Effects of intensive physical rehabilitation on neuromuscular adaptations in adults with poststroke hemiparesis

Associations Between Time After Stroke and Exercise Training Outcomes: A Meta-Regression Analysis

Background Knowledge gaps exist regarding the effect of time elapsed after stroke on the effectiveness of exercise training interventions, offering incomplete guidance to clinicians. Methods and Results To determine the associations between time after stroke and 6-minute walk distance, 10-meter walk time, cardiorespiratory fitness and balance (Berg Balance Scale score [BBS]) in exercise training interventions, relevant studies in post-stroke populations were identified by systematic review. Time after stroke as continuous or dichotomized (≤3 months versus >3 months, and ≤6 months versus >6 months) variables and weighted mean differences in postintervention outcomes were examined in meta-regression analyses adjusted for study baseline mean values (pre-post comparisons) or baseline mean values and baseline control-intervention differences (controlled comparisons). Secondary models were adjusted additionally for mean age, sex, and aerobic exercise intensity, dose, and modality. We included 148 studies. Earlier exercise training initiation was associated with larger pre-post differences in mobility; studies initiated ≤3 months versus >3 months after stroke were associated with larger differences (weighted mean differences [95% confidence interval]) in 6-minute walk distance (36.3 meters; 95% CI, 14.2-58.5), comfortable 10-meter walk time (0.13 m/s; 95% CI, 0.06-0.19) and fast 10-meter walk time (0.16 m/s; 95% CI, 0.03-0.3), in fully adjusted models. Initiation ≤3 months versus >3 months was not associated with cardiorespiratory fitness but was associated with a higher but not clinically important Berg Balance Scale score difference (2.9 points; 95% CI, 0.41-5.5). In exercise training versus control studies, initiation ≤3 months was associated with a greater difference in only postintervention 6-minute walk distance (baseline-adjusted 27.3 meters; 95% CI, 6.1-48.5; fully adjusted, 24.9 meters; 95% CI, 0.82-49.1; a similar association was seen for ≤6 months versus >6 months after stroke (fully adjusted, 26.6 meters; 95% CI, 2.6-50.6). Conclusions There may be a clinically meaningful benefit to mobility outcomes when exercise is initiated within 3 months and up to 6 months after stroke.

Influence of the Passive Stabilization of the Trunk and Upper Limb on Selected Parameters of the Hand Motor Coordination, Grip Strength and Muscle Tension, in Post-Stroke Patients

Objective: Assessment of the influence of a stable trunk and the affected upper limb (dominant or non-dominant) on the parameters of the wrist and hand motor coordination, grip strength and muscle tension in patients in the subacute post-stroke stage compared to healthy subjects. Design: An observational study. Setting: Stroke Rehabilitation Department. Subjects: Thirty-four subjects after ischemic cerebral stroke and control group-32 subjects without neurological deficits, age and body mass/ height matched were included. Main measures: The tone of the multifidus, transverse abdominal and supraspinatus muscles were assessed by Luna EMG device. A HandTutor device were used to measure motor coordination parameters (e.g., range of movement, frequency of movement), and a manual dynamometer for measuring the strength of a hand grip. Subjects were examined in two positions: sitting without back support (non-stabilized) and lying with stabilization of the trunk and the upper limb. Results: Passive stabilization of the trunk and the upper extremity caused a significant improvement in motor coordination of the fingers (p ˂ 0.001) and the wrist (p < 0.001) in patients after stroke. Improved motor coordination of the upper extremity was associated with an increased tone of the supraspinatus muscle. Conclusions: Passive stabilization of the trunk and the upper limb improved the hand and wrist coordination in patients following a stroke. Placing patients in a supine position with the stability of the affected upper limb during rehabilitation exercises may help them to access latent movement patterns lost due to neurological impairment after a stroke.

Can Exercise-Induced Muscle Damage Be a Good Model for the Investigation of the Anti-Inflammatory Properties of Diet in Humans?

