K. Tolfrey et al., The effect of aerobic exercise training on the lipid-lipoprotein profile of children and adolescents, SPORT MED, 29(2), 2000, pp. 99-112
Longitudinal paediatric population studies have provided evidence that the
risk factor theory may be extended to children and adolescents. These studi
es could assist in identifying individuals at increased coronary risk. Nume
rous stud ies have focused on the effects of regular exercise on the paedia
tric lipoprotein profile, a recognised primary risk factor, with equivocal
results. Cross-sectional comparisons of dichotomised groups provide the str
ongest evidence of an exercise effect. 'Trained' or 'active' children and a
dolescents demonstrate 'favourable' levels of high density lipoprotein-chol
esterol (HDL-C), triacylglycerol, total cholesterol (TC)/HDL-C and low dens
ity lipoprotein-cholesterol (LDL-C)/HDL-C, whilst TC is generally unaffecte
d. The evidence regarding LDL-C in these studies is equivocal. A possible s
elf-selection bias means that a cause-effect relationship between exercise
and the lipoprotein profile cannot be readily established from this design.
Correlational studies are difficult to interpret because of differences in
participant characteristics, methods employed to assess peak oxygen uptake
and habitual physical activity (HPA), and the statistical techniques used
to analyse multivariate data. Directly measured cardiorespiratory fitness d
oes not appear to be related to lipoprotein profiles in the children and ad
olescents studied to date, although there are data to the contrary. The rel
ationship with HPA is more difficult to decipher. The evidence suggests tha
t a 'favourable' lipoprotein profile may be related to higher levels of HPA
, although differences in assessment methods preclude a definitive answer.
While few prospective studies exist, the majority of these longitudinal inv
estigations suggest that imposed regular exercise has little, if any, influ
ence on the lipoprotein levels of children and adolescents. However, most p
rospective studies have several serious methodological design weaknesses, i
ncluding low sample size, inadequate exercise training volume and a lack of
control individuals. Recent studies have suggested that increases in HDL-C
and rejections in LDL-C may be possible with regular exercise. The identif
ication of a dose-response relationship between exercise training and the l
ipoprotein profile during the paediatric years remains elusive.