Arm swing Arm Swing in Running: What Real Benefit?

Impact calculator: What gain for you?

For fun, here's a calculator to estimate the theoretical impact of arm swing on your performance.

Based on the above studies, this tool shows you how much time you would lose if you didn't swing your arms properly.

Obviously the result is far from reality because in practice nobody runs with arms so severely blocked. Unfortunately, I haven't found studies that measure the gain from small arm position modifications.

Why do we swing our arms when running?

When you run, your legs create a rotational moment around the vertical axis of your body. Without compensation, this movement would cause your torso to twist excessively with each stride, requiring significant muscular effort at the trunk level to maintain stability.

Opposite arm swing (right arm forward when left leg advances, and vice versa) naturally counterbalances this rotation. This biomechanical mechanism saves energy by limiting the work of trunk stabilizer muscles and reducing lateral body oscillations.

But what is the real impact of this swinging on your performance? This is what scientific studies have sought to measure very precisely.

How to Swing Your Arms for Maximum Performance?

Here are the key principles for efficient arm swing, based on biomechanical recommendations and observation of elite runners:

  • Elbow angle: Keep your elbows bent at approximately 90 degrees. A wider angle (straight arms) increases the moment of inertia and wastes energy.
  • Forward-backward motion: Swing your arms front to back, not side to side. Lateral movement creates parasitic torso rotations and slows you down.
  • Relaxed hands: Don't clench your fists! Keep your hands slightly open, as if holding a sheet of paper between your thumb and index finger. Tension travels up to the shoulders and increases energy expenditure.
  • Low and relaxed shoulders: Avoid raising or tensing your shoulders. They should remain stable and relaxed, allowing your arms to swing freely.
  • Pace-adapted amplitude: The faster you run, the more the swing amplitude naturally increases. At easy pace, the movement is moderate; when sprinting, arms rise higher in front (up to chin level) and further back.
  • Synchronization: Right arm moves forward with left leg, and vice versa. This opposing movement is instinctive, but some tired runners lose this coordination.

Practical tip: Film yourself from front and side for a few strides. Check that your arms don't cross your body's midline (sign of too much lateral movement) and that your shoulders remain stable without excessive rotation.

What scientific studies say

Several research projects have analyzed the impact of arm swing on running energy cost. The most comprehensive study is by Christopher Arellano and Rodger Kram from the University of Colorado, published in 2014.

Arellano & Kram (2014) Study Protocol

The researchers measured oxygen consumption (metabolic cost) of runners in different conditions:

  • Natural arm swing (reference)
  • Arms behind back (hands tied behind back)
  • Arms crossed on chest
  • Hands on head

Results: Energy overcost according to arm position

Study Tested condition Energy overcost
Arellano & Kram, 2014 Natural swing 0% (reference)
Arellano & Kram, 2014 Arms behind back ≈ +3%
Arellano & Kram, 2014 Arms crossed on chest ≈ +9%
Arellano & Kram, 2014 Hands on head ≈ +13%
Koo et al., 2025 Fixed vs actively swung arms ≈ +5%

Key conclusions

  • These studies cannot assess the impact of small defects in runners' arm positioning
  • Natural arm swing reduces running energy cost by 3 to 13% compared to blocked or constrained arms.
  • The greater the constraint on arms, the higher the energy overcost.
  • Arm swing also helps with lateral stability and reduces excessive torso rotations.
  • A 2011 study also shows that normal swinging minimizes energy cost and improves stride regularity.

Scientific references

  • Arellano, C. J., & Kram, R. (2014). The effects of step width and arm swing on energetic cost and lateral balance during running. Journal of Biomechanics, 47(13), 3515-3521.
  • Koo, T. K., et al. (2025). Musculoskeletal modeling of arm swing impact on running economy. Sports Biomechanics (modeling).
  • Collins, S. H., et al. (2009). A simple model of walking: metabolic cost and the preferred speed. Journal of the Royal Society Interface.

Interpretation and limitations

Important to understand

These figures compare extreme situations: nobody runs a marathon with arms crossed on chest or hands on head!

In reality, the goal is not to degrade your natural swing. Common mistakes that can cost a few percent of energy include:

  • Arms too stiff or tense
  • Swing that crosses excessively in front of body
  • Arms that rise too high (above shoulders)
  • Total absence of arm movement
  • Marked asymmetry between both arms

Optimal arm swing technique

Elbow angle

Maintain an angle of about 90° at the elbow, neither too tight nor too open.

Lateral amplitude

Hands should not cross the body's midline. Forward-backward movement, not lateral.

Natural opposition

Right arm forward when left leg advances, and vice versa. It's natural and automatic.

Relaxation

Shoulders low and relaxed. Hands slightly closed but without clenching fists.

Movement height

Hands oscillate between hip and chest approximately. No need to rise to shoulders.

Pace adaptation

The faster you run, the more ample and dynamic the swing. In slow jogging, it's more reduced.

Summary

  • Natural arm swing saves 3 to 13% energy compared to blocked arms according to scientific studies.
  • This saving translates into a potential improvement of a few percent of your race time if your technique is optimal.
  • The goal is not to "force" the swing, but to let the natural movement happen without constraint or rigidity.
  • Correct technique also helps prevent injuries by better distributing stress across the entire body.
  • ⚠️ Studies compare extreme situations. In practice, gains are infinitely more modest but undoubtedly real.

Arm technique is just one of many levers to improve your performance. Explore our other tools: