Lower Limb Muscle Groups Research Articles

Knee extensor muscles strength indicates global lower-limb strength in individuals who have suffered a stroke: A cross-sectional study

ObjectivesThis study had three aims: (1) to evaluate the relationships between the paretic knee extensor muscle strength and global lower-limb strength in individuals who had suffered a sub-acute/chronic stroke, (2) to determine whether global lower-limb strength, sex, body mass index, or age could predict knee extensor muscle strength, and 3) to investigate whether the results obtained via a Modified Sphygmomanometer Test (MST) would be similar to those obtained using a hand-held dynamometer. MethodsThis was a cross-sectional study, performed at a research laboratory, at participants’ homes, or at outpatient clinics. Forty-two individuals with a sub-acute stroke and 45 individuals with a chronic stroke participated. Maximum isometric strength of the paretic lower-limb muscles (i.e. hip, knee, and ankle flexors/extensors, hip abductors) was measured using the MST and a hand-held dynamometer. ResultsSignificant and high correlation coefficients were found between knee extensor muscle strength and global lower-limb strength as measured by the combined strength values of 6 lower limb muscle groups in individuals with sub-acute (0.81≤r≤0.88; p<0.05) and chronic (0.82≤r≤0.85; p<0.05) stroke. Step-wise multiple regression analysis revealed that only global lower-limb strength was retained in the model and accounted for 66–78% and 67–72% (p<0.001) of the variance in knee extensor muscle strength at the sub-acute and chronic phases post-stroke, respectively. The results obtained via the MST were similar to those obtained using the hand-held dynamometer. ConclusionParetic knee extensor muscles strength, assessed using a MST or a hand-held dynamometer, indicates global lower-limb strength in individuals with a sub-acute or chronic stroke.

Assessment of isometric muscle strength and rate of torque development with hand-held dynamometry: Test-retest reliability and relationship with gait velocity after stroke

Isometric rate of torque development examines how quickly force can be exerted and may resemble everyday task demands more closely than isometric strength. Rate of torque development may provide further insight into the relationship between muscle function and gait following stroke. Aims of this study were to examine the test-retest reliability of hand-held dynamometry to measure isometric rate of torque development following stroke, to examine associations between strength and rate of torque development, and to compare the relationships of strength and rate of torque development to gait velocity. Sixty-three post-stroke adults participated (60 years, 34 male). Gait velocity was assessed using the fast-paced 10 m walk test. Isometric strength and rate of torque development of seven lower-limb muscle groups were assessed with hand-held dynamometry. Intraclass correlation coefficients were calculated for reliability and Spearman’s rho correlations were calculated for associations. Regression analyses using partial F-tests were used to compare strength and rate of torque development in their relationship with gait velocity. Good to excellent reliability was shown for strength and rate of torque development (0.82–0.97). Strong associations were found between strength and rate of torque development (0.71–0.94). Despite high correlations between strength and rate of torque development, rate of torque development failed to provide significant value to regression models that already contained strength. Assessment of isometric rate of torque development with hand-held dynamometry is reliable following stroke, however isometric strength demonstrated greater relationships with gait velocity. Further research should examine the relationship between dynamic measures of muscle strength/torque and gait after stroke.

Neuromuscular changes of the aged human hamstrings.