Subclinical, low-grade, inflammation is one of the main pathophysiological mechanisms underlying the majority of chronic and non-communicable diseases. Several methodological approaches have been applied for the assessment of the anti-inflammatory properties of nutrition, however, their impact in human body remains uncertain, because of the fact that the majority of the studies reporting anti-inflammatory effect of dietary patterns, have been performed under laboratory settings and/or in animal models. Thus, the extrapolation of these results to humans is risky. It is therefore obvious that the development of an inflammatory model in humans, by which we could induce inflammatory responses to humans in a regulated, specific, and non-harmful way, could greatly facilitate the estimation of the anti-inflammatory properties of diet in a more physiological way and mechanistically relevant way. We believe that exercise-induced muscle damage (EIMD) could serve as such a model, either in studies investigating the homeostatic responses of individuals under inflammatory stimuli or for the estimation of the anti-inflammatory or pro-inflammatory potential of dietary patterns, foods, supplements, nutrients, or phytochemicals. Thus, in this review we discuss the possibility of exercise-induced muscle damage being an inflammation model suitable for the assessment of the anti-inflammatory properties of diet in humans.

Impact of Lower Limb Active Movement Training in Individuals With Spastic Type Cerebral Palsy on Neuromuscular Control Outcomes: A Systematic Review

Background: Cerebral Palsy (CP) is a non-progressive neurological condition that results in motor impairment which increases proximally to distally along the lower extremity (i.e., greatest impairment at the ankle). Consequently, motor impairment and reduced voluntary muscle activation results in reduced neuromuscular control of the lower limb in this population. CP rehabilitation traditionally aims to improve movement proficiency for functional activities, such as walking, by using a range of active movement modalities that require volitional effort; however, the underlying neural mechanisms of improved control and function remain unknown. The primary purpose of this study was to systematically determine the efficacy of lower limb active movement interventions to improve neuromuscular control in individuals with CP.

Methodology: A search for studies involving an active lower limb intervention and neurophysiological outcome measures in individuals with CP was performed in five electronic databases. Studies were assessed for methodological quality using the Downs and Black assessment tool.

Results: Nine of 6,263 articles met the inclusion criteria. Methodological quality of all studies was poor, ranging from 2 to 27 out of a possible score of 32 points on the Downs and Black assessment tool. The study interventions varied extensively in modality and prescription as well as in the outcome measures used.

Conclusions: Whether active movement improves neuromuscular control of the lower limb in CP is unclear due to high variability in intervention protocols and selected outcomes measures. Future active intervention studies must carefully consider the selection of neurophysiological outcome measures.

Hand strengthening exercises in chronic stroke patients: Dose-response evaluation using electromyography

STUDY DESIGN

Cross-sectional.

PURPOSE OF THE STUDY

This study evaluates finger flexion and extension strengthening exercises using elastic resistance in chronic stroke patients.

METHODS

Eighteen stroke patients (mean age: 56.8 ± 7.6 years) with hemiparesis performed 3 consecutive repetitions of finger flexion and extension, using 3 different elastic resistance levels (easy, moderate, and hard). Surface electromyography was recorded from the flexor digitorum superficialis (FDS) and extensor digitorum (ED) muscles and normalized to the maximal electromyography of the non-paretic arm.

RESULTS

Maximal grip strength was 39.2 (standard deviation: 12.5) and 7.8 kg (standard deviation: 9.4) in the nonparetic and paretic hand, respectively. For the paretic hand, muscle activity was higher during finger flexion exercise than during finger extension exercise for both ED (30% [95% confidence interval {CI}: 19-40] vs 15% [95% CI: 5-25] and FDS (37% [95% CI: 27-48] vs 24% [95% CI: 13-35]). For the musculature of both the FDS and ED, no dose-response association was observed for resistance and muscle activity during the flexion exercise (P > .05).

CONCLUSION

The finger flexion exercise showed higher muscle activity in both the flexor and extensor musculature of the forearm than the finger extension exercise. Furthermore, greater resistance did not result in higher muscle activity during the finger flexion exercise. The present results suggest that the finger flexion exercise should be the preferred strengthening exercise to achieve high levels of muscle activity in both flexor and extensor forearm muscles in chronic stroke patients. The finger extension exercise may be performed with emphasis on improving neuromuscular control.

LEVEL OF EVIDENCE

4b.

Muscle power, contraction velocity and functional performance after stroke

OBJECTIVE

The goal of this study was to describe muscle function deficit in patients after stroke as well as to define the relationship between maximal muscle power (P_max ) and optimal shortening velocity (υ_opt ) with functional efficiency in stroke survivors.

