End Range Of Motion Research Articles

Differentiation of strains in the lateral and medial bands of the iliofemoral ligament: A segmental approach.

Iliofemoral ligament strains have been assessed in a circumscribed portion, limiting the information regarding the strains in the proximal, mid and distal portions. The purpose of this study is to describe the longitudinal and transversal strain within the proximal, mid and distal portions of the lateral and medial bands of the iliofemoral ligament. Ten fresh cadaveric specimens were assessed. The iliofemoral ligaments were divided into medial and lateral bands. Hemispherical beads (2.6 mm) were placed on the lateral and medial borders of each band. Four positions were assessed: abduction, extension, internal and external rotations combined with extension. The hemispherical beads were scanned at the end range of motion using a laser scanner. The three-dimensional position of each bead was used to estimate longitudinal and transversal strains. A three-factor ANOVA was used to compare movements, borders, and portions within each ligament for longitudinal strains. A one-way ANOVA was used to compare transversal strains between portions. This technique showed mean reliability (ICC: 2, 1) of 0.90 ± 0.06. The external rotation showed the highest strains in both ligaments (p < 0.05). Abduction showed a significant difference between the lateral and medial borders in both bands (p = 0.001). Eight movement-border combinations showed a significant difference between proximal, medial, and lateral portions (p < 0.005). According to our results, there is a clear effect of portions (proximal, mid and distal) within the ligament and movements. Abduction shows the lowest strains longitudinally but the largest strains transversally. Although we do not know the impact of this phenomenon, future studies should assess the strains following hip arthroscopies. The latter might improve the impact of this procedure on hip biomechanics. Lastly, the iliofemoral ligament should be assessed using a segmental approach rather than as a complete unit.

A human surrogate neck for traumatic brain injury research.

Properties of the human neck such as range and resistance to motion are considered important determinants of the kinematic response of the head pre, during and post-impact. Mechanical surrogate necks (i.e., anthropomorphic test device necks), have generally been limited to a single anatomical plane of motion and an artificially high resistance to motion. The aim of this study was to present the Loughborough University Surrogate Neck that is representative of the 50th percentile human male neck, developed for motion in and between each of the anatomical planes with inertial and flexural stiffness properties matching those of a passive elastic (i.e., negligible active tension) neck muscle state. The complex intervertebral joints were reduced to three encapsulated ball joints with appropriate locations, orientations and distributed range of motion to precisely position and orientate the head with respect to the torso at the neutral position and end range of motion. A plain bearing sub-assembly was incorporated at the C1-C2 vertebral level to permit 50% of the axial rotation with negligible resistance to motion, as exhibited by humans. Detachable elastomeric elements provided resistance to motion across each ball joint and permit any orientation of the head within the physiological range of motion of the joints. The mass of the surrogate neck (1.62Kg) was in agreement with the typical human range and similar agreement was found for the principal moments of inertia (Ixx 26.8kgcm2, Iyy 20.5kgcm2 and Izz 14.3kgcm2). Quasi-static bending moment and dynamic torque tests characterised the surrogate neck in flexion/extension, lateral flexion and axial rotation. With respect to commercial surrogate necks, the surrogate neck presented here was in closer agreement to the reported human responses, for equivalent loading conditions. The applications of a surrogate neck that can appropriately constrain the head relative to the torso are far reaching in the areas of brain injury mechanism research, and for the development and assessment of protective equipment to reduce the risk of such injuries.

Influence of Spine-Focused Verbal Instruction on Spine Flexion During Lifting.

Lifting with a flexed spine, especially near the end range of motion, has been identified as a potential risk factor for low back injury/pain. Therefore, individuals who develop discomfort from repetitive, prolonged and/or loaded flexed or slouched postures may benefit from a greater awareness of how to control and/or modify their spinal posture to avoid irritating their backs in these situations. This study was therefore designed to test the ability of spine-oriented verbal instructions to reduce intersegmental spine flexion during three lifting tasks. The lifts were first performed without any instructions on lifting technique. An audio recording was then played with instructions to limit bending in the lower back before repeating the lifts. Following the verbal instructions, maximum spine flexion angles significantly (p < 0.05) decreased at intersegmental levels in the lower thoracic and upper lumbar (T8/T9 to L2/L3) regions, but no significant changes were observed at the lower lumbar levels (L3/L4 to L5/S1). Thus, it is concluded that spine-oriented verbal instructions can decrease spine flexion during lifting; however, other cues/instructions may be required to target lower lumbar levels which have been identified as the most prone to injury/pain.

