Relationship Between Balance Recovery From a Forward Fall and Lower-Limb Rate of Torque Development

The authors examined the relationship between the maximum recoverable lean angle via the tether-release method with early- or late-phase rate of torque development (RTD) and maximum torque of lower-limb muscle groups in 56 young healthy adults. Maximal isometric torque and RTD at the hip, knee, and ankle were recorded. The RTD at 50-ms intervals up to 250 ms from force onset was calculated. The results of a stepwise multiple regression analysis, early RTD for hip flexion, and knee flexion were chosen as predictive variables for the maximum recoverable lean angle. The present study suggests that some of the early RTD in the lower limb muscles, but not the maximum isometric torque, can predict the maximum recoverable lean angle

Relation between abnormal synergy and gait in patients after stroke

[Background]The abnormal synergy seen in patients after stroke is considered to limit the ability of these patients. However, in the lower extremity, antigravity torque generation rather than precise movement is needed for functions such as sit-to-stand movement and gait. Therefore, the ability to generate torque may be important either as a primary movement or as an abnormal synergy. We attempted to quantify the torque generation in the lower limb, selectively and as an abnormal synergy, and its relation with gait. [Methods]Selectively generated plantar flexion torque in the ankle and plantar flexion torque secondarily generated accompanying maximal hip extension (i.e., torque generated with abnormal synergy) were measured in subjects after stroke and control subjects. In subjects after stroke, secondary torque generation while controlling hip extension torque as 25%, 50%, and 75% of the maximal hip extension was also measured. The relation of torque generation with the gait speed and timed-up-and go test (TUG) was also analyzed. [Results]In subjects after stroke, there was no difference between the amount of plantar flexion torque generated secondarily and the selectively generated torque, whereas the selective torque was significantly greater in control subjects. Pearson product?moment correlation coefficient analysis revealed that TUG speed is related to secondarily generated torque accompanying maximal hip extension but not with selectively generated torque. [Conclusion] Secondarily generated torque was found to be a factor that affects TUG speed, and the ability to generate torque even through abnormal synergy may help for gait ability in subjects after stroke

Gait asymmetry assessment for older adults by measuring circular gait speed

[Aim]The aim of the present study was to evaluate the effectiveness of the circular gait test as a method for detecting side‐to‐side straight‐line gait asymmetry in older adults. [Methods] A total of 25 healthy older adults and 20 healthy young adults participated in this study. Walking speeds, right‐ and left‐leg step lengths, and stance durations were measured during straight‐line walking using a triaxial accelerometer (G‐walk from Bertec Japan). Step length and stance duration laterality were calculated using the side‐to‐side difference (|Left – Right|) and asymmetry index (|Left − Right|mean right and left values × 100). For circular gait, the time required to walk twice around a 1‐m diameter circle for right and left rotations was measured, and the laterality was calculated using the same formula as that described for the straight‐line gait. [Results] The results showed no differences in straight‐line step length or stance duration laterality between groups. However, circular gait asymmetry was significantly higher for older participants. A significant correlation was confirmed between circular gait time and straight‐line step length for older adults (r = 0.404). [Conclusions] The present study suggested that the circular gait test had better potential to detect age‐related changes in gait laterality than straight‐line gait step length or stance duration, and it might work as a simple assessment method for detecting laterality in straight‐line walking

Kinematic characteristics of the scapula and clavicle during military press exercise and shoulder flexion.

[Background]The military press is an exercise frequently prescribed for scapular and shoulder rehabilitation. Although this exercise has previously been analyzed by electromyography, its kinematic features remain poorly understood. In this study, we aimed to clarify these features of the military press and suggest relevant clinical applications.[Methods]Sixteen healthy men participated in this study. The participants performed the military press while holding 2 kg weights, as well as shoulder flexion with and without 2 kg weights, and an electromagnetic motion capture system was used to analyze the kinematic features of the scapula, clavicle, and humerus during these exercises. The motions of the scapula and clavicle were analyzed at 10° increments of shoulder flexion from 30° to 120°.[Results]The military press involved less scapular internal rotation, greater upward rotation, and greater posterior tilt than shoulder flexion with or without weights, especially in the starting to middle range of shoulder flexion. Greater clavicular retraction and elevation were also seen during the military press.[Discussion]The movements of the scapula and clavicle during the military press differ significantly from those during shoulder flexion with and without weights. The kinematic features of the military press, which involved less scapular internal rotation, greater upward rotation, and greater posterior tilt than did shoulder flexion, may make it a useful re-education exercise (if pain allows) for patients with decreased scapular external rotation, upward rotation, and posterior tilting. The results of this study might provide a kinematic basis for the use of this widely performed shoulder exercise

Effect of balance exercise in combination with whole-body vibration on muscle activity of the stepping limb during a forward fall in older women: A randomized controlled pilot study.

