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Body composition assessment issues in
athletes
Duncan Macfarlane
IHP, HKU
Parts of this lecture were based on lecture notes provided by the Lindsay Carter Anthropometric Archive, AUT, NZ
LEARNING OUTCOMES:
1. Why examine body composition
2. Understand the different levels of assessment of body composition
3. Limitations/benefits of using skinfolds
4. Limitations/benefits of using bioelectric impedance (BIA)
5. Limitations/benefits of using of DXA
WHY ASSESS BODY COMPOSITION:
1. Body composition is a component of fitness
2. It can be a screening tool to assess health risk factors
3. To monitor progress and effectiveness of a training program
4. It can be a screening tool to determine what sport someone is most suited to (???)
My “SomatoMac” iPad project 4
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Basic Two compartment model
TBM = FM + LBM
� FM = dissectible adipose tissue + fat, including subcutaneous adipose tissue & deep adipose tissue in stores like large intestine & that surrounding joints.
� LBM = all other tissue + small amount of fat contained within.
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Does fat free mass = lean body mass?
� NO, FFM implies all other tissue minus all fat.
� But practically this is not possible to achieve since fat is present inside tissues such as bone & between fibres & fasciculi of muscle.
Models of body composition
• Two-compartment model is used for sport science
• fat mass and fat-free mass
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Methods to assess body fat
Direct methods: � Dissection
Indirect methods: � Hydrostatic weighing � Dual energy x-ray absorptiometry (DEXA, DXA)
Doubly indirect methods: � Body mass index (BMI) = yuck! � Bioelectrical impedance analysis (BIA) � Skinfold/circumference method
9 BMI � Mass (kg) / square of Height (m)
� Does NOT distinguish FAT v MUSCLE
10 � Body Mass=75 kg � Height= 1.66m � BMI= 27.2 � Overweight??
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Levels of assessment
LEVEL 1: DIRECT ASSESSMENT Jan Clarys et al. Direct anatomical evidence of individual differences. The adipose tissue free tissue mass from 7 female and 6 male unembalmed cadavers dissected 48 hours after demise. Muscle 41.9 - 59.4% Bone 16.5 - 25.7% Residual 24.0 - 32.4%
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Level III Skinfold regression equations
� Follow protocol carefully.
� Between 150 & 200 equations available.
� Choose an equation carefully based on correct population.
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Skinfold assumptions (lead to prediction errors)
� Constant compressibility of skin/tissues. § Two identical skinfolds can have markedly difference subcutaneous fat
due in part to different compressibility (eg. 34% @ front thigh, but 65% @ supraspinale – Brussels cadaver study)
� Skin thickness is constant (within/between people). � There is fixed adipose tissue patterning across limbs
(and people).
� Constant fat fraction in adipose tissue. � Fixed proportion of internal to external fat deposits.
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101520253035404550
SScap Abd SSpin Tri Bic Thi Calf
Subject 1 Subject 2
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Anthropometry � Uses multiple measures. � Skinfolds, girths, lengths of bones,
breadths of bones, height and weight together.
� Restricted (15) and Full profile (42) measures.
� Can take time (10-30min).
It does matter where you take the skinfolds!
