***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Muscle activity has previously been suggested to minimize soft-tissue resonance which occurs at heel-strike during walking and running . If this concept were true then the greatest vibration damping would occur when the input force was closest to the resonant frequency of the soft-tissues at heel-strike . However , this idea has not been tested . The purpose of this study was to test whether muscle activity in the lower extremity is used to damp soft-tissue resonance which occurs at heel-strike during walking . Hard and soft shoe conditions were tested in a r and omized block design .  Ground reaction forces , soft-tissue accelerations and myoelectric activity  were measured during  walking  for 40 subjects .  Soft-tissue mass was estimated from anthropologic measurements , allowing inertial forces in the soft-tissues to be calculated . The force transfer from the ground to the tissues was compared with changes in the muscle activity . The soft condition result ed in relative frequencies ( input/tissue ) to be closer to resonance for the main soft-tissue groups . However , no increase in force transmission was observed . Therefore , the vibration damping in the tissues must have increased . This increase concurred with increases in the muscle activity for the biceps femoris and lateral gastrocnemius . The evidence supports the proposal that muscle activity damps soft-tissue resonance at heel-strike . Muscles generate forces which act across the joints and , therefore , shoe design may be used to modify muscle activity and thus joint loading during walking and running The foot provides an important source of afferent feedback for balance and locomotion . Sensory feedback from the feet can be altered by st and ing or walking on different surfaces . The purpose was to determine the effects of textured footwear on lower extremity muscle activity , limb kinematics , and joint kinetics while walking . Three-dimensional kinematics and kinetics , as well as muscle EMG , were collected as subjects walked with a smooth and textured shoe insert .  Muscle activity was analyzed using a wavelet technique . The textured shoe insert caused a significant reduction in both soleus and tibialis anterior intensity during periods when these muscles are most active . Furthermore , the changes in muscle activity were only seen in the low frequency content of the EMG signal . The foot was significantly more plantar flexed at heel strike with the textured inserts . Small changes were also seen in vertical ground reaction forces and joint moments . It was assumed that the changes in gait patterns were due to a change in sensory feedback caused by the textured shoe insert . The possibilities of altered sensory feedback with footwear are discussed . Sensory feedback from the feet may affect specific motor unit pools during different activities . Changing the texture , without changing the geometry , of a shoe insert can alter muscle activity during walking . This may be useful in the prescription of footwear interventions and suggests that footwear may have sensory as well as mechanical effects Chronic Ankle Instability sprain causes are unclear and many factors or mechanisms may contribute to recurrence of this injury . The aim of the study was to investigate how an ankle destabilization device affects the EMG patterns of the ankle muscles during ankle stabilization against inversion . The left foot was equipped with a mechanical device mounted under the heel of the shoe . This mechanical device induces subtalar joint destabilization necessitating the control of ankle muscles . Surface electrodes were placed over the tibialis anterior , the peroneus longus , the peroneus brevis , the gastrocnemius lateral , and the gastrocnemius medial . Nine healthy subjects ( mean age 37+/-12 yr ; mean mass 68+/-17 kg ; mean height 1.73+/-0.7 m ) were instructed to walk normally along a tape fixed on the floor . The ankle destabilization device altered the walking pattern of all subjects . More specifically , the walking pattern is disturbed result ing in higher amplitude of the EMG activity of the peroneal muscles and the Tibialis Anterior and anticipatory reactions in the peroneal muscles . The results suggest that the ankle destabilization device could be beneficial for rehabilitation programs especially during the training of walking . Using this material may help to a specific reinforcement of muscles involved in anti-inversion ankle movement BACKGROUND To compare kinematics , kinetics and muscle activity during  st and ing and walking for healthy subjects using an  unstable test shoe  ( Masai Barefoot Technology , MBT ) and a stable control shoe . METHODS Eight subjects volunteered for this study . During quiet st and ing , center of pressure excursion and muscle activity were determined . During walking , lower extremity kinematics , kinetics , and muscle electromyographic ( EMG ) signals were determined . Data were collected for the two shoe conditions after a 2week accommodation period . Statistics included repeated measures ANOVAs ( alpha = 0.05 ) and post hoc tests where appropriate . FINDINGS During quiet st and ing , the center of