Trunk Loading Research Articles

How the multiplanar trunk resistance affects the dynamic postural control during single-leg vertical jumps in college athletes with poor movement quality

BACKGROUND: Poor movement quality of the trunk and the lower limbs as well as dynamic postural control have a strong relation with non-contact injuries in sport. Aiming to reduce the risk of injuries, training approaches using loaded jumps with trunk resistance have been proposed. AIM: To describe how a multiplanar trunk load affects the dynamic postural control and the peak vertical ground reaction force of college athletes with poor movement quality of the trunk and the lower limbs. METHOD: Center of Pressure (COP) variables and peak vertical ground reaction force of 24 female college athletes during single-leg jumps with and without a trunk resistance were compared. RESULTS: There was a significant decrease of the COP displacement (p=0.006), RMS (p=0.009) and velocity (p=0.007) in the anteroposterior direction, and an increase of the COP displacement (p=0.016), RMS (p=0.043) and velocity (p=0.043) in the mediolateral direction, with a moderate effect size. No significant difference was found in the peak vertical ground reaction force. CONCLUSION: Exercises involving multiplanar trunk resistance may negatively impact dynamic postural control in women with poor movement quality.

Effects of added trunk load on the in vivo kinematics of talocrural and subtalar joints during landing

BackgroundLanding from heights is a common movement for active-duty military personnel during training. And the additional load they carry while performing these tasks can affect the kinetics and ankle kinematic of the landing. Traditional motion capture techniques are limited in accurately capturing the in vivo kinematics of the talus. This study aims to investigate the effect of additional trunk load on the kinematics of the talocrural and subtalar joints during landing, using a dual fluoroscopic imaging system (DFIS). MethodsFourteen healthy male participants were recruited. Magnetic resonance imaging was performed on the right ankle of each participant to create three-dimensional (3D) models of the talus, tibia, and calcaneus. High-speed DFIS was used to capture the images of participants performing single-leg landing jumps from a height of 40 cm. A weighted vest was used to apply additional load, with a weight of 16 kg. Fluoroscopic images were acquired with or without additional loading condition. Kinematic data were obtained by importing the DFIS data and the 3D models in virtual environment software for 2D–3D registration. The kinematics and kinetics were compared between with or without additional loading conditions. ResultsDuring added trunk loading condition, the medial-lateral translation range of motion (ROM) at the talocrural joint significantly increased (p < 0.05). The subtalar joint showed more extension at 44–56 ms (p < 0.05) after contact. The subtalar joint was more eversion at 40–48 ms (p < 0.05) after contact under the added trunk load condition. The peak vertical ground reaction force (vGRF) significantly increased (p < 0.05). ConclusionsWith the added trunk load, there is a significant increase in peak vGRF during landing. The medial-lateral translation ROM of the talocrural joint increases. And the kinematics of the subtalar joint are affected. The observed biomechanical changes may be associated with the high incidence of stress fractures in training with added load.

Effects of Laser and Sacroiliac Joint Mobilization for Sacroiliac Joint Dysfunction

To evaluate the effects of laser and sacroiliac join mobilization for sacroiliac joint dysfunction.The SI Joint`s primary functions are to provide to distribute trunk load to the lower limbs. Lowback discomforts are frequently caused by sacroiliac joint dysfunction (SI) Joint, which can bedifficult to diagnose. Prolonged standing or sitting postures can also make pain worse. Low Intensity Laser Therapy also known as Low Level Laser Therapy is thought to work by inducing a photochemical-reaction (Response) to light (Laser) Physiotherapist frequently Recommend spine mobilization to treat Musculoskeletal Problems. The Amplitude of Oscillating mobilization can be classified as considerable (GradesII and III) or little (Grades I and IV) depending on the possible range of motion. 5 Large amplitude oscillations excite more mechanoreceptors and hence reduce pain more effectively than small amplitude oscillations. To evaluate the effects of laser therapy and laser therapy with sacroiliac joint mobilization in patient with sacroiliac joint dysfunction. The total number of test subjects was 40. The Group(A) 20 Samples) and Group(B) 20 Samples, both groups pre and post-test values noted NPRS scale. Group-A Laser therapy was given by patient being in prone lying position and Group-B Laser therapy with sacroiliac joint mobilization techniques was given in being pronelying position. Both Groups treatment Will be given 4 weeks for Thrice a week for 30 minutes. This study was conducted as a experimental study. The sample were collected by convenient sampling technique. The data that had been gathered was statistically analyzed using an unpaired t-test. Compared to the laser group, the Laser with sacroiliac joint mobilization group exhibits significant effects in lowering pain and improving physical functional activity, as assessed by NPRS scale. It is concluded that laser therapy with sacroiliac joint mobilization technique was found to be more effective than laser therapy in sacroiliac joint dysfunction. Key Words: Sacroiliac joint dysfunction, Laser, Maitland mobilization Technique

