Injury risk in runners using standard or motion control shoes: a randomised controlled trial with participant and assessor blinding.

BACKGROUND/AIM: This randomised controlled trial investigated if the usage of running shoes with a motion control system modifies injury risk in regular leisure-time runners compared to standard shoes, and if this influence depends on foot morphology. METHODS: Recreational runners (n=372) were given either the motion control or the standard version of a regular running shoe model and were followed up for 6 months regarding running activity and injury. Foot morphology was analysed using the Foot Posture Index method. Cox regression analyses were used to compare injury risk between the two groups, based on HRs and their 95% CIs, controlling for potential confounders. Stratified analyses were conducted to evaluate the effect of motion control system in runners with supinated, neutral and pronated feet. RESULTS: The overall injury risk was lower among the participants who had received motion control shoes (HR=0.55; 95% CI 0.36 to 0.85) compared to those receiving standard shoes. This positive effect was only observed in the stratum of runners with pronated feet (n=94; HR=0.34; 95% CI 0.13 to 0.84); there was no difference in runners with neutral (n=218; HR=0.78; 95% CI 0.44 to 1.37) or supinated feet (n=60; HR=0.59; 95% CI 0.20 to 1.73). Runners with pronated feet using standard shoes had a higher injury risk compared to those with neutral feet (HR=1.80; 95% CI 1.01 to 3.22). CONCLUSIONS: The overall injury risk was lower in participants who had received motion control shoes. Based on secondary analysis, those with pronated feet may benefit most from this shoe type.

Shoe drop has opposite influence on running pattern when running overground or on a treadmill.

PURPOSE: Minimalist running shoes are designed to induce a foot strike made more with the forepart of the foot. The main changes made on minimalist shoe consist in decreasing the height difference between fore and rear parts of the sole (drop). Barefoot and shod running have been widely compared on overground or treadmill these last years, but the key characteristic effects of minimalist shoes have been yet little studied. The purpose of this study is to find whether the shoe drop has the same effect regardless of the task: overground or treadmill running. METHODS: Twelve healthy male subjects ran with three shoes of different drops (0, 4, 8 mm) and barefoot on a treadmill and overground. Vertical ground reaction force (vGRF) (transient peak and loading rate) and lower limb kinematics (foot, ankle and knee joint flexion angles) were observed. RESULTS: Opposite footwear effects on loading rate between the tasks were observed. Barefoot running induced higher loading rates during overground running than the highest drop condition, while it was the opposite during treadmill running. Ankle plantar flexion and knee flexion angles at touchdown were higher during treadmill than overground running for all conditions, except for barefoot which did not show any difference between the tasks. CONCLUSIONS: Shoe drop appears to be a key parameter influencing running pattern, but its effects on vGRF differ depending on the task (treadmill vs. overground running) and must be considered with caution. Unlike shod conditions, kinematics of barefoot condition was not altered by treadmill running explaining opposite conclusions between the tasks.

Aging of running shoes and its effect on mechanical and biomechanical variables: implications for runners.

This study investigates the effect of running shoes' aging on mechanical and biomechanical parameters as a function of midsole materials (viscous, intermediate, elastic) and ground inclination. To this aim, heel area of the shoe (under calcaneal tuberosity) was first mechanically aged at realistic frequency and impact magnitudes based on a 660 km training plan. Stiffness (ST) and viscosity were then measured on both aged and matching new shoes, and repercussions on biomechanical variables (joint kinematics, muscular pre-activation, vertical ground reaction force and tibial acceleration) were assessed during a leg-extended stepping-down task designed to mimic the characteristics of running impacts. Shoes' aging led to increased ST (means: from 127 to 154 N ∙ mm(-1)) and decreased energy dissipation (viscosity) (means: from 2.19 to 1.88 J). The effects induced by mechanical changes on body kinematics were very small. However, they led with the elastic shoe to increased vastus lateralis pre-activation, tibial acceleration peak (means: from 4.5 g to 5.2 g) and rate. Among the three shoes tested, the shoe with intermediate midsole foam provided the best compromise between viscosity and elasticity. The optimum balance remains to be found for the design of shoes regarding at once cushioning, durability and injury prevention.

Adaptation of running pattern to the drop of standard cushioned shoes: A randomised controlled trial with a 6-month follow-up.

OBJECTIVES: While several cross-sectional studies have investigated the acute effects of shoe drop on running biomechanics, the long-term consequences are currently unknown. This study aimed to investigate if the drop of standard cushioned shoes induces specific adaptations in running technique over a six-month period in leisure-time runners. DESIGN: Double-blinded randomised controlled trial. METHODS: The participants (n=59) received a pair of shoes with a heel-to-toe drop of 10mm (D10), 6mm (D6) or 0mm (D0) and were followed-up regarding running training over 6 months or 500km, whichever came first. Spatio-temporal variables and kinematics (foot/ground, ankle and knee joint angles) were investigated while running at preferred speed on a treadmill before and after the follow-up. RESULTS: The participants ran 332±178km in the study shoes between pre- and post-tests. There was no shoe version by time interaction for any of the spatio-temporal variables nor for lower limb angles at initial ground contact. A small but significant shoe drop effect was found for knee abduction at mid-stance (p=0.032), as it decreased for the D0 version (-0.3±3.1 vs. -1.3±2.6°) while it increased for the D6 (0.3±2.7 vs. 1.3±3.1°) and D10 version (-0.2±3.2 vs. 0.5±3.1°). However, none of the pairwise comparisons was significant in the post-hoc analysis. CONCLUSIONS: Apart from knee abduction at mid-stance, no specific adaptation in spatio-temporal variables and kinematics was found between the three shoe versions during this 6-month follow-up. Thus, shoe drop of standard cushioned shoes does not seem to influence running biomechanics in the long term.

