1. Cordiel Brown
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Name:Cordiel Brown
Date:February 8, 2013
ID#620058517
Course:MBBS
Title:Elevation of Blood Lactate During Exercise
Introduction:During vigorous exercise lactate is produced faster than the ability of the tissues to
remove it so the lactate concentration in the blood increases. The increased lactate can then be
removed and converted into glucose. Glucose is used for energy production during aerobic
metabolism to produce pyruvate, ATP, NADH and H+ ions. However with prolonged muscle activity,
oxygen is not always readily available for oxygenation of glucose. Here, anaerobic glycolysis occurs and
pyruvate is further converted to lactate by the enzyme lactate dehydrogenase.
HNADHpyruvatelactateNAD aseDehydrogenLactate
Aim: To determine the concentration of lactate in the blood of individuals (males) before and
after exercise.
Method: As written in DD120 laboratory manual, 2013; pages 5-7
Results:
Table showing Absorbance of lactate in blood at 366 nm for participant 1
Sample Absorbance Blank Corrected Absorbance
Standard 0.112 0.047 0.065
Blood Before Exercise 0.156 0.063 0.093
Blood After Exercise 0.167 0.061 0.106
Sample calculation: standard
Dilution factor #1= (2.0+1.0)/1.0=3.0
Dilution factor #2= 3.4/0.1=34 A = Absorbance /OD units
343.0
l
A
c ε = 6.22×10 3
L/cM. Mole
c = mole/L
L= 1 cm

2. Cordiel Brown
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343.0
l
A
c
C = 0.065/6.22 x 10-3
x 1
C = 1.045
Accurate conc. = 1.045 x 3 x 34
= 1.066 x 10-3
mole/L
Table showing Absorbance and Lactate Concentrations for before and after exercise for the class at
366nm
Sample Absorbance Lactate concentration Status Gender
Before After Difference Before After Difference
A.M 0.093 0.106 0.013 1.53 x 10-3
1.73 x 10-3
2.13 x 10-4
Fit Male
S.E 0.072 0.097 0.025 1.18 x 10-3
1.59 x 10-3
4.10 x 10-4
Fit Male
O.B 0.050 0.069 0.019 8.20 x 10-4
1.13 x 10-3
3.12 x 10-4
Fit Male
S.D 0.073 0.083 0.010 1.20 x 10-3
1.36 x 10-3
1.64 x 10-4
Fit Female
J.A 0.068 0.070 0.002 1.12 x 10-3
1.15 x 10-3
3.28 x 10-5
Fit Female
R.R 0.024 0.051 0.027 3.94 x 10-4
8.36 x 10-4
4.43 x 10-4
Fit Male
K.B 0.042 0.055 0.013 6.89 x 10-4
9.02 x 10-4
2.13 x 10-4
Fit Female
Sample calculations:
Lactate concentration for males
Before exercise
343.0
l
A
c
C = 0.093/6.22 x 10-3
x 1
C = 1.50 x 10-5
Accurate conc. = 1.50 x 10-5
x 3 x 34
= 1.53 x 10-3
mol/L
After exercise

3. Cordiel Brown
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343.0
l
A
c
C = 0.106/6.22 x 10-3
x 1
C = 1.70 x 10-5
Accurate conc. = 1.70 x 10-5
x 3 x 34
= 1.73 x 10-3
mol/L
Difference
343.0
l
A
c
C = 0.013/6.22 x 10-3
x 1
C = 2.09 x 10-6
Accurate conc. = 2.09 x 10-6
x 3 x 34
= 2.13 x 10-4
mol/L
Table showing average Lactate concentrations for male and females
Sample Averages ( )
Male Before exercise 9.81 x 10-4
Female Before exercise 1.00 x10-3
Male After exercise 1.32 x 10-3
Female after exercise 1.14 x 10-3
Male difference (before – after) 3.45 x 10-4
Female difference (before - after) 1.37 X 10-4
Sample calculations:
Male before exercise average
Male B.E =
(1.53 x10-3 + 1.18 x 10- + 8.20 x 10-4 + 3.94 x 10-4)
/ 4
=
3.92 x 10-3
/ 4
= 9.81 x 10-4
mol/L
Male after exercise average
Male AE =
(1.73 x10-3 + 1.59 x 10-3 + 1.13 x 10-3 + 8.36 x 10-4)
/ 4

4. Cordiel Brown
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=
5.29 x 10-3
/ 4
= 1.32 x 10-3
mol/L
Average difference in concentration for male
Male avg. Diff. =
(2.13 x10-4 + 4.10 x 10-4 + 3.12 x 10-4 + 4.43 x 10-4)
/ 4
=
1.378 x 10-3
/ 4
= 3.45 x 10-4
mol/L
Table showing Standard Deviation for Lactate concentrations for both males and females
Before Exercise After Exercise
Male +4.86 x10-4
+4.12 x 10-4
Female +1.57 x 10-3
+2.28 x10-4
Sample calculation:
Standard dev. For male before exercise
X X - (x - )2
1.53 x 10-3
5.49 x 10-4
3.01 x 10-7
1.18 x 10-3
1.99 x 10-4
3.90 x 10-8
3.94 x 10-4
-5.87 x 10-4
3.44 x 10-7
8.20 x 10-4
-1.61 x10-4
2.50 x 10-8
∑=7.09 x 10-7
S = √7.09 x 10-7
/ 4 – 1
S = √7.09 x 10-7
/ 3
= √2.36 x 10-7
= 4.86 x 10-4
Standard dev. For male after exercise

