***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: Dimensionless analysis ensures that differences in sizes ( e.g. height and weight ) of children have a minimal influence on gait parameters . The results of changes in speed on gait parameters were examined using dimensionless analysis on data from a prospect i ve 5-year study of 16 children .  Linear regression analysis of peak and trough values of temporal distance parameters , ground reaction forces , joint angles , moments and powers provide a quantitative description of gait development with normalised speed . These linear relationships can be used to estimate gait parameters from speed measurements for normal subjects . However , caution is advised in using the data to attempt to predict an individual 's gait parameters due to the wide spread of data about the regression lines and we do not recommend that the data be used to extrapolate the regression data to wider speed ranges Here we share a rich gait data set collected from fifteen subjects walking at three speeds on an instrumented treadmill .  Each trial consists of 120 s of normal walking and 480 s of walking while being longitudinally perturbed during each stance phase with pseudo-r and om fluctuations in the speed of the treadmill belt . A total of approximately 1.5 h of normal walking ( > 5000 gait cycles ) and 6 h of perturbed walking ( > 20,000 gait cycles ) is included in the data set . We provide full body marker trajectories and ground reaction loads in addition to a presentation of processed data that includes gait events , 2D joint angles , angular rates , and joint torques along with the open source software used for the computations . The protocol is described in detail and supported with additional elaborate meta data for each trial . This data can likely be useful for validating or generating mathematical models that are capable of simulating normal periodic gait and non-periodic , perturbed gaits [ Purpose ] The purpose of this study was to investigate the changes in hip , knee and ankle kinematic variables of the lower extremities at different gait speeds . [ Subjects and Methods ] Forty healthy subjects who had no previous history of neurological , musculo-skeletal or other medical conditions that could affect gait were recruited . The subjects were asked to walk 10 m down a walkway at three different gait speeds : normal gait speed , and self-selected fast , and slow speeds . The experimental order was r and omly chosen across these gaits . The  hip , knee and ankle kinematic data were evaluated using a VICON 3D motion analysis system and force plates . [ Results ] The flexion peak and external rotation peak of the knee joint significantly increased with the increase of gait speed . The plantarflexion peaks of the ankle joint significantly increased with increase of gait speed . However , none of the kinematic data of the hip joint were significantly dependent on increase of gait speed . [ Conclusion ] The relationship of the knee and ankle joint can be described as coupling motion which is dependent on gait speed . Our present findings suggest that coupling motion of the knee joint and plantarflexion of the ankle joint significantly increase with increase of gait speed . These results will provide important insight into gait mechanisms for the evaluation of pathological population Background It is not well understood why one in five patients report poor outcomes following knee arthroplasty . This study evaluated changes in knee biomechanics , and perceived pain among patients reporting either a good or a poor outcome in knee-related quality of life after total knee arthroplasty . Methods Twenty-eight patients ( mean age 66 ( SD 7 ) years ) were included in this prospect i ve study . Within one month of knee arthroplasty and one year after surgery , patients underwent three-dimensional ( 3D ) gait analysis , completed the Knee Injury and Osteoarthritis Outcome Score ( KOOS ) , and rated perceived pain using a visual analogue scale . A “ good outcome ” was defined as a change greater than the minimally detectable change in the KOOS knee-related quality of life , and a “ poor outcome ” was defined as change below the minimally detectable change . Nineteen patients ( 68 % ) were classified as having a good outcome . Groups were analyzed separately and knee biomechanics were compared using a two-way repeated measures ANOVA . Differences in pain between groups were evaluated using Mann Whitney U test . Results Patients classified as having a good outcome improved significantly in most knee gait biomechanical outcomes including increased knee flexion-extension range , reduced peak varus angle , increased peak flexion moment , and reduced peak valgus moment . The good outcome group also displayed a significant increase in walking speed , a reduction ( normalization ) of stance phase duration ( % of gait cycle ) and increased passive knee extension . Whereas , the only change in knee biomechanics , one year after surgery , for patients classified as having a poor outcome was a significant reduction in peak varus angle . No differences in pain postoperatively were found between groups . Conclusion Patients reporting a good outcome in knee-related quality  of life improved in knee biomechanics during gait , while patients reporting a poor outcome , despite similar reduction in pain , remained unchanged in knee biomechanics one year after total knee arthroplasty . With regards to surgeon-controlled biomechanical factors , surgery may most successfully address frontal plane knee alignment . However , achieving a good outcome in patient-reported knee-related quality of life may be related to dynamic improvements in the sagittal plane This study obtained measurements of the spatiotemporal gait parameters of healthy young adult Kuwaiti subjects from both genders and compared the data to those collected in a similar study performed in Sweden . Thirty healthy subjects volunteered to participate in the study ( which included being asked to walk at their " free , " " slow , " and " fast " self-selected speeds ) . We collected the spatiotemporal gait data using an automated system .  