Biomechanics and Medicine in Swimming XI

RESULTS
Table 1 shows the physical characteristics, Vcri and correlation coefficient
in swim, pull and kick for each subject.
The experimental plots used to determine Vcri of subject 1 are shown
in Fig. 1 as an example. The relations between distance (D) and time (T) in
swim, pull and kick were expressed in the general form, D = a + b x T, with
r2 value (goodness of fit) showing higher than 0.998 (p0.998) in all strokes for every subject,
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so that the relationship D = a x T + b, was remarkably linear. These
findings mean that the concept of Vcri is applicable to pull and kick as
well as swim, and the obtained Vcri-p and Vcri-k could be also useful
assessment for endurance capacity in arm stroke and leg kick, which can
obtain without requiring blood sampling or the use of highly expensive
equipment.
Wakayoshi et al. (1992a, 1992b, 1993) revealed that Vcri observed
in swimming significantly correlated with several indices for endurance
capacity, such as oxygen consumption at anaerobic threshold, the
swimming velocity at the onset of blood lactate accumulation and the
mean velocity of 400 m freestyle. Moreover, they have suggested that
Vcri, which is calculated by the times of 200m and 400m in the normal
pool, would correspond approximately to the exercise intensity at
MLSS. Supporting those previous findings, all subjects in this experiment
could maintain the Vcri for 20 min in all strokes, and the values of
BL showed almost a steady state while the MLSS test, that is, there was
no significant difference among the mean values of BL after each stage
in each stroke. Furthermore, the values of BL at each stage were not
significantly different among strokes. The results of this study suggest
that the Vcri determined by pull and kick as well as swim correspond
approximately to the intensity of MLSS and that those measurements
could provide useful guideline for setting an appropriate intensity for
endurance training for arm pull and leg kick.
Interestingly, Vcri-p observed in this experiment was almost equal or
rather higher when compared to Vcri-s. This might be explained by the
use of pull-buoys while pulling thus enabling more efficient stroking in
Vcri-p as compared to Vcri-s.
Since Vcri is a certain index for endurance capacity, this result implies
that the propulsion for whole stroke is generated mostly by the
arm action as the swimming distance becomes longer. This conjecture
is in line with the results of BL in MLSS tests, that is, the values of
BL in pull were almost equal to those in swim (4-5 mmol•l-1), but
those in kick (6-7 mmol•l-1) tended to be higher, suggesting that the
metabolic demand for leg muscles during swim should be much lower
than that during leg kick. On the other hand, maximal speed in swim is
generally higher than that in pull. Therefore, leg kick should contribute
the generation of the total propulsion of the swim, especially in sprint
event. Actually, in the short lasting exhaustive swimming (