Barefoot and shod running: their effects on foot muscle kinetics

Running shoe technology has advanced significantly in the last 50 years, although the overall injury rate has yet to decrease. Barefoot (BF) running has become increasing more popular in the last 10 years. The current investigation aimed to explore differences in the forces produced by the foot muscles during BF and shod (SH) running. Fifteen male participants ran at 4.0 m.s-1 (± 5%). Kinematics were measured using an eight-camera motion analysis system alongside ground reaction forces. Peak and average stance phase forces from the flexor digitorum longus (FDL), flexor hallucis longus (FHL), peroneus longus (PL), extensor digitorum longus (EDL) and extensor hallucis longus (EHL) muscles were obtained using OpenSim v3.2. Peak and average forces of the FDL, FHL and PL muscles were significantly larger when running BF, whereas peak and average forces of the FHL and EHL muscles were significantly larger when running SH. This study supports the conjecture that the plantar muscles are required to work harder when running BF in relation to SH, indicating that BF training may serve to strengthen the foot musculature

Side to side differences in hamstring muscle kinematics during maximal instep soccer kicking

Hamstring strains are a common non-contact injury in soccer. The current study investigates bilateral differences in hamstring kinematics during maximal instep kicking. Thirteen male soccer players performed maximal instep kicks with their dominant and non-dominant limbs. Muscle-tendon kinematics of the four hamstring muscles during the kick movement were quantified using OpenSim software. Differences between dominant and non-dominant limbs were examined using paired t-tests. The results revealed that the biceps femoris long head (dominant = 165.28. ± 62.46 & non-dominant = 137.65 ± 52.17%), semimembranosus (dominant = 220.75 ± 43.35 & non-dominant = 131.23 ± 36.74%) and semitendinosus (dominant = 90.95 ± 16.69% and non-dominant = 80.47 ± 15.99%) experienced significantly greater strain when using the dominant limb. The current investigation provides key information regarding the mechanics of the hamstring group during maximal instep kicking, indicating that kicking with the dominant limb may place soccer players at increased risk from hamstring strain injury

Gender differences in limb and joint stiffness during the fencing lunge

The aim of the current investigation was to examine gender differences in limb and joint stiffness characteristics during the fencing lunge. Ten male and ten female fencers completed simulated lunge movements. Lower limb kinematics were collected using an eight camera optoelectric motion capture system which operated at 250 Hz. Measures of limb and joint stiffness were calculated as a function of limb length and joint moments divided by the extent of limb and joint excursion. Gender differences in limb joint stiffness parameters were examined statistically using independent samples t-tests. The results showed firstly that both limb (male = 64.22 ±19.12, female = 75.09 ±22.15 N.kg.m) and hip stiffness (male = 10.50 ±6.00, female = 25.89 ±15.01 Nm.kg.rad) were significantly greater in female fencers. In addition it was also demonstrated that knee moment (male = 1.64 ±0.23, female = 2.00 ±0.75 Nm.kg) was significantly larger in females. On the basis of these observations, the findings from the current investigation may provide further insight into the aetiology of the distinct injury patterns observed between genders in relation to fencing

The influence of barefoot and shod running on Triceps-surae muscle strain characteristics

The aim of the current investigation was to determine the effects of barefoot and shod running on the kinematics of the Triceps-Surae muscle group. Twelve male participants ran at 4.0 m.s-1 (± 5%) in both barefoot and shod conditions. Kinematics were measured using an eight-camera motion analysis system. Muscle kinematics from the lateral Gastrocnemius, medial Gastrocnemius and Soleus were obtained using musculoskeletal modelling software (Opensim v3.2). The results showed that muscle strain for the lateral Gastrocnemius (barefoot = 1.10 & shod = 0.33 %), medial Gastrocnemius (barefoot = 1.07 & shod = 0.32 %) and Soleus (barefoot = 3.43 & shod = 2.18 %) were significantly larger for the barefoot condition. Given the proposed association between the extent of muscle strain and the etiology of chronic muscle strain pathologies, the current investigation shows that running barefoot may place runners at greater risk from Triceps-Surae strain injuries

The effect of minimalist, maximalist and energy return footwear of equal mass on running economy and substrate utilization

The aim of the current study was to explore the effects of minimalist, maximalist and energy return footwear of equal mass on economy and substrate utilisation during steady state running. Ten male runners completed 6 min steady state runs in minimalist, maximalist and energy return footwear. The mass of the footwear was controlled by adding lead tape to the lighter shoes. Running economy, shoe comfort, rating of perceived exertion and % contribution of carbohydrate to total calorie expenditure were assessed. Participants also subjectively indicated which shoe condition they preferred for running. Differences in shoe comfort and physiological parameters were examined using paired samples t-tests, whilst shoe preferences were tested using a chi-square test. The results showed firstly that running economy was significantly improved in the energy return (35.9 ml∙kg/min) compared to minimalist footwear (37.8 ml∙kg/min). In addition % carbohydrate was significantly greater in the minimalist (76.4%) in comparison to energy return footwear (72.9%). As running economy was improved and carbohydrate utilisation reduced in the energy return in comparison to minimalist footwear, the current investigation shows that these footwear are more economical when shoe mass is controlled

Multi-segment foot kinematics and plantar fascia strain during treadmill and overground running

