Exploring the Effects of Cognitive Load on Muscle Activation during Functional Upper Extremity Tasks

Author(s):  
D. E. Nathan ◽  
D. C. Jeutter
2014 ◽  
Vol 49 (3) ◽  
pp. 317-321 ◽  
Author(s):  
Yen-Po Huang ◽  
You-Li Chou ◽  
Feng-Chun Chen ◽  
Rong-Tyai Wang ◽  
Ming-Jer Huang ◽  
...  

Context: Bench-press exercises are among the most common form of training exercise for the upper extremity because they yield a notable improvement in both muscle strength and muscle endurance. The literature contains various investigations into the effects of different bench-press positions on the degree of muscle activation. However, the effects of fatigue on the muscular performance and kinetics of the elbow joint are not understood fully. Objective: To investigate the effects of fatigue on the kinetics and myodynamic performance of the elbow joint in bench-press training. Design: Controlled laboratory study. Setting: Motion research laboratory. Patients or Other Participants: A total of 18 physically healthy male students (age = 19.6 ± 0.8 years, height = 168.7 ± 5.5 cm, mass = 69.6 ± 8.6 kg) participated in the investigation. All participants were right-hand dominant, and none had a history of upper extremity injuries or disorders. Intervention(s): Participants performed bench-press training until fatigued. Main Outcome Measure(s): Maximal possible number of repetitions, cycle time, myodynamic decline rate, elbow-joint force, and elbow-joint moment. Results: We observed a difference in cycle time in the initial (2.1 ± 0.42 seconds) and fatigue (2.58 ± 0.46 seconds) stages of the bench-press exercise (P = .04). As the participants fatigued, we observed an increase in the medial-lateral force (P = .03) and internal-external moment (P ≤ .04) acting on the elbow joint. Moreover, a reduction in the elbow muscle strength was observed in the elbow extension-flexion (P ≤ .003) and forearm supination-pronation (P ≤ .001) conditions. Conclusions: The results suggest that performing bench-press exercises to the point of fatigue increases elbow-joint loading and may further increase the risk of injury. Therefore, when clinicians design bench-press exercise regimens for general athletic training, muscle strengthening, or physical rehabilitation, they should control carefully the maximal number of repetitions.


2014 ◽  
Vol 46 ◽  
pp. 669
Author(s):  
Amanda Mitchell ◽  
Julie Ralston ◽  
George Davies ◽  
Bryan L. Riemann

Author(s):  
Yujin Kwon ◽  
Gwanseob Shin

The muscular loads of the upper extremity and chest muscles were assessed during floor vacuuming with stick vacuum cleaners. Ten participants conducted vacuuming with two stick cleaners (weight: 3.03 kg, 3.56 kg) on tiled and carpeted floors while the myoelectric activity of the upper extremity and chest muscles were collected. The mean muscle activation levels ranged from 15.5% to 45.7% of the maximum voluntary capacity. Greater muscular loads were observed on the forearm and shoulder muscles when vacuuming with repeated curved strokes (vs. straight storkes), and on the chest muscle when vacuuming the carpeted floor. The range of muscular loads were higher than that of occupational tasks such as house painting and dental drilling, which have been known as intensive activities for upper extremities. The results suggest that floor vacuuming with stick vacuum cleaners is physically demanding for household consumers. Ergonomic interventions such as more user-friendly design should be considered.


2014 ◽  
Vol 95 (9) ◽  
pp. 1731-1741 ◽  
Author(s):  
Arjen Bergsma ◽  
Alessio Murgia ◽  
Edith H. Cup ◽  
Paul P. Verstegen ◽  
Kenneth Meijer ◽  
...  

Ergonomics ◽  
2009 ◽  
Vol 52 (9) ◽  
pp. 1144-1152 ◽  
Author(s):  
Martin P.H. Smets ◽  
James R. Potvin ◽  
Peter J. Keir

2007 ◽  
Vol 118 (1) ◽  
pp. 164-176 ◽  
Author(s):  
Joanne M. Wagner ◽  
Alexander W. Dromerick ◽  
Shirley A. Sahrmann ◽  
Catherine E. Lang

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