Avoiding high‐risk rotator cuff loading: Muscle force during three pull‐up techniques

Abstract

Heavily loaded overhead training tasks, such as pull-ups are an effective strength training and rehabilitation exercise requiring high muscle forces maintained over a large range of motion. This study used experiments and computational modeling to examine loading patterns during three different pull-up variants and highlighted risks to vulnerable musculoskeletal structures. Optical motion tracking and a force platform captured kinematics and kinetics of 11 male subjects with no history of shoulder pathology, during performance of three pull-up variants-pronated front grip, pronated wide grip, and supinated reverse grip. UK National Shoulder model (UKNSM) simulated biomechanics of the shoulder girdle. Muscle forces and activation patterns were analyzed by repeated measures ANOVA with post-hoc comparisons. Motor group recruitment was similar across all pull-up techniques, with upper limb depression occurring secondary to torso elevation. Stress-time profiles show significant differences in individual muscle patterns among the three pullup variants, with the most marked differences between wide grip and reverse grip. Comparing across techniques, latissimus dorsi was relatively more active in wide pull-ups (P < .01); front pull-ups favored activation of biceps brachii and brachialis (P < .02); reverse pull-ups displayed higher proportional rotator cuff activation (P < .01). Pull-ups promote stability of the shoulder girdle and activation of scapula stabilizers and performing pull-ups over their full range of motion is important as different techniques and phases emphasize different muscles. Shoulder rehabilitation and strength & conditioning programs should encourage incorporation of all three pull-up variants with systematic progression to provide greater global strengthening of the torso and upper limb musculature. K E Y W O R D S athletic training, biomechanics, motion analysis, musculoskeletal modeling, rehabilitation, shoulder 2206 | URBANCZYK et Al. CONFLICTS OF INTEREST The authors declare that no financial or personal relationships with people or organizations have inappropriately influenced this work and that the results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Exercise Selection and Common Injuries in Fitness Centers: A Systematic Integrative Review and Practical Recommendations

“…The susceptibility of the shoulder complex to RT-related injuries is due in part to the stress placed on a joint that is anatomically non-load-bearing but assumes the role of an active joint with high-load repetitive lifting [42]. For example, impingement injuries are possible when the subacromial space is at its smallest, at 120 • humeral elevation, 90 • abduction, and 45 • external rotation [65]. This position is reached during the pull-up motion (when supraspinatus is most active), especially with a narrow grip such as during front and reverse pull-ups (since it increases the required abduction moment).…”

“…This position is reached during the pull-up motion (when supraspinatus is most active), especially with a narrow grip such as during front and reverse pull-ups (since it increases the required abduction moment). Nevertheless, wide pull-ups reduce the high stresses in both the deltoid and supraspinatus by emphasizing the back muscles (i.e., latissimus dorsi, trapezius, and rhomboid major) [65]. It is noteworthy that the injury risk might be higher when the fatigue level rises due to the increased eccentric loading on the supraspinatus.…”

The influence of closed or open grip type during a pull-up test to exhaustion

“…During the pull-up exercise, there are substantial differences in muscle activation when the width between hands or the forearm orientation (intended according to supinated or pronated pull-ups) changes. In fact, differences are present both for a smaller bending of the elbow and for the different working planes of the humerus [1,11,22]. Urbanczyk et al [22] reported that during wide pull-ups the latissimus dorsi was more active than in pronated shoulder width pull-ups (in which biceps brachii and brachialis activation was prevalent) and supinated pull-ups (in which rotator cuff activation was prevalent).…”

“…In fact, differences are present both for a smaller bending of the elbow and for the different working planes of the humerus [1,11,22]. Urbanczyk et al [22] reported that during wide pull-ups the latissimus dorsi was more active than in pronated shoulder width pull-ups (in which biceps brachii and brachialis activation was prevalent) and supinated pull-ups (in which rotator cuff activation was prevalent). Lusk et al [11] found that wide-width lat pull-down did not significantly influence the latissimus dorsi activation, which seems to be more active with a pronated than a supinated grip, although analysed during lat pull-down exercise (performed using a lat machine).…”

“…Military admission tests, for example, present physical challenges in which it is necessary to perform a minimum number of repetitions of bodyweight exercises, with more points attributed to a higher number of repetitions [4,12,13]. Bar pull-ups are usually included within those tests, and represent an exercise requiring high strength levels [22]. All these pullup tests present indications regarding the orientation of the hand (overhand -pronated) and their distance [16], the passing of the chin during the ascending phase and the full extension of the upper limbs in the descending phase (as stated by the International Physical Fitness Test (IPFT) guidelines [25] and the Italian military test rules [13]).…”