Intraoperative active and passive breaks during minimally invasive surgery influence upper extremity physical strain and physical stress response-A controlled, randomized cross-over, laboratory trial.

OBJECTIVE: Investigate the effect of passive, active or no intra-operative work breaks on static, median and peak muscular activity, muscular fatigue, upper body postures, heart rate, and heart rate variability. BACKGROUND: Although laparoscopic surgery is preferred over open surgery for the benefit of the patient, it puts the surgeons at higher risk for developing musculoskeletal disorders especially due to the less dynamic and awkward working posture. The organizational intervention intraoperative work break is a workplace strategy that has previously demonstrated positive effects in small-scale intervention studies. METHODS: Twenty-one surgeons were exposed to three 90-min conditions: no breaks, 2.5-min passive (standing rest) or active (targeted stretching and mobilization exercises) breaks after 30-min work blocks. Muscular activity and fatigue of back, shoulder and forearm muscles were assessed by surface electromyography; upper body posture, i.e., spinal curvature, by inclination sensors; and heart rate and variability (HRV) by electrocardiography. Generalized estimating equations were used for statistical analyses. This study (NCT03715816) was conducted from March 2019 to October 2020. RESULTS: The HRV-metric SDNN tended to be higher, but not statistically significantly, in the intervention conditions compared to the control condition. No statistically significant effects of both interventions were detected for muscular activity, joint angles or heart rate. CONCLUSION: Intraoperative work breaks, whether passive or active, may counteract shoulder muscular fatigue and increase heart rate variability. This tendency may play a role in a reduced risk for developing work-related musculoskeletal disorders and acute physical stress responses.

Musculoskeletal demands in microsurgery-an explorative study comparing the ergonomics of microscope and 3D exoscope.

To assess neurosurgeons' physical demands and investigate ergonomic aspects when using microsurgical visualization devices. Six neurosurgeons performed micro-surgical procedures on cadaveric specimens using the prototype of a digital 3D exoscope system (Aeos®, Aesculap, Tuttlingen, Germany) and a standard operating microscope (Pentero 900, Zeiss, Oberkochen, Germany) at two different patient positions (semisitting (SS), supine (SP)). The activities of the bilateral upper trapezius (UTM), anterior deltoid (ADM), and lumbar erector spinae (LEM) muscles were recorded using bipolar surface electromyography and neck flexion, arm abduction, and arm anteversion angles by gravimetrical posture sensors. Perceived discomfort frequency was assessed and subjects compared the two systems in terms of usability, posture, physical and mental demands, and working precision. Using the exoscope led to reduced ADM activity and increased UTM and LEM activity during SS position. The neck was extended when using the exoscope system with lower arm anteversion and abduction angles during the SS position. Subjects reported discomfort at the shoulder-neck area less frequently and lower physical demands when using the Aeos®. However, mental demands were slightly higher and two subjects reported lower working precision. The exoscope system has the potential to reduce the activity of the ADM by changing surgeons arm posture which may be accompanied by less discomfort in the shoulder-neck area. However, dependent on the applied patient position higher muscle activities could occur in the UTM and LEM.

Save our surgeons (SOS) - an explorative comparison of surgeons' muscular and cardiovascular demands, posture, perceived workload and discomfort during robotic vs. laparoscopic surgery.

PURPOSE: Conventional laparoscopic surgery (CLS) imposes an increased risk of work-related musculoskeletal disorders. Technical innovations, such as robotic-assisted laparoscopic surgery (RALS), may provide ergonomic benefits. We compare the surgeon`s work-related demands of CLS vs RALS for benign hysterectomies. METHODS: Five specialists (3 females, 2 males) each performed four RALS and four CLS as part of their daily clinical routine. During the surgical procedures, muscular demands were assessed by bipolar surface electromyograms of the descendent trapezius, extensor digitorum and flexor carpi radialis muscles as well as cardio-vascular demands by electrocardiography, and neck, arm and torso posture by gravimetrical position sensors. Additionally, the subjects rated their level of perceived workload (NASA TLX questionnaire with 6 dimension) and musculoskeletal discomfort (11-point Likert-scale, 0-10). RESULTS: Muscular demands of the trapezius and flexor carpi radialis muscles were lower with RALS but extensor digitorum demands increased. Cardiovascular demands were about 9 heart beats per minute (bpm) lower for RALS compared to CLS with a rather low median level for both surgical techniques (RALS = 84 bpm; CLS 90 bpm). The posture changed in RALS with an increase in neck and torso flexion, and a reduction in abduction and anteversion position of the right arm. The perceived workload was lower in the physical demands dimension but higher in the mental demands dimension during RALS. Subjective musculoskeletal discomfort was rare during both surgical techniques. CONCLUSIONS: This explorative study identified several potential ergonomic benefits related to RALS which now can be verified by studies using hypothesis testing designs. However, potential effects on muscular demands in the lower arm extensor muscles also have to be addressed in such studies.

