Influence of Hip Joint Position on Muscle Activity during Prone Hip Extension with Knee Flexion

[Purpose] This study investigated the selective activation of the gluteus maximus during a prone hip extension with knee flexion exercise, with the hip joint in different positions. [Subjects] The subjects were 21 healthy, male volunteers. [Methods] Activities of the right gluteus maximus, right hamstrings, bilateral lumbar erector spinae, and bilateral lumbar multifidus were measured using surface electromyography during a prone hip extension with knee flexion exercise. Measurements were made with the hip joint in each of 3 positions: (1) a neutral hip joint position, (2) an abduction hip joint position, and (3) an abduction with external rotation hip joint position. [Results] Gluteus maximus activity was significantly higher when the hip was in the abduction with external rotation hip joint position than when it was in the neutral hip joint and abduction hip joint positions. Gluteus maximus activity was also significantly higher in the abduction hip joint position than in the neutral hip joint position. Hamstring activity was significantly lower when the hip was in the abduction with external rotation hip joint position than when it was in the neutral hip joint and abduction hip joint positions. [Conclusion] Abduction and external rotation of the hip during prone hip extension with knee flexion exercise selectively activates the gluteus maximus.Key words: Prone hip extension with knee flexion, Hip joint position, Electromyography     

Physical Function in Hip Osteoarthritis: Relationship to Isometric Knee Extensor Steadiness

Pua Y-H, Clark RA, Bryant AL. Physical function in hip osteoarthritis: relationship to isometric knee extensor steadiness.

Objective

To evaluate, in a community hip osteoarthritis sample, the cross-sectional associations of isometric strength and steadiness of the knee extensors and their interaction with physical performance measures of physical function.

Design

Cross-sectional.

Setting

Human movement laboratory of a university.

Participants

Sixty-seven adults (27 men and 40 women; age, 61±10y) with radiographically confirmed symptomatic hip osteoarthritis.

Interventions

Not applicable.

Main Outcome Measures

Participants performed isometric knee extensor steadiness and strength testing on a dynamometer. Physical function was assessed by using the habitual timed walk test and the self- and fast-paced stair-climbing tests.

Results

In the hierarchical regression models, although there were clear main effects of knee extensor steadiness on fast-paced stair performance, greater knee steadiness predictively associated with faster stair-climbing performance particularly in individuals with high knee extensor strength. In contrast, knee extensor steadiness was not related to gait speed regardless of knee extensor strength levels.

Conclusions

In patients with hip OA, knee extensor steadiness was positively associated with stair-climbing performance, particularly in those with high levels of knee extensor strength. These findings are of importance in developing intervention strategies, but they call for further study.     

The Effects of Knee Joint and Hip Abduction Angles on the Activation of Cervical and Abdominal Muscles during Bridging Exercises

[Purpose] The purpose of this study was to examine the effects of the flexion angle of the knee joint and the abduction angle of the hip joint on the activation of the cervical region and abdominal muscles. [Subjects] A total of 42 subjects were enrolled 9 males and 33 females. [Methods] The bridging exercise in this study was one form of exercise with a knee joint flexion angle of 90°. Based on this, a bridging exercise was conducted at the postures of abduction of the lower extremities at 0, 5, 10, and 15°. [Result] The changes in the knee joint angle and the hip abduction angle exhibited statistically significant effects on the cervical erector spinae, adductor magnus, and gluteus medius muscles. The abduction angles did not result in statistically significant effects on the upper trapezium, erector spinae, external oblique, and rectus abdominis muscles. However, in relation to the knee joint angles, during the bridging exercise, statistically significant results were exhibited. [Conclusion] When patients with both cervical and back pain do a bridging exercise, widening the knee joint angle would reduce cervical and shoulder muscle activity through minimal levels of abduction, permitting trunk muscle strengthening with reduced cervical muscle activity. This method would be helpful for strengthening trunk muscles in a selective manner.Key words: Bridging exercise, Knee and hip joint angle, Muscle activation     

The Effect of Shoulder Flexion Angles on the Recruitment of Upper-extremity Muscles during Isometric Contraction

