Machine learning-based detection of acute psychosocial stress from body posture and movements.

Investigating acute stress responses is crucial to understanding the underlying mechanisms of stress. Current stress assessment methods include self-reports that can be biased and biomarkers that are often based on complex laboratory procedures. A promising additional modality for stress assessment might be the observation of body movements, which are affected by negative emotions and threatening situations. In this paper, we investigated the relationship between acute psychosocial stress induction and body posture and movements. We collected motion data from N = 59 individuals over two studies (Pilot Study: N = 20, Main Study: N = 39) using inertial measurement unit (IMU)-based motion capture suits. In both studies, individuals underwent the Trier Social Stress Test (TSST) and a stress-free control condition (friendly-TSST; f-TSST) in randomized order. Our results show that acute stress induction leads to a reproducible freezing behavior, characterized by less overall motion as well as more and longer periods of no movement. Based on these data, we trained machine learning pipelines to detect acute stress solely from movement information, achieving an accuracy of 75.0 ± 17.7 % (Pilot Study) and 73.4 ± 7.7 % (Main Study). This, for the first time, suggests that body posture and movements can be used to detect whether individuals are exposed to acute psychosocial stress. While more studies are needed to further validate our approach, we are convinced that motion information can be a valuable extension to the existing biomarkers and can help to obtain a more holistic picture of the human stress response. Our work is the first to systematically explore the use of full-body body posture and movement to gain novel insights into the human stress response and its effects on the body and mind.

Joint knee loads during squat with constant or variable resistance in males. A clinical trial.

BACKGROUND: In the squat movement, the use of constant resistance (CR) generates greater compression and shear forces close to 90° of knee flexion, increasing joint overload. However, when used variable resistance (VR) there is no consensus about the effect of knee joint load. The aim of this study was to compare knee torques using constant or variable resistance during the squat exercise. METHODS: Twenty-one healthy male subjects (mean age, 24 [SD, 3] years; height, 1.76 [SD, 0.04] m), who practice squats during strength training routine. Were simultaneously record data from the platform force and tridimensional kinematic to obtain torques around knee. 15 repetitions were performed up to maximum knee flexion with the use of variable (RV) or constant (CR) resistance in a single session. RESULTS: Significant differences regarding the angles only in the sagittal plane at the end of the ascending phase of the squat, with less knee extension in the VR condition. In the sagittal and frontal planes, lower values of extensor and abductor torque were found in the VR condition at the angles of greater knee flexion. CONCLUSION: The use of variable resistance compared to constant resistance seems to be an alternative to be considered when the objective is to minimize the internal loads on the knee joint in exercises such as the squat in amplitudes of greater flexion. This study indicated that VR helps subjects who are learning the squat movement, enabling the application of this knowledge in physical therapy or physical training clinics.

Optimization of the seat position for a personal vehicle equipped with a crankset: pilot study.

The aim of the study was to optimize the seat for a personal vehicle equipped with a crankset mechanism, meant for everyday use. The inclination of the seat backrest was selected on the basis of theoretical considerations. Then dynamic tests were carried out on a group of young, healthy men in order to verify the ergonomic aspects of the seat position in relation to the crankset and determine the efficiency of the human-mechanism system with a load of 50 W. The data obtained from the dynamic tests were subject to statistical analysis. Research has shown that higher seat positions result in statistically higher efficiencies. In addition, a holistic analysis of the personal vehicle design problem shows that the upper position of the seat is also the best. The results of the research can be used to optimize personal vehicles using human force as a drive.

Immediate effects of myofascial release to the pectoral fascia on posture, range of motion, and muscle excitation: a crossover randomized clinical trial.

