In the Leuven Growth Study of Belgian Boys the growth and physical performance of
Belgian boys followed longitudinally between 12 and 19 years were studied. Subsequently,
a subsample (n = 240) of Flemish-speaking males were reexamined at 30 and 35 years.
A first question relates to the individual growth patterns in a variety of physical
fitness characteristics. The three strength tests (static, functional, explosive)
show curves that are qualitatively similar to those for height and weight. Their adolescent
spurts occur after the height spurt. Flexibility and the two speed tests appear to
reach maximum velocities prior to the height and weight spurts. Longitudinal principal
component analysis was applied to the study of growth patterns of several somatic
and motor characteristics. The results for height show three components sufficient
to provide an adequate representation of the original information. The first component
characterizes the general position of an individual growth curve. Components 2 and
3 reflect fluctuation in percentile level during the age period studied and can be
conceived as indices of stability and are related to age at peak height velocity (APHV)
and peak height velocity (PHV), respectively. Relationships between somatic characteristics,
physical performance, and APHV have been studied in a sample of 173 Flemish boys,
measured yearly between ± 13 and ± 18 years and again as adults at 30 years of age.
The sample was divided into three contrasting maturity categories based on the APHV.
There are consistent differences among boys of contrasting maturity status during
adolescence in body weight, skeletal lengths and breadths, circumferences, and skinfolds
on the trunk. There are no differences in skinfolds on the extremities. None of the
differences in somatic dimensions and ratios among the three contrasting maturity
groups are significant at 30 years of age except those for subscapular skinfold and
the trunk/extremity skinfold ratio. During adolescence, speed of limb movement, explosive
strength and static strength are negatively related to APHV; thus, early maturers
performed better than late maturers. However, between late adolescence and adulthood
(30 years), the late maturers not only caught up to the early maturers, but there
were significant differences for explosive strength and functional strength in favor
of late maturers. Finally, age-specific tracking, using inter-age correlations, of
adult health- and performance-related fitness scores were investigated. In addition,
the independent contribution of adolescent physical characteristics to the explanation
of adult fitness scores was also studied. Tracking between age 13 and age 30 years
was moderately high (46 % of variance explained) for flexibility, low to moderate
(between 19 % and 27 % of variance explained) for the other fitness parameters and
low for pulse recovery and static strength (7 % to 11 % of variance explained). Between
age 18 and age 30 years the tracking was high for flexibility, moderately high for
explosive and static strength, and moderate for the other fitness parameters except
for pulse recovery. The amount of variance of adult fitness levels explained increased
significantly when other characteristics observed during adolescence entered the regressions
or discriminant functions.
Key words
Growth - biological maturation - physical performance - longitudinal - adolescence
- tracking