Despite the life-long importance for posture and locomotion, neuromuscular properties of the hamstrings muscle have not been explored with adult aging. The purpose of this study was to assess and compare age-related effects on contractile function, spinal motor neuron output expressed as motor unit (MU) discharge rates in the hamstrings of 11 young (26 ± 4 yr) and 10 old (80 ± 5 yr) men. Maximal voluntary isometric contractions (MVC), stimulated contractile properties, and surface and intramuscular electromyography (EMG) from submaximal to MVC were recorded in the biceps femoris (BF) and semimembranosus-semitendinosus (SS) muscles. MVC torque was ~50% less in the old with both age groups attaining ≥93% mean voluntary activation. Evoked twitches in the old were ~50% lower in amplitude and >150% longer in duration compared with those in the young. At successive voluntary contractions of 25, 50, and 100% MVC, MU discharge rates were up to 45% lower in old, with no differences in relative submaximal surface EMG between age groups. Furthermore, the old had significantly lower MU discharge rates in the SS at all contraction intensities compared with the BF muscle. Men in their 8th to 10th decades of life demonstrate substantially lower strength and MU discharge rates in this functionally important large lower limb muscle group, with greater age-related effect on discharge rates in the medial hamstrings. These findings, compared with those in other muscles studied, highlight that the neuromuscular properties of limb muscles, and indeed within functionally similar portions of a muscle group, are not all affected equally by the aging process. NEW & NOTEWORTHY In the hamstrings, we found that both contractile function and motor unit discharge rates across the range of voluntary intensities were lower in the old. The differences in discharge rates due to age were greater in the medial hamstrings muscle group compared with the lateral hamstrings. Compared with previous studies, these results highlight that not all muscles are affected equally by aging and there may be compartmental differences within functionally similar muscles.

Physiological Profiles of French savate Athletes

This research reviews the physiological profiles of french footfighting athletes. French boxing is a french martial art that uses the hands and feet as weapons. To be succesful in international compétitions, savate athletes must achieve excellent level of fitness and physical conditions during training.Measurement of physiological parametersEach subjet performed two kinds of incremental exercice tests. Firstly, a treadmill (Jaeger LE 500; Jaeger, Germany) test was performed at 3% gradient to determine the cardiovascular status of the players during submaximal and maximal exercise. Secondly, simuled savate test was performed with specific techniques.Heart rate responses during rest, exercise and recovery sage were noted every 5 seconds using a heart rate monitor (Polar, Finland). Maximum oxygen uptake (VO max) was measured according to the standard methodology (Astrand and Rodahl, 1970). The workload was increased every 2 min until exhaustion. Expired gases were sampled breath‐by‐breath and measured from a mixing chamber using computerized breathing gas analyzer (Oxycon Champion, Germany).ParticipantsParticipants were informed of the possible hazards of the study. Each test was scheduled at a similar time of the day to minimize the effect of daytime fluctuation. Participants were advised not to engage in strenuous activities two days before an exercise test and on the day of the test. Individuals were asked to maintain their normal diet.Arterialized samples were obtained from earlobe and under ideal conditions; this provides a good approximation of arterial concentrations of lactate, and were analyzed by the enzyme method (Boehringer Mannheim, FRG). Special care has been taken to prevent contamination from sweat and to enhance rapid circulation.ResultsVO2 max are around 3,95–4,8 l/min. No significantly, aerobic capacity was noted in treadmill tests compared to boxing tests. Further, significantly higher (p &lt; 0.02) maximal heart rates and peak lactatemia were observed. So the lactatemia is lower in specific testsDiscussionThe study of physiological responses during treadmill and boxing tests may be helpful for observing cardiovascular adaptation in boxers.Heart rate and lactatemia responses during the specific test may give a better insight into the adaptation of the boxers responses as compared in laboratory conditions.This study showed VO2max values between 55–65 ml/kg/min; and it seems that aerobic fitness discriminate elite competitive levels among French boxing athletes.The higher lactatemia with a treadmill test compared to simulated boxing test indicates a lower glycolytic demand during boxing exercise conditions. Consequently, this may suggest that the type of test (boxing test) influences aerobic energy more than the glycolytic system.Aerobic capacity was reported to play a major role in the performances of French footfighting athletes. And the majority of perceived exhaustion was higher in the lower limb muscle groups in boxing test. thus motivation, psychological factors, tactical and aerobic characteristics contribute more to performance than the lactic anaerobic system.Standard and simulated tests differ considerably. As a result, coaches should create new strategies during training sessions to achieve the same effort to replicate the profile of competitive matches.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

An Optimal Method of Training the Specific Lower Limb Muscle Group Using an Exoskeletal Robot.

