Comparison of Plantar Pressure Distribution between Different Speed and Incline During Treadmill Jogging

The aim of this study was to examine the effect of changes in speed and incline slope on plantar pressure distribution of the foot during treadmill jogging. Plantar pressure parameters were measured with the Pedar-X system in twenty healthy girls (mean age of 20.7 years, mean height of 1.60m, and a mean weight of 53.35kg). Because variations in walking speed or slope can significantly change the magnitude of plantar pressure, comparisons of plantar pressure distribution between the two independent protocols during treadmill jogging were considered in this study. First, the subjects ran at the same speed of 2 m·s^-1 with different incline slopes of 0%, 5%, 10%, and 15%. Second, they ran on the same slope of 0% with different speeds of 1.5 m·s^-1, 2.0 m·s^-1, and 2.5 m·s^-1. The peak pressure of the eight plantar surface areas, apart from the medial forefoot and the hallux, significantly increased (p < 0.05) with an increase of 33% of peak pressure from 1.5 m·s^-1 to 2.5 m·s^-1 (speed) at heel region. In contrast, the peak pressures at the heel, medial fore-foot, toe and hallux decreased significantly (p < 0. 05) with increasing incline slope. At the heel, peak pressure reduced by 27% from 0% to 15% incline, however, pressure at the lateral midfoot region increased as following. Different speeds and incline slopes during jogging were associated with changes in plantar pressures. By systematic investigation of foot kinematics and plantar pressure during jogging with varying incline slope and speed, the results of this study provided further insight into foot biomechanics during jogging.

Key points

• The study aimed to compare the plantar pressure distribution of the foot between different incline and speed during treadmill jogging by using plantar insole measurement system.
• With the increase of speed, apart from the hallux and medical forefoot, the peak pressure of all regions was raised significantly.
• As the slope increased, there was reduced peak pressure of the heel, medial forefoot, and hallux and toes.

Key words: Jogging, plantar pressure, incline, speed     

Short-Term Free-Fall Landing Causes Reduced Bone Size and Bending Energy in Femora of Growing Rats

The purpose of this study was to determine the effects of a mechanical loading course (short-term free-fall landing) on femoral geometry and biomechanical properties in growing rats. Thirty-two female Wistar rats (7-week-old) were randomly assigned to three groups: L30 (n = 11), L10 (n = 11) and CON (n = 10) groups. Animals in the L10 and L30 groups were subjected to a 5-day free-fall landing program in which animals were dropped from a height of 40cm 10 and 30 times per day, respectively. Landing ground reaction force (GRF) was measured on the 1^st and 5^th days of landing training. All animals were subjected to two fluorescent labeling injections on the days before and after the 5-day landing training. Three days after the last labeling injection, animals were sacrificed under deep anesthesia. Methods of dynamic histomorphometry, tissue geometry and tissue biomechanical measurements were used to investigate the response in femora. A significant decrease in peak GRF in the hind-limb was shown from day 1 to day 5. No significant difference was shown among groups in dynamic histomorphometry. Biomechanical property analyses showed significantly lower maximal energy and post-yield energy in the L10 and L30 groups as compared to the CON group (p < 0.05). Moreover, geometric measurements revealed that cross-sectional cortical areas and thicknesses were significantly lower in landing groups than in the CON group. Short-term (5-day) free-fall landing training resulted in minor compromised long bone tissue, as shown by reduced bending energy and cortical bone area but not in other mechanical properties or tissue measurements (e.g. weights and length) of growing female rats. Further studies would be valuable to investigate whether this compromised bone material represents the existence of a latency period in the adaptation of bone material to external mechanical loading.

Key points

• Short-term free-fall landing causes compromised bone material as shown by reduced post-yield energy in long bones of rodents.
• The results of the current study suggest the existence of unsettled bone material after a short-term mechanical loading regime.
• The connection of the present animal study to the stress fractures occurring in young athletes needs to be clarified.

Key words: Bone, mechanical load, biomechanical properties, post-yield energy, animal model     

Landing Techniques in Beach Volleyball

The aims of the present study were to establish a detailed and representative record of landing techniques (two-, left-, and right-footed landings) in professional beach volleyball and compare the data with those of indoor volleyball. Beach volleyball data was retrieved from videos taken at FIVB World Tour tournaments. Landing techniques were compared in the different beach and indoor volleyball skills serve, set, attack, and block with regard to sex, playing technique, and court position. Significant differences were observed between men and women in landings following block actions (χ²(2) = 18.19, p < 0.01) but not following serve, set, and attack actions. Following blocking, men landed more often on one foot than women. Further differences in landings following serve and attack with regard to playing technique and position were mainly observed in men. The comparison with landing techniques in indoor volleyball revealed overall differences both in men (χ²(2) = 161.4, p < 0.01) and women (χ²(2) = 84.91, p < 0.01). Beach volleyball players land more often on both feet than indoor volleyball players. Besides the softer surface in beach volleyball, and therefore resulting lower loads, these results might be another reason for fewer injuries and overuse conditions compared to indoor volleyball.

Key Points

• About 1/3 of all jumping actions in beach volleyball result in a landing on one foot.
• Especially following block situations men land on one foot more often than women.
• Landing techniques are related to different techniques and positions.
• Landings on one foot are less common in beach volleyball than indoor volleyball. This could be a reason for fewer injuries and overuse conditions.

Key words: Video analysis, gender differences, volleyball, injuries, overuse condition     

Effects of wearing foot orthosis with medial arch support on the fifth metatarsal loading and ankle inversion angle in selected basketball tasks

STUDY DESIGN: Preintervention and post-intervention, repeated-measures experimental design. OBJECTIVES: The objective was to investigate the effects of foot orthoses with medial arch support on ankle inversion angle and plantar forces and pressures on the fifth metatarsal during landing for a basketball lay-up and during the stance phase of a shuttle run. BACKGROUND: Proximal fractures of the fifth metatarsal, specifically the Jones fracture, are common in sports. Wearing foot orthoses with medial arch support could increase the ankle inversion angle and the plantar forces and pressure on the fifth metatarsal that may increase the risk for fifth metatarsal fracture, METHODS AND MEASURES: Three-dimensional (3-D) videographic, force plate, and in-shoe plantar force and pressure data were collected during landing after a basketball lay-up and during the stance phase of a shuttle run with and without foot orthoses with medial arch support for 14 male subjects. Two-way ANOVAs with repeated measures were performed to compare ankle inversion angle, maximum forces, and pressure on the fifth metatarsal head and base between conditions and between tasks. RESULTS: The maximum ankle inversion angle and maximum plantar force and pressure on the base of the fifth metatarsal during both tasks as well as the maximum plantar force and pressure on the head of the fifth metatarsal during the stance of the shuttle run were significantly increased (P< or =026) when wearing foot orthoses. No significant differences were found in the maximum vertical ground reaction forces between foot orthotic conditions. CONCLUSION: Generic use of off-the-shelf foot orthoses with medial arch support causes increased plantar forces and pressures on the fifth metatarsal and may increase the risk for proximal fracture of the fifth metatarsal. Future studies are needed to investigate this risk, acknowledging that the differences noted in our study were small in magnitude and the foot type was not measured.     

The relationship of the position of the metatarsal heads and peak plantar pressure

We test the premise that peak plantar pressure is located directly under the bony prominences in the forefoot region. The right foot of standing volunteers was examined in three different postures by a CT-scanner. The plantar pressure distribution was simultaneously recorded. The position of the metatarsal heads and the sesamoids could be related to the corresponding local peak plantar pressures. The metatarsal heads 1, 4, and 5 had a significantly different position than the local peak plantar pressures. The average difference in distance between the position of the metatarsal heads and the peak plantar pressure showed a significant correlation: on the medial side the head was located more distally to the local peak plantar pressure, on the lateral side more proximally. The findings suggest that normal plantar soft tissue is able to deflect a load. The observations might improve insight into the function of the normal forefoot and might direct further research on the pathological forefoot and on the design of footwear.     

Comparison of plantar pressure distribution in CAD–CAM and prefabricated foot orthoses in patients with flexible flatfeet

BackgroundsThe effect of foot orthoses on plantar pressure distribution has been proven by researchers but there are some controversies about advantages of custom-made foot orthoses to less expensive prefabricated foot orthoses.MethodsNineteen flatfeet adults between 18 and 45 participated in this study. CAD–CAM foot orthoses were made for these patients according to their foot scan. Prefabricated foot orthoses were prepared according to their foot size. Plantar pressure, force and contact area were measured using pedar^®-x in-shoe system wearing shoe alone, wearing CAD–CAM foot orthoses and wearing prefabricated foot orthoses. Repeated measures ANOVA model with post-hoc, Bonferroni comparison were used to test differences.ResultsCAD–CAM and prefabricated foot orthoses both decreased pressure and force under 2nd, 3–5 metatarsal and heel regions comparing to shoe alone condition. CAD–CAM foot orthosis increased pressure under lateral toe region in comparison to shoe alone and prefabricated foot orthosis. Both foot orthoses increased pressure and contact area in medial midfoot region comparing to shoe alone condition. Increased forces were seen at hallux and lateral toes by prefabricated foot orthoses in comparison with CAD–CAM foot orthoses and control condition, respectively.ConclusionAccording to the results, both foot orthoses could decrease the pressure under heel and metatarsal area. It seems that the special design of CAD–CAM foot orthoses could not make great differences in plantar pressure distribution in this sample. Further research is required to determine whether these results are associated with different scan systems or design software.     

Foot pressures during gait: a comparison of techniques for reducing pressure points

PURPOSE: Various methods have been used to redistribute plantar surface foot pressure in patients with foot ulcers. This study was conducted to determine the effectiveness of four modalities (fracture walker, fracture walker with insert, and open and closed toe total contact casts) in reducing plantar foot pressure. METHODS: Ten healthy, normal volunteer subjects had an F-scan sensor (ultra thin shoe insert pressure monitor) placed under the right foot. They then ambulated on a flat surface, maintaining their normal gait. Dynamic plantar pressures were averaged over 10 steps at four different sites (plantar surface of great toe, first metatarsal head, base of fifth metatarsal, and plantar heel). All subjects repeated this sequence under five different testing conditions (barefoot, with a fracture walker, fracture walker with arch support insert, open and closed toe total contact cast). Each subject's barefoot pressures were then compared with the pressures during the different modalities. RESULTS: All four treatment modalities significantly reduced (p < 0.05) plantar pressure at the first metatarsal head (no method was superior). The fracture walker, fracture walker with insert, and open toe total contact cast significantly reduced pressure at the heel. Pressures at the base of the fifth metatarsal and great toe were not significantly reduced with any treatment form. CONCLUSION: The fracture walker, with and without arch support, and total contact cast can effectively reduce plantar pressure at the heel and first metatarsal head.     

Neuromuscular Fatigue During 200 M Breaststroke

The aims of this study were: i) to analyze activation patterns of four upper limb muscles (duration of the active and non-active phase) in each lap of 200m breaststroke, ii) quantify neuromuscular fatigue, with kinematics and physiologic assessment. Surface electromyogram was collected for the biceps brachii, deltoid anterior, pectoralis major and triceps brachii of nine male swimmers performing a maximal 200m breaststroke trial. Swimming speed, SL, SR, SI decreased from the 1^st to the 3^rd lap. SR increased on the 4^th lap (35.91 ± 2.99 stroke·min^-1). Peak blood lactate was 13.02 ± 1.72 mmol·l^-1 three minutes after the maximal trial. The EMG average rectified value (ARV) increased at the end of the race for all selected muscles, but the deltoid anterior and pectoralis major in the 1^st lap and for biceps brachii, deltoid anterior and triceps brachii in the 4^th lap. The mean frequency of the power spectral density (MNF) decreased at the 4^th lap for all muscles. These findings suggest the occurrence of fatigue at the beginning of the 2^nd lap in the 200m breaststroke trial, characterized by changes in kinematic parameters and selective changes in upper limb muscle action. There was a trend towards a non-linear fatigue state.

Key Points

• Fatigue in the upper limbs occurs in different way as it described by 100m swimming events.
• Neuromuscular fatigue was estimated by analyzing the physiological changes (high blood lactate concentrations), biomechanical changes in the swimming stroke characteristics (decreased in swimming velocity), and by the changes in the EMG amplitude and frequency parameters at the end of the swimming bout.
• The amplitude signal of EMG provided by the ARV demonstrated an increase at the end with the respect to the beginning for all muscles under study, excepted for the muscle deltoid anterior.
• The mean frequency (MNF) in our study decrease at the end of the swimming in the 4^th lap relative to the 1^st lap for all muscles under observation, along the 200m breaststroke.

