Christine Detrembleur

Energy cost, mechanical work, and efficiency of hemiparetic walking

The energy cost of walking (C) in nine chronic hemiparetic patients was calculated by measuring the total mechanical work (Wtot) done by the muscles and the efficiency of this work production (eta). The energy cost was twice normal in slow walkers and 1.3 times greater in fast walkers. The increase in C was proportional to the increase in Wtot and eta was normal at around 20%, despite an increase in muscle tone and muscle co-contractions. This type of approach gives a greater understanding into how segmental impairments increase Wtot and C and contribute to a patients disability.

Effect of speed on kinematic, kinetic, electromyographic and energetic reference values during treadmill walking.

OBJECTIVE Evaluation of normal and pathological gait on the level ground has drawbacks that could be overcome by walking on a treadmill. The present work was designed to assess the feasibility of extended gait analysis on a treadmill allowing multiple steps recording at a constant speed in young healthy subjects. It also aimed to provide speed-specific kinematic, kinetic, electromyographic and energetic reference values. METHOD Twelve healthy volunteers (23 +/- two years) walked on a force measuring treadmill at six speeds (1-6 k mh(-1)). Kinematics and kinetics were analysed at the hip, knee and ankle. Electromyographic muscle activity timing of quadriceps femoris, biceps femoris, tibialis anterior and lateral gastrocnemius was recorded. The energy cost was computed from oxygen consumption measurement. RESULTS All variables were speed-dependent. Kinematics and kinetics peaks amplitude increased and occurred earlier during the walking cycle with increasing walking speed. Muscle activity timing also changed with speed, although the number of bursts remained constant. The energetic cost presented a U-shaped curve, with minimal values around 4 km h(-1). Data were compared to overground walking data obtained by several authors: all results, except kinetic ones, were similar, turning down the thought that biomechanics of treadmill and overground walking could be different. CONCLUSION This study provides reference values for normal and pathological walking on treadmill and allows speed-dependent comparison between subjects.

The up and down bobbing of human walking: a compromise between muscle work and efficiency

Human walking has a peculiar straight‐legged style. Consequently, the bodys centre of mass (CM) moves up and down with each step, which is noticeable in their up and down head bobbing while walking. This vertical CM movement enables humans to save energy via a pendulum‐like mechanism but is probably a relatively recent locomotor innovation insofar as earliest bipeds may have walked flexed and flat. We investigated the mechanics, energetics, muscle efficiency and optimization of human walking by decreasing and increasing the vertical CM displacement (flat and bouncy walking) in comparison to normal walking at six speeds (1–6 km h−1). In both flat and bouncy walking, the pendular mechanism was reduced and the energy cost was increased. However, this increase was unexpectedly much sharper in flat walking where muscles provided normal mechanical work but with a decrease in muscle efficiency. In bouncy walking, muscles provided extra mechanical work in an efficient way. Our results showed that not only do humans bob up and down in normal walking to save energy via a pendulum‐like mechanism but also to make their muscles work efficiently. Actually, walking flat makes the muscles work in unfavourable conditions that waste energy. Furthermore, we are still close to a flat CM displacement relative to our current ability to change this displacement, which suggests that reducing vertical CM displacement is indeed important but only to certain limits. Evolution may ultimately have chosen the best compromise between flat locomotion that requires little work to move and bouncy locomotion that improves muscle efficiency to minimize energy consumption.

Botulinum toxin and short-term electrical stimulation in the treatment of equinus in cerebral palsy.

Intramuscular botulinum toxin type A (BT-A) has been shown to reduce spasticity and to improve gait in children with cerebral palsy. To determine whether the efficacy of BT-A may be enhanced by electrical stimulation, as suggested in focal dystonia or in adult spastic patients, 12 children with dynamic foot equinus deformity were randomly assigned to two groups in a blinded, clinically controlled trial. Intramuscular BT-A into calf muscles was followed by adjuvant electrical stimulation in Group A (n = 6) but not in Group B (n = 6). Clinical assessment and instrumented gait analysis were performed before and 1, 3, and 6 months after treatment. The combined treatment of BT-A and electrical stimulation was not superior to BT-A alone. For all patients, improvement of the clinical and gait variables occurred at 1 and 3 months after BT-A injection.Intramuscular botulinum toxin type A (BT‐A) has been shown to reduce spasticity and to improve gait in children with cerebral palsy. To determine whether the efficacy of BT‐A may be enhanced by electrical stimulation, as suggested in focal dystonia or in adult spastic patients, 12 children with dynamic foot equinus deformity were randomly assigned to two groups in a blinded, clinically controlled trial. Intramuscular BT‐A into calf muscles was followed by adjuvant electrical stimulation in Group A (n = 6) but not in Group B (n = 6). Clinical assessment and instrumented gait analysis were performed before and 1, 3, and 6 months after treatment. The combined treatment of BT‐A and electrical stimulation was not superior to BT‐A alone. For all patients, improvement of the clinical and gait variables occurred at 1 and 3 months after BT‐A injection.