Wrist Extensor Muscle Fatigue During a Dual Task With Two Muscular and Cognitive Load Levels in Younger and Older Adults.

OBJECTIVE: To examine the effect of concurrent physical and cognitive demands as well as age on indicators of muscle fatigue at the wrist. BACKGROUND: There are few studies examining risk indicators for musculoskeletal disorders associated with work-related physical and cognitive demands that often occur simultaneously in the workplace. METHODS: Twenty-four gender-balanced older and 24 gender-balanced younger (mean age 60 and 23 years) participants performed four 30 min dual tasks. Tasks differed by the muscular load level during force tracking: 5% and 10% of maximum voluntary contraction force (MVC) and concurrent cognitive demands on the working memory: easy and difficult. Muscle fatigue was assessed by MVC decline and changes in surface electromyography (increased root mean square: RMS, decreased median frequency: MF) at the extensor digitorum (ED) and extensor carpi ulnaris (EU). RESULTS: A decline in MVC was found in all participants when tracking was performed at 10% MVC (mean ± SD: 137.9 ± 49.2 - 123.0 ± 45.3 N). Irrespective of age, muscular, or cognitive load, RMS increased (ED 12.3 ± 6.5 - 14.1 ± 7.0% MVE, EU 15.4 ± 7.6 - 16.9 ± 8.6% MVE) and MF decreased (ED 85.4 ± 13.6 - 83.2 ± 12.8 Hz, EU 107.2 ± 17.1 - 104.3 ± 16.7 Hz) in both muscles. However, changes in MF of EU tended to be more pronounced in the older group at higher cognitive and lower muscular load, without reaching statistical significance. CONCLUSION: Maximum voluntary contraction indicated no interaction between muscle fatigue, cognitive load, or age. However, the tendencies toward altered muscle activity due to an increase in cognitive load and older age suggest muscular adaptations while maintaining tracking performance during the onset of fatigue signs in the sEMG signal. APPLICATION: If the tendencies in muscle activity are confirmed by further studies, ergonomic assessments in industrial workplaces should consider cognitive load and age when describing the risk of musculoskeletal disorders.

Using a Back Exoskeleton During Industrial and Functional Tasks-Effects on Muscle Activity, Posture, Performance, Usability, and Wearer Discomfort in a Laboratory Trial.

OBJECTIVE: To investigate the effect of using a passive back-support exoskeleton (Laevo V2.56) on muscle activity, posture, heart rate, performance, usability, and wearer comfort during a course of three industrial tasks (COU; exoskeleton worn, turned-on), stair climbing test (SCT; exoskeleton worn, turned-off), timed-up-and-go test (TUG; exoskeleton worn, turned-off) compared to no exoskeleton. BACKGROUND: Back-support exoskeletons have the potential to reduce work-related physical demands. METHODS: Thirty-six men participated. Activity of erector spinae (ES), biceps femoris (BF), rectus abdominis (RA), vastus lateralis (VL), gastrocnemius medialis (GM), trapezius descendens (TD) was recorded by electromyography; posture by trunk, hip, knee flexion angles; heart rate by electrocardiography; performance by time-to-task accomplishment (s) and perceived task difficulty (100-mm visual analogue scale; VAS); usability by the System Usability Scale (SUS) and all items belonging to domains skepticism and user-friendliness of the Technology Usage Inventory; wearer comfort by the 100-mm VAS. RESULTS: During parts of COU, using the exoskeleton decreased ES and BF activity and trunk flexion, and increased RA, GM, and TD activity, knee and hip flexion. Wearing the exoskeleton increased time-to-task accomplishment of SCT, TUG, and COU and perceived difficulty of SCT and TUG. Average SUS was 75.4, skepticism 11.5/28.0, user-friendliness 18.0/21.0, wearer comfort 31.1 mm. CONCLUSION: Using the exoskeleton modified muscle activity and posture depending on the task applied, slightly impaired performance, and was evaluated mildly uncomfortable. APPLICATION: These outcomes require investigating the effects of this passive back-supporting exoskeleton in longitudinal studies with longer operating times, providing better insights for guiding their application in real work settings.

Postural Control When Using an Industrial Lower Limb Exoskeleton: Impact of Reaching for a Working Tool and External Perturbation.

