ex: pre 146.0 ± 4.4, post 136.9 ± 5.6 bpm; Con: pre 148.0 ± 3.2, post 153.1 ± 3.3 bpm). BP was maintained and there was a tendency toward an improved SGT. The ACP increased the proportion of individuals completing the number of SACM profiles, although no meaningful differences were found between groups in other variables.CONCLUSION: Overall the ACP has no negative effect on RGT, reduced the physiological strain associated with a given level of +Gz (during SGT), and tended to improve the ability to tolerate repeated Gz exposure.Slungaard E, Pollock RD, Stevenson AT, Green NDC, Newham DJ, Harridge SDR. Aircrew conditioning programme impact on +Gz tolerance. Aerosp Med Hum Perform. 2019; 90(9):764-773.

Lower Body Acceleration and Muscular Responses to Rotational and Vertical Whole-Body Vibration at Different Frequencies and Amplitudes.

AIM: The aim of this study was to characterize acceleration transmission and neuromuscular responses to rotational vibration (RV) and vertical vibration (VV) at different frequencies and amplitudes. METHODS: Twelve healthy males completed 2 experimental trials (RV vs VV) during which vibration was delivered during either squatting (30°; RV vs VV) or standing (RV only) with 20, 25, and 30 Hz, at 1.5 and 3.0 mm peak-to-peak amplitude. Vibration-induced accelerations were assessed with triaxial accelerometers mounted on the platform and bony landmarks at ankle, knee, and lumbar spine. RESULTS: At all frequency/amplitude combinations, accelerations at the ankle were greater during RV (all P < .03) with the greatest difference observed at 30 Hz, 1.5 mm. Transmission of RV was also influenced by body posture (standing vs squatting, P < .03). Irrespective of vibration type, vibration transmission to all skeletal sites was generally greater at higher amplitudes but not at higher frequencies, especially above the ankle joint. Acceleration at the lumbar spine increased with greater vibration amplitude but not frequency and was highest with RV during standing. CONCLUSIONS/IMPLICATIONS: The transmission of vibration during whole-body vibration (WBV) is dependent on intensity and direction of vibration as well as body posture. For targeted mechanical loading at the lumbar spine, RV of higher amplitude and lower frequency vibration while standing is recommended. These results will assist with the prescription of WBV to achieve desired levels of mechanical loading at specific sites in the human body.

Explicit motor sequence learning with the paretic arm after stroke.

PURPOSE: Motor sequence learning is important for stroke recovery, but experimental tasks require dexterous movements, which are impossible for people with upper limb impairment. This makes it difficult to draw conclusions about the impact of stroke on learning motor sequences. We aimed to test a paradigm requiring gross arm movements to determine whether stroke survivors with upper limb impairment were capable of learning a movement sequence as effectively as age-matched controls. MATERIALS AND METHODS: In this case-control study, 12 stroke survivors (10-138 months post-stroke, mean age 64 years) attempted the task once using their affected arm. Ten healthy controls (mean 66 years) used their non-dominant arm. A sequence of 10 movements was repeated 25 times. The variables were: time from target illumination until the cursor left the central square (onset time; OT), accuracy (path length), and movement speed. RESULTS: OT reduced with training (p < 0.05) for both groups, with no change in movement speed or accuracy (p > 0.1). We quantified learning as the OT difference between the end of training and a random sequence; this was smaller for stroke survivors than controls (p = 0.015). CONCLUSIONS: Stroke survivors can learn a movement sequence with their paretic arm, but demonstrate impairments in sequence specific learning. Implications for Rehabilitation Motor sequence learning is important for recovery of movement after stroke. Stroke survivors were found to be capable of learning a movement sequence with their paretic arm, supporting the concept of repetitive task training for recovery of movement. Stroke survivors showed impaired sequence specific learning in comparison with age-matched controls, indicating that they may need more repetitions of a sequence in order to re-learn movements. Further research is required into the effect of lesion location, time since stroke, hand dominance and gender on learning of motor sequences after stroke.

Differences in neck surface electromyography, kinematics and pain occurrence during physiological neck movements between neck pain and asymptomatic participants. A cross-sectional study.

