Effect of applied cadence in repeated sprint cycling on muscle characteristics.

PURPOSE: This study aimed to investigate physiological responses, muscle-tendon unit properties of the quadriceps muscle, and mechanical performance after repeated sprint cycling at optimal and 70% of optimal cadence. METHODS: Twenty recreational cyclists performed as first sprint performance cycling test and during subsequent sessions two repeated sprint cycling protocols at optimal and 70% of optimal cadence, in random order. The muscle-tendon unit outcome measures on the dominant leg included muscle thickness, fascicle length (Lf), pennation angle (θp), and stiffness for the rectus femoris (RF), vastus lateralis (VL), and vastus medialis muscle (VM) at baseline, immediately after repeated sprint cycling, and 1-h post-exercise. RESULTS: The results showed an increase in muscle thickness and θp in RF, VL, and VM for both cadences from baseline to immediately after exercise. The Lf decreased in RF (both cadences), while stiffness decreased in RF, VL, and VM at optimal cadence, and in VL at 70% of optimal cadence from baseline to immediately after exercise. CONCLUSION: The present study revealed that the alterations in muscle characteristics were more marked after repeated sprint cycling at optimal cadence compared with a lower cadence most likely as a result of higher load on the muscle-tendon unit at optimal cadence.

Towards precision pain medicine for pain after cancer: the Cancer Pain Phenotyping Network multidisciplinary international guidelines for pain phenotyping using nociplastic pain criteria.

Pain after cancer remains underestimated and undertreated. Precision medicine is a recent concept that refers to the ability to classify patients into subgroups that differ in their susceptibility to, biology, or prognosis of a particular disease, or in their response to a specific treatment, and thus to tailor treatment to the individual patient characteristics. Applying this to pain after cancer, the ability to classify post-cancer pain into the three major pain phenotypes (i.e. nociceptive, neuropathic, and nociplastic pain) and tailor pain treatment accordingly, is an emerging issue. This is especially relevant because available evidence suggests that nociplastic pain is present in an important subgroup of those patients experiencing post-cancer pain. The 2021 International Association for the Study of Pain (IASP) clinical criteria and grading system for nociplastic pain account for the need to identify and correctly classify patients according to the pain phenotype early in their treatment. These criteria are an important step towards precision pain medicine with great potential for the field of clinical oncology. Within this framework, the Cancer Pain Phenotyping (CANPPHE) Network, an international and interdisciplinary group of oncology clinicians and researchers from seven countries, applied the 2021 IASP clinical criteria for nociplastic pain to the growing population of those experiencing post-cancer pain. A manual is provided to allow clinicians to differentiate between predominant nociceptive, neuropathic, or nociplastic pain after cancer. A seven-step diagnostic approach is presented and illustrated using cases to enhance understanding and encourage effective implementation of this approach in clinical practice.

Changes in normalized mutual information in response to strength training: An ancillary analysis of a quasi-randomized controlled trial.

The aim of the present investigation was twofold. (1) to assess test-retest reliability of normalized mutual information (NMI) values extracted from the surface electromyography (sEMG) signal of muscles pairs of the upper body during dynamic bench press at a high load, and (2) to assess changes in NMI values from before to after a five-week quasi-randomized controlled bench press training intervention. For test-retest reliability, 20 strength trained males (age 25 ± 2 years, height 1.81 ± 0.07 m) performed two three-repetition maximum (3RM) tests in bench press, while sEMG was recorded from six upper body muscles. Tests were separated by 8.2 ± 2.9 days. For the training intervention, 17 male participants (age 26 ± 5 years, height 1.80 ± 0.07 m) trained bench press specific strength training for 5 weeks (TRA), while 13 male participants (age 23 ± 3 years, height 1.80 ± 0.08 m) constituted a control group (CON). 3RM bench press test and sEMG recordings were carried out before and after the intervention period. The NMI values ranged from poor to almost perfect reliability, with the majority displaying substantial reliability. TRA displayed a significant decrease in NMI values during the concentric phase for two agonist-agonist muscle pairs, while one agonist-agonist and two agonist-antagonist muscle pairs increased the NMI values during the eccentric phase. The observed changes did not exceed the minimal detectable threshold, and we therefore cannot surely ascertain that the changes observed in NMI values reflect genuine neural adaptations.

Fatigue-induced Alterations of the Patellar Tendon in Elite Sprint Track Cyclists.

