Are the ground reaction forces altered by the curve and with the increasing sprinting velocity?

In 200- and 400-m races, 58% of the total distance to cover is in the curve. In the curve, the sprinting performance is decreased in comparison to the straight. However, the reasons for this decreased performance is not well understood. Thus, the aim of this study was to identify the kinetic parameters underpinning the sprinting performance in the curve in comparison to the straight. Nineteen experienced-to-elite curve specialists performed five sprints in the straight and in the curve (radius 41.58 m): 10, 15, 20, 30, and 40 m. The left and the right vertical, anterior-posterior, medial-lateral, and resultant ground reaction forces (respectively F V $$ {F}_{\mathrm{V}} $$ , F A - P $$ {F}_{\mathrm{A}-\mathrm{P}} $$ , F M - L $$ {F}_{\mathrm{M}-\mathrm{L}} $$ , and F TOT $$ {F}_{\mathrm{TOT}} $$ ), the associated impulses (respectively IMP V $$ {IMP}_{\mathrm{V}} $$ , IMP A - P $$ {IMP}_{\mathrm{A}-\mathrm{P}} $$ , IMP M - L $$ {IMP}_{\mathrm{M}-\mathrm{L}} $$ , and IMP TOT $$ {IMP}_{\mathrm{TOT}} $$ ) and the stance times of each side were averaged over each distance. In the curve, the time to cover the 40-m sprint was longer than in the straight (5.52 ± 0.25 vs. 5.47 ± 0.23 s, respectively). Additionally, the left and the right F A - P $$ {F}_{\mathrm{A}-\mathrm{P}} $$ and IMP A - P $$ {IMP}_{\mathrm{A}-\mathrm{P}} $$ were lower than in the straight while the left and the right F M - L $$ {F}_{\mathrm{M}-\mathrm{L}} $$ increased, meaning that the F M - L $$ {F}_{\mathrm{M}-\mathrm{L}} $$ was more medial. The left F V $$ {F}_{\mathrm{V}} $$ was also lower than in the straight while the left stance times increased to keep the left IMP V $$ {IMP}_{\mathrm{V}} $$ similar to the straight to maintain the subsequent swing time. Overall, the sprinting performance was reduced in the curve due to a reduction in the left and the right F A - P $$ {F}_{\mathrm{A}-\mathrm{P}} $$ and IMP A - P $$ {IMP}_{\mathrm{A}-\mathrm{P}} $$ , that were likely attributed to the concomitant increased F M - L $$ {F}_{\mathrm{M}-\mathrm{L}} $$ to adopt a curvilinear motion.

Does Accelerometry at the Centre of Mass Accurately Predict the Gait Energy Expenditure in Patients with Hemiparesis?

BACKGROUND: The aim of this study was to compare energy expenditure (EE) predicted by accelerometery (EEAcc) with indirect calorimetry (EEMETA) in individuals with hemiparesis. METHODS: Twenty-four participants (12 with stroke and 12 healthy controls) performed a six-minute walk test (6MWT) during which EEMETA was measured using a portable indirect calorimetry system and EEACC was calculated using Bouten's equation (1993) with data from a three-axis accelerometer positioned between L3 and L4. RESULTS: The median EEMETA was 9.85 [8.18;11.89] W·kg-1 in the stroke group and 5.0 [4.56;5.46] W·kg-1 in the control group. The median EEACC was 8.57 [7.86;11.24] W·kg-1 in the control group and 8.2 [7.05;9.56] W·kg-1 in the stroke group. The EEACC and EEMETA were not significantly correlated in either the control (p = 0.8) or the stroke groups (p = 0.06). The Bland-Altman method showed a mean difference of 1.77 ± 3.65 W·kg-1 between the EEACC and EEMETA in the stroke group and -2.08 ± 1.59 W·kg-1 in the controls. CONCLUSIONS: The accuracy of the predicted EE, based on the accelerometer and the equations proposed by Bouten et al., was low in individuals with hemiparesis and impaired gait. This combination (sensor and Bouten's equation) is not yet suitable for use as a stand-alone measure in clinical practice for the evaluation of hemiparetic patients.

Quantification of the Risk of Musculoskeletal Disorders of the Upper Limb Using Fuzzy Logic: A Study of Manual Wheelchair Propulsion.

