Overview of gait, posture and activities of daily living biomechanics which gives a simplified explanation and perspective to study the human motion

1. Biomechanics of Integrated
Function- Gait, Posture & ADL
-Soniya Lohana
Ist MPT
Department of Sports Physiotherapy

2. Biomechanics
of
Gait

3. Contents
 Introduction
 Phases of Gait Cycle
 Kinematics of Gait
 Kinetics of Gait
 Temporal & Spatial Variations of Gait Cycle
 Muscle Activity during Gait
 Determinants of Gait
 Evidences
 References

4. What is Human Locomotion/Gait ?
• Translatory progression of body as a whole
• Produced by co-ordinated, rotatory movements of
body segments
• Series of rhythmic, alternating movements of the
trunk & limbs which result in forward progression of
the Center of Gravity.

5. Initial contact of one leg to initial contact of the
same leg.

7. Phases of Gait Cycle
0 % 12 % 50 % 62 % 100 %

8. WHY KINETICS & KINEMATICS IS IMPORTANT?
• Kinetic analysis makes it possible to measure the magnitude
and direction of external forces acting on limb, during the
different phases of gait
• Kinematic analysis makes it possible to determine the
locomotion of joint in space
• The combination of above 2 methods makes it feasible the
calculation of the externally generated moments of force
at various joints

9. Kinematics of Gait
Spatial Characteristics Temporal Characteristics
 Step Length
Stride Length
Step Width
Angle of Progression
 Velocity
Step Duration
Cadence

11. Sagittal Plane Motion
• In the sagittal plane, the two vertical oscillations of the
body’s COM follow a smooth sinusoidal curve.
• The curve’s highest point occurs at midstance for each
foot while the lowest segment of the sinusoidal curve is at
double support.
• Actual vertical displacement of the COM varies from 2 to
5 cm, depending on stride length and walking speed.
• Angular motions of flexion and extension occur at the
hip, knee, and ankle in the sagittal plane.

13. Frontal Plane Motion
• Maximum lateral displacement occurs during unilateral stance
and is about 2 cm to the left and to the right.
• When visualized in both the sagittal and frontal planes during
walking, the body’s COM is at its highest in the sagittal plane
and its most lateral position in the frontal plane at the same
time

15. Transverse Plane
Motion

16. • Pelvis: 5° to 8° lateral tilt in the frontal plane, 3°
anterior and posterior tilt in the sagittal plane, and a
total of 8° protraction and retraction in the transverse
plane.
• Hip: 10° extension to 25°–30° flexion in the sagittal
plane; 15° adduction to 5° abduction in the frontal
plane; and 8° to 14° in the transverse plane.
• Knee: full extension to 60° flexion in the sagittal
plane; 3° to 8° in the frontal plane; 10° to 20° in the
transverse plane
•Ankle and foot: 10° dorsiflexion to 20°
plantarflexion
in the sagittal plane; 5°–8° inversion and eversion.

17. Kinetics of Gait
- Newton’s 3rd law of motion
• Ground reaction force (GRF)
- force transmitted from floor to the foot , passed on up to all
body segments
- reflection of body weight and acceleration
- vertical , anterior – posterior, and mediolateral
Relationship of GRF & jt.axis during stance phase

19. Kinetics of Gait
THE FORCES OF MAJOR IMPORTANCE IN ANALYSIS OF
HUMAN LOCOMOTION ARE:
Internal Forces-The forces exerted by muscular contraction
Muscle forces & Passive tension from connective tissues
External forces – The forces exerted by the pull of gravity
Inertia, Gravity & Friction

23. Muscles of Gait
1. PRETIBIAL GROUP
• During the heel strike phase, lengthening
contraction(eccentric ) of the foot dorsiflexors lets the
foot down from heel strike to foot flat position in a
slow and controlled manner. In rest of stance phase,
the invertors and evertors act to keep the foot stable
in ML direction.
• Important for the stability on rough ground or on a
walking on a hillside.

24. 2.CALF GROUP- GASTRONEMIUS AND SOLEUS
Max activity during the push off phase to propel the COG
up and forward
3. QUADRICEPS GROUP-
Max activity after heel strike , acting as shock
absorbers to control knee flexion to 15 degrees.
4. HAMSTRINGS GROUP-
Double peak of activity just before and after heel strike.
first peak occurs during swing , and it keep the knee from
buckling. second peak at the termination of stance phase
working toward hip and knee extension for push off.

25. 5. ABDUCTOR GROUP- GLUTEUS MEDIUS AND
MAXIMUS
- Active during heel strike and early stance phase to stabilize
the pelvic tilt to 5 degrees.
6. ADDUCTOR GROUP-
- after heel strike, they assist abductors to stabilize the pelvis
- At end of stance phase, they work together with other hip
flexors to accelerate the limb forward in preparation for
swing

26. 7. GLUTEUS MAXIMUS-
- more active during heel strike phase, when it acts as a
shock absorber. Their extension function keep both hip and
knee from buckling.
8. ERECTOR SPINAE-
Becomes active during heel strike and its activity is
necessary to keep the trunk from folding forward from the
force of inertia and gravity. Also stabilises the trunk
mediolaterally.

29. Determinants of Gait
• Used to minimize excursion of CG in vertical &
horizontal planes
• Reduces the energy consumption of
ambulation
Pelvic Rotation
Lateral pelvis tilt
Knee flexion
Ankle Mechanism
Foot Mechanism
Physiological valgus of knee

30. 1. Pelvic rotation:
• Forward rotation of the pelvis in the
horizontal plane approx 8 degree on the swing-
phase side
• Reduces the angle of hip flexion & extension
• Enables a slightly longer step-length w/o
further lowering of COG

31. 2. Pelvic tilt:
- 5 degree dip of the swinging side (i.e. hip
adduction)
- In standing, if this dip is a positive Trendelenberg sign
- Reduces the height of the apex of the curve of COG

32. 3. Knee flexion in stance phase:
- Approx. 20 degree dip
- Shortens the leg in the middle of stance phase
- Reduces the height of the apex of the curve of COG

33. 4. Ankle mechanism:
-Lengthens the leg at heel contact
-Smoothens the curve of COG
-Reduces the lowering of COG

34. 5. Foot mechanism:
- Lengthens the leg at toe-off as ankle moves
from dorsiflexion to plantarflexion
- Smoothens the curve of COG
- Reduces the lowering of COG

35. 6. Physiological valgus of knee
- Reduces the base of support, so only little lateral
motion of pelvis is necessary.

36. Common Gait Abnormalities
• Antalgic Gait
- Gait pattern in which stance phase on affected side is
shortened
- Corresponding increase in stance on unaffected side
- Common causes:
OA, Fracture,
Tendinitis

37. • Lateral Trunk bending/Trendelenberg gait
-Usually unilateral
-Bilateral = waddling gait
• Common causes:
 Painful hip
 Hip abductor weakness
 Leg-length discrepancy
 Abnormal hip joint

38. HIP ABDUCTOR LOAD & HIP JOINT REACTION
FORCES

39. • Functional Leg-Length Discrepancy
- Swing leg: longer than stance leg
- 4 common compensations:
A. Circumduction
B. Hip hiking
C. Steppage
D. Vaulting

40. Increased Walking Base
- Normal walking base: 5-10 cm
• Common causes:
- Deformities
- Abducted hip
- Valgus knee
• Instability
- Cerebellar ataxia
- Proprioception deficits

41. Inadequate Dorsiflexion Control/foot drop gait
- In stance phase (Heel contact – Foot flat):
Foot slap
- In swing phase (mid-swing): Toe drag
• Causes:
 Weak Tibialis Ant.
 Spastic plantarflexors

42. Running Gait
- Require greater balance, muscle strength,
ROM than normal walking.
- Difference b/w running and walking
• Reduced BOS
• Absence of double support
• More coordination and strength needed
• Muscle must generate higher energy to raise HAT higher than
in normal walking.
• Divided into flight and support phase