Effect of Botulinum Toxin Injection in the Rectus Femoris on Stiff-Knee Gait in People With Stroke: A Prospective Observational Study

OBJECTIVE To study the effect of botulinum toxin type A (BTX-A) injection in the rectus femoris on the decreased knee flexion during the swing phase of gait (stiff-knee gait) in people with stroke. DESIGN Intervention study (before-after trial) with an observational design. SETTING Outpatient rehabilitation clinic and gait laboratory. PARTICIPANTS Nineteen chronic hemiparetic adults presenting with stiff-knee gait. INTERVENTION Injection of 200 U of BTX-A (Botox) into the rectus femoris. MAIN OUTCOME MEASURES Before and 2 months after BTX-A rectus femoris injection: Stroke Impairment Assessment Set (SIAS), Duncan-Ely test, and an instrumented gait analysis. RESULTS Median SIAS score improved from 53 (range, 36-65) to 57 (range, 42-70) (signed-rank test, P=.005) and the Duncan-Ely score from 3 (range, 1-3) to 1 (range, 0-3) (P<.001). In gait analysis, mean (+/- standard deviation) maximum knee flexion improved from 26 degrees +/-13 degrees to 31 degrees +/-14 degrees during the swing phase (paired t test, P<.001), knee flexion speed at toe-off improved from 82 degrees +/-63 degrees to 112 degrees +/-75 degrees/s (P=.009), and knee negative joint power (eccentric muscular contraction) improved from -.27+/-.23 to -.37+/-.26 W/kg (P<.001). The 4 patients who almost did not flex the knee (<10 degrees) before the BTX-A rectus femoris injection did not improve after the injection. The other 14 patients who flexed the knee more than 10 degrees before the BTX-A rectus femoris injection decreased the walking energy cost from 5.4+/-1.6 to 4.6+/-1.3 J x kg(-1) x m(-1) (P=.006). CONCLUSIONS BTX-A rectus femoris injection may be beneficial in patients with a stiff-knee gait after stroke, particularly in patients with some knee flexion (>10 degrees).

Motion of the body centre of gravity as a summary indicator of the mechanics of human pathological gait

Abnormal movements of the body segments due to lowest level gait disorders such as musculoskeletal disorders, peripheral neuropathies and radiculopathies or middle-level disorders such as hemiplegia, paraplegia and dystonia influence the motion of the centre of gravity (CG) during walking. The translation of the CG can be studied by the work done by muscles (WExt) with respect to the ground. The efficacy of gaits mechanism can be quantified by the energy transferred between gravitational potential and kinetic energies (recovery). WExt and recovery were investigated in lowest and middle-level gait disorders during level walking. No statistical significant difference was observed between patients with lowest-level gait disorders and normal subjects. However, WExt was increased for the patients with middle-level gait disorders and recovery decreased up to 20%. The measurement of changes in mechanical energy of the CG might be a summary indicator for the mechanics of pathological gait.

Mechanical work, energetic cost, and gait efficiency in children with cerebral palsy.

Abstract Many authors have reported increased energy expenditure during walking in children with hemiplegia. The origin of this increase is not well documented. The aim of our study was to understand better the origin of this increased energy expenditure of walking in children with cerebral palsy (CP) by simultaneously assessing the total mechanical work performed by the muscles and the efficiency of the work production. Twenty independently walking children with spastic, hemiplegic CP and a dynamic foot equinus deformity participated in the study. Instrumented gait analysis, including the analysis of kinematic, mechanical, and energetic variables, was performed. Despite excellent Gross Motor Function Measurement scores (range, 97-99), the energy cost was 1.3 times greater in children with CP than in healthy children. This increase in energy cost was related to an increase in the total positive mechanical work performed by the muscles and not related to a decrease in the efficiency of this work production. This study shows how segmental impairments (foot spastic equinus) increase the total mechanical work performed by the muscles and the energetic cost and how these segmental impairments contribute to the patients disability. It is useful to associate the clinical examination, classic gait analysis, mechanical work, and energetic assessment to complete the evaluation of the condition of children with CP.