This study aims to investigate morphological and mechanical properties and echogenicity of the patellar tendon (PT) after acute fatigue-induced alterations in sprint track cyclists. Fourteen elite track cyclists participated in this study. The exercise protocol consisted of three maximal start accelerations (over a distance of 62.5 m), one maximal start acceleration (at both 125 m and 250 m), and sprints from the standing start. Immediately after testing all measurements, PT stiffness and thickness were set at 5-10-15-20 mm distal from the apex of the patella and 5-10 mm proximal to the tibial tuberosity. CSA was set at proximal, middle, and distal, while echogenicity was at proximal and distal points. The results showed significant increases in PT stiffness at all reference points after start acceleration (p<0.001). PT thickness showed similar results for stiffness, except for location placed at TT-5 (p<0.001). CSA increased significantly in proximal, middle, and distal regions (p<0.001), while echogenicity of the tendon increased in proximal and distal regions (p<0.001) after start acceleration. Regional-dependent alterations of PT thickness and stiffness may be related to anatomical and physiological mechanisms due to acute isometric contraction in the initial phase of standing start. Tendon echogenicity might be also useful in monitoring tendon mechanical properties and defining acute fatigue-induced changes.

Effect of a home-based isometric handgrip training programme on systolic blood pressure in adults: A randomised assessor-blinded trial.

OBJECTIVES: To evaluate the effects of 20 weeks of home-based isometric handgrip training (IHT) compared with usual care on systolic blood pressure (SBP) in adults. DESIGN AND PARTICIPANTS: This was a randomised, controlled, assessor-blinded trial. Participants were randomised to either IHT (intervention group) or usual care (control group). INTERVENTIONS: Participants randomised to the intervention group performed a session of 16 min of effective workout home-based IHT three times per week for 20 weeks. Participants randomised to the control group were asked to continue their daily activities as usual. OUTCOMES: The primary outcome was the difference in SBP between groups over 20 weeks. Secondary outcomes were diastolic blood pressure, heart rate, handgrip strength, and self-administered home blood pressure measures. RESULTS: Forty-eight adults (mean [SD] age, 64 [8] years) were included in this trial. The adjusted between-group mean difference in SBP was 8.12 mmHg (95% CI 0.24 to 16.01, p = 0.04) - favouring the usual care group. No differences between groups were found in any of the home blood pressure measurements. CONCLUSIONS: This trial showed that 20 weeks of home-based isometric handgrip training was not superior compared to the usual care in lowering SBP.

Functional and morphological changes in shoulder girdle muscles after repeated climbing exercise.

This study aimed to investigate the acute effect of repeated climbing actions on functional and morphological measures of the shoulder girdle. Fifteen male indoor climbers participated in this study. All the climbers declared route level 6a+, as the best climbing grade (French climbing grade scale). Functional (range of motion - ROM and muscle strength), and morphological measurements (muscle/tendon stiffness and thickness) after a repeated climbing exercise protocol were analysed. The ROM and muscle strength showed significant decreases from baseline to Immediate-Post (IA) as well as significant increases from IA to 1 h-Post for all movements (p ≤ .001 for all). Muscle stiffness showed significant increases from baseline to IA after as well as significant decreases from IA to 1 h-Post for all muscles (p ≤ .001 for all). However, the thickness showed significant increases from baseline to IA for supraspinatus tendon and muscle thickness and occupation ratio (p ≤ .001 for all), while a significant decrease was observed in acromiohumeral distance (p ≤ .001). Significant decreases from IA to 1 h-Post were found for muscles/tendons and occupation ratio (p ≤ .001 for all), while a significant increase for AHD (p ≤ .001). Our data demonstrated acute alterations in tendon thickness due to acute signs of implement symptom in climbers.

Number of steps and systolic blood pressure: Do work and leisure matter?

