The most notable change during the taper period
is a marked increase in muscular strength, which explains at least part of the
performance improvement that occurs. It is difficult to determine whether
strength improvements result from changes in the muscles’ contractile mechanisms
or improved muscle fiber recruitment. However, examination of individual muscle
fibers taken from swimmers’ arms before and after 10 days of intensified
training showed that the type II(fast-twitch) fibers exhibited a significant
reduction in their maximal shortening velocity. This change has been attributed
to changes in the fibers’ myosin molecules. In these cases, the myosin in the type II fibers became more like that in the type I fibers. We assume from this
finding that such changes in the muscle fibers cause the power loss that
swimmers and runners experience during prolonged periods of intense training.
We can also assume that the recovery of strength and power that occurs with
tapering is linked to modifications of the muscles’ contractile mechanisms.
Tapering also allows time for the muscle to repair any damage incurred during
intense training and for the energy reserves(i.e. , muscle and liver glycogen)
to be restored.
Although tapering is widely practiced in a
variety of sports, many coaches fear that reduced training for such a long
period before a major competition will decrease conditioning and impair
performance. But numerous studies clearly show that this fear is unwarranted.
Developing optimal VO2max initially requires a considerable amount
of training, but once it has been developed, much less training even when
training frequency is reduced by two-thirds.
Runners and swimmers who reduce their training
by about 60% for 15 to 21 days show no losses in VO2max or endurance
performance. One study showed that swimmers’ blood lactate concentrations after
a standard swim were lower after a taper period than before. More important,
the swimmers experienced a 3.1% improvement in performance as a result of the
reduced training and demonstrated a 17.7% to 24.6% increase in arm strength and
power.
In a study of distance runners, those runners
who went through a seven-day taper decreased their running time in a 5km time
trial by 3% compared to no improvement in those who did not taper. Submaximal oxygen
uptake during running at 80% VO2max was decreased by 6% in those who
tapered, indicating a greater economy of effort. Blood lactate concentrations
at 80% of VO2max were unchanged, as were VO2max and leg
extension peak force.
Unfortunately, little information is available
to demonstrate the influence of tapering on performance in team sports and in
long-duration endurance events such as cycling and marathon running. Before
guidelines can be offered for athletes in these sports, research is needed to demonstrate
that similar benefits can be generated by such periods of reduced training.
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