Investigation of supraspinatus muscle architecture following concentric and eccentric training

• Published in: Journal of science and medicine in sport 2015-07, Vol.18 (4), p.378-382
• Main Authors: Kim, Soo Y, Ko, Jong Bum, Farthing, Jonathan P, Butcher, Scotty J
• Format: Article
• Language: English
• Subjects: Adult; Data collection; Exercise; Female; Fiber bundle; Humans; Isometric Contraction; Load; Male; Muscle Strength; Organ Size; Physical Medicine and Rehabilitation; Rehabilitation; Resistance Training - methods; Rotator cuff; Rotator Cuff - anatomy & histology; Rotator Cuff - diagnostic imaging; Rotator Cuff - physiology; Shoulder; Sports Medicine; Sports training; Studies; Torque; Ultrasonic imaging; Ultrasonography; Weightlifting; Young Adult
• ISSN: 1440-2440; 1878-1861
• DOI: 10.1016/j.jsams.2014.05.007

Abstract Objectives To investigate the effects of concentric or eccentric abduction strength training on supraspinatus fiber bundle architecture and strength. Design A pre–post single-subject design. Methods Thirteen participants were randomized to concentric ( n = 6) or eccentric ( n = 7) training groups. Participants completed an eight week shoulder abduction training program in the scapular plane using an isokinetic dynamometer. Resistance training, requiring maximal effort on contraction, consisted of 4 sets of 8 reps at 60°/s in weeks 1–4, and 6 sets of 6 reps at 60°/s in weeks 5–8 with a frequency of 3×/week. Primary outcome measures included fiber bundle length, pennation angle, and muscle thickness of supraspinatus and these were quantified using ultrasound. Secondary outcome measures included isometric, eccentric and concentric abduction strength and these were evaluated using the isokinetic dynamometer. Results Mean fiber bundle length in the relaxed ( p = 0.033) and contracted ( p = 0.036) states significantly decreased with concentric training but remained unchanged with eccentric training. A significant increase in pennation angle, muscle thickness, and peak torque were found with training but no significant differences were detected between concentric and eccentric groups. Conclusions Training mode has a significant impact on fiber bundle length changes of the supraspinatus. Eccentric training of shoulder abduction leads to similar strength gains as concentric, but it may also have the added advantages of maintaining fiber bundle lengths and promoting tendon healing. Study is needed to confirm fiber bundle changes in a clinical population which would further support the use of eccentric abduction strength training in rehabilitation settings.