The purpose of this study was to investigate the differences in muscle activation patterns of the biceps brachii (BB) and flexor carpi radialis (FCR) muscles, while measuring the resultant force (RF) at different shoulder flexion angles. [Subjects] Thirteen healthy males (age 24.85±3.4 years, weight; 77.8±7.9 kg; height, 1.7±0.05 m) were enrolled in this study. [Methods] The resultant force was measured by a force transducer . The elbow angle remained constant and the flexion shoulder angle was changed (30°, 45°, 60°, 75° and 90°). [Results] The results of the surface EMG show the largest muscle activities occurred at a shoulder flexion of 75° for BB and 90° for FCR. The largest resultant force was measured at a shoulder flexion angle of 75°. We conclude, that when performing the biceps curl exercise using an arm curl machine, the shoulder should be flexed at 75° to maximize the focus of the exercise for the BB. [Conclusion] These results are useful from the perspective of design as they highlight the differences in the muscle activation of BB and FCR with postural change. Ultimately this knowledge can be used in the design of rehabilitation training for the shoulder as they show that posture can affect muscle activation.     

Influence of Thoracic Flexion Syndrome on Proprioception in the Thoracic Spine

[Purpose] This study was performed to determine the difference in thoracic repositioning sense in young people with and without thoracic flexion syndrome (TFS) in target positions of half extension. [Subjects] People with TFS (n = 15; 7 men and 8 women) and people without TFS (n = 15; 7 men and 8 women) were recruited from three universities. Subjects were guided into a sitting extension target posture and were asked to move from a neutral position (2 s) to an extension target position (2 s); 10 trials were performed. [Results] People with TFS showed a significantly higher thoracic repositioning error in the extension target position than people without TFS. [Conclusion] People with TFS show a higher thoracic spine repositioning error in extension than people without TFS. A rehabilitation program to treat TFS should be implemented for individuals with decreased position sense of the thoracic spine.Key words: Proprioception, Repositioning error, Thoracic flexion syndrome     

Effects of a Bridging Exercise with Hip Adduction on the EMG Activities of the Abdominal and Hip Extensor Muscles in Females

[Purpose] This study compared the activities of the abdominal and hip extensor muscles between the bridging exercise (BE) and bridging exercise with hip adduction (BEHA) positions in women using electromyography (EMG). [Subjects] We recruited 14 healthy adult females with no history of low back pain. [Methods] The subjects performed bridging exercises with and without hip adduction. The EMG activities of the rectus abdominis (RA), external oblique (EO), internal oblique (IO), and gluteus maximus (GM) muscles were recorded. [Result] The EMG activities of all muscles were significantly increased during the BEHA compared to the BE. [Conclusion] The bridging exercise with hip adduction produced greater activation of the abdominal and hip extensor muscles.Key words: Bridging exercise, EMG, Hip adduction     

Comparison of the Forward Head Angle and the Lumbar Flexion and Rotation Angles of Computer Workers Using Routine and Individually Fixed Computer Workstations

[Purpose] This study compared the forward head angle and the lumbar flexion and rotation angles of computer workers using routine and fixed computer workstations. [Subjects] Ten male workers voluntarily consented to participate in the study. [Methods] A 3-D motion analysis system was used to measure the angles of the forward head and lumbar flexion. All subjects performed computer work for 30 minutes using both types of workstation. [Results] When working at the fixed workstation, the forward head angle was less than that observed when the routine workstation was used. At the fixed workstation, the lumbar flexion and rotation angles were less than that at the routine workstation. [Conclusion] The computer workstation individually fixed for standard posture may have prevented poor sitting posture.Key words: Computer workstation, Forward head angle, Sitting posture     

Comparison of the Lumbar Flexion Angle and EMG Activity in Trunk Muscles in Individuals with and without Limited Hip Flexion Range of Motion during Visual Display Terminal Work with Cross-Legged Sitting

[Purpose] The purpose of this study was to compare the lumbar flexion angle and electromyography (EMG) measurements of trunk muscle activity in individuals with and without limited hip flexion range of motion (ROM) during visual display terminal (VDT) work with cross-legged sitting. [Subjects] The 15 participants included a control group with sufficient hip flexion ROM (n = 7) and an experimental group with limited hip flexion ROM (n = 8). [Methods] All subjects performed VDT work with cross-legged sitting. The lumbar flexion angle was measured using a three-dimensional motion capture system, and the trunk muscle activity was recorded using a surface EMG system during VDT work with cross-legged sitting. The differences in trunk flexion angle and trunk muscle activity between the two groups were analyzed using independent t-tests. [Results] The lumbar flexion angle was significantly greater in the experimental group than the control group, although trunk muscle activity did not differ between the two groups. [Conclusion] These findings suggest that limited hip flexion leads to greater lumbar flexion during cross-legged sitting.Key words: Cross-legged sitting, Electromyography, Lumbar flexion     