The number of steps per day influences blood pressure and health. However, the association between steps at work and leisure and blood pressure is unknown. Thus, we aimed to investigate the association between the domain-specific number of steps and systolic blood pressure. A thigh-worn accelerometer was used to measure the steps of 694 workers over 1-5 consecutive days, separated into work and leisure domains using a self-reported diary. We linearly regressed steps at work, leisure and total day against systolic blood pressure, adjusting for age, sex, body mass index, smoking, and antihypertensive medication. Additionally, we stratified the analyses on job type (blue-collar or white-collar). The results of this cross-sectional analysis indicated a beneficial association between the number of steps (per 2000-step interval) and systolic blood pressure for the total day (-0.5 mmHg; -1.0 to -0.8, 95% CI, p < 0.05) and work (-0.9 mmHg; -1.5 to -0.4, 95% CI, p < 0.05), but not for leisure (+0.1 mmHg; -0.7 to 0.9, 95% CI, p = 0.75). Blue-collar workers took almost twice as many steps at work (9143 ± SD3837) as white-collar workers (5863 ± SD3565) and, after stratification on job type, we observed a beneficial association between the number of steps at work and systolic blood pressure among blue-collar workers (-1.1 mmHg; -1.7 to -0.4, 95% CI, p < 0.05), but not for white-collar workers (-0.3 mmHg; -1.7 to 1.1, 95% CI, p = 0.7). These findings indicate that the number of steps at work, particularly among blue-collar workers, is beneficially associated with systolic blood pressure. Such findings support the potential of work (re)design to promote walking to improve blood pressure.

Retirement status and frailty: a cross-sectional study of the phenotype of manual workers aged 50-70 years.

BACKGROUND: The frailty phenotype is predictive of mortality and has been identified in the working population. This cross-sectional study aimed to investigate the prevalence of frailty and individual frailty symptoms among active and retired Danish manual workers and to delineate the relationship between frailty and lifestyle factors. METHODS: Manual workers aged 50-70 years answered questions relating to the Fried criteria for frailty (weight loss, exhaustion, slowness, weakness and inactivity). Only men were included in the analyses and respondents were stratified according to work status: active workers (n = 1555), early retirees (n = 289) and workers retired at or after normal pension age (n = 291). Associations between pre-frailty/frailty, work status and various lifestyle factors were estimated using binomial logistic regression. RESULTS: Overall, the prevalence of pre-frailty (one or two symptoms) and frailty (three or more symptoms) was 33.3% and 1.5%, respectively. Those who had retired early were more likely to be pre-frail/frail compared with active workers (odds ratio 2.20, 95% CI 1.61-3.01). Exhaustion was the most prominent symptom reported by 22.2% of active workers, 34.6% of early retirees and 16.5% of workers retired at normal retirement age. Lifestyle factors including obesity, physical inactivity and smoking but not alcohol intake were associated with pre-frailty/frailty. CONCLUSION: Symptoms of frailty are identifiable and present among both active and retired manual workers. Data suggest discrepancies among Danish manual workers, with some having unhealthy lifestyles and being more prone to develop pre-frailty and frailty already in their sixth decade of life.

A field study investigating sensory manifestations in recreational female cyclists using a novel female-specific cycling pad.

This randomised controlled field study aimed to design a female-specific cycling pad with reduced padding in the crotch area (half-pad) and test its effects on self-reported sensory manifestations in comparison with full-padded cycling bib shorts. Recreational female road cyclists (n = 183) participated (divided into two groups). Self-reported sensory manifestations were collected six times over 12 weeks. Sitting discomfort, wetness perception, thermal, texture sensation, and wear discomfort decreased over time for the crotch and sitting-bones areas in both groups. Irritation and tenderness in the crotch area also decreased over time in both groups. Irritation and tenderness in the sitting-bones area were only higher at week two in the half-pad compared with the full-pad group. Cycling with the half-padded shorts compared with the full-padded ones had no negative effects on sensory manifestations beside the observed transient change at week two. This suggests that foam thickness in the crotch area can be reduced in female-specific cycling pads. Practitioner's Summary: Road cycling might result in discomfort and non-traumatic injuries in the female genital area. This field study compares two different cycling pads; a half-pad and a full-pad, over a 12-week period among female recreational road cyclists. Reducing the foam thickness in the crotch area of the pad does not change sensory manifestations, i.e. discomfort, wetness perception, texture-, and thermal-sensation as well as wear discomfort. Abbreviations: CS-Q: online Cycling bib Shorts Questionnaire; VADER: Valence Aware Dictionary and sEntiment Reasoner.

Eccentric Training Changes the Pressure Pain and Stiffness Maps of the Upper Trapezius in Females with Chronic Neck-Shoulder Pain: A Preliminary Study.

