Transcript Sport Biomechanics - Kansas State University

Biomechanical correlates of exercise –
areas of interest, endeavor, & contribution
• Design/analysis of fitness programs
• Design of fitness exercises
– are exercises inherently safe and effective?
• Exercises to avoid (e.g., deep knee bends, good morning exercise)
– movements, forces, injury potential
• Analysis of fitness exercises
– are exercises being executed properly?
• Design, selection, and analysis of fitness equipment
– resistive equipment (e.g., thesis on situp ex equip)
– aerobic equipment
• Relative merits of exercise mode
• Running shoes
Biomechanical aspects of aerobic exercise
Adrian, p. 219
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Potential for injury increases with body weight
Airborne activities produce greater forces than non-airborne activities
Fast twisting movements of arm and upper trunk produce lower back reaction forces
Stress is inversely proportional to body surface area exposed
Joint shear stress is minimal if bones are aligned in a straight line
Knee joint stress is minimized it knee is alighted above the foot
Alignment of trunk above pelvis minimizes unbalanced stress of spine
Keep limbs close to trunk for maximum equilibrium
Longer limbs involve greater MOI, thus they are harder to move and accelerate
Joint reaction force increases with speed of angular movement
The taller person needs more time to perform an activity
Safety can be increased or decreased by modifying the intensity of the exercise
Biomechanics of Resistive exercises
• Factors affecting force
application
– Force-velocity relationship
– Strength-joint position
relationship (combination of
angle of pull and force/length
relationship)
• Should we provide the same
degree of overload
throughout the movement? If
so, how do we do it?
Use of Cams in Ex Equipment:
Pelvic Girdle Balance
Compression and shear forces:
Spinal Flexion
Exercises
• Effect of
– Anchoring feet?
– Bending knees?
– Placement of hands and
arms?
– Inclined board?
Back Extension Exercises to Avoid:
Good morning exercise:
Hyperextended back:
Recommended Extension Exercise
Effect of speed on effects of exercise:
Torque = Wd + MOI x ang acc
Effect of posture on
lumbar compression
force:
Torque while lifting:
Recommendations: (1)bend knees
and (2)keep weight close to hips
Knee Joint
Structure:
25% of Alpine skiing
injuries are ligament
injuries
Peripatellar pain
(runner’s knee)
caused by imbalance
of stress on patella
Lower Extremity
Misalignment:
Q angle is larger in females due to
Wider hip structure, increasing
potential for PFPS (Patellofemoral
pain syndrome)
Quadriceps Tendon
and Patella Force
Lines
Compressive force at PFJ is ½ body
wt during normal walking, and over
3 times bw during stair climbing
Comp force increases as knee flexion
Angle increases
Structure and tissues of shank
and foot:
Subtalar axis:
Foot Pronation and Tibial Torsion:
Plantar Fascium:
Plantar fascitis is 4th most
common cause of pain
among runners
(1st – knee pain, 2nd – shin
splints, 3rd- achilles tendonitis)
Arches
of the
Foot:
GRF while
Running
Force vectors on
different parts of
foot
Rearfoot Movement During
Running:
Types of running injuries
Example of Double Density
Midsole:
Effects of Rearfoot Double
Density Midsole
on rearfoot
position:
Effects of Rearfoot & Forefoot Double
Density Midsole on takeoff angle: