Effects of upper-limb exoskeleton on muscle activity in tasks requiring arm elevation: Part II - In-field experiments in construction industry settings.

Background: The body of literature regarding the use of an upper limb exoskeleton during authentic working conditions is sparse. Objective: The aim of this study was to evaluate the effectiveness of an upper limb exoskeleton in reducing muscle strain during authentic industrial construction work. Methods: Fifteen male participants, comprising of roofers, scaffolders, builders, bricklayers, and graders performing overhead work participated in the study. During work without (REF) and with exoskeleton (EXO), muscle activity from 8 muscles, heart rate (HR), metabolic equivalent (MET), and upper arm elevation angles were recorded. Results: When using the exoskeleton, a significant reduction of 20.2% in average muscle activity of 8 muscles was found. The largest effect focused on m. deltoideus, where 46.2 and 32.2% reduction occurred in medial and anterior parts of the muscle, respectively. HR and MET were unaffected. Upper arm elevation angles were similar between REF and EXO, indicating equal biomechanical loading. Conclusions: This study indicates that exoskeletons show great promise in reducing the potential for musculoskeletal strain during authentic overhead construction work.

Effects of an exoskeleton on muscle activity in tasks requiring arm elevation: Part I - Experiments in a controlled laboratory setting.

BACKGROUND: Long-term work with elevated arms, or overhead work, is a risk factor for musculoskeletal complaints and disorders. Upper-limb exoskeletons are a promising tool for reducing occupational workload when working with hands above shoulder level. OBJECTIVE: The purpose of this study was to assess the effects of upper-limb exoskeleton on muscular and physical strain and perceived exertion during dynamic work at four different shoulder joint angles. Further, we evaluated if there are any negative effects associated with the use of exoskeleton. METHODS: A total of 15 student participants performed dynamic work in laboratory setting with and without an exoskeleton at four different shoulder angles: 60, 90, 120 and 150 degrees. Muscle electrical activity from 8 muscles of the upper body, perceived exertion, and heart rate were measured during the work task, and grip strength, muscle stiffness, tone, and elasticity from six muscles, m. deltoideus physiological cross-sectional area and muscle fiber pennation angle, and nerve conduction velocity were measured before and after the work task. RESULTS: Based on the results, the use of exoskeleton significantly reduced the muscle activity of the upper limb, shoulder, and back muscles. The reduction was most significant when the arm elevation was 120°, and in m. deltoideus muscle activity. RPE was also positively affected indicating reduction in workload when using exoskeleton. CONCLUSION: The results suggest that the use of upper limb exoskeleton has potential to reduce physical workload during overhead work and, consequently, reduce the risk for work-related musculoskeletal disorders.

Relationship between occupational and leisure-time physical activity and the need for recovery after work.

BACKGROUND: Health benefits of physical activity are very well acknowledged but the role of both occupational physical activity (OPA) and leisure time physical activity (LTPA) in recovery after work is not thoroughly understood. The purpose of this study was to investigate the association between accelerometer-measured OPA and LTPA and the need for recovery after work (NFR) in early childhood education and care (ECEC) professionals. METHODS: The study participants were 217 female ECEC professionals aged 17-64. Physical activity was recorded with a three-axis accelerometer (ActiGraph GT9X Link, ActiGraph, USA) for seven consecutive days. Separate analyses were conducted for both OPA and LTPA and reported as hours/day based on different intensity levels (light, moderate, vigorous, very vigorous). The NFR was measured with the Need For Recovery (NFR) scale (0%-100%). RESULTS: Participants' average physical activity for both OPA and LTPA was about 4 h/day, and the mean NFR score was 38.4%. OPA was significantly associated with the NFR but not with LTPA. The relationship remained significant after adjustments for age, body mass index, work ability, mental health status, and sleep difficulties (p < 0.024). CONCLUSION: According to this study, the OPA level is related to the level of the NFR in female ECEC professionals. Based on the results, it seems that LTPA has no relevance to the NFR. Results suggest that long-lasting OPA, even without strenuous physical activity at work, may predispose individuals to a high NFR.