OBJECTIVE: Between 50% and 67% of adults suffer from neck-shoulder pain, which may be associated with increased stiffness of neck muscles. We assessed pressure pain sensitivity and muscle stiffness maps of the upper trapezius in female computer users with and without chronic neck-shoulder pain and investigated the effects of eccentric training on females with neck-shoulder pain. DESIGN: Cross-sectional (part 1) and open-label (part 2) study. SETTING: University. SUBJECTS: Twenty females with neck-shoulder pain were compared with 20 controls (part 1). In part 2, neck-shoulder pain participants followed a five-week unilateral upper trapezius eccentric training program. METHODS: Topographical maps of pressure pain thresholds (pressure algometer) and muscle stiffness (myotonometer), using a 15-point grid covering myotendinous and muscle belly sites, and shoulder elevation force and range of elevation (dynamometer) were assessed at baseline and after training. RESULTS: There were no differences in pressure pain thresholds between sites (P = 0.243) or groups (P = 0.068), and there were significant differences in stiffness between myotendinous and muscle belly sites (P < 0.001) but not groups (P = 0.273). After training, pressure pain thresholds increased, stiffness decreased (P < 0.005), and shoulder elevation force and range of elevation improved (P < 0.001). CONCLUSIONS: The lack of differences in upper trapezius pressure pain sensitivity and stiffness between females with or without neck-shoulder pain confirms no clear etiology among computer users reporting neck-shoulder pain. A five-week eccentric training protocol showed positive effects on pressure pain sensitivity, stiffness, shoulder force, and range of motion.

Physical exposure during patient transfer and risk of back injury & low-back pain: prospective cohort study.

BACKGROUND: Work-related musculoskeletal disorders (MSDs) are common among healthcare workers. Because frequent patient transfer has been associated with increased risk of MSDs, we aim to quantify the physical load associated with commonly-used assistive devices and to investigate associations between accumulated physical exposure and risk of MSDs. METHODS: By applying an exposure matrix based on objective measurements of electromyography and trunk flexion on a large (n = 1285) prospective cohort, intensity of low-back pain (LBP) and odds of back injury at 1-year follow-up were modelled using linear models and logistic regressions, respectively. The cohort was divided into groups according to physical exposure; i.e. low (1st quartile), moderate (2nd and 3rd quartiles) and high (4th quartile) exposure. RESULTS: Exposure profiles are provided for 9 groups of assistive devices, with ceiling lifts and intelligent beds eliciting the lowest physical exposure. In the fully-adjusted model, we report differences in LBP intensity at follow-up between the low and moderate exposure groups (p = 0.0085). No difference was found between the moderate and high exposure groups (p = 0.2967). Likewise, we find no associations between physical exposure and odds of back injury at 1-year follow-up, with a prevalence of 11, 13 and 11% for the three groups, respectively. CONCLUSIONS: Low physical exposure during patient transfer was prospectively associated with lower intensity of LBP. Consistent use of assistive devices associated with low physical exposure, namely ceiling-lifts and intelligent beds, may play a role in reducing the incidence of MSDs among healthcare workers.

Biomechanical load during patient transfer with assistive devices: Cross-sectional study.

This study utilised a cross-sectional design to perform measurements of muscle activity as well as forward - and lateral trunk inclination angle during a full workday among 52 female healthcare workers from 16 different departments at five Danish hospitals. Using linear mixed models, the 95th percentile ranks of the normalised root mean square (nRMS) values were analysed for the different types of assistive devices. Compared to no assistive device (mean nRMS 27.9%, 95% CI 24.8%-31.0%), the use of intelligent beds (23.9%, CI 20.2%-27.6%) and ceiling-lifts (24.0%, CI 20.3%-27.7%) led to lower erector spinae nRMS values across all types of patient transfers. Conversely, the use of bedsheets (30.6%, CI 27.1%-34.2%), sliding-sheets (30.3%, CI 26.8%-33.9%) and sliding-boards (33.5%, CI 29.5%-37.6%) were associated with higher levels of erector spinae muscle activity.Consistent use of ceiling-lifts and intelligent beds reduces the physical workload and may thereby decrease the risk of musculoskeletal disorders among healthcare workers. Practioner Summary: Frequent patient transfer is associated with an increased risk of back pain and injury among healthcare workers. This analysis compares the level of physical load during patient transfer with commonly used assistive devices. The results show that use of the ceiling-lift and intelligent bed is associated with relatively low physical load during patient transfer. Abbreviations: RMS: root mean square; nRMS: normalized root mean square; EMG: electromyography; MSD: musculoskeletal disorder; LBP: low-back pain; VAS: visual analogue scale; MVC: maximal voluntary contraction.