OBJECTIVE: To investigate postural control related to a lower limb exoskeleton (Chairless Chair) when (a) reaching for a working tool, and (b) an external perturbation occurs. BACKGROUND: Lower limb exoskeletons aiming to reduce physical load associated with prolonged standing may impair workers' postural control and increase the risk of falling. METHOD: Forty-five males were reaching for an object (3-kg dumbbell) at the lateral end of their reaching area without the exoskeleton in upright standing (STAND) and with the exoskeleton at a high (EXOHIGH.SEAT) and low sitting position (EXOLOW.SEAT). The task was performed with the object placed in three different angles (120°, 150°, and 180°) in the transversal plane. The minimum absolute static postural stability (SSABS.MIN) as the shortest distance (mm) of the center of pressure to the base of support border was measured (zero indicates risk of falling). Additionally, eight subjects were standing without the exoskeleton or sitting on it (EXOHIGH.SEAT and EXOLOW.SEAT) while being pulled backward. The tilting moment when subjects lost their balance was assessed. RESULTS: SSABS.MIN was lower when using the exoskeleton (p < .05) but still about 17 mm. The location of the object to be reached had no influence. Tilting moments of less than 30 nm were sufficient to let people fall backward when sitting on the exoskeleton (50 nm for STAND). CONCLUSION: Impairments in postural control by the exoskeleton may not be relevant when reaching laterally for objects up to 3 kg. When an external perturbation occurs, the risk of falling may be much higher; irrespective of factors like uneven or slippery flooring. APPLICATION: The risk of falling using the exoskeleton seems to be low when reaching laterally for an object of up to 3 kg. In situations where, for example, a collision with coworkers is likely, this exoskeleton is not recommended.

Using a Passive Back Exoskeleton During a Simulated Sorting Task: Influence on Muscle Activity, Posture, and Heart Rate.

OBJECTIVE: To evaluate using a back exoskeleton in a simulated sorting task in a static forward bent trunk posture on muscle activity, posture, and heart rate (HR). BACKGROUND: Potentials of exoskeletons for reducing musculoskeletal demands in work tasks need to be clarified. METHODS: Thirty-six healthy males performed the sorting task in 40°-forward bent static trunk posture for 90 seconds, in three trunk orientations, with and without exoskeleton. Muscle activity of the erector spinae (ES), biceps femoris (BF), trapezius descendens (TD), rectus abdominis (RA), vastus laterals (VL), and gastrocnemius medialis was recorded using surface electromyography normalized to a submaximal or maximal reference electrical activity (%RVE (reference voluntary electrical activity)/%MVE). Spine and lower limb postures were assessed by gravimetric position sensors, and HR by electrocardiography. RESULTS: Using the exoskeleton resulted in decreased BF muscle activity [-8.12%RVE], and minor changes in ES [-1.29%MVE], RA [-0.28%RVE], VL [-0.49%RVE], and TD [+1.13%RVE] muscle activity. Hip and knee flexion increased [+8.1°; +6.7°]. Heart rate decreased by 2.1 bpm. Trunk orientation had an influence on BF muscle activity. CONCLUSION: Using the back exoskeleton in a short sorting task with static trunk posture mainly reduced hip extensor muscle activity and changed lower limb but not spine posture. Implications of using a back exoskeleton for workers' musculoskeletal health need further clarification. APPLICATION: The detected changes by using the Laevo® illustrate the need for further investigation prior to practical recommendations of using exoskeletons in the field. Investigating various work scenarios in different kind of workers and long-term applications would be important elements.

Physiological changes during prolonged standing and walking considering age, gender and standing work experience.

Occupational standing is associated with musculoskeletal and venous disorders. The aim was to investigate whether lower leg oedema and muscle fatigue development differ between standing and walking and whether age, gender and standing work habituation are factors to consider. Sixty participants (15 young females, 15 young males, 15 older males, and 15 young males habituated to standing work) were included and required to stand/walk for 4.5 hours in three periods with two seated breaks. Waterplethysmography/bioelectrical impedance, muscle twitch force and surface electromyography were used to assess lower leg swelling (LLS) and muscle fatigue as well as gastrocnemius muscle activity, respectively. While standing led to LLS and muscle fatigue, walking did not. Low-level medial gastrocnemius activity was not continuous during standing. No significant influence of age, gender and standing habituation was observed. Walking can be an effective prevention measure to counteract the detrimental effects of quasi-static standing.Practitioner summary: Prolonged standing leads to lower leg oedema and muscle fatigue while walking does not. The primary cause of fatigue may be in other muscles than the medial gastrocnemius. Walking may be an effective prevention measure for health risks of occupational standing when included intermittently.Abbreviation: BI: bioelectrical impedance; LLS: lower leg swelling; SEMG: surface electromyography; MTF: muscle twitch force; WP: waterplethysmography; Bsl: Baseline; L: Lunch; E: Evening; MTM: method times measurement; EA: electrical activity; IQR: interquartile range; p: percentile; M: mean; SE: standard error; Adj: adjusted.

Work-break schedules for preventing musculoskeletal symptoms and disorders in healthy workers.

