Baseball pitching is a complex movement that relies on coordination across multiple joints and planes of motion. Among these, the ankle is often overlooked, even though it is the first link in the kinetic chain to touch the ground. If the ankle isn’t functioning properly, the foundation of the delivery is compromised, which can limit pitching velocity, reduce efficiency, and increase injury risk. This article explores the triplanar rotation of the ankle (sagittal, frontal, and transverse) and its role in pitching mechanics (especially stride length), performance, and injury prevention.

Understanding Triplanar Ankle Rotation In Pitching Mechanics

The ankle operates in three planes at once:

Sagittal (up and down): dorsiflexion (toes up) and plantarflexion (toes down) load the ankle like a spring and drive the body forward.
Frontal (side to side): inversion (inside edge down) stabilizes the drive foot, while eversion (outside edge down) helps absorb and transfer force after landing.
Transverse (rotation): tibial rotation twists the ankle against the ground, producing torque (the free moment) that blends linear drive into rotational power.

In pitching, both the drive leg ankle and the landing leg ankle work triplanar moving in the sagittal, frontal, and transverse planes to create, stabilize, and transfer force. The drive ankle begins in dorsiflexion and inversion as the pitcher rides down the mound, storing energy and creating a strong base. As the tibia rotates inward, the ankle rotates outward (external rotation), producing torque against the ground. It then transitions into plantarflexion and eversion (toes down, outside edge down), releasing stored force forward and blending linear drive into rotational power. Meanwhile, the landing ankle must absorb and redirect that force: it typically lands in slight dorsiflexion and quickly moves into eversion and internal rotation, acting like a shock absorber that braces the front side and channels ground reaction forces through the trunk and arm. Together, the coordinated triplanar actions of both ankles ensure efficient propulsion, stability, and energy transfer up the kinetic chain.

Sagittal Plane Dynamics

Dorsiflexion and plantarflexion generate the ground reaction forces (GRF) that propel the pitcher forward. Proper dorsiflexion allows smooth weight transfer and momentum buildup, while limitations disrupt balance and forward drive, forcing the arm to absorb more stress.

"ankle mobility constraints (specifically dorsiflexion range of motion) disrupt center of gravity progression (dynamic balance) and forward momentum generation during the delivery that transfer to the upper extremity, thus predisposing the shoulder and elbow to injury" [1]

Frontal Plane Dynamics

Inversion and eversion are key for stability and force transfer. The drive ankle typically loads into inversion as the pitcher rides down the mound, then transitions into eversion and plantarflexion to amplify propulsion. With longer strides, this transition happens earlier; with shorter strides, it occurs later, sometimes after foot strike.

The stride ankle usually shows greater eversion after landing, which braces the front side, absorbs force, and redirects energy into the trunk and arm. Without this balance, pitchers risk energy leaks and reduced velocity.

"Early in the generation phase, drive-ankle inversion was notably higher with the longer strides, whereas inversion was more pronounced and occurred later in the pitching cycle after foot contact when using the shorter strides. When inverted, the drive ankle with longer strides depicted a greater maximal eversion moment (approximately 35% BW•H). The greater eversion moments observed during single support are likely attributable to greater propulsive, anteriorly directed ground reaction force and impulse when pitching with longer strides. Compared with shorter strides during propulsive generation, longer stride pitching infers the importance of the force couple between drive-ankle plantar flexion and eversion moments to develop peak anterior ground reaction forces in propulsion before foot contact and appears to coordinate instants single support ankle co-contraction that may precipitate improved energy storage for the knee and hip" [1]

Transverse Plane Dynamics

Tibial rotation drives ankle rotation in the transverse plane. Internal tibial rotation increases external ankle rotation, creating torque through the free moment that helps generate propulsion. The drive ankle contributes most before foot strike, especially with longer strides, while the stride ankle provides internal rotation during braking to stabilize and transfer energy.

