Research Question “Biomechanical advantages of barefoot running over shod running in athletes. ” Introduction Running is a popular activity around the globe. Recreational runners have been shown to be susceptible to injuries; epidemiological studies have shown that 35-56% of all runners develop overuse injuries during one-year period (Braunstein et al. , 2010). Knee and the ankle joints are most commonly injured and are linked with one-fifth of running-related injuries (Sinclair, 2014). One of the main reasons behind these injuries is the complex structure of the foot.
The human foot involves 26 bones, 33 joints and 19 muscles. The bones are arranged in a way that forms medial longitudinal arch, which makes it ideal for its function of supporting the weight of the body and spreading the forces during the gait. Besides the structure of the bones there is a complex arrangement of both intrinsic and extrinsic muscles, which connects with the somesthetic system of the body to control balance and movement.
There is a vicinity of 104 cutaneous mechanoreceptors situated in the foot sole (Franklin et al. 2015). Recently, unshod (barefoot) running has been the center of consideration in footwear for runners and has gained favor in bio-mechanical research as an alternative to highly marketed running sneakers. Various barefoot inspired models are commercially accessible, and available in many styles from moderate e. g. Inov-8 Evoskin and Vibram Five Fingers to more organized styles which offer some mid-sole interface e. g. Nike Free (Sinclair, 2014). Many researchers are touting the advantages to barefoot running over more common methods.
Lieberman et al. reports a decreased occurrence of chronic running injuries associated with unshod motion (Lieberman et al. , 2010). The same group found that habitual unshod runners and habitual shod runners have distinctive foot strike patterns (Lieberman et al. , 2010). Rao also observed various kinematic differences were observed when habitual shod runners were made to run barefoot (Rao et al. , 2015). Moreover, literature supports that unshod running improves performance and reduces risk of injury (Thompson et al. 2015), and others found that barefoot running results in gait alterations that may lead to some proposed advantages (Rao et al. , 2015). It has been consistently observed that the stride length and the contact time is reduced while stride frequency increases in barefoot running as compared to classical shod running (Rao et al. , 2015).
Gait changes also include switching from a rear foot strike (RFS) pattern to a mid/forefoot strike (M/FFS) pattern (Thompson et al. , 2015). However, 72-89% individuals are RFS runners, while the remaining are M/FFS runners who wear cushioned shoes (Thompson et al. 2015). Ultimately a plantarflexed foot will lead to less collision forces while landing and will provide more ankle compliance as stated by Lieberman. Thus, the purpose of this study is to examine differences and evaluate the possible biomechanical advantages of the barefoot running in habitually shod runners. Methodology Participants: Twenty healthy, injury-free athletic male runners engaged in running activities minimum 3 times per week and were right foot dominant. Runners habitually used shod equipment and were be naive to unshod running.
Participants were recruited from the track and field teams of various universities in New York City and they were free from any pathology during the time of data collection. 20 subjects participated (age: 24 + 1. 8 years; height: 176 + 4. 6 cm; weight: 167 + 7. 8 lbs. ; BMI: 23. 32 + 1. 08 kg/ m2). All running tests and experiments were conducted at the Sports Biomechanics Laboratory. All runners completed an informed consent prior to the study and volunteer to participate in the study. Runners with any kind of foot deformities and foot surgery in past year were excluded.
Few of the athletes denied participating in the study due to various reasons. Procedure: Participants were asked to perform the tests on their regular training day. No change was made in their regular daily routines. Before starting the test, all the runners were asked to perform the specified stretching session as a warm up. Runners were instructed to perform five running trials over a 30 m walkway at 4. 0 m/s in the biomechanical laboratory with shoes on. The participants struck an embedded piezoelectric force platform sampling at 1000 Hz with their right foot (Sinclair, 2014).
Running velocity was also monitored using infra-red timing gates. A motion capture system was also used to collect 3D kinematics. Then the synchronized kinematic and ground reaction force data were obtained using Qualisys Track Manager Software. The calibrated anatomical system technique was utilized to quantify joint kinematics. To define the anatomical frames of the right foot, shin and thigh, retro reflective markers were positioned onto calcaneus, 1st and 5th metatarsal heads, medial and lateral malleoli, medial and lateral epicondyle of the femur and greater trochanter.
Using the same settings the participants were asked to perform the same test without wearing footwear. Separate static trials were obtained for both the conditions. The readings were noted and comparison of the forces was done. Data processing and analysis: GRF and 3D kinematic data were filtered separately and analyzed using Visual 3D. 3D kinematics of the knee and ankle were calculated using XYZ Cardan sequence of rotations. Joint kinetics was computed using Newton-Euler inverse-dynamics. Previously utilized algorithmic models were used to determine various forces.
Differences in knee and ankle loading parameters across the footwear conditions were examined using one-way repeated measures ANOVA. Results Table 1 represents discrete kinematic parameters for the knee and ankle joint. The results indicate that conventional footwear significantly influenced both knee and ankle kinetic parameters. Knee Load: A significant main effect was found for Knee Extensor Movement (ME). Here ME was significantly greater in the conventional footwear as compared to barefoot.
A significant main effect was also observed for Patello Femoral Contact Force (PTF) which was also significantly greater in conventional footwear. A further main effect was found for Pressure (PP) which was significantly lesser in barefoot running. Ankle Load: A significant main effect was found for Peak Patellar Extensor Movement (MPF) which was significantly greater as compared to conventional footwear. A significant main effect was also found for Achilles Tendon Force (ATF) which showed a greater value in barefoot as compared to conventional footwear.
