Chapter 3Chapter 3

AnthropometryAnthropometry

AnthropometryAnthropometry

• Deals with the measure of Deals with the measure of size, mass, shape and size, mass, shape and inertial properties of the inertial properties of the human body segments. human body segments.

Biomechanical ModelsBiomechanical Models

• Facilitates prediction of a body’s Facilitates prediction of a body’s response and the design of the response and the design of the workspace interfaceworkspace interface• PhysicalPhysical

• crash test dummies crash test dummies

Biomechanical ModelsBiomechanical Models

• Facilitates prediction of a body’s Facilitates prediction of a body’s response and the design of the response and the design of the workspace interfaceworkspace interface• PhysicalPhysical

• crash test dummies crash test dummies

• MathematicalMathematical• Joint moment of forceJoint moment of force

Biomechanical ModelsBiomechanical Models

• Facilitates prediction of a body’s Facilitates prediction of a body’s response and the design of the response and the design of the workspace interfaceworkspace interface• PhysicalPhysical

• crash test dummies crash test dummies

• MathematicalMathematical• Joint moment of forceJoint moment of force

Biomechanical ModelsBiomechanical Models

• Facilitates prediction of a body’s Facilitates prediction of a body’s response and the design of the response and the design of the workspace interfaceworkspace interface• PhysicalPhysical

• crash test dummies crash test dummies

• MathematicalMathematical• Joint moment of forceJoint moment of force

Biomechanical ModelsBiomechanical Models

• Facilitates prediction of a body’s Facilitates prediction of a body’s response and the response and the design of the design of the workspace interfaceworkspace interface• PhysicalPhysical

• crash test dummies crash test dummies

• MathematicalMathematical• Joint moment of forceJoint moment of force

Measurement of Body-Segment Measurement of Body-Segment Physical PropertiesPhysical Properties

• Segments defined by bony prominence Segments defined by bony prominence (landmarks) (landmarks) (fig 3.2)(fig 3.2)

• Human body: system of Human body: system of rigid linksrigid links• known physical size and form known physical size and form • connected at identifiable jointsconnected at identifiable joints

Caveat: Body-segment linksCaveat: Body-segment links

• No joint in the human body is a simple No joint in the human body is a simple single-axis hinge joints, but are single-axis hinge joints, but are considered considered so in many analysesso in many analyses (1 Degree of Freedom) (1 Degree of Freedom)

• AssumeAssume

• segments are segments are rigid links rigid links

• joints are joints are frictionless and hingedfrictionless and hinged

Body-segment linksBody-segment links

• Link lengths can be Link lengths can be defined as the defined as the distance between distance between projected centersprojected centers• Resulting error in Resulting error in

link length estimate link length estimate is < is < ++ 5% 5%

Body-segment linksBody-segment links

• Acceptable degree of model Acceptable degree of model simplification reflect analysis goal: simplification reflect analysis goal: • Assumptions valid for most analysesAssumptions valid for most analyses• Crash test dummies require consideration Crash test dummies require consideration

of joint structure, ligaments, muscle of joint structure, ligaments, muscle response, organs, etc. response, organs, etc.

• Injury risk (Lives!!) depends on the Injury risk (Lives!!) depends on the validity of the modelvalidity of the model

Average Average Segment Segment

Lengths as Lengths as Proportion of Proportion of

Total Body Total Body Height (TBH)Height (TBH)

[see Table 3.7][see Table 3.7]

Padding goalie stats no longer an option: NHL catalogues netminders' measurementsPadding goalie stats no longer an option: NHL catalogues netminders' measurements  By DAVE STUBBS, © Copyright (c) The Montreal Gazette, November 17, 2009By DAVE STUBBS, © Copyright (c) The Montreal Gazette, November 17, 2009

   Habs' Carey Price is slated to have his measurements taken next month for new equipment rules that will come into effect next season.Kay Whitmore would make a pretty fair tailor or building contractor. For now, he's the National Hockey League's go-to guy with a tape measure.Whitmore, the league's manager of hockey operations, is gradually working his way through NHL dressing rooms to catalogue the legs of 60-plus netminders. When fully collected, his data will be applied to a formula providing new size-specific pad-length rules for the 2010-11 season.Next fall, a few goalies might be wearing pads taller than the current 38-inch NHL maximum. The pads of others might be a little shorter; some should see no change at all.It's part of the league's effort, in concert with the players' association, to streamline goaltenders - to maintain or improve their protection while putting them on a sheet of ice that's level for all."We're working with the union, dealing with fairness and the safety of the goalies, and trying not to upset equipment manufacturers," Whitmore said with a laugh.The plan, approved last week by NHL general managers, asks: Why should a 6-foot-5 goalie like Nashville's Pekka Rinne look rink-length to, say, the Canadiens' Jaroslav Halak, who is six inches shorter, but wearing pads of precisely the same size? While the NHL is satisfied that goalies are wearing sleeker upper-body protection - they're no longer the human spinnakers who billowed to fill the net - the issue of pad size was less easily solved.Body measurement of goalies was done last March by each team's equipment staff. But their leg measurements were sometimes wildly inconsistent. So Whitmore, a former NHL netminder, is now taking his own tape measure to goalies' legs. He's the one who inspects equipment before its first NHL use to ensure its legality and does postgame spot-checks to make certain things have not been tweaked beyond the rules.The leg measurement is two-fold: it's taken from the floor, beneath a goalie's bare foot, up to the centre of his kneecap, the knee slightly bent; and from the knee to the pelvic bone.Whitmore also is charting arm length, circumference of chest, waist and hips, and skate-boot size, as well as determining whether a goalie needs a pant-size allowance depending on how he wears his chest and torso protection. Applied to a complex formula, the leg data will give a goalie the maximum length next season for his pad, which remains the current 11 inches wide. The aim is to have it reach roughly mid-thigh, no longer above the crotch to almost navel-height.But protection, Whitmore said, remains paramount. "If a guy is 6-foot-5 with really short legs (and thus would be wearing shorter pads), he'll have a longer upper-body pad to cover his longer torso," Whitmore said. "We can't ask guys not to play their style because some of the newer equipment created that style."Whitmore, based in Toronto, figures he's scoped about 30 goalies so far. He expects to size up the Canadiens' Carey Price and Halak on Dec. 26, when the Habs are at the Air Canada Centre to play the Maple Leafs. He tries to measure all goalies, shoulders to toes, before a game-day morning skate when the netminder is in undergarments and of normal bulk, neither waterlogged nor dehydrated."The goalies are willing to do their part to help everyone, as long as it's fair for all," Whitmore said. That's not to say goaltenders still won't try to bend the rules, even if there's little that would surprise a fraternity brother. Whitmore has heard stories about netminders asking their pant suppliers to replace an XXL tag with an L, in a bid to detour the size police.Whitmore, who can spot that ploy a mile away, expects to keep a close eye on resized goalies who might exercise a little, well, creativity to reclaim a lost half-inch. But this plan isn't about shrinking the player; if a larger body needs longer leg coverage, he'll get it.Vaughn Sports, which makes equipment for Price and about 30 NHL and AHL goaltenders, expects to have NHL/NHLPA-approved sizes in time to make pads for pro customers to use in summer hockey."Goaltending is totally different than it was 20 years ago," said Jorg Achenbach, Vaughn's pro-services representative. "I believe goalies of today are much better athletes, mentally tougher and superior in conditioning. "They understand the physics, dynamics and laws of averages of the position. They also have fantastic goalie coaches who are students of the game."Indeed, much has changed since the days of harness-maker Emil (Pop) Kenesky, who from the mid-1920s almost until his death in 1974 sketched blueprints for his NHL customers and hand-stitched their horsehide- and felt-stuffed leather pads on his Hamilton, Ont., workbench. Computers and synthetic materials are the production staples today, with a pair weighing less than just one of Kenesky's. For now, at least, streamlining goalies has silenced talk of larger nets, a sacrilege discussed during the lockout."Maybe that's still out there in the sense that, 'Hey, if the (equipment) doesn't work, we always have larger nets,' " Whitmore said. "I don't know if there's a lot of appetite for that. I've learned to never say never, but this game is probably in the best place it's ever been."Given the choice of more net to protect or one less inch of pad to guard the status quo, goalies would agree that Whitmore's tape measure is the lesser of two evils. By far.

Padding goalie stats no longer an option: NHL catalogues netminders' measurementsPadding goalie stats no longer an option: NHL catalogues netminders' measurements  By DAVE STUBBS, © Copyright (c) The Montreal Gazette, November 17, 2009By DAVE STUBBS, © Copyright (c) The Montreal Gazette, November 17, 2009