CONTEXT: Forward shoulder posture (FSP) is a risk factor for shoulder pathology. Manual therapists often use myofascial release (MFR) to elongate restricted pectoral fascia to reduce FSP and improve shoulder function; however, the effects of this treatment approach remain anecdotal. OBJECTIVE: Determine the acute effects of 4-min of MFR, compared to a soft-touch control (CON), to the pectoral fascia on: 1) FSP, 2) shoulder horizontal abduction ROM (HA-ROM), and 3) muscle excitation of the trapezius (upper, middle, lower [UT, MT, LT]) and pectoralis major (PEC). METHODS: Fifty-nine right-handed participants (27 ± 9 years, 30 female) with FSP, but otherwise asymptomatic shoulders participated in a randomized crossover clinical trial by attending two experimental sessions: one MFR and one CON treatment, each administered by a Registered Massage Therapist. FSP, HA-ROM, and muscle excitation during a reaching task, were measured before and after each treatment. RESULTS: There was a significant interaction between treatment and time for FSP (p = .018, ηp = .093) with FSP decreasing from PRE MFR (128 ± 19 mm) to POST MFR (123 ± 19 mm; p < .001, ηp = .420) and PRE CON (126 ± 19 mm) to POST CON (124 ± 18 mm; p < .001, ηp = .191) interventions. There were no significant differences in HA-ROM or muscle excitation. CONCLUSION: Four minutes of MFR or CON to the pectoral fascia acutely reduces FSP.

Effects of vibration-based biofeedback on multifidus muscle activity and pelvic tilt angle in subjects with hip flexion limitation.

BACKGROUND: Sedentary work may lead to low back pain. In particular, a slumped sitting position may exacerbate low back pain because of tissue damage caused by excessive lumbar flexion and posterior pelvic tilting. Subjects with low back pain may have excessive changes in the lumbopelvic posture and back muscle activity in the sitting position. OBJECTIVE: The purpose of this study was to compare the effects of vibration-based biofeedback using a motion sensor belt and no biofeedback on multifidus (MF) muscle activity and pelvic tilt angle during typing. METHODS: Thirty subjects with low back pain accompanied by hip flexion limitation (15 each in the biofeedback and non-biofeedback groups) were enrolled. Electromyography was used to investigate MF muscle activity before and after typing for 30 min. Pelvic tilt was measured after typing in a sitting position for 30 min. Independent t-tests were used to compare MF muscle activity, and pelvic and second sacrum tilt angles, between the biofeedback and non-biofeedback groups. RESULTS: After typing for 30 min, changes in MF muscle activity (11.45% and -7.19% for the biofeedback and nonbiofeedback groups, respectively) and pelvic and second sacrum tilt angles (3.15∘ and 4.12∘ for the biofeedback group and -11.05∘ and -18.16∘ for the non-biofeedback group, respectively) were significantly smaller in the biofeedback than non-biofeedback group (p< 0.05). CONCLUSION: Vibration-based biofeedback minimizes the reduction in MF muscle activity and changes in pelvic and second sacrum tilt angles during typing in individuals with low back pain accompanied by hip flexion limitation.

Effects of multi-gravitational suspension-based therapy on posture, physical fitness, quality of life, depression, and sleep quality in women without regular exercise habits.

BACKGROUND: Multi-gravitational suspension-based therapy (M-Gravity) is a comprehensive discipline based on the principles of non-gravity, which serves to increase the quality of life and holistic health of the individual with the rehabilitation content of non-pressure inversion therapy and suspension systems. AIMS: To examine the effects of M-Gravity exercise on posture, physical fitness, quality of life, depression, and sleep quality in women without regular exercise habits. METHODS: This study included 20 women without regular exercise habits, who participated in M-Gravity exercise and 20 women who did not participate in any exercise program. Posture was measured by the New York posture rating chart, flexibility of the hamstring and pectoral muscles were assessed with flexibility tests, and endurance of the core muscles was measured with plank test. Depression levels were measured by Beck Depression Inventory, sleep quality was measured by Pittsburgh Sleep Quality Index, and Nottingham Health Profile was used to measure the perceived health levels of the subjects. Measurement of the core stability was performed with the Stabilizer Pressure Biofeedback. Two evaluations were made at baseline and after 4 weeks of exercise program. RESULTS: Although statistically significant results were achieved for all parameters in the M-Gravity group, no differences were observed in the control group between baseline and post-test scores (p < 0.05). CONCLUSIONS: We came to the idea that eight sessions of M-Gravity program may have positive effects on posture, physical fitness and quality of life in women who do not have regular exercise habits.

Postural control in emotional states: An effect of biofeedback.

