Pursuing symmetry has been a cornerstone of sports science, particularly in sprinting, where even small biomechanical inefficiencies are thought to impact performance.

The traditional belief is that asymmetries—differences in strength, coordination, or mechanics between limbs—lead to inefficiencies, increased injury risk, and slower sprint times.

Many coaches and practitioners aim to correct these imbalances, assuming that a more symmetrical running gait will enhance performance.

However, emerging research suggests that asymmetry is a natural and often functional characteristic of human movement, with many elite sprinters exhibiting noticeable imbalances without adverse effects.

Does sprinting asymmetry hinder performance, or can it be a natural and even beneficial characteristic of elite sprinters?

Study: Asymmetry in sprinting: The myth of perfection and the reality of performance

What did the researchers do?

• The commentary reviews biomechanical studies on asymmetry in sprinting, analyzing data from world-class sprinters.
• It specifically references the 2017 IAAF 100m Finals, where researchers used 3D motion analysis to measure asymmetry across different phases of sprinting.
• Usain Bolt's unique biomechanics, including his natural asymmetries, are used as a case study to explore whether such imbalances are detrimental or beneficial.

What were the results?

Dispelling the Myth

• Low-to-moderate asymmetry is common in world-class sprinters → Research on elite athletes found that asymmetry does not significantly impact overall sprint performance.
• Performance is not necessarily tied to perfect balance → Studies indicate that correcting minor asymmetries may disrupt natural biomechanics rather than enhance performance.
• Asymmetry may be phase-specific → Sprinting phases (acceleration, max velocity, deceleration) show asymmetrical patterns that don’t necessarily correlate with lower performance.

Usain Bolt

• Usain Bolt is an example of a successful (read: fastest man alive) asymmetrical sprinter.
• His right leg strikes the ground with 13% more force.
• His left leg stays on the ground 14% longer due to scoliosis and leg length differences.

Modifiable vs Non-Modifiable

This figure is a good reminder that not all factors are modifiable and may contribute to asymmetries. Functional asymmetries likely sit between dysfunctional asymmetry and perfect symmetry.

What does this mean?

• Perfect symmetry is not a requirement for elite sprinting → Many of the fastest sprinters in the world exhibit natural asymmetries without negative performance consequences.
• Coaches should focus on function rather than symmetry → Rather than forcing perfect balance, it is more important to address performance-limiting deficits.
• Individualized training is key → Some asymmetries may be biomechanically advantageous for specific athletes, so training should be tailored accordingly.

Limitations

• Most studies examined elite or world-class sprinters, leaving questions about how asymmetry affects non-elite populations.
• While asymmetry may not affect performance, its impact on injury risk is still not fully understood.

Coach's Takeaway

• If an athlete performs well and remains injury-free, forcing symmetry may do more harm than good.
• Focus on how asymmetry impacts mechanics and performance rather than chasing arbitrary balance benchmarks.
• Track inter-limb differences over time, ensuring improvements are from strengthening weaker areas rather than weakening dominant limbs.