A Sloped Seat Wedge Can Change the Kinematics of the Lumbar Spine of Seated Workers with Limited Hip Flexion

[Purpose] The purpose of this study was to determine whether a wedge type seat decreases the lumbar flexion angle of seated workers with limited hip flexion. [Subjects] Twelve sedentary workers with limited hip flexion were recruited. [Methods] Three seat surfaces were used: a level surface, a forward-inclining wedge, and a backward-reclining wedge. The angles of lumbar flexion and pelvic tilt were measured using a three-dimensional motion analysis system. Differences in kinematic data of the subjects seated on the three seat surfaces were analyzed using repeated one-way analysis of variance. [Results] The degree of lumbar flexion decreased significantly when using the forward-inclining wedge compared with the level surface and backward-reclining wedge. [Conclusion] These findings suggest that sitting on a forward-inclining wedge may be useful for minimizing the compensatory lumbar flexion of individuals with limited hip flexion who work in a seated position.Key words: Kinematics, Limited hip flexion, Seat wedge     

How Different Modes of Child Delivery Influence Abdominal Muscle Activities in the Active Straight Leg Raise

[Purpose] The purpose of this study was to examine the activities of the abdominal muscles of women who had experienced vaginal delivery in comparison with those who had experienced Cesarean childbirth. [Subjects and Methods] A total of 14 subjects (7 vaginal delivery, 7 Cesarean section) performed an active straight leg raise to 20 cm above the ground, and we measured the activities of the internal oblique abdominal muscle, the external oblique abdominal muscle, and the rectus abdominal muscle on both sides using electromyography. The effort required to raise the leg was scored on a Likert scale. Then, the subjects conducted maximum isometric contraction for hip joint flexion with the leg raised at 20 cm, and maximum torque and abdominal muscle activities were measured using electromyography. [Results] During the active straight leg raise, abdominal muscle activities were higher in the Cesarean section subjects. The Likert scale did not show a significant difference. The activities of the abdominal muscles and the maximum torque of the hip joint flexion at maximum isometric contraction were higher in the vaginal delivery subjects. [Conclusion] The abdominal muscles of Cesarean section subjects showed greater recruitment for maintaining pelvic stability during the active straight leg raising, but were relatively weaker when powerful force was required. Therefore, we consider that more abdominal muscle training is necessary for maintaining pelvic stability of Cesarean section subjects.Key words: Modes of delivery, Abdominal muscle, Active straight leg raising     

Comparison of Abdominal Muscle Activity in Relation to Knee Angles during Abdominal Drawing-in Exercises Using Pressure Biofeedback

[Purpose] The leg angles that are the most effective for abdominal muscle activation were investigated by performing abdominal drawing-in exercises at different leg angles with a biofeedback pressure unit. [Methods] Subjects were asked to adopt a supine position, and the tip of the biofeedback pressure unit was placed under the posterior superior iliac spine. Then, the pressure was adjusted to 40 mmHg while referring to the pressure gauge connected to the biofeedback pressure unit. Subjects were instructed to increase the pressure by 10 mmHg using the drawing-in technique upon the oral instruction, “Start,” and to maintain the drawn-in state. The time during which the pressure was maintained within an error range of ±1–2mmHg was measured in seconds. [Result] During the abdominal drawing-in exercises, the activity of the rectus abdominis, the internal and external obliques, and the transverse abdominis increased as the knee joint flexion angle increased from 45° to 120°. [Conclusion] When trunk stabilization exercises are performed at the same pressure to reduce damage after the acute phase of low back pain, trunk muscle strength can be efficiently increased by increasing the knee joint angle gradually, while performing abdominal drawing-in exercises with a biofeedback pressure unit.Key words: Trunk muscles activity, Drawing-in, Biofeedback     

The Immediate Effect of Neuromuscular Joint Facilitation (NJF) Treatment on Electromechanical Reaction Times of Hip Flexion