BACKGROUND: Emotional states in the short term and affective impairments, such as anxiety and depression in the long run, can have a significant impact on postural control. Individuals with these conditions often struggle with maintaining balance during emotionally charged situations, which can increase their risk of falls and injuries. Biofeedback has been proposed as a potential intervention to improve postural control during emotional induction. RESEARCH QUESTION: How do emotional stimuli affect postural control performance in the presence of real-time postural feedback? METHODS: Forty-two participants took part in the study. The visual stimuli used in the experiment to induce emotions of various valence in the subjects were video clips, containing a series of pictures (24 positive, 24 neutral and 24 negative pictures). During the experiment, participants were required to maintain balance standing on a force platform while watching the videos on a computer screen. For each subject, three sessions of 480 s were generated, each of which included two conditions: with and without biofeedback (a target on the screen indicating the subject's position relative to the center of pressure (CoP). RESULTS: The No Feedback condition provoked a higher medial-lateral and anterior-posterior sway, but lower velocity of CoP than the Feedback condition. We did not find any effect of the valence of emotional videos on indicators of postural control in No Feedback condition. However, both negative and positive videos provoked a lower velocity of CoP in comparison to neutral videos in the Feedback condition. SIGNIFICANCE: Changes observed in postural control during the Feedback condition in the presence of emotional stimuli (both negative and positive) could be explained by the shift in attention from the task of maintaining posture to the emotional videos. The results of this study have important implications for clinicians involved in postural training and rehabilitation.

Assessment of a karate performer's position estimation system without any markers.

Karate has become more popular, and researches have been conducted on training methods and motion analysis related to karate. The AR system for karate is an effective system for training and for the audience to understand the performance. To develop the AR system, it is necessary to acquire the movement of the performer. The purpose of the research is to assess a motion capture system to estimate a karate performer's full-body position and posture from HoloLens 2, without wearing any attachments. We used ThreeDPoseUnityBarracuda to estimate the position and posture of the performer's joints. In the experiment, the estimated joint's positions were compared with actual positions using the inertial three-dimensional motion capture. As results, although the error increased when the performer's movement was large, the median error between the estimated and actual positions was a maximum of 0.24 m at the x-coordinate of the right hand, and high accuracy was obtained when the performer's movement was small.

Back Pain and Body Posture Evaluation Instrument for Adults (BackPEI-A): Updating and an online application.

INTRODUCTION: Back Pain and Body Posture Evaluation Instrument for Adults (BackPEI-A) lags the most recent literature, as it does not assess issues related to activity increasingly present in the daily lives of people of all ages. PURPOSE: (1) to update the BackPEI-A by including four new questions regarding the use of mobile devices; (2) to present a new graphic design of the issues related to back and neck pain to facilitate understanding of the location of these pains; (3) to test the content validity and the reliability of the new questions; and (4) to identify whether the BackPEI-A version in online form has adequate reliability. METHODS: The content validation by evaluation of eight experts, and the reliability of the new questions and of the online version were assessed. The new questions were translated to English. Content validation was assessed by the content validity index (CVI). Reliability was assessed using the agreement percentage (%C), the kappa statistic (k), and the intraclass correlation coefficient (ICC). k > 0.4 and %C > 0.5 were assumed to include new questions. RESULTS: The new questions showed good agreement among the experts, k > 0.4 and %C > 0.5. Both forms applied presented an average kappa of total sample ranging from moderate to good, and moderate ICC values, showing an adequate reliability. CONCLUSION: The updated BackPEI-A is valid and reliable and allows the identification of aspects related to back and neck pain, as well as possible risk factors.

An IoT Sensing Platform and Serious Game for Remote Martial Arts Training.

We propose a system for self-supported martial arts training using an IoT sensing platform and Serious Game that can also be extended for general sports training. In martial arts, it is important that the practitioner is correctly performing each technique to accurately learn and prevent injury. A common stance in all martial arts, but especially in Shaolin Kung Fu, is the horse stance or Mabu. With the pandemic, many more people adopted remote training without the presence of a professional trainer to give advice. Our developed LifeMat system, which is a novel IoT pressure-sensitive training mat, uses pressure maps and pattern recognition to accurately classify key martial arts postures, provide feedback on form, and detect when the user performs the technique incorrectly. This is presented in the form of a Serious Game we have developed named Kung Future that focuses on the Mabu stance as a case study. We tested 14 participants with three different feedback conditions and demonstrated that, on average, participants had higher performance, duration, engagement, and motivation when game feedback was active. Furthermore, user responses from the surveys suggested positive feedback for real-world and long-term use and scalability.