Immediate effect of trunk flexion and extension isometric exercise using an external compression device on electromyography of the hip extensor and trunk range of motion of healthy subjects

BackgroundSacroiliac joints (SIJs) transmitted trunk load to lower extremities through the lumbopelvis. External compression devices across the SIJs could provide stability to the SIJs. A previous study established that using a device known as Active Therapeutic Movement version 2 (ATM®2) has been developed to improve pain and joint range of motion (ROM) in patients with LBP. However, no study has examined the physiological change in the muscle through ATM®2-based exercise thus far. This study aimed to determine the immediate effects of ATM®2 exercise on the contraction timing, back extension endurance, muscle fatigue, and trunk ROM of lumbar and lower limb muscles in healthy subjects.MethodsThirty-six healthy subjects (mean age = 23.16 ± 2.3) volunteered to participate in this study. Subjects were instructed to perform ROM test using sit and reach test, back extensor endurance test using Biering-Sorensen test, erector spinae (ES), lumbar multifidus (LM) fatigue and onset time of Gluteus maximus (GM) in prone hip extension using electromyography before and after trunk flexion and extension isometric exercises.ResultsThe ROM in trunk flexion showed a significant increase of 7.9% after exercise compared to that before exercise (p < 0.05). Relative GM contraction onset timing significantly decreased after exercise (p < 0.05). The result of the Sorensen test after exercise showed a trend of increase in duration time. Muscle fatigue in the LM, however, showed a significant increase (p < 0.05), whereas muscle fatigue in the ES was reduced without statistical significance.ConclusionsThe results base on this study showed that exercise-based on ATM®2 is an effective exercise protocol with an effect on the biomechanics of healthy subjects.Clinical trial registration numbers KCT0006728. Clinical trial registration date: 09/11/2021.

Effect of Six-Week Resistance and Sensorimotor Training on Trunk Strength and Stability in Elite Adolescent Athletes: A Randomized Controlled Pilot Trial.

Intervention in the form of core-specific stability exercises is evident to improve trunk stability. The purpose was to assess the effect of an additional 6 weeks sensorimotor or resistance training on maximum isokinetic trunk strength and response to sudden dynamic trunk loading (STL) in highly trained adolescent athletes. The study was conducted as a single-blind, 3-armed randomized controlled trial. Twenty-four adolescent athletes (14f/10 m, 16 ± 1 yrs.;178 ± 10 cm; 67 ± 11 kg; training sessions/week 15 ± 5; training h/week 22 ± 8) were randomized into resistance training (RT; n = 7), sensorimotor training (SMT; n = 10), and control group (CG; n = 7). Athletes were instructed to perform standardized, center-based training for 6 weeks, two times per week, with a duration of 1 h each session. SMT consisted of four different core-specific sensorimotor exercises using instable surfaces. RT consisted of four trunk strength exercises using strength training machines, as well as an isokinetic dynamometer. All participants in the CG received an unspecific heart frequency controlled, ergometer-based endurance training (50 min at max. heart frequency of 130HF). For each athlete, each training session was documented in an individual training diary (e.g., level of SMT exercise; 1RM for strength exercise, pain). At baseline (M1) and after 6 weeks of intervention (M2), participants’ maximum strength in trunk rotation (ROM:63°) and flexion/extension (ROM:55°) was tested on an isokinetic dynamometer (concentric/eccentric 30°/s). STL was assessed in eccentric (30°/s) mode with additional dynamometer-induced perturbation as a marker of core stability. Peak torque [Nm] was calculated as the main outcome. The primary outcome measurements (trunk rotation/extension peak torque: con, ecc, STL) were statistically analyzed by means of the two-factor repeated measures analysis of variance (α = 0.05). Out of 12 possible sessions, athletes participated between 8 and 9 sessions (SMT: 9 ± 3; RT: 8 ± 3; CG: 8 ± 4). Regarding main outcomes of trunk performance, experimental groups showed no significant pre–post difference for maximum trunk strength testing as well as for perturbation compensation (p > 0.05). It is concluded, that future interventions should exceed 6 weeks duration with at least 2 sessions per week to induce enhanced trunk strength or compensatory response to sudden, high-intensity trunk loading in already highly trained adolescent athletes, regardless of training regime.

