Material and Methods
Subjects: Two groups of boys aged 12 years were
studied: untrained control group (UC; n = 14), consisting
of boys who attended only the curricular physical
education classes and practiced no sports, and swimming
group consisting of members of school sport clubs who
practiced swimming for two years. They were assigned
into two subgroups: submitted to 8-week training in classical
style (CS; n = 10) or in free style (FS; n = 13). All
parents submitted their signed consents to participation
of their sons in the study which was approved by the
local Committee of Ethics.
Methodology: All boys were subjected to the Åstrand-
Ryhming’s cycle ergometer test before and just after the
training period. Test results served to indirectly assess
the boys’ maximum oxygen uptake using the equation:
Y = 1.444 + 0.522 · ‡O2max (from a nomogram) [11].
The swimmers were additionally subjected to 6 tests:
swimming at 50 and 400 m distances (time recorded) and to 12-min swimming (distance recorded), all by free and
classical styles [4]. Heart rate (HR) was recorded immediately
following every test. From swimming times
at 50 and 400 m distances the so-called critical swimming
speed (CSS) was computed: CSS = (400 – 50) /
(t400 – t50).
Both subgroups of swimmers trained 3 days a week,
every 60-min session consisting of standard warm-up
(10 min), 3 bouts of swimming at CSS, 10 min each,
separated by 5-min intermissions for discussing technical
errors, and relaxation (10 min).