Effects of the combination of traditional Thai massage, scapular stabilization exercise, and chest mobilization in subjects with forward head posture: a single-blinded randomized clinical trial.

BACKGROUND: Forward head posture (FHP) is a common condition where the head appears to be positioned in front of the vertical midline of the body. FHP is associated with shortening of the neck extensors and pectoral muscles, and the deep neck flexors and shoulder retractors are weakened. FHP is also found to cause decreases in respiratory function. Few clinical trials have investigated the effects of combination treatments to alleviate these problems. The aim of this study was to examine the effects of combination of traditional Thai massage, scapular stabilization exercise, and chest mobilization on forward head angle (FHA), forced vital capacity (FVC), and cervical flexion in subjects with FHP. METHODS: Forty-eight subjects with FHP were randomly allocated to a treatment group receiving a Combination of Traditional Thai massage, Scapular stabilization exercise, and Chest mobilization (CTSC group) (n = 24) and a control group (relaxed by lying supine) (n = 24). FHA, FVC, and cervical flexion were measured before and after the four-week intervention (Week 4) and one month after the intervention period (Week 8). RESULTS: The CTSC group showed statistically significantly greater improvement in FHA and cervical flexion than the control group at Week 4 (FHA, mean difference - 6.05; 95% CI - 8.03, - 4.07; cervical flexion, mean difference 6.84; 95% CI 3.14, 10.55) and Week 8 (FHA, mean difference - 4.64; 95% CI ( - 6.71, - 2.58); cervical flexion, mean difference 5.21; 95% CI 0.84, 9.58). There were no significant between-group differences in FVC at week 4 (mean difference 0.09; 95% CI - 0.06, 0.23) and week 8 (mean difference 0.04; 95% CI - 0.11, 0.19). CONCLUSION: This study showed that CTSC had a positive effect on FHA and cervical flexion in subjects with FHP. TRIAL REGISTRATION: Thai Clinical Trials Registry (TCTR) (Identification number: TCTR20211119001), registered 19 November 2021; https://www.thaiclinicaltrials.org/show/TCTR20211119001 .

Pain Reduction and Posture Alignment Improvement in Older Adults with Chronic Low Back Pain: A Novel Approach Using Spinal Thermal Massage Bed and Calf Pneumatic Cell Compression.

BACKGROUND Chronic low back pain (CLBP) significantly affects the well-being of older adults, leading to diminished quality of life and heightened stress. Existing treatments have limited effectiveness and potential side effects. This study aimed to explore an integrative approach, employing a combination of spinal thermal massage bed (STMB) and intermittent pneumatic calf compression, as an alternative strategy for managing CLBP, improving body posture, reducing stress, and enhancing quality of life. MATERIAL AND METHODS Twenty-three participants aged 65-80 years completed a 4-week intervention involving eight sessions (2 per week) with the STMB device. Outcome measures included pain level assessed by the visual analog scale, trunk and pelvic tilting angles indicating spine curvature, stress level of the autonomic nervous system, Oswestry Disability Index, and EuroQol five-dimensions QoL questionnaire. RESULTS The study revealed significant reductions in pain intensity between baseline and mid-term scores (p=0.002) and between baseline and post-test scores (p=0.001). Moreover, notable improvements were observed in trunk and pelvic tilting angles (p<0.001) and stress scores between baseline and mid-term scores (p=0.037) and between baseline and post-test scores (p=0.019). However, no significant changes were observed in disability level or QoL. Participants expressed high satisfaction with the intervention, and no serious side effects were reported CONCLUSIONS This study provides compelling evidence supporting the safety and efficacy of combining STMB with intermittent pneumatic calf compression in reducing pain intensity and stress levels and improving trunk and pelvic tilting angles. Clinical trial number: KCT0008212.

Three-month work-related musculoskeletal disorders assessment during manual lymphatic drainage in physiotherapists using Generic Postures notion.