BACKGROUND: For manual wheelchair users, overuse of the upper limbs can cause upper limb musculoskeletal disorders, which can lead to a loss of autonomy. The main objective of this study was to quantify the risk level of musculoskeletal disorders of different slope propulsions in manual wheelchair users using fuzzy logic. METHODS: In total, 17 spinal cord injury participants were recruited. Each participant completed six passages on a motorized treadmill, the inclination of which varied between (0° to 4.8°). A motion capture system associated with instrumented wheels of a wheelchair was used. Using a biomechanical model of the upper limb and the fuzzy logic method, an Articular Discomfort Index (ADI) was developed. RESULTS: We observed an increase in articular discomfort during propulsion on a slope with increasing discomfort at the shoulder, elbow and wrist, due to an increase in kinetics. There was a kinetically significant change in the kinetic global ADI (22 to 25%) and no change in the kinematic. The ADI increased from 14 to 36% during slope propulsion for each joint. CONCLUSION: The quantification of the level of discomfort helps us to highlight the situations with the most high-risk exposures and to identify the parameters responsible for this discomfort.

Effect of botulinum toxin injection on length and force of the rectus femoris and triceps surae muscles during locomotion in patients with chronic hemiparesis (FOLOTOX).

BACKGROUND: After stroke, spasticity of the rectus femoris (RF) and triceps surae (TS) muscles frequently alters the gait pattern. Knee flexion and ankle dorsiflexion in swing are often reduced, respectively called Stiff Knee Gait (SKG) and equinus. A preliminary uncontrolled study suggested that botulinum toxin type A (BTX-A) injections could improve muscle length and force generated during gait, improving inter-segmental coordination. The aim of this randomised controlled study is thus to evaluate changes in the length of the RF and TS muscles during gait 1 month after either BTX-A or placebo injection in patients with chronic stroke, SKG and spastic equinus. The secondary aims are to evaluate peak length and peak force generated during gait, as well inter-segmental coordination assessed using the continuous relative phase method initially described by Barela et al. in patients with stroke. METHODS: This is a prospective, three-centre, randomised, placebo-controlled, triple blind study over 3 months with 4 visits. Forty patients will be included. During visits V1, V3 and V4, length and force generated by RF and TS during gait will be assessed using musculoskeletal models (MSM). Muscle force will also be assessed using an isokinetic dynamometer. Inter segmental coordination will be evaluated using 3D gait analysis and functional tests will be performed. During V2, patients will receive either an injection of BTX-A in the RF and TS muscles or a placebo injection of saline solution. DISCUSSION: We expect an increase in peak length and a decrease in peak force generated by the RF and TS muscles in the BTX-A group 1 month post injection. Moreover, we expect these parameters to be more improved in the BTX-A than the Control group. This is the first study to assess these parameters in a randomised, controlled trial using instrumented methods (isokinetic evaluation and 3D gait analysis). The results should help to improve understanding of the mechanism(s) underlying improvements in inter-segmental coordination that have been found in many previous uncontrolled studies. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01821573 , First received: March 27, 2013 Last updated: September 14, 2016 Last verified: September 2016 Other Study ID Numbers: P110136 AOM11223.

Short-term effect of volume recruitment-derecruitment manoeuvre on chest-wall motion in Duchenne muscular dystrophy.

Because progressive respiratory muscle weakness leads to decreased chest-wall motion with eventual ribcage stiffening, the purpose was to compare vital capacity (VC) and contributions of chest-wall compartments before and after volume recruitment-derecruitment manoeuvres (VRDM) in Duchenne muscular dystrophy (DMD). We studied nine patients with DMD and VC lower than 30% of predicted. VRDM was performed using 15 insufflations-exsufflations of +30 to -30 cmH2O. VC and three-dimensional chest-wall motion were measured, as well as oxygen saturation, transcutaneous partial pressure of carbon dioxide and the rapid shallow breathing index (respiratory rate/tidal volume) before (baseline) and immediately and 1 hour after VRDM. VC increased significantly immediately after VRDM (108% ± 7% of baseline, p = 0.018) but returned to baseline within 1 hour, and the rapid shallow breathing index increased significantly. The non-dominant side systematically increased immediately after VRDM ( p = 0.0077), and in the six patients with abnormal breathing asymmetry (difference >10% of VC) at baseline, this asymmetry was corrected immediately and/or 1 hour after VRDM. VRDM improved VC and reduced chest-wall motion asymmetry, but this beneficial effect waned rapidly with respiratory muscle fatigue, suggesting that VRDM may need to be repeated during the day to produce lasting benefits.