Association between lowered endothelial function measured by peripheral arterial tonometry and cardio-metabolic risk factors - a cross-sectional study of Finnish municipal workers at risk of diabetes and cardiovascular disease.

BACKGROUND: The aim of this cross-sectional study was to determine the association between lowered endothelial function measured by peripheral arterial tonometry (PAT) and cardio-metabolic risk factors. The study population consisted of Finnish municipal workers who were at risk of diabetes or cardiovascular disease and who had expressed a need to change their health behaviour. METHODS: A total of 312 middle-aged municipal workers underwent a physical medical examination and anthropometry measurements. Levels of total cholesterol, HDL cholesterol, triglycerides, fasting glucose, glycated haemoglobin, and high sensitivity C-reactive protein were taken from the blood samples. PAT measured the increase in digital pulse volume amplitude during reactive hyperemia, and the index of endothelial function, F-RHI, was defined as the ratio of post-deflation amplitude to baseline amplitude. RESULTS: In the linear regression model, male sex was associated with lower F-RHI. In sex-adjusted linear regression models, each of the variables; waist circumference, fasting glucose, glycated hemoglobin, triglycerides, body fat percentage, body mass index, current smoking, and impaired fasting glucose or diabetes were separately associated with lower F-RHI, and HDL cholesterol and resting heart rate were associated with higher F-RHI.HDL cholesterol, sex, body mass index, and current smoking entered a stepwise multivariable regression model, in which HDL cholesterol was associated with higher F-RHI, and smoking, male sex and body mass index were associated with lower F-RHI. This model explains 28.3% of the variability in F-RHI. CONCLUSIONS: F-RHI is associated with several cardio-metabolic risk factors; low level of HDL cholesterol, male sex, overweight and smoking being the most important predictors of a lowered endothelial function. A large part of variation in F-RHI remains accounted for by unknown factors.

The effects of plant stanol ester consumption on arterial stiffness and endothelial function in adults: a randomised controlled clinical trial.

BACKGROUND: The hypocholesterolemic effect of plant stanol ester consumption has been studied extensively, but its effect on cardiovascular health has been less frequently investigated. We studied the effects of plant stanol esters (staest) on arterial stiffness and endothelial function in adults without lipid medication. METHODS: Ninety-two asymptomatic subjects, 35 men and 57 women, mean age of 50.8±1.0 years (SEM) were recruited from different commercial companies. It was randomized, controlled, double-blind, parallel trial and lasted 6 months. The staest group (n=46) consumed rapeseed oil-based spread enriched with staest (3.0 g of plant stanols/d), and controls (n=46) the same spread without staest. Arterial stiffness was assessed via the cardio-ankle vascular index (CAVI) in large and as an augmentation index (AI) in peripheral arteries, and endothelial function as reactive hyperemia index (RHI). Lipids and vascular endpoints were tested using analysis of variance for repeated measurements. RESULTS: At baseline, 28% of subjects had a normal LDL cholesterol level (≤3.0 mmol/l) and normal arterial stiffness (<8). After the intervention, in the staest group, serum total, LDL, and non-HDL cholesterol concentrations declined by 6.6, 10.2, and 10.6% compared with controls (p<0.001 for all). CAVI was unchanged in the whole study group, but in control men, CAVI tended to increase by 3.1% (p=0.06) but was unchanged in the staest men, thus the difference in the changes between groups was statistically significant (p=0.023). AI was unchanged in staest (1.96±2.47, NS) but increased by 3.30±1.83 in controls (p=0.034) i.e. the groups differed from each other (p=0.046). The reduction in LDL and non-HDL cholesterol levels achieved by staest was related to the improvement in RHI (r=-0.452, p=0.006 and -0.436, p=0.008). CONCLUSIONS: Lowering LDL and non-HDL cholesterol by 10% with staest for 6 months reduced arterial stiffness in small arteries. In subgroup analyses, staest also had a beneficial effect on arterial stiffness in large arteries in men and on endothelial function. Further research will be needed to confirm these results in different populations. TRIAL REGISTRATION: Clinical Trials Register # NCT01315964.

