If you’re dedicated to staying fit and strong—whether you’re a weekend warrior, a regular gym-goer, or an aspiring athlete—understanding how your joints function can significantly enhance your workouts. One of the more nuanced (and often overlooked) concepts is knowing the difference between an open-pack and a closed-pack position. By learning what these terms mean and how they apply to the shoulder, hip, and elbow, you’ll be better equipped to optimize your training, reduce injury risks, and refine your performance.
Defining Open-Pack and Closed-Pack
In physiotherapy, the open-pack position (sometimes called the loose-pack position) refers to the joint angle at which the surrounding ligaments and joint capsule are relatively slack. At this angle, the two bone surfaces that make up the joint are not in full contact, and the joint itself has more freedom to move. Because of this slackness, open-pack positions are commonly used during manual therapy sessions to help improve range of motion or to assess the joint without excessive tension.
Closed-pack positions, on the other hand, represent the angles at which the ligaments and joint capsule are under maximum tension and the bones have the most contact. This generally makes the joint more stable, but it also creates more compressive forces. Although closed-pack positions can aid in generating power and stability—think of locking a joint out to secure a heavy lift—such stability comes with the trade-off of reduced flexibility, making these positions more prone to stress if used improperly or under sudden, unplanned loads.
Applying the Concept to the Shoulder
As one of the most mobile joints in the human body, the shoulder (glenohumeral joint) exhibits a very noticeable difference between its open-pack and closed-pack positions. In a closed-pack position, the shoulder is held in full abduction and external rotation. You can imagine throwing a ball or performing a maximal overhead stretch to get a sense of this fully “locked” position, which offers substantial stability but can be vulnerable to abrupt, forceful movements if form falters.
An open-pack shoulder, by contrast, is typically around 55 degrees of abduction and about 30 degrees of horizontal adduction. Physical therapists often rely on this more relaxed angle for shoulder mobilization, especially when helping someone with impingement or restricted range of motion. In a gym setting, you might notice that staying shy of a full overhead lockout—or gently reducing external rotation—can relieve stress on the capsule and reduce discomfort during overhead lifts. On the other hand, pressing movements such as bench press or push-ups, which don’t fully force the joint into a closed-pack position, may still lead to issues if technique and stability are neglected.
Understanding How This Plays Out in the Hip
The hip joint, unlike the shoulder, is built to withstand significant loads while offering a broad range of motion. You’ll find its closed-pack position when the hip is extended, slightly abducted, and internally rotated—a stance that can look and feel quite stable, such as the lockout at the top of a deadlift or a squat. Despite providing a firm sense of security, this locked stance places maximum tension on the joint capsule and surrounding ligaments. If you force the hips to bear sudden or extreme loads in this position without proper technique or muscular support, the risk of injury can creep up.
Its open-pack position is usually around 30 degrees of flexion, 30 degrees of abduction, and slight external rotation. You can think of a comfortable, relaxed, “frog-leg” position when lying on your back. Physical therapists often mobilize the hip in this angle to improve flexibility and alleviate joint-related discomfort. During training, you might notice open-pack angles at the bottom of a squat or during a hip hinge movement as you transition from one phase of the lift to another. Balancing both open-pack and closed-pack positions is crucial for healthy hip mechanics, which is why a well-designed strength program includes exercises that allow for safe, controlled movement throughout various angles rather than constantly training at a single end-range.
Spotlight on the Elbow
Although the elbow is a simpler hinge joint compared to the ball-and-socket nature of the shoulder and hip, it still follows the same principle of open- and closed-pack positions. When you lock out your elbow fully in extension with your forearm in supination—picture the top of a push-up or a bench press—this is its closed-pack position. It provides a sturdy feeling but can become vulnerable under heavy loads, especially if you repeatedly force a hyperextended lockout or if there’s poor control during explosive movements.
In contrast, the elbow’s open-pack position is found with approximately 70 degrees of flexion and slight supination. This angle feels comfortable for many bicep curl variations or elbow mobilizations. Athletes and active individuals often discover that being mindful of how they transition between moderate flexion and full extension can help preserve elbow health, particularly when increasing load or intensity in pressing movements.
Linking These Concepts to Injury Prevention and Performance
A fundamental advantage of understanding open-pack and closed-pack positions is that you can tailor your exercise technique to the demands of your specific goals. If you aim to maximize power output in a lift such as an overhead press or a squat, you might naturally move toward or briefly hold a joint in a closed-pack position. This can be safe and effective when paired with proper muscle activation, progressive load management, and attention to alignment. However, regularly over-stressing a locked joint—especially with abrupt impacts—can exacerbate wear and tear on the cartilage, ligaments, or tendons.
Meanwhile, if you are focusing on mobility, rehabilitation, or simply moving through a range of motion without heavy loading, an open-pack angle can be beneficial. Physical therapists use this principle in manual therapy sessions to gently mobilize the joint capsule and allow clients to gradually restore or enhance their movement. Athletes working to improve flexibility—such as increasing shoulder mobility for better overhead stability—often integrate exercises that specifically address open-pack ranges.
Gradual load progression is crucial when working out in and around both open and closed-pack positions. Jumping too quickly to heavy loads in closed-pack exercises can lead to injuries like shoulder impingement, hip strain, or elbow tendon issues, while neglecting stability in more open positions could also contribute to instability and compensations down the kinetic chain.
Examples for the Gym
Even without focusing on bullet points, it can help to imagine a few real-world training scenarios. If you find yourself struggling with overhead presses or experiencing discomfort at full extension, consider slightly modifying your overhead position. You might keep your shoulder from fully locking out or adopt a more neutral grip to avoid excessive external rotation. In squats or deadlifts, be mindful of how the hips shift from a more open angle at the bottom to near full extension at the top, and ensure you brace properly to prevent hyperextension. For the elbows, stay alert during the lockout phase of a press, controlling any “slamming” into extension and maintaining alignment in the wrists and shoulders to dissipate force across the entire arm and upper torso.
Final Takeaways
By recognizing when a joint is locked out and stable rather than loose and mobile, you’ll be able to fine-tune each repetition, reduce strain on vulnerable tissues, and build a stronger, healthier body overall. These principles apply to any athlete or gym enthusiast, not just professionals or those with prior injuries. For those who do have a history of joint pain, a thorough evaluation by a physiotherapist or sports medicine specialist can highlight the safest range of motion, identify key areas to strengthen, and suggest modifications that keep your training effective without exacerbating old issues.
Open-pack and closed-pack positions aren’t just academic terms reserved for textbooks. They’re extremely practical concepts that anyone hoping to lift heavy, move fluidly, and stay injury-free can apply to day-to-day workouts. Learning how your body responds and adapts to these joint angles will inform smarter exercise choices, keep chronic aches at bay, and ultimately enhance your performance in the gym and beyond.
References & Further Reading
American Physical Therapy Association (APTA): “Guide to Physical Therapist Practice”
Journal of Orthopaedic & Sports Physical Therapy
British Journal of Sports Medicine
International Journal of Sports Physical Therapy
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