Comparison of Two Methods to Compute Respiratory Volumes Using Optoelectronic Plethysmography.

Plethysmography is an indispensable component of clinical lung function testing. However, lung volume measurement in the supine position using an optoelectronic system requires the placement of reflective markers on the anterior and lateral torso surface. The conventional method computes breath-by-breath changes in the volume between the markers and the bed, which serves as the reference plane. In contrast, the surface method consists of measuring the volume delineated by the surface area of the marker network at the onset and end of inspiration. We compared these 2 methods to spirometry during spontaneous breathing in 11 healthy volunteers and in 14 patients receiving routine visits for neuromuscular disease. Bland-Altman plots showed that agreement with spirometry was better for the surface method that the conventional method. Our results open up prospects for integrating these methods in the development of new devices.

Evaluation of 3 pushrim-activated power-assisted wheelchairs in patients with spinal cord injury.

OBJECTIVE: To assess differences between manual wheelchairs and 3 pushrim-activated power-assisted wheelchairs (PAPAWs): Servomatic A and B and E-motion. DESIGN: Repeated measures. SETTING: Rehabilitation hospital. PARTICIPANTS: Volunteers with spinal cord injuries (N=52). INTERVENTIONS: Ten subjects propelled the wheelchairs on a dynamometer, 46 evaluated each wheelchair on indoor and outdoor courses, and 10 evaluated their ability to transfer themselves and their wheelchairs into and out of their car. MAIN OUTCOME MEASURES: Oxygen consumption per unit time (V˙o2) and heart rate were measured during propulsion on the dynamometer. Wheelchair efficiency on the indoor and outdoor courses was evaluated on the basis of heart rate, completion time, handrim push frequency, and patient satisfaction. RESULTS: On the dynamometer, decreases in V˙o2 and heart rate were similar with the 3 PAPAWs compared with manual wheelchairs. On the outdoor course, heart rate was significantly decreased by PAPAWs compared with manual wheelchairs and patient satisfaction was better with Servomatic devices than with the E-motion device. Indoors, the course completion time was longer with the E-motion wheelchair than with other wheelchairs in the overall population, and handrim push frequency was higher with the E-motion wheelchair than with other wheelchairs in the subgroup with T12 to L1 injuries. Car transfer ability was lower with PAPAWs than with manual wheelchairs. CONCLUSIONS: Differences exist across PAPAWs. Compared with E-motion, the 2 Servomatic PAPAWs were easier to use outdoors, and difficulty transferring into/out of the car was similarly increased with all 3 PAPAWs.

Effect of a robotic restraint gait training versus robotic conventional gait training on gait parameters in stroke patients.

Kinematic and kinetic gait parameters have never been assessed following robotic-assisted gait training in hemiparetic patients. Previous studies suggest that restraint of the non-paretic lower limb during gait training could be a useful rehabilitation approach for hemiparetic patients. The aim of this study is to compare a new Lokomat(®) asymmetrical restraint paradigm (with a negative kinematic constraint on the non-paretic limb and a positive kinematic constraint on the paretic limb) with a conventional symmetrical Lokomat(®) training in hemiparetic subjects. We hypothesized that hip and knee kinematics on paretic side would be more improved after the asymmetrical Lokomat(®) training than after the conventional training. In a prospective observational controlled study, 26 hemiparetic subjects were randomized to one of the two groups Lokomat(®) experimental gait training (LE) or Lokomat(®) conventional gait training (LC). They were assessed using 3D gait analysis before, immediately after the 20 min of gait training and following a 20-min rest period. There was a greater increase in peak knee flexion on the paretic side following LE than LC (p = 0.04), and each type of training induced different changes in vertical GRF during single-support phase on the paretic side. Several other spatiotemporal, kinematic and kinetic gait parameters were similarly improved after both types of training. Lokomat(®) restrained gait training with a negative kinematic constraint on the non-paretic limb and a positive kinematic constraint on the paretic limb appears to be an effective approach to specifically improve knee flexion in the paretic lower limb in hemiparetic patients. This study also highlights spatiotemporal, kinematic and kinetic improvements after Lokomat(®) training, in hemiparetic subjects, rarely investigated before.

Does a single gait training session performed either overground or on a treadmill induce specific short-term effects on gait parameters in patients with hemiparesis? A randomized controlled study.

BACKGROUND: Gait training for patients with hemiparesis is carried out independently overground or on a treadmill. Several studies have shown differences in hemiparetic gait parameters during overground versus treadmill walking. However, few studies have compared the effects of these 2 gait training conditions on gait parameters, and no study has compared the short-term effects of these techniques on all biomechanical gait parameters. OBJECTIVE: To determine whether a gait training session performed overground or on a treadmill induces specific short-term effects on biomechanical gait parameters in patients with hemiparesis. METHODS: Twenty-six subjects with hemiparesis were randomly assigned to a single session of either overground or treadmill gait training. The short-term effects on spatiotemporal, kinematic, and kinetic gait parameters were assessed using gait analysis before and immediately after the training and after a 20-minute rest. RESULTS: Speed, cadence, percentage of single support phase, peak knee extension, peak propulsion, and braking on the paretic side were significantly increased after the gait training session. However, there were no specific changes dependent on the type of gait training performed (overground or on a treadmill). CONCLUSION: A gait training session performed by subjects with hemiparesis overground or on a treadmill did not induce specific short-term effects on biomechanical gait parameters. The increase in gait velocity that followed a gait training session seemed to reflect specific modifications of the paretic lower limb and adaptation of the nonparetic lower limb.

Effect of repeated, on-field sprints on kinematic variables in wheelchair rugby players.

OBJECTIVE: To evaluate the influence of repeated sprints on kinematic performance and propulsion variables during the acceleration and constant peak velocity phases in wheelchair rugby players classified as defensive (LP-D) or offensive players (HP-O). DESIGN: 22 players (13 LP-D and 9 HP-O) performed 6 × 20 m repeated sprint field tests. We calculated peak wheelchair velocities, propulsion phase times, deceleration phase times, cycle times, and left-right velocity asymmetry of the best and last sprints during the acceleration and constant peak velocity phases; the rate of decline in performance variables between the best and the last sprint and a fatigue index. RESULTS: Peak velocities during the acceleration and constant peak velocity phases and mean velocity over the whole sprint were significantly higher during the best than last sprint. Peak velocities were higher during the acceleration and constant peak velocity phases for the best and last sprint for HP-O. The rate of decline in peak velocity during the constant peak velocity phase was higher for LP-D. Fatigue index and rate of decline in velocities and sprint time were higher for LP-D. CONCLUSIONS: Performance variables and the rate of decline in performance variables depended on functional capacity and wheelchair type.

Control of bipedal posture following localised muscle fatigue of the plantar-flexors and finger-flexors.

The present experiment investigated the control of bipedal posture following localised muscle fatigue of the plantar-flexors and finger-flexors. Twelve young healthy adults voluntarily participated in this study. They were asked to stand upright as still as possible with their eyes closed in two randomly ordered experimental sessions. Each session consisted of pre- and post-fatigue bipedal static postural control measurements immediately before and after a designated fatiguing protocol for plantar-flexor and finger-flexor muscles. Centre of foot pressure (CoP) displacements were recorded using a force platform. The results showed that the postural effects of localised muscle fatigue differed between the muscles targeted by the fatiguing procedures. Indeed, localised muscle fatigue of the plantar-flexors yielded increased CoP displacements, whereas localised muscle fatigue of the finger-flexors had no significant effect on the CoP displacements. In other words, fatigue localised to muscles which are involved in the performance of the postural task (plantar-flexors) degraded postural control, whereas fatigue localised to muscles which are not involved in the performance of the postural task did not. Taken together, the present findings support the recent conclusions that the effects of localised muscle fatigue on upright postural control is joint- and/or muscle-specific, and suggest that localised muscles fatigue of the plantar-flexors could mainly affect bipedal postural control via sensorimotor rather than cognitive processes.

Effect of power-assistance on upper limb biomechanical and physiological variables during a 6-minute, manual wheelchair propulsion test: a randomised, cross-over study.

PURPOSE: Use of a power-assistance wheelchair could reduce the risk of musculoskeletal disorders (MSDs), however, a comprehensive biomechanical evaluation of these systems has not been carried out. This study aimed to evaluate and compare biomechanical UL propulsion variables, and physiological exercise-related variables during the use of a wheelchair with rear drive power assist device (RD-PAD) and a standard manual wheelchair (MW). MATERIALS AND METHODS: Twenty-two adults with spinal cord injury were recruited. RD-PAD (SmartDrive system) was fitted to their own MW. An instrumented wheel was used to measure handrim forces, and gas exchange and heart rate were monitored. Participants performed repeated out and back runs for 6 min on a straight outdoor course. RESULTS: Distance covered was significantly greater with the RD-PAD (538 ± 104 m versus 470 ± 124 m). Peak mechanical effort during the propulsion phase was significantly lower with the RD-PAD (p < 0.001). Heart rate, metabolic equivalent of task (MET), tidal volume, minute volume, oxygen consumption, and peak oxygen consumption were all significantly lower with the RD-PAD (p < 0.001). CONCLUSIONS: The results showed that use of RD-PAD increased the distance covered by MW users and reduced the energy costs of propulsion. The biomechanical results indirectly suggest that RD-PAD may reduce the risk of MSD.Implications for RehabilitationUsing the SmartDrive system as propulsion assistance increases the travel autonomy.The SmartDrive system reduces the biomechanical constraints propelling the wheelchair on a slope and low slope.SmartDrive the system reduces the physiological solicitation related to the propulsion of wheelchair.

Influence of Wheelchair Type on Kinematic Parameters in Wheelchair Rugby.

Introduction: In wheelchair rugby, players use either an offensive or defensive wheelchair depending on their field position and level of impairment. Performance of wheelchair rugby players is related to several parameters, however it is currently unclear if differences in performance are related to wheelchair type or no: the effect of wheelchair type on performance variables has not been evaluated. The aim of this study was to compare offensive and defensive wheelchairs on performance variables during a straight-line sprint. Methods: Thirteen able-bodied people performed two 20 m sprint trials: one with an offensive and one with a defensive wheelchair. Data were collected using inertial measurement units fixed on the wheelchair. Peak wheelchair velocities and left-right asymmetries in peak wheel velocities were measured during the acceleration and constant peak velocity phases. Sprint time, cycle frequency, and mean and maximum velocity were calculated over the entire sprint. Results: The peak velocities of the first 2 pushes (acceleration phase) were significantly higher with the defensive than the offensive wheelchair (p < 0.04 and p < 0.02). Mean and maximum sprint velocity were significantly higher (p < 0.03 and p < 0.04, respectively) with the defensive wheelchair. Cycle frequency and asymmetry did not differ between wheelchairs. Conclusion: Performance was higher with the defensive than the offensive wheelchair, suggesting that the frequent finding that the higher performance of offensive as compared to defensive players is not related to the use of an offensive wheelchair.

Sprint performance and force application of tennis players during manual wheelchair propulsion with and without holding a tennis racket.

The objective of this exploratory research is to study the impact of holding a tennis racket while propelling a wheelchair on kinetic and temporal parameters in a field-based environment. 13 experienced wheelchair tennis players with disabilities (36.1 ± 8.2 years, 76.8 ± 15.3 kg, 174.8 ± 17.1 cm) classified between 30/8 and first series performed two 20 m sprints in a straight line, on a tennis court: one while holding a tennis racket and the second without a tennis racket. They used their own sports wheelchair. Potential participants were excluded if they had injuries or pain that impaired propulsion. Maximal total force, maximal propulsive moment, rate of rise, maximal power output, push and cycle times and maximal velocity were measured. Sprinting while holding a tennis racket increased the cycle time by 0,051 s and push time by 0,011s. Sprinting while holding a tennis racket decreased the maximal propulsive moment, maximal power output, rate of rise and maximal velocity during propulsion by 6.713 N/m, 151.108 W, 672.500 N/s and 0.429 m/s, respectively. Our results suggest that the biomechanical changes observed associated with racket propulsion are generally in a direction that would be beneficial for the risk of injury. But sprinting holding a racket seems to decrease players propulsion performance. Working on forward accelerations with a tennis racket would be a line of work for coaches.

