1. POSTECH H uman S ystem D esign Lab oratory Stair ascent and descent at different inclinations Robert Riener et al. (2002, Italy and Germany) Gait and Posture 2009. 7. 28. Tue. Heo, Jiyoon

2. POSTECH H uman S ystem D esign Lab oratory Contents 1. Introduction 2. Methods 3. Results 4. Discussion 2

3. POSTECH H uman S ystem D esign Lab oratory 1. Introduction  Objectives  To face the question of how staircase inclination affects the kinematic and kinetic patterns of stair climbing  To ascertain if ascent and descent patterns are to be considered as particular evolution of the level walking pattern.  Expected effects  Adding to our understanding of the diverse and complicated process involved in human locomotion  Designing of private and public environments where stairs are employed  Using in the field of gait rehabilitation 3

4. POSTECH H uman S ystem D esign Lab oratory 1. Introduction  Literature survey  To investigate normal human stair ascent and descent “a study of lower-limb mechanics during stair climbing” (Andriacchi et al., 1980), etc.  To investigate focused on joint moments “Aduction–adduction moments at the knee during stair ascent and descent.” (Kowalk et al., 1996)  To investigate focused on joint powers “Six degree of freedom joint power in stair climbing” (Duncan et al., 1997)  To investigate focused on plantar pressure characteristics “Plantar pressure characteristics during stair climbing and descent” (Wervey et al., 1997)  To investigate focused on reproducibility “Reproducibility of the kinematics and kinetics of the lower extremity during normal stair-climbing” (Yu B et al., 1997)  To investigate stair climbing of patients with knee and hip implants “The influence of total knee-replacement design on walking and stair climbing” (Andriacchi et al., 1982), etc.  No comprehensive analysis is available in the literature that discusses biomechanics of stair ascent and descent at different inclinations 4

5. POSTECH H uman S ystem D esign Lab oratory  Instrumented staircase design  Composed of 4 steps and a platform at the upper end  Adjustable in height 24˚: 13.8 X 31.0 cm (riser X tread) 30˚: 17.0 X 29.0 cm 42˚: 22.5 X 25.0 cm  The lower 3 steps were instrumented with six strain-gauge force transducers each  Camera-based movement analyser (ELITE, BTS Milan, Italy)  Measurements  GRF  The vertical component of the GRM  Joint angles  Cycle time 2. Methods 5

6. POSTECH H uman S ystem D esign Lab oratory  Subjects  10 healthy males Height: 1.79 ± 0.05 m Weight: 82.2 ± 8.5 kg Age: 28.8 ± 2.9 years  Free of any musculo-skeletal or neurological dysfunction  Protocols  The subject walked barefoot at normal, comfortable speed.  Prior to data acquisition, the subjects accustomed to the stair motion.  The subjects did 5 repetitive trials at each conditions.  Ascent stride cycle: foot contact on 2 nd step ~ 4 th step  Descent stride cycle: foot contact on 3 rd step ~ 1 st step  Foot contact always occurred with the same foot 2. Methods 6

7. POSTECH H uman S ystem D esign Lab oratory  Data of level walking  From 26 healthy male subjects (similar) were taken out of the data bank of the Centro di Bioingegneria gait laboratory. Height: 1.80 ± 0.06 m Weight: 76.7 ± 9.4 kg Age: 27.2 ± 2.6 years  Data processing  Hip and knee angle: computed in sagittal projection.  Ankle joint angle: computed in plane (dorsiflextion / plantarflexion)  Angular velocities and accelerations: first and second derivatives of the joint angle data  Anthropometric parameters: estimated by regression equations (Zatsiorksky and Seluyanov, 1983)  Segment lengths: directly measured  Mechanical power at each joint: the product of joint moment and angular velocity 2. Methods 7

8. POSTECH H uman S ystem D esign Lab oratory  Gait cycle parameters  Ascent: stance duration increased only slightly with stair inclinations  Descent: stance duration percentage progressively decreased with increasing inclinations  Stride cycle duration: ascent (1.43 s) > descent (1.20 s) 3. Results 8