BACKGROUND: Work-related musculoskeletal disorders are a group of musculoskeletal disorders that comprise one of the most common disorders related to occupational sick leave worldwide. Musculoskeletal disorders accounted for 21% to 28% of work absenteeism days in 2017/2018 in the Netherlands, Germany and the UK. There are several interventions that may be effective in tackling the high prevalence of work-related musculoskeletal disorders among workers, such as physical, cognitive and organisational interventions. In this review, we will focus on work breaks as a measure of primary prevention, which are a type of organisational intervention. OBJECTIVES: To compare the effectiveness of different work-break schedules for preventing work-related musculoskeletal symptoms and disorders in healthy workers, when compared to conventional or alternate work-break schedules. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, PsycINFO, SCOPUS, Web of Science, ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform, to April/May 2019. In addition, we searched references of the included studies and of relevant literature reviews. SELECTION CRITERIA: We included randomised controlled trials (RCTs) of work-break interventions for preventing work-related musculoskeletal symptoms and disorders among workers. The studies were eligible for inclusion when intervening on work-break frequency, duration and/or type, compared to conventional or an alternate work-break intervention. We included only those studies in which the investigated population included healthy, adult workers, who were free of musculoskeletal complaints during study enrolment, without restrictions to sex or occupation. The primary outcomes were newly diagnosed musculoskeletal disorders, self-reported musculoskeletal pain, discomfort or fatigue, and productivity or work performance. We considered workload changes as secondary outcomes. DATA COLLECTION AND ANALYSIS: Two review authors independently screened titles, abstracts and full texts for study eligibility, extracted data and assessed risk of bias. We contacted authors for additional study data where required. We performed meta-analyses, where possible, and we assessed the overall quality of the evidence for each outcome of each comparison using the five GRADE considerations. MAIN RESULTS: We included six studies (373 workers), four parallel RCTs, one cross-over RCT, and one combined parallel plus cross-over RCT. At least 295 of the employees were female and at least 39 male; for the remaining 39 employees, the sex was not specified in the study trial. The studies investigated different work-break frequencies (five studies) and different work-break types (two studies). None of the studies investigated different work-break durations. We judged all studies to have a high risk of bias. The quality of the evidence for the primary outcomes of self-reported musculoskeletal pain, discomfort and fatigue was low; the quality of the evidence for the primary outcomes of productivity and work performance was very low. The studies were executed in Europe or Northern America, with none from low- to middle-income countries. One study could not be included in the data analyses, because no detailed results have been reported.Changes in the frequency of work breaksThere is low-quality evidence that additional work breaks may not have a considerable effect on musculoskeletal pain, discomfort or fatigue, when compared with no additional work breaks (standardised mean difference (SMD) -0.08; 95% CI -0.35 to 0.18; three studies; 225 participants). Additional breaks may not have a positive effect on productivity or work performance, when compared with no additional work breaks (SMD -0.07; 95% CI -0.33 to 0.19; three studies; 225 participants; very low-quality evidence).We found low-quality evidence that additional work breaks may not have a considerable effect on participant-reported musculoskeletal pain, discomfort or fatigue (MD 1.80 on a 100-mm VAS scale; 95% CI -41.07 to 64.37; one study; 15 participants), when compared to work breaks as needed (i.e. microbreaks taken at own discretion). There is very low-quality evidence that additional work breaks may have a positive effect on productivity or work performance, when compared to work breaks as needed (MD 542.5 number of words typed per 3-hour recording session; 95% CI 177.22 to 907.78; one study; 15 participants).Additional higher frequency work breaks may not have a considerable effect on participant-reported musculoskeletal pain, discomfort or fatigue (MD 11.65 on a 100-mm VAS scale; 95% CI -41.07 to 64.37; one study; 10 participants; low-quality evidence), when compared to additional lower frequency work breaks. We found very low-quality evidence that additional higher frequency work breaks may not have a considerable effect on productivity or work performance (MD -83.00 number of words typed per 3-hour recording session; 95% CI -305.27 to 139.27; one study; 10 participants), when compared to additional lower frequency work breaks.Changes in the duration of work breaksNo trials were identified that assessed the effect of different durations of work breaks.Changes in the type of work breakWe found low-quality evidence that active breaks may not have a considerable positive effect on participant-reported musculoskeletal pain, discomfort and fatigue (MD -0.17 on a 1-7 NRS scale; 95% CI -0.71 to 0.37; one study; 153 participants), when compared to passive work breaks.Relaxation work breaks may not have a considerable effect on participant-reported musculoskeletal pain, discomfort or fatigue, when compared to physical work breaks (MD 0.20 on a 1-7 NRS scale; 95% CI -0.43 to 0.82; one study; 97 participants; low-quality evidence). AUTHORS' CONCLUSIONS: We found low-quality evidence that different work-break frequencies may have no effect on participant-reported musculoskeletal pain, discomfort and fatigue. For productivity and work performance, evidence was of very low-quality that different work-break frequencies may have a positive effect. For different types of break, there may be no effect on participant-reported musculoskeletal pain, discomfort and fatigue according to low-quality evidence. Further high-quality studies are needed to determine the effectiveness of frequency, duration and type of work-break interventions among workers, if possible, with much higher sample sizes than the studies included in the current review. Furthermore, work-break interventions should be reconsidered, taking into account worker populations other than office workers, and taking into account the possibility of combining work-break intervention with other interventions such as ergonomic training or counselling, which may may possibly have an effect on musculoskeletal outcomes and work performance.