BACKGROUND: Neck pain has been associated with altered muscle activity and impaired kinematics. Patients frequently report pain during physiological neck movements. Previously, the average muscle activity during these movements has been measured. However, muscle activity is modulated by the position in the range of movement, hence the study of neck muscle activity in discrete sections of the range of movement is warranted. Evidence is conflicting regarding range of movement restriction in neck pain. No study has assessed the point in the range of movement at which pain occurs. This study aimed to investigate neck kinematics, muscle activity and pain during physiological neck movements in participants with and without neck pain. METHODS: Neck kinematics and surface electromyography were recorded continuously and analysed in 10° increments during forward and side flexion, extension and rotation of the neck in 20 neck pain and 20 asymptomatic participants. Point of pain occurrence in the range of movement was recorded. FINDINGS: Neck pain participants demonstrated significantly lower activity of scalene during flexion and extension, and a non-significant higher activity in sternocleidomastoids during rotation. No differences in neck kinematics were observed. 65% of neck pain participants reported pain during at least one neck movement. Pain was reported in the last ≈20-40% of the range of movement. INTERPRETATION: Exercises used in current practice to minimise scalene activity may not be appropriate for all neck pain patients. Restricted range of movement is not a consistent feature of neck pain. Movement associated neck pain is present at the end of range of movement, which has implications for the study of neck pain and rehabilitation.

Content Validity of Level Two of the Royal Air Force Aircrew Conditioning Programme.

INTRODUCTION: The prevalence of flight-related neck pain in all Royal Air Force (RAF) aircrew is 66% and 70% in UK fast-jet aircrew. The RAF Aircrew Conditioning Programme (ACP) has been designed to enhance pilot performance through reducing fatigue and strain injuries, particularly to the neck. Content validity of the ACP was assessed to determine the appropriateness for delivery to aircrew. METHODS: Six international medical experts reviewed level two of the ACP, which is delivered to student aircrew who have completed basic instruction in cervical spine stability, core stability and initial technique instruction for strength training. Content validity on overall exercise approach (5 items) and specific exercise session (24 items) was rated on a 4-point Likert-type ordinal scale for Relevance and Simplicity. Four reviewers had experience of delivering an exercise program to aircrew. The item-content validity index (I-CVI) was the proportion of experts rating an item/exercise as acceptable (score 3-4) while protocol-CVI was the average I-CVI across items. RESULTS: Of the suggested exercise sessions, 20 reached an excellent I-CVI (1.00) for Relevance (4 reached acceptable I-CVI (0.83)), and 21 reached an excellent I-CVI (1.00) for Simplicity (3 reached acceptable I-CVI (0.83)). Protocol-CVI for the ACP was excellent for Relevance (0.90) and good for Simplicity (0.83). The need for sufficient supervision during the exercises was recommended for safe exercise execution and to maintain adherence. CONCLUSION: The ACP demonstrated excellent relevance for the target population. The aircrew require additional supervision with the more complex neck exercises to enhance simplicity with the ACP.Slungaard E, Green NDC, Newham DJ, Harridge SDR. Content validity of level two of the Royal Air Force Aircrew Conditioning Program. Aerosp Med Hum Perform. 2018; 89(10):896-904.

Immediate effects of cervical mobilisations on global perceived effect, movement associated pain and neck kinematics in patients with non-specific neck pain. A double blind placebo randomised controlled trial.

BACKGROUND: Neck pain is prevalent, costly and disabling. Cervical mobilisations are frequently used to treat it but their effectiveness has been questioned by several systematic reviews. Evidence suggests that better outcomes are achieved with mobilisations when they are applied to specific patient subgroups. A criteria for patients suitable for neck mobilisations has been proposed, but the effectiveness on this patient subgroup has not been tested. OBJECTIVE: To assess the effectiveness of cervical mobilisations applied to a subgroup of patients with neck pain who fulfil specific criteria. DESIGN: Randomised controlled trial. METHOD: 40 patients with neck pain attending a Physiotherapy clinic were recruited and randomised to a single session of either cervical mobilisations or motionless manual contact placebo. The immediate effects on global perceived effect, range of movement (ROM), movement velocity and movement associated pain were assessed. RESULTS: mobilisation participants reported significantly better global perceived effect (p˂0.001) and improvements in movement associated pain (p = 0.041). Mobilisations produced a significant increase in ROM in side flexion (p = 0.006) and rotation (p = 0.044) when compared with placebo, but only in patients with pre-intervention ROM restriction. 29-47% of all movement associated pains were resolved following mobilisations and 11-27% following placebo. Patients in both groups showed a significant (p < 0.05) increase in movement velocity, but only in those who had a velocity restriction pre-intervention. CONCLUSIONS: Cervical mobilisations are effective in improving movement-associated pain, increasing ROM and velocity, and patient perceived improvement when applied to patients with neck pain that fulfil a criteria. Their use should be advocated.

Fatigue and functional performance of human biceps muscle following concentric or eccentric contractions.