This paper suggests a novel method of strengthening specific muscle groups in the lower limb during a functional movement. When the foot of an user wearing an exoskeletal robot follows a given path, the contribution of each muscle group to generate the motion changes along the path of the trajectory. The efficiency of muscle training, which is defined as the ratio of the work of a specific muscle group to that of all groups, can be maximized by changing the training load along the path. Based on a musculoskeletal model, the contribution of each muscle group along the path can be calculated as a function of its position. When a specific muscle group is chosen for exercise or rehabilitation, the efficiency of training can be maximized by setting high load where its contribution is high and low load where its contribution is low. By doing so, the user can exercise longer with the same amount of energy consumption. The EXOWheel that features a lower limb exoskeleton is employed to verify the method and the hamstring muscle group is selected as the specific muscle group. Three healthy subjects participate in the experiment, and electromyogram sensors are employed to monitor the muscle power. The results indicate that the efficiency of the hamstring muscle group for a given circular foot path under the optimal training load is 46.2% compared with 32.5% with a constant load and it means the 42% higher efficiency of the specific muscle group training.

Impact of an intensive education programme of diagnostic lung and lower limb ultrasound on physiotherapist knowledge: A pilot study.

Diagnostic ultrasound of the respiratory system and peripheral muscular systems is increasingly being used by clinicians. The aim of this study was to evaluate the knowledge outcomes of a bespoke one-day curriculum for physiotherapists that incorporated lung, diaphragm and lower limb muscle diagnostic ultrasound theory and practical training in image acquisition and analysis. A one-day course comprised of three instructors and 32 participants on key diagnostic ultrasound findings of the lungs, diaphragm and lower limb musculature included didactic lectures combined with expert-led hands-on training in practical sessions. Participants undertook pre- and post-course knowledge questionnaire covering key ultrasound findings for normal lungs, pleural/pulmonary pathologies and normal and abnormal findings for the diaphragm and key lower limb muscle groups. The pre-test and post-test questionnaire and survey results were reported using parametric descriptive statistics (means SD) as the data were normally distributed. Of the 32 physiotherapists who undertook the one-day training, 25 (78%) completed the pre- and post-course questionnaires. The pre-course knowledge scores (mean percentage, SD) were 63% (21), and the post-course scores were 62% (20) after training. This novel diagnostic ultrasound course led to limited improvements of ultrasound knowledge in the specific areas of the key ultrasound findings pulmonary system and lower limb muscle anatomy. The pre-reading material and course structure may have been too burdensome for the participants. Combined lung and muscle diagnostic ultrasound course may require more than the standard one-day training for appropriate knowledge acquisition, and use of online pre-course video lectures may facilitate learning.

Chapter 10 - Aging

This chapter reviews studies that have examined age-related anatomic and functional changes in sensory, neuromuscular, and cognitive systems that impair the control of balance and gait. Specifically, we examine age-related changes in peripheral systems: lower-limb sensation, visual functions such as contrast sensitivity and depth perception, vestibular sense, strength, and power in the lower-limb muscle groups, as well as central factors including processing speed and executive functioning. Significant impairments in any one of the above systems can predispose older people to falls, with the risk of falling increasing substantially with the number of impairments present. There is increasing evidence that interventions aimed at addressing specific sensory and neuromuscular impairments can improve balance control and reduce fall risk. In particular, task-specific exercise can improve muscle strength, balance, gait and mobility and prevent falls in older people.

Spatiotemporal gait characteristics in patients with COPD during the Gait Real-time Analysis Interactive Lab-based 6-minute walk test.