Patria Hume and Mike Marfell-Jones
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Hume et al study 2008
Methods
• Cross-sectional quantitative • 12 subjects
• 27.1 ± 6.5 years • 177.3 ± 7.4 cm • 77.8 ± 12.7 kg
• 8 ISAK-specified skinfold sites • 8 points about ISAK = 9 points in 1-cm grid pattern • 3 x each grid point • 2 x ISAK Criterion Level 4 measurers (TEM<1%) • Harpenden skinfold callipers @ 0.1 mm accuracy
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Hume et al study 2008
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Hume et al study 2008
Supraspinale
Triceps Biceps
Iliac crest Abdominal
Subscapular
Calf Thigh
Subscapular showed least # of differences
Abdominal showed most # of differences
Red shows significant differences
Size of the circle is the size of the Cohen effect
Iliac crest shows an anterior trend
22 Body Fat Equa,on Mean Pred %BF Mean DXA (NH) B_A Bias B_A LoA PE % CV % Effect Size
Males
Sloan 1967 8.7 19.2 10.5 4.6 -‐ 16.3 -‐56.6 58.0 1.5
Wilmore 1969 11.2 19.2 8.0 3.7 -‐ 12.3 -‐41.7 37.5 1.5
Katch 1973 9.2 19.2 10.0 6.2 -‐ 13.8 -‐53.3 52.2 1.6
Durnin 1974 13.9 19.2 5.2 0.1 -‐ 10.4 -‐29.0 25.6 1.0
Withers 1987a 9.4 19.2 9.7 5.7 -‐ 13.7 -‐52.5 51.4 1.5
Lean 1996a 10.4 19.2 8.7 3.8 -‐ 13.6 -‐46.8 44.7 1.4
Lean 1996b 12.4 19.2 6.8 0.1 -‐ 13.5 -‐35.0 31.6 1.3
Peterson 2003 16.4 19.2 2.7 -‐1.0 -‐ 6.4 -‐14.6 11.8 0.6
Garcia 2005 9.4 19.2 9.7 1.8 -‐ 17.6 -‐54.1 60.8 1.3
MACFARLANE 2014 23.1 23.1 0.0 -‐5.1 -‐ 5.2 0.2 5.1 0.3
Females
Sloan 1962 21.7 31.0 9.3 3.5 -‐ 15.1 -‐30.2 25.5 1.4
Katch 1968 24.3 31.0 6.7 -‐4.4 -‐ 17.9 -‐22.9 21.6 1.0
Wilmore 1970 24.9 31.0 6.2 0.6 -‐ 11.7 -‐19.5 15.6 1.2
Durnin 1974 28.1 31.0 2.9 -‐2.5 -‐ 8.3 -‐9.4 8.5 0.7
Pollock 1975a 21.0 31.0 10.0 2.7 -‐ 17.3 -‐32.9 28.6 1.4
Lewis 1978 26.1 31.0 4.9 -‐13.1 -‐ 23 -‐19.8 18.2 1.0
Jackson 1980a 20.4 31.0 10.6 3.4 -‐ 17.9 -‐35.4 31.6 1.4
Jackson 1980b 19.8 31.0 11.2 4.6 -‐ 17.9 -‐37.3 33.5 1.4
Thorland 1984 22.0 31.0 9.0 -‐0.5 -‐ 18.6 -‐30.4 27.7 1.2
Withers 1987b 21.4 31.0 9.7 4.4 -‐ 15.0 -‐32.0 27.5 1.4
Withers 1987c/d 20.5 31.0 10.5 6.1 -‐ 14.9 -‐34.4 29.8 1.5
Lean 1996a 24.1 31.0 7.0 0.8 -‐ 13.2 -‐22.4 18.7 1.2
Lean 1996b 24.5 31.0 6.6 -‐1.0 -‐ 14.2 -‐20.1 17.3 1.3
Peterson 2003 27.5 31.0 3.5 -‐2.0 -‐ 9.0 -‐11.4 9.6 0.7
MACFARLANE 2014 31.7 31.5 -‐0.2 -‐8.6 -‐ 8.2 3.7 7.6 0.6
Data on HK Young Adults
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Level III Anthropometry
Advantages: � Convenient and cheap method. � Equipment is portable. � Relatively non-invasive? � Quite good for “follow-up” analysis Disadvantages: � Numerous assumptions - Can take a lot of time for 42 Full sites –
even for 15 Restricted sites � Many equations – they do not agree
§ (%Body Fat equations = wrong; keep as a simple Sum of Skin-Folds) � Requires a GOOD measurer (ISAK L1)
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Level III Bioelectrical Impedance
� Measures total body water, not body fat. � Uses relationship between H20 and fat. � Depends on equation in ‘black box’.
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Level III Bioelectrical impedance
� Hand to foot lying. � Hand to hand standing. � Foot to foot standing. � Muscle electrical activity
filtered out?
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Level III Bioelectrical impedance
� Passes electrical current through electrodes placed on hand, wrist, ankle, and foot.
� Measures resistance to current. � Muscle holds more water so resistance is less than in
fat. � Measures total body water which can be used to
measure fat free mass based on assumption percentage of total body water in fat free mass (73%).
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Level III Bioelectrical impedance
Advantages: � Convenient and rapid method. � Equipment is portable. � Non-invasive. � Correlates well with hydrostatic weighing (0.93). Disadvantages: � Subject must be normally hydrated. � Software is not uniform across machines (racial norms?) � 3-5 % error? – even higher? � - does it monitor changes over time ? (eg. v DXA?)