  When fully collected, his data will be applied to a formula providing new size-specific pad-length rules for the 2010-11 season.Next fall, a few goalies might be wearing pads taller than the current 38-inch NHL maximum. The pads of others might be a little shorter; some should see no change at all.It's part of the league's effort, in concert with the players' association, to streamline goaltenders - to maintain or improve their protection while putting them on a sheet of ice that's level for all."We're working with the union, dealing with fairness and the safety of the goalies, and trying not to upset equipment manufacturers," Whitmore said with a laugh.The plan, approved last week by NHL general managers, asks: Why should a 6-foot-5 goalie like Nashville's Pekka Rinne look rink-length to, say, the Canadiens' Jaroslav Halak, who is six inches shorter, but wearing pads of precisely the same size? While the NHL is satisfied that goalies are wearing sleeker upper-body protection - they're no longer the human spinnakers who billowed to fill the net - the issue of pad size was less easily solved.Body measurement of goalies was done last March by each team's equipment staff. But their leg measurements were sometimes wildly inconsistent. So Whitmore, a former NHL netminder, is now taking his own tape measure to goalies' legs. He's the one who inspects equipment before its first NHL use to ensure its legality and does postgame spot-checks to make certain things have not been tweaked beyond the rules.The leg measurement is two-fold: it's taken from the floor, beneath a goalie's bare foot, up to the centre of his kneecap, the knee slightly bent; and from the knee to the pelvic bone. Whitmore also is charting arm length, circumference of chest, waist and hips, and skate-boot size, as well as determining whether a goalie needs a pant-size allowance depending on how he wears his chest and torso protection. Applied to a complex formula, the leg data will give a goalie the maximum length next season for his pad, which remains the current 11 inches wide. The aim is to have it reach roughly mid-thigh, no longer above the crotch to almost navel-height.But protection, Whitmore said, remains paramount. "If a guy is 6-foot-5 with really short legs (and thus would be wearing shorter pads), he'll have a longer upper-body pad to cover his longer torso," Whitmore said. "We can't ask guys not to play their style because some of the newer equipment created that style.”

Body-segment mass and weightBody-segment mass and weight

• TheThe massmass of the body segments of the body segments adds additional stresses to the body adds additional stresses to the body beyond those exerted by external beyond those exerted by external forces (forces (resistance to accelerationresistance to acceleration))

• These These weightweight related stresses can related stresses can be of considerable magnitude in be of considerable magnitude in certain postures (certain postures (a forcea force))

InertiaInertia

Resistance of an object to Resistance of an object to changing its current state of changing its current state of

motion. motion.

Body-segment Body-segment inertialinertial properties properties

When a segment can translate When a segment can translate and/or rotate during activity, the and/or rotate during activity, the

inertial properties inertial properties of the segment of the segment must be considered in the must be considered in the

analysisanalysis

Two inertial properties to considerTwo inertial properties to consider

• Mass: resistance to linear accelerationMass: resistance to linear acceleration

• Moment of Inertia: resistance to angular Moment of Inertia: resistance to angular accelerationacceleration

ConversionsConversions

• Mass (kg) to Weight (lbs) Mass (kg) to Weight (lbs) multiply by 2.2 (downward)multiply by 2.2 (downward)

• Mass (kg) to Weight (N): Mass (kg) to Weight (N): multiply by 9.81 (downward)multiply by 9.81 (downward)

• Weight (lbs) to Weight (N): Weight (lbs) to Weight (N): multiply by 4.45multiply by 4.45

Body-segment mass and weight:Body-segment mass and weight:

• Body segment mass (weight) Body segment mass (weight) can be expressed as a can be expressed as a proportion of whole-body mass proportion of whole-body mass (weight) without great loss of (weight) without great loss of accuracyaccuracy• TBM: total body massTBM: total body mass

• Many sources exist (see p41 in text)Many sources exist (see p41 in text)

Table 3.4, p41Table 3.4, p41

Recommended Values for Percentage Recommended Values for Percentage distribution of total body weightdistribution of total body weight

Grouped segments, % of total body wtGrouped segments, % of total body wt

Head and neckHead and neck 8.4%8.4%

TorsoTorso 50%50%

Total armTotal arm 5.1%5.1%

Total legTotal leg 15.7%15.7%

data from Winter (1989) data from Winter (1989) based on Dempster (1956) data (overhead)based on Dempster (1956) data (overhead)

Percent distribution of total body massPercent distribution of total body massGrouped segmentsGrouped segments % of total body wt% of total body wtHead and neckHead and neck 8 % 8 %HATHAT 68 %68 %Total armTotal arm 5 %5 %Total legTotal leg 16 %16 %

One of the most common sources for anthropometric data.

Winter tableWinter table

Winter table (cont’d)Winter table (cont’d)

Example Example

• TBM of individual is 82 kg (180 lbs) TBM of individual is 82 kg (180 lbs) • 82 kg x -9.81 = 804 Newtons82 kg x -9.81 = 804 Newtons

• What is mass of upper body? What is mass of upper body? • from Winter table: HAT (head-arms-trunk) = from Winter table: HAT (head-arms-trunk) =

67.8% of TBM67.8% of TBM

• Calculate: (82 kg) x (0.678) = Calculate: (82 kg) x (0.678) = 55.6 kg55.6 kg• 180 lbs x 0.678 = 122 lbs180 lbs x 0.678 = 122 lbs

• 804 N x 0.678 = 545 Newtons804 N x 0.678 = 545 Newtons

Body segmentBody segmentcenter of mass locationcenter of mass location

• Insufficient to know only the mass (weight) Insufficient to know only the mass (weight) of a body segment to perform an analysisof a body segment to perform an analysis