К МЕТОДИКЕ УСТАНОВЛЕНИЯ ИНТЕНСИВНОСТИ ВЫДЕЛЕНИЯ ТЕРПЕНТИНА ПРИ ЕГО ЗАГОТОВКЕ В ОСУШАЕМЫХ СОСНЯКАХ

An experimental open-type tapping was carried out in pine stands located in the Sokolsky district of the Vologda region. The objects of study are represented by plantations located on the sites, passed in 1972 by hydrotechnical reclamation, as well as similar forests after continuous thinning. The dominant species in the tree layer is pine, the share of spruce and birch does not reach 10%. The release of turpentine was studied in pine forests on a mesotrophic peat deposit. The tapping was carried out using the ascending method of applying the substrates. The main attention was paid to improving the method for determining the resin productivity of Scots pine. In the course of the study, the following tasks were solved: 1) four permanent test plots were laid in drained pine plantations, in addition, continuous thinning was performed on two sites; 2) for research purposes, an experimental double-sided harvesting of pine turpentine was carried out on each trial plot; 3) the influence of hydrotechnical reclamation and thinning on the amount of released pine turpentine has been determined; 4) specifying coefficients have been developed for the mathematical calculation (forecast) of turpentine yield with a 50% trunk load with tapping cuts. Based on the results of the study, a number of correction factors have been proposed to determine the resin productivity of pines, taking into account their taxation diameter, since the mathematical calculation of the turpentine yield under a trunk load with tapping cuts of 50% carr is often overestimated. The positive effect of hydrotechnical reclamation on the increase in the breast height diameter of pine was confirmed. The average yield of pine resin is about 22% higher, relative to the stand without silvicultural care, in a drained pine forest after silvicultural maintenance

The variations and degenerative changes of sacroiliac joints in asymptomatic adults.

The sacroiliac joint has a structure in which the direction of the load relative to the articular surface is irrational, as the joint surface is not perpendicular to the trunk load axis; it is likely to incur more degenerative changes than other weight-bearing joints. This retrospective study consisted of a total of 145 cases - 104 (71.7%) men and 41 (28.3%) women - who were referred to Gaziantep University Medical Faculty Radiology Department Polyclinic for pelvic computed tomography (CT) from 2013 to 2018. The mean age was 33.5 years (range: 18-60 years). Pelvis CT images were performed according to the exclusion criteria specified by the experienced orthopaedic surgeon. Patients were excluded from the study if they were younger than the age of 18, had a condition involving the sacroiliac joint, had an endocrine disorder, or had a history of a trauma affecting the pelvis CT examination. In this current study, six types of anatomic variations were detected. Iliosacral complex variation has been determined as the most common type of variation. The incidence of variations of sacroiliac joint in all cases was 28.9%. Degenerative changes were seen in 5.5% of patients fewer than 30 years of age. When it comes to the patients whose age range is 30-60, the percentage of the degenerative changes is 12.4%. In patients who were 30 years and older, the prevalence of degenerative changes increased progressively with increasing age. In this study, it is thought that the knowledge of variations in normal population and degenerative changes will contribute to the better understanding of normal morphological structure of sacroiliac joint and to the anatomical literature. It's seen that there is not a statistically significant relationship between degenerative changes and anatomical variations.

