Dr Helen O'connor - Losing and making weight for athletes - From science to practice
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Transcript of Dr Helen O'connor - Losing and making weight for athletes - From science to practice
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Losing & Making Weight for Athletes
From Science to Practice
Helen O’Connor PhD APD
Exercise & Sport Science
University of Sydney
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Presentation Overview
• Why athletes need to reduce weight/fat
• Challenges for weight and fat loss
• Strategies for weight and fat loss
• Risks of weight/fat loss
• Making weight
• Weight management tool kit
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Why athletes reduce weight or fat
• Aesthetic Sports
– ‘Right’ appearance is important
– e.g. Body building; gymnastics
• Endurance Sports
– Carry weight over a distance
– e.g. Distance running; triathlon
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Why athletes reduce weight or fat
•Jumping Sports
– Carry weight through space
– High and long jump
•Weight Category Sports
– Competition rule
– Light weight rowing; boxing, martial arts
Note
Most sports consider the additional energy
cost, increased resistance or reduction in
speed or power to weight ratio from excess
body fat when evaluating ideal weight and fat
levels for their sport.
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Differences within one Sport
Difference in physique
apparent on casual
observation
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Physique and Running
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Physique & Swimming
Dawn Frazer 100 mtr Freestyle
Olympian 1956, 1960, 1964
Shane Gould 1972 5 Olympic Medals
Freestyle & IM
Libby Trickett 2009 Olympian
Freestyle & Fly
Getty Images
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Morphological Optimisation
Quantified using three kinds of comparisons
• Athlete versus source population
• Competition level gradients
– ‘Best’ versus ‘Rest’ analysis
• Comparison across time
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Athlete vs Source Population
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‘Best’ vs “Rest’ Analysis
59
60
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68
I S C
Competition Level
We
igh
t (K
g)
International and Australian 5000-1000 m runners across competitive levels
(unpublished data): I: International; S: State: C: Club
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Mechanisms for Optimisation
Selection
•Height, lengths
•High Jump
•Height & high centre of gravity
Adaptation Mass, fat & lean
Mass energy expenditure
Body fat power: weight
Improved heat exchange
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Mechanisms for Optimisation
Heat Exchange
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Physique & Performance
Olympic Games 1968
Richard ‘Dick’ Fosbury
The Fosbury Flop Technique •curved run-up allows more speed to
do a more powerful jump
•the centre of gravity is underneath,
an indisputable mechanical
advantage.
10 cm Increase in height of male
competitors over 2 Olympiads Uwe Hohn 1984 Games
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Does weight/fat loss
improve performance?
• Limited research data (p values)
• Hard to measure effect small weight/fat changes
• Olds et al 1993 (mathematical modeling)
4000 m Pursuit Cycling
– 2 kg body fat 1.5 s (20 m)
40 km Time Trial
– 2 kg body fat 15 s (180 m)
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Weight & Fat Loss
• Challenges
• Strategies
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Challenges for
Weight or Fat Loss
Challenges for weight or fat loss
• Genetic predisposition
• Gender & pubertal influences
• Media pressures
• Training & appetite
• Tapering
• Under-reporting or energy
deficient?
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Heritability of Adiposity
Author Year n Age Heritability
Feinleibet et al 1977 514 Adult 0.64
Fabsitz et al 1980 1028 Adult 0.80
Stunkard et al 1986 4071 Adult 0.77
Bouchard et al 1987 156 Adult 0.10
Bodrtha et al 1990 259 11 0.54
Korkeila et al 1991 7245 Adult 0.73M; 0.68F
Maes 1992 105 Adult 0.89M; 0.49MF
Allison et al 1994 496 Adult 0.93
Bowen et al 1997 105 10-14 0.90
Reviewed Keller et al 2003
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Gender & Pubertal Development
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Media Influences
'Size zero' causes racket
Daniela Hantuchova
"In tennis, as in all women's sport, there is a lot of
talk about women's bodies”.
“People are looking at your body the whole time.
A male athlete is allowed to be overweight, that's
no big deal”.
“But for a female athlete to be overweight, now
that's seen as the worst thing in the world”.