Key Words: Swimming, Kinematics, EMG, Mean frequency     

正常足与外翻足的足底压力研究

目的　对正常足与外翻足的足底压力进行测量。方法　运用自行研制的足底生物力学测试系统对30 名健康人60 足,45 例外翻患者89 足进行了行走时足底压力的测试。结果　重度外翻组31 足和正常组相比,第一跖骨头下压力明显减低( P< 0.001),第二跖骨头下压力明显增加(P< 0 .05),第三、五跖骨头下压力有增高的趋势。结论　正常人前足第一跖骨头下压力最高,并向外侧递减。重度外翻足前足第一跖骨头下压力明显减低,第二跖骨头下压力明显增高     

The effect of terrain on foot pressures during walking

BACKGROUND: High plantar pressures are associated with the development of foot ulcers in people with diabetic neuropathy. The effect of terrain on plantar pressures during walking has not been fully explored. METHODS: Twenty 23- to 40-year-old subjects with no known musculoskeletal pathology walked across three terrains: padded carpet (R), grass (G), and concrete (C) while wearing Novel Pedar (Novel Electronics Inc. GMBH, Munich, Germany) insoles with and without shoes. Pressures were collected at 50 Hz. The sole of the foot was divided into: heel (H), lateral midfoot (LM), medial midfoot (MM), big toe and first metatarsal head (BT), and lateral toes and metatarsal heads (LT). Repeated measures ANOVA identified differences in pressures, forces, and contact areas across terrains. Post hoc Bonferroni adjustments were used to accept an overall alpha level of 0.05. RESULTS: Peak pressure (PP), maximal mean pressure (MMP) and pressure time integral (PTI) were significantly higher (p < 0.01) when walking barefoot on concrete than on grass or carpet for all foot regions except MM and LM. The percent increase in the three pressure variables ranged from 21% to 43%. Grass and carpet PP, MMP, and PTI were similar for the BT and LT. Wearing shoes significantly increased contact area and decreased all pressure variables on all three terrains. CONCLUSION: Walking barefoot, especially on concrete was associated with higher plantar pressure variables. Wearing shoes eliminated terrain differences in pressure except under the lesser toes. Persons with insensate feet should avoid walking barefoot on hard surfaces to avoid excessive plantar pressures. Wearing shoes and covering hard floors with nonslip, padded rugs may decrease plantar pressures and the risk of ulceration.     

Adjusted Landing Technique Reduces the Load on the Achilles Tendon in Badminton Players

Achilles tendon (AT) rupture is common among recreational male badminton players. We hypothesize that a landing technique following forehand jump strokes with the landing foot in a neutral position often performed by recreational players and occasionally by elite players may expose the AT to higher loads than a scissor kick jump (SKJ) technique with the leg/foot externally rotated. The study aimed to investigate if recreational players could reduce the load in the AT when adopting the SKJ technique compared to their habitual landing technique with the foot in a neutral position and secondarily to compare the AT force between recreational players and elite players. Ten recreational male players performed simulated jump strokes in a biomechanical laboratory using both their original technique and the SKJ technique traditionally used by elite players. For comparison reasons ten elite players performed SKJs. Landing kinematics and AT forces were captured and calculated using 3D movement analysis. The landing leg was more externally rotated in the recreational players'' adjusted technique (78 ± 10 degrees, p < 0.001) compared to 22 ± 21 degrees in recreational players'' original technique. The peak AT force of the recreational players was significantly higher for the original technique compared to the adjusted technique (68 ± 19 N/kg vs. 50 ± 14 N/kg, p = 0.005). Additionally, the peak AT forces observed during the recreational players’ original technique was higher, though not significantly, than those observed for elite players (55 ± 11 N/kg, p = 0.017). / = 0.016 due to a Bonferroni correction. These findings indicate that recreational badminton players that normally land with the foot in a neutral position, may reduce their AT load by 25% when adopting the SKJ technique of elite players and land with the leg/foot in an externally rotated position. Key points

• The Achilles tendon load is influenced by the rotation of the lower leg when badminton players perform scissor kick jump on the rear court in badminton.
• The subgroup of recreational players in the present study reduced their AT landing forces significantly when adapting the scissor-kick jump technique, traditionally employed by elite players, without compromising performance parameters such as jump height.
• The AT landing forces of recreational badminton players who perform forehand jump strokes with minimum upper-body rotation, may exceed those elite players experience during scissor-kick jump landings.
• These findings suggest that badminton coaches should focus on upper-body rotation during forehand jump strokes to facilitate the external leg/foot position in the subsequent landing, to lower AT forces and potentially the risk of sustaining an AT injury.

