An interventional study of interruptions of work tasks in Muscle Fatigue and Trapezius Muscle Strain, sponsored by Swiss Federal Institute of Technology. Completed. Open to participants aged 18 Years to 40 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2019-03-05.
Sponsored by Swiss Federal Institute of Technology · Not applicable, Interventional, and Prevention
This study is expected to demonstrate that during experimental days of seated computer work sustained and focalized low-level muscle activity contributes to the development of long-lasting fatigue effects (and thus possible disorder). On days with and without frequent interruptions, signs of fatigue and the activity pattern of the trapeze muscle are registered and compared using electromyographic registrations of the trapezius muscle.
30 healthy adults without chronic neck pain participated in a laboratory study designed to simulate two full workdays of computer work. Within each session, participants performed five 50-min working activities separated by 10-min breaks: i) Use a computer keyboard to type a text presented on the left side of the screen; ii) do the typing task with the desk height set10 cm above elbow height; iii) play the computer game Spider Solitaire implemented in Windows 10; iv) Stroop test (This test consists of reading the name of a color whose text is in a color different from the name. The color name was then selected from a multiple-choice panel displaying color names; v) the same online puzzle game was presented to all participants. Assembling the puzzle was performed by drag and drop actions. The work periods were not disrupted (on the "control day") whereas two short interruptions of 5-min were introduced at 1/3 and 2/3 of each working period on the "intervention day". During these interruptions, participants were asked to perform "muscle disrupting/relaxing" activities. For each experimental session a 30-min lunch break took place between the third and the fourth work periods. The specific sequence of work activity type and disrupting/relaxing activities was randomized across participants; however, for each participant the order of work activities remained the same for the two experimental sessions (control and intervention days). The order of control and intervention days was also randomized between participants.
A set of six measures were performed at specific time intervals during each experiment: before the first work activity, before and after lunch, immediately and 1 hour after the fifth (last) work activity: i) upper trapezius activation, assessed through the temporal EMG profile recorded by a single bipolar signal; and ii) through the spatio-temporal distribution of EMG activity detected by a 2D array of electrodes (64 channels); iii) muscle fatigue, quantified by changes in electrically induced muscle twitch force signals, iv) isometric performance, v) dynamic performance; iii) cognitive and physical load and stress level. In addition, personality traits (anxiety level), perceived workload and musculoskeletal symptoms were evaluated as covariates.
1,863 studies on the registry are indexed under Fatigue; 377 are open to participants now.
This study's enrollment of 30 is below the median of 54 across 1,443 interventional studies indexed under Fatigue.
Browse Fatigue studies →Swiss Federal Institute of Technology is the lead sponsor of 152 studies on the registry; 10 are open to participants now.
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Exclusion Criteria:
randomly start with or without short interruptions on the first experimental day and without or with them on the second experimental day
Behavioral: interruptions of work tasks
During each activity two interruptions/breaks were selected randomly from a set of ten predetermined actions: Active break types: * Move shoulder and upper back * Swing arms near the body * Three slow but forceful elevations of the shoulders, a relaxation exercise based on the principles developed by Jacobson * Stand up and stretch * Slowly turn head in all possible directions. Passive break types: * Tell a couple of jokes * Stand up and have a drink * Relaxing the trapezius * Questions on actual posture and feelings of comfort / discomfort. * A short rest on the couch
EMG profile recorded by a single bipolar electrode: Rest-time
Rest-time (percentage of time below 5% of the standard activity level). The percentage of registration time without any rest time is called sustained low level muscle activity.
Time frame: Continuously from the beginning to 370 min (end) of the simulated working activity of both the control and intervention day
Spatio-temporal distribution of EMG activity: Area of muscle activity
The spatio-temporal distribution of EMG activity is detected by a 2D array of electrodes (64 channels) and the following outcomes are determined: Area of muscle active region (n. of channels)
Time frame: Continuously from the beginning to 370 min (end) of the simulated working activity of both the control and intervention day
Muscle fatigue: Change of muscle twitch
3-D muscle twitch acceleration pattern measured at the acromion
Time frame: Change between 30 min before the beginning of the simulated working activity and 30 min after the end of the simulated working activity of both the control and intervention day
Muscle fatigue: Change of dynamic force control accuracy
Force control accuracy (mean squared error between the produced force (N) and the target force (N)) in an isometric dynamic tracking task
Time frame: Change between 30 min before the beginning of the simulated working activity and 30 min after the end of the simulated working activity of both the control and intervention day
EMG profile recorded by a single bipolar electrode: Static activity
p10 (level of the 10th percentile of the trapezius muscle activity) as an indicator of static activity primarily associated with continuous activity of the same pool of motor units.
Time frame: Continuously from the beginning to 370 min (end) of the simulated working activity of both the control and intervention day
Spatio-temporal distribution of EMG activity: Magnitude of activity
The spatio-temporal distribution of EMG activity is detected by a 2D array of electrodes (64 channels) and the following outcomes are determined: Magnitude of activity of muscle active regions (RMS sEMG).
Time frame: Continuously from the beginning to 370 min (end) of the simulated working activity of both the control and intervention day
Spatio-temporal distribution of EMG activity: Number of active epochs
The spatio-temporal distribution of EMG activity is detected by a 2D array of electrodes (64 channels) and the following outcomes are determined: Number of active epochs
Time frame: Continuously from the beginning to 370 min (end) of the simulated working activity of both the control and intervention day
Muscle fatigue: Change of static force control
Force control accuracy (mean squared error between the produced force (N) and the target force (N)) in isometric isotonic low level contraction
Time frame: Change between 30 min before the beginning of the simulated working activity and 30 min after the end of the simulated working activity of both the control and intervention day
Muscle fatigue: Change of force control in ramp contraction
Force control accuracy (mean squared error between the produced force (N) and the target force (N)) in isometric ramp contraction.
Time frame: Change between 30 min before the beginning of the simulated working activity and 30 min after the end of the simulated working activity of both the control and intervention day
Localized musculoskeletal discomfort
head-neck-shoulders-lower back-elbows-wrists-hip-upper legs-knees-ankles-feet-discomfort rated on 10 cm visual analog scales (adapted from Nordic questionnaire (Kuorinka et al 1987)
Time frame: At the start, and 70min, 130min, 190min, 310min, 370 min after the beginning of the simulated working activity of both the control and intervention day
Visual and general fatigue
10 cm visual analog scales
Time frame: At the start, and 70min, 130min, 190min, 310min, 370 min after the beginning of the simulated working activity of both the control and intervention day
Effort
6-20 Borg scale (6= no effort, 20=maximal possible effort)
Time frame: At the start, and 70min, 130min, 190min, 310min, 370 min after the beginning of the simulated working activity of both the control and intervention day
EMG profile recorded by a single bipolar electrode: Dynamic activity
p90 (level of the 90th percentile of the trapezius muscle activity) as an indicator of dynamic activity which may promote variability in the recruitment of motor units
Time frame: Continuously from the beginning to 370 min (end) of the simulated working activity of both the control and intervention day
Spatio-temporal distribution of EMG activity: Centroid of active regions
The spatio-temporal distribution of EMG activity is detected by a 2D array of electrodes (64 channels) and the following outcomes are determined: Centroid of active regions
Time frame: Continuously from the beginning to 370 min (end) of the simulated working activity of both the control and intervention day
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Swiss Federal Institute of Technology