Unilaterally Implemented Trunk Modification Associated With Asymmetrical Increase In Spinal Load

Trunk modification (TM) is associated with reduced knee adduction moment during gait in both healthy and symptomatic individuals. Reported reductions are dependent on the magnitude of modification implemented. Evidence however suggests that increased trunk motion augments structural loading at the spine. Despite the positive adaptations at the knee, potential unanticipated changes in spinal load are yet to be investigated. PURPOSE: To investigate changes in trunk joint reaction force (JRF) during ipsilateral (IP) and contralateral (CT) stance phases subsequent to implementing unilateral subject-specific TM. METHODS: 19 healthy participants (26.7±4.8 years; 1.69±0.17 m; 72.3±11.8 kg) were recruited. Trunk lean was implemented towards the side of the preferred kicking limb. Participants average trunk angle (TA) was assessed during 10 baseline trials using a motion capture system (200Hz) and force plates (1000Hz). Subject-specific TA range was determined by adding 1-3 standard deviations (small), and 3-5 standard deviations (large) to baseline value. Participants completed 5 trials using both small and large subject-specific TM angles. Real-time TA projected as a line graph which was visible to participants during TM trials reinforced performance. Visual 3D was used to deliver feedback and determine trunk JRF (N/kg). Changes to trunk JRF was assessed using a Friedman test with Wilcoxon signed-ranked test and Bonferroni-adjusted significance level. Analyses were conducted using a significance level of p<0.017. RESULTS: Peak lateral JRF during IP and CT stance were significantly greater during TM trials (χ2 (2) = 32.9, and 30.7, p<0.001 respectively). Participants experienced increased lateral JRF during both IP (d=1.5, and d=1.7, small and large TM respectively), and CT (d=1.6, and d=1.7, small and large TM respectively) compared to baseline. CONCLUSION: Changes in trunk JRFs are indicative of elevated spinal loads. During CT stance, lateral JRF in the direction of the modified side persisted which is indicative of continued asymmetric trunk load. Findings suggest TM could result in detrimental adaptations and may be contraindicated for certain individuals. Further research employing longitudinal design is needed to investigate if observed acute changes are transient in nature.

Increased Liveliness of Trunk Muscle Responses in Elite Kayakers and Canoeists.

Trunk stability functions play an important role in sport and everyday movements. The aim of this study was to analyze trunk strength, trunk muscles onset of activity, and rate of electromyographic rise (RER) in the case of self-inflicted and unexpected trunk loading. Thirty-two healthy young adults (16 elite kayakers/canoeists and 16 non-athletes) were measured with a multi-purpose diagnostic machine. Trunk strength was assessed in standing position. Trunk muscles onset of activity and RER were assessed through unexpected loading over the hands and rapid shoulder flexion, respectively. In comparison with non-athletes, kayakers/canoeists did not significantly differ in trunk strength and showed lower trunk extension/flexion strength ratio (p = 0.008). In general, trunk muscles onset of activity did not significantly differ between the groups. On the contrary, kayakers/canoeists showed higher RER mean values in all the observed muscles (p < 0.041), except in multifidus muscle during self-inflicted movements. Similarly, higher RER variability was observed in the majority of the observed muscles among kayakers/canoeists. Higher RER among kayakers/canoeists could represent a protective mechanism that ensures spine stability and prevents low back pain.

Trunk coordination in people with low back pain during goal-directed repetitive sagittal trunk movements

Purpose: Repetitive sagittal trunk movements represent an occupational risk factor leading to cumulative trunk loading which can be associated with the development of low back pain (LBP) (Coenen et al., 2014). A possible mechanism causing an increased loading effect in LBP relates to impaired adaptation of speed control during goal-directed trunk movements (Zhou et al., 2016). This study explored trunk temporal coordination pattern during repetitive goal-directed sagittal trunk movements in LBP people compared to asymptomatic control.