43. Stair Gait
Ascending and descending stairs is a
basic body movement required for ADL
Stair gait involves stance and swing phase
SWING PHASE(36%)
• Foot clearance
• Foot placement
STANCE PHASE(64%)
• Weight acceptance
• Pull up
• Forward continuance

44. SIMILARITIES & DIFFERENCES BETWEEN
LEVEL GROUND GAIT AND STAIR GATE
Similarities to Walking Differences with Walking
•Double support periods
•Ground reaction forces have double peak
•Cadence similar
•Support moment is similar (always
positive with two peaks)
•More hip and knee flexion
•Greater ROM needed
•Peak forces slightly higher
•CoP is concentrated under
metatarsals, rarely near heel
•Step height may vary from stairway to
stairway
•Railings may be present

45. • Title - Gait-training devices in the treatment of lower extremity injuries in sports
medicine: current status and future prospects
Authors- Alexandra F. DeJong & Jay Hertel
• Aim- This review seeks to provide synthesized information on gait-training techniques and
devices applied, in four of the most prevalent chronic lower extremity injuries seen in sports
medicine.
• Methods- Comprehensive searches were performed identify gait-training articles in Chronic
Ankle Instability (CAI), Exercise-Related Lower Leg Pain (ERLLP), Patellofemoral Pain
(PFP), and Anterior Cruciate Ligament with Reconstruction (ACLR) populations. reviewed
articles and extracted data includes study demographics, gait-training techniques, devices
used, and primary gait-training outcomes. 58 articles were included in this review Pooled
analyses were performed for common outcomes within each injury category. Current
evidence supports destabilization training and pressure medialization tactics for CAI (n = 9),
footstrike/loading and cadence interventions for ERLLP (n = 11) and PFP (n = 7), and limb
off-loading techniques for ACLR (n = 4). Commonly used devices included accelerometers
(n = 6), custom gait-training footwear (n = 9), metronomes (n = 14), and pressure sensors
(n = 5).
• Conclusion-Wearable sensors will continue to revolutionize gait-training and allow for
ecologically valid gait-training interventions.

46. • Title- Gait Mechanics and Tibiofemoral Loading in Men of the ACL-
SPORTS- RCT
Author- Jacob J. Capin et al
• Aim- Development of the anterior cruciate ligament specialized post-operative
return-to-sports (ACL-SPORTS) program, to test the effect of 10 post-operative
training sessions consisting of strength, agility, plyometric, and secondary
prevention exercises (SAPP) or SAPP plus perturbation (SAPPþPERT) training
on gait mechanics after ACLR.
• Methods- A total of 40 male athletes (age 237 years) after primary ACLR were
randomized to SAPP or SAPPþPERT training and tested at three distinct, post-
operative time points: 1) after impairment resolution (Pre-training); 2) following
10 training sessions (Post-training); and 3) 2 years after ACLR. Knee kinematic
and kinetic variables as well as muscle and joint contact forces were calculated
via inverse dynamics and a validated EMG-informed musculoskeletal model.
• Conclusion- There were no significant changes seen however, meaningful gait
asymmetries mostly resolved between post-training and 2 years after ACLR
regardless of intervention group.

47. • Title- Gait Mechanics and Second ACL Rupture: Implications for
Delaying Return-to-Sport
Author- Jacob J. Capin et al.
• Aim- to compare gait biomechanics and return-to-sport time frames in a
matched cohort of young female athletes who, after primary ACLR, returned
to sport without re-injury or sustained a second ACL injury.
• Methods- 14 young women involved in jumping, cutting, and pivoting sports
underwent motion analysis testing after physical therapy and impairment
resolution. Following objective return-to-sport clearance, 7 athletes sustained
a second ACL rupture within 20 months of surgery. They matched them by
age, sex, and sport-level to seven athletes who returned to sports without re-
injury. Data were analyzed using a previously validated, EMG-informed,
patient-specific musculoskeletal model.
• Conclusion- Delayed return-to-sport clearance even in the absence of gait or
clinical impairments following primary ACL reconstruction may be necessary
to mitigate second ACL injury risk in young women.