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Detraining and Fat Gain
Elite female swimmers
• Rest period (2 months)
• 4.8 kg body weight gain
• Energy equivalent = 170 MJ
• 170 MJ = training EE
• Energy intake not spontaneously reduced
Almeras et al 1997. `
McConell et al 1993 Distance runners
4 week progressive taper, fat increased 10.4-11.8%
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Other Issues with Taper
• Habitual Energy Expenditure
– Usually reduced
• Time
– More time
– Eating when stressed or bored
• Eating away from home
– Meals may be more energy dense
– Buffet food service, free, new, interesting foods – ‘try it’
• Incorrect competition advice
– ‘Fuel up for competition’
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Strategies for Weight or Fat Loss
• Macronutrient
manipulation
• Energy Density
• Food variety
• Glycaemic Index
• Role of dairy
• Gut microbiota
• Adjunctive agents
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Why Low CHO Diets?
• Currently popular
• Athletes/coaches – Frustrated with weight/fat loss
– Like something ‘newer’
• Claims for substantial weight loss – Longer term safety?
– Effectiveness?
– Performance?
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Comparison of
Atkins, Zone, Ornish & LEARN
-6
-5
-4
-3
-2
-1
0
0 2 6 12
Time (months)
Mean W
eig
ht C
hange (
Kg)
Zone
LEARN
Ornish
Atkins
Gardner et al 2007
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25
High Protein Diets & Weight Loss
Wycherley et al 2012
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Diogenes Weight Maintenance
LP-HGI &
Control
Most Weight
Regain
HP or LGI
alone
moderate
benefit
0.93 kg less
gain in HP &
0.95 kg less
in low GI
HP-LGI
best
Larsen et al 2010
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How Much Protein Do We Need?
• Evidence of a ‘set point’ requirement for protein
• Different requirement across species
• Eating continues until protein requirement is reached
• Known as ‘Protein Leverage Hypothesis’
Case Example
• Energy Needs 10,700 kJ/day
• Estimated protein requirement (1500 kJ/day)
• Remainder from carbs and fat (9,200 kJ/day)
• You keep eating until protein intake is satisfied
Excess CHO/Fat
consumed to meet
Protein target
Eaten quota of CHO + Fat but still
eating to get Protein requirement
Eaten quota of kJ but still short of protein
Simpson & Raubenheimer 2005
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Energy Density Vs Fat
0
2
4
6
8
10
12
14E
ne
rgy
In
tak
e (
MJ
)/d
Calorimeter VED Free-Living VED Free-Living CED
Impact of dietary fat content on spontaneous food intake under different
experimental conditions (ED = energy density). Stubbs et al 1995
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Food Variety
• Diets matched ED & macronutrient content
• Containing either 5, 10 or 15 items
• 6 day duration
• Energy intake increased (400 kcal/d) with variety
• Fad Diets typically have low food variety
• Monotony may be a short term strategy
Stubbs, 2001
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Low GI Meals are More Satiating
0
1
2
3
4
5
6
7
Low GI Medium GI High GI
En
erg
y i
nta
ke f
or
rem
ain
der
of
the
day (
MJ)
P<0.05
Voluntary food intake of 12 obese teenage boys following test breakfast & lunch of varying GI
Ludwig et al 1999
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Dairy Intake &
Weight & Fat Loss
0
1
2
3
4
5
6
7
Weight Body fat Lean mass
Lo
ss (
kg
)
Control
Yoghurt
Zemel et al 2005
* P < 0.005
* P < 0.01
* P < 0.05
38 obese adults,
500 kcal deficit
12 weeks
Control diet
0-1 dairy &
400-500 mg
ca2+/d.
Yoghurt diet
3 x 180 g
serves RF
yoghurt & 500-
1100mg ca2+/d
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Dairy Calcium & Weight: Systematic review
Abargouei et al 2012
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Dairy & Adiposity Mechanisms
Dietary Calcium and/or Dairy Products
Available Energy Energy Utilisation
Increased Satiety
Ca2+- Fatty Acid Soaps
Lipolysis
Lipid Oxidation
Energy Expenditure - TEF
Adapted from Teegarden 2005
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Is Excess Body Fat
Just a BUG in the GUT?
