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).