Sudden gait perturbations elicit sex-specific neuromuscular trunk responses in persons with low back pain

Persons with low back pain (LBP) exhibit delayed trunk muscle onset and increased co-contractions as a response to quasi-static and dynamic sudden trunk loading in comparison to back-healthy controls. Although LBP is more prevalent in females, sex-specific responses have not been well documented. Therefore, the purpose was to explore sex-specific neuromuscular differences, to gait perturbation, in LBP patients.Twenty-nine LBP patients (12m/17f;31 ± 10yrs; 174 ± 12 cm; 71 ± 16 kg) walked on a split-belt treadmill at 1 m/s, while 15 right-sided random perturbations (treadmill-belt decelerating, 40 m/s2, 50 ms duration; 200 ms after heel contact) were applied. Muscle activity was assessed using a 12-lead surface EMG (6 back/6 abdominal muscles; 4000 Hz). EMG-RMS [%] (0–200 ms after perturbation) was calculated and normalized to RMS of unperturbed gait for each muscle. Furthermore, muscle onsets (ms) were determined. Two-way ANOVA (factors: sex/muscle) was applied to account for sex differences in main outcomes.EMG-RMS (amplitudes; mean) ranged from 356% to 901% in males and 349% to 694% in females representing a significant interaction effect (sex * muscle: p = 0.017). Post-hoc analysis revealed significant differences for EMG-RMS analysis of rectus abdominis left (p = 0.043; f > m) as well as obliques externus right/left (p = 0.018/p = 0.005; f < m). In the time domain, females showed overall, shorter (mean: 90 ± 16 ms) response times compared to males (mean: 98 ± 22 ms, sex effect: p < 0.0001).In this LBP population, abdominal muscle activation discriminated females from males. Specifically, females had higher activity of the rectus abdominis muscles and lower activation of the externus oblique muscles. These different activation strategies might be relevant to the development of sex-specific intervention strategies.

Abdominal draw-in maneuver changes neuromuscular responses to sudden release from trunk loading in patients with non-specific chronic low back pain

BackgroundAbdominal draw-in maneuver (ADIM) has been recommended to achieve appropriate trunk muscle response for patients with non-specific chronic low back pain (CLBP). However, it has remained unclear whether the intervention with ADIM could change the trunk muscle response to sudden release from loading, which is considered to contribute mechanical circumstances to low back pain. The purpose of the present study was to investigate the effects of the intervention with ADIM on electromyography (EMG) activities of trunk muscles following sudden release from loading. MethodsSeventeen subjects with non-specific CLBP participated. Subjects resisted trunk flexion or extension loading in semi-seated position, and then the loading was suddenly released. EMG recordings of 6 trunk muscles were acquired using a wireless surface EMG system. Onset and offset times were calculated from the EMG data. The intervention with ADIM was provided for 4 weeks. The onset and offset times were compared between pre- and post-intervention with ADIM. ResultsAt the post-intervention, the onset of trunk flexors following release from trunk flexion loading became significantly earlier than pre-intervention (P = 0.028). The offset of flexors following release from trunk extension loading of post-intervention was significantly earlier than that of pre-intervention (P = 0.001). ConclusionsWe showed that the intervention with ADIM changed the EMG activity of trunk flexors in response to sudden release from loading. These results suggest a possibility that ADIM might be effective to improve the neuromuscular control of trunk flexors for the treatment of young patients with non-specific CLBP.