Slides compliments of A/Prof Gareth Denyer
http://www.youtube.com/watch?feature=endscreen&NR=1&v=pB5AFW7X5F8
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Gut Microbiota & Obesity
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Adjunctive Agents
• Dietary supplements
– L-Carnitine
– Chromium picolinate
– Hydroy-methyl-butarate (HMB)
– Conjugated linoleic acid (CLA)
– Herbal supplements
• Pharmacotherapy
– Not permitted
– Not recommended due to side effects
– Ethically appropriate (designed for the obese)
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Risks of Weight or Fat Loss
• Endocrine disturbance
• Bone loss
• Weight cycling
• Reduced lean mass
• Illness and immunity
• Disordered eating
• Decreased performance
– ‘the runners trap’
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Female Athlete Triad Amenorrhoea
Osteopaenia
Low body
fat or weight
Inadequate energy
Inadequate protein, fat
& micronutrients
High fibre
Heavy training
Body Temperature
Hormone pulsatility Disordered
Eating
Lisa
Corrigan
1500 m
Suzie
Rhydderch
1500 m
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Energy Deficiency
Energy Deficiency
(decreased energy availability)
• Inadequate available energy
• < 125 (30 kcal)/kg FFM/d
• Amenorrhoea
• Bone mineral loss
• Misclassified as under-reporters
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Energy Deficiency
Periodise Physique
“I need to eat
a lot less to be
lean”
Energy for body functions
Energy
Intake
Energy Burnt Training
- = Regular
Menstrual Cycle
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IOC healthy Body Image U-Tube
41
Anezka Ruzucka
Gymnastics, Ukraine
Aiko & Tochi Nakata
Figure Skating Japan
Jessie-lee Nelson
Wrestling USA
Akeyo Abasi
Athletics Kenya
http://www.olympic.org/hbi
Satisfying
your hunger
for GOLD
requires
satisfying
your body’s
need for fuel
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‘Making Weight’ Issues
• Weight often lost rapidly prior to competition – Fluid loss or restriction (sauna, rubber suits)
– Food restriction, fasting
– Diuretics, laxatives, vomiting
• Intention is to ensure ‘level playing field’ – Larger athletes still aim to make a lower weight
– Sports vary in the number of categories available
• Competitive success – Defeat opponent rather than personal best
– Use strategies to optimise weight regain
– Negative impact varies depending on sport & weight loss
methods used (> energy + fluid restriction)
http://www.youtube.com/watch?v=x1Plo_5HS
Vw&feature=relmfu
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‘Making Weight’ Strategies
• Dehydration – Banned by NCAA for wrestlers
– Aim for no more than 2% body mass
• Diet – Rapid weight loss
• Greater loss of lean mass
• Greater loss in performance
– Adequate carbohydrate to maintain performance
– Protein requirement with energy restriction (~1.2 g/kg)
– Low residue diet
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Making Weight
Recovery Strategies
• Electrolytes
– Sodium at least 50 mM
• Diet
– High carbohydrate (replace glycogen stores)
– High GI carbohydrates
Note
The need for rapid weight loss can be minimised by developing a plan for the competition
season which gradually reduces weight within easy reach of the desired level.
In the ‘off season’, athletes should aim to prevent excessive weight rebound.
MSSE Position Stand for Weight Loss in Wrestling:
http://www.ms-se.com/pt/pt-core/template-journal/msse/media/0696b.pdf
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Weight Management Tool Kit • Anthropometry –ISAK Training
• Food & Activity History
– Check for lounge Lizards
– Food diary (is it plausible ?)
– Food triggers, psychological issues (body image)
• ‘Test diet’ (prescriptive) + diary
• Incorporate…
– Periodised program
– Meals vs snacks (sit and eat at table)
– Low fat, right CHO, adequate protein & dairy
– Low GI, high fibre, for hungry athletes
– Short term restriction in variety to prove efficacy
– Hunger, satiety and CBT approach (VAS)
– Energy levels and vitality (VAS)
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Low Energy Availability
Dietary intake (I) and exercise energy expenditure (E) were controlled to achieve
a balanced (B = 45 kcal/kg FFM/day) and deprived (D 10 kcal/kg FFM/day)
energy availability (A = I-E) treatments. D was achieved by diet restriction in
sedentary (S) women and by exercise in active (X) women
(a) Luteinising hormone (LH) pulse frequency in sedentary (S) and exercising (X)
women with the same energy availability. (b) Reduction in LH pulse frequency
caused by low energy availability in (S) and (X) women P < 0.01 Loucks et al 1998
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Low Energy Availability
Women were assigned to contrasting EA 45 and 10, 45 and 20 and 45 and 30 kcal/kg.
All participants performed 15 kcal/kg FFM/day of exercise at 70% VO2 max under
supervision while energy intake was controlled to achieve the intended EA treatments
Incremental effects of low EA on LH pulse amplitude and frequency. Effects are expressed
relative to values at 45 kcal/kg FFM/day. As EA declines from a balance at approximately
45 kcal/kg FFM/day effects begin at a threshold at around 30 kcal/kg FFM/day and become
more extreme as EA is further reduced below 20 kcal/kg FFM/day Loucks et al 1998