MATERIAL AND METHODS

A total of 134 participants were enrolled in the study, including 67 patients after a stroke and 67 volunteers, matched for age and sex (controls). Functional performance was measured with the timed Up and Go test (TUG) and additionally with Rivermead Motor Assessment (RMA) and Barthel Index (BI) in stroke survivors. To assess P_max and υ_opt of the knee extensor muscles, a specially equipped Monark cycle ergometer was used.

RESULTS

The power generated by stroke survivors was 49.6% that of their peers and muscle contraction velocity was 65.5%. P_max /kg and υ_opt were associated with TUG outcomes in both groups. P_max /kg and υ_opt were associated with age in the control group, but not in patients after stroke. In multivariate analysis in patients after stroke, TUG was better predicted by P_max /kg or υ_opt than by the age. In stroke survivors, both P_max /kg and υ_opt were related to the BI and to the RMA total results. Both BI and RMA total were not determined by age.

CONCLUSIONS

Muscle power and muscle contraction velocity in patients who have had a stroke within three months have reduced markedly. These factors significantly affect functional performance. Muscle power and optimal shortening velocity are more important determinants of functional status than age in these stroke survivors.

Effects of high-intensity physical training on muscle fiber characteristics in poststroke patients

INTRODUCTION

Stroke is a leading cause of disability worldwide. High-intensity physical training can improve muscle strength and gait speed, but adaptive mechanisms at the muscle cellular level are largely unknown.

METHODS

Outpatients with poststroke hemiparesis participated in a 3-month rehabilitation program combining high-intensity strength and body-weight supported treadmill-training. Biopsies sampled bilaterally from vastus lateralis muscles, before, after, and at 1-year follow-up after intervention, were analyzed for fiber size, type, and capillarization.

RESULTS

At baseline, paretic lower limbs had smaller muscle fiber size and lower type I and IIA and higher type IIX percentages than nonparetic lower limbs. Paretic lower limbs had increased type IIA fibers after training. At follow-up, no difference between the lower limbs remained.

CONCLUSIONS

Although high-intensity training appeared not to induce changes in fiber size or capillarization, increased type IIA fiber percentages may contribute to muscle power and endurance, which is crucial for functional capacity. Muscle Nerve 56: 954-962, 2017.

Focusing on Increasing Velocity during Heavy Resistance Knee Flexion Exercise Boosts Hamstring Muscle Activity in Chronic Stroke Patients

Background. Muscle strength is markedly reduced in stroke patients, which has negative implications for functional capacity and work ability. Different types of feedback during strength training exercises may alter neuromuscular activity and functional gains. Objective. To compare levels of muscle activity during conditions of blindfolding and intended high contraction speed with a normal condition of high-intensity knee flexions. Methods. Eighteen patients performed unilateral machine knee flexions with a 10-repetition maximum load. Surface electromyography (EMG) was recorded from the quadrics and hamstring muscles and normalized to maximal EMG (nEMG) of the nonparetic limb. Results. For the paretic leg, the speed condition showed higher values of muscle activity compared with the normal and blindfolded conditions for both biceps femoris and semitendinosus. Likewise, the speed condition showed higher co-contraction values compared with the normal and blindfolded conditions for the vastus lateralis. No differences were observed between exercise conditions for the nonparetic leg. Conclusion. Chronic stroke patients are capable of performing heavy resistance training with intended high speed of contraction. Focusing on speed during the concentric phase elicited higher levels of muscle activity of the hamstrings compared to normal and blindfolded conditions, which may have implications for regaining fast muscle strength in stroke survivors.

Muscle, functional and cognitive adaptations after flywheel resistance training in stroke patients: a pilot randomized controlled trial

BACKGROUND

Resistance exercise (RE) improves neuromuscular function and physical performance after stroke. Yet, the effects of RE emphasizing eccentric (ECC; lengthening) actions on muscle hypertrophy and cognitive function in stroke patients are currently unknown. Thus, this study explored the effects of ECC-overload RE training on skeletal muscle size and function, and cognitive performance in individuals with stroke.

METHODS

Thirty-two individuals with chronic stroke (≥6 months post-stroke) were randomly assigned into a training group (TG; n = 16) performing ECC-overload flywheel RE of the more-affected lower limb (12 weeks, 2 times/week; 4 sets of 7 maximal closed-chain knee extensions; <2 min of contractile activity per session) or a control group (CG; n = 16), maintaining daily routines. Before and after the intervention, quadriceps femoris volume, maximal force and power for each leg were assessed, and functional and dual task performance, and cognitive functions were measured.

RESULTS

Quadriceps femoris volume of the more-affected leg increased by 9.4 % in TG. Muscle power of the more-affected, trained (48.2 %), and the less-affected, untrained limb (28.1 %) increased after training. TG showed enhanced balance (8.9 %), gait performance (10.6 %), dual-task performance, executive functions (working memory, verbal fluency tasks), attention, and speed of information processing. CG showed no changes.

CONCLUSION

ECC-overload flywheel resistance exercise comprising 4 min of contractile activity per week offers a powerful aid to regain muscle mass and function, and functional performance in individuals with stroke. While the current intervention improved cognitive functions, the cause-effect relationship, if any, with the concomitant neuromuscular adaptations remains to be explored.

TRIAL REGISTRATION

Clinical Trials NCT02120846.

Effects of Vibration Intensity, Exercise, and Motor Impairment on Leg Muscle Activity Induced by Whole-Body Vibration in People With Stroke

BACKGROUND

Whole-body vibration (WBV) has increasingly been used as an adjunct treatment in neurological rehabilitation. However, how muscle activation level changes during exposure to different WBV protocols in individuals after stroke remains understudied.

OBJECTIVE

The purpose of this study was to examine the influence of WBV intensity on the magnitude of biceps femoris (BF) and tibialis anterior (TA) muscle activity and its interaction with exercise and with severity of motor impairment and spasticity among individuals with chronic stroke.

METHODS

Each of the 36 individuals with chronic stroke (mean age=57.3 years, SD=10.7) performed 8 different static exercises under 3 WBV conditions: (1) no WBV, (2) low-intensity WBV (frequency=20 Hz, amplitude=0.60 mm, peak acceleration=0.96g), and (3) high-intensity WBV (30 Hz, 0.44 mm, 1.61g). The levels of bilateral TA and BF muscle activity were recorded using surface electromyography (EMG).

RESULTS

The main effect of intensity was significant. Exposure to the low-intensity and high-intensity protocols led to a significantly greater increase in normalized BF and TA muscle electromyographic magnitude in both legs compared with no WBV. The intensity × exercise interaction also was significant, suggesting that the WBV-induced increase in EMG activity was exercise dependent. The EMG responses to WBV were similar between the paretic and nonparetic legs and were not associated with level of lower extremity motor impairment and spasticity.

LIMITATIONS

Leg muscle activity was measured during static exercises only.

CONCLUSIONS

Adding WBV during exercise significantly increased EMG activity in the TA and BF muscles. The EMG responses to WBV in the paretic and nonparetic legs were similar and were not related to degree of motor impairment and spasticity. The findings are useful for guiding the design of WBV training protocols for people with stroke.

Electromyographic Comparison of Elastic Resistance and Machine Exercises for High-Intensity Strength Training in Patients With Chronic Stroke

OBJECTIVE

To investigate whether elastic resistance training can induce comparable levels of muscle activity as conventional machine training in patients with chronic stroke.

DESIGN

Comparative study.

SETTING

Outpatient rehabilitation facility.

PARTICIPANTS

Stroke patients (N=18) with hemiparesis (mean age, 57 ± 8y).

INTERVENTIONS

Patients performed 3 consecutive repetitions at 10 repetition maximum of unilateral knee extension and flexion using elastic resistance and conventional machine training.

MAIN OUTCOME MEASURES

Surface electromyography was measured in vastus lateralis, vastus medialis, biceps femoris, and semitendinosus and was normalized to maximal electromyography (% of max) of the nonparetic leg.

RESULTS

In the paretic leg, agonist muscle activity ranged from 18% to 24% normalized electromyography (% of max) (nEMG) during knee flexion and from 32% to 40% nEMG during knee extension. For knee extension, vastus lateralis nEMG was higher during machine exercise than during elastic resistance exercise (40% [95% confidence interval {CI}, 33-47] vs 32% [95% CI, 25-39]; P=.003). In the nonparetic leg, agonist muscle activity ranged from 54% to 61% during knee flexion and from 52% to 68% during knee extension. For knee flexion semitendinosus nEMG was higher (61% [95% CI, 50-71] vs 54% [95% CI, 44-64]; P=.016) and for knee extension vastus medialis nEMG was higher (68% [95% CI, 60-76] vs 56% [95% CI, 48-64]; P<.001) during machine exercise than during elastic resistance exercise. By contrast, antagonist coactivation was significantly higher during knee flexion when performed using elastic resistance compared with the machine. Lastly, there were no differences in perceived exertion between exercise modalities.