An ergonomic field study to evaluate the effects of a rotatable handle piece on muscular stress and fatigue as well as subjective ratings of usability, wrist posture and precision during laparoscopic surgery: an explorative pilot study.

PURPOSE: The interface between surgeon and the laparoscopic instrument is an important factor in biomechanical stress that may increase the risk of musculoskeletal complaints in surgeons. This article investigates the effect of a laparoscopic instrument with a rotatable handle piece (rot-HP) on muscular stress and fatigue during routine laparoscopic procedures (LP) as well as usability, wrist posture and working precision. METHODS: 40 LP (subtotal hysterectomies) performed by 11 surgeons were investigated. 20 LP were carried out with the rot-HP and 20 with a fixed (standard) laparoscopic handle piece instrument. Shoulder and arm muscle activity was monitored via surface electromyography (sEMG). The electrical activity (EA) and median power frequency (MPF) were used to determine muscular stress and fatigue. Usability, wrist posture, and working precision between handle piece conditions were assessed by a survey. RESULTS: Using the rot-HP did not reduce muscular stress. A tendency of muscular fatigue (increasing EA, decreasing MPF) occurred in the upper trapezius, middle deltoid and extensor digitorum muscles; however, no differences were found between handle pieces. Wrist posture was more comfortable using the rot-HP and working precision and usability tended to be preferred using the standard handle piece. CONCLUSIONS: Although wrist posture seemed to be optimized by the rot-HP, no effect on muscular stress and fatigue was observed in routine LP (< 60 min duration). Optimization of wrist posture may provide positive effects in mid- or long-term procedures. However, sufficient familiarization with the new instrument is crucial since working precision and usability could be impaired.

Ergonomic Benefits From a Laparoscopic Instrument With Rotatable Handle Piece Depend on the Area of the Operating Field and Working Height.

Objective To evaluate the effect of a laparoscopic instrument with a 360° rotatable handle piece (rot-HP) on biomechanical stress and precision in different areas of a simulated operating field at two working heights. Background Surgeons performing laparoscopic procedures are exposed to biomechanical stress and have an increased risk of musculoskeletal complaints. Method Fifty-seven healthy subjects (27 men, median age 26) without experience in laparoscopy performed a precision task in four quadrants (A-D) of the operating field using the rot-HP or a common fixed handle piece (fixed-HP) at an individually adjusted lower or higher working height. Biomechanical stress was assessed by surface EMG, wrist joint angles, and arm postures and precision by the number of mistakes. Results Using the rot-HP reduced muscle activity of the biceps brachii and flexor carpi radialis muscle. An interaction of flexor activity and area of the operating field occurred with the lowest activity in Quadrant C. Wrist joint angles were more neutral using the rot-HP, especially when the lower working height was applied and in Quadrants B and C. However, increased wrist dorsal flexion occurred in Quadrant A while using the rot-HP. Arm postures and precision were less affected. Conclusion The rot-HP allows some reductions of stresses in the arm and hand region, whereas the stress in the shoulder neck region is not modified. Application The instrument's position and the working height may have to be considered as mediatory factors when describing the effectiveness of an ergonomic handle design for laparoscopic instruments.

Exercise therapy in patients with hip osteoarthritis: Effect on hip muscle strength and safety aspects of exercise-results of a randomized controlled trial.

PURPOSE: To evaluate the effect of an exercise therapy concept (the Tübingen exercise therapy approach THüKo) for increasing hip muscle strength (HMS) in patients with hip osteoarthritis (OA), and to investigate whether patients do adhere to the intervention and if there are any adverse events related to the intervention. METHODS: A total of 210 hip OA patients (89 females, 121 males) were randomized into a 12-week exercise intervention (THüKo) including group sessions (1/week) and home exercising (2/week), a placebo ultrasound group (1/week) or a control group (no treatment). HMS was measured as isometric peak torque of hip abduction, adduction, flexion, and extension. Adherence to exercise and safety aspects were monitored as additional outcomes. RESULTS: Baseline adjusted post intervention HMS of the THüKo group were higher compared to the control group (differences of 0.11-0.27 Nm/kg, p < 0.01) and to the placebo ultrasound group (differences of 0.09-0.19 Nm/kg, p < 0.01). Adherence to exercise was high (about 90%). No subject had to refuse from training because of an exercise related adverse event and exercise related pain was only of intermittent nature without sustainable adverse effects. CONCLUSIONS: The Tübingen exercise therapy approach has shown to have a significant positive effect on HMS. Its implementation has shown to be feasible and safe according to the percentage of exercise participation and the absence of sustainable adverse events.