Ease of EVs: Exploring factors that influence battery consumption

Battery electric vehicles (BEVs) are becoming increasingly popular, showing annual sales growth, yet adoption is still limited. Maximizing distance driven between charges can improve user perceptions and usability of BEVs. Therefore, the ability to identify factors that influence a BEV's state of charge (SOC) in a naturalistic, experimental environment contribute to accomplishing transit sustainability. This study explores whether BEV drivers’ use of five different energy regenerative braking modes, in conjunction with other potential influencing factors (e.g., trunk load), make a significant difference on the SOC. Using a randomized 3-factor factorial design, two drivers traveled the same path 20 times each, exceeding 160 miles each, for over 320 total miles of experimentation in a 2015 Volkswagen (VW) e-Golf. Significant differences were found between regenerative braking settings and the 3-way interactions between driver, load, and setting. Additional analysis suggests that only two regenerative braking settings (i.e., low regenerative braking and high regenerative braking) are actually required in addition to traditional braking, as the SOC does not change between all four regenerative braking settings. Furthermore, a posteriori, it was found that external temperature played a significant role in the SOC. Future research should focus on empirically detailing these differences between BEV drivers and SOC, validating and improving theoretically or simulation derived contexts. Ultimately, in an effort to transition society to a BEV future, this research seeks to harness patterns that affect a BEV’s range, in order to maximize traveling distance between charges, to help reduce the threshold of user adoption.

Trunk peak torque, muscle activation pattern and sudden loading compensation in adolescent athletes with back pain

To evaluate trunk peak torque and muscle activation pattern during isokinetic and sudden trunk loading (STL) between adolescent athletes with/without back pain. Nine adolescent athletes with back pain (BP) (m/f 2/7; 15.6 ± 1.2y; 177 ± 9cm; 67 ± 13kg; 22.5 ± 9.8h/week) and nine matched controls (m/f 2/7; 15.7 ± 1.4y; 177 ± 12cm; 65 ± 9kg; 16.5 ± 8.0h/week training) were included. Trunk strength in rotation and flexion/extension was assessed. Sudden trunk loading was measured during eccentric extension and rotation (30∘/s) with additional perturbation. Trunk muscle activity was measured using a 12 lead-EMG (electromyography). Main outcome measures were peak torque [Nm] and MVC normalized EMG-amplitudes (RMS [%]) for each muscle. Additionally, the mean EMG-RMS for four areas of the trunk was calculated (right/left ventral, right/left dorsal). Back pain showed lower trunk peak torque for all conditions in extension/flexion, but not for rotation. EMG amplitudes were increased for BP athletes with statistical significant differences for dorsal muscles in rotation and extension (p< 0.0042), not for ventral muscles in flexion. The evaluation of strength and muscle activity in isokinetic and sudden trunk loading presents altered trunk function in adolescent back pain athletes. Training interventions focusing on trunk strength and muscular activation pattern appears reasonable.

Repetitive trunk loading leads to faster trunk movement in response to external perturbation

The purpose of the present study was to examine trunk movement pattern responses to mechanical perturbation before and after two different repetitive trunk flexion-extension loading schemes. Spatial and temporal parameters were studied to understand the trunk recovery from an anteriorly directed perturbation. Eighteen male and female subjects (18–27 yrs) participated in active and passive trunk flexion-extension, performed seven days apart. Subjects performed 60 trunk flexion-extension repetitions in each condition. Subjects either volitionally moved their trunks (active condition) or relaxed while a dynamometer controlled the movements (passive condition). Trunk perturbations occurred before and immediately after two 30 repetition sessions. Initial responses included latency measures of trunk displacement and peak trunk velocity (VP). Temporal measures included perturbation onset to initial trunk movement (TD), movement initiation to VP (TMIPV), and perturbation onset to VP (TPPV). Recovery measures included peak recovery velocity (VPR), recovery time (TR), velocity slope (VS), and recovery slope (RS). Differences between loading sessions were present for TPPV (p < .05), TR (p < .05), and RS (p < .05). Overall, the results indicate repetitive loading leads to lower resistance to perturbation, but faster recovery from perturbation although no differences to active or passive repetitive loading was observed.

Sensorimotor Exercises and Enhanced Trunk Function: A Randomized Controlled Trial.