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X X - (x - )2
1.73 x 10-3
4.10 x 10-4
1.68 x 10-7
1.59 x 10-3
2.70 x 10-4
7.20 x 10-8
1.13 x 10-3
-1.90 x 10-4
3.60 x 10-8
8.36 x 10-4
-4.84 x10-4
2.34 x 10-7
∑=5.10 x 10-7
S = √5.10 x 10-7
/ 4 – 1
S = √5.10 x 10-7
/ 3
= √1.70x 10-7
= 4.12 x 10-4
Table showing Standard errors for Lactate concentrations for both male and females
Before Exercise After Exercise
Male 2.43 x 10-4
2.06 x 10-4
Female 9.08 x 10-4
1.32 x 10-4
Sample calculation
Male before exercise
S.E =
4.86 x 10-4
/ √4
=
4.86 x 10-4
/ 2
= 2.43 x 10-4
Male after exercise
S.E =
4.12 x 10-4
/ √4
=
4.12 x 10-4
/ 2

6. Cordiel Brown
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= 2.06 x 10-4
Answers to questions:
3. Glycolysis produces 2 ATP and 2 NADH molecules. NAD+ is a glycolytic intermediate which is
responsible for the oxidation of glyceraldehydes-3-phosphate. Reduction of the oxidizing
equivalent prohibits the oxidation and glycolysis is stopped. Therefore it is important for
cytoplasmic NADH is to be re-oxidized.
4. The fate of blood lactate produced by exercise varies according to the tissue type which picks it
up. For instance, with cardiac muscle cells, lactate is oxidised to pyruvate and enters the Krebs
cycle to yield energy and biosynthetic products. However, the lactate picked up by the liver is
converted to glucose by gluconeogenesis.
5. Erythrocytes also produce L-lactate from glucose because they lack mitochondria. These
organelles need energy to maintain membrane integrity and produce energy anaerobically by
connecting glucose to lactate.
6. The physiological factors that determine the rate of production of lactic acid in different
individuals doing the same exercise are age, sex, fitness, cardiac output and general health. In
fitness, if the lactate threshold is reached after low intensity exercise, it usually means that
there is a problem with the oxidative energy system in the muscles. The more exercise done the
better the body can manage the lactic acid build up. Cardiac output affects lactic acid because it
increases the rate of production in the body. There are some diseases which affect the general
health of people by altering normal lactic acid build up in the body, for example, hypertension.
This causes limited amounts of oxygen to reach the muscles during exercise. Therefore creating
anaerobic conditions which are favourable to lactic acid production causing an accumulation in
the blood as a result of liver disease. This causes liver disease because the liver is an important
part of the management of lactic acid.
Discussion: Seven individuals were tested in this experiment and were all determined to be fit as the
difference in their blood lactate concentration before and after exercise were less than 3.6 mM. The
females can be deduced to be fitter than the males as the average difference in blood lactate before

7. Cordiel Brown
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and after exercise was less (1.37 x 10-4
) whereas in the males it was more (3.45 x 10-4
). The variation
from the average differences was more in males than in females. The accepted range for normal
blood glucose while at rest is arterial lactate: 0.5-1.6 mmol/L ;venous lactate: 0.5-2.2 mmol/L and in
the experiment it is seen that all the participants except “R.R” are within the range whereas R.R is
below it with 0.4 mmol/L. the physiological factors which could have affected the blood lactate
values are discussed in the answer to question six (6) above. A source of error in the experiment
could be that the subjects could be on medications that affect lactate production another source of
error is that they could possibly have some unknown health conditions which would the applicability
of the obtained results. One precaution that was taken was the proper disposal of waste carried out
– for instance, tissue paper and gloves contaminated with blood in biohazardous waste, sharps and
needles in the appropriate collection container. Another precaution was that the antecubital fossa
was appropriately swabbed with alcohol before blood was withdrawn, for sterilization purposes and
to prevent contamination from sweat (which also contains lactate). Also New clean sterile needles
were used each time a sample of blood was taken.
Conclusion:The objective to determine the concentration of lactate in the blood of individuals (males)
before and after exercise was achieved. it can be concluded that the fitness of an individual is greatly
related to their before and after blood lactate concentration, with the fitter individuals having a smaller
difference between the two values.
References:
Guyton, Arthur C., Hall, John E. Textbook of Medical Physiology 9th
ed. Philadelphia: WB Saunders
Company 1996
http://en.wikipedia.org/wiki/Anaerobic_exercise