Muscle fatigue based evaluation of bicycle design

Variability of Time- and Frequency-Domain Surface Electromyographic Measures in Non-Fatigued Shoulder Muscles

OCCUPATIONAL APPLICATIONSLocalized Muscle Fatigue (LMF) can be monitored or predicted based on the relative change in the values of surface electromyography (sEMG) measures with respect to the "fresh" or no-fatigue condition. Quantification of LMF based on relative change, though, relies on the assumption that the sEMG measures recorded in a no-fatigue condition can serve as an appropriate reference. Results of this study indicate that sEMG measures in a no-fatigue condition are affected by various work-related factors and provide further guidance on the variability of commonly used time- and frequency-domain sEMG measures to assist the ergonomist in improving the accuracy of LMF assessment.

The effect of low back pain on neuromuscular control in cyclists

This study was designed to identify neuromuscular adaptations of low back pain (LBP) cyclists , and the impact of a cycling effort on spinal shrinkage. Forty-eight trained cyclists rode their road bike on a smart trainer for 1-hour. Surface electromyography (EMG) recorded muscle activity of the lumbar erector spinae (LES), 3D motion analysis system recorded kinematic of the trunk, and stadiometry measured spinal height. Statistical comparisons were made using repeated measure ANOVAs. The LBP group presented increase in pain levels throughout the effort (p < 0.001). A significant group difference was only observed for the thoracic angle (p = 0.03), which was less flexed for LBP. The one-hour cycling effort (time effect) significantly increased the trunk flexion (p < 0.001) and thoracic flexion (p < 0.001) for both groups. Significant lower LES activation (35% less) was observed at the end of the effort  as well as a decrease in spinal height (p = 0.01) for both groups. Neuromuscular adaptations to cycling effort is identified by a decrease in LES EMG amplitude and an increase flexion of the trunk. Adaptation to pain is seen by an increase in thoracic flexion. Despite these adaptations, LBP cyclists could not ride their bike pain-free.

Multimodal Instrumentations as Fatigue Detection Using Fuzzy Logic Method

Fatigue is a condition experienced by a person that causes a decrease in a person's vitality and productivity. Fatigue can be characterized by slowed reaction time and fatigue. People’s condition is a significant factor in driving safety. Based on this increase in the number of accidents according to the Central Statistics Agency (BPS), experts conducted research on detecting fatigue that often occurs. In this study, a system that can detect fatigue is developed using parameters obtained from physiological indicators such as heart signals by using the Low Frequency/High Frequency ratio parameter, muscle signals using the average frequency domain of the muscle signal and oxygen saturation. The detection tool in this study uses the ECG Click Module, EMG Click Module, and Oximeter Click which will be connected to the ARM microcontroller, namely STM32F407ZG. The parameters that have been obtained are processed using the Fuzzy Logic method to determine the level of fatigue. Based on the tests results carried out on three subjects, parameter values were obtained where in the subject the three parameters entered into fuzzy logic, it was found that the three subjects were detected in a fairly tired state. The aggregated output that found from subject A was 0.6303, the aggregated output of subject B was 0.77948, and the aggregated output of subject C was 0.79188. Furthermore for future research development, the signal processing can be done more complex, besides that signal processing and fuzzy logic processing can be embedded so the process runs in realtime.

Upper Body Posture and Muscle Activation in Recreational Cyclists: Immediate Effects of Variable Cycling Setups

Purpose: Discomfort during cycling can be counteracted by adjusting the seat position. However, the influence of changes in cycling position regarding quantitative biomechanical adaptions of the upper body in recreational cyclists is unclear. This study aims to investigate the effects of saddle position and reach distance on upper body kinematics and muscle activation. Methods: Twelve recreational cyclists were investigated in four different sitting positions on an adjustable cycle trainer. Trunk, pelvis, shoulder, elbow and spinal kinematics as well as lower back and elbow extensor activity were analyzed for combinations of normal and shortened reach distance including horizontal and 10° downward inclined saddle positions. Results: An inclined saddle increased activation of elbow extensors by almost 23 ± 8% (p < .01) while a shortened reach distance resulted in a more posterior pelvic tilt of up to 18 ± 2% (p < .01) and less trunk forward lean of 10 ± 9% (p < .01). Shoulder flexion reduced by up to 23 ± 16% (p < .05) while elbow flexion increased by 15 ± 22% (p < .05) with a shortened reach distance. No differences between configurations were found for spinal kinematics and lower back muscle activity. Conclusions: Changing the reach distance showed considerable biomechanical effects on upper body kinematics of the pelvis and trunk rather than on the spine or on lower back muscle activity. For reach distance, most compensation of postural changes of the upper body occurred by changes of shoulder and elbow angles while elbow extensor activation was only altered by saddle downward inclination.

Applying systems ergonomics methods in sport: A systematic review

INTRODUCTION

As sports systems become increasingly more complex, competitive, and technology-centric, there is a greater need for systems ergonomics methods to consider the performance, health, and safety of athletes in context with the wider settings in which they operate. Therefore, the purpose of this systematic review was to identify and critically evaluate studies which have applied a systems ergonomics research approach in the context of sports performance and injury management.

MATERIAL AND METHODS

Five databases (PubMed, Scopus, ScienceDirect, Web of Science, and SPORTDiscus) were searched for the dates 01 January 1990 to 01 August 2017, inclusive, for original peer-reviewed journal articles and conference papers. Reported analyses were underpinned by a recognised systems ergonomics method, and study aims were related to the optimisation of sports performance (e.g. communication, playing style, technique, tactics, or equipment), and/or the management of sports injury (i.e. identification, prevention, or treatment).