Association between static stretching load and changes in the flexibility of the hamstrings

The purpose of the present study was to examine the association between static stretching load and changes in the flexibility of the hamstrings. Twelve healthy men received static stretching for 60 s at two different intensities based on the point of discomfort (100%POD and 120%POD intensity), in random order. To assess the flexibility of the hamstrings, the knee extension range of motion (ROM). Passive torque at end ROM, and muscle–tendon unit stiffness were measured before and after stretching. The static stretching load was calculated from the passive torque throughout static stretching. The knee extension ROM and passive torque at end ROM increased in both intensities (p < 0.01). The muscle–tendon unit stiffness decreased only in the 120%POD (p < 0.01). There were significant correlations between the static stretching load and the relative changes in the knee extension ROM (r = 0.56, p < 0.01) and muscle–tendon unit stiffness (r = − 0.76, p < 0.01). The results suggested that the static stretching load had significant effects on changes in the knee extension ROM and muscle–tendon unit stiffness of the hamstrings, and high-intensity static stretching was useful for improving the flexibility of the hamstrings because of its high static stretching load.

Time course of changes in the range of motion and muscle-tendon unit stiffness of the hamstrings after two different intensities of static stretching.

ObjectivesThe purpose of this study was to examine the time course of changes in the range of motion and muscle-tendon unit stiffness of the hamstrings after two different intensities of static stretching.MethodsFourteen healthy men (20.9 ± 0.7 years, 169.1 ± 7.5cm, 61.6 ± 6.5kg) received static stretching for 60 seconds at two different intensities based on the point of discomfort (100%POD and 120%POD) of each participant, in random order. To evaluate the time course of changes in the flexibility of the hamstrings, the knee extension range of motion (ROM), passive torque at end ROM, and muscle-tendon unit stiffness were measured pre-stretching, post-stretching, and at both 10 and 20 minutes after static stretching.ResultsFor both intensities, ROM and passive torque at pre-stretching were significantly smaller than those at post-stretching (p < 0.01 in both intensities), 10 minutes (p < 0.01 in both intensities), and 20 minutes (p < 0.01 in both intensities). The muscle-tendon unit stiffness at pre-stretching was significantly higher than that at post-stretching (p < 0.01), 10 minutes (p < 0.01), and 20 minutes (p < 0.01) only in the 120%POD, but it showed no change in the 100%POD.ConclusionThe results showed that ROM and passive torque increased in both intensities, and the effects continued for at least 20 minutes after stretching regardless of stretching intensity. However, the muscle-tendon unit stiffness of the hamstrings decreased only after static stretching at the intensity of 120%POD, and the effects continued for at least 20 minutes after stretching.

The acute effects of high-intensity jack-knife stretching on the flexibility of the hamstrings

The purpose of the present study was to examine the acute effects of high-intensity jack-knife stretching for 60 s on flexibility of the hamstrings. Twelve healthy participants underwent jack-knife stretching for 60 s (3 repetitions of 20 s stretching with 30 s intervals) at two different intensities based on the point of discomfort (POD and PODmax). To examine any change in flexibility, knee extension range of motion (ROM), passive torque at end ROM, and muscle–tendon unit stiffness were measured before and after stretching. To evaluate hamstrings pain, a numerical rating scale (NRS) was described. The knee extension ROM (p < 0.01) and passive torque at end ROM (p < 0.05) were significantly increased at both intensities. The muscle–tendon unit stiffness was significantly decreased in PODmax intensity (p < 0.01), but there was no change in POD intensity (p = 0.18). The median values of NRS during the stretching were 0 and 6–7 in POD and PODmax intensity, respectively, although it was 0 immediately after the stretching protocol in both intensities. These data suggested that high-intensity jack-knife stretching is an effective and safe method to decrease muscle–tendon unit stiffness of the hamstrings.