Impact of Holding a Badminton Racket on Spatio-Temporal and Kinetic Parameters During Manual Wheelchair Propulsion.

Introduction: Para badminton entered the Paralympic world for the first time with the 2021 Paralympic Games in Tokyo. The particularity of this sport lies in the handling of the wheelchair and the racket simultaneously. To the best of our knowledge, and considering the youthfulness of this sport, it appears that no study has looked at the impact of the badminton racket on the kinetic and spatiotemporal parameters. Therefore, the aim of our study was to investigate the impact of the badminton racket on the amplitude of kinetic and spatiotemporal parameters of wheelchair propulsion, considered as propulsion effectiveness and risk of injury criteria. We hypothesized that holding a badminton racket while propelling the wheelchair modifies the kinetics and temporal parameters of the athlete's propulsion due to the difficulty to hold the handrim, therefore decreasing propulsion effectiveness and increasing risk of injury. Materials and Methods: For six 90-min sessions, 16 able-bodied individuals were introduced to badminton. No injuries hindered their propulsion. They had to propel with and without a racket held on the dominant side along a 20 m straight line at a constant velocity of 5 km/h. They all used the same sports wheelchair equipped with two instrumented wheels (SmartWheel). Results: Participants increased their maximal total force and force rate of rise but decreased their fraction of effective force with their dominant hand compared to the non-dominant hand when using a racket. In addition, they decreased their fraction of effective force, push time, cycle time, and push angle, and increased their maximal propulsive moment, maximal total force, and force rate of rise when comparing the same dominant hand with and without the racket. Discussion: Using a badminton racket modifies the athlete's force application in a way that is generally related to lower propulsion effectiveness and a higher risk for injury. Indeed, it seems that propulsion with a racket prevents from correctly grabbing the handrim.

Handrim forces during wheelies performance in able-bodied and SCI subjects.

Context: Manual wheelchair users must be able to carry out wheelies in order to tackle obstacles in the outdoor environment. To date, no studies have compared balance variables and forces exerted on the handrim during a stationary wheelie between able bodied and spinal cord injury subjects.Objectives: To compare the distribution of forces applied to the handrim and the center of pressure displacement during a stationary wheelie between able-bodied (AB) subjects and manual wheelchair users with spinal cord injury (SCI).Design: Prospective experimental study.Setting: A university hospital laboratory.Participants: 27 participants (14 AB and 13 SCI).Outcome Measure: Each participant performed 3 stationary wheelies of 60 s duration using a wheelchair equipped with an instrumented wheel. Two force platforms were used to calculate the displacement of the center of pressure (DCOP).Results: Median group DCOP amplitude in the anteroposterior axis was smaller and less variable in the AB (19.6 mm [8.1,49.6]) than the SCI (14.9 mm [7.6,141.1]) group. Forces applied to the handrim only differed significantly between the AB (6 N [-13.8,16.6]) and SCI groups (2.7 N [-12.1 21.9]) in the posteroanterior axis.Conclusions: The results showed that the participants with SCI exerted greater PA forces on the handrim, moreover, the direction of force was opposite to that of the AB group, suggesting that the SCI group used a proactive balance strategy while the AB group used a retroactive strategy. The results suggest that the direction of force applied should be considered when teaching individuals to perform wheelies.

Performance, asymmetry and biomechanical parameters in wheelchair rugby players.

The practice of the wheelchair rugby is becoming more and more worldwide. However, few biomechanical studies have focused on this sport. The aim of this study was to compare kinematic parameters of wheelchair rugby players, classified as defensive players (LP-D) versus offensive players (HP-O). Twenty-nine wheelchair rugby players (17 LP-D and 12 HP-O) performed a 20-m sprint test. The peak velocities, temporal parameters (propulsion phase time, deceleration phase time, cycle time and cycle frequencies) and asymmetries (the difference in peak velocities between the right and the left wheels) were measured at the acceleration and constant peak velocity phases of the sprint by an inertial measurement unit which was placed on each rear wheel. At the acceleration and constant peak velocity phases, peak velocities and cycle frequencies were higher in HP-O players than LP-D players. The deceleration phase times and the cycle times were higher in LP-D players than HP-O players. However, no significant difference in asymmetry was found between LP-D players and HP-O players. The HP-O players showed superior performance than the LP-D players, but they could be more exposed at risk of injury at their upper limbs than LP-D players.

