Lecture 1: Protective Equipment Flashcards
What factors prevent athletic injuries?
- Design
- to prevent injury
- to prevent injured parts from further injury - Proper fit
- Proper selection
Characteristics of protective equipment
- simple to fit and maintain
- durable and reliable
- not extremely expensive
- minimal functional interference
4 Principles of Protective Equipment
Deflection
Dissipation
Deformation
Absorption
Deflection
turning aside/off course
Properties that help deflect force from the body
- hard
- rounded
- smooth
- ridges
ex. helmets
Dissipation
Disperses focal force over a LARGER SURFACE
- layers are needed
- various materials (different densities) –> dissipate force especially over bony prominences
ex. shoulder pads (spread force to protect AC jt.)
Deformation
Change in shape or structure
- Cantilever shoulder pads –> deforms and force goes to belts
May blow apart at high force
- bike helmet –> ability to deform reduces after major collision
Absorption
Receives force without recoil
Materials: felt, foam (open + closed cell), air, fluid
Increased density = more resistance @ HIGH force (protection)
Decreased density = more absorption @ LOWER force (comfort –> avoid irritation)
Felt
- less likely to shift or move over skin
- absorbs fluids (sweat, blood) –> heavy when wet
- not very resilient (stays compressed once compressed)
Open Cell Foam
- like sponge
- low-resilience: does NOT bounce back
- used to pad bony prominences (elbows, shin, inside helmet)
- used to protect skin under hard edges of protective equipment
decreased density = more absorption @ LOWER force
Closed Cell Foam
used primarily for PROTECTION
high resilience –> material rebounds and returns to original shape quickly
- offers less cushioning at low levels of impact
- not as comfortable close to skin
ex. football helmet
increased density = more resistance @ HIGHER force
What makes equipment fit?
- molds to body part
- allows function
- allows for quick removal in emergencies
Fitting Helmets
- wet hair
- 1-2 finger widths above eyebrow
- covers occiput and entire skull
- mask should be 2-3 finger width from nose (good vision)
- strap snug to chin (2 vs 4 point)
What can alter fit of a helmet?
Temperature
Hair length
Deterioration of internal padding
Loss of air
Shoulder Pads Fitting
inner padding covers shoulders (over AC jt.) and cups deltoid
- hockey has longer padding below delts
neck unrestrictive
Modifying equipment
- modifications should be ONLY according to manufacturer’s specifications and should not alter fit
- modifications should not increase stress or damage (NO drilling, cutting, slicing)
How to determine what equipment is best for a sport?
Think about
- biomechanics of body part
- outer surface “shell”
- inner surface “liner”
- method of attachment (strap, belt, ties)
- sport-specific design
- position-specific modifications
- what are you trying to protect against? ppl? projectiles?
Equipment protecting against people
Protecting agaisnt high mass/low velocity
- hard, smooth outer shell w/ absorbing inner liners
Equipment protecting against projectiles
Protecting against low mass/high velocity
ex. puck, baseball
Football helmets
Protects against players - high mass/low velocity
- hard, smooth outer shell w/ inner liners (air/closed cell)
- different masks based on position
- 2 or 4 point strap
Straps on helmet
Limit forward/backward tilting
Football shoulder pads
Protect shoulders and limit force to acromion
- Shell of hard, smooth plastic (deflection)
- Layers of soft padding under shell (dissipation, deformation, absorption)
Hockey helmet
protects against ppl and pucks (high velocity/low mass + low velocity/high mass)
- hard shell w/ high density (protection) inner layer
- open (comfort) + closed cell (protect) foam combo
- full cage or 1/2 visor
Goalie mask
protects against puck (high velocity/low mass)
- hard shell w/ ridges (deflection)
- open and closed cell foam combo (absorption)
Hockey shoulder pads
- overlapping cup to protect clavicle and deltoid (dissipation)
- chest portion usually felt/nylon/foam (absorption)
Neck protectors
Purpose is to PREVENT THROAT LACERATIONS
- usually soft cloth w/ Kevlar
- minimal padding against low mass/high velocity projectiles
Shin pads
Molded plastic to cover knees and shins (deflection/deformation)
Some articulation around knee (allows more freedom)
layered nylon/foam or felt lining (absorption)
Baseball helmet
protects against low mass/high velocity (pitch)
- hard round plastic (deflection)
- protects from focal impact (dissipate and absorbs force)
Baseball chest protector
- Soft foam
- heart guard – extra layers