Physical-work ability and chronic musculoskeletal complaints are related to leisure-time physical activity: Cross-sectional study among manual workers aged 50-70 years.

AIMS: To investigate the associations between both high- and low-intensity leisure-time physical activity on physical-work ability and chronic musculoskeletal complaints among manual workers aged 50-70 years. METHODS: In this cross-sectional study, 1763 manual workers (mean age 57.1, SD ± 4.7 years) replied to questions about leisure-time physical activity, physical-work ability, chronic musculoskeletal complaints as well as health and lifestyle factors. Ordinal and binomial logistic regression models were constructed to assess the influence of the duration of both low- and high-intensity physical activity on physical-work ability and chronic musculoskeletal complaints, respectively. Models were adjusted for gender, age, smoking, alcohol intake, body mass index, physical-work demand, work experience, chronic disease and, regarding physical-work ability, also for chronic musculoskeletal complaints. RESULTS: A statistically significant association between greater physical-work ability and high-intensity physical activity was found for workers engaged in 3-4 h/wk and ⩾ 5 h/wk (OR 1.59, 95% CI 1.15-2.19 and OR 1.56, 95% CI 1.10-2.22, respectively). For both high- and low-intensity physical activity, a duration of 3-4 h/wk was associated with lower odds of reporting chronic musculoskeletal complaints in the knees (OR 0.65, 95% CI 0.42-1.00 and OR 0.61, 95% CI 0.38-0.99, respectively). CONCLUSIONS: Engaging in ⩾ 3 h/wk of high-intensity leisure-time physical activity was associated with greater physical-work ability among manual workers aged 50-70 years. Both high- and low-intensity physical activity related to lower odds of having chronic musculoskeletal complaints in the knees.

Later stages of diabetic neuropathy affect the complexity of the neuromuscular system at the knee during low-level isometric contractions.

INTRODUCTION: This study evaluates the complexity of force and surface electromyography (sEMG) during knee extension and flexion at low-level isometric contractions in individuals with different degrees of diabetic peripheral neuropathy (DPN). METHODS: Ten control and 38 diabetic participants performed isometric contractions at 10%, 20%, and 30% of maximal voluntary contraction. Knee force and multichannel sEMG from vastus lateralis (VL) and biceps femoris were acquired. The SD of force and sample entropy (SaEn) of both force and sEMG were computed. RESULTS: Participants with moderate DPN demonstrated high force-SD and low force-SaEn. Severely affected participants showed low SaEn in VL at all force levels. DISCUSSION: DPN affects the complexity of the neuromuscular system at the knee for the extension task during low-level isometric contractions, with participants in the later stages of the disease (moderate and severe) demonstrating most of the changes. Muscle Nerve 57: 112-121, 2018.

Effects of a Participatory Ergonomics Intervention With Wearable Technical Measurements of Physical Workload in the Construction Industry: Cluster Randomized Controlled Trial.

BACKGROUND: Construction work frequently involves heavy physical work, and a reduction of the physical workload should have high priority. Technological development has made it possible to obtain field measurements with surface electromyography (sEMG), kinematics measured with inertial measurement units (IMUs), and video recordings. However, no studies have used these methods simultaneously to detect situations with excessive physical workload (events) during a working day. Thus, knowledge about these specific events may combat work-related risk factors. Participatory ergonomics (PE) has shown promising results, but whether it can be used as a tool to reduce the physical workload during construction work remains unknown. OBJECTIVE: This cluster randomized controlled trial investigated whether a PE intervention with technical measurements consisting of IMUs, sEMG, heart rate monitoring, and video recordings of physical workload could reduce the number of events with excessive physical workload during a working day. Furthermore, other outcomes were obtained from questionnaires. METHODS: A total of 80 male full-time construction workers (aged 19 to 67 years) were randomized at the cluster level (gang) to a PE intervention consisting of 3 workshops (7 gangs and 32 workers) or to a control group (8 gangs and 48 workers). The physical workload was recorded by technical measurements, that is, IMUs, sEMG, heart rate monitoring, and video recordings during a full working day at baseline and 3 and 6 months' follow-up. On the basis of the technical measurements, a custom-made computer program detected the situations (events) where the construction workers were exposed to excessive physical workload and used in the intervention. Differences in the number of events from baseline to follow-up between intervention and control were evaluated using linear mixed models (intention-to-treat), with individual nested in cluster as a random factor. Furthermore, questionnaires were filled out on test days. RESULTS: The results of the primary outcome showed no change in the number of events with excessive physical workload. However, compared with the control group, the other outcomes showed decreased general fatigue after a typical working day (P=.001) and increased influence on own work (P=.04). CONCLUSIONS: This PE intervention with technical measurements did not reduce the number of events with excessive physical workload during construction work. However, the intervention led to decreased general fatigue and increased influence on own work. TRIAL REGISTRATION: ClinicalTrials.gov NCT02498197; https://clinicaltrials.gov/ct2/show/NCT02498197 (Archived by WebCite at http://www.webcitation.org/74SZ3DIWS).