48. BIOMECHANICS OF POSTURE

49. Contents
 Introduction
 Bipedal & Quadripedal Stance
 Kinetics & Kinematics of Posture
 Sagittal Plane Alignment
 Frontal Plane Alignment
 Posterior View
 Deviations from Optimal Alignment of Normal Posture
 Evidences
 References

50. What is Posture?
• Alignment of Body Segments
• Attitude assumed by the body either with
support during muscular inactivity or by
means of the coordinated action of many
muscles working to maintain stability.
• Postural adjustments are rapid & automatic in
normal function.
• Requires interaction of multiple systems.
• Static Vs Dynamic

51. ERECT BIPEDAL STANCE AND
QUADRUPEDAL POSTURE
• Erect bipedal stance gives us
freedom for the U.E
• certain disadvantages -
increases the work of the
heart; places increased stress
on the vertebral column,
pelvis, and lower extremities;
and reduces stability.
• Small base of support and
large center of gravity
- In quadrupedal posture the
body weight is distributed
between the upper and
lower extremities.
- Large base of support and low
center of gravity

52. Kinetics & Kinematics of Posture
 External forces: Inertia, Gravity and Ground
Reaction Forces(GRF’s)
Internal forces: muscle activity, passive
tension in ligaments, tendons, joint capsules and
other soft tissue structures

53. Inertia
• In the erect standing posture the body
undergoes a constant swaying motion called
postural sway or sway envelope
• Sway envelope for a normal individual, standing with
4” between the feet –
12° in sagittal plane and 16° in frontal plane
Gravity
• Gravitational forces act downward from the body’s
COG
• In static erect standing posture, the LOG must fall
within the BOS

54. Ground Reaction Forces Vector
• GRFV is equal in magnitude but opposite in direction to
the gravitational force in erect standing posture
• The point of application of GRFV is at the body’s centre
of pressure(COP)
• COP is located in the foot in unilateral stance and b/w
the feet in bilateral standing postures

55. Analysis of Posture
- In normal standing posture, the LOG falls close to, but
not through most joint axes
- Compressive forces are distributed over the weight
bearing surfaces of joints; no excessive tension
exerted on ligaments
- Skilled observational analysis of posture involves
identification of the location of body segments
relative to the LOG
- Body segments-either side of LOG are symmetrical
- A plumb line is used to represent the LOG

57. SAGITTAL PLANE
ALIGNMENT
IN NORMAL POSTURE
In erect standing, the body is aligned
approximately so that a line
through the body’s COM passes
very close to the ear, slightly
anterior to the acromion process
of the scapula, close to the greater
trochanter, slightly anterior to the
knee joint, and anterior to the
ankle joint

64. Deviations from Optimal Alignment in
Sagittal Plane
• Foot & Toes: Claw Toe & Hammer Toe
• Knee- Flexed Knee Posture, Genu Recurvatum
• Pelvis- Anterior Pelvic Tilt
• Spine- Kyphosis, Lordosis
• Head- Forward Head Posture

68. FRONTAL AND
TRANSVERSE PLANE
ALIGNMENT

69. POSTERIOR ASPECT

70. Deviations from Optimal Alignment in
Anterior- Posterior View
• Foot & Toes: Pes Planus, Pes Cavus, Hallux
Valgus
• Knee- Genu Varum, Genu Valgum, Squintting
or cross-eye patella, Grasshopper eyes patella
• Spine- Scoliosis