pressure excursion was significantly and substantially greater in the unstable compared to the control shoe . Electromyographic intensity increased in the unstable test shoe for all tested muscles , but only significantly for the tibialis anterior . During locomotion , kinematics were similar in the two shoe conditions except for the initial plantar-dorsiflexion , which showed a significant more dorsiflexed position during the first half of stance in the unstable test shoe compared to the stable control shoe . The angular impulses did not show any significant differences between the two shoe conditions for all three joints but some trends towards a reduction for the knee and hip joint . There were no significant differences in electromyographic activities between the control and the unstable shoe . However , several muscles showed some trends . INTERPRETATION The unstable shoe produced changes and trends in kinematic , kinetic and electromyographic characteristics that seemed to be advantageous for the locomotor system . Further studies should investigate muscle strength , dynamic stability , pain reduction for arthritic knees and injury prevention for high performance athletes when using the unstable shoes OBJECTIVE The purpose of this study was to determine if  high-arched and low-arched runners exhibit different injury patterns . DESIGN Non-r and omized , two-group injury survey . BACKGROUND Running-related injuries are thought to be related , in part , to lower extremity structure . High-arched and low-arched  runners with their different bony architecture may exhibit very different lower extremity mechanics and , consequently , different injury patterns . It was hypothesized that high-arched runners will exhibit a greater incidence of lateral injuries , skeletal injuries and knee injuries while low-arched runners will show a greater incidence of medial injuries , soft tissue injuries and foot injuries . METHODS Twenty high-arched and 20 low-arched runners were included in this study . Running-related injuries were recorded and divided into injury patterns of medial/lateral , bony/soft tissue and knee/foot and ankle for both high-arched and low-arched runners . A chi(2 ) analysis was then employed in an attempt to associate injury patterns with arch structure . RESULTS High-arched runners reported a greater incidence of ankle injuries , bony injuries and lateral injuries . Low-arched runners exhibited more knee injuries , soft tissue injuries and medial injuries . CONCLUSIONS Based on these results , high and low arch structure is associated with different injury patterns in runners . Relevance . Different injury patterns are present in individuals with extreme high arches when compared to those with extremely low arches . These relationships may lead to improved treatment and intervention strategies for runners based on their predisposing foot structure Abnormal foot morphology has been suggested to contribute to overuse injuries in athletes . This study investigated the relationship between foot type and injury incidence in a large sample of competitive triathletes not wearing foot orthoses during a 6-month retrospective analysis and a 10-week prospect i ve cohort study .  Foot alignment was measured using the  Foot Posture Index and the Valgus Index  , and participants were assigned to supinated , pronated , and normal foot-type groups . Overall , 131 triathletes sustained 155 injuries during the study . Generally , foot type was not a major risk factor for injury ; however , there was a fourfold increased risk of overuse injury during the competition season in athletes with a supinated foot type . The results of this study show that triathletes with a supinated foot type are more likely to sustain an overuse injury OBJECTIVE : To test the feasibility of creating a valid and reliable checklist with the following features : appropriate for assessing both r and omised and non-r and omised studies ; provision of both an overall score for study quality and a profile of scores not only for the quality of reporting , internal validity ( bias and confounding ) and power , but also for external validity . DESIGN : A pilot version was first developed , based on epidemiological principles , review s , and existing checklists for r and omised studies . Face and content validity were assessed by three experienced review ers and reliability was determined using two raters assessing 10 r and omised and 10 non-r and omised studies . Using different raters , the checklist was revised and tested for internal consistency ( Kuder-Richardson 20 ) , test-retest and inter-rater reliability ( Spearman correlation coefficient and sign rank test ; kappa statistics ) , criterion validity , and respondent burden . MAIN RESULTS : The performance of the checklist improved considerably after revision of a pilot version . The Quality Index had high internal consistency ( KR-20 : 0.89 ) as did the subscales apart from external validity ( KR-20 : 0.54 ) . Test-retest ( r 0.88 ) and inter-rater ( r 0.75 ) reliability of the Quality Index were good . Reliability of the subscales varied from good ( bias ) to poor ( external validity ) . The Quality Index correlated highly with an existing , established instrument for assessing r and omised studies ( r 0.90 ) . There was little difference between its performance with non-r and omised and with r and omised studies . Raters took about 20 minutes to assess each paper ( range 10 to 45 minutes ) . CONCLUSIONS : This study has shown that it is feasible to develop a checklist that can be used to assess the method ological quality not only of r and omised controlled trials but also non-r and omised studies . It has also shown that it is possible to produce a checklist that provides a profile of the paper , alerting review ers to its particular method ological strengths and weaknesses . Further work is required to improve the checklist and the training of raters in the assessment of external validity Over-pronation has been cited as a key contributor to many types of running injuries . However , the roles of the extrinsic foot muscles during running have not been adequately identified . The purpose of this study was to examine the muscle functional ( mf ) MRI and EMG responses to perturbations of the foot by running in varus , neutral and valgus wedged shoes . Ten males ran at 3.6 m/s in specially constructed shoes for 5 min with T2-weighted mfMRI collected before and after each run . The change in T2 from before to after each run characterized the level of metabolic activity in each of muscle . Kinematic and EMG data were also collected while subjects ran on a treadmill . There were no T2 differences across the three shoe conditions . In contrast , there was significantly less EMG activity in the tibialis anterior and soleus while wearing the neutral shoe . Overall , the results did not support the theory that muscle activity would increase as the degree of eversion increased . It also appears that surface EMG was more sensitive to differences between conditions than mfMRI . However , this study illustrated that mfMRI may be a useful tool for quantifying muscle activity in cases where surface EMG is inadequate OBJECTIVE To compare walking stance phase rearfoot and forefoot motion , ankle joint moments and extrinsic foot muscle EMG profiles between normal and pes planus feet . DESIGN A cross-sectional comparative study . BACKGROUND Musculoskeletal conditions are often attributed to pes planus , in which motion is assumed to be excessive and the muscle control inadequate . However , many of the speculated differences in mechanics and control between the normal and the pes planus foot have not been quantified . METHODS Kinematic and kinetic data were obtained from video recordings of skin surface markers and a force plate , and EMG was recorded with surface electrodes . Analysis of variance was carried out to compare the group profiles . RESULTS In the pes planus group : the forefoot was less adducted ( P < .05 ) at toe-off , and total transverse plane range of motion , at 8 degrees versus 10 degrees , was less ( P < .01 ) ; the peak plantarflexor ankle moment at push-off was greater ( P < .05 ) ; the invertor moment was greater at foot flat ( P < .05 ) ; for the EMG profiles , activity early in stance , relative to the mean stance phase activity was higher ( P < .01 ) in tibialis anterior and lower ( P < .05 ) in the peronei , soleus and medial and lateral gastrocnemius . CONCLUSIONS Despite reaching statistical significance , the group differences were small for the task of laboratory walking at a natural pace . The main implication s of the differences were for restraint of motion . The expectations of excessive motion and muscle effort in the pes planus group were therefore not substantiated . RELEVANCE Symptomatic pes planus subjects did not reveal the expected biomechanical differences from normal subjects . The underlying causes of symptoms were not identifiable Purpose To identify the incidence of medial tibial stress syndrome ( MTSS ) in a group of naval recruits undergoing a 10-week basic training period and to determine potential risk factors . Method One hundred and twenty-four recruits ( 84 men and 40 women ) were followed prospect ively during basic training .  Anthropometric and lower limb biomechanical data were recorded at the start of the program along with injury history and previous sporting activity for the 3 months prior to enlisting . Recruits were monitored during training for development of medial tibial strees syndrome and were asked to complete an exit interview at the end of the program . Results Forty recruits ( 22 men and 18 women ) developed medial tibial stress syndrome , giving an incidence of 35 % . A significant relationship existed between gender and medial tibial stress syndrome ( P= .012 ) 
    Output:
    
Some evidence exists that : ( i ) pronated feet demonstrate greater electromyographic activation of invertor musculature and decreased activation of evertor musculature ; ( ii ) foot orthoses increase activation of tibialis anterior and peroneus longus , and may alter low back muscle activity ; and ( iii ) shoes with elevated heels alter lower limb and back muscle activation .
Most studies reported statistically significant changes in electromyographic activation , although these findings were often not well supported when confidence intervals were calculated .