Dynamic loading and kinematics analysis of vertical jump based on different forefoot morphology

Shu et al. SpringerPlus (2016) 5:1999 DOI 10.1186/s40064-016-3682-3 Open Access RESEARCH Dynamic loading and kinematics analysis of vertical jump based on different forefoot morphology Yang Shu1, Yan Zhang2,3,4, Lin Fu1, Gusztáv Fekete3, Julien S. Baker5, Jianshe Li2 and Yaodong Gu1,2* *Correspondence: 1 Faculty of Sports Science, Ningbo University, No. 818, Fenghua Road, Jiangbei District, Ningbo, Zhejiang Province, China Full list of author information is available at the end of the article Abstract Purpose: This study examined differences in ankle motion and plantar pressure between habitually barefoot male (HBM) and habitually shod male (HSM) during vertical jump. Methods: Eighteen habitually barefoot males and twenty habitually shod males volunteered to join the test. Distance between hallux and second toe was measured with Easy-Foot-Scan. Plantar pressure and ankle kinematics were measured with EMED force platform and Vicon motion analysis system respectively. T test was taken to analyse the significant differences using Stata 12.0 software. Results: The distance between hallux and other toes in HBM was greater than it in HSM. HBM showed larger plantar loading under hallux and medial forefoot, while HSM showed lager plantar loading under medial and central forefoot. HBM had smaller ankle plantarflexion, eversion and external rotation than HSM. Conclusion: Findings of this study provide basic information for further studies on different hallux/toe function in motion control between habitually shod and barefoot populations. Keywords: Foot morphology, Toes, Vertical jump, Plantar pressure Background Human is bipedal species using two feet to stand and move. Franklin et al. (2015) considered that human feet took the effort of balance and movement control. Morphological differences in foot could cause many foot malfunctions, disorders and deformity (Ledoux et al. 2003). Furthermore, foot morphology had a close relationship with areas: forefoot and toes have been reported to be the prominent target areas (Lambrinudi 1932; Rolian et al. 2009; Hoffmann 1905; D’AoÛt et al. 2009). Wolf et al. (2008) found that acquired behaviour such as footwear wearing may lead to foot structure deformation, such as flatfoot and hallux valgus. Toe separation of habitually barefoot populations showed to be more obvious compared with habitually shod populations (Wolf et al. 2008). In addition, previous studies indicated that habitually barefoot individuals were less likely to be injured than habitually shod ones during running (Robbins and Hanna 1987; Robbins et al. 1988). Lieberman et al. (2010) ascribed this difference to different © The Author(s) 2016. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Shu et al. SpringerPlus (2016) 5:1999 Page 2 of 9 foot strike patterns. Clinical research presented that metatarsal pathologies were more critical in habitually shod populations than in habitually barefoot populations (Zipfel and Berger 2007). Jumping as a fundamental motion in sports frequently leads to lower limb injuries, primarily due to the rapid shock to lower limbs at landing (Vint and Hinrichs 1996; Doherty et al. 2014). Ankle sprain has been considered as one of the most common injuries in various sports with frequent jump motion such as volleyball, basketball and soccer. According to the survey, there are approximately 5600 incidences of ankle sprain per day in the UK, a mere between 3 and 5% of all Emergency Department visits (Pijnenburg et al. 2000). Larger plantar loading at forefoot and toes areas in take-off and landing may increase the risk of metatarsal injuries. However, whether there are differences in ankle motion and plantar loading between habitually barefoot populations and habitually shod populations in jumping remained to be unclear. Therefore, the purpose of the study was to investigate difference in ankle kinematics and plantar pressure under forefoot and toes regions between habitually shod male (HSM) and barefoot male (HBM) during vertical jump based on different forefoot morphology. It was hypothesised that HBM and HSM would present different ankle motions (ankle variation angles and maximal or minimal angles) and plantar pressure characteristics related to different hallux and second toe separation. Methods Participants Eighteen habitually barefoot males and twenty habitually shod males volunteered to join the test. All participants are Ningbo University students. The HBM come from South India, who are accustomed to walking and exercising barefoot or with slippers/flip-flops since born in daily life. The HSM are accustomed to wearing different kind of shoes since born in daily life. Basic information of participants is listed in Table 1. The Ethics Committee of Ningbo University approved this study (No. 2016FS021) and participants were informed of experiment procedures and requirements with obtained consent. They were free from injury or surgery of their lower extremity in the past six months. Easy-Foot-Scan (EFS), OrthoBaltic (Kaunas, Lithuania) was used to measure forefoot morphological difference of the minimal distance between hallux and the second toes. The minimal distance of HSM was smaller than the distance of HBM (Fig. 1a, b; HSM: Table 1 Descriptive statistics for age, height, mass, and foot length Habitually barefoot males (N = 18) Mean (SD) Age (years) Height (cm) Mass (kg) BMI (kg/m2) Right leg length (cm)a Right feet length (cm) 24 ± 1.2 Habitually shod males (N = 20) Mean (SD) 24 ± 2.1 165.3 ± 1.2 172.1 ± 1.6 23.88 ± 0.93 22.31 ± 1.97 25.5 ± 1.4 25.5 ± 0.9 65.4 ± 6.9 86.5 ± 2.8 66.2 ± 6.5 89.3 ± 3.9 SD standard deviation a Right leg length measurement from right anterior superior iliac spine to medial malleolus Shu et al. SpringerPlus (2016) 5:1999 Fig. 1 Foot of habitual shod subject (a), foot of habitual barefoot subject (b) and anatomical parts of plantar pressure (c) 6.28 ± 1.42 mm, HBM: 23.75 ± 2.09 mm, P < 0.001 through the independent-samples T test). Experiment procedure An 8-camera Vicon motion analysis system (Oxford Metrics Ltd., Oxford, UK) was used to collect three-dimensional kinematic data at a frequency of 200 Hz. Participants were required to wear tight shorts. 16 reflective points (diameter 14 mm) were attached on different key locations of right and left lower extremity respectively including anterior– superior iliac spine, posterior–superior iliac spine, lateral mid-thigh, lateral knee, lateral mid-shank, lateral malleolus, second metatarsal head and calcaneus (Fig. 2). Kinetic data were recorded at 50 Hz using an EMED pressure plate (Novel, Germany). All pa (...truncated)