74. SCOLIOSIS

76. • Title-Biomechanical simulation of different postures obtained from
three sport branches
Author- Farkas Andrei Zoltan et al.
• Aim- To run a biomechanical simulation with the AnyBody modeling
system using anthropometric and postural data obtained from
professional athletes of three different sport branches and highlight
the muscle activity differences that occur between the mean
posture of each sport’s specific somatotype.
• Methods- Postural measurements were performed on three sport
batches from different branches of sports (Basketball, Volleyball,
Football) All the athletes performed a series of non-invasive testing
using a multi-sensor modular baropodometer (force plate) and the
Zebris CMS-HS spine examination system.The analysis was repeated
several times and the same result came up every time.
• Conclusion- Postural deviations that occur due practicing different
sports are significant. After modeling/simulation with the AnyBody
modeling system, the influence of posture on muscle activity
throughout the body is highlighted.

77. • Title-Does the type of sport practised influence foot posture and knee
angle? Differences between footballers and swimmers
Author- Eva Lopezosa-Reca et al.
• Aim-To observe the differences in foot posture and the angle of the knee
according to different physical activities.
• Methods- 78 football players and 72 swimmers were recruited,
and in each case a foot posture analysis, based on the foot posture 10
index (FPI), was conducted and the Q angle of the knee was determined.
The following mean values were obtained for the
lower extremities: in the swimmers, FPI 6.45 ± 2.04 and Q angle
15.38º ± 3.79º. In the footballers, FPI 2.23 ± 1.72 and Q angle
13.16º ± 1.36º.
• Conclusion- There were statistically significant differences 15
(p < 0.001) between the two groups. The swimmers presented a
foot posture with a tendency towards pronation, and a Q angle
with a tendency towards valgus, while the results for the footballers
were within the normal range

78. BIOMECHANICS
OF
ACTIVITIES
of
DAILY
LIVING

79. Contents
 Introduction
 Common ADL’s
 Sequence of Movement in Various ADL’s
 Joint Motion in Various ADL’s
 Muscle Activity in Various ADL’s
 Evidences
 References

80. BIOMECHANICS
• The study of mechanics in the human body is
referred to as biomechanics.
• Functional Biomechanics: link between
human body and environment which dictates
human function.
• Human functions are 3 dimensional.

81. WHAT ARE ADL’S ?
• Activities of Daily Living are simple as well as
complex movements which humans carry out
everyday
• Activities involved in taking care of themselves,
performing work related tasks, enjoying leisure and
recreational time.
• To analyze the biomechanics:
Sequence of Movement
Joint Motion
Muscle Activity

82. MOBILITY- SIT TO STAND
Sequence of movement-
Trunk moves upright to place COM over feet & hands move to rest
COM moves forward over the feet as L.L extend
Hands are on arms of the chair
Hips move to edge of the seat and body leans forward to place trunk’s
COM over legs
Extremities are prepared to accept body weight

83. Joint Motion
Hips are moved forward in the chair – B.W moves from one side of pelvis to other
as the NWB pelvis rotates forward until hips are on the edge
Trunk moves to an upright position when hips are on the edge of the seat- in
preparation elbow flexed at 90 degree at the arm rest
Shoulders are hyperextended with elbows behind the trunk, hips flexed as trunk
forward over thighs
Knees flexed beyond 90 degree to move feet under the hips and ankles are
dorsiflexed
Forearm either pronated or neutral midposition, Wrist extension, Fingers &
thumb flexed
Movement to standing- shoulders- hyperextension to neutral hyperextension,
elbows extend, wrist-neutral
Neck from hyperextension to align with trunk in neutral as hips and knees extend
Head moves ahead of feet so that COM-positioned over feet
B.W fully accepted by L.E and the individual stands

84. Muscle Activity
Trunk muscles ( Erector
Spinae) contract
isometrically to stabilize the
trunk
Quadratus Lumborum & G.
Medius & Minimus on the
elevated hip lift& rotate
pelvis forward as
contralateral side
elongated
Abdominal muscles( R.Ab,
Int. & Ext. Obliques) then
flex to move trunk to an
erect position
Hamstrings contract to
increase knee flexion so
that feet slide under chair,
Gastrocnemius assist knee
flexion & contracts to
stabilize feet, Ankles D.F by
T.ant
Post. Deltoid, Lat. D, Teres
Major move shoulder into
extension as downward
scapula rotators
(Rhomboids & L. scapulae)
position the scapulae
Once Buttock lifts, Hips
extend via co-contraction of
G.max and Hamstrings
Knee Extends by
Quadriceps co-contraction
and Gastrocnemius and the
individual stands