EFFECTS OF DRY NEEDLING ON CALF MUSCLE IN CASE OF MYOFASCIAL TRIGGER POINT WITH MILD RESTRICTION OF KNEE JOINT MOVEMENT: A CASE STUDY

Background: Trigger point on calf muscle is a common musculoskeletal condition it is usually felt as an intense pain when the concerned extremity is used to put on weight.The upper medial and upper lateral trigger points refer pain locally to the back of the knee causing slight end range restrictions. it is the most common musculoskeletal complaint presenting to physicaltherapy. Objective: Reduction of calf pain and to improve the end range of motion of the knee joint. Thus, helps in enhancing the functional activities. Methods: The study was done on one patient aiming to reduce calf pain and mild end range restriction of knee joint movements, we used dry needling technique for treatmentpurpose Result: We found reduction in the calf muscle pain and improvement in end range of movement of the knee joint after 2 sessions of dry needling. Case Representation: one patient came to us having pain on calf muscle, local tenderness and end range restriction of the knee joint and patient was having no history of trauma patient was undergoing for analgesic medication.

Immediate effect of muscle energy technique versus passive stretching for upper trapezius muscle on neck pain

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; Neck pain is a common musculoskeletal problem in the General population. Upper trapezius is a superficial postural muscle that tends to get shortened due to overuse activity which causes neck pain and reduces neck mobility. The aim of this study was to compare the immediate effect of Muscle energy technique (MET) and passive stretching of upper trapezius muscle in neck pain patients.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods:&lt;/strong&gt; An experimental study was undertaken during period from March 2017 to March 2018. 358 participants with Neck pain were included in this study. Participants were divided in two groups: Group A received Hot pack and MET for upper Trapezius. Group B received Hot pack and Passive stretching for upper trapezius. Visual analogue scale (VAS) at end range of motion (ROM), same cervical side flexion and opposite side cervical rotation by goniometer and tape were taken as outcome measures. Participants were assessed prior to the treatment, immediately after the treatment and post 24 hours to see the carry over treatment.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results: &lt;/strong&gt;Mann Whitney U test showed that VAS at end range of motion, opposite side cervical rotation and same side cervical side flexion had significant improvement in MET group as compared to passive stretching group (p&amp;lt;0.0001). Carry over effect was less significant with p&amp;lt;0.0001.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Conclusions: &lt;/strong&gt;A single session of MET for upper trapezius muscle reduced the pain intensity (VAS) and increased the cervical rotation and cervical side flexion.&lt;/p&gt;

Measuring Bone Loss in the Unstable Shoulder: Understanding and Applying the Track Concept.

An interesting international debate has been developed over the past 10 years (the last decade) surrounding the surgical procedure for recurrent anteroinferior instability and a definitive consensus is lacking on the factors which favor one technique over another, especially when bone loss is present (soft tissue vs. bone block). Glenoid bone loss is commonly observed in the shoulder with anterior instability, and it is difficult to evaluate the shape of the glenoid using plain radiograph, therefore, computed tomography or intraoperative observation is recommended for accurate assessment of glenoid bone loss and Hill-Sachs lesion. When we consider the bony defect of the glenoid as a risk factor for surgical failure, it is crucial to take into consideration the features of a concomitant Hill-Sachs lesion. However, all the previous reports focusing on the size of the Hill-Sachs lesion or on the glenoid bone loss in isolation, overlook the interaction of the 2 lesions through the arc of range of motion and how this may influence instability. The glenoid track is the first model to determine, in a dynamic way, how bone loss on both sides of the joint can lead to instability. The glenoid track is a zone of contact created by the glenoid on the humeral articular surface when the arm is moved along the end-range of motion (abduction and external rotation). The use of the glenoid track concept can potentially help guide surgical decision-making.