Are BIA machines reliable? - Yes – but MUST be under identical conditions
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Macfarlane study: DXA v BIA to track changes over 3 months 29
!Table!2.!!Baseline,!change1score!after!intervention!and!statistics!for!BIA!and!DXA!measurements,!as!well!as!comparisons!of!change1scores!(delta)!between!devices:!means!±!SD.!!
! Baseline,!g!
Change!after!intervention,!
g,!(%)!
Change:!!p1value!!(t1test)!
Change:!Effect!size!
Correlation,!r!
(p1value)!Weight!(g)! 65287!±!
13603!1313!±!1500!(10.5%)!
0.008! 0.20!(small)!
!
Fat!DXA!(g)! 21981!±!6589!
1802!±!1096!(13.6%)!
<0.001! 0.16!(small)!
!
Fat!BIA!(g)! 19554!±!6898!
1485!±!1539!(12.5%)!
<0.001! 0.17!(small)!
!
delta1Fat!(DXA!v!BIA)!
! ! 0.003! 0.72!(large)!
0.511!(<0.001)!
Muscle!DXA!(g)!
42561!±!9485!
477!±!966!(+1.1%)!
<0.001! 0.09!(trivial)!
!
Muscle!BIA!(g)!
43255!±!9967!
84!±!1201!(+0.2%)!
0.425! 0.08!(trivial)!
!
delta1Muscle!(DXA!v!BIA)!
! ! <0.001! 0.79!(large)!
0.362!(<0.001)!
Bone!DXA!(g)! 2143!±!392!
7!±!41!(+0.3%)!
0.052! 0.08!(trivial)!
!
Bone!BIA!(g)! 2543!±!496!
14!±!91!(+0.6%)!
0.074! 0.11!(trivial)!
!
delta1Bone!(DXA!v!BIA)!
! ! 0.392! 0.93!(large)!
0.172!(0.047)!
!
%BF by DXA = 33.7%
%BF by BIA = 30.0%
= 3.7% higher by DXA
%muscle by DXA = 65.2%
%muscle by BIA = 66.3%
= 1.1% lower by DXA
Baseline:
Macfarlane study: DXA v BIA to track changes over 3 months 30
!Table!2.!!Baseline,!change1score!after!intervention!and!statistics!for!BIA!and!DXA!measurements,!as!well!as!comparisons!of!change1scores!(delta)!between!devices:!means!±!SD.!!
! Baseline,!g!
Change!after!intervention,!
g,!(%)!
Change:!!p1value!!(t1test)!
Change:!Effect!size!
Correlation,!r!
(p1value)!Weight!(g)! 65287!±!
13603!1313!±!1500!(10.5%)!
0.008! 0.20!(small)!
!
Fat!DXA!(g)! 21981!±!6589!
1802!±!1096!(13.6%)!
<0.001! 0.16!(small)!
!
Fat!BIA!(g)! 19554!±!6898!
1485!±!1539!(12.5%)!
<0.001! 0.17!(small)!
!
delta1Fat!(DXA!v!BIA)!
! ! 0.003! 0.72!(large)!
0.511!(<0.001)!
Muscle!DXA!(g)!
42561!±!9485!
477!±!966!(+1.1%)!
<0.001! 0.09!(trivial)!
!
Muscle!BIA!(g)!
43255!±!9967!
84!±!1201!(+0.2%)!
0.425! 0.08!(trivial)!
!
delta1Muscle!(DXA!v!BIA)!
! ! <0.001! 0.79!(large)!
0.362!(<0.001)!
Bone!DXA!(g)! 2143!±!392!
7!±!41!(+0.3%)!
0.052! 0.08!(trivial)!
!
Bone!BIA!(g)! 2543!±!496!
14!±!91!(+0.6%)!
0.074! 0.11!(trivial)!
!
delta1Bone!(DXA!v!BIA)!
! ! 0.392! 0.93!(large)!
0.172!(0.047)!
!
BIA only measured 61% of the Fat losses seen by DXA
BIA only measured 18% of the Muscle gains seen by DXA
NOTE: Mass dropped only 313g, but Fat loss was 802g, with Muscle gain 477g
= do not use weight scales alone!
WHY is BIA different to DXA:
• All mainly due to “different assumptions” and “different calibrations” – lack of Direct Level 1 criterion comparisons
• Eg. Max car speed = distance/time ; eg. 1km in 18sec = 200kph
Pat Fox + = 250kph ?