Effect of a laparoscopic instrument with rotatable handle piece on biomechanical stress during laparoscopic procedures.

OBJECTIVE: To investigate the effect of a pistol grip laparoscopic instrument with a rotatable handle piece (rot-HP) on biomechanical stress and precision as well as a possible interaction between the instrument and working height (WH). BACKGROUND: Biomechanical stress induced by laparoscopic surgery (LS) is associated with work-related upper limb musculoskeletal disorders in surgeons. Ergonomic handle designs of laparoscopic instruments may reduce the risk of musculoskeletal disorders. METHODS: Without LS experience, 57 healthy subjects (30 women; 27 men, median age: 26) were observed while performing a laparoscopic exercise. Subjects had to pick up coloured pins and place them into a colour-coded wooden set-up inside a pelvitrainer. The exercise was performed at two WHs using the rot-HP and a standard laparoscopic (fixed) handle piece in randomized sequence. Biomechanical stress was monitored via surface electromyography (sEMG) on fife muscles from the upper limb and shoulder region. Further, the wrist angle (palmar and dorsi flexion) and posture of the dominant upper arm were recorded. Precision was assessed using the number of validly placed pins and process time. RESULTS: sEMG parameters and upper arm postures indicated no differences in biomechanical stress related to either laparoscopic handle piece. The higher WH was associated with higher trapezius and deltoid activity and elevated arm postures (p < 0.05). Neutral wrist positions were more frequent using the rot-HP, and the lower WH resulted in slightly more neutral wrist positions. Precision was similar during all experimental conditions. CONCLUSIONS: The rot-HP did not decrease biomechanical stress in the shoulder or lower arm muscles. However, wrist angle position may be optimized without affecting precision. Long-term effects of the rot-HP on preventing complaints of the upper extremity should be evaluated. Low WH is recommended to reduce biomechanical stress in the shoulder during laparoscopic surgery.

Effectiveness and efficiency of an 11-week exercise intervention for patients with hip or knee osteoarthritis: a protocol for a controlled study in the context of health services research.

BACKGROUND: Osteoarthritis is the most common reason for pain in older adults, and the individual and economic burden of this disease is immense. The chronic character of osteoarthritis requires a long-term therapeutic treatment. In this regard life-style interventions such as physical exercises that can be carried out by the patient himself are recommended as first line treatment. There is evidence for the short-term benefit of exercise therapy in terms of pain reduction and physical functioning. Nonetheless research agendas highlight the need for multifaceted interventions that incorporate exercise strategies into patient care. Studies should be conducted with appropriate sample sizes and should allow statements on long-term effects as well as cost-utility and safety. These open questions are under the scope of this study. METHODS/DESIGN: This is a controlled study in the context of health services research. The study population consists of n = 1400 subjects with hip or knee osteoarthritis. The intervention group will be recruited from participants of a country-wide health insurance offer for people with hip or knee osteoarthritis. Potential participants for the control group (ratio 10:1 (control vs. intervention) will be filtered out from the insurance data base according to pre-defined matching criteria and asked by letter for their participation. The final statistical twins from the responders (1:1) will be determined via propensity score matching. The progressive training intervention comprises 8 supervised group sessions, supplemented by home exercises (2/week over 11 weeks). Exercises include mobilization, strengthening and training of postural control. Primary outcomes are pain and function measured with the WOMAC Index immediately after the intervention period. Among other things, health related quality of life, self-efficacy, cost utility and safety will be evaluated as secondary outcomes. Participants will be followed up 6, 12 and 24 month after baseline. DISCUSSION: Results of this trial will document the effects of clinical as well as economic outcomes in a regular health care setting on the basis of a large sample size. As such, results of this trial might have great impact on future implementations of group- and home-based exercises in hip or knee osteoarthritis. TRAIL REGISTRATION: German Clinical Trial Register DRKS00009251 . Registered 10 September 2015.

Long-Lasting Changes in Muscle Twitch Force During Simulated Work While Standing or Walking.

