Volume 6, Spring 2008 - Saddleback College

Fall 2007 Biology 3A Abstracts
Environmental Science & Technology, 36 (6): 1202-
1211.
Labadie, P., Cundy, A.B., Stone, K., Andrews, M.,
Valbonesi, S., and Hill, E.M. (2007). Evidence for the
Migration of Steroidal Estrogens through River Bed
Sediments. Environmental Science Technology, 41,
4299-4304.
Lai, K.M., Scrimshaw, M.D. and Lester, J.N. (2002).
The Effects of Natural and Synthetic Steroid Estrogens
in Relation to their Environmental Occurrence. Critical
Reviews in Toxicology, 32 (2): 113-132.
Oiverira, R.F., McGregor, P.K., Latruffe, C. (1998).
Know Thine Enemy: Fighting Fish Gather Information
from Observing Conspecific Interactions. Proceedings:
Biological Science, 265 (1401): 1045-1049.
Potera, C. (2000). Drugged Drinking Water.
Environmental Health Perspectives, 180 (10): 108-
110.
Quintana, J.B., Carpinteiro, J., Rodríguez, I., Lorenzo,
R.A., Carro, A.M., and Cela, R. (2004). Determination
of Natural and Synthetic Estrogens in Water by Gas
Chromatography with Mass Spectrometric Detection.
Journal of Chromatography A, 1024, 177-185.
Effects of Increased Levels of Lactate on Cognitive Ability
Kevin Murray and David Stapleton
Department of Biological Sciences
Saddleback College
Mission Viejo, California USA
This study investigates the effect of lactate on cognitive ability, in the form of memory
recall. Sports and competition often hinge on the ability of a participant to make good
decisions. This is especially true near the end of a game or competition when the game is
on the line. Often near the end of a physical competition the participants become fatigued
and have elevated levels of lactate, and this fatigue can lead to poor decision making. This
study reproduced fatigue by inducing higher levels of lactate, due to strenuous physical
exercise on a stationary bike. Higher levels of lactate were expected to create a lesser
cognitive ability; in this case the cognitive ability was the outcome of a memory recall test.
Although there were some differences in cognitive abilities at different lactate levels, this
study found there was no significant difference in the average cognitive ability between
baseline and elevated levels of lactate for the ten participating subjects.
Introduction
Competitive sports, team and individual, often
hinge on the decision making of the participants. Early
on in the competition individuals are at peak levels
physically and mentally; however, this may not hold
true for the later phases as individuals tire (Fleury and
Bard, 1987). The physical effects of extended exercise
can be readily seen and measured, but differentiating
the decision making capability remains somewhat
nebulous. This decision making ability at later stages of
a competition can be critical, making the difference
between winning or losing.
Extended exercise pushes individuals into the
oxygen starved levels of anaerobic activity, generating
increasing levels of lactate and depleting levels of
available glucose. While the body can generate
supplies of glucose for the brain through
gluconeogenesis, disposing of some of the excess
lactate, there are still increased levels in the blood
stream. This excess lactate flows across the blood
brain barrier (Nemoto and Severinghaus, 1974) and
may have an affect on the decision making capability
of individuals. There is also evidence of extracellular
lactate in the brain in studies done on rats (De Bruin et
al., 1990). This lactate was the result of stress,
primarily stress brought on by exercise. Further
evidence supports the presence of increased lactate in
the brain during cognitive stimulation (Urrila et al.,
2003).
There is some evidence to point to an adverse
effect from lactate in the brain (Bakker, et al.,
2004)(Kaufmann, et al. 2004)(Weiskopf, et al., 2002),
as well as evidence that shows that the presence of
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Saddleback Journal of Biology
Spring 2008