OBJECTIVES: The aim of this work was to quantify the postures and to assess the musculoskeletal disorders (MSDs) risk in physiotherapists repeating a manual lymphatic drainage (MLD) over a three-month period. The underlying hypothesis was that there would be Generic Postures (GP) that would be repeated and could be used to more simply describe repetitive and long-duration complex activities. METHODS: The posture of five physiotherapists performing five 20-min MLD at their workplace was captured by two cameras. From the recordings, the adopted postures were extracted every 5 s and quantified through 13 joint angles, that is, 6594 analyzed postures. Rapid Upper Limb (RULA) and Rapid Entire Body Assessment (REBA) were used to assess MSDs risks. A hierarchical analysis was used to define GP. RESULTS: Seven GP were identified through mean values and standard deviation. GP ergonomic assessment showed a low to moderate MSD risk (RULA between 3 and 6 and REBA between 2 and 7). High neck (>20°) and trunk (>15°) flexion were observed for all GP. High shoulder abduction and flexion (>40°) were evidenced for GP3 to GP5. GP1 was the most used (34%) and presented the lowest ergonomic scores (RULA: 4.46 ± 0.84; REBA: 5.06 ± 1.75). GP3 to GP6 had frequency of between 10 and 20%. GP5, GP6, and GP7 obtained the highest ergonomic scores (RULA>5; REBA>7). All physiotherapists use different GP combinations to perform MLD. CONCLUSION: MLD could be described as a combination of GP. Ergonomic analysis showed that MLD exposes physiotherapists to low at moderate MSD risks.

Measuring transversus abdominis activity using pressure biofeedback unit-A technical report.

BACKGROUND AND PURPOSE: Pressure biofeedback is a tool that can detect the movement of a structure and may be used as an indicator of muscle function. It's widely used to measure the transversus abdominis (TrA) muscle activity. Pressure biofeedback (PBU) monitors the abdominal wall movement by measuring the pressure change during abdominal hollowing and can indirectly evaluate the TrA muscle function, which is considered as a valuable tool. The evaluation of the training of core muscles, including the transversus abdominis, requires a reliable outcome. Various methods using different positions are used to evaluate the transversus abdominis muscle function. However, it is noted that a standard way of evaluation and training still needs to be improved in research and clinical practice. This technical report discusses the optimal position and technique to measure the TrA muscle activity using PBU, with discussions on the merits and demerits of the body positions. METHODS: The technical report is presented with a literature review of the PBU measurement of TrA and through observation in the clinical practice. The evaluation methods of TrA, including the position to activate and isolate, are discussed in detail. RESULTS: Training core muscles does not imply TrA activation, and evaluating isolated TrA and multifidus is essential before intervention. The abdominal drawing-in maneuver effectively activates TrA in various evaluation positions of the body, but when using PBUs, it would be valid in a prone position. DISCUSSION: Different body positions are practiced to train TrA and core muscles using PBU, commonly adopted by practice are in supine. It's noted that most of the studies lack in establishing the effectiveness of the position in evaluating the TrA muscle activity using PBU. The need for insight into an appropriate technique for evaluating TrA activity is addressed in this technical report. This report presents key points on the complete technique and concludes that the prone position is superior to other positions and recommended for measuring and recording the TrA activity using a PBU.

Effects of a biomechanical-based Tai Chi program on gait and posture in people with Parkinson's disease: study protocol for a randomized controlled trial.