RESULTS

A total of seven articles were identified. Two articles were focussed on understanding and optimising sports performance, whereas five examined sports injury management. The methods used were the Event Analysis of Systemic Teamwork, Cognitive Work Analysis (the Work Domain Analysis Abstraction Hierarchy), Rasmussen's Risk Management Framework, and the Systems Theoretic Accident Model and Processes method. The individual sport application was distance running, whereas the team sports contexts examined were cycling, football, Australian Football League, and rugby union.

CONCLUSIONS

The included systems ergonomics applications were highly flexible, covering both amateur and elite sports contexts. The studies were rated as valuable, providing descriptions of injury controls and causation, the factors influencing injury management, the allocation of responsibilities for injury prevention, as well as the factors and their interactions underpinning sports performance. Implications and future directions for research are described.

Relationship Between Body Positioning, Muscle Activity, and Spinal Kinematics in Cyclists With and Without Low Back Pain: A Systematic Review

Context:

Low back pain is reported by more than half of cyclists. The pathomechanics and association of risk factors of lumbar spine overuse injuries in cycling are not clearly understood.

Objective:

To determine whether relationships exist between body positioning, spinal kinematics, and muscle activity in active cyclists with nontraumatic low back pain.

Data Sources:

In August of 2015 and April of 2016, a comprehensive search of the PubMed, CINAHL, Ovid MEDLINE, and Scopus databases was performed independently by 5 reviewers.

Study Selection:

Included articles consisted of biomechanical studies examining factors relating to low back pain in cyclists as agreed upon by group consensus.

Study Design:

Systematic review.

Level of Evidence:

Level 4.

Data Extraction:

Five reviewers appraised by consensus each article using the Downs and Black checklist.

Results:

Eight studies met criteria for this review. There is evidence that cyclists with lower handlebar heights displayed increased lumbosacral flexion angles during cycling. Core muscle activation imbalances, back extensor endurance deficits, and increased lumbar flexion while cycling were found to be present in cyclists with low back pain.

Conclusion:

Spinal and core muscle activation imbalances in a prolonged flexed posture associated with cycling may lead to maladaptive spinal kinematics and increased spinal stresses contributing to overuse low back pain.

Effect of bike-fit in the perception of comfort, fatigue and pain

The aim of this study was to assess the influence of different bike positions on the perception of fatigue, pain and comfort. Twenty cyclists underwent three tests that involved cycling for 45 min at their individual 50% peak aerobic power output while adopting different positions on the bike. Participants performed the cycling tests adopting three positions defined by two parameters (knee flexion angle [20°, 30°, 40°] and trunk flexion angle [35°, 45°, 55°]) in random order. Angles were measured using a 2D motion analysis system during cycling and applying Fonda's correction factor. Perceptions of comfort, fatigue and pain were reported before the end of each test. The combination of 40° knee flexion and 35° trunk flexion was perceived as the most uncomfortable position. Moreover, greater knee flexion had a negative effect on trunk comfort, accompanied by greater levels of fatigue and pain perception in the anterior part of the thigh and knee. In conclusion, cyclists perceived the most comfortable position to be when the saddle height was within the recommended knee angle (30° calculated from the offset position or 40 ± 4.0° of absolute value). Upright trunk was found to be the most comfortable position for recreational cyclists, where aerodynamics is not so important. Cyclists' bike perceptions should be taken into account when it comes to choosing the most beneficial position, since this can play a role in injury prevention and enhance cycling performance.

A real-time fatigue monitoring and analysis system for lower extremity muscles with cycling movement

A real-time muscle fatigue monitoring system was developed to quantitatively detect the muscle fatigue of subjects during cycling movement, where a fatigue progression measure (FPM) was built-in. During the cycling movement, the electromyogram (EMG) signals of the vastus lateralis and gastrocnemius muscles in one leg as well as cycling speed are synchronously measured in a real-time fashion. In addition, the heart rate (HR) and the Borg rating of perceived exertion scale value are recorded per minute. Using the EMG signals, the electrical activity and median frequency (MF) are calculated per cycle. Moreover, the updated FPM, based on the percentage of reduced MF counts during cycling movement, is calculated to measure the onset time and the progressive process of muscle fatigue. To demonstrate the performance of our system, five young healthy subjects were recruited. Each subject was asked to maintain a fixed speed of 60 RPM, as best he/she could, under a constant load during the pedaling. When the speed reached 20 RPM or the HR reached the maximal training HR, the experiment was then terminated immediately. The experimental results show that the proposed system may provide an on-line fatigue monitoring and analysis for the lower extremity muscles during cycling movement.

Assessment of early onset of driver fatigue using multimodal fatigue measures in a static simulator

Driver fatigue is an important contributor to road accidents. This paper reports a study that evaluated driver fatigue using multimodal fatigue measures, i.e., surface electromyography (sEMG), electroencephalography (EEG), seat interface pressure, blood pressure, heart rate and oxygen saturation level. Twenty male participants volunteered in this study by performing 60 min of driving on a static simulator. Results from sEMG showed significant physical fatigue (ρ < 0.05) in back and shoulder muscle groups. EEG showed significant (ρ < 0.05) increase of alpha and theta activities and a significant decrease of beta activity during monotonous driving. Results also showed significant change in bilateral pressure distribution on thigh and buttocks region during the study. These findings demonstrate the use of multimodal measures to assess early onset of fatigue. This will help us understand the influence of physical and mental fatigue on driver during monotonous driving.