This article is part two of a two-part series. Read “Part One - The Muscles” for a look at baseball injury statistics, mechanisms of injury and a beginner exercise program for baseball players.
How can arm injuries be linked to the hips? How does the performance of the core have a say in the performance of the shoulder? The body is full of dynamic interconnected movements, and for that we can thank the kinetic chain. The kinetic chain is the idea that joints and body segments affect one another during movement: when one part of the body is in motion, it affects the movement of neighboring body parts, all the way from one end of the body to the other.1
The kinetic chain can be both a friend and a foe to baseball players. When the body is moving correctly, baseball players can expect elevated performance, less pain and less injury. When the kinetic chain is disrupted, however, baseball players experience pain, acute or chronic injuries and diminished performance. Baseball is comprised of many movements that rely on the kinetic chain, like throwing, swinging a bat, catching and pitching. However, for the sake of in-depth analysis, we’ll focus on the pitching movement; after all, we know that pitchers experience 75% of the total injuries in baseball today.2
A Quick Review of Baseball Mechanisms of Injury
In part one, we covered some key facts about injuries in baseball: primarily that non-contact injuries, or disruptions in the kinetic chain that cause musculoskeletal injury, account for 41.5% of injuries in games and 63.9% of injuries in practices.3 These injuries can be the result of:
- Poor mechanics
- Weakness
- Year-round baseball, or not enough rest
- Single-sport specialization
To complement this data, we suggested that the shoulder, scapula, legs/hip and core were the primary strengthening components that yield baseball performance success, especially for pitchers. But why?
Activity of the Kinetic Chain During Each Phase of the Pitching Movement
Reviewing each phase of the pitch, you can see that these four muscles or muscle groups work in a coordinated effort. Let’s break them down to better understand the components of the kinetic chain and how they can help or hinder the pitching motion.
Phase 1: The Windup
- Contralateral lower extremity, elevation of lead leg to its highest point
- Center of gravity over his back leg
- POTENTIAL KINETIC CHAIN DISRUPTION: Early forward motion of the hips and leg can result in additional force needed from the shoulder to complete the pitch.4
Phase 2: Early Cocking (Stride)
- Pelvic tilt and rotation
- Shoulder abduct shoulder and externally rotated
- Lead foot makes contact with the ground
- POTENTIAL KINETIC CHAIN DISRUPTION: If the stride foot lands in a closed position with limited trunk rotation, pitcher must throw across body. If the stride food lands open with premature trunk rotation, shoulder will need to produce more force to complete the pitch.4
Phase 3: Late Cocking (Between Stride and Acceleration)
- Retracted scapula
- Humeral abduction and external rotation
- Supraspinatus in glenohumeral compression
- Pelvis reaches max rotation
- Torso produces angular velocity
- Subscapularis, pectoralis major and latissimus dorsi eccentrically contract for external rotation
- POTENTIAL KINETIC CHAIN DISRUPTIONS: Reduced external rotation cause the acceleration phase to happen over a shorter distance.4
Phase 3: Late Cocking (Between Stride and Acceleration)
- Scapula protracts
- Shift from eccentric to concentric anteriorly and posteriorly
- Humeral internal rotation
- Maximum elbow extension
- POTENTIAL KINETIC CHAIN DISRUPTIONS: Reduced forward trunk tilt will cause pitcher to throw upright, causing the acceleration phase to happen over a shorter distance. Increased flexion in the lead knee can also result in less torso force generation.4
Phase 5: Deceleration
- Scapula is stabilized by the trapezius, rhomboids and serratus anterior
- Posterior/inferior force on glenohumeral joint
- Eccentric loading of rotator cuff to resist distraction
- Eccentric biceps activation
- Not a common phase in which injuries occur.4
Phase 6: Follow Through
- Muscle firing decreases, but horizontal adduction increases to 60°
- Joint loading and force is so low at this point, injury is unlikely to occur. 4
The Need for Strength
As the exercise of breaking down the kinetic chain of the pitch shows, if something goes wrong with one of the muscles or movements, it’ll have a domino effect on the others. This is why properly strength training the most vital parts of the body is the best way for baseball players to rehabilitate injuries, prevent further injury and add longevity to their careers. Luckily, a sports medicine expert has crafted an advanced-level training program that covers all of these bases… literally.
The Advanced Throwers 10 Program: A Free Exercise Program to Enhance Baseball Performance
Dr. Kevin Wilk DPT, PT, FAPTA has been a world-renowned physical therapist for decades. As a leading authority in the rehabilitation of sports injuries and orthopedic lesions, he has dedicated his career to both healing and enhancing professional athletes, along with conducting years of laboratory research, biomechanical research and clinical outcome studies.
After his Throwers 10 Program became an evidence-based success,5,6,7 Dr. Wilk created the Advanced Throwers 10 program so baseball players could continue to improve strength, increase endurance and reduce injury at an elite level. This unique combination of advanced exercise techniques bridges the gap between rehabilitation and training and pairs perfectly with the TheraBand CLX Resistance Band. It facilitates a kinetic linking of the upper and lower extremities to provide a higher level of humeral head control necessary for the overhead throwing athlete to play a pain-free game or make a symptom-free return to sports.
Ready to get started? Check out the Advanced Throwers 10 Program videos and printable exercise guide below!
Watch the videos below to master the movements
Download our printable exercise guide to give your athletes a visual reminder of their exercise program
Resources:
- https://www.healthline.com/health/4-kinetic-chain-exercises
- https://www.ncbi.nlm.nih.gov/pubmed/21709023
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1941283/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3445080/
- Wilk KE, Andrews JR, Arrigo CA: Preventive & Rehabilitative Exercises for the Shoulder & Elbow. 6th Ed. Birmingham,AL American Sports Medicine Institute 1996
- https://www.ncbi.nlm.nih.gov/pubmed/22293772
- https://www.ncbi.nlm.nih.gov/pubmed/26972270