"I made this one underarm throw, and that's when it all started. Since then, it has been painful more or less every time I throw."
In contrast to deceleration-related problems, players with acceleration-related pain often experience a specific onset, typically during a throw. However, these injuries sometimes occur when the player tries to prevent a breakthrough or if they are blocked during a throw. The pain typically occurs during the late cocking and acceleration phase, which is why players often struggle with high-velocity throws.
Mechanisms
These types of injuries are often located in the muscle-tendon junctions of strong internal rotators such as the teres major, subscapularis, and latissimus dorsi. These muscles are highly active during the late cocking to acceleration phase of a throw and play a significant role in generating throwing velocity, especially during a typical "whip throw" where the player executes a high-speed external-to-internal rotation. This is the main reason why players often feel weak and have trouble with high-velocity throws when they have an ecceleration related problem. These types of injuries can also occur when playing defense, particularly when the player tries to block a shot or stop a breakthrough, or if the player fall and lands with an outstretched arm..
Assessment
Assessing internal rotation strength is key to diagnosing this condition, and this should be done objectively using a handheld dynamometer. Strength should be tested in three different positions: (1) in a flexion/horizontal adduction/internal rotation position (similar to a Hawkins-Kennedy position but with isometric internal rotation); (2) in a neutral position, such as the "belly press test"; and (3) in shoulder extension with internal rotation, such as the internal rotation lag sign. Bear in mind that in the acute phase some of the end range position could be too painful but often the Belly press test is feasible.
Passive range of motion (ROM) should be tested in all directions with the athlete in a supine position. Flexion, abduction, external rotation, and/or horizontal abduction often reproduce the athlete's symptoms.
Imaging (ultrasound or MRI) is recommended when suspecting anything beyond minor injuries. The imaging should include not only the rotator cuff but also the latissimus dorsi and teres major, as these muscles are often overlooked.
Management
In contrast to deceleration-related problems, acceleration-related problems often involve muscle, muscle-tendon, or tendon injuries, which require tissue healing. The healing process and time vary depending on the tissue involved. In my experience, an injury that only involves muscle fibers tends to heal more quickly compared to an intramuscular tendon injury, which in turn often heals faster than a purely tendon injury. Low- and moderate-grade ruptures are treated conservatively with a good prognosis, although full recovery may take up to 6 months. For high-grade and full-thickness ruptures, imaging and surgical consultation are required.
In the initial phase, the athlete should be informed and educated about the injury, healing time, and prognosis. Active ROM exercises can be used to initiate strengthening during this phase. Start with active ER exercises, beginning with 0° abduction and then gradually increasing abduction to 90°. The next step is isometric contractions, initially within the inner ROM. This can be done with the belly press test, which serves both as a diagnostic test and as an exercise. Progress from this position to the bear hug position. Muscle contraction in this phase is crucial for facilitating tissue healing; however, it needs to be balanced and should remain pain-free to avoid setbacks and the risk of re-injury. This phase also includes strengthening and control exercises for the posterior cuff, such as external rotations and scapular retractions, which can often be included early in rehabilitation.
Once full ROM is recovered and daily activities, along with isometric strengthening, are asymptomatic, you can move on to the intermediate phase. This phase includes dynamic contractions, initially within the inner ROM and eventually progressing to full ROM. For the subscapularis, this can be done using diagonal flexion pattern exercises, starting from a throwing position and finishing in a belly press position. For the teres major and latissimus dorsi, a single-arm lat pulldown can serve as a full ROM exercise. In the final phase, stretch-shortening cycle exercises are introduced, initially within the inner ROM positions.
Summary
Acceleration-related shoulder injuries can be frustrating and challenging, but with a well-structured rehabilitation program, most athletes can expect a full recovery. The key is to follow a progressive loading protocol and remain patient throughout the process. Remember that each injury is unique, and recovery times can vary depending on the extent of the injury and the individual’s adherence to the rehab plan.
In the next part of this series, we'll delve into inside impingement and biceps-related problems—two other relatively common issues that can affect overhead athletes.
These conditions can present their own set of challenges, but understanding their mechanisms and management strategies will help guide you or your athletes back to peak performance.