Background and aimOverground gait assessment is limited by the analysis of multiple strides or both spatiotemporal gait characteristics, while fixed speed treadmill walking restricts natural gait speed variations. The Gait Real-time Analysis Interactive Lab (GRAIL)-based 6-minute walk test (6MWT) enables 3D motion analysis and self-paced treadmill walking, and could provide insight in gait alterations in patients with chronic obstructive pulmonary disease (COPD). The aim of this study is to compare spatiotemporal gait characteristics between patients with COPD and healthy elderly during the GRAIL-based 6MWT.Materials and methodsEighty COPD patients (60% male; 62±7 years; FEV1:56±19% predicted) and 38 healthy elderly (63% male; 62±6 years; FEV1:119±17% predicted) performed two GRAIL-based 6MWTs. Mean differences and coefficient of variation of spatiotemporal gait characteristics were calculated using the trial with the largest walk distance. Sub-analyses were conducted to account for walking speed differences between groups, and muscle strength and COPD severity within the patient group.ResultsCOPD patients showed increased temporal gait characteristics, decreased stride and step lengths, and increased gait variability compared to healthy elderly (p<0.01). Stride length variability remained increased in COPD after correction for walking speed (MD:0.98%, CI:0.36–1.61, p = 0.003). Reduced quadriceps strength did not translate into altered gait characteristics, while COPD severity is associated with stride time (left MD:-0.02s, CI:-0.04–0.01, p = 0.003; right MD:-0.02s, CI:-0.04–0.01, p = 0.003).DiscussionCOPD patients performed the GRAIL-based 6MWT differently compared to healthy elderly. Further research should use other variability measures to investigate gait characteristics in COPD, to assess subtle alterations in gait and to enable development of rehabilitation strategies to improve gait, and possibly balance and fall risk in COPD. Other lower limb muscle groups should be considered when investigating gait alterations in COPD.ConclusionCOPD patients have different gait characteristics compared to healthy elderly. Independent of walking speed, COPD patients demonstrate increased stride length variability during the GRAIL-based 6MWT compared to healthy elderly.

Gait deviations in children with Duchenne Muscular Dystrophy can be directly attributed to muscle weakness in two lower limb muscle groups

Gait deviations in children with Duchenne Muscular Dystrophy can be directly attributed to muscle weakness in two lower limb muscle groups

Effects of marathon running on muscle damage in lower limb muscle groups and maximal aerobic capacity in novice recreational runners

Effects of marathon running on muscle damage in lower limb muscle groups and maximal aerobic capacity in novice recreational runners

最大一歩幅や歩行動作における下肢筋群の加齢に伴う役割の変化

最大一歩幅や歩行動作における下肢筋群の加齢に伴う役割の変化

Efficacy analysis of selective posterior rhizotomy at medullary conus for treatment of double lower extremities spastic cerebral palsy

Objective To investigate the clinical efficacy of L1-S1 selective posterior rhizotomy (SPR) at the medullary conus level for the treatment of double lower extremities spastic cerebral palsy(CP). Methods A total of 109 double lower extremities spastic CP children underwent SPR at the level of medullary consul were selected in the Second Affiliated Hospital of Xinjiang Medical University from October 2010 to May 2014.The 4 groups were analyzed in terms of muscle tension and gross motor function of the lower limbs 6 months before and after operation, retrospectively.The SPSS 17.0 software was used for statistical analysis. Results Patients had different degrees of improvement in gross motor function and reduction of spasticity in all muscle groups of lower limbs after operation.Six months after the operation, the muscular tension of hip flexor, hip adductor, knee flexor and plantar flexors (modified Ashworth spastic scale score) were all improved compared with preoperation (t=16.635, 27.411, 31.362, 38.819, all P<0.01). Gross motor function of lower limbs (Gross Motor Function Measure) at 6 months after the operation was significantly improved compared with preoperation (51.97±12.92 vs 41.01±11.46), and the difference was significant(t=26.67, P<0.01). The postoperative complications: intracranial hypotension headache (5 cases, 4.59%), postoperative high fever (2 cases, 1.83%), incision fat liquefaction (2 cases, 1.83%), sensory barriers of lower limbs (1 case, 0.92%), and urine obstacles (1 case, 0.92%). Conclusions SPR at the level of medullary conus has the advantages of minimal injury, rapid recovery and little influence on the stability of the spine.In addition, the procedure can relieve the spasticity of lower limbs of the CP patients effectively. Key words: Selective posterior rhizotomy; Medullary conus; Cerebral palsy; Spasticity