Although physiologically beneficial, running is known to be associated with a high incidence of chronic injuries. Excessive coronal and transverse plane motions of the foot segments and strain experienced by the plantar fascia are linked to the development of a number of chronic injuries. This study examined differences in multi-segment foot kinematics and plantar fascia strain during treadmill and overground running. Twelve male recreational runners ran at 4.0 m.s-1 in both treadmill and overground conditions. Multi-segment foot kinematics and plantar fascia strain were measured using an eight-camera motion analysis system and contrasted using paired samples t-tests. The results showed that plantar fascia strain was significantly greater in the overground condition (8.23 ± 2.77) compared to the treadmill (5.53 ± 2.25). Given the proposed relationship between excessive plantar fascia strain and the etiology of injury, overground running may be associated with a higher incidence of injury although further work is necessary before causation can be confirmed

Effects of new military footwear on knee loading during running

Military recruits are known to be susceptible to chronic injuries. The knee is the most common injury site and patellofemoral pain has been demonstrated as the leading mechanism for medical military discharge. Military boots have been cited as a key mechanism responsible for the high incidence of chronic injuries. The British Army has therefore introduced two new footwears – a cross-trainer and running shoe to reduce the incidence of chronic injuries. The aim of this study was to compare knee joint kinetics of the cross-trainer and running shoe in relation to conventional military boots. Twelve male participants ran at 4.0 m s−1 in each footwear condition. Knee joint kinetics was obtained and contrasted using repeated-measures ANOVAs. The results showed that patellofemoral load was significantly greater in the military boots. However, peak knee abduction moment was significantly greater in the running shoes. On the basis of the findings from this study, it is recommended that recruits who are susceptible to injuries mediated through excessive knee loads select the cross-trainer for their running activities

Effects of minimalist and maximalist footwear on Achilles tendon load in recreational runners

The current investigation aimed to comparatively examine the effects of minimalist, maximalist and conventional footwear on Achilles tendon forces (ATF) during running. Twelve male runners (age 23.11±5.01 years, height 1.78±0.10 cm and body mass 77.13±7.89 kg) ran at 4.0 m/s in the three footwear conditions. ATF’s were calculated using Opensim software allowing the magnitudal and temporal aspects of the ATF to be quantified. Differences between footwear were examined using one-way repeated measures ANOVA. The results showed the peak ATF was significantly larger in minimalist footwear (5.97±1.38 body weight (BW)) compared to maximalist (5.07±1.42 BW). In addition it was revealed that ATF per mile was significantly larger in minimalist (492.31±157.72 BW) in comparison to both maximalist (377.31±148.06 BW) and conventional (402.71±125.51 BW) footwear. Given the relationship between high ATF and Achilles tendon degradation, the current investigation indicated that minimalist footwear may increase runners risk for Achilles tendon injury

Sex Differences in Shock Attenuation during Running

The current investigation was conducted to determine whether sex differences in skeletal accelerations and shock attenuation were evident during running. Twelve male and twelve female recreational runners ran at 4.0 m.s -1. Axial accelerations were measured at 1,000 Hz using accelerometers mounted at the tibia and sacrum. Peak tibial and sacrum axial accelerations were obtained and utilized to calculate the extent of shock attenuation. The results showed that peak sacrum accelerations were significantly larger in female runners (5.16 ±0.64 g) compared to males (4.37 ±0.75 g). It was also shown that shock attenuation (31.90 ±19.85%) was significantly lower in female runners in relation to males (47.89 ±11.46%). The findings from the current investigation indicate that female runners experience greater skeletal accelerations which may place greater stress on the musculoskeletal structures required attenuate transients forces which can be detrimental to passive tissue

Effects of a 10 week footstrike transition in habitual rearfoot runners with patellofemoral pain

Patellofemoral pain is the most common pathology in runners. Mid/fore foot runners experience lower patellofemoral loading compared to those who use a rearfoot strike. The aim of this study was to examine the efficacy of a 10-week intervention allowing runners with patellofemoral pain to transition from a rearfoot strike pattern. Nine male runners with patellofemoral pain were given a graduated 10-week program which allowed them to convert their habitual rearfoot strike pattern. Lower extremity kinematics, tibial accelerations, loading rates, patellofemoral kinetics and Achilles tendon kinetics were collected. Self-reported knee and Achilles tendon pain were examined using the Knee injury and Osteoarthritis Outcome Score and numeric pain rating scale. Data were collected before and after the 10-week transition. Reductions were found in peak patellofemoral force/ pressure (pre transition = 4.76BW & 13.10MPa & post transition = 4.27BW & 11.48MPa). Improvements were shown for Knee injury and Osteoarthritis Outcome Score subscales pain (pre transition = 62.04 & post transition = 78.41), sport (pre transition = 53.61 & post transition = 72.67), function and daily living (pre transition = 67.68 & post transition = 80.08). Increases were however found for peak Achilles tendon force (pre transition = 5.07BW & post transition = 5.58BW) and Achilles tendon pain (pre transition = 1.06 & post transition = 2.67). Transitioning from a rearfoot strike pattern reduces patellofemoral loading and pain symptoms. The key implication is that rearfoot strike runners with patellofemoral pain can reduce their pain symptoms by altering their footstrike pattern; although this may be at the expense of increased pain at the Achilles tendon