Influence of the Heel-to-Toe Drop of Standard Cushioned Running Shoes on Injury Risk in Leisure-Time Runners: A Randomized Controlled Trial With 6-Month Follow-up.

BACKGROUND: Modern running shoes are available in a wide range of heel-to-toe drops (ie, the height difference between the forward and rear parts of the inside of the shoe). While shoe drop has been shown to influence strike pattern, its effect on injury risk has never been investigated. Therefore, the reasons for such variety in this parameter are unclear. PURPOSE: The first aim of this study was to determine whether the drop of standard cushioned running shoes influences running injury risk. The secondary aim was to investigate whether recent running regularity modifies the relationship between shoe drop and injury risk. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: Leisure-time runners (N = 553) were observed for 6 months after having received a pair of shoes with a heel-to-toe drop of 10 mm (D10), 6 mm (D6), or 0 mm (D0). All participants reported their running activities and injuries (time-loss definition, at least 1 day) in an electronic system. Cox regression analyses were used to compare injury risk between the 3 groups based on hazard rate ratios (HRs) and their 95% CIs. A stratified analysis was conducted to evaluate the effect of shoe drop in occasional runners (<6 months of weekly practice over the previous 12 months) versus regular runners (≥6 months). RESULTS: The overall injury risk was not different among the participants who had received the D6 (HR, 1.30; 95% CI, 0.86-1.98) or D0 (HR, 1.17; 95% CI, 0.76-1.80) versions compared with the D10 shoes. After stratification according to running regularity, low-drop shoes (D6 and D0) were found to be associated with a lower injury risk in occasional runners (HR, 0.48; 95% CI, 0.23-0.98), whereas these shoes were associated with a higher injury risk in regular runners (HR, 1.67; 95% CI, 1.07-2.62). CONCLUSION: Overall, injury risk was not modified by the drop of standard cushioned running shoes. However, low-drop shoes could be more hazardous for regular runners, while these shoes seem to be preferable for occasional runners to limit injury risk.

Does wearing shoes affect your biomechanical efficiency?

Studies involving minimalist shoes have dramatically increased this past 10 years. While a deeper knowledge of the related modifications has ensued regarding the kinematics, electromyographic, and dynamic patterns, little is known regarding the modifications at the muscle forces and muscle fiber levels. The aim of the present study was to assess at a muscular level the modifications brought up when running barefoot, using 0mm midsole height running shoe, or using classical midsole height running shoes. An EMG-Driven model that combines the kinematics, dynamics, and electromyographic data was used to estimate the Triceps Surae (TS) muscle forces and fiber behavior during running using different footwear conditions. Despite differences at the joint level between barefoot and shod running when looking at ankle joint range of motion, or foot-ground angle at touchdown, the results showed no effect of footwear neither on the maximal muscle forces nor on the relative amount of force produced by each muscle within the TS muscle group when wearing different footwear. On the contrary, different behaviors of muscle fibers were shown with lower amplitudes of fiber lengths for the Gastrocnemii biarticular muscles when running barefoot. This particular results reveal that wearing a shoe, even with a very thin sole, could deeply modify the intricate muscle-tendon mechanics of running.

Is midsole thickness a key parameter for the running pattern?

Many studies have highlighted differences in foot strike pattern comparing habitually shod runners who ran barefoot and with running shoes. Barefoot running results in a flatter foot landing and in a decreased vertical ground reaction force compared to shod running. The aim of this study was to investigate one possible parameter influencing running pattern: the midsole thickness. Fifteen participants ran overground at 3.3 ms(-1) barefoot and with five shoes of different midsole thickness (0 mm, 2 mm, 4 mm, 8 mm, 16 mm) with no difference of height between rearfoot and forefoot. Impact magnitude was evaluated using transient peak of vertical ground reaction force, loading rate, tibial acceleration peak and rate. Hip, knee and ankle flexion angles were computed at touch-down and during stance phase (range of motion and maximum values). External net joint moments and stiffness for hip, knee and ankle joints were also observed as well as global leg stiffness. No significant effect of midsole thickness was observed on ground reaction force and tibial acceleration. However, the contact time increased with midsole thickness. Barefoot running compared to shod running induced ankle in plantar flexion at touch-down, higher ankle dorsiflexion and lower knee flexion during stance phase. These adjustments are suspected to explain the absence of difference on ground reaction force and tibial acceleration. This study showed that the presence of very thin footwear upper and sole was sufficient to significantly influence the running pattern.