Effects of a leaf spring structured midsole on joint mechanics and lower limb muscle forces in running

Abstract

To enhance running performance in heel-toe running, a leaf spring structured midsole shoe (LEAF) has recently been introduced. The purpose of this study was to investigate the effect of a LEAF compared to a standard foam midsole shoe (FOAM) on joint mechanics and lower limb muscle forces in overground running. Nine male long-distance heel strike runners ran on an indoor track at 3.0 ± 0.2 m/s with LEAF and FOAM shoes. Running kinematics and kinetics were recorded during the stance phase. Absorbed and generated energy (negative and positive work) of the hip, knee and ankle joint as well as muscle forces of selected lower limb muscles were determined using a musculoskeletal model. A significant reduction in energy absorption at the hip joint as well as energy generation at the ankle joint was found for LEAF compared to FOAM. The mean lower limb muscle forces of the m. soleus, m. gastrocnemius lateralis and m. gastrocnemius medialis were significantly reduced for LEAF compared to FOAM. Furthermore, m. biceps femoris showed a trend of reduction in running with LEAF. The remaining lower limb muscles analyzed (m. gluteus maximus, m. rectus femoris, m. vastus medialis, m. vastus lateralis, m. tibialis anterior) did not reveal significant differences between the shoe conditions. The findings of this study indicate that LEAF positively influenced the energy balance in running by reducing lower limb muscle forces compared to FOAM. In this way, LEAF could contribute to an overall increased running performance in heel-toe running.

The Implications of Sports Biomechanics Studies on the Research and Development of Running Shoes: A Systematic Review

“…A total of two articles investigated the effect of midsole thickness designs on running performance/injury [ 8 , 12 ]. A total of three articles investigated the impact of midsole designs (materials and structures) on running performance/sports injury [ 22 , 23 , 24 ].…”

“…In the same year, the effect of a LEAF on joint mechanics and lower limb muscle forces during overground running was contrasted to a FOAM. Wunsch et al [ 23 ] stated that LEAF could improve running performance by substantially reducing energy absorption at the hip joint and energy production at the ankle joint.…”

“…In addition, in recent decades, BASF has jointly launched new midsole materials, E-TPU (foamed TPU) and Elastopan ® Sports Light, in cooperation with top international sports shoe manufacturers (e.g., Adidas (Herzogenaurach, Germany) and Brooks, (Seattle, WA, USA)), to improve the cushioning capacity and durability. Since there is a significant price difference in the midsole materials mentioned above, it is necessary to select appropriate midsole materials regarding the actual functionality of running shoes [ 23 , 24 ].…”

Acute Effects of Midsole Bending Stiffness on Lower Extremity Biomechanics during Layup Jumps

“…Contrary to this methodology, Smith [24] developed an elegant methodology that may be further representative in defining the MTP joint using two axes, which were constructed by connecting the first to the second MTP joint and connecting the second to the fifth MTP joint. In addition, the inconsistent observations across different studies [7,10,11,22,25] concerning the effect of stiff midsoles on the MTP joint might be caused by various factors, such as shoe materials and structures. Wunsch et al [25] compared the effect of a leaf spring structured midsole shoe (LEAF) and a stand-foam midsole shoe (FOAM) on the joint mechanics of the lower extremities; they indicated that LEAF is more effective in improving running performance.…”

“…In addition, the inconsistent observations across different studies [7,10,11,22,25] concerning the effect of stiff midsoles on the MTP joint might be caused by various factors, such as shoe materials and structures. Wunsch et al [25] compared the effect of a leaf spring structured midsole shoe (LEAF) and a stand-foam midsole shoe (FOAM) on the joint mechanics of the lower extremities; they indicated that LEAF is more effective in improving running performance. Therefore, additional studies are required to determine the effect of stiff midsoles on the biomechanics of the MTP joint, and an increasingly optimized strategy for modulating midsole stiffness should be explored.…”