NO – the car’s speedometer was not calibrated correctly
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Level II methods: Indirect measurement and use
of assumptions based on qualitative measures
� Underwater weighing - accurate, cheaper, uncomfortable, current ‘gold standard’?
� Medical imaging, CT scan, MRI – accurate, $! � DXA - accurate but $!, future ‘gold standard’?
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Dual energy X-ray absorptiometry (DEXA)
� Primarily used to determine bone mineral density (BMD).
� Can measure regional or total body composition (often using a Fan Beam X-ray – very low dose)
� With further research, could be new gold standard? – some say it already is the gold standard?
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Advantages: � +/-2% error fat, +/-1% error
bone? – better now? � Directly gives % fat without
relying on assumed density. � Low radiation dose. � Minimal effort by subject. � Minimal amount of time
needed to perform. � Gives total or regional values. � Technician does not have to be
trained extensively.
Disadvantages: � Costs HK$600,000 per
scanner. � Computer software is not
uniform for every scanner. � Software values do not
account for extremes of % body fat.
� Software is based on adult values, not all races have norms
� Very obese hard to fit on table (mirror half of them?)
Dual energy X-ray absorptiometry (DXA)
Example of Output 35
Details of Output (BMC/BMD) 36
Details of Output (fracture risk) 37
Details of Output (body comp) 38
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How reliable is DXA?
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But differences can be seen between two scans
Female Athlete – scanned twice within 15 minutes: � 1st scan: % Body Fat = 22.5% � 2nd scan: % Body Fat = 21.5% � In comparison – her “InBody” BIA value = 12% � = Huge difference (and very few elite females are at 12%!!) Myself – scanned twice within 15 minutes: � 1st scan: % Body Fat = 22.8% � 2nd scan: % Body Fat = 23.9%
§ - these 1% total difference in DXA %body-fat are HIGH (not sure if this is due to our aging DXA)
� We have just purchased a new Hologic DXA and happy to check values compared to the HKSI DXA
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But differences can be due to software changes too!
In 2009 Hologic changed their DXA software due to the USA NHANES analysis study (Kelly et al, 2009, PLoS ONE) to increase %body fat by about 4-5%!!
- So comparisons with previous pre-2009 data = almost impossible - aarrgghh!
Female Elite Athlete – same scan – but different software (+/- NHANES adjustment): � Scan using 2008 (pre-NHANES) analysis: % Body Fat = 16.7% (51.5kg Lean tissue) � Scan using 2009 (NHANES) analysis: % Body Fat = 21.2% (48.6kg Lean tissue) � = +4.5%BF = Huge difference (due entirely to different calibration/analysis)
� (another female: pre-NHANES=38.3% v NHANES=41.6 = +3.3%BF difference)
Male non-elite – same scan – but different software (+/- NHANES adjustment): � Scan using 2008 (pre-NHANES) analysis: % Body Fat = 16.1% (64.2kg Lean tissue) � Scan using 2009 (NHANES) analysis: % Body Fat = 20.7% (60.5kg Lean tissue) � = +4.6%BF = Huge difference (due entirely to different calibration/analysis)
� (another male: pre-NHANES=11.8% v NHANES=16.6% = +4.8%BF difference)
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How to minimize variations between scans Two good studies by Nana et al (MSSE, 2012 & 2013)
� 2012 � – showing � Fat mass here only
� concluded none of the changes in body fat were substantial � but consuming the meal did increase lean mass to a small degree
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How to minimize variations between scans Nana et al (MSSE, 2013)
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How to minimize variations between scans Nana et al (MSSE, 2013 - endurance)
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How to minimize variations between scans Nana et al (2013) concluded: � Fat mass – showed small/minimal changes after exercise in both
strength & endurance athletes
� Lean mass – also showed small/minimal changes after exercise in both strength & endurance athletes
� Despite these small/minimal changes – they still suggest athletes should fast overnight and perform a DXA when completely rested in the morning with NO exercise prior § Also – hydration status is important (euhydration) ideally using specific
gravity of urine checked, and void bladder before scan § - These rules were derived for “statistical reasons” rather than for
“functional reasons” – to me the differences are small § - ?? Ideally fast overnight, but if not practical – no exercise prior and no
meal within 2hr?, and ensure a constant level of hydration = more critical