OBJECTIVE: The aim of this study was to evaluate the long-lasting effects of prolonged standing work on a hard floor or floor mat and slow-pace walking on muscle twitch force (MTF) elicited by electrical stimulation. BACKGROUND: Prolonged standing work may alter lower-leg muscle function, which can be quantified by changes in the MTF amplitude and duration related to muscle fatigue. Ergonomic interventions have been proposed to mitigate fatigue and discomfort; however, their influences remain controversial. METHOD: Ten men and eight women simulated standing work in 320-min experiments with three conditions: standing on a hard floor or an antifatigue mat and walking on a treadmill, each including three seated rest breaks. MTF in the gastrocnemius-soleus muscles was evaluated through changes in signal amplitude and duration. RESULTS: The significant decrease of MTF amplitude and an increase of duration after standing work on a hard floor and on a mat persisted beyond 1 hr postwork. During walking, significant MTF metrics changes appeared 30 min postwork. MTF amplitude decrease was not significant after the first 110 min in any of the conditions; however, MTF duration was significantly higher than baseline in the standing conditions. CONCLUSION: Similar long-lasting weakening of MTF was induced by standing on a hard floor and on an antifatigue mat. However, walking partially attenuated this phenomenon. APPLICATION: Mostly static standing is likely to contribute to alterations of MTF in lower-leg muscles and potentially to musculoskeletal disorders regardless of the flooring characteristics. Occupational activities including slow-pace walking may reduce such deterioration in muscle function.

Development of an arm support system to improve ergonomics in laparoscopic surgery: study design and provisional results.

BACKGROUND: Laparoscopic surgery (LS) induces physical stress to the surgeon that is associated with an increased prevalence of musculoskeletal pain and injury in the shoulder-neck region. The aim of this research project is to develop an arm support system (ASsyst) that reduces physical stress and is applicable to various laparoscopic interventions and operation room settings. METHODS: A systematic approach to develop an ASsyst started in October 2012 consisting of five consecutive steps. In step 1, 14 laparoscopic interventions were observed using subjective and objective measures to determine key indicators for the conception of an ASsyst in LS. In step 2, an expert workshop was held to find and evaluate solutions to generate concepts for a support system based on the results of step 1 and general methods. During the third step, prototypes of ASsyst were tested in an experimental setting. Steps 4 and 5 are currently in process and include the final development of the ASsyst using the most promising concept for the evaluation during simulated LS. RESULTS: Increased levels of physical stress were found in LS. Asymmetric strains were common. Three prototypes of ASsyst emerged from step 1 and 2. These prototypes were a cable construction with a noose for the lower arm, a support from below the elbow and a pneumatic vest supporting the upper arm. The experimental testing of these prototypes demonstrated reduced physical stress when compared to the unsupported environment. The support from below the elbow seemed to be the most practical in terms of implementation in various operation room settings and acceptance by surgeons. Step 4 and 5 are still in process. CONCLUSIONS: Ergonomic problems have been identified in LS that could be addressed by an ASsyst. The concept of supporting the elbow from below has been found to be the most promising approach.

Influence of Intraoperative Active and Passive Breaks in Simulated Minimally Invasive Procedures on Surgeons' Perceived Discomfort, Performance, and Workload.

Laparoscopic surgeons are at high risk of experiencing musculoskeletal discomfort, which is considered the result of long-lasting static and awkward body postures. We primarily aimed to evaluate whether passive and active work breaks can reduce ratings of perceived discomfort among laparoscopic surgeons compared with no work breaks. We secondarily aimed to examine potential differences in performance and workload across work break conditions and requested the surgeons evaluate working with passive or active work breaks. Following a balanced, randomized cross-over design, laparoscopic surgeons performed three 90 min laparoscopic simulations without and with 2.5 min passive or active work breaks after 30 min work blocks on separate days. The simulation included the following tasks: a hot wire, peg transfer, pick-and-place, pick-and-tighten, pick-and-thread, and pull-and-stick tasks. Ratings of perceived discomfort (CR10 Borg Scale), performance per subtask, and perceived workload (NASA-TLX) were recorded, and the break interventions were evaluated (self-developed questionnaire). Statistical analyses were performed on the rating of perceived discomfort and a selection of the performance outcomes. Twenty-one participants (9F) were included, with a mean age of 36.6 years (SD 9.7) and an average experience in laparoscopies of 8.5 years (SD 5.6). Ratings of perceived musculoskeletal discomfort slightly increased over time from a mean level of 0.1 to 0.9 but did not statistically significantly differ between conditions (p = 0.439). Performance outcomes of the hot wire and peg transfer tasks did not statistically significantly differ between conditions. The overall evaluation by the participants was slightly in favor regarding the duration and content of active breaks and showed a 65% likelihood of implementing them on their own initiative in ≥90 min-lasting laparoscopic surgeries, compared with passive breaks. Both passive and active breaks did not statistically significantly influence ratings of perceived discomfort or perceived workload in a 90 min simulation of laparoscopic surgery, with an overall low mean level of perceived discomfort of 0.9 (SD 1.4). As work breaks do not lead to performance losses, rest breaks should be tested in real-life situations across a complete working shift, where perceived discomfort may differ from this laboratory situation. However, in this respect, it is crucial to investigate the acceptance and practicality of intraoperative work breaks in feasibility studies in advance of assessing their effectiveness in follow-up longitudinal trials.

