In a study published in Gait & Posture, Dr. Stephen Preece and his team decided to find out. They compared the forward lean of 14 elite runners vs. 14 hobby runners. He tested the runners at four different paces—from 8:07 to 4:47 per mile—and found that the elite group maintained a lean of about 3.5 degrees across all speeds, while the recreational runners increased their lean to eight degrees at the fastest pace.
He determined that a small lean, maybe three or four degrees is the best. Using more increases your usage of glutes and back muscles, which you don’t want.
In addition, an abstract presented by researchers at the American College of Sports Medicine in Boston said that postural lean can make you a more efficient runner. They used 16 runners capable of running a 22 minute 5K and had them run on a treadmill with a lean of 0 degrees, 4.18 degrees or 8.34 degrees. There was little difference between the first two conditions, but the 8.34-degree forward lean caused a four to six percent worsening of running efficiency.
The conclusion? Upright is best.
How to run upright:
Head: Keep your head held up and look at the horizon rather than looking at the ground. You see most runners only looking down. Keep your head up and this will help you stand up straighter.
If you feel yourself slouching, take a deep breath in and straighten your shoulders.
With your head up and looking ahead and your shoulders low and loose, your torso and back naturally straighten.
Keep them loose and close to your body. Keep your hands in an unclenched fist and fingers touching your palms.
Have someone videotape you, even with just a smartphone. You can analyze how far you bend and try to work at straightening. This will not only make you faster, but work your body less harder and give you better endurance.