Key words: Biomechanics, foot work, scissor kick jump     

Plantar pressures and relative lesser metatarsal lengths in older people with and without forefoot pain

Forefoot pain is a common problem in older people. We determined whether plantar pressures during gait and the relative lengths of the lesser metatarsals differ between older people with and without plantar forefoot pain. Dynamic plantar pressure assessment during walking was undertaken using the Tekscan MatScan® system in 118 community‐dwelling older people (44 males and 74 females), mean age 74 (standard deviation = 5.9) years, 43 (36%) of whom reported current or previous plantar forefoot pain. The relative lengths of metatarsals 1–5 were determined from weightbearing X‐rays. Participants with current or previous plantar forefoot pain exhibited significantly (p = 0.032) greater peak plantar pressure under metatarsal heads 3–5 (1.93 ± 0.41 kg/cm² vs. 1.74 ± 0.48 kg/cm²). However, no differences were found in relative metatarsal lengths between the groups. These findings indicate that older people with forefoot pain generate higher peak plantar pressures under the lateral metatarsal heads when walking, but do not exhibit relatively longer lesser metatarsals. Other factors may be responsible for the observed pressure increase, such as reduced range of motion of the metatarsophalangeal joints and increased stiffness of plantar soft tissues. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 427–433, 2013     

Ground Reaction Forces and Loading Rates Associated with Parkour and Traditional Drop Landing Techniques

Due to the relative infancy of Parkour there is currently a lack of empirical evidence on which to base specific technique instruction upon. The purpose of this study was to compare the ground reaction forces and loading rates involved in two Parkour landing techniques encouraged by local Parkour instructors and a traditional landing technique recommended in the literature. Ten male participants performed three different drop landing techniques (Parkour precision, Parkour roll, and traditional) onto a force plate. Compared to the traditional technique the Parkour precision technique demonstrated significantly less maximal vertical landing force (38%, p < 0.01, ES = 1.76) and landing loading rate (54%, p < 0.01, ES = 1.22). Similarly, less maximal vertical landing force (43%, p < 0.01, ES = 2.04) and landing loading rate (63%, p < 0.01, ES = 1.54) were observed in the Parkour roll technique compared to the traditional technique. It is unclear whether or not the Parkour precision technique produced lower landing forces and loading rates than the Parkour roll technique as no significant differences were found. The landing techniques encouraged by local Parkour instructors such as the precision and roll appear to be more appropriate for Parkour practitioners to perform than a traditional landing technique due to the lower landing forces and loading rates experienced.

Key points

• Parkour precision and Parkour roll landings were found to be safer than a traditional landing technique, resulting in lower maximal vertical forces, slower times to maximal vertical force and ultimately lesser loading rates.
• Parkour roll may be more appropriate (safer) to utilize than the Parkour precision during Parkour landing scenarios.
• The Parkour landing techniques investigated n this study may be beneficial for landing by non-Parkour practitioners in everyday life.

Key words: Kinetics, absorption, forefoot, roll.     

The effect of pre-fabricated insole on plantar pressure distribution in patients with rheumatoid arthritis

BackgroundFoot deformities result in pain and changes in plantar pressure distribution in rheumatoid arthritis (RA) patients. Medical insoles are commonly prescribed for declining pain and modifying foot pressure distribution in these patients. The purpose of this study was to evaluate the effect of a pre-fabricated insole with metatarsal pad and medial longitudinal arch support on plantar pressure distribution in rheumatoid arthritis patients.MethodsFifteen females with RA participated in this study. All patients received a pair of pre-fabricated insoles that were individually modified using metatarsal pads and medial longitudinal arch supports. Mean peak pressure (kPa), maximum force (N), and contact area (cm²) were calculated for the heel, midfoot, metatarsophalangeal joint, and toe regions using the Pedar-X system immediately and after a month follow-up.FindingsIn the heel and metatarsophalangeal joint regions, maximum pressure and force showed a significant reduction in the follow-up assessment (p < 0.05). The comparison showed a significant increase in maximum pressure and force in the midfoot when participants walked with insole compared to without insole condition (p < 0.001).InterpretationUsing a pre-fabricated insole with an individually modified metatarsal pad and medial longitudinal arch support could alter rheumatoid arthritis patients’ plantar pressures after one month of follow-up. This type of insole is simple and inexpensive and showed a significant effect on decreasing pressures under the metatarsal heads.     

