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The effect of shoe hardness and treadmill stiffness on rearfoot kinematics during running
Abstracts-International
Society of Biomechanics XIV Congress 1993
675
THE EFFECT OF SHOE HARDNESS AND TREADMILL STIFFNESS ON REARFOOT KINEMATICS DURING RUNNING Steven T. McCaw', Joseph Hamill', Barry T. Bates' and Tim Derrick' 'Dept of HPERD, Illinois State University, Normal, USA; 'Dept of Exercise Science, University of Massachusetts, Amherst, USA; 'Dept of Exercise & Movement Science, University of Oregon, Eugene, USA. of differing stiffnesses, the interactive effect Although shoes are worn on terrains of shoe midsole hardness and running surface stiffness has not been investigated. The purpose of the study was to describe the effect on selected rearfoot motion variables of running on surfaces of different stiffnesses in shoes having different midsole constructions. Two pairs of shoes were constructed for the study, identical except for midsole durometer (hard shoe: 70; soft shoe: 45, on a shore A scale). Four healthy males ran (speed = 2.91 m-d) on a motorized treadmill with surface settings adjustable to hard medium (127 kN/m) or soft (100 kN/m) stiffness. Ten trials of right-leg (198 W/m), rearfoot motion were recorded using 200 Hz video. Magnitude and temporal variables were analyzed with repeated measures ANOVA (a=.05). Results indicated no significant interaction between shoe hardness and treadmill stiffness. A main effect of shoe hardness was identified for maximum rearfoot angle and time to maximum rearfoot angular velocity, with significant differences between all treadmill settings. On average, runners exhibited 6.67O more aversion and reached maximum rearfoot velocity 0.02s later in the support phase when wearing soft shoes. A main effect of treadmill hardness was identified for maximum rearfoot velocity, but only the soft and hard treadmill settings with hard shoes were significantly different. The results indicate that rearfoot motion parameters are not affected by an interaction between running shoe midsole hardness and running surface stiffness, and suggest that midsole hardness is a greater determinant of rearfoot motion during the stance phase than is running surface compliance. Supported in part by an ACSM Visiting Scholar Award to S.T. McCaw.
THE RELATIONSHIP BETWEEN FRONTAL SURFACE AREA AND ANTHROPOMETRIC PARAMETERS IN RACING CYCLISTS B.D. McLean Australian Institute of Sport, Canberra,Australia Wind resistanceis the primary resistanceto motion faced by the cyclist. The cyclist's projected frontal surface area (FSA) is one of the factors influencing wind resistanceduring cycling. A relationship betweena cyclist’s anthropometry and their FSA has not been established.The purpose of this study was to determinethe relationship between anthropometricparametersand FSA in racing cyclists. FSA was determined for thirty nine experiencedmale cyclists sitting on their own bicycles with hands in the handlebar ‘drops’, right crank horizontally forward and with the head up. The angle of trunk inclination, measuredas a line betweenthe greater trochanter and the first thoracic vertebraeranged between 32” and 39” to the horizontal. Anthropometric measurestaken were height, mass,acromial height, tibia1 height, chest, waist, arm, thigh and calf girth, as well as biacromial and biiliac crest width. Correlation analysis was conducted to determine the relationship betweenanthropometricparametersand FSA. The anthropometricparameters which best pfedicted FSA were mass and height. FSA(m ) = .00215 M(kg) + .18964 Ht(m) - .07961 (r=.90) Other combinations of anthropometricparametersdid not improve the prediction of FSA. The inclusion of trunk angle pith massand height did improve the predicition of FSA. FSA(m ) = .00217 M(kg) + .18437 Ht(m) + .00397 T,#deg) - .21215 (r=.92) Log _ Log analysis showed that FSA is a function of mass . Since large cyclists have greater masswith which to perform work, larger cyclists can be seento have ;!n aerodynamicadvantageover smaller cyclists.
AERODYNAPIC CHARqCTERISTICS PF CYCLE2WHEELS AF RACING CYCLISTS B.D. McLean , R. Danaher , L. Thompson , A. Forbes and G. Coca Australian Institute of Sport, Canberra,Australia *AerospaceEngineering, Royal Melbourne Institute of Technology, Melbourne, Australia This study investigatedthe aerodynamicdrag characteristicsof cycle wheels and the time trial positions of racing cyclists. All tests were done in a 3m by 3.6m wind tunnel. Wheel testing was performed on isolated wheels. Five wheels were tested: 1. a “conventional wheel” with 36 round spokes;2. a wheel with an aerodynamicrim and 36 flat bladed spokes;3. a conventional wheel with lycra wheel covering; 4. a flat disc wheel;5 a trispoked wheel. The wheels were testedin a set of bicycle forks which could be yawed to simulate crosswinds.The wheels were rotated consistentwith the wind velocity. The influence of different wheels on performancein a IOOOmtime trial was assessedby mathematically modelling the cyclists equation of motion and inputting the wheel drag determinedfrom the wind tunnel tests.Wind tunnel testing of the cycle and rider was conducted on four elite male cyclists to establishthe optimum riding positions and the effect of other incidental changes.All bikes had ‘triathlon’ handlebarsand the handlebaranglesto the horizontal were varied to establish the lowest drag setting for each rider. The results showed that disc and trispoke wheels had the lowest wheel drag, followed in order by the covered wheel, the bladed spoke wheel and the conventional wheel. Estimated 1OOOm time showed that in a no wind condition the disc wheel was superior, whereasin a crosswind condition the trispoke was superior. Results of the cyclists position testing showed that in general lowest drag was obtained when the forearms were between 5” and 20” to the horizontal. Other measurementsestablishedthe drag was lower when; the arms were progressively moved in towards the centreline; water bottles were carried on the seattube rather than the down tube. An optimum head position also exists for minimum helmet drag. Different helmets have different optimum head positions.
Society of Biomechanics XIV Congress 1993
675
THE EFFECT OF SHOE HARDNESS AND TREADMILL STIFFNESS ON REARFOOT KINEMATICS DURING RUNNING Steven T. McCaw', Joseph Hamill', Barry T. Bates' and Tim Derrick' 'Dept of HPERD, Illinois State University, Normal, USA; 'Dept of Exercise Science, University of Massachusetts, Amherst, USA; 'Dept of Exercise & Movement Science, University of Oregon, Eugene, USA. of differing stiffnesses, the interactive effect Although shoes are worn on terrains of shoe midsole hardness and running surface stiffness has not been investigated. The purpose of the study was to describe the effect on selected rearfoot motion variables of running on surfaces of different stiffnesses in shoes having different midsole constructions. Two pairs of shoes were constructed for the study, identical except for midsole durometer (hard shoe: 70; soft shoe: 45, on a shore A scale). Four healthy males ran (speed = 2.91 m-d) on a motorized treadmill with surface settings adjustable to hard medium (127 kN/m) or soft (100 kN/m) stiffness. Ten trials of right-leg (198 W/m), rearfoot motion were recorded using 200 Hz video. Magnitude and temporal variables were analyzed with repeated measures ANOVA (a=.05). Results indicated no significant interaction between shoe hardness and treadmill stiffness. A main effect of shoe hardness was identified for maximum rearfoot angle and time to maximum rearfoot angular velocity, with significant differences between all treadmill settings. On average, runners exhibited 6.67O more aversion and reached maximum rearfoot velocity 0.02s later in the support phase when wearing soft shoes. A main effect of treadmill hardness was identified for maximum rearfoot velocity, but only the soft and hard treadmill settings with hard shoes were significantly different. The results indicate that rearfoot motion parameters are not affected by an interaction between running shoe midsole hardness and running surface stiffness, and suggest that midsole hardness is a greater determinant of rearfoot motion during the stance phase than is running surface compliance. Supported in part by an ACSM Visiting Scholar Award to S.T. McCaw.