External and Internal Focus of Attention Increases Muscular Activation During Bench Press in Resistance-Trained Participants.

Kristiansen, M, Samani, A, Vuillerme, N, Madeleine, P, and Hansen, EA. External and internal focus of attention increases muscular activation during bench press in resistance-trained participants. J Strength Cond Res 32(9): 2442-2451, 2018-Research on the effects of instructed attentional focus during execution of strength training exercises is limited and has thus far only been performed on single-joint exercises. The aim of this study was to compare the effects of instructed internal (INT) and external (EXT) focus of attention with a baseline measurement of no instructed focus of attention (BASE) on the surface electromyographic (EMG) amplitude during a free-weight bench press exercise in resistance-trained participants. Twenty-one resistance-trained male participants performed bench press at 60% of their 3-repetition maximum, with BASE, EXT, and INT. The order of EXT and INT was randomized and counterbalanced. Electromyographic data were recorded from 13 muscles of the upper and lower body. Subsequently, mean and peak EMG amplitudes were computed. EXT and INT resulted in significantly increased mean EMG amplitude of 6 upper-body muscles as compared with BASE (p ≤ 0.05). In addition, EXT and INT also resulted in increased peak EMG amplitude of 3 upper-body muscles as compared with BASE (p ≤ 0.05). These results show that muscular activation is increased during bench press, when applying an instructed focus of attention compared with a baseline measurement with no focus instructions (BASE).

Accuracy of identification of low or high risk lifting during standardised lifting situations.

The aim was to classify lifting activities into low and high risk categories (according to The Danish Working Environment Authority guidelines) based on surface electromyography (sEMG) and trunk inclination (tri-axial accelerometer) measurements. Lifting tasks with different weights, horizontal distance and technique were performed. The lifting tasks were characterised by a feature vector composed of either the 90th, 95th or 99th percentile of sEMG activity level and trunk inclinations during the task. Linear Discriminant Analysis and a subject-specific threshold scheme were applied and lifting tasks were classified with an accuracy of 65.1-65.5%. When lifts were classified based on the subject-specific threshold scheme from low and upper back accelerometers, the accuracy reached 52.1-58.1% and 72.7-78.1%, respectively. In conclusion, the use of subject-specific thresholds from sEMG from upper trapezius and erector spinae as well as inclination of the upper trunk enabled us to identify low and high risk lifts with an acceptable accuracy. Practitioner Summary: This study contributes to the development of a method enabling the automatic detection of high risk lifting tasks, i.e. exposure to high biomechanical loads, based on individual sEMG and kinematics from an entire working day. These methods may be more cost-effective and may complement observations commonly used by practitioners.

Variability in spatio-temporal pattern of trapezius activity and coordination of hand-arm muscles during a sustained repetitive dynamic task.

The spatio-temporal distribution of muscle activity has been suggested to be a determinant of fatigue development. Pursuing this hypothesis, we investigated the pattern of muscular activity in the shoulder and arm during a repetitive dynamic task performed until participants' rating of perceived exertion reached 8 on Borg's CR-10 scale. We collected high-density surface electromyogram (HD-EMG) over the upper trapezius, as well as bipolar EMG from biceps brachii, triceps brachii, deltoideus anterior, serratus anterior, upper and lower trapezius from 21 healthy women. Root-mean-square (RMS) and mean power frequency (MNF) were calculated for all EMG signals. The barycenter of RMS values over the HD-EMG grid was also determined, as well as normalized mutual information (NMI) for each pair of muscles. Cycle-to-cycle variability of these metrics was also assessed. With time, EMG RMS increased for most of the muscles, and MNF decreased. Trapezius activity became higher on the lateral side than on the medial side of the HD-EMG grid and the barycenter moved in a lateral direction. NMI between muscle pairs increased with time while its variability decreased. The variability of the metrics during the initial 10 % of task performance was not associated with the time to task termination. Our results suggest that the considerable variability in force and posture contained in the dynamic task per se masks any possible effects of differences between subjects in initial motor variability on the rate of fatigue development.