“In closed kinetic chain lower-extremity movement, internal–external ankle rotation is described by transverse tibial rotations relative to either the planted drive or stride foot. Internal tibial rotation about the planted foot increases external ankle rotation, whereas tibial external rotation denotes internal ankle rotation. The greater contribution of external ankle rotation and respective angular velocities, depicted as greater internal tibial rotation during the generation phase, is thought to augment propulsive effort through the ground reaction free moment. Depending on the direction of the free moment, it acts to resist the tendency of the foot to either abduct (toe out) or adduct (toe in) with respect to the ground. One possible advantage is enhanced fictional force by increasing the ability to apply free moments, which occurs early in the pitching cycle before stride-foot contact. With shortened generation times owing to the shorter stride, the lower external foot rotation moments during propulsion combined with minimal external ankle rotation throughout the pitching delivery may further the need to coordinate drive-ankle propulsive effort following stride-foot contact during double support.” [1]

Triplanar Coordination and Stride Length

Stride length shifts the timing and magnitude of ankle contribution. Longer strides load dorsiflexion and inversion earlier, then transition into plantarflexion and eversion before foot strike, producing strong GRFs and efficient energy transfer. Shorter strides delay this transition, prolonging propulsion after landing and relying more on the trunk to maintain velocity, especially under fatigue.

"longer strides depicted more advantageous triplanar mechanics in propulsion, whereas shorter strides prolonged propulsion and executed higher bracing dynamics later in the delivery, perhaps to amplify transverse trunk momentum to maintain ball velocity" [1]

Practical Implications

Optimizing triplanar ankle function enhances velocity, stability, and energy transfer while reducing stress on the arm.

Ankle mobility & strength

Banded inversion/eversion
Calf raises and isometric holds
Tibialis raises
Plyometric hops, bounds, jumps
Single-leg strength (pistol squats, lunges, rotational variations)

"To protect players from injury and improve performance, baseball-specific programs designed by a multidisciplinary team comprised of physicians, athletic trainers, physical therapists, strength coaches, and sport scientists should include routine ankle mobility and strength evaluations that is believed to be necessary for maintaining proper ground reaction force profiles. Finally, biomechanical assessments should support preventative efforts by the multidisciplinary team in optimizing strength length and functional ankle mechanics for baseball pitchers" [1]

Biomechanics Stride length optimization
3D motion capture and biomechanics data allow coaches to tailor stride length to individual mechanics, ensuring efficient ankle function and force transfer.

“This work strongly recommends high-performance teams in baseball to assess stride length critically through 3D optical tracking methods, as compensatory mechanics or ineffective coaching suggestions can be avoided by including ankle motion analysis in their interpretation of efficient throwing mechanics.." [1]

Footwear & surface
Cleats on dirt provide better friction and stability than turf, where front foot sliding at contact often leaks energy and reduces velocity.

Conclusion

The triplanar rotation of the ankle integrates sagittal, frontal, and transverse motions to generate force, stabilize balance, and transfer energy through the kinetic chain. Optimizing these mechanics, especially in relation to stride length, supports velocity, efficiency, and injury prevention in pitchers. While this cited research highlights the ankle’s critical role in both the drive and landing legs during pitching, more work still needs to be done to fully understand how ankle function influences velocity, command, and injury risk. Because the ankle is also central to sprinting, jumping, and overall athleticism, it deserves the same level of attention as the hips, trunk, and lead leg block in pitching mechanics. Coaches who value identifying weak links in the kinetic chain must learn how to assess and address deficiencies in ankle mobility, strength, and control. Doing so will not only improve energy transfer and performance but also serve as a key step in preventing injuries across all levels of baseball.

References

Crotin, R.L.; Ramsey, D.K. An Exploratory Investigation Evaluating the Impact of Fatigue-Induced Stride Length Compensations on Ankle Biomechanics among Skilled Baseball Pitchers. Life 2023, 13, 986. https://doi.org/10.3390/life13040986

From the Ground Up: Triplanar Ankle Mechanics and Its Role in Pitching Velocity