Latissimus Dorsi Strains in Baseball Throwers: A Critical Guide to Diagnosis, Treatment, and Return to Sport

In the world of baseball—especially among high-velocity pitchers—latissimus dorsi (lat) strains have emerged as a growing source of shoulder pain and missed playing time. Once considered rare, advances in diagnostic imaging and an emphasis on performance metrics have spotlighted the importance of the lat in the throwing motion. Understanding this injury is key to achieving a safe and successful return to the mound.

Frequency and Risk Factors in Baseball
Recent studies estimate that latissimus dorsi and teres major injuries account for approximately 2–5% of all throwing-related injuries in professional baseball (Ahmad et al., 2018). While less common than UCL injuries or rotator cuff strains, lat strains often lead to significant time lost:

• Average MLB time missed per lat/teres injury: 60–80 days (Erickson et al., 2019)
• Higher rates among starting pitchers due to repetitive high-load throwing

Risk factors include:

• High pitch velocity (≥90 mph)
• Inadequate trunk and scapular strength
• Poor deceleration mechanics
• Overuse without proper rest and recovery periods

What Is a Latissimus Dorsi Strain?
The latissimus dorsi is a broad, powerful muscle that originates from the lower spine and pelvis and inserts onto the humerus (upper arm bone). It plays a vital role in:

• Arm extension
• Internal rotation
• Adduction
• Forceful deceleration of the arm after ball release

A lat strain typically occurs during the late cocking or acceleration phase of pitching when the arm is under extreme stress.

The strain can involve:

• Muscle belly
• Musculotendinous junction
• Tendon near the humeral insertion
  

Signs and Symptoms
Athletes with a lat strain often describe:

• Sudden, sharp or pulling pain in the back of the shoulder, below the scapula
• Pain during arm extension or deceleration
• Weakness with throwing or pulling motions
• Tenderness along the posterior axilla (armpit)
• Visible bruising in moderate to severe cases
• Decreased throwing velocity or early arm fatigue

Early symptoms are sometimes misdiagnosed as rotator cuff or posterior capsule injuries, highlighting the importance of an accurate clinical assessment.

Diagnosis and Imaging
A combination of clinical exam and imaging is essential:

• Palpation along the posterior shoulder and axillary fold
• Resisted shoulder extension and internal rotation testing reproduce pain
• MRI with specific latissimus and teres imaging sequences confirms diagnosis, grading severity (Grade I–III)

Ultrasound can also be helpful for dynamic assessment in experienced hands.

Treatment Options
Treatment is almost always non-surgical for partial strains.

Phase 1: Acute Management (0–10 Days)

• Rest from throwing and overhead activitiesIce and anti-inflammatory measures
• Protect the shoulder with pain-free range of motion exercises for the scapula and trunk.

Phase 2: Controlled Mobility and Strengthening (2–4 Weeks)

• Progress to isometric latissimus strengthening (e.g., prone scapular sets, isometric pulls)
• Gentle core strengthening and posterior shoulder mobility work
• Initiate scapular stabilization drills

Phase 3: Functional Strengthening and Plyometrics (4–6 Weeks)

• Eccentric and concentric latissimus strengthening (e.g., resisted rows, banded pulls)
• Medicine ball rotational throws and overhead slams with controlled loading
• Address kinetic chain deficits (hips, thoracic spine, core)

Phase 4: Sport-Specific Progression (6–10+ Weeks)

• Graduated throwing program with careful monitoring of pain and mechanics
• Plyometric throwing drills before full bullpen or game scenarios

Return to Sport Timelines

• Grade I (mild strain): 4–6 weeks
• Grade II (moderate tear): 8–10 weeks
• Grade III (complete tear): 12+ weeks; surgical repair may be required but is rare

According to Erickson et al. (2019), 86% of professional baseball players returned to their pre-injury level of play following conservative management of lat/teres injuries.

However, those who returned too soon without full strength and mechanics restoration had higher recurrence rates and prolonged disability.

Risk of Recurrence and Prevention
Risk of recurrence stems from:

• Incomplete lat strength restoration
• Lack of trunk rotational control
• Return to throwing with altered mechanics (often subconsciously offloading the lat)

Prevention Strategies

• Rotational and deceleration strength training (e.g., anti-rotation core drills, eccentric lat pull-ins)
• Total body mobility maintenance, especially hips and thoracic spine
• Workload monitoring (pitch counts, recovery days)
• Emphasize proper deceleration mechanics during throwing
• Incorporate lat activation exercises into regular warm-ups

Summary
Latissimus dorsi strains, while less frequent than other throwing injuries, can be among the most disabling if not properly managed. With early diagnosis, structured rehab, and an emphasis on kinetic chain efficiency, baseball throwers can achieve full recovery—and potentially return even stronger than before.

Patience, precision, and progressive strength-building are the cornerstones of success.

References

• Ahmad CS, et al. (2018). Latissimus dorsi and teres major injuries in professional baseball pitchers: A review. Journal of the American Academy of Orthopaedic Surgeons, 26(2): 59–65.
• Erickson BJ, et al. (2019). Latissimus dorsi and teres major tears in Major League Baseball pitchers: Return to play and performance analysis. Orthopaedic Journal of Sports Medicine, 7(8): 2325967119862641.
• Aoki M, et al. (2004). Latissimus dorsi transfer for irreparable rotator cuff tears: A biomechanical study. Journal of Shoulder and Elbow Surgery, 13(6): 611–615.
• Schickendantz MS, et al. (2009). Shoulder injuries in the overhead athlete: The role of the latissimus dorsi and teres major muscles. Clinics in Sports Medicine, 28(4): 619–628.
• Camp CL, et al. (2018). Epidemiology and impact of latissimus dorsi and teres major injuries in professional baseball pitchers. American Journal of Sports Medicine, 46(7): 1720–1726.