Towards Upright Pedalling to drive recovery in people who cannot walk in the first weeks after stroke: movement patterns and measurement

ObjectivesTo examine whether people who are within 31days of stroke onset are able to produce controlled lower limb movement, and phasic activity in antagonistic lower limb muscle groups, during Upright Pedalling (UP). DesignObservational study. SettingAcute stroke unit within a University Hospital. ParticipantsEight adults between 3 and 30days from stroke onset, with unilateral lower limb paresis and unable to walk without assistance. Participants were considered fit to participate as assessed by a physician-led medical team and were able to take part in UP for one, one minute session. InterventionParticipants took part in one session of instrumented UP at their comfortable cadence, as part of a feasibility study investigating UP early after stroke. Outcome measuresReciprocal activation of lower limb muscles derived from muscle activity recorded with surface EMG, quantified using Jaccards Coefficient (J); smoothness of pedalling determined from standard deviations of time spent in each of eight 45° wheel position bins (“S-Ped”). Motor behavioural measures: Motricity Index, Trunk Control Test, Functional Ambulatory Categories. ResultsParticipants were all unable to walk (FAC 0) with severe to moderate lower limb paresis (Motricity Index score/100 median 48.5, IQR 32 to 65.5). Smooth pedalling was observed; some participants pedalling similarly smoothly to healthy older adults, with a variety of muscle activation patterns in the affected and unaffected legs. ConclusionThese observational data indicate that people with substantial paresis early after stroke and who cannot walk, can produce smooth movement during UP using a variety of muscle activation strategies.

Dynamic balance ability in young elite soccer players: implication of isometric strength.

Soccer requires maintaining unilateral balance when executing movement with the contralateral leg. Despite the fact that balance requires standing with maintaining isometric posture with the support leg, currently there is a lack of studies regarding the implication of isometric strength on dynamic balance's performance among young soccer players. Therefore, the aim of this study was to examine the relationship between the Y-Balance Test and 12 lower limbs isometric strength tests. Twenty-six right footed soccer players (mean±SD, age=16.2±1.6 years, height=175±4.2 cm, body mass=68.8±6.1 kg) performed a dynamic balance test (star excursion balance-test with dominant- (DL) and nondominant-legs (NDL). Furthermore, maximal isometric contraction tests of 12 lower limb muscle groups were assessed in DL and NDL. Correlations analysis reported a significant positive relationship between some of isometric strength tests (with DL and NDL) and the Y-Balance Test. Furthermore, stepwise multiple regression analysis showed that maximal isometric strength explained between 21.9% and 49.4% of the variance of the Y-Balance Test. Moreover, maximal isometric strength was dependent upon the reaching angle of the Y-Balance Test and the leg used to support body weight. This study showed a significant implication of maximal isometric strength of the lower limb and the Y-Balance Test. Moreover, the present investigation suggests the implementation of specific lower limb strengthening exercises depending on players' deficit in each reaching direction and leg. This result suggests that further studies should experiment if increasing lower limbs isometric strength could improve dynamic balance ability among young soccer players.

Safety and feasibility of a neuromuscular electrical stimulation chronaxie-based protocol in critical ill patients: A prospective observational study

PurposeThe aim of this study was to evaluate the safety and feasibility of a neuromuscular electrical stimulation (NMES) protocol based on neuromuscular excitability and applied in numerous muscle groups of critical ill patients. Materials and methodsWe performed a prospective observational study using an NMES applied daily and bilaterally into 5 muscle groups in lower limbs for 3 consecutive days. The characteristics of NMES were 90 contractions per muscle, pulse width equal to chronaxie, and a pulse frequency of 100 Hz. We assessed safety with central venous oxygen saturation, serum lactate, and creatine phosphokinase measurements. To evaluate feasibility, we recorded the time spent for the entire NMES protocol and the number of NMES sessions completed. ResultsEleven male patients finished the study. There were no significant changes observed in creatine phosphokinase from baseline up to 96 hours: 470(±270) IU/L and 455(±240) IU/L (P>.99). Central venous oxygen saturation and serum lactate had the same pattern with no significant variations (P=.23 and P=.8, respectively). The time spent during the whole procedure and the number of complete NMES sessions performed were 107±24 minutes and 84 sessions (85%), respectively. ConclusionsWe demonstrated that NMES chronaxie-based protocol is safe and feasible.