Baseball catcher’s mask
- protection from ball and bat splinters
Conventional
- poor vision and jaw padding
- minimal ridges
- all force goes to chin or forehead –> does NOT bounce off
Hockey style
- better vision and protection (deflection)
- problems: hot, heavy, hard to flip off
Lacrosse helmet
high velocity/low mass and low velocity/high mass
- sits off crown of head
- mask farther from face = increased visibility
- visor peak for sun
Lacrosse equipment
Shoulder pads
- similar to hockey = less AC protection
- increased arm range for stick work
Arm pads: protect length of arm from slash
Gloves: open palm
- wrist padding for greater movement = higher injury risk
Bike/Skating Helmet
- outer designed for one massive impact at high velocity (deformation)
- foam inner lining (absorption/comfort)
- peaked front and back to protect face and occiput
Bike/Skating other equipment
Wrist guards
- rigid plastic over open cell foam
- deflects impact of FOOSH (fall out on outstretched hand) –> absorption
Knee/elbow pads
- soft open cell foam covered by hard plastic
External Last
Shape
- form on which the shoe is constructed
Straight-lasted shoe vs curve-lasted shoe
Curved last
for ppl w/ higher rigid arch
- neutral –> STABILITY
- medial deviation of forefoot
- hollowed-out medial longitudinal arch
Straight last
for ppl w/ flat feet or ppl who turn in too far too fast
- stability –> MOTION CONTROL
- solid plantar surface
- extended midsole in medial longitudinal arch
- increased base of support
Internal last
Construction
interface btwn foot and midsole
- can be board (more stable), slip (two halves sewn –> less stable) or a combination (less stable)
Slip lasting
- solid line of stitching down middle of shoe
- increased flexibility
- neutral or shoes that need flexibility
- if foot does not absorb shock well
ex. soccer, climbing
Board lasting
- solid board stitched to upper of shoe
- increased torsional resistance to pronation (SUPPORT)
- better for orthotics
- for ppl with very flat feet (very mobile) –> need stability
Upper of shoe
- all components above midsole
- nylon, mesh, leather, synthetics
- contains midfoot control technologies
- confoms to bony abnormalities
Midsole
- between upper and outsole
- shock absorption vs motion control
- densities depend on sport and foot type
- shoes that need better feel/ball control might not have a midsole (ex. soccer)
made of polyurethane, EVA or compressed EVA
Polyurethane
Midsole material - PU (Skor bar)
- controls heavier runners
- MOTION CONTROL (stops foot rolling in)
- dense –> Skor bar
EVA
Midsole material (Aero bar)
- lighter
- when compressed, it has higher durability
- SHOCK ABSORPTION
- Aero chocolate bar (bubbles, light)
Midsole shape
Tapered from heel to toe
Thickest part under heel
Outsole
- Protective layer on bottom
- Protection, durability, flexibility, traction
- Use of different rubbers and materials specific to sport
Heel Counter
- stiff material at back of shoe to resist ankle motion
- more pronation needs stiffer heel counter
- at the top of heel counter is ankle collar to protects/cushion ankle and Achilles
- if too wide, fill with felt or heel cup (better than having it too tight in forefoot)
Footwear Fit
- fit larger foot on weight-bearing foot at the END of day
- length should not be increased to accommodate width (will cause hyperextension)
- to test width, place full weight on shoe. Push thimbs together over top of shoe and should produce RIPPLE
- heel should be soft enough to absorb energy but not collapse under gait
- shape of shoes (last) is straight, curved or semi-curved
– rigid (cavus) foot needs curved last w/ cushioning - mobile (flat) foot needs straight last
Fitting Heel to forefoot height
- important w/ rigid cavus foot or forefoot pain
- too high heel = more force on forefoot
- lower heel = energy can be taken throughout foot
look for show w/ only a slight difference in height
Neutral foot/high arch
Neutral cushioning (need Aero bar)
- single density
- thermoplastic heel counter
- mild torsional rigidity
- EVA (proprietary cushioning)
- slip and curve lasted
- used for “normal”, neutral asymptomatic population
Mild Over-pronators
Stability shoes (need Skor bar)
- thermoplastic heel counter
- double density midsole
- PU
- moderate/extreme torsional rigidity
- midfoot control (motion control)
- curved last and board lasted
Severe over-pronators/Flat Feet
Motion control shoe
- thermoplastic heel counter
- triple density midsole (LOTS of PU)
- medial and laterally posted
- extreme torsional rigidity
- midfoot control (motion control)
- straight lasted and board lasted