Pitching shoulder passive flexibility: torque-angle analysis for external rotation and internal rotation

ABSTRACT In this study, a custom device was developed to analyse the pitching shoulder’s external rotation (ER) and internal rotation (IR) passive flexibility. We analysed three novel measures: the resistance onset angle (ROA = angle where the shoulder begins stretching), rotational stiffness, and torque at the end range of motion (ROM). The purpose was to conduct a bilateral analysis to determine if there are significant differences between the throwing and non-throwing shoulder. Participants were 30 upper level pitchers (13 division I, 17 minor league). During testing, pitchers laid supine on a treatment table and the arm was secured to a rotational wheel with the shoulder abducted 90° and elbow flexed 90°. Dependent t-tests revealed significant (p < 0.01) and relatively extreme bilateral differences for all three variables. The throwing shoulder had: increased ER ROA (9°), decreased IR ROA (5.3°), increased ER stiffness (17%), increased IR stiffness (34%), increased ER torque (21%), and increased IR torque (30%). Secondary correlation analysis was completed to determine if the torque-angle variables were good predictors of the end ROM. Stiffness correlations were weak for ER (r = 0.35, p = 0.048) and IR (r = 0.42, p = 0.017) but ROA correlations were strong for ER (r = 0.85, p < 0.001) and IR (r = 0.86, p < 0.001).

All-Arthroscopic, 270° Reconstruction of the Inferior Glenohumeral Ligament With Palmaris Longus Autograft

Numerous factors play a role in anterior shoulder stability. The inferior glenohumeral ligament, especially the anterior band, is the main passive anterior stabilizer in the end range of motion. Surgical treatment of this pathology continues to be a challenge in patients with capsular deficiency, in whom the recurrence rate of soft-tissue arthroscopic repair increases significantly. There is not yet a fair solution for these patients without glenoid bone loss, in whom the poor tissue quality determines recurrent instability. We present an all-arthroscopic technique for reconstruction of the inferior glenohumeral ligament by means of palmaris longus autograft as an alternative to nonanatomic bone block procedures.

In Which Arm Position Is a Hill-Sachs Lesion Created?

Background: It has been believed that a Hill-Sachs lesion (HSL) is created with the arm in abduction and external rotation at the time of dislocation. However, no studies have clarified the arm position in which an HSL is created. Purpose: To determine the arm position in which an HSL is created. Study Design: Descriptive laboratory study. Methods: The computed tomography images of 100 shoulders of 100 patients (72 males and 28 females; mean age, 30 years old) with recurrent anterior dislocation of the shoulder were investigated using an image analyzing software. Three-dimensional surface bone models of the scapula and humerus were created separately. The humerus was moved so that the HSL perfectly fit the anterior rim of the glenoid. This arm position was recorded 3-dimensionally. Results: Considering the scapulohumeral rhythm, the average arm position in which the HSL and the anterior glenoid rim best fit was 74° of abduction, 27° of external rotation, and 3° of horizontal flexion relative to the trunk. Conclusion: The arm position when an HSL and the anterior glenoid rim best fit is 74° of abduction, 27° of external rotation, and 3° of horizontal flexion, which seems to be the arm position when the HSL has been created. This result suggests 2 possibilities: dislocation occurred in this midrange position or HSL was not created at the time of dislocation but later in the mid–range of motion. However, as we have no information on the arm position at the time of dislocation, we cannot conclude which of these possibilities is true in our study. Clinical Relevance: This study gives us a better understanding of the timing of HSL occurrence. Shoulder dislocation may occur at the end range of motion or in the mid–range of motion, but an HSL is created in the mid–range of motion.

Comparison of Effectiveness of Mulligan ‘MWM’ Technique Versus Kaltenborn Mobilization Technique on Pain and End Range of Motion in Patients with Adhesive Capsulitis of Shoulder Joint : A Randomized Controlled Trial

Comparison of Effectiveness of Mulligan ‘MWM’ Technique Versus Kaltenborn Mobilization Technique on Pain and End Range of Motion in Patients with Adhesive Capsulitis of Shoulder Joint : A Randomized Controlled Trial

An Evaluation of Supramaximally Loaded Eccentric Leg Press Exercise.