Descriptive statistics were calculated for each variable measured at each walking condition . The data were then compared to those from the Swedish study . The results indicate several significant differences between Kuwaiti and Swedish subjects in their manner of walking . These results suggest a need to include data from subjects with diverse cultural background s when a data base on normal gait is developed or a need to limit the results of the data base to a specified ethnic population 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 Exercise plays a pivotal role in maximizing peak bone mass in adulthood and maintaining it through aging , by imposing mechanical loading on the bone that can trigger bone mineralization and growth . The optimal type and intensity of exercise that best enhances bone strength remains , however , poorly characterized , partly because the exact peak loading of the bone produced by the diverse types of exercises is not known . By means of integrated motion capture as an input to dynamic simulations , contact forces acting on the hip of 20 young healthy adults were calculated during walking and running at different speeds . During walking , hip contact forces ( HCFs ) have a two-peak profile whereby the first peak increases from 4.22 body weight ( BW ) to 5.41 BW and the second from 4.37 BW to 5.74 BW , by increasing speed from 3 to 6 km/h . During running , there is only one peak HCF that increases from 7.49 BW to 10.01 BW , by increasing speed from 6 to 12 km/h . Speed related profiles of peak HCFs and ground reaction forces ( GRFs ) reveal a different progression of the two peaks during walking . Speed has a stronger impact on peak HCFs rather than on peak GRFs during walking and running , suggesting an increasing influence of muscle activity on peak HCF with increased speed . Moreover , results show that the first peak of HCF during walking can be predicted best by hip adduction moment , and the second peak of HCF by hip extension moment . During running , peak HCF can be best predicted by hip adduction moment . The present study contributes hereby to a better underst and ing of musculoskeletal loading during walking and running in a wide range of speeds , offering valuable information to clinicians and scientists exploring bone loading as a possible nonpharmacological osteogenic stimulus . © 2015 American Society for Bone and Mineral Research BACKGROUND Few studies have addressed trunk and pelvis movements during gait , although they play an important role in gait control . The aim of this study was to compare trunk and pelvis kinematics between slower walking ( 1 , 2 , 3 , 4kmph ) and normal walking ( 5kmph ) , and between healthy adults who were young ( n=15 , 20 - 30years ) and older ( n=17 , 50 - 60years ) . METHODS After 4min of treadmill walking ,  the 3-dimensional trunk and pelvis kinematics was measured ( Polhemus Liberty ™ , 250Hz ) . A repeated measures ANOVA with simple contrasts was used to look for differences between the velocity conditions of walking and independent t-testing for comparison between the age groups ( significance level : 5 % , SPSS20 ) . FINDINGS Walking more slowly than with normal velocity induces ( 1 ) a decrease in vertical center of mass of the trunk displacement , trunk lateral flexion and axial rotation and pelvis lateral and antero-posterior tilting , and ( 2 ) an increase in lateral and antero-posterior center of mass of the trunk displacement . Compared to young persons , older persons show : ( 1 ) larger pelvis axial rotations and trunk lateral and antero-posterior movements , and ( 2 ) smaller pelvis lateral tilting and trunk vertical movements and rotations . INTERPRETATION The literature reports that patients often walk slowly and that older persons show different gait patterns compared to young persons . This study shows that there are changes in trunk and pelvis kinematics ( 1 ) when walking more slowly than with normal velocity and ( 2 ) in older persons compared to young persons . These data could be taken into account in gait rehabilitation Background Identifying risk factors for knee pain and anterior cruciate ligament ( ACL ) injury can be an important step in the injury prevention cycle . Objective We evaluated two unique prospect i ve cohorts with similar population s and method ologies to compare the incidence rates and risk factors associated with patellofemoral pain ( PFP ) and ACL injury . Methods The ‘ PFP cohort ’ consisted of 240 middle and high school female athletes . They were evaluated by a physician and underwent anthropometric assessment , strength testing and three-dimensional l and ing biomechanical analyses prior to their basketball season . 145 of these athletes met inclusion for surveillance of incident ( new ) PFP by certified athletic trainers during their competitive season . The ‘ ACL cohort ’ included 205 high school female volleyball , soccer and basketball athletes who underwent the same anthropometric , strength and biomechanical assessment prior to their competitive season and were subsequently followed up for incidence of ACL injury . A one-way analysis of variance was used to evaluate potential group ( incident PFP vs ACL injured ) differences in anthropometrics , strength and l and ing biomechanics . Knee abduction moment ( KAM ) cut-scores that provided the maximal sensitivity and specificity for prediction of PFP or ACL injury risk were also compared between the cohorts . Results KAM during l and ing above 15.4 Nm was associated with a 6.8 % risk to develop PFP compared to a 2.9 % risk if below the PFP risk threshold in our sample . Likewise , a KAM above 25.3 Nm was associated with a 6.8 % risk for subsequent ACL injury compared to a 0.4 % risk if below the established ACL risk threshold . The ACL-injured athletes initiated l and ing with a greater knee abduction angle and a reduced hamstrings-to-quadriceps strength ratio relative to the incident PFP group . Also , when comparing across cohorts , the athletes who suffered ACL injury also had lower hamstring/quadriceps ratio than the players in the PFP sample ( p<0.05 ) . Conclusions In adolescent girls aged 13.3 years , > 15 Nm of knee abduction load during l and ing is associated with greater likelihood of developing PFP . Also , in girls aged 16.1 years who l and with > 25 Nm of knee abduction load during l and ing are at increased risk for both PFP and ACL injury 
    Output:
    
Conclusions This review identified that speed affected the gait patterns of different population s with respect to the amplitude of spatiotemporal parameters , joint kinematics , joint kinetics , and ground reaction forces .
Specifically , most of the values analyzed decreased at slower speeds and increased at faster speeds .