This study investigated the effects of balance exercise combined with whole-body vibration (WBV) on step performance and lower limb muscle activity during simulated forward falls using the tether-release method in older women. Twenty older women were assigned to either a WBV plus balance exercise group (WBV, n=10) or a balance exercise without vibration group (standard balance exercise group [STE], n=10). WBV performed weight-bearing exercises on a WBV platform combined with other balance exercises as a home program, whereas STE performed the same exercises without WBV. The exercise volume was equal in both intervention groups (3×/week for 12 weeks×30min/session). The EMG and kinematic data of the stepping leg from the balance recovery step were examined before and after the intervention. While both groups extended step length during forward falls after the intervention, only WBV increased step velocity. EMG analysis of the balance recovery step showed that both groups increased peak EMG of knee flexor and extensor muscles after intervention. After intervention, WBV increased peak EMG of the plantar flexors, which are used to exert the push-off forces just before the leg swing. Balance exercise in older women resulted in significant improvements in the balance recovery step after a simulated forward fall. WBV also had the additional benefit of improved step velocity, which was reflected in increased activity of the plantar flexors in the stepping leg

Acute effect of electrical stimulation on the infraspinatus muscle using different types of muscle contractions and shoulder joint positions

BACKGROUND: Electrical stimulation (ES) is considered to be effective on infraspinatus muscle with functional decline and atrophy. However, it is not clear which parameters of ES e.g., types of muscle contractions and shoulder joint positions have good effects for inducing hypertrophy and increasing muscular strength. The purpose of this study was to determine the acute effects of ES in different types of muscle contractions and shoulder joint positions on the infraspinatus muscle by measuring the muscle swelling after ES. METHODS: Forty subjects were randomly assigned to one of five groups: an isometric contraction with maximum internal rotation (IR), an isometric contraction with neutral position of rotation (NEUT), an isometric contraction with maximum external rotation (ER), a concentric contraction (CONCEN), and a control (CON) group. Subjects in all groups except for the CON group received ES for 20 min. The CON group did not receive intervention. The muscle thicknesses of the superior and inferior infraspinatus were measured using ultrasonography before and immediately after a single ES intervention. RESULTS: Percentage change in muscle thickness of the inferior infraspinatus was greater in the IR and NEUT groups than the muscle thickness of the CON group; however, the muscle thickness of the superior infraspinatus did not differ significantly among the groups. CONCLUSIONS: The results of this study indicate that applying ES to the inferior infraspinatus muscle in an isometric contraction with the muscle in a stretched position is an effective method to induce greater muscle swelling

Electromyographic analysis of training to selectively strengthen the lumbar multifidus muscle: effects of different lifting directions and weight loading of the extremities during quadruped upper and lower extremity lifts

Objective: The lumbar multifidus muscle (LMF) is a lower back muscle that contributes to spinal stability. Several electromyographic analyses have evaluated LMF activity during various types of training. The present study examined the activity of the back muscles during quadruped upper and lower extremity lifts (QULELs) with different lifting direction and weight loading of extremities. Methods: Seventeen healthy men were included as subjects. The exercise conditions comprised raising the upper extremity of one side and the lower extremity of the opposite side in a quadruped position with different lifting direction and weight loading. The various combinations of lifts were modifications of conventional QULEL, in which the upper extremity is raised to 180° shoulder flexion and the lower extremity to 0° hip extension. The effects of different lifting directions and weight loading on LMF and lumbar erector spinae (LES) muscle activities were measured using surface electromyography. Results: The LMF activity and the LMF/LES activity ratio on the side of lower extremity lifting were higher during QULEL with the upper and lower extremities in abduction than during conventional QULEL. The LMF/LES activity ratio was lower during QULEL with weight loading on the upper and lower extremities than during conventional QULEL. Conclusion: The results of the present study suggest that QULEL with shoulder and hip abduction is more effective to selectively strengthen LMF on the side, where the lower extremity is lifted. Loading weight onto both the lifted upper and lower extremities during QULEL is disadvantageous as a selective LMF training method because the LMF/LES activity ratio is low

Effects of a Thermal Agent and Physical Activity on Muscle Tendon Stiffness, as Well as the Effects Combined With Static Stretching

