fit or fat? adiposity, physical activity, insulin...

Fit or fat? Adiposity, physical activity, insulin resistance and blood pressure in

children

George P. Nassis, MSc, PhD

Department of Sports Medicine and Biology of ExerciseFaculty of Physical Education and Sports ScienceNational and Kapodistrian University of Athens

Greece

Fitness versus fatness

•Prevalence of childhood obesity is increasing over the last years•Excess adiposity is associated, among others, with insulin resistance, vascular and CNS dysfunction, elevated blood pressure etc•Fitness and in particular of aerobic type may counteract some of these effects of obesity on health

Association between inactivity and adiposity

Maffeis et al. J Pediatr 1997;131:288-92

Association between physical activity, fitness and adiposity

Rowland et al. J Appl Physiol 1999;86:1428-35

The role of aerobic fitness

Nassis et al (2005) Eur J Clin Nutr 59:137-141

0

10

20

30

40

50

60

70

80

Non-overweight Overweight/obese

Su

m o

f tr

un

k s

kin

fold

s

(mm

)

UNFIT

FIT

b

#

#

Nassis et al (2005) Eur J Clin Nutr 59:137-141

The role of aerobic fitness

The role of aerobic fitness

Lee & Arslanian (2007) Eur J Clin Nutr 61:561-565

Conclusion

It seems, therefore, that aerobic (cardiorespiratory) fitness has an independent role on risk factors in overweight and obese children and

adolescents

0 30 60 90 1200

2

4

6

8

10

Time (min)

Pla

sma

glu

cose

(m

mo

l/l)

Pre

Post

Nassis et al. (2005) Metabolism 54:1472-9 Metabolism 54: 1472-9

Plasma glucose responses during the 2-hour OGTT before andafter 12 weeks of aerobic training in overweight and obese girls.Mean±SE

0 30 60 90 1200

20

40

60

80

100

120

140

160

**

Time (min)

Ser

um

in

suli

n (

U/m

l)

Pre

Post

Serum insulin responses during the 2-hour OGTT before and after12 weeks of aerobic training in overweight and obese girls . Mean±SE,**P< 0.01 vs post-intervention

Nassis et al. (2005) Metabolism 54:1472-9 Metabolism 54: 1472-9

Conclusion

It appears that an increase in cardiorespiratory fitness may improve insulin sensitivity without changes in

body weight and adiposity in overweight and obese children

The Fitness vs Fatness debate

Larson-Meyer et al. (2010) Med Sci Sports Exerc 42:152-159

Effect of diet and physical training on body composition

Larson-Meyer et al (2010) Med Sci Sports Exerc 42:152-159

Effect of physical training on risk factors

Larson-Meyer et al. (2010) Med Sci Sports Exerc 42:152-159

FFM and insulin resistance

-1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5

-14000

-12000

-10000

-8000

-6000

-4000

-2000

0

2000

4000

6000

8000

10000

r= -0.68, p< 0.001

Ch

an

ge

in i

nsu

lin

AU

C

(Post

-Pre

,

U.m

in/m

l)

Change in lower limbs FFM (Post-Pre, kg)

Nassis et al. (2005) Metabolism 54:1472-9 Metabolism 54: 1472-9

Heitmann et al (2009) BMJ 339:b3292

Muscle mass and risk factors

Heitmann et al (2009) BMJ 339:b3292

Is there a threshold for muscle mass to observe beneficial effects on health?

Muscle mass and risk factors

Is there a threshold for cardiorespiratory fitness to observe beneficial effects on health?

It seems that there is a critical weight loss to observe significant improvements

in insulin resistance in obesity

-20

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

Bo

dy w

eig

ht

ch

an

ge

fro

m b

aselin

e

(%)

D S *

Period

3 months 6 months

Florakis et al (2009) Int J Obes 32:692-9

It seems that there is a critical weight loss to observe significant improvements

in insulin resistance in obesity

Florakis et al (2009) Int J Obes 32:692-9

600

700

800

900

1000

Baseline 3 months 6 months

Glu

co

se A

UC

(m

mo

l x m

in/L

)

D S

a

How much improvement in cardiorespiratory (CR) fitness is enough for insulin sensitivity increase?

0 10 20 30 40 50 60 70

Larson-

Meyer et al,

2010

Nassis et al,

2005

Ribeiro et

al, 2005

Bell et al,

2007

van der

Heijden et

al, 2009% improvement in insulin

sensitivity

% Increase in CR fitness

How much improvement in cardiorespiratory (CR) fitness is enough for resting blood pressure

reduction?

0 20 40 60 80

Larson-Meyer et

al, 2010

Farpour-

Lambert et al,

2009

Gutin et al, 2000

Bell et al, 2007

Kriemler et al,

2010

% reduction in Systolic

BP

% Increase in CR Fitness

Effect of cardiorespiratoyr fitness and obesity on risk factors (insulin resistance, blood pressure)

Total body and

central adiposity

Cardiorespiratory

fitness

FFA, leptin,

Other factorsCNS function Insulin resistance

Vascular

function

Elevation in resting

blood pressure

Excess increase in blood pressure

during sympathetic activation

• ?

Physical activity or fitness?

Which is the most important?

Conclusions

•Exercise at moderate to vigorous intensity, that increases aerobic fitness, should be the target in pediatric population

Conclusions

•In addition, the promotion of a physically active lifestyle in overweight youth is important in reducing the risk of subsequent disease in the absence of weight loss

Study group

•Professor LS Sidossis, Harokopio University•Professor N Geladas, Athens University•Professor G Chroussos, Athens University•Ass Prof S Kavouras, Harokopio University•Ass Prof M Yannakoulia, Harokopio University•K Papadakou, MSc, Harokopio University•K Skenderi, PhD, Harokopio University•M Krekoukia, MSc, Harokopio University•G Psarra, PhD, Harokopio University•C Legantis, MSc, Athens University

Conclusions

•Elevated physical activity and cardiovascular fitness are associated with reduced adiposity in youth

•An increase in aerobic fitness is associated with improved insulin sensitivity in obese children. This effect might be without changes in total and central adiposity

Individual responses

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

-60 -40 -20 0 20 40

AA

% αλλαγή ζηο εμβαδόν ηης περιοτής κάηω από ηην καμπύλη ηης ινζοσλίνης•% change in insulin AUC

Nassis et al. (2005) Metabolism 54:1472-9 Metabolism 54: 1472-9

•Kriemer??

Physical activity or fitness?

Which is the most important?

Rowland et al. J Appl Physiol 1999;86:1428-35

Evidence

•Cross-sectional studies•Intervention studies

Physical activity or fitness?

Which is the most important?

Kriemler et al. BMJ 2010 340:c785

Questions

•Is reduction in fatness necessary in light of adequate fitness (aerobic)?•Does improvement in fitness or fatness independently change risk factors for CVD and metabolic syndrome?•Is the intensity of physical activity important?•Is physical activity more important than fitness?