BACKGROUND: Parkinson's disease (PD) is associated with changes in gait and posture, which increases the rate of falls and injuries in this population. Tai Chi (TC) training enhances the movement capacity of patients with PD. However, the understanding of the effect of TC training on gait and postural stability in PD is lacking. This study aims to examine the effect of biomechanical-based TC training on dynamic postural stability and its relationship with walking performance. METHODS/DESIGN: A single-blind, randomized control trial of 40 individuals with early-stage PD was conducted (Hoehn and Yahr stages 1 to 3). Patients with PD will be randomly assigned to either the TC or control group. The TC group will participate in a biomechanical-based TC training program that is formed based on the movement analysis of TC and will be practiced thrice a week for 12 weeks. The control group will be required to engage in at least 60 min of regular physical activity (PA) on their own for three times per week for 12 weeks. The primary and secondary outcomes will be assessed at baseline and at 6 and 12 weeks after commencing the study protocol. The primary outcome measures will include dynamic postural stability indicated by the center of mass and center of pressure separation distance and clearance distance of the heel and toe measured during fixed-obstacle crossing. The secondary measures are gait speed, cadence, step length during level surface walking (simple task), and fixed-obstacle crossing (challenging task). The Unified Parkinson's Disease Rating Scale, single leg-stance test with eyes open and closed, and three cognitive scores (Stroop Test, Trail Making Test Part B, and the Wisconsin Card Sorting Test) were also employed. DISCUSSION: This protocol could lead to the development of a biomechanics TC training program for the improvement of gait and postural stability among individuals with PD. The program could enhance the understanding of the effect of TC training on gait and postural stability and could help improve or preserve the postural stability, self-confidence, and active participation in social activities of the participants, thus enhancing their overall quality of life. TRIAL REGISTRATION: ClinicalTrials.gov NCT04644367. Registered on 25 November 2020.

Knee joint repositioning error in different trunk positions among females with chronic nonspecific low back pain: A cross-sectional study.

PURPOSE: Proprioception is a self-perceived sense of position and movement of one's body and its deficits can lead to motor control problems such as delayed muscle reflexes. Previous studies have confirmed lumbar proprioception impairments among individuals with Low Back Pain (LBP), which can afflict the normal central sensory-motor control and hence increases the risk of abnormal loading on the lumbar spine. Although the local investigation of proprioception is important, its influence on other joints in a kinetic chain particularly between extremities and spine should not be ignored. Therefore, the aim of this study was to compare the proprioception of knee joint in different trunk positions among females with chronic nonspecific low back pain (CNSLBP) and healthy females. DESIGN: The study included 24 healthy subjects and 25 patients with CNSLBP participated in this study. Repositioning error of knee joint in four different lumbar positions including flexion, neutral position, 50% ROM of left rotation and 50% ROM right rotation was evaluated using an inclinometer. Absolute error and constant error were obtained and analyzed. RESULTS: Absolute error in flexion and neutral positions in the individuals with CNSLBP were significantly higher than in healthy individuals; whereas, there was no significant difference in absolute and constant error between the two groups in 50% rotation to either side. CONCLUSION: This study showed that knee joint repositioning accuracy was reduced in patients with CNSLBP compared to healthy ones.

Could kyphotic posture disturb body balance in young healthy population?

BACKGROUND: Kyphosis is roughly a slight forward curvature of the spine. A slight kyphosis or posterior curvature is normal throughout the human body and is present in every individual. Hyperkyphotic is a kyphotic angle greater than 40° commonly measured on a lateral X-ray measured by the Cobb method between C7 and T12. Postural instability and loss of balance can result from shifting the center of mass beyond the support base's limits. Studies are showing that kyphotic posture affects the center of gravity and affects falls in the elderly, but there are limited studies on the effect of balance in young individuals. OBJECTIVES: the correlation between the balance and thoracic kyphosis angle has been investigated. METHODS: Forty-three healthy individuals over the age of 18 participated in the study. Participants who met the criteria were split into two groups based on their kyphosis angle. For measuring thoracic kyphosis, Flexi Curve is used. Objective evaluation of static balance was made with NeuroCom Balance Manager® static posturography device. RESULTS: In terms of mean difference, there was no significant difference between the kyphotic and control groups in the balance measures, and there was no correlation between the kyphosis angle and balance measures, according to statistical analysis. CONCLUSION: According to our study, no significant relationship was found between body balance and thoracic kyphosis in the young population.

Physical Work Demands of Maintenance Workers on Onshore Petroleum Facilities in Norway: An Observational Study Utilizing Wearable Sensor Technology.

