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Designing for Upper Torso and Arm Anatomy
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
The clavicle articulates distally with the acromion of the scapula at the acromioclavicularjoint, a synovial gliding joint. The acromion is the bony upper shelf of the scapula that sits above the humeral head of the upper arm. You can palpate it as a ridge about 2 cm (.8 in.) in length—the size varies person to person. The acromial point, the lateral tip of the acromion, is an often-used landmark spot to position wearable product features. For example, the acromial point corresponds to the top point of the cap of a set-in sleeve (Figure 4.18).
How does multi-set high-load resistance exercise impact neuromuscular function in normoxia and hypoxia?
Published in European Journal of Sport Science, 2023
N. Benjanuvatra, D. Bradbury, G. Landers, P. S. R. Goods, O. Girard
Surface EMG activity of the pectoralis major, anterior deltoid and the lateral and medial heads of triceps brachii muscles was recorded with surface electrodes (Cleartrace, 1700-050, Conmed., Utica, NY, USA) at an interelectrode distance of 20 mm on the participant’s dominant side. Before placing the electrodes, the overlying skin was carefully prepared (any hair was shaved, the skin lightly abraded with scourers and cleaned with alcohol wipes). Electrode placement followed recommendations from the Anatomical Guide for the Electromyographer (Perotto & Delagi, 2005). Electrodes were placed while the participant was in a standing position. For the pectoralis major muscle, the electrodes were placed over the anterior axillary fold level with the sternocostal portion of the muscle. For the anterior deltoid muscle, the electrodes were placed 6 cm below the anterior margin of the acromion. For the lateral head of triceps brachii muscle, the electrodes were placed immediately posterior to the deltoid tuberosity. For the medial head of triceps brachii muscle, the electrode were placed 6 cm proximal to the medial epicondyle of the humerus. Electrodes were fixed length-wise, over the middle of the muscle bellies. The electrodes were taped down with cotton wool swabs to minimise sweat-induced interference. The EMG reference electrode was placed over the sternal end of the clavicle, also on the subjects’ dominant side. To minimise movement artefact, wires between the electrodes and the EMG unit were secured to the skin with adhesive tape.
Critical scapula motions for preventing subacromial impingement in fully-tethered front-crawl swimming
Published in Sports Biomechanics, 2022
Since the error in the measurement of scapular motion was reported to increase when the arm was elevated high (Karduna, McClure, Michener, & Sennett, 2001; Konda, Yanai, & Sakurai, 2011; Meskers, van de Sande, & de Groot, 2007), we adopted two approaches to minimise this error. The first was the use of a mini sensor (RX1-C, 23 mm×13 mm×11 mm, half of the size of a standard sensor) for each scapula. The flat superior surface of the acromion was narrow and a small sensor was stabilised better than the standard sensor and was less affected by the displacement of the Deltoid muscles. The second was a careful judgment on the attachment site. According to the study conducted by Konda et al. (2011) as well as our experience, the sensor on the acromion would be translated and/or rotated by the displacement of the Deltoid muscles when the arm elevation angle was high. We put the sensor on the proximal part of the acromion near the spine of scapula and confirmed for each participant that the sensor was not rotated by the displacement of the Deltoid muscles during several times of arm abduction.
A physiological and biomechanical investigation of three passive upper-extremity exoskeletons during simulated overhead work
Published in Ergonomics, 2022
Eric B. Weston, Mina Alizadeh, Hamed Hani, Gregory G. Knapik, Reid A. Souchereau, William S. Marras
Subjects were prepared with surface electrodes on the aforementioned 10 torso muscles in accordance with standard placement guidelines (Mirka and Marras 1993) and 41 reflective motion capture markers placed in accordance with a custom full-body marker set prescribed by OptiTrack’s motion capture software. Finally, NIRS optodes were placed into secure holders and secured to the skin on top of the muscle bellies of each subject’s right and left trapezius and anterior deltoid muscles using double-sided adhesive tape. For the trapezius, optodes were placed halfway along the line extending between the vertebra prominens and the acromion process of the scapula. For the anterior deltoid, a point two thirds the distance between the clavicular notch and acromion process was first located, and optodes were placed one third the distance between this point and the olecranon process of the ulna. After sensor placement was complete, the biomechanical model was calibrated using data derived from a series of dynamic concentric and eccentric lumbar motions while holding a 9.07kg medicine ball. This calibration technique has been described previously (Dufour, Marras, and Knapik 2013).