Search results for " environmental and occupational health"
showing 10 items of 3874 documents
Human isometric force production and electromyogram activity of knee extensor muscles in water and on dry land.
1999
This study was designed to determine trial-to-trial and day-to-day reproducibility of isometric force and electromyogram activity (EMG) of the knee extensor muscles in water and on dry land as well as to make comparisons between the two training conditions in muscle activity and force production. A group of 20 healthy subjects (12 women and 8 men) were tested three times over 2 weeks. A measurement session consisted of recordings of maximal and submaximal isometric knee extension force with simultaneous recording of surface EMG from the vastus medialis, vastus lateralis and biceps femoris muscles. To ensure identical measurement conditions the same patient elevator chair was used in both th…
Electromechanical behaviour of human muscles in vertical jumps
1982
The relationships of muscle structure to the potentiation of myoelectrical activity and to the use of prestretching in five lower limb muscles were studied in different vertical jumping conditions. The subjects for the study were six male students, divided according to the muscle fiber distribution in m. vastus lateralis into “fast” and “slow” groups. The subjects performed vertical jumps (1) from a static squatting position (SJ), (2) with a preliminary counter movement (CMJ) and (3) after dropping (DJ) from five different heights. Myoelectrical (EMG) activity was recorded from mm. gluteus maximus, vastus lateralis, vastus medialis, rectus femoris and gastrocnemius in each jumping condition…
Mechanical characteristics and fiber composition of human leg extensor muscles.
1979
To investigate the influence of skeletal muscle fiber composition on the mechanical performance of human skeletal muscle under dynamic conditions, 34 physical education students with differing muscle fiber composition (M. vastus lateralis) were used as subjects to perform maximal vertical jumps on the force-platform. Two kinds of jumps were performed: one from a static starting position (SJ), the other with a preliminary counter-movement (CMJ). The calculated mechanical parameters included height of rise of center of gravity (h), average force (F), net impulse (NI) and average mechanical power (W). It was observed that the percentage of fast twitch fibers was significantly related (p less t…
Predictors of weight loss after an intensive lifestyle intervention program in obese patients: a 1-year prospective cohort study.
2013
Published Version of an article in the journal: Health and Quality of Life Outcomes. Also available from the publisher at: http://dx.doi.org/10.1186/1477-7525-11-165 Open access Background Studies of lifestyle intervention programs in morbid obesity report large variations in weight loss outcomes. This is reported not only between but also within standardized programs. Such reports point to participants’ characteristics as possible predictors of this outcome. The aim of this prospective cohort study was to identify predictors of weight loss after a 1-year partly residential intensive lifestyle intervention program (ILI). Methods Morbidly obese patients (n=199), all Caucasian, 71% women, mea…
Electromechanical delay in human skeletal muscle under concentric and eccentric contractions.
1979
In contraction of skeletal muscle a delay exists between the onset of electrical activity and measurable tension. This delay in electromechanical coupling has been stated to be between 30 and 100 ms. Thus, in rapid movements it may be possible for electromyographic (EMG) activity to have terminated before force can be detected. This study was designed to determine the dependence of the EMG-tension delay upon selected initial conditions at the time of muscle activation. The right forearms of 14 subjects were passively oscillated by a motor-driven dynamometer through flexion-extension cycles of 135 deg at an angular velocity of approximately equal to 0.5 rad/s. Upon presentation of a visual s…
Age groups changes in self-rated health: A prospective longitudinal study over a 20-year period using Health Survey of North Trøndelag data.
2020
Background: The aim of the study was to investigate changes in self-rated health (SRH) between different age groups and sexes over a 20-year period. Methods: Data were retrieved from the large longitudinal Health Survey of North Trøndelag, Norway, which includes data collected from more than 190,000 participants aged 20–70+ years between the years 1984 and 2008. Data were analysed using logistic regression and adjusted for sex. Results: From 1984 to 2008, the odds of scoring higher on SRH decreased by 46% in the youngest age group (20–29 years) and increased by approximately 35% in the middle-aged and older age groups (40–70+ years). When considering sex differences, women in most age grou…
Has life satisfaction in Norway increased over a 20-year period? Exploring age and gender differences in a prospective longitudinal study, HUNT.
2017
Aim: The aim of the present study was to investigate the change in overall life satisfaction for different age groups and between genders over a 20-year period. Methods: Data from 1984 to 2008 were extracted from a large prospective longitudinal health study of Nord-Trøndelag (HUNT), Norway. The study included more than 176,000 participants ranging from 20 to 70+ years of age. Data were analysed using logistic regression and adjusted for gender. Results: The analyses revealed an increase in life satisfaction for all age groups from 1984–1986 (HUNT 1) to 1995–1997 (HUNT 2), with the highest levels being reached at 2006–2008 (HUNT 3). For all age groups, the data showed an increase of about …
Overcommitment as a predictor of effort-reward imbalance: evidence from an 8-year follow-up study.
2016
Objective The effort–reward imbalance (ERI) model includes the personal characteristic of overcommitment (OC) and the job-related characteristics of effort, reward, and ERI, all of which are assumed to play a role in an employee’s health and well-being at work. The aim of the present longitudinal study was to shed more light on the dynamics of the ERI model by investigating the basic hypotheses related to the role of OC in the model, ie, to establish whether an employee’s OC could be a risk factor for an increased experience of high effort, low reward, and high ERI at work. Methods The study was based on 5-wave, 8-year follow-up data collected among Finnish professionals in 2006 (T1, N=747)…
Alterations of mechanical characteristics of human skeletal muscle during strength training
1983
To investigate the influence of strength training on the mechanical characteristics of human skeletal muscle, 14 male subjects went through training of combined heavy concentric and eccentric contractions three times a week for 16 weeks. The strength training program consisted mainly of dynamic exercises for leg extensors with loads of 80 to 120% of one maximum repetition. The force-time curves produced during various vertical jumps were the basis for calculation of various mechanical parameters. In addition to a great increase (p less than 0.001) in maximal isometric force, heavy resistance strength training also caused significant (p less than 0.05-0.01) increases in heights and in variou…
From Office Environmental Stressors to Work Performance: The Role of Work Patterns
2018
Background: Different studies have shown a relationship between office environmental stressors and performance. However, studying environmental stress in the workplace requires analyzing more specific patterns to generate knowledge about the type of employees who are more or less vulnerable to environmental stressors. The present study analyzes the mediating role of health symptoms and negative emotions in the relationship between stressors and performance in different work patterns (task complexity and interactivity). Methods: There were 83 office workers (n = 603 time points) that took part in a diary study with multilevel design. Results: The appraisal of the environmental stressors is p…