Transcript Sport Biomechanics - Academics | Kansas State University

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Exercise Biomechanics Reading
Assignment
Textbooks:
– Kreighbaum pp 233-241, Chapter 8 (spinal exercises and resistive
exercise equipment)
Hamill pp 202-207, 216-222 (conditioning, stresses, and injury
potential of lower extremity)
• Journal article summaries by students
– Porcari, J.P., et al (2005) The effects of neuromuscular electrical stimulation
training on abdominal strength, endurance, and selected anthropometric
measures. Journal of Sport Science & Medicine, 4:66-75.
(http://www.jssm.org/vol4/n1/9/v4n1-9pdf.pdf)
– Porcari, J.P., et al (2000) Exercise response to elliptical trainers. Fitness
Management. August, 1-3.
(http://www.precor.com/pdf/articles/exercise_response.pdf)
– Hinterman and Nigg(1998) Pronation in runners: Implications for injuries.
Sports Medicine. 26:169-176.
– O’Conner and Hamill (2002) Does running on a cambered road predispose a
runner to injury? Journal of Applied Biomechanics, 18:3-14.
Exercise Biomechanics Outline
• Selected major areas of endeavor in exercise biomechanics
• Evaluating exercise equipment
• Biomechanics of resistive exercises & equipment
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Strength-position curves
Use of cams in exercise equipment
Pelvic girdle balance and abdominal exercises
Back extension exercises
Posture and lifting guidelines
Knee joint structure and loading
Rearfoot movement and related issues
Designing shoes to prevent injury
Review of selected journal and review articles on ex biom
Biomechanical correlates of exercise –
areas of interest, endeavor, & contribution
• Design and analysis of fitness programs
• Design of fitness exercises
– Which exercises are most effective in meeting program ogjectives?
– Which exercises are potentially, or inherently unsafe and to be
either avoided or used with caution?
– 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 abdominal ex equip)
– aerobic equipment
• Relative merits of different exercise modes (e.g., stairclimber, bicycle,
treadmill, rowing machine, elliptical exerciser)
• Running shoes
Methods of Evaluation of Ex Equip
• Source: (Jung, A.P. The evaluation of home exercise equipment
claims. ACSM’s Health and Fitness Journal. 4(5): 14-16,30-31.
• Check physiological and biomechanical principles and ACSM
standards.
• Review research, if available
– Critically review research – Are appropriate methods used? Who sponsored it?
Where was research reported?
• Ask professors or other experts (Barstow, Harms, Gyurcsik,
Estabrooks, Ferguson)
• Review product reviews in fitness magazines (Club Industry, Athletic
Business, Fitness Management)
• Try it yourself.
• Interview professionals who have supervised its use.
• Design and conduct your own research.
• Note: guidelines for selection are on Federal Trade Commission
Website (http://www.ftc.gov)
Criteria for evaluating aerobic exercises
• Degree of overload on cardiorespiratory system
• Relevance to fundamental movements and activities of daily
living
• Proportion of total body musculature involved
• Degree of compressive stress on femoral head and lumbar
vertebral bodies (sites of most osteoporotic fractures)
• Compressive stress on patella and knee joint
• Range of motion and torque at hip, knee, and lumbar spine
• Motivational features (comfort, user friendly, feedback,
RPE)
• Likelihood of continued usage
• Cost
• Other?
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
Lumbar spinal shear force is directly
related to pelvic girdle position
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:
Lifting quidelines:
(1)bend knees
(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
Knee Ligaments and cartilage
Knee loading summary
• Forces at tibiofemoral Joint
– Shear stress is greater during open kinetic chain exercises
such as knee extensions and knee flexions
– Compressive stress is greater during closed kinetic chain
exercises such as squats and weight bearing exercises.
• Forces at Patellofemoral Joint
– With a squat, reaction force is 7.6 times BW on this joint.
– Increases as knee is flexed
Movement of subtalar joint
Foot Pronation and Tibial Torsion:
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:
Designing shoes to prevent injury
(Sport Research Review,Nike, inc.)
• “The primary function of an athletic shoe cushioning
system is to reduce the potentially injurious effects of
repeated impacts between the foot and the ground”
Shoe design and injury, cont’d
Aerobic Dance Injuries (Sport
Research Review,Nike, inc.)
• Most injuries are to instructors and involve
the shin and foot
Football shoes (Sport Research
Review, Nike, inc.)
• Change from seven ¾” cleats to
fourteen ¾” cleats reduced knee
injuries 50% and serious knee
injuries 75-80%
• Stiff insert has dramatically
reduced turf toe (sprain of the
plantar capsule ligament
complex of the first
metatarsophalangeal joint
(MPJ))
Sensory evaluation of shoes
• Purpose: assess product attributes and preferences
• Three main categories of sensory evaluation methods
– Discrimination testing (use trained panels)
• Is product A noticeably different from product B?
– Descriptive testing (use trained panels)
• What key sensory attributes characterize Products A,B,C?
– Affective testing (trained panels or reps of target consumers)
• What level of liking does product A generate on one or more sensory
attributes?
• Which product is preferred on the basis of these attributes?
Sensory evaluation applied to
traditional forms of product testing
(Sport Research Review, Nike, inc.)
• Dynamic testing
– Short-term, performance-based of functionality and
likeability
– One to four samples at a time
• Fit trials
– Short-term
– Mimic point-of-service
purchase experience
• Long-term wear testing