جستجوی مقالات مرتبط با کلیدواژه "impulse" در نشریات گروه "پزشکی"

This study aimed to compare the effects of the Arch-Support insole on the values of Impulse, Vertical Loading Rate, and Free-Moment among handball players with the pronated foot during the jump and landing three-step shot technique.

This study was quasi-experimental and laboratory. 10 pronated foot and 10 healthy (control group) handball male players were selected as convenience sampling. The test was performed as a pre-test and post-test in two conditions with and without the use of Arch-Support insoles during the jump and landing. Two-way ANOVA test was used for statistical analysis at the significant level (P<0/05).

The inter-group results showed that the vertical loading rate (P=0.032), impulse (P<0.001), and maximum free moment (P=0.013) in two groups, control, and pronated foot during jumping; Also, the vertical loading rate (P=0.001), impulse (P<0.001), and maximum free-moment (P=0.049) in two groups, control, and pronated foot during landing had significant differences. The results of the intra-group test showed that the vertical loading rate (P < 0.001), impulse (P = 0.002), and maximum free-moment (P = 0.027) during jumping; Also, the vertical loading rate (P<0.001), impulse (P=0.001), and maximum free-moment (P=0.043) during landing in the pronated foot group had a significant decrease in the post-test compared to the pre-test.

The use of Arch-Support insoles can prevent possible injuries to the lower limbs by reducing the values of Impulse, Vertical Loading Rate, and Free-Moment.

Since changes in body alignment cause an impairment of motor skills, the purpose of this study was to investigate the effect of genu varum on the kinetics of running in anticipated and unanticipated conditions.30 elite male soccer players (two groups of genu varum and normal) were recruited in this semi-experimental study. The data of ground reaction force was collected by two force plates during running.The results showed that vertical ground reaction force and loading rate were significantly greater in genu varum group compared with normal group in both anticipated and unanticipated conditions (p≤0.05). Also, time to peak of vertical ground reaction force in unanticipated condition was longer than anticipated condition (p≤0.05). There was no significant different between groups and conditions in anterior-posterior and medial-lateral GRF, time to peak of anterior-posterior GRF, vertical and propulsive impulse and contact time (p>0.05).According to the results, it seems that kinetics of running of soccer players can be affected by genu varum and anticipation.

The aim of this study was to investigate the effects of backward gait training protocol on knee adduction moment and impulse in male patients with medial knee osteoarthritis.

This quasi-experimental study with a pretest-posttest design included two control groups (healthy and patient) and an experimental group (subjects with medial knee osteoarthritis). The subjects were 21 healthy men and 42 male patients with knee osteoarthritis who were divided into experimental and control groups according to the Kellgren and Lawrence radiologic scale and visual analogue scale. The experimental group performed backward gait training for six weeks. The dependent variables included 1st peak knee adduction moment, normalized 1st peak KAM, 2nd peak knee adduction moment and normalized 2nd peak KAM. A Vicon (130 Hz) motion analysis system with four T-Series cameras and two Kistler force plates (1000Hz) were used for data registration. Using Vicon Nexus 1.8.5 and polygon 4.1.2 softwares, data analysis was performed by paired sample t-test and one-way ANOVA (p<0.05).

Before and after training, we found no significant differences between the patients with osteoarthritis and healthy subjects in regard to peak knee adduction moment (P>0.05). However, before training significant differences were observe in knee adduction moment impulse between the healthy subjects and patients (P=0.014, P=0.004). After exercise we found decreased mean value for normalized knee adduction moment impulse in the experimental group compared to that in the healthy control group (p=0.067).

Knee adduction moment impulse can be regarded as a predictive index with high sensitivity for evaluation of the severity of knee OA. Implementation of backward gait training protocol led to decreased knee adduction moment impulse in the experimental group.

Genu varum is one of the lower limb malalignments that is associated with changes in the lower limb biomechanics during walking and running. The selected corrective program has the least complications for children. Therefore the purpose of the present study was to investigate the effects of a period of corrective exercise training program on the running ground reaction forces in children with genu varum. In this clinical trial, 17 children with genu varum from Hamadan city were volunteered to participate in 2016. Tests were done in the form of pre and post-tests. Corrective exercises were performed on subjects over a 16-week period. Paired sample t-test was used for statistical analysis of data. In the dominant limb, the peak vertical ground reaction force during push-off phase demonstrated a significant increase during the post-test compared to the pre-test (p=0.012). In the non-dominant limb, the findings showed that impulse decreased significantly in the anterior-posterior direction during the post-test compared to the pre-test (p=0.039). Also, at the non-dominant limb in the free moment, the negative peak showed a significant increase after the training period (p= 0.015). Other components such as vertical loading rate, impulse and free moment at the positive and negative peak showed no significant difference between the pre and post-test (p> 0.05). The findings indicated that the corrective exercises used in the present study improved peak ground reaction forces, impulse and free moment values, but did not have any significant effect on the loading rate.