85. LIFTING
• There are various types of lifting positions.
a. With lumbar flexion =Stoop lift: extensor of back
contribute to most of the work. (Lumbo-pelvic
rhythm)
b. With neutral position of lumbar= Squat lift:
extensor of hip contribute to most of the work.
(Reverse Lumbo-pelvic rhythm)
• The load on lumbar region increases as inclination of
trunk increases.

86. Sequence of movement-
Box moved closer to the body, Trunk erect, Standing motion takes place
U.E moved forward in shoulder flexion with extended elbows to reach and
obtain a firm grasp
Hips flex to move torso over the box, Back Straight & Neutral
Ankle Dorsiflexed, Tibia over foot, Knees flexed to lower the body. So hands
able to grasp the box
To move in squat, hips laterally rotate to about 45 degree and flex to 90
degree
Wide BOS, Stand close to the object
Flexion of spine, proper alignment using hips to move torso rather the back
Head & Trunk – in midline alignment stabilize the Lumbar spine

87. Positioning of Head, Trunk & Pelvis
Scapular Rotators co-contract to stabilize scapulae as shoulders move to about 60 degree
flexion, adducted near trunk with shoulders midway between medial and lateral rotation
Elbow, Forearm extension and mid position to reach the box and grasp
Wrist Extended into functional position. Thumb and fingers move first into full extension and
abduction- reach and then flexion and adduction to grasp
Box Lifted moved closer to the trunk, Hip and Knee move from flexion to extension to
maintain BOS with hip in extension, slight abduction and knee in extension
Joint Motion

88. Postural control- neck flexors
(SCM and scalenes) and
extensors (spleneii).
The erector spinae and
abdominals contract to
stabilize the trunk.
The wide BOS in hip abduction
is accomplished by
contractions of the gluteus
medius and minimus,TFL, and
the sartorius.
Moving into a squat, the
erector spinae muscles
isometrically contract to
maintain proper spinal
position and the abdominals
provide lumbar stabilization.
hips and knees flex using
eccentric contractions of the
gluteus maximus and
hamstrings at the hip and
quadriceps at the knee.
As the squat deepens, the
deep lateral rotators, gluteus
maximus, and sartorius
continue to maintain the hips
in lateral rotation.
The gastrocnemiussoleus
muscles stabilize the ankles in
this closed chain position on
the floor.

89. As the box is lifted, the shoulders
move into flexion by the clavicular
portion of pectoralis major, anterior
deltoid, and coracobrachialis,
and adducted alongside the trunk
by the pectoralis major, latissimus
dorsi, and teres major, midway
between medial and lateral rotation
by the subscapularis, anterior
deltoid, infraspinatus, and teres
minor muscles.
The elbows are maintained in
extension by cocontraction the
triceps and elbow flexors (biceps
brachii, brachialis, and
brachioradialis).
The wrists are stabilized in
functional position by cocontraction
of wrist extensors (extensor carpi
radialis longus and brevis and
extensor carpi ulnaris) and finger
flexors (flexor digitorum
superficialis and profundus);
fingers are also adducted by the
palmar interossei.
When the individual is ready to lift
the box, the knees and hips extend
through concentric contraction of
the gluteus maximus and
hamstrings at the hip and
quadriceps at the knee.
The BOS stays wide in hip
abduction; lateral rotation is
provided by the gluteus medius,
gluteus minimus, sartorius,gluteus
maximus, and deep lateral rotators
to stand up holding the box.

90. Biomechanics of Oral Hygiene & Feeding

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93. THANK-YOU !