9. POSTECH H uman S ystem D esign Lab oratory  Kinematics – foot placement  ‘-’ sign means that the subject contacted the step with forefoot.  Ascent: independent from inclination  Descent: distinctly related with inclination 3. Results 9

10. POSTECH H uman S ystem D esign Lab oratory  Kinematics – joint angles 3. Results 10 AscentDescent Foot contact (0% cycle time) Hip: flexed Knee: flexed Ankle: dorsiflexed Hip: slightly flexed Knee: almost extended Ankle: plantarflexed Subsequent phase Hip/Knee: extended Ankle: plantarflexed Hip/Knee: flexed Ankle: dorsiflexed  plantarflexed RangesMaximum flexion angles increased with increasing inclination Compared w/ level walking Clearly distinguished (ex; Angular ranges) ※ gray column in graph means toe-off phase

11. POSTECH H uman S ystem D esign Lab oratory  Ground reaction forces 3. Results 11 AscentDescent Produced forces Relatively smallRelatively large Influence of inclination Relatively small (sig. dependency was only in the vertical component during early descent stance. Increased 14.8%) Compared w/ level walking Preserved most of the features

12. POSTECH H uman S ystem D esign Lab oratory  Joint moments 3. Results 12 AscentDescent Moments in stance phase Hip: extension moments Knee: (2 nd half) decreased Hip: flexion moments Knee: (2 nd half) increased Influence of inclination Not sig. dependency - during swing phase - first half stance phase of knee joint Sig. dependency - max. moment: hip (ascent), knee, ankle(early phase) Compared w/ level walking Different ※ gray column in graph means toe-off phase

13. POSTECH H uman S ystem D esign Lab oratory  Joint powers 3. Results 13 AscentDescent PowerProducing energy during most phase (+)Predominantly, energy was absorbed (-) Influence of inclination More dependent on staircase inclination than joint angles and moments Compared w/ level walking Some similarities (ex; ankle late stance, hip early stance) Some differences: Knee (3.8 times difference during descent) ※ gray column in graph means toe-off phase

14. POSTECH H uman S ystem D esign Lab oratory  Differences between ascent and descent  Fundamental consideration (McFadyen and Winter, 1988) The ascending task consists primarily of a transfer of muscle energy into potential energy of the body During descent, the potential energy has to be dissipated (absorbed) by the muscle  consequence: During loading response phase (pull up): forces in descent > forces in ascent During phase of energy production (push up): forces in descent < forces in ascent ※ if we consider that 50% of the ipsilateral stride cycle corresponds to the initial contact of the contralateral side : push up at ankle joint  pull up at knee and hip joints ※ Note that during these phases, the antigravity muscles perform eccentric contractions (they generate force while they are lengthened).  Be a potential risk of muscle fiber damage 4. Discussion 14

15. POSTECH H uman S ystem D esign Lab oratory  Influence of staircase inclination  Significant dependency of most gait parameters on staircase inclination Angular ranges of all joints, Joint power patterns (Muller et al., 1998), GRF  But the intensity of this dependency was different Only little influence on gait phase parameters(tab 1.), and joint moment patterns(fig 4.) 4. Discussion 15

16. POSTECH H uman S ystem D esign Lab oratory  Comparison with level walking  One can assume that ascending and descending motions are to be considered as particular evolution of level walking.  Only little signs could be found that indicate an adaptation or shift in the motor patterns when moving from level to stair walking - vertical GRF, some joint powers (partly at hip and knee)  The typical sharing of energy absorption among the leg joints was not observed during level walking  The gait patterns did not change in a progressive way. In most cases, the intersection of the extrapolated linear regression with the vertical line at 0˚ inclination clearly deviated from the characteristic values observed at level walking. The subjects contacted the steps with forefoot during climbing. 4. Discussion 16