Are Children At Risk For Developmental Coordination Disorder Weak?

Muscle strength impairment in children has implications for long term health. For children at risk for developmental coordination disorder (rDCD), the literature has shown conflicting results regarding whether or not this group has strength impairment. The extent to which this lack of consensus is related to the specific muscle groups evaluated or to other factors affecting muscle strength is unknown. PURPOSE: To evaluate, in a wide variety of lower limb muscle groups, maximal isometric muscle strength differences between children identified as rDCD and typically developing children of the same sex and either the same age or body mass. METHODS: Maximal isometric muscle strength (torque) of the hip abductors, hip flexors, hip extensors, knee flexors, knee extensors and ankle dorsiflexors was evaluated in 34 children (13 girls, 6-12 years old) identified as rDCD according to standard and accepted procedures (scoring below the 16th percentile on the Movement Assessment Battery for Children-Second Edition and having no other diagnosis in the health record that could explain these test scores). Strength values for the comparison group came from a data base of 351 children with no known health conditions. The same valid and reliable hand-held dynamometry protocol was used for both groups. Children with rDCD were randomly matched with a child in the comparison group of the same sex and either the same age or body mass. A Wilcoxon signed-rank test was used to determine group differences. A p-value of <.05 was considered significant. RESULTS: For children of the same sex and age, the rDCD group showed significantly lower strength values (from 16,34% to 40,56%, p= 0.000 to 0.011) for all muscle groups evaluated except for the dorsiflexors. When children of the same sex and body mass were compared, the rDCD was significantly weaker only for the knee extensors (29,18 %, p=0.000) and the knee flexors (14,91 %, p=0.006). CONCLUSION: Children at risk for DCD have strength impairment, but the extent of the impairment depends on the muscle group being evaluated and the characteristics, in terms of age or body mass, of the comparison group. At least some of the strength impairment may be due to growth or body size factors. Longitudinal data are required to better understand the impact of sex, growth and maturation on strength development in this group.

Spinal epidural angiolipoma

A 37-year-old female patient was referred to the hospital with pelvic pain and progressive lower limb weakness of 6 months’ duration. This weakness began during the final trimester of her pregnancy and had continued after the birth of her child. There was no associated sphincter disturbance. On questioning, the patient reported experiencing some right lower extremity weakness approximately 12 months previously, for which no cause was found despite normal brain magnetic resonance imaging and cervical spine imaging. Physical examination revealed positive Babinski signs and significant reduced power of hip flexion bilaterally, with no loss of power detected in other lower limb muscle groups. A sensory level was found at the T7 and T8 levels. A 3 Tesla magnetic resonance imaging examination of the cervical and thoracic spine, with and without contrast, was performed (Figs. 1–2). This demonstrated an avidly enhancing tumor mass in the posterior epidural space, extending craniocaudally from the level of T6 to T9 for a distance of 7 cm. Enhancing epidural soft tissue was detected, extending into the left T7–T8 neural exit foramen. There was spinal cord compression, most marked at T7 and T8. The tumor mass was surgically resected. Histopathologic evaluation confirmed a spinal angiolipoma (Figs. 3–4). Spinal angiolipoma accounts for 0.04%–1.2% of all spinal axis tumors. It predominantly occurs in the mid-thoracic region. Pregnancy is an aggravating factor in some patients. Prognosis post-resection is excellent [1].