Context: A recent review or article reported that thermal agents (TA) or physical activity (PA) can increase range of motion (ROM) and that the combination of TA with stretching is superior to performing stretching only. However, since ROM is affected by the psychological factors, it is questionable whether these studies measured the effect of these interventions on muscle flexibility. By measuring muscle stiffness, the authors attempted to evaluate the effect these interventions on muscle flexibility. Objective: To compare the individual effects of TA and PA on muscle flexibility, as well as their effectiveness when combined with static stretching (SS). Design: Crossover trial. Setting: University research laboratory. Participants: 15 healthy men without a history of orthopedic disease in their lower limbs. Interventions: 15 minutes of 3 different conditions: hot pack as TA, pedaling exercise as PA, and the control group with no TA or PA intervention, followed by 3 min of SS for the hamstrings. Main Outcome Measures: Joint angle and passive torque of the knee during passive elongation were obtained prior to interventions, after 3 kinds of intervention, and after SS. From these data, muscle-tendon-unit (MTU) stiffness of the hamstrings was calculated. Results: Although knee-joint ROM increased with both TA and PA (P < .05), there were no significant differences in MTU stiffness between pre- and postintervention measurements for either of the interventions (TA, P = .477; PA, P = .377; control, P = .388). However, there were similar significant decreases in MTU stiffness between postintervention and post-SS for all conditions (P < .01). Conclusions: TA and PA did not decrease MTU stiffness, and combining these interventions with SS did not provide additional decreases in MTU stiffness compared with performing SS alone

Isometric muscle activation of the serratus anterior and trapezius muscles varies by arm position: A pilot study with healthy volunteers with implications for rehabilitation

[Background]This study aimed to determine the most appropriate angle and moving direction of the arm for improving coordination of the periscapular muscles, including the serratus anterior (SA), upper trapezius (UT), middle trapezius (MT), and lower trapezius (LT). [Methods]Muscle activation amplitudes were evaluated in the SA, UT, MT, and LT in 11 healthy subjects by use of surface electromyography. The subjects were asked to maintain the arm position at 5 elevated positions with maximal effort against applied manual forces, which were directed from upper to lower (test 1), lower to upper (test 2), posterior to anterior in the frontal plane and lateral to medial in the sagittal plane (test 3), and anterior to posterior in the frontal plane and medial to lateral in the sagittal plane (test 4). The relative activity of the UT with respect to the SA, MT, and LT was calculated, resulting in the UT/SA, UT/MT, and UT/LT ratios. [Results]Test 4 in all positions but 150° of elevation in the frontal plane showed high activity of the SA with a low UT/SA ratio. High MT activity with a low UT/MT ratio was observed during test 3 at the 90° elevated position, whereas high LT activity without UT hyperactivation was not found. [Discussion]To strengthen the periscapular muscles in the balanced condition, horizontal adduction is recommended for the SA. Horizontal abduction at the 90° elevated position should be effective for the MT. Because no technique in this study was effective for the LT, further studies are needed

Relative mobility of the pelvis and spine during trunk axial rotation in chronic low back pain patients: A case-control study

<div><p>Background</p><p>Trunk axial rotation is a risk factor for chronic low back pain (CLBP). The characteristics of rotational mobility in the pelvis and spine among CLBP patients are not fully understood.</p><p>Purpose</p><p>The purpose of this study was to examine three-dimensional kinematic changes, and to compare the differences of rotational mobility and coupled motion, in patients with and without CLBP.</p><p>Methods</p><p>Fifteen patients with CLBP and 15 age and sex matched healthy subjects participated in this study. Each subject performed trunk rotation to maximum range of motion (ROM) in a standing position. The kinematics data was collected using a three-dimensional motion analysis system. The outcomes measured were the rotational ROM and the spine/pelvis ratio (SPR) in transvers plane at both maximum and 50% rotation position. The coupled angles in sagittal and frontal planes were also measured.</p><p>Results</p><p>No significant differences in rotational ROM of the thorax, pelvis, and spine were observed between two groups at maximum rotation position. However, there was a significant interaction between groups and rotational ROM of pelvis and spine (F = 4.57, p = 0.04), and the SPR in CLBP patients was significantly greater than that of the healthy subjects (CLBP; 0.50 ± 0.10 Control; 0.41 ± 0.12, p = 0.04). The results at 50% rotation position were similar to that at maximum rotation. This indicates a relative increase in spinal rotation in the CLBP patients during trunk rotation. Moreover, the CLBP patients exhibited a significantly higher anterior tilt of the pelvis and extension of the spine in the sagittal plane coupled with rotation.</p><p>Conclusions</p><p>CLBP patients had relative hyper rotational mobility of the spine as well as excessive spinal extension coupled with trunk rotation. These results suggest that uncoordinated trunk rotation might be a functional failure associated with CLBP.</p></div