Fine-tuning the Sacroiliac Joint for Sport Performance

The sacroiliac joints (SIJs) are specialised structures that serve as stable yet slightly flexible connections between the lower limbs and the rest of the body, allowing efficient force transmission. These joints are large, flat, and combine both synovial and fibrous elements. Their highly congruent surfaces offer considerable friction, and strong ligaments further support their function, resulting in effective force transfer with minimal movement (Vleeming et al., 2012).

Research varies on the extent of normal SIJ movement: some sources report up to 8 mm of translation (Goode et al., 2008), while others suggest figures as low as 1.4 to 3.1 mm (Garras, Carothers and Olson, 2008). Nonetheless, it is consistently noted that movement at the SIJ is quite limited.

SIJ kinematics during motion are complex due to the interplay of forces from the spine, upper limbs, and lower limbs. Rotational movement at the pubic symphysis is crucial for the pelvis to function as a unified structure, enabling opposing movements of the SIJ during walking. When the lumbar spine flexes, the sacrum tilts forward, causing external rotation and outflaring—this process is termed 'nutation'. Conversely, lumbar extension leads to an opposite reaction known as 'counter-nutation' (Lavignolle et al., 1983).

The muscles of the trunk also play a vital role in managing SIJ stability and movement. Groups such as the abdominals, gluteals, hamstrings, latissimus dorsi, spinal extensors, and the thoracolumbar fascia work together in cross-patterned slings, helping to lock the SIJ during activity. The effect these muscles have on joint stability is often called force closure (Vleeming et al., 1997).

The interosseous region of the sacroiliac joint is crucial for stability because it contains the robust interosseous ligament. This ligament has both deep and superficial parts, bridging the space between the posterior sacrum and ilium with short, dense, and exceptionally strong multidirectional fibers.

Its stabilizing function was highlighted in a cadaver study by Miller and colleagues (1987). In this study, the pubic symphysis was removed and all the supporting muscles and ligaments were severed before researchers tried to move the sacrum relative to the ilium—though the interosseous ligament remained untouched. Remarkably, even with other supports eliminated and the pelvic ring disrupted, sacroiliac movement hardly changed. These findings clearly show that the interosseous region of the sacroiliac joint is essential for maintaining stability of the pelvic ring, especially during upright positions.

Besides the interosseous ligament providing strong support, the sacroiliac joint's movement is also regulated by various capsular and extracapsular soft tissues. On the front side, the joint is covered by the anterior sacroiliac ligament, which is an extension of the capsule; this ligament is thin, relatively weak, and doesn't significantly restrict movement. In contrast, the back of the joint is protected by the superficial part of the interosseous ligament, attaching at S1 and S2 of the sacral crest, and the long dorsal sacroiliac ligament. The latter originates from the lateral sacral crest at S3 and S4 and extends upward and outward to attach to both the inner iliac crest and the PSIS. Fascia from the gluteus maximus muscle strengthens the ligament just beneath the PSIS. Additionally, the long dorsal sacroiliac ligament is reinforced by fibers from the thoracolumbar fascia, erector spinae, and multifidus muscles. These robust connections help stabilize the sacrum by limiting counternutation, effectively locking the joint and protecting it from excessive motion.

Sacrum Self-Locking's Mechanism

The stability of the SI joint is central to locomotion and we have previously mentioned the force closure mechanism as described by Vleeming et al. (1997).

Snijders et al. (1993) called this mechanism form and force closure system, referring to the coupled action of the restraining sacroiliac ligaments and muscles providing the force closure with the keystone-shaped sacrum providing the form closure (Michaud, 2011).

Form and force closure of the SI joint (from Vleeming et al., 1997)

The integration of form and force closure systems results in a self-locking mechanism that ensures substantial stability against vertical loads while reducing the need for muscular exertion. The effectiveness of the sacrum's self-locking mechanism has been demonstrated by Gunterberg, Romanus and Stener (1976), who observed that a vertically loaded cadaveric spine was able to withstand a downward shear force of 4,800 N without incurring damage. The capacity to endure such considerable axial forces has been pivotal in the evolution of human bipedality (Michaud, 2011).

Sacroiliac Joint Dysfunction and Gait Pattern

How does sacroiliac joint dysfunction manifests itself from a movement pattern point of view? Athletes presenting with an asymmetrical gait pattern often refers to have low back and hip disorders, such as sacroiliac joint dysfunction. Feeney et al. (2018) found a link between SI joint dysfunctions and reduced coactivation of the gluteus maximus and contralateral latissimus dorsi, which both works together to provide joint stability during walking and running.

A sign of suboptimal function of sacroiliac joint in running-based activities could be highlighted by an asymmetrical hip extension pattern potentially leading to a decrease in vertical force production during the maximum speed phase.

In their 2018 EMG study, Feeney and colleagues found that subjects with sacroiliac joint dysfunction exhibited reduced hip extension and lower peak vertical ground reaction forces on the affected side compared to the unaffected side.

It seems that the synergistic action of the gluteus maximus and contralateral latissimus dorsi plays an essential role in providing the necessary force transmission for proper SI joint stability to sustain locomotion.

A study from Caldeira et al. (2024) demonstrates that myofascial force transmission between the latissimus dorsi and contralateral gluteus maximus is functionally relevant in running-based activities, mediated through the thoracolumbar fascia. This connection influences hip mechanics and may contribute to performance and injury risk.

How to Maintain Proper Sacroiliac Joint Function for High-Intensity Running

Implementing regular therapeutic inputs through proper targeting of the myofascial structures linking upper and lower body can help in maintaining an optimal tension on the thoracolumbar fascia, creating a stable belt for power and force transmission.

Exercises targeting diagonal patterns may further provide with the necessary stimulus for synergistic and coordinated action of gluteus maximus and contralateral latissimus dorsi.

The sacroiliac joint may move only a few millimeters, yet its stability is fundamental for powerful and efficient athletic performance. When the SIJ functions optimally, force is transferred seamlessly between the upper and lower body, allowing athletes to run, jump, and change direction with confidence. Dysfunction, however, can quickly disrupt gait mechanics and reduce force output. For coaches and athletes, the takeaway is clear: targeted training of the gluteal–latissimus sling and myofascial connections is not just rehabilitation—it’s performance insurance. Protecting SIJ integrity means unlocking resilience, speed, and longevity in sport.

Antonio Robustelli is the mastermind behind Omniathlete. He is an international high performance consultant and sought-after speaker in the area of Sport Science and Sports Medicine, working all over the world with individual athletes (including participation in the last 5 Olympics) as well as professional teams in soccer, basketball, rugby, baseball since 23 years. Currently serving as Faculty Member and Programme Leader at the National Institute of Sports in India (SAI-NSNIS).