An experimental study published in the Science Report found that shoes with the upward curve of toe springs on walking biomechanics in humans have less force on the foot muscles when walking compared to shoes with a flatter bottom.
The upturned toe of the shoe keeps the toes above the ground, maintaining a curved and upward posture, helping the forefoot roll forward when walking or running – this design is commonly used in most modern sports shoes. However, their effects on natural foot function and whether the feet are susceptible to damage have not been widely studied.
Freddy Sichting from the Technical University of Kainitz in Germany, Dan Lieberman from Harvard University in the United States, Nicholas Holowka from the State University of New York at Buffalo in the United States, and colleagues used a controlled experiment to study the effect of shoe toe curling on foot biomechanics. In the experiment, 13 participants first walked barefoot on the treadmill at a comfortable pace, and were then asked to wear specially designed four pairs of sandals to repeat this process. The toe area of these sandals would tilt up to varying degrees, simulating the curvature of modern sports shoes. The author reused trackers placed on each person’s knees, ankles, and feet to collect 3D motion data.

The author found that an upturned toe of the shoe can reduce the amount of work done by the muscles connecting the toes to the foot bone joints. The greater the upward tilt of the toes relative to other feet, the less work the foot muscles do to support the joints during walking.
The research results explain why shoes with upturned toe tips are so comfortable and popular, but also suggest that shoes with upturned toe tips may lead to weakened foot muscles under long-term wear. The author points out that this may lead to the susceptibility of shoe wearers to common pathological diseases, such as plantar fasciitis (inflammation of the area connecting the heel bone to the toe).
Summary:Although most features of modern footwear have been intensively studied, there has been almost no research on the effects of toe springs. This nearly ubiquitous upward curvature of the sole at the front of the shoe elevates the toe box dorsally above the ground and thereby holds the toes in a constantly dorsiflexed position. While it is generally recognized that toe springs facilitate the forefoot’s ability to roll forward at the end of stance, toe springs may also have some effect on natural foot function. This study investigated the effects of toe springs on foot biomechanics in a controlled experiment in which participants walked in specially-designed sandals with varying curvature in the toe region to simulate toe springs ranging from 10 to 40 degrees of curvature. Using inverse dynamics techniques, we found that toe springs alter the joint moments and work at the toes such that greater degrees of toe spring curvature resulted in lower work requirements during walking. Our results help explain why toe springs have been a pervasive feature in shoes for centuries but also suggest that toe springs may contribute to weakening of the foot muscles and possibly to increased susceptibility to common pathological conditions such as plantar fasciitis.