Assessment of hand function in a patient with chronic sensory demyelinating neuropathy

A 60-year-old man presented with progressive large fiber sensory loss in the right first three fingers and, to a lesser extent, in both fourth and fifth fingers. Electrophysiologic studies were characteristic of chronic sensory demyelinating polyneuropathy, a variant of chronic inflammatory demyelinating polyneuropathy. Plasma exchange was unsuccessful, but intravenous immunoglobulin (IVIG) led to complete recovery of sensation for 2 months, although neurophysiologic abnormalities persisted. A battery of noninvasive tests to measure hand grip strength, tactile sensation at the fingertips, and motor control of prehension during precision grip revealed marked abnormalities in the right hand before IVIG. One month after IVIG, all test results had normalized, but they returned to pretreatment levels after 3 months. Functional evaluation of the hand may be a sensitive method to objectively quantify loss of and changes in cutaneous mechanoreceptor function of the fingers in large fiber sensory neuropathy.

The efficacy of manual therapy and exercise for different stages of non-specific low back pain: an update of systematic reviews

Abstract Objective: to review and update the evidence for different forms of manual therapy (MT) for patients with different stages of non-specific low back pain (LBP). Data sources: MEDLINE, Cochrane-Register-of-Controlled-Trials, PEDro, EMBASE. Method: A systematic review of MT with a literature search covering the period of January 2000 to April 2013 was conducted by two independent reviewers according to Cochrane and PRISMA guidelines. A total of 360 studies were evaluated using qualitative criteria. Two stages of LBP were categorized; combined acute–subacute and chronic. Further sub-classification was made according to MT intervention: MT1 (manipulation); MT2 (mobilization and soft-tissue-techniques); and MT3 (MT1 combined with MT2). In each sub-category, MT could be combined or not with exercise or usual medical care (UMC). Consequently, quantitative evaluation criteria were applied to 56 eligible randomized controlled trials (RCTs), and hence 23 low-risk of bias RCTs were identified for review. Only studies providing new updated information (11/23 RCTs) are presented here. Results: Acute–subacute LBP: STRONG-evidence in favour of MT1 when compared to sham for pain, function and health improvements in the short-term (1–3 months). MODERATE-evidence to support MT1 and MT3 combined with UMC in comparison to UMC alone for pain, function and health improvements in the short-term. Chronic LBP: MODERATE to STRONG-evidence in favour of MT1 in comparison to sham for pain, function and overall-health in the short-term. MODERATE-evidence in favour of MT3 combined with exercise or UMC in comparison to exercise and back-school was established for pain, function and quality-of-life in the short and long-term. LIMITED-evidence in favour of MT2 combined with exercise and UMC in comparison to UMC alone for pain and function from short to long-term. LIMITED-evidence of no effect for MT1 with extension-exercise compared to extension-exercise alone for pain in the short to long-term. Conclusion: This systematic review updates the evidence for MT with exercise or UMC for different stages of LBP and provides recommendations for future studies.

Quantitative assessment of intrathecally administered baclofen in spasticity.

OBJECTIVE To quantitatively assess the antispastic effect of intrathecally administered baclofen on muscle stiffness in spastic patients. DESIGN Case-control study. SETTING Clinical laboratory in a university hospital of a city of more than 1,000,000 inhabitants. PARTICIPANTS Eighteen healthy adult volunteers (9 men, 9 women) were recruited for establishing the normal values. Eleven spastic patients (8 men, 3 women) comprised the study group. MAIN OUTCOME MEASURES The resistance to passive sinusoidal displacement of 5 degrees imposed to the ankle joint was measured at frequencies from 3 to 12 Hz. Torque and displacement signals were subjected to a Fourier analysis to isolate the elastic and viscous components of the total muscle stiffness. RESULTS In comparison with the period before intrathecal injection, and with the control group, it was shown that at 4 hours after injection, stretch reflex activity was abolished and elastic and viscous muscle stiffness approached control values. The abnormal residual stiffness concerned only the elastic component due to chronic transformations of the spastic muscle and/or due to changes in joints and periarticular connective tissue. This antispastic effect was completely reversed 36 hours after injection. CONCLUSION The present study shows that the antispastic effect of intrathecally administered baclofen in spastic patients can be quantitatively assessed by a sensitive method allowing measurement of elastic and viscous components of muscle stiffness.