• Must locate the Must locate the center of mass center of mass for each for each segment (and the entire body)segment (and the entire body)• single point masssingle point mass• point of application of the gravitational forcepoint of application of the gravitational force• See Table 3.5 p43, Table 3.13 p.48See Table 3.5 p43, Table 3.13 p.48• Better: off Winter overheadBetter: off Winter overhead

Winter tableWinter table

ExampleExample

• Total Arm of individual is 51 cm (20 Total Arm of individual is 51 cm (20 inches) longinches) long• 0.51 m long0.51 m long

• Locate Center of massLocate Center of mass• from Winter table: 0.53 (53% of arm length from Winter table: 0.53 (53% of arm length

from the from the proximalproximal end) end)

• Calculate: (0.51 m) x (0.53) = Calculate: (0.51 m) x (0.53) = 0.27 m from 0.27 m from the proximal end of armthe proximal end of arm

ImportanceImportance

• Knowledge ofKnowledge of• mass center location in segmentmass center location in segment• % TBM (weight) % TBM (weight) • link lengthlink length

• sufficient input for static analysis to sufficient input for static analysis to calculate forces and moments at each calculate forces and moments at each joint for a given body posture.joint for a given body posture.

Draw a FBD of Arm Draw a FBD of Arm (60 inches, 215 pound person)(60 inches, 215 pound person)

Angular inertial propertiesAngular inertial properties

• This property is referred to as This property is referred to as • Inertia (linear motion)Inertia (linear motion)• moment-of-inertia (angular motion)moment-of-inertia (angular motion)

• not only not only massmass, but , but mass distributionmass distribution

• Varies according to AxisVaries according to Axis• Varies according to mass distributionVaries according to mass distribution

I = m rI = m r22

Moment of InertiaMoment of Inertia

• greater the moment of inertiagreater the moment of inertiagreater inertial load greater inertial load

Greater joint stressGreater joint stress

Example flexed vs straight elbow

Anthropometric Data for Biomechanics for Biomechanics Studies in Industry:Studies in Industry:

• anthropometric data defines the anthropometric data defines the reach and space requirements reach and space requirements of a of a specified population or equipment specified population or equipment user user • modeling and simulationmodeling and simulation

• important consideration for important consideration for workplace workplace designdesign

Making anthropometric measurements in the modern world

Workplace AnalysesWorkplace Analyses

• The book includes tables of The book includes tables of PERCENTILE PERCENTILE data for data for segment lengths, weights, mass-segment lengths, weights, mass-center location, and moment of inertia center location, and moment of inertia based on the general population.based on the general population.

95%5%

50%

z = 1.645z =- 1.645

Example application of Example application of Percentile Tables Percentile Tables ( Table 3.8& 3.9)( Table 3.8& 3.9)

• Table 3.8: Segment lengths as % TBHTable 3.8: Segment lengths as % TBH

• Table 3.9: the mean (50th), 5th and 95th Table 3.9: the mean (50th), 5th and 95th percentile population heights.percentile population heights.

• design must strive to accommodate the design must strive to accommodate the 5th to 95th percentiles (M & F)5th to 95th percentiles (M & F)

• Importance: hand tools, workstation Importance: hand tools, workstation surfaces and seat designsurfaces and seat design

Example: Example: Using USAF men and womenUsing USAF men and women

• New pliers with span of 11 cm (4.3”)New pliers with span of 11 cm (4.3”)• USAF women: average ht = 162.1 cmUSAF women: average ht = 162.1 cm• USAF men: average ht = 177.2 cmUSAF men: average ht = 177.2 cm• Calculate average hand length: Calculate average hand length: (0.108 (0.108

x height)x height)• Females: 162.1 x 0.108 = 17.5 cm (6.9 “) Females: 162.1 x 0.108 = 17.5 cm (6.9 “) • Males: 177.2 x 0.108 = 19.0 cm (7.5”)Males: 177.2 x 0.108 = 19.0 cm (7.5”)

• Male and female Male and female differencesdifferences

• Racial Racial differences differences • (US vs (US vs

Japanese)Japanese)• Specific Specific

population population • (ie source: (ie source:

military, military, NASA, NASA, civilians) civilians)

• number of number of subjects subjects

• source of source of variability (SD) variability (SD) • (ie NASA vs (ie NASA vs

civilians)civilians)

SummarySummary

• Knowledge of anthropometry is importantKnowledge of anthropometry is important

• Anthropometrics is basis of modelsAnthropometrics is basis of models• mass, length, and center of mass of segmentsmass, length, and center of mass of segments

• Design must accommodate 5th to 95thDesign must accommodate 5th to 95th• appropriate sex, race, specific populationappropriate sex, race, specific population

• Will use the tables with future analysisWill use the tables with future analysis