Harden, M, Wolf, A, Russell, M, Hicks, KM, French, D, and Howatson, G. An evaluation of supramaximally loaded eccentric leg press exercise. J Strength Cond Res 32(10): 2708-2714, 2018-High-intensity eccentric exercise is a potent stimulus for neuromuscular adaptation. A greater understanding of the mechanical stimuli afforded by this exercise will aid the prescription of future eccentric training regimens. This study sought to investigate the mechanical characteristics of supramaximally loaded eccentric exercise when using a custom-built leg press machine. Using a within-subject, repeated-measures design, 15 strength trained subjects (age, 31 ± 7 years; height, 180.0 ± 6.8 cm; body mass, 81.5 ± 13.9 kg) were assessed under 3 different conditions: low (LO), moderate (MOD), and high (HI) intensity, which were equivalent in intensity to 110, 130, and 150%, respectively, of peak force during an isometric maximal voluntary contraction (IMVC) performed on leg press at 90° knee flexion. All loading conditions demonstrated a similar pattern of mechanical profile; however, the variables underpinning each profile showed significant (p < 0.01) load-dependent response (LO vs. MOD, MOD vs. HI, LO vs. HI) for all variables, except for average acceleration. Average force associated with each loading conditions exceeded IMVC but equated to a lower intensity than what was prescribed. Repetitions under higher relative load intensity stimulated greater average force output, faster descent velocity, greater magnitude of acceleration, shorter time under tension, and a decline in force output at the end range of motion. This research provides new data regarding the fundamental mechanical characteristics underpinning supramaximally loaded eccentric leg press exercise. The information gathered in the study provides a foundation for practitioners to consider when devising loading strategies and implementing or evaluating supramaximally loaded eccentric exercise when using a similar exercise and device.

Effects of Instrument Assisted Soft Tissue Mobilization on Biceps Femoris Muscle Architecture

Instrument assisted soft tissue mobilization (IASTM) is a popular therapeutic modality that is often used to treat skeletal muscle restriction and injury. The efficacy and mechanism by which IASTM elicits a therapeutic effect is not fully understood. This study was designed to explore if any reported benefits of IASTM stem from changes in skeletal muscle architecture. PURPOSE: Examine the effects of IASTM on biceps femoris (BF) ultrasonography (US) baseline measurements of cross sectional area (CSA) and echo intensity (EI) as well as pennation angle (PA) at three different joint positions. Joint positions included 90°, mid- (MidROM), and end-range of motion (ROM) (EndROM). METHODS: Seventeen female participants (mean±SD: age=21.12±0.78 years) participated in this study. Participants were placed in a prone position for the IASTM treatment and for CSA and EI measures of the BF. Participants were also placed in a supine position, with the right hip and knee joints at 90° of flexion against a horizontal support for PA measurements. PA measurements were recorded at 90°, MidROM, and the EndROM joint positions. US settings were enhanced to improve image quality, including gain (50dB), depth (8cm), and frequency (12MHz). For the IASTM protocol, the BF received 3 sets of 7 strokes in both proximal and distal directions at a treatment angle of 45°. Paired samples t-tests [Time (Pre vs Post)] were used to analyze CSA and EI US data. A two-way repeated measures ANOVA [Joint position (90° vs MidROM vs EndROM) × Time (Pre vs Post)] was used to analyze PA data. An alpha value of P ≤ 0.05 was considered statistically significant for all comparisons. RESULTS: No significant difference was observed across time for CSA (p=0.220) or EI (p=0.515). Additionally, there was no significant joint position × time interaction (p=0.851) for PA. However, a significant main effect (p=0.001) for joint position was observed. Pairwise comparison revealed significant decreases in PA between 90° and MidROM (p=0.038), 90° and EndROM (p=0.001) and MidROM and EndROM (p=0.001). CONCLUSION: Although PA was altered with the corresponding changes in joint position, this was not a result of IASTM. These results indicate that a single bout of IASTM may not evoke architectural change in the hamstrings as measured by ultrasonography.