Dynamical analysis and design of active orthoses for spinal cord injured subjects by aesthetic and energetic optimization

The dynamic analysis and simulation of human gait using multibody dynamics techniques has been a major area of research in the last decades. Nevertheless, not much attention has been paid to the analysis and simulation of robotic-assisted gait. Simulation is a very powerful tool both for assisting the design stage of active rehabilitation robots and predicting the subject–orthoses cooperation and the resulting aesthetic gait. This paper presents a parameter optimization approach that allows simulating gait motion patterns in the particular case of a subject with incomplete spinal cord injury (SCI) wearing active knee–ankle–foot orthoses at both legs. The subject is modelled as a planar multibody system actuated through the main lower limb muscle groups. A muscle force-sharing problem is solved to obtain optimal muscle activation patterns. Furthermore, denervation of muscle groups caused by the SCI is parameterized to account for different injury severities. The active orthoses are modelled as external devices attached to the legs, and their dynamic and performance parameters are taken from a real prototype. Numerical results using energetic and aesthetic objective functions, and considering different SCI severities are obtained. Detailed discussions are given related to the different motion and actuation patterns both from muscles and orthoses. The proposed methodology opens new perspectives towards the prediction of human-assisted gait, which can be very helpful for the design of new rehabilitation robots.

Walking with a four wheeled walker (rollator) significantly reduces EMG lower-limb muscle activity in healthy subjects

To investigate the immediate effect of four-wheeled- walker(rollator)walking on lower-limb muscle activity and trunk-sway in healthy subjects. In this cross-sectional design electromyographic (EMG) data was collected in six lower-limb muscle groups and trunk-sway was measured as peak-to-peak angular displacement of the centre-of-mass (level L2/3) in the sagittal and frontal-planes using the SwayStar balance system. 19 subjects walked at self-selected speed firstly without a rollator then in randomised order 1. with rollator 2. with rollator with increased weight-bearing. Rollator-walking caused statistically significant reductions in EMG activity in lower-limb muscle groups and effect-sizes were medium to large. Increased weight-bearing increased the effect. Trunk-sway in the sagittal and frontal-planes showed no statistically significant difference between conditions. Rollator-walking reduces lower-limb muscle activity but trunk-sway remains unchanged as stability is likely gained through forces generated by the upper-limbs. Short-term stability is gained but the long-term effect is unclear and requires investigation.

Creatine Supplementation and Lower Limb Strength Performance: A Systematic Review and Meta-Analyses

Creatine is the most widely used supplementation to increase strength performance. However, the few meta-analyses are more than 10 years old and suffer from inclusion bias such as the absence of randomization and placebo, the diversity of the inclusion criteria (aerobic/endurance, anaerobic/strength), no evaluation on specific muscles or group of muscles, and the considerable amount of conflicting results within the last decade. The objective of this systematic review was to evaluate meta-analyzed effects of creatine supplementation on lower limb strength performance. We conducted a systematic review and meta-analyses of all randomized controlled trials comparing creatine supplementation with a placebo, with strength performance of the lower limbs measured in exercises lasting less than 3 min. The search strategy used the keywords "creatine supplementation" and "performance". Dependent variables were creatine loading, total dose, duration, the time-intervals between baseline (T0) and the end of the supplementation (T1), as well as any training during supplementation. Independent variables were age, sex, and level of physical activity at baseline. We conducted meta-analyses at T1, and on changes between T0 and T1. Each meta-analysis was stratified within lower limb muscle groups and exercise tests. We included 60 studies (646 individuals in the creatine supplementation group and 651 controls). At T1, the effect size (ES) among stratification for squat and leg press were, respectively, 0.336 (95 % CI 0.047-0.625, p = 0.023) and 0.297 (95 % CI 0.098-0.496, p = 0.003). Overall quadriceps ES was 0.266 (95 % CI 0.150-0.381, p < 0.001). Global lower limb ES was 0.235 (95 % CI 0.125-0.346, p < 0.001). Meta-analysis on changes between T0 and T1 gave similar results. The meta-regression showed no links with characteristics of population or of supplementation, demonstrating the creatine efficacy effects, independent of all listed conditions. Creatine supplementation is effective in lower limb strength performance for exercise with a duration of less than 3 min, independent of population characteristic, training protocols, and supplementary doses and duration.