OBJECTIVES: High physical work demands can cause musculoskeletal disorders and sick leave in petroleum workers. However, our knowledge of their physical work demands is scarce and based on self-report. The objective of our study is to work towards closing this knowledge gap by assessing the physical work demands of onshore petroleum maintenance workers using body-worn sensors. METHODS: A total of 46 of 69 eligible maintenance workers (37 mechanics and 9 process technicians) from three onshore petroleum facilities in Norway filled in a questionnaire and diary and wore five accelerometers and a heart rate sensor for up to six consecutive workdays. Work-related physical activity and postures were classified using rule-based modelling in a modified version of the validated Acti4 software. RESULTS: The onshore maintenance petroleum workers were working an average of 10 h a day and spent on average this time with 48% (SD = 16.5) sitting, 1% (SD = 2.8) lying down, 39% (SD = 16.2) in light physical activity, and 9% (SD = 3.8) in moderate to vigorous physical activity. During work hours while at feet, we found arm elevation ≥60° to be 11% (SD = 7.1) (68 min), and forward bending of the trunk ≥60° to be 2% (SD = 2.2) (14 min). The workers spent 2% (SD = 2.5) (12 minu) of the workhours kneeling. We observed a high inter-individual variation for all these work exposures. Moreover, 26% (12) of the workers conducted static standing for >30% of the workday, and 17% (8) spent more than half of the work hours >33% of their estimated maximal cardiovascular capacity. CONCLUSIONS: While onshore maintenance petroleum workers on average spend about half of the workday sitting or lying down, the remaining worktime is spent with a rather high duration of arm elevation and forward bending. Quite high fraction of the workers spends much of the workhours in static standing and kneeling. We see a substantial variation in these work exposures between the workers. The findings indicate a need for preventive measures in how work is organized and performed.

Postactivation Potentiation for Muay Thai Kicking Performance.

ABSTRACT: Brown, L, Doyle, G, Bruce-Low, S, Domingos, S, Anthony, K, Rowan, F, and Galbraith, A. Postactivation potentiation for Muay Thai kicking performance. J Strength Cond Res 37(10): 2032-2037, 2023-The purpose of this study was to investigate the effects of postactivation potentiation (PAP) on Muay Thai kicking performance based on 3 different rest intervals. Aiming to quantify and indicate timing protocols for conditioning coaches when training athletes using PAP. 17 male (25.3 ± 3.6 years old; 179.3 ± 2.3 cm; 78.0 ± 5.2 kg), experienced Muay Thai fighters completed a standardized warm-up, including a 10-minute cycle on the Wattbike at 60 watts and 30 body mass squats for a dynamic stretch. Subjects then completed a baseline test by striking a PowerKube using the roundhouse and Teep kick techniques. PAP exercise consisted of 4 squat repetitions to maximum effort, followed by a rest period of 2, 5, or 8 minutes. Subjects then struck the PowerKube again using the roundhouse and Teep kick techniques. Rest periods were presented in a randomized order on separate days, with 72 hours between conditions. The level of significance was set at α = 0.05. Significant increases in both roundhouse (χ 2 (3) = 38.51, p < 0.05) and Teep kick (χ 2 (3) = 26.33, p < 0.05) striking power were observed when compared with baseline. For the roundhouse kick, significant differences and large effect sizes were present between all conditions except baseline and 2-minute rest. For the Teep kick, significant differences and large effect sizes were present between baseline and 5-minute rest and baseline and 8-minute rest. This indicates that PAP with 5- or 8-minute rest increased roundhouse and Teep kick power. This research reports that a PAP stimulus from a 4RM squat exercise, followed by a 5- or 8-minute rest period, enhances kick power in trained Muay Thai fighters. This technique provides a readily available, time-efficient method to enhance performance that can be built into the warm-up procedure of athletes before training or competition.

Articulation posture influences pitch during singing imagery.

Facial muscle activity contributes to singing and to articulation: in articulation, mouth shape can alter vowel identity; and in singing, facial movement correlates with pitch changes. Here, we examine whether mouth posture causally influences pitch during singing imagery. Based on perception-action theories and embodied cognition theories, we predict that mouth posture influences pitch judgments even when no overt utterances are produced. In two experiments (total N = 160), mouth posture was manipulated to resemble the articulation of either /i/ (as in English meet; retracted lips) or /o/ (as in French rose; protruded lips). Holding this mouth posture, participants were instructed to mentally "sing" given songs (which were all positive in valence) while listening with their inner ear and, afterwards, to assess the pitch of their mental chant. As predicted, compared to the o-posture, the i-posture led to higher pitch in mental singing. Thus, bodily states can shape experiential qualities, such as pitch, during imagery. This extends embodied music cognition and demonstrates a new link between language and music.