Saddleback Journal of Biology - Saddleback College

Mass Specific Lactate
Level (mmol/L·Kg)
0.15
0.1
0.05
0
Time (min) * At Rest
Figure 2 – Lactate level (mmol/L·kg) versus time
(min). A one tailed, paired t-test revealed that there is
no significant difference of lactate levels at different
times (p=0.38). Included are error bars ±SEM.
Figure 3 – Average heart rate (beats/min) versus time
(min). One tailed, paired t-test showed no significant
difference (p-value= 0.36).
Discussion
Our results support our hypothesis indicating
that a cool down during recovery will remove lactate
more rapidly than not performing a cool down. Cool
down following 500 yards warm up and a 100 yards
sprint resulted in greater lactate disappearance than
without a cool down (Fig. 1). Asselin, of Medicine &
Science in Sports and Exercise found that active
recovery immediately after the strenuous exercise
encourages recovery and reduces muscle lactate levels
faster than complete rest (Asselin et al., 2006). This is
due to swimming an aerobic lap instead of an anaerobic
sprint. Swimming the cool down lap will allow for the
lactate produced by the cells in your body to diffuse
into the blood stream and flow to different parts of the
body. The lactate will then be taken into the
mitochondria of different organs (i.e. the heart and the
liver) by monocarboxylate (MCT) transport proteins.
These proteins shuttle the lactate across lipid bilayer
membranes so that it can be oxidized into pyruvate by
Fall 2009 Biology 3B Paper
111
Saddleback Journal of Biology
Spring 2010
mitochondrial lactate dehydrogenase (mLDH). The
oxidation of lactate into pyruvate allows the body to
convert pyruvate into cellular energy or more
specifically, ATP (Hashimoto et al. 2006).
Consequently, the conversion of lactate decreases its
levels in the body and that is the reason for the quicker
lactate recovery rates in swimmers who do a cool
down.
Test subjects who swam cool down laps after
intense exercise had higher lactate levels in their blood
compared to swimmers who did not perform cool down
laps. The reason more lactate increases in the blood
was because at longer distances, lactate has less time to
be converted by the human body. As the graph shows
(Figure 2) the slope for swimming with a cool down is
steeper which means the lactate recovery rate is
quickly going back to the baseline blood lactate level
of the individual. The intensity of the cool down
affects how quickly lactate is removed (Cerretelli et
al., 1999). When you swim a cool down, you
maintain a higher level of blood flow—this higher
level increases the rate that lactate is removed from
your muscles. It also tends to increase the rate at
which your muscles can utilize that lactate. However,
there is a gap in the line that shows average blood
lactate without a cool down, which is due to the time it
takes for lactate in the blood to travel through the
blood vessels. While swimming, you are working out
the arms and legs and that is where blood lactate is
building up; however, in this experiment blood
samples were taken from the tip of the finger.
Additional lactate may be produced if the intensity is
too light. At too low of an intensity, lactate may not
create enough circulation to remove lactate faster than
no cool down would (Medbo, 1993). Consequently,
the time for the lactate to travel through the body to
your finger tips took longer.
In Figure 3, the average heart rate of each
individual was plotted versus time. In swimming with a
cool down, the average heart rates are higher compared
to swimming without a cool down—thus, we can infer
that the heart is beating faster when doing a cool down.
With an increase in heart rate we can assume that the
individual is working harder.
In conclusion, an active cool down recovery
suggest that coaches should consider incorporating a
recovery cool down during hard training sessions. The
removal of lactate takes approximately one hour but
this can be increased by undergoing a cool down that
ensures a fast and continuous supply of oxygen to the
muscles (Medbo, 1993).
Acknowledgements
We would like to thank Professor Steve Teh
for providing us with the knowledge to take on this
project. We would also like to thank the Saddleback