Differences in Topographical Pressure Pain Sensitivity Maps of the Scalp Between Patients With Migraine and Healthy Controls.

OBJECTIVE: To investigate differences in topographical pressure pain sensitivity maps of the scalp between patients with migraine and healthy controls considering the chronicity (episodic/chronic) and side (strictly unilateral/bilateral) of the symptoms. BACKGROUND: It seems that the trigeminal area is sensitized in migraine. No study has investigated topographical pressure sensitivity maps of the scalp in patients with migraine. METHODS: Pressure pain thresholds (PPTs) were assessed from 21 points distributed over the scalp in 86 patients with episodic migraine, 76 with chronic migraine, and 42 healthy age and matched healthy controls in a blinded design. Topographical pressure pain sensitivity maps based on interpolation of the PPTs were constructed. Clinical features of migraine, anxiety, and depression (Hospital Anxiety and Depression Scale, HADS) were collected. RESULTS: The multivariate ANCOVA revealed significant differences in PPT between points (F = 55.674; P < .001) and groups (F = 5.316; P = .006), but not sides (F = 0.880; P = .417). No significant effect of gender (F = 0.897; P = .656), depression (F = 1.109; P = .220), or anxiety (F = 0.981; F = 0.569) was found. Post hoc comparisons revealed: (1) lower PPTs in both migraine groups than in healthy controls in all points (P < .001); (2) no significant differences between chronic or episodic migraine (P > .335) except for Fp1 (P = .045) and Fp2 (P = .017) points where subjects with chronic migraine had lower PPTs than those with episodic migraine; (3) no differences between bilateral/unilateral migraine (P > .417). An anterior to posterior gradient was found, with the lowest PPTs located in frontal regions and the highest PPTs in occipital areas (all groups, P < .001). CONCLUSIONS: We found that patients with migraine exhibited generalized pressure pain hypersensitivity in the head as compared to healthy controls and that hypersensitivity was similar between episodic/chronic and unilateral/bilateral migraine. Topographical pressure pain sensitivity maps revealed an anterior to posterior gradient of pressure pain sensitivity in both migraine and control groups.

Inter-day reliability of surface electromyography recordings of the lumbar part of erector spinae longissimus and trapezius descendens during box lifting.

BACKGROUND: Low back pain and neck-shoulder pain are the most reported types of work-related musculoskeletal disorders, and performing heavy lifting at work and working with trunk rotation increase the risk of developing work-related musculoskeletal disorders. Surface electromyography (sEMG) provides information about the electrical activity of muscles. Thus it has the potential to retrieve indirect information about the physical exposure of specific muscles of workers during their actual work. This study aimed to investigate the inter-day reliability of absolute and normalized amplitude of sEMG measurements obtained during repeated standardized reference lifts. METHODS: The inter-day reliability of sEMG of the erector spinae longissimus and trapezius descendens muscles was tested during standardized box lifts. The lifts were performed with loads of 3, 15 and 30 kg from floor to table and from table to table in three conditions, i.e., forearm length (short reaching distance), ¾ arm length (long reaching distance) and forearm length with trunk rotation. Absolute and normalized root mean square (absRMS and normRMS) values were extracted. In line with the guidelines for reporting reliability and agreement studies, we reported relative and absolute reliability estimated by intra class correlation (ICC3,K), standard error of measurement (SEM) and minimal detectable change in percent (MDC). RESULTS: The ICC3,K was higher for absRMS compared with normRMS while SEM and maximal voluntary contraction (MVC) were similar. A total of 50 out of 56, i.e., 89%, and 41 out of 56, i.e., 73%, of the lifting situations were in the range from moderate to almost perfect for absRMS and normRMS, respectively. The SEM and MDC shoved more variation in the lifting situations performed from floor to table and in the trapezius descendens muscle than in the erector spinae longissimus muscle. CONCLUSION: This reliability study showed that maximum absRMS and normRMS were found to have a fair to substantial relative inter-day reliability for most lifts but were more reliable when lifting from table to table than from floor to table for both trapezius descendens and erector spinae muscles. The relative inter-day reliability was higher for absolute compared with normalized sEMG amplitudes while the absolute reliability was similar.