[Purpose] The aim of this study was to investigate the change in electromechanical reaction times (EMG-RT) of hip flexion of younger persons after neuromuscular joint facilitation (NJF) treatment. [Subjects] The subjects were 39 healthy young people, who were divided into two groups: a NJF group and a proprioceptive neuromuscular facilitation (PNF) group. The NJF group consisted of 16 subjects (7 males, 9 females), and the PNF group consisted of 23 subjects (10 males, 13 females). [Methods] Participants in the NJF group received NJF treatment. We measured the EMG-RT, the premotor time (PMT) and the motor time (MT) during hip flexion movement before and after the intervention in both groups. [Results] There were no significant differences among the results of the PNF group. For the NJF group, there were significant differences in PMT and EMG-RT after NJF treatment. [Conclusion] These results suggest that there is an immediate effect of NJF intervention on electromechanical reaction times of hip flexion.Key words: Neuromuscular joint facilitation, Hip flexion, Premotor time     

Intrinsic Properties of the Knee Extensor Muscles After Subacute Stroke

Horstman AM, Gerrits KH, Beltman MJ, Koppe PA, Janssen, TW, de Haan A. Intrinsic properties of the knee extensor muscles after subacute stroke.

Objective

To characterize muscle properties of paretic lower-limb (PL) and nonparetic lower-limb (NL) knee extensors in patients with subacute stroke.

Design

Case-control study.

Setting

Rehabilitation center research laboratory.

Participants

Patients with subacute stroke (n=14) and able-bodied age-matched control subjects (n=12).

Interventions

Not applicable.

Main Outcome Measures

Half relaxation times (HRTs) and maximal rates of torque development (MRTDs) were assessed as indicators of contractile speed using both voluntary and electrically evoked contractions. Moreover, changes in torque were measured during a fatigue protocol (35 electrically evoked intermittent contractions; 1.5s on, 2s off) and recovery.

Results

No differences among groups were found for normalized MRTDs during electrically evoked contractions (P=.117). However, during voluntary contractions both PLs (53% of control, P=.022) and NL (71% of control, P<.001) had significantly lower MRTD compared with control. Both PL (134% of control, P=.001) and NL (123% of control, P=.032) had significantly higher HRTs than control, indicating muscle slowing in patients with subacute stroke. PLs fatigued more and faster than control (P=.011) and both PL and NL recovered slower (P<.001).

Conclusions

The changes in HRTs and fatigue suggest adaptations in muscle properties toward slower, more fatigable muscle shortly after stroke. The inability to make use of contractile speed because of impaired neural activation seems the most limiting factor during the initial phase of torque development in PL. Thus, besides strengthening, muscle endurance and speed should also be addressed during rehabilitation.     

Effects of Different Frequencies of Whole Body Vibration on Repositioning Error in Patients With Chronic Low Back Pain in Different Angles of Lumbar Flexion

ObjectiveThis study aimed to evaluate the effect of high and low frequency of whole body vibration (WBV) on repositioning error in 3 different angles of lumbar flexion in patients with chronic low back pain.MethodsTwenty-four participants with chronic low back pain, aged between 20 and 35 years, were included in this randomized crossover trial study. Participants were randomly assigned into 2 groups as follows: (1) low frequency/high frequency, and (2) high frequency/low frequency. Participants received high-frequency (50 Hz) and low-frequency (30 Hz) WBV in a semi-squat position for 5 minutes in 2 sessions, with 2 weeks of rest. Before and after the WBV, lumbar repositioning error in 30% and 60% of lumbar full flexion and neutral position with eyes closed when standing was evaluated using an electrogoniometer.ResultsThe repositioning error was decreased in neutral, 30%, and 60% of lumbar flexion after the low-frequency and high-frequency WBV. Post hoc testing revealed that the effect of angle was not significant in repositioning error changes between high-frequency and low-frequency WBV (P > .05). However, the effect of low-frequency WBV on the repositioning error was significantly higher compared with high-frequency WBV (P < .05).ConclusionLow-frequency WBV might induce more improvement in the accuracy of lumbopelvic repositioning compared with high-frequency WBV with the method of WBV used in this study.     