Computer simulation of stress distribution in the metatarsals at different inversion landing angles using the finite element method

Metatarsal fracture is one of the most common foot injuries, particularly in athletes and soldiers, and is often associated with landing in inversion. An improved understanding of deformation of the metatarsals under inversion landing conditions is essential in the diagnosis and prevention of metatarsal injuries. In this work, a detailed three-dimensional (3D) finite element foot model was developed to investigate the effect of inversion positions on stress distribution and concentration within the metatarsals. The predicted plantar pressure distribution showed good agreement with data from controlled biomechanical tests. The deformation and stresses of the metatarsals during landing at different inversion angles (normal landing, 10 degree inversion and 20 degree inversion angles) were comparatively studied. The results showed that in the lateral metatarsals stress increased while in the medial metatarsals stress decreased with the angle of inversion. The peak stress point was found to be near the proximal part of the fifth metatarsal, which corresponds with reported clinical observations of metatarsal injuries.     

Fixed Foot Balance Training Increases Rectus Femoris Activation During Landing and Jump Height in Recreationally Active Women

The objective of this study was to determine the effects of fixed foot and functionally directed balance training on static balance time, muscle activation during landing, vertical jump height and sprint time. Twenty-four recreationally active females were tested pre- and post-training (fixed foot balance training, n= 11, functionally directed balance training, n = 7 and control group, n = 6). Experimental subjects completed either fixed foot or functionally directed balance exercises 4 times/week for 6 weeks. Surface electromyography (EMG) was used to assess preparatory and reactive muscle activity of the rectus femoris (RF), biceps femoris (BF), and the soleus during one- and two-foot landings following a jump. Maximum vertical jump height, static balance and 20-meter sprint times were also examined. The fixed foot balance-training group showed a 33% improvement (p < 0.05) in static balance time and 9% improvement in jump height. Neither type of training improved sprint times. Further analysis revealed significant (p < 0.05) overall (data collapsed over groups and legs) increases in reactive RF activity when landing. Independently, the fixed foot balance group showed a 33% increase in reactive RF activity (p < 0.01). Overall, there was also significantly less reactive co-activation following training (p < 0.05). It appears that fixed foot balance training for recreationally active women may provide greater RF activity when landing and increased countermovement jump height.

Key points

• Balance training increased rectus femoris EMG activity upon landing from a stride.
• Fixed foot balance training improved countermovement jump height.
• Neither fixed foot nor functionally directed balance training elicited changes in sprint times.

Key words: Balance training, muscle activation, training specificity     

Foot posture influences the electromyographic activity of selected lower limb muscles during gait

Background

Previous studies have suggested that increased plantar surface area, associated with pes planus, is a risk factor for the development of lower extremity overuse injuries. The intent of this study was to determine if a single or combination of foot anthropometric measures could be used to predict plantar surface area.

Methods

Six foot measurements were collected on 155 subjects (97 females, 58 males, mean age 24.5 ± 3.5 years). The measurements as well as one ratio were entered into a stepwise regression analysis to determine the optimal set of measurements associated with total plantar contact area either including or excluding the toe region. The predicted values were used to calculate plantar surface area and were compared to the actual values obtained dynamically using a pressure sensor platform.

Results

A three variable model was found to describe the relationship between the foot measures/ratio and total plantar contact area (R ² = 0.77, p < 0.0001)). A three variable model was also found to describe the relationship between the foot measures/ratio and plantar contact area minus the toe region (R ² = 0.76, p < 0.0001).

Conclusion

The results of this study indicate that the clinician can use a combination of simple, reliable, and time efficient foot anthropometric measurements to explain over 75% of the plantar surface contact area, either including or excluding the toe region.     

第1跖跗关节骨折脱位不同内固定方式对前足足底压力变化的影响

目的 :测量第1跖跗关节骨折脱位3种内固定对前足足底压力的变化,为选择内固定提供实验参考。方法:取8具新鲜足标本,制成第1跖跗关节骨折脱位模型,依次进行3.5 mm全螺纹皮质骨螺钉,1/4管形钢板及加压骑缝钉固定。经加载600 N后,通过F-scan足底压力分析系统,测量前足足底压力的变化。结果:第1跖跗关节骨折脱位后,第1跖骨头下的峰值压力将减小,而第2跖骨头下的峰值压力将增大,差异具有统计学意义(P<0.05)。对第1跖跗关节分别采用螺钉、钢板进行固定后,第1、2跖骨头下的峰值压力都将趋于正常状态,而进行骑缝钉固定后,虽然第1、2跖骨头下的峰值压力都有所恢复,但仍与正常状态比较,差异有统计学意义(P<0.05)。结论 :当第1跖跗关节骨折脱位后,邻近跖骨头可能存在着"负荷转移"的调节机制以代偿部分足底压力;当第1跖跗关节骨折脱位采用螺钉和钢板内固定治疗后,前足足底压力都可恢复至正常状态,而若采用骑缝钉固定,则前足足底压力仍难以恢复至正常状态。     