A MECHANISM FOR LIGAMENTUM TERES INJURIES IN FEMOROACETABULAR IMPINGEMENT: AN ANATOMICAL STUDY

Femoroacetabular impingement can produce abnormal biomechanics that lead to compensatory injuries around the hip and pelvis. Ligamentum teres pathologies are commonly associated with these bony deformities but a mechanism for injury has not been described in the literature. The purpose of this study was to describe a potential mechanism behind ligamentum teres injury and impingement between the femoral neck and acetabulum. Laboratory controlled cadaveric study. Twenty-six hips from 15 embalmed cadavers (8 male; 7 female) with lifespans between 55-93 years were skeletonized. The hip was placed in 90 ° flexion and 0 ° abduction/adduction and internally rotated until the femoral head neck contacted the acetabulum. This position of impingement with respect to internal rotation was recorded with a goniometer. The hip was then further internally rotated until end range of motion was achieved and again the position of internal rotation recorded with a goniometer. The positions of internal rotation at which impingement occurred (mean 9 °; SD 4.2; Range -2 ° to 15 °) when compared to end range (mean 21 °; SD 5.7; Range 5 ° to 27 °) were significantly different (p<0.005; t = 14.8). In all the hips, after impingement occurred the site of bony contact between the femoral neck and acetabulum acted as a pivot point. The femoral head was levered inferiorly with a loss of the rotational center within the acetabulum, as internal rotation continued. This movement of the femoral head caused the ligamentum teres to tighten and restricted further movement. Movement into internal rotation beyond this end position caused rupture of the ligamentum teres. Internal rotation range of motion can occur beyond the position of impingement and resulted in abnormal inferior movement of the femoral head and tightening of the ligament teres. This study provides cadaveric evidence for the mechanism of ligamentum teres injury in those with who engage in activities that required motion beyond the point of impingement.

Dynamic "Range of Motion" Hindlimb Stretching Disrupts Locomotor Function in Rats with Moderate Subacute Spinal Cord Injuries.

Joint contractures and spasticity are two common secondary complications of a severe spinal cord injury (SCI), which can significantly reduce quality of life, and stretching is one of the top strategies for rehabilitation of these complications. We have previously shown that a daily static stretching protocol administered to rats at either acute or chronic time points after a moderate or moderate-severe T10 SCI significantly disrupts their hindlimb locomotor function. The objective of the current study was to examine the effects of dynamic range of motion (ROM) stretching on the locomotor function of rats with SCI as an alternative to static stretching. Starting at 6 weeks post-injury (T10 moderate contusion) eight adult Sprague-Dawley rats were subjected to hindlimb stretching for 4 weeks. Our standard stretching protocol (six maneuvers to stretch the major hindlimb muscle groups) was modified from 1 min static stretch-and-hold at the end ROM of each stretch position to a dynamic 2 sec hold, 1 sec release rhythm repeated for a duration of 1 min. Four weeks of daily (5 days/week) dynamic stretching led to significant disruption of locomotor function as assessed by the Basso, Beattie, Bresnahan (BBB) Open Field Locomotor Scale and three-dimensional (3D) kinematic and gait analyses. In addition, we identified and analyzed an apparently novel hindlimb response to dynamic stretch that resembles human clonus. The results of the current study extend the observation of the stretching phenomenon to a new modality of stretching that is also commonly used in SCI rehabilitation. Although mechanisms and clinical relevance still need to be established, our findings continue to raise concerns that stretching as a therapy can potentially hinder aspects of locomotor recovery.

Cervical motion segment contributions to head motion during flexion\\extension, lateral bending, and axial rotation