Effects of Pelvic Belt on Hip Extensor Muscle EMG Activity during Prone Hip Extension in Females with Chronic Low Back Pain

[Purpose] This study assessed the effects of a pelvic belt (PB) on the electromyography (EMG) activity of the elector spinae (ES), gluteus maximus (GM), and biceps femoris (BF) in females with chronic low back pain (CLBP) during prone hip extension (PHE). [Subjects] Twenty female with CLBP were recruited. Surface EMG data were collected from the ES, GM, and BF muscles during a PHE task. [Results] The EMG activity in the ES bilaterally, and the right GM decreased significantly when a PB was applied compared with when a PB was not applied. [Conclusion] This suggests that a PB is effective for altering the activation pattern of the hip extensor muscles in females with CLBP during PHE.Key words: Chronic low back pain, Pelvic belt, Prone hip extension     

Assessment of Knee Proprioception in the Anterior Cruciate Ligament Injury Risk Position in Healthy Subjects: A Cross-sectional Study

[Purpose] Knee joint proprioception combines sensory input from a variety of afferent receptors that encompasses the sensations of joint position and motion. Poor proprioception is one of the risk factors of anterior cruciate ligament injury. Most studies have favored testing knee joint position sense in the sagittal plane and non-weight-bearing position. One of the most common mechanisms of noncontact anterior cruciate ligament injury is dynamic knee valgus. No study has measured joint position sense in a manner relevant to the mechanism of injury. Therefore, the aim of this study was to measure knee joint position sense in the noncontact anterior cruciate ligament injury risk position and normal condition. [Subjects and Methods] Thirty healthy male athletes participated in the study. Joint position sense was evaluated by active reproduction of the anterior cruciate ligament injury risk position and normal condition. The dominant knees of subjects were tested. [Results] The results showed less accurate knee joint position sense in the noncontact anterior cruciate ligament injury risk position rather than the normal condition. [Conclusion] The poorer joint position sense in non-contact anterior cruciate ligament injury risk position compared with the normal condition may contribute to the increased incidence of anterior cruciate ligament injury.Key words: Anterior cruciate ligament, Proprioception, Injury risk position     

Relationship Between Hip Extensor Strength and Back Extensor Length in Patients With Low Back Pain: A Cross-Sectional Study

ObjectiveThe purpose of this study was to examine the relationship between hip extensor strength and back extensor length in patients with low back pain (LBP) and healthy controls.MethodsIn 266 patients with LBP and 215 matched controls, back extensor length and hip extensor strength were measured and compared in the 2 groups using an independent t test. The Pearson correlation coefficient was used to determine correlation between these 2 variables. Multivariate logistic regression was used to test the risk of sustaining LBP with having these muscle insufficiencies.ResultsA significant difference in hip extensor strength was found between patients with LBP and controls (P < .001). Back extensor length was different in healthy men compared with the patients with LBP (P < .001) but was not significant between women with and without LBP (P = .34). The results showed a significant relationship between back extensor length and hip extensor strength in men with LBP (r = 0.6, P = .01). Multivariate logistic regression revealed that having a weak hip extensor (P = .001) or shortened back extensor (P = .01) could increase the risk of LBP occurrence.ConclusionThe findings support the assumptions of the presence of muscle imbalance of hip extensor weakness and back extensor tightness in male patients with LBP and that each muscle impairment may contribute to LBP.     

Different Sagittal Angles and Moments of Lower Extremity Joints during Single-leg Jump Landing among Various Directions in Basketball and Volleyball Athletes

[Purpose] The purpose of this study was to assess the sagittal angles and moments of lower extremity joints during single-leg jump landing in various directions. [Subjects] Eighteen male athletes participated in the study. [Methods] Participants were asked to perform single-leg jump-landing tests in four directions. Angles and net joint moments of lower extremity joints in the sagittal plane were investigated during jump-landing tests from a 30-cm-high platform with a Vicon™ motion system. The data were analyzed with one-way repeated measures ANOVA. [Results] The results showed that knee joint flexion increased and hip joint flexion decreased at foot contact. In peak angle during landing, increasing ankle dorsiflexion and decreasing hip flexion were noted. In addition, an increase in ankle plantarflexor moment occurred. [Conclusion] Adjusting the dorsiflexion angle and plantarflexor moment during landing might be the dominant strategy of athletes responding to different directions of jump landing. Decreasing hip flexion during landing is associated with a stiff landing. Sport clinicians and athletes should focus on increasing knee and hip flexion angles, a soft landing technique, in diagonal and lateral directions to reduce risk of injury.Key words: Jump landing, Joint angles, Joint moments