The stroke rate influences performance, technique and core stability during rowing ergometer.

The aim of this study is to determine the effect of stroke rate on performance, technique and core stability during rowing ergometer. Twenty-four high-level rowers performed maximal intensity one-minute bouts at 20, 28 and 34 spm on a RowPerfect3 ergometer. Power at the handle, legs, trunk and arms levels were determined, and core kinematics and neuromuscular activations were measured. The power at the handle was enhanced with a higher stroke rate in the first half of the drive phase due to higher segment's powers. This resulted in technical changes, as for instance greater mean to peak power ratio at each segment level. The higher trunk power preceded a delayed trunk extension but without significant increase in the erector spinae activation. This underlines the role of the core stability to transfer forces at a higher stroke rate. However, no co-activation parameters between trunk flexors and extensors helped further to understand this force transfer. Rowing at low stroke rate can be a training strategy to work on earlier trunk extension, while maintaining erectors spinae levels of activation. Training at higher stroke rate will induce a rowing technique closer to competition with greater neuromuscular activations, and maximise power production.

Stand-to-Sit Kinematics of the Pelvis Is Not Always as Expected: Hip and Spine Pathologies Can Have an Impact.

BACKGROUND: Stand-to-sit pelvis kinematics is commonly considered as a rotation around the bicoxofemoral axis. However, abnormal kinematics could occur for patients with musculoskeletal disorders, affecting the hip-spine complex. The aim of this study is to perform a quantitative analysis of the stand-to-sit pelvis kinematics using 3D reconstruction from biplanar x-rays. METHODS: Thirty volunteers as a control group (C), 30 patients with hip pathology (Hip), and 30 patients with spine pathology (Spine) were evaluated. All subjects underwent standing and sitting full-body biplanar x-rays. Three-dimensional reconstruction was performed in each configuration and then translated such as the middle of the line joining the center of each acetabulum corresponds to the origin. Rigid registration quantified the finite helical axis (FHA) describing the transition between standing and sitting with two specific parameters. The orientation angle (OA) is the signed 3D angle between FHA and bicoxofemoral axis, and the rotation angle (RA) represents the signed angle around FHA. RESULTS: The mean OA was -1.8° for the C group, 0.3° for Hip group, and -2.4° for Spine group. There was no significant difference in mean OA between groups. However, variability was higher for the Spine group with a standard deviation (SD) of 15.9° compared with 10.8° in the C group and 12.3° in the Hip group. The mean RA in the C group was 18.1° (SD, 9.0°). There was significant difference in RA between the Hip and Spine groups (21.1° [SD, 8.0°] and 16.4° [SD, 10.8°], respectively) (P = .04). CONCLUSION: Hip and spine pathologies affect stand-to-sit pelvic kinematics.

Robot-assisted gait training improves the pelvis control and walking function of hemiplegic stroke survivors / 中华物理医学与康复杂志

Objective To explore the effect of robot-assisted gait training on pelvis kinematics and the walking function of hemiplegic stroke survivors.Methods Thirty stroke survivors with hemiplegia were randomly divided into a treatment group and a control group,each of 15.Both groups were given routine clinical medication and rehabilitation training,while the treatment group was additionally provided with 20 minutes of robot-assisted gait training a day,6 d/wk for 8 weeks.Before and after the treatment,all of the patients' pelvis kinematics were assessed using 10 m walking speed (MWS),the timed up and go test (TUGT) and functional ambulation categorization (FAC).Results Before the treatment there were no significant differences between the two group in any of the measurements.After the treatment,significant improvement was observed in both groups in the vertical displacement and rotation and tilt angles of the pelvis while walking,with significantly more improvement in the treatment group than in the control group.There was also significant improvement in the average walking speed,TUGT time and FAC score of both groups,with significantly more improvement in the treatment group.Conclusion Robot-assisted gait training can significantly improve the pelvis control and walking ability of hemiplegic stroke survivors.

Frontal plane pelvis and hip kinematics of transfemoral amputee gait. Effect of a prosthetic foot with active ankle dorsiflexion and individualized training - a case study.

Following a transfemoral amputation (TFA), numerous changes in movement patterns during gait can occur. Frontal plane hip and pelvis compensatory strategies are recognized among individuals with a TFA, some thought to aid in safe foot clearance during the swing phase of gait. The aim of this case study was to evaluate the effect of an active ankle dorsiflexion provided by a microprocessor-controlled prosthetic foot, as well as the effect of individualized training on these parameters. In this case study, a 42-year-old male underwent 3 D gait analysis. Data were captured for two conditions; with a microprocessor-controlled prosthetic foot with active/inactive ankle dorsiflexion, during two sessions; before and after 6 weeks of individualized training. The main outcomes analyzed were frontal plane pelvis and hip kinematics. Prior to training, pelvic lift decreased slightly, coupled with an increase in hip abduction, during gait with the active ankle dorsiflexion of a prosthetic foot, compared to inactive dorsiflexion. After the training period, the pelvic lift was further decreased and an increase in hip adduction was concurrently seen. The results of this case study indicate a positive effect of the active dorsiflexion of the prosthetic foot but highlight the need for specific training after prescription of a microprocessor prosthetic foot. Implications for rehabilitation Decreased compensatory changes seen in this case study indicate a positive effect of the active dorsiflexion of the prosthetic foot, especially after a 6-week training period. Individualized training should be aimed at helping the user utilizing the benefits of the active dorsiflexion of the microprocessor prosthetic foot, implementing exercises that improve gait quality, technical training for this specific foot, strength training and balance exercises.

Human pelvis motions when walking and when riding a therapeutic horse.

A prevailing rationale for equine assisted therapies is that the motion of a horse can provide sensory stimulus and movement patterns that mimic those of natural human activities such as walking. The purpose of this study was to quantitatively measure and compare human pelvis motions when walking to those when riding a horse. Six able-bodied children (inexperienced riders, 8-12years old) participated in over-ground trials of self-paced walking and leader-paced riding on four different horses. Five kinematic measures were extracted from three-dimensional pelvis motion data: anteroposterior, superoinferior, and mediolateral translations, list angle about the anteroposterior axis, and twist angle about the superoinferior axis. There was generally as much or more variability in motion range observed between riding on the different horses as between riding and walking. Pelvis trajectories exhibited many similar features between walking and riding, including distorted lemniscate patterns in the transverse and frontal planes. In the sagittal plane the pelvis trajectory during walking exhibited a somewhat circular pattern whereas during riding it exhibited a more diagonal pattern. This study shows that riding on a horse can generate movement patterns in the human pelvis that emulate many, but not all, characteristics of those during natural walking.