THE RELATIONSHIP BETWEEN FRONTAL SURFACE AREA AND ANTHROPOMETRIC PARAMETERS IN RACING CYCLISTS B.D. McLean Australian Institute of Sport, Canberra,Australia Wind resistanceis the primary resistanceto motion faced by the cyclist. The cyclist's projected frontal surface area (FSA) is one of the factors influencing wind resistanceduring cycling. A relationship betweena cyclist’s anthropometry and their FSA has not been established.The purpose of this study was to determinethe relationship between anthropometricparametersand FSA in racing cyclists. FSA was determined for thirty nine experiencedmale cyclists sitting on their own bicycles with hands in the handlebar ‘drops’, right crank horizontally forward and with the head up. The angle of trunk inclination, measuredas a line betweenthe greater trochanter and the first thoracic vertebraeranged between 32” and 39” to the horizontal. Anthropometric measurestaken were height, mass,acromial height, tibia1 height, chest, waist, arm, thigh and calf girth, as well as biacromial and biiliac crest width. Correlation analysis was conducted to determine the relationship betweenanthropometricparametersand FSA. The anthropometricparameters which best pfedicted FSA were mass and height. FSA(m ) = .00215 M(kg) + .18964 Ht(m) - .07961 (r=.90) Other combinations of anthropometricparametersdid not improve the prediction of FSA. The inclusion of trunk angle pith massand height did improve the predicition of FSA. FSA(m ) = .00217 M(kg) + .18437 Ht(m) + .00397 T,#deg) - .21215 (r=.92) Log _ Log analysis showed that FSA is a function of mass . Since large cyclists have greater masswith which to perform work, larger cyclists can be seento have ;!n aerodynamicadvantageover smaller cyclists.
AERODYNAPIC CHARqCTERISTICS PF CYCLE2WHEELS AF RACING CYCLISTS B.D. McLean , R. Danaher , L. Thompson , A. Forbes and G. Coca Australian Institute of Sport, Canberra,Australia *AerospaceEngineering, Royal Melbourne Institute of Technology, Melbourne, Australia This study investigatedthe aerodynamicdrag characteristicsof cycle wheels and the time trial positions of racing cyclists. All tests were done in a 3m by 3.6m wind tunnel. Wheel testing was performed on isolated wheels. Five wheels were tested: 1. a “conventional wheel” with 36 round spokes;2. a wheel with an aerodynamicrim and 36 flat bladed spokes;3. a conventional wheel with lycra wheel covering; 4. a flat disc wheel;5 a trispoked wheel. The wheels were testedin a set of bicycle forks which could be yawed to simulate crosswinds.The wheels were rotated consistentwith the wind velocity. The influence of different wheels on performancein a IOOOmtime trial was assessedby mathematically modelling the cyclists equation of motion and inputting the wheel drag determinedfrom the wind tunnel tests.Wind tunnel testing of the cycle and rider was conducted on four elite male cyclists to establishthe optimum riding positions and the effect of other incidental changes.All bikes had ‘triathlon’ handlebarsand the handlebaranglesto the horizontal were varied to establish the lowest drag setting for each rider. The results showed that disc and trispoke wheels had the lowest wheel drag, followed in order by the covered wheel, the bladed spoke wheel and the conventional wheel. Estimated 1OOOm time showed that in a no wind condition the disc wheel was superior, whereasin a crosswind condition the trispoke was superior. Results of the cyclists position testing showed that in general lowest drag was obtained when the forearms were between 5” and 20” to the horizontal. Other measurementsestablishedthe drag was lower when; the arms were progressively moved in towards the centreline; water bottles were carried on the seattube rather than the down tube. An optimum head position also exists for minimum helmet drag. Different helmets have different optimum head positions.