Motor variability during a repetitive lifting task is impaired by wearing a passive back-support exoskeleton.

PURPOSE: Evaluate whether wearing a passive back-support exoskeleton during repetitive lifting impairs motor variability of erector spinae muscle and spine movement and whether this association is influenced by lifting style. SCOPE: Thirty-six healthy males performed ten lifts in four randomized conditions with exoskeleton (without, with) and lifting style (squat, stoop) as dependent variables. One lifting cycle contained four phases: bending/straighten without/with load. Erector spinae muscular activity, thoracic kyphosis and lumbar lordosis were measured with surface electromyography and gravimetric position sensors, respectively. Absolute and relative cycle-to-cycle variability were calculated. The effects of exoskeleton and exoskeleton × lifting style were assessed on outcomes during the complete lifting cycle and its four phases. RESULTS: For the complete lifting cycle, muscular variability and thoracic kyphosis variability decreased whereas lumbar lordosis variability increased with exoskeleton. For lifting phases, effects of exoskeleton were mixed. Absolute and relative muscular variability showed a significant interaction effect for the phase straighten with load; variability decreased with exoskeleton during squat lifting. CONCLUSION: Using the exoskeleton impaired several motor variability parameters during lifting, supporting previous findings that exoskeletons may limit freedom of movement. The impact of this result on longer-term development of muscular fatigue or musculoskeletal disorders cannot yet be estimated.

Limitations in evaluating COVID-19 protective face masks using open circuit spirometry systems: respiratory measurement mask introduces bias in breathing pressure and perceived respiratory effort.

Objective.In response to the COVID-19 pandemic and the resulting widespread use of protective face masks, studies have been and are being conducted to investigate potential side effects of wearing masks on the performance and physiological parameters of wearers. The purpose of the present study is to determine whether and to what extent the use of a respiratory measurement (RM) mask-which is normally used during open-circuit spirometry-influences the results of these types of studies.Approach.34 subjects were involved in this intra-subject study with a cross-over design. Four different protective face masks, Community Mask, medical Mouth-Nose-Protection Mask, Filtering Face Piece Mask Class 2 (FFP2), and FFP2 with exhalation valve (FFP2ex), were tested at rest and during deep breathing by using or not using a RM mask (RM versus noRM). Breathing pressure inside the protective face masks was measured during inhalation and exhalation, and subjects rated breathing effort using an 11-stage Borg scale.Main results.The use of an additional RM mask-worn over the protective face masks-significantly increased inspiratory pressures under all mask conditions. The respiratory pressure rises to a level that substantially distorts the results. Expiratory pressure was also significantly increased except for the FFP2ex mask condition. The perceived respiratory effort was significantly increased by 1.0 to 2.8 steps on the Borgs scale for all mask conditions compared with noRM.Significance.We strongly recommend avoiding the use of RM masks for evaluating the effects of protective face masks on human physiology and subjective perception.

Influence of Face Masks on Physiological and Subjective Response during 130 Min of Simulated Light and Medium Physical Manual Work-An Explorative Study.

BACKGROUND: Undesirable side effects from wearing face masks during the ongoing COVID-19 pandemic continue to be discussed and pose a challenge to occupational health and safety when recommending safe application. Only few studies examined the effects of continuously wearing a face mask for more than one hour. Therefore, the influence of wearing a medical mask (MedMask) and a filtering facepiece class II respirator (FFP2) on the physiological and subjective outcomes in the course of 130 min of manual work was exploratively investigated. Physical work load and cardiorespiratory fitness levels were additionally considered as moderating factors. METHODS: Twenty-four healthy subjects (12 females) from three different cardiorespiratory fitness levels each performed 130 min of simulated manual work with light and medium physical workload using either no mask, a MedMask or FFP2. Heart rate, transcutaneous oxygen and carbon dioxide partial pressure (PtcO2, PtcCO2) as well as perceived physical exertion and respiratory effort were assessed continuously at discrete time intervals. Wearing comfort of the masks were additionally rated after the working period. RESULTS: There was no difference in time-dependent changes of physiological outcomes when using either a MedMask or a FFP2 compared to not wearing a mask. A stronger increase over time in perceived respiratory effort occurred when the face masks were worn, being more prominent for FFP2. Physical workload level and cardiorespiratory fitness level were no moderating factors and higher wearing comfort was rated for the MedMask. CONCLUSION: Our results suggest that using face masks during light and medium physical manual work does not induce detrimental side effects. Prolonged wearing episodes appeared to increase respiratory effort, but without affecting human physiology in a clinically relevant way.