A long-lasting fatigue was measured in human biceps muscle, following 40 maximal isokinetic concentric or eccentric contractions of the forearm, as the response to single-shock stimuli every minute for 4 h. This protocol allowed new observations on the early time course of long-lasting fatigue. Concentric contractions induced a novel progressive decline to 30.2% (SE 7.8, n = 7) of control at 23 min with complete recovery by 120 min. Eccentric contractions lead initially to a smaller force reduction of similar time course followed by a slower decline to 40.0% (SE 5.1, n = 7) control at 120 min with recovery less than half complete at 4 h. A 50-Hz test stimuli overcame both fatigues, identifying low-frequency fatigue. EMG recordings from the biceps muscle showed moderate (<20%) changes during the fatigue. A visual-tracking task showed no decrement in performance at the time of maximal fatigue of the single-shock response. Because the eccentric contractions have a similar activation, a larger force, but much smaller metabolic usage than concentric contractions, it is concluded that the initial decline is related to the effects of metabolites, whereas the slower phase after eccentric contractions is associated with higher mechanical stress.

Transcutaneous electrical nerve stimulation vs. transcutaneous spinal electroanalgesia for chronic pain associated with breast cancer treatments.

Chronic pain associated with breast cancer treatment is becoming increasingly recognized. Patients with this condition can experience significant physical and psychological morbidity and may benefit from nonpharmacological interventions as part of a multidisciplinary team approach. We compared the effectiveness of transcutaneous electrical nerve stimulation (TENS), transcutaneous spinal electroanalgesia (TSE), and a placebo (sham TSE) in a randomized controlled trial. The study sample comprised 41 women with chronic pain following breast cancer treatment, and outcome measures included pain report, pain relief, pain interference, anxiety and depression, arm mobility, and analgesic consumption. There was little evidence to suggest that TENS or TSE were more effective than placebo. All three interventions had beneficial effects on both pain report and quality of life, a finding that may be due to either psychophysical improvements resulting from the personal interaction involved in the treatment or a placebo response. Although electrical stimulation appears to be well tolerated in this population, further research is needed to establish its effectiveness for chronic cancer treatment-related pain.

Non-invasive brain stimulation for the lower limb after stroke: what do we know so far and what should we be doing next?

BACKGROUND: Non-invasive brain stimulation (NIBS) is promising as an adjuvant to rehabilitation of motor function after stroke. Despite numerous studies and reviews for the upper limb, NIBS targeting the lower limb and gait recovery after stroke is a newly emerging field of research. PURPOSE: To summarize findings from studies using NIBS to target the lower limb in stroke survivors. METHODS: This narrative review describes studies of repetitive transcranial magnetic stimulation, paired associative stimulation and transcranial direct current stimulation with survivors of stroke. RESULTS: NIBS appears capable of inducing changes in cortical excitability and lower limb function, but stimulation parameters and study designs vary considerably making it difficult to determine effectiveness. CONCLUSIONS: Future research should systematically assess differences in response with different stimulation parameters, test measures for determining who would be most likely to benefit and assess effectiveness with large samples before NIBS can be considered for use in clinical practice. Implications for Rehabilitation Stroke is a leading cause of disability, often resulting in dependency in activities of daily living and reduced quality of life. Non-invasive brain stimulation has received considerable interest as a potential adjuvant to rehabilitation after stroke and this review summarizes studies targeting the lower limb and gait recovery. Non-invasive brain stimulation can be used to modulate excitability of lower limb muscle representations and can lead to improvements in motor performance in stroke survivors. Non-invasive brain stimulation for gait recovery needs further investigation before translation to clinical practice is possible.

The effect of transcranial direct current stimulation on motor sequence learning and upper limb function after stroke.

OBJECTIVE: To assess the impact of electrode arrangement on the efficacy of tDCS in stroke survivors and determine whether changes in transcallosal inhibition (TCI) underlie improvements. METHODS: 24 stroke survivors (3-124months post-stroke) with upper limb impairment participated. They received blinded tDCS during a motor sequence learning task, requiring the paretic arm to direct a cursor to illuminating targets on a monitor. Four tDCS conditions were studied (crossover); anodal to ipsilesional M1, cathodal to contralesional M1, bihemispheric, sham. The Jebsen Taylor hand function test (JTT) was assessed pre- and post-stimulation and TCI assessed as the ipsilateral silent period (iSP) duration using transcranial magnetic stimulation. RESULTS: The time to react to target illumination reduced with learning of the movement sequence, irrespective of tDCS condition (p>0.1). JTT performance improved after unilateral tDCS (anodal or cathodal) compared with sham (p<0.05), but not after bihemispheric (p>0.1). There was no effect of tDCS on change in iSP duration (p>0.1). CONCLUSIONS: Unilateral tDCS is effective for improving JTT performance, but not motor sequence learning. SIGNIFICANCE: This has implications for the design of future clinical trials.