Single-session training on an ascending treadmill slope: effects on gait parameters in persons with stroke. A pilot study.

OBJECTIVE: Treadmill training with an upward incline could improve gait parameters altered in persons with stroke, especially lower limb flexion. This study aimed to determine the effects of a treadmill single-session training with a 10% upward incline on biomechanical gait parameters in persons with stroke. METHODS: Fifteen persons with stroke-related hemiparesis performed a 20-min treadmill training session with a 10% ascending incline in this interventional pilot study. Spatiotemporal, kinematic and kinetic parameters were evaluated, overground, with a tridimensional optoelectronic system, before the session, immediately after and after a 20-min rest period. RESULTS: The single-session training on a treadmill with a 10% incline has significantly increased hip flexion peak on the paretic side (39.8°± 8.1 in baseline to 42.7°± 8.6 after the session, P < 0.001, large effect size) and knee flexion peak on the paretic side (39.9°± 11.6 in baseline to 43.1°± 11.7 after the session, P = 0.004, large effect size). Gait speed, other spatiotemporal gait parameters and propulsion on the paretic side were also significantly increased (P < 0.05, all large effects size). These short-term changes were maintained after the break. CONCLUSIONS: A treadmill single-session training with a 10% upward incline induces biomechanical changes in people with stroke. The environmental constraints of this training could explain these biomechanical adaptations, concerning especially paretic hip and knee flexion.

Relevance of botulinum toxin injection and nerve block of rectus femoris to kinematic and functional parameters of stiff knee gait in hemiplegic adults.

Stiff knee gait (SKG) is common in hemiplegic patients. The main focus of treatment is rectus femoris (RF) spasticity. The aims of this study were to evaluate the effect of botulinum toxin injection (BTI) in the RF muscle on peak knee flexion during swing phase and its quantitative and functional impact on gait. We also wished to evaluate the correlation between the effects of nerve block and BTI on peak knee flexion. 10 adult hemiplegic subjects (>6 months post stroke or traumatic brain injury) with SKG and inappropriate RF EMG activity during mid-swing phase were included. 3D gait analysis, clinical and functional assessments (Timed Up and Go test, 10 m walk test, 6 min walk test and the time taken to ascend and descend a flight of stairs) were performed initially, 30 min after anaesthetic block of the RF nerve and one month post BTI. After BTI, there was a significant increase in knee flexion (8 degrees average) and a tendency towards improvement in gait and functional parameters. The effect of the nerve block on peak knee flexion was significantly correlated with the effect of BTI (11 degrees average increase in peak knee flexion after nerve block). We challenge the relevance of RF nerve blocks in this population when EMG and kinematic data are available. Our results indicate that BTI is an effective treatment for SKG in adult hemiplegic subjects, with a significant increase in peak knee flexion, no reduction in hip flexion and a tendency towards functional improvements.

Muscle force strategies for poststroke hemiparetic patients during gait.

BACKGROUND AND OBJECTIVE: Individuals who survive a stroke often display considerable gait impairments that occur in part due to inadequate muscle force production. This study aimed to investigate lower limb muscle forces in poststroke patients during walking. METHODS: Kinematics, kinetics, and electromyographic (EMG) measurements were performed on nine poststroke and healthy individuals walking at natural speed in a cross-sectional study. Recorded parameters were used in an EMG-driven model to estimate the forces exerted by the muscles around the knee and ankle joints during the stance (braking and propulsion) and swing phases. RESULTS: For hemiparetic patients, in comparison to healthy controls, the paretic side exhibited (i) lower forces generated by plantar-flexors and quadriceps respectively during the braking and propulsion phases, but (ii) higher knee-flexors forces during the propulsion phase. Regarding the non-paretic side, it displayed (i) higher forces generated by knee-flexors and quadriceps (only for the propulsion phase) forces during the stance phase, and (iii) higher plantar-flexors forces during the swing phase, in comparison to controls. CONCLUSION: Reduced forces exerted by the plantar-flexors and the knee-extensors along with increased force generated by the knee-flexors on the paretic side give possible explanation for hemiparetic gait abnormalities. Increased muscle forces exerted by the non-paretic side might be a compensatory strategy to better support body weight and properly adjust the center of mass forward.