The aim of this study was to investigate the effect of a 6-week sensorimotor or resistance training on maximum trunk strength and response to sudden, high-intensity loading in athletes.Forty-three healthy, well-trained participants were randomized into sensorimotor (SMT; n=11), resistance training (RT; n=16) and control groups (CG; n=16). Treatment groups received either sensorimotor training (SMT) or resistance training (RT) for 6 weeks, 3 times a week. At baseline and after 6 weeks of intervention, participants' maximum isokinetic strength in trunk rotation and extension was tested (concentric/eccentric 30°/s). In addition, sudden, high-intensity trunk loading was assessed for eccentric extension and rotation, with additional perturbation. Peak torque [Nm] was calculated as the outcome.Interventions showed no significant difference for maximum strength in concentric and eccentric testing (p>0.05). For perturbation compensation, higher peak torque response following SMT (Extension: +24 Nm 95%CI±19 Nm; Rotation: +19 Nm 95%CI±13 Nm) and RT (Extension: +35 Nm 95%CI±16 Nm; Rotation: +5 Nm 95%CI±4 Nm) compared to CG (Extension: -4 Nm 95%CI±16 Nm; Rotation: -2 Nm 95%CI±4 Nm) was present (p<0.05).This study showed that isokinetic strength gains were small, but that significant improvements in high-intensity trunk loading response could be shown for both interventions. Therefore, depending on the individual's preference, therapists have two treatment options to enhance trunk function for back pain prevention.

Repetitive Trunk Loading Leads to Faster Trunk Movement in Response to External Perturbation

Repetitive Trunk Loading Leads to Faster Trunk Movement in Response to External Perturbation

The effect of task characteristics on the choice to lean, upper body postures and joint loading during simulated automotive manufacturing tasks with one-handed, sub-maximal exertions

The purpose of this study was to investigate the preferred leaning postures, while giving participants the choice to lean when completing tasks with constrained reaches. Twenty female participants completed a variety of different exertions with and without a leaning surface available. The frequency of choice to lean changed with task hand location. The long reaching task hand locations resulted in the most frequent choice to lean, and this decreased trunk and task arm shoulder loading, while allowing the participant to get closer to the task. These findings will be of use to industry in validating future leaning posture prediction software to help guide leaning posture estimates during proactive risk assessments.

Increased spinal height using propped slouched sitting postures: Innovative ways to rehydrate intervertebral discs

BackgroundUpright and slouched sitting are frequently adopted postures associated with increased intradiscal pressure, spinal height loss and intervertebral disc pathology. ObjectivesTo examine the effects of two sustained propped slouched sitting (PSS) postures on spinal height after a period of trunk loading. MethodsThirty-four participants without a history of low back pain (LBP) were recruited (age 24.4 ± 1.6 years). Subjects sat in (1) PSS without lumbar support and (2) PSS with lumbar support for 10 min, after a period of trunk loading. Spinal height was measured using a stadiometer. ResultsMean spinal height increase during PSS without lumbar support was 2.94 ± 3.63 mm and with lumbar support 4.74 ± 3.07 mm. ConclusionsBoth PSS with and without lumbar support significantly increased spinal height after a period of trunk loading (p < 0.001). Such PSS postures can provide a valuable alternative to upright sitting and may be recommended for recovering spinal height in the working environment following periods of loading.

Directional preference of activation of abdominal and paraspinal muscles during position-control tasks in sitting

Controversy exists in the literature regarding antagonist activity of trunk muscles during different types of trunk loading, and the direction-specificity of activation of trunk muscles, particularly the deeper trunk muscles. This study aimed to systematically compare activation of a range of trunk muscles between directions of statically applied loads, and to consider the impact of breathing in this activation. In a semi-seated position, 13 healthy male participants resisted moderate inertial loads applied to the trunk in eight different directions. Intramuscular electromyography was recorded from eight abdominal and back muscles on the right side during 1s prior to peak inspiration/expiration. All muscles demonstrated a directional preference of activation. No muscle displayed antagonistic activation during loading conditions of an intensity that exceded that recorded in upright sitting without a load. During these moderate intensity sustained efforts, trunk muscle activation varied little between respiratory phases. Antagonistic muscle activation of amplitude equivalent to the activation recorded in upright sitting without load is sufficient to maintain control of the spine during predictable and sustained low load tasks.