Biomechanics and Medicine in Swimming XI

BiomechanicsandmedicineinswimmingXi
utilised the glide co-ordination throughout the swim. The glide coordination
is characterised by a positive transition time meaning that
there is a delay from the end of the kick propulsion phase to the start of
the arm propulsion phase. This corresponds to a period of no propulsion
in the swimming stroke. The glide co-ordination is normally associated
with swimming the 200 m breaststroke (Leblanc et al., 2009; Soares
et al., 1999). Nine of the participants used the overlap co-ordination
throughout the swim, which is characterised by a negative transition
phase meaning that the arm propulsion phase starts before the end of
the leg propulsion phase. Swimmers adopt this co-ordination pattern as
it has been shown to reduce velocity fluctuations and helps maintain a
higher mean velocity (Seifert & Chollet, 2005).
The transition phase changed in the majority of participants from
the 1 st to the 4 th lap. Eighteen of the participants either increased the
amount of overlap within their stroke (n=5), changed from glide to
overlap co-ordination (n=5), or decreased the time spent in the glide
phase of the stroke (n=8). The remaining participants altered their coordination
in the other direction by increasing the amount of glide (n=8)
thus showing an increase in transition time.
These changes in the participant’s co-ordination are likely to be a
result of fatigue. Fatigue has been shown to hamper the sensorimotor
system, affecting such functions as awareness, feedback and coordination,
which maintain form and stability, resulting in the inability
to maintain ideal mechanics (Toussaint et al., 2006). This means that
as the participants become fatigued, as the race distance progresses,
they change their co-ordination pattern therefore causing the participants
to move towards or increase the overlap co-ordination in their
stroke. These alterations in co-ordination could be a direct result of the
participants trying to maintain homeostasis through compensatory
mechanisms of the neuromuscular system to maintain effective mechanical
power output. It is hypothesised that the results of the study
suggest that the participants are becoming less mechanically efficient
as the swim progresses as there is a significant decrease in clean swim
speed from the 1 st to the 4 th lap and subsequent decreases in stroke
length and stroke rate (table 1).
conclusIon
The findings of this study give us a better understanding of the effects
of fatigue and the subsequent changes that occur in the co-ordination of
the arms and legs in 100 m breaststroke swim.
As the participants fatigued they decreased the transition phase of
the stroke by either increasing the amount of overlap or reducing the
glide phase of the stroke in an attempt to maintain clean swim speed.
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