Effects of Combined Foot/Ankle Electromyostimulation and Resistance Training on the In-Shoe Plantar Pressure Patterns during Sprint in Young Athletes

Several studies have already reported that specific foot/ankle muscle reinforcement strategies induced strength and joint position sense performance enhancement. Nevertheless the effects of such protocols on sprint performance and plantar loading distribution have not been addressed yet. The objective of the study is to investigate the influence of a 5-wk foot/ankle strength training program on plantar loading characteristics during sprinting in adolescent males. Sixteen adolescent male athletes of a national training academy were randomly assigned to either a combined foot/ankle electromyostimulation and resistance training (FAST) or a control (C) group. FAST consisted of foot medial arch and extrinsic ankle muscles reinforcement exercises, whereas C maintained their usual training routine. Before and after training, in-shoe loading patterns were measured during 30-m running sprints using pressure sensitive insoles (right foot) and divided into nine regions for analysis. Although sprint times remained unchanged in both groups from pre- to post- training (3.90 ± 0.32 vs. 3.98 ± 0.46 s in FAST and 3.83 ± 0.42 vs. 3.81 ± 0.44 s in C), changes in force and pressure appeared from heel to forefoot between FAST and C. In FAST, mean pressure and force increased in the lateral heel area from pre- to post- training (67.1 ± 44.1 vs. 82.9 ± 28.6 kPa [p = 0.06]; 25.5 ± 17.8 vs. 34.1 ± 14.3 N [p = 0.05]) and did not change in the medial forefoot (151.0 ± 23.2 vs. 146.1 ± 30.0 kPa; 142.1 ± 29.4 vs. 136.0 ± 33.8; NS). Mean area increased in FAST under the lateral heel from pre- to post- (4.5 ± 1.3 vs. 5.7 ± 1.6 cm² [p < 0.05]) and remained unchanged in C (5.5 ± 2.8 vs. 5.0 ± 3.0 cm²). FAST program induced significant promising lateral and unwanted posterior transfer of the plantar loads without affecting significantly sprinting performance.

Key points

• We have evaluated the effects of a foot/ankle strength training program on sprint performance and on related plantar loading characteristics in teenage athletes, and this have not been examined previously.
• Our results showed no significant pre- to post- changes in sprint performance.
• This study revealed initially a lateral transfer and secondly a posterior transfer of the plantar loads after the foot/ankle strength training program.

Key words: Track and field, medial arch, reinforcement, injury prevention     

BioFoot in-shoe system: Normal values and assessment of the reliability and repeatability

BackgroundBioFoot^® is an in-shoe system to measure plantar pressures at the interface between the shoe and the sole of the foot. Since reliability and good repeatability are necessary to ensure the consistency of measurements on which clinical judgements are based, the aim of the study was to assess the reliability and repeatability of the BioFoot^® system and identify normal values for healthy subjects.Materials and methodsThirty subjects, 18 women and 12 men, were measured twice, with a 7–10 day interval between the sessions, wearing the same kind of shoes. In each session, three trials were recorded. The foot was divided into ten areas: heel, midfoot, whole forefoot, 1st–5th metatarsal heads, hallux, and lesser toes.ResultsThe intra-class correlation coefficients were between 0.76 and 0.96 for all four variables evaluated. The coefficient of variation between two sessions was around 7% (range: 4.6–9%). The mean contact time was 0.81 s, and walking cadence was 101.5 steps per minute. The pressure measurements showed the greatest peak and mean pressures under the second metatarsal head, and the second peak and mean pressures under the third metatarsal head.ConclusionThe plantar pressure measurements showed good to excellent consistency, and it was concluded that the BioFoot^® in-shoe system has good reliability and is repeatable. The highest values were found beneath the forefoot, which is consistent with the literature.