Biomechanics and Medicine in Swimming XI

ARV value of the fitted curve at the time of the first and the last stroke
were computed. For the frequency analysis mean frequency (MNF) was
calculated. The values of MNF were plotted as a function of time. Linear
regression analysis was applied to obtain the initial value (the value of
MNF at the time of the first stroke) and the final value (the value of
MNF at the time of the last stroke), labelled MNF Sbeg and MNF Send respectively.
In order to normalize results between subjects the final values
were expressed as a percentage of the initial values and labelled MNF n.
Descriptive statistics and repeated measures ANOVA, with subsequent
Tukey’s test for post-hoc analysis were used for multiple comparisons
between the groups.
results
The average blood lactate values collected before and 1, 3 and 5 minutes
after the swim were 1.8 ± 0.6, 6.7 ± 1.47, 12.7 ± 2.2 and 14.1 ±
2.93 mmol.l -1 respectively. The highest lactate value collected was 17.7
mmol.l -1 .
Stroke rate (SR), stroke length (SL) and SS (S) are shown in Table 1
Table 1. Stroke length (SL), stroke rate (SR) and swimming speed SS
(S)
SL(m) SR(stroke*min-1 ) S(m/s)
Distance (m) av. SD av. SD av. SD
25 2.00 0.13 50.56 4.15 1.68 0.08
50 2.02 0.16 47.12 5.33 1.58 0.09
75 1.94 0.14 46.32 4.54 1.49 0.06
100 1.89 0.18 45.77 4.71 1.43 0.08
The ARV calculated for LD2 and TB increased significantly at the end
of the swimming with respect to the beginning of swimming as shown
in Figure 2, left.
Fig.2. Left: Comparison of the amplitude (ARV) of the EMG signal at
the beginning and the end of 100 m all-out swim. Right: Mean MNF
values with SD of MNF Sbeg and MNF Send for all muscles *p < 0.05.
The differences between the MNF Sbeg and the MNF Send , were significant
for all muscles (p