The amount and distribution of ground reaction force during landing are linked with risk factor of the injuries related to lower limb joints. Insole may alter the amount of these forces. The objectives of this study were to analyze the effects of insole on GRF and their time-to peak of each reaction force, impulse, and loading rate during landing in normal individuals.
Thirteen healthy male subjects with mean age, mass and height of (21.9±1.6 years), (67.1±12.6 kg), and (175.3±4.9 cm), respectively, participated in this study. Using a Kistler force plates (1000Hz), GRF during landing with and without shoe insole were measured. Then, maximum GRF and their related time-to-peak, impulse and loading rate were obtained. Repeated measure ANOVA was used to analyze the data (α=0.05).
Wearing insole decreased the peak vertical GRF on heel contact of body weight (P=0.006), the loading rate (P=0.01), and the vertical impulse (P=0.0032).
Reduction of the vertical GRF and loading rate by means of insole may reduce the risk of lower extremity injuries due to impulse during landing.

Aims and The purpose of this study was to compare the parameters of ground reaction force during landing in patients with chronic low back pain. Material and 21 healthy men and 21 men with chronic low back pain participated in this study. Using a Kistler force plate )1000Hz) GRF during landing was measured. Then, maximum GRF and their related time-to-peak, impulse and loading rate were obtained. Independent t student was used to analyze the data (α=0.05). Findings: People with chronic low back pain have lower internal-external GRF and have a lower vertical GRF to touching the ground )FZ2) when landing compared to healthy people. Patients with chronic low back pain have a lower loading rate(Y)(P=.049). People with low back pain have a higher vertical ground reaction force than healthy people, and these factors are considered as a risk factor for increasing compressive forces to the spine.

In deformed spine of adolescent patients with idiopathic scoliosis, the interaction between the deformity and kinetic aspects during gait has not been well understood. The aim of this study was to analyze the ground reaction force (GRF) during gait in adolescent idiopathic scoliosis (AIS) and healthy control group.
Nineteen adolescent female patients with right thoracic idiopathic scoliosis of between 11-16 years of ages as well as 18 healthy females with similar age-matched, height and mass were studied.
Using two Kistler force plates (1000 Hz) and a Vicon system with 4 T series cameras (100 Hz), the GRF and kinematic aspects of subjects’ gait were simultaneously recorded. GRF forces in x (Fx), y (Fy), and z axes (Fz), together with impulse, loading rate, and the asymmetry index (AI) for all variables were evaluated. AI index was calculated with [(Right X – Left X)/ ((Right X Left X)*0.5)]*100. MANOVA was used to assess the between group differences, Also, repeated measure analysis of variance was used for within group comparisons. Significance level was set at at p In the right foot, all parameters of GRF were similar in AIS and control groups (p>0.05). In the left foot also, Fy and Fx components of GRF were similar between groups (P>0.05). However, the Fz1 parameter of the left foot in scoliosis group was significantly smaller than that of in control group (p=0.03). In the right and left feet, the impulses, loading rate and time related GRF variables were not different between two groups (p>0.05). The AI for all variables were similar in both groups (p AIS patients demonstrated reduced vertical GRF in left heel contact phase with respect to the control group. Unilateral alteration of the muscle function in the lower limb might be a possible explanation to this abnormality. Further more complex studies are needed to evaluate the origin and consequence of this observation.

Evaluation of ground reaction forces (GRF) and other kinetic factors have clinical importance. There is interaction between shoe type and insole with these factors. The objectives of this study were to assess the acuteeffects of arch support insole on GRF and their time-to peak of each reaction force, impulse, loading rate, and free moment during stance phase of gait in normal individuals.
Sixteen healthy male subjects with mean age, mass and height of 29.4±4.8 years, 77.9±12.6 kg, and 176.5±5.8 cm, respectively, participated on this study. Using two adjacent Kistler force plates (1000Hz) GRF during stance phase of walking with and without shoe insole were measured. Then, maximum GRF and their related time-to-peak, impulse, loading rate, and free moment were obtained. Repeated measure ANOVA was used to analyze the data (α=0.05).
Wearing insole caused reduction of the peak vertical GRF on heel contact by 6.9% of body weight (BW) (p=0.001) and the loading rate (8.4%, p=0.02), while it increased the propulsive force (7% N/BW, p=0.001), anterior-posterior impulse by 1.2% BW.s (p=0.003) and normal impulse by 2% of BW.s (p=0.032).
Reduction of the vertical GRF and loading rate by means of insole may reduce the risk of lower extremity injuries due to impulse during walking. Arch supportinsole application can prevent sport injuries by reducing the reaction forces.