CONCLUSIONS

Machine training appears to induce slightly higher levels of muscle activity in some of the investigated muscles compared to elastic resistance during lower limb strength training in patients with chronic stroke. The higher level of coactivation during knee flexion when performed using elastic resistance suggests that elastic resistance exercises are more difficult to perform. This is likely due to a higher level of movement instability.

Dose-response association between leisure time physical activity and work ability: Cross-sectional study among 3000 workers

INTRODUCTION

Regular physical activity is important for longevity and health, but knowledge about the optimal dose of physical activity for maintaining good work ability is unknown. This study investigates the association between intensity and duration of physical activity during leisure time and work ability in relation to physical demands of the job.

METHODS

From the 2010 round of the Danish Work Environment Cohort Study, currently employed wage earners with physically demanding work (n = 2952) replied to questions about work, lifestyle and health. Excellent (100 points), very good (75 points), good (50 points), fair (25 points) and poor (0 points) work ability in relation to the physical demands of the job was experienced by 18%, 40%, 30%, 10% and 2% of the respondents, respectively.

RESULTS

General linear models that controlled for gender, age, physical and psychosocial work factors, lifestyle and chronic disease showed that the duration of high-intensity physical activity during leisure was positively associated with work ability, in a dose-response fashion (p < 0.001). Those performing ⩾ 5 hours of high-intensity physical activity per week had on average 8 points higher work ability than those not performing such activities. The duration of low-intensity leisure-time physical activity was not associated with work ability (p = 0.5668).

CONCLUSIONS

The duration of high-intensity physical activity during leisure time is associated in a dose-response fashion with work ability, in workers with physically demanding jobs.

Chronic stroke patients show early and robust improvements in muscle and functional performance in response to eccentric-overload flywheel resistance training: a pilot study

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 (~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°/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°/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.

Eccentric Versus Concentric Resistance Training to Enhance Neuromuscular Activation and Walking Speed Following Stroke

Background. Impaired voluntary neuromuscular activation of agonist muscles is a primary determinant of weakness and motor dysfunction following stroke. Objective. To determine whether eccentric resistance training (ECC) resistance training is superior to concentric resistance training (CON) resistance training to enhance neuromuscular activation, strength, and walking speed after stroke. Methods. A total of 34 adults poststroke participated in a staged intervention comprising (1) either CON-only or ECC-only resistance training of the paretic leg followed by (2) gait training. Changes in voluntary neuromuscular activation and power were assessed for both the trained paretic and untrained nonparetic legs. Self-selected and fast walking speeds were also assessed. Results. In response to resistance training, the ECC group experienced larger improvements in neuromuscular activation of paretic leg muscles, rectus femoris and vastus medialis ( P < .005), and the largest gains in paretic leg power (+74% for ECC contractions, P < .0001). ECC also had greater cross-education of increased power to the untrained nonparetic leg (12%-14%, P = .006). Over the course of gait training, much of the gain in paretic leg activation in the ECC group was lost, such that the net change in agonist activation was comparable between the CON and ECC groups when the full intervention was completed. Nevertheless, improvement in walking speed postintervention was more prevalent in the ECC than CON group. Conclusion. ECC resistance training was more effective for improving bilateral neuromuscular activation, strength, and walking speed following stroke. Future research should assess whether a longer duration ECC training program can provide further benefit.

Rehabilitation of walking after stroke

OPINION STATEMENT

Rehabilitation of walking after stroke has been investigated with a variety of interventions, which will be outlined in this review. To date, the majority of interventions have demonstrated a positive, but similar effect in the primary clinical outcome of self-selected walking speed. Consistent among the most successful interventions is a focus on the intensity of the intervention and the ability to progress rehabilitation in a structured fashion. Successful progression of rehabilitation of walking likely lies in the ability to combine interventions based on an understanding of contributing underlying deficits (eg, motor control, strength, cardiovascular endurance, and dynamic balance). Rehabilitation programs must account for the need to train dynamic balance for falls prevention. Lastly, clinicians and researchers need to measure the effects of rehabilitation on participation and health related quality of life.