Background ContextCervical spine segmental contributions to motion may reveal movement abnormalities associated with whiplash, disc herniation, disc arthroplasty, or fusion. PurposeThe objective of this study was to determine the cervical spine segmental contributions to head flexion\\extension, lateral bending, and axial rotation during dynamic motion in young, healthy individuals. Study DesignThe study design was a descriptive control study. Patient SampleTwenty-nine young (20–35 years of age) healthy individuals comprised the patient sample. Outcome MeasuresPhysiologic measures of contributions from each cervical motion segment to the primary head rotation were the outcome measures for this study. MethodsTwenty-nine healthy participants performed full range of motion (ROM) flexion\\extension, lateral bending, and axial rotation while biplane radiographs were collected at 30 images per second. Surface-based markers were used to determine head kinematics for each movement, and a validated volumetric model-based tracking technique was used to determine intervertebral kinematics. Contributions from each cervical motion segment to the primary head rotation were determined continuously during each of the three head movements. This study was funded by Synthes Spine (F). ResultsFor each head movement, motion segments in the lower cervical spine increased their contributions to head motion near the end of the ROM. Cervical motion segment contributions to left and right lateral bending were mirror images of each other, as were contributions to left and right axial rotation. However, cervical motion segment contributions to flexion were not mirror images of the contributions to extension. ConclusionsCervical motion segment contributions to head motion change over the full ROM and cannot be accurately characterized solely from endpoint data. The continuously changing segmental contributions suggest that the compressive and shear loads applied to each motion segment also change over the ROM. The clinical implication of increased contributions from the inferior motions segments near the end ROM is that the clinician may advise the patient to avoid end ROM positions to lessen the demand on the discs of inferior motion segments.

Acute Effects of Stretching on Passive Properties of Human Gastrocnemius Muscle-Tendon Unit: Analysis of Differences Between Hold-Relax and Static Stretching.

Hold-relax stretching (HRS) and static stretching (SS) are commonly used to increase joint range of motion (ROM) and decrease muscle stiffness. However, whether there are differences between acute effects of HRS and SS on end ROM, passive torque, and muscle stiffness is unclear. In addition, any differences between the mechanisms by which HRS and SS lead to an increase in end ROM are unclear. To compare the acute effects of HRS and SS on the passive properties of the gastrocnemius muscle-tendon unit (MTU), end ROM, passive torque, and muscle stiffness in vivo and to investigate the factors involved in increasing end ROM. Crossover experimental design. 30 healthy men (21.7 ± 1.2 y) with no history of neuromuscular disease or musculoskeletal injury involving the lower limbs. Both HRS and SS of 30 s were repeated 4 times, lasting a total of 2 min. End ROM, passive torque, and muscle stiffness were measured during passive ankle dorsiflexion using a dynamometer and ultrasonography before and immediately after HRS and SS. The results showed that end ROM and passive torque at end ROM significantly increased immediately after both HRS and SS, whereas muscle stiffness significantly decreased. In addition, the percentage change in passive torque at end ROM on use of the HRS technique was significantly higher than that after use of the SS technique. However, the percentage change in muscle stiffness after SS was significantly higher than that with HRS. These results suggest that both HRS and SS can effectively decrease muscle stiffness of the gastrocnemius MTU and that HRS induces a change in the passive torque at end ROM--i.e., sensory perception--rather than changing muscle stiffness.

Quantifying strain in the vertebral artery with simultaneous motion analysis of the head and neck: A preliminary investigation

BackgroundSpontaneous vertebral artery dissection has significant mortality and morbidity among young adults. Unfortunately, causal mechanisms remain unclear.The purpose of this study was to quantify mechanical strain in the vertebral artery while simultaneously capturing motion analysis data during passive movements of the head and neck relative to the trunk during spinal manipulation and cardinal planes of motion. MethodsEight piezoelectric crystals (four per vertebral artery) were sutured into the lumen of the left and right vertebral arteries of 3 cadaveric specimens. Strain was then calculated as changes in length between neighboring crystals from a neutral head/neck reference position using ultrasound pulses. Simultaneously, passive motion of the head and neck on the trunk was captured using eight infrared cameras. The instantaneous strain arising in the vertebral artery was correlated with the relative changes in head position. FindingsStrain in the contralateral vertebral artery during passive flexion-rotation compared to that of extension-rotation is variable ([df=32]: −0.61<r<0.55). Peak strain does not coincide with peak angular displacement during spinal manipulation and cardinal planes of motion. Axial rotation displayed the greatest amount of strain. The greatest amount of strain achieved during spinal manipulation was comparably lower than strains achieved during passive end range motions and previously reported failure limits. InterpretationThe results of this study suggest that vertebral artery strains during head movements including spinal manipulation, do not exceed published failure strains. This study provides new evidence that peak strain in the vertebral artery may not occur at the end range of motion, but rather at some intermediate point during the head and neck motion.