Diet and cardiovascular health in asymptomatic normo- and mildly-to-moderately hypercholesterolemic participants - baseline data from the BLOOD FLOW intervention study.

BACKGROUND: For decades in Finland, intensive population strategies and preventive activities have been used to lower the risk of atherosclerotic coronary heart disease (CHD). Lifestyle changes, with the emphasis on diet, play an important role in preventive strategies. The aim of this study was to evaluate arterial stiffness and endothelial function in asymptomatic free-living adults and to relate the results to CHD risk factors and lifestyle habits with the emphasis on diet. METHODS: Ninety-four asymptomatic participants were recruited by advertisements in four large companies and two research institutes employing mainly office workers. Arterial stiffness was assessed as the cardio-ankle vascular index in large arteries, and endothelial function as the reactive hyperemia index with peripheral arterial tonometry. The systematic Cardiovascular Risk Estimation (SCORE) was calculated. RESULTS: The data was collected in the spring of 2011. Anthropometric, dietary, and lipid data was available from 92 participants, blood pressure from 85 and vascular measurements from 86-88 subjects (38% males; 62% females; mean age of all 51). The majority (72%) had an elevated low density lipoprotein (LDL) cholesterol concentration and over half were overweight or obese. SCORE stated that 49% of the participants had a moderate risk of cardiovascular disease. When compared to general recommendations, half of the participants had too high intake of total fat and in 66% the consumption of saturated fat was too high. In contrast, the intake of carbohydrates was too low in 90% of the participants and for fiber 73% were below recommendations. There was evidence of borderline or increased arterial stiffness in 72% of the participants and endothelial function was impaired in 8%. Arterial stiffness was associated with LDL cholesterol concentration (p = 0.024), dietary cholesterol intake (p = 0.029), and SCORE (p < 0.001). CONCLUSIONS: In a cross-sectional study of asymptomatic middle-aged participants, the half had a moderate risk for cardiovascular diseases manifested as increased arterial stiffness, elevated LDL cholesterol concentration, and poor dietary habits. The new observation that arterial stiffness was associated with dietary cholesterol intake and SCORE emphasizes the urgency of adequate lifestyle and dietary interventions to prevent future coronary events even in asymptomatic participants. TRIAL REGISTRATION: Clinical Trials Register # NCT01315964.

Thermal effects of mobile phone RF fields on children: a provocation study.

The aim of this study was to examine thermal and local blood flow responses in the head area of the preadolescent boys during exposure to radiofrequency (RF) electromagnetic fields produced by a GSM mobile phone. The design was a double-blinded sham-controlled study of 26 boys, aged 14-15 years. The SAR distribution was calculated and modelled in detail. The duration of the sham periods and exposures with GSM 900 phone was 15 min each, and the tests were carried out in a climatic chamber in controlled thermoneutral conditions. The ear canal temperatures were registered from both ear canals, and the skin temperatures at several sites of the head, trunk and extremities. The local cerebral blood flow was monitored by a near-infrared spectroscopy (NIRS), and the autonomic nervous system function by recordings of ECG and continuous blood pressure. During the short-term RF exposure, local cerebral blood flow did not change, the ear canal temperature did not increase significantly and autonomic nervous system was not interfered. The strengths of this study were the age of the population, multifactorial physiological monitoring and strictly controlled thermal environment. The limitations of the study were large inter-individual variation in the physiological responses, and short duration of the exposure. Longer provocation protocols, however, might cause in children distress related confounding physiological responses.