Physiological Changes in College Students while Taking Exams
Authors: Novak Mackenzie , Harris Abigail E. , Keuler Sydney A. , Rogatzki Matthew J. 
Published: November 2023

Cognitive improvements caused by exercise are attributed to increases in plasma catecholamine and endorphin levels. Although largely ignored in studies on cognitive function, increases in blood lactate (La−) levels may be beneficial as evidence suggests that the brain prefers lactate to glucose as a metabolic fuel. Although there is a growing body of research on the effect exercise has on cognitive performance there is little research investigating physiological variables during cognitive assessment without prior exercise.

Objective

To determine if there are physiological differences that determine cognitive performance in the absence of prior exercise.

Methods

Resting La− was measured in capillary blood of 22 students before and after three exams and one lecture using a portable lactate analyzer. Heart rate was monitored during each exam and lecture using HR monitors. Students were asked how much time he or she studied before each exam and how difficult the exam was to determine if study time and exam difficulty affected exam score. The difficulty of each exam was based on a scale of 1 – 10 with 10 being the most difficult exam the student has ever taken. Following data collection exam scores were grouped into lowest, middle, and highest percentage with the lecture acting as the control. Diet before each trial and distance walked to the classroom were controlled for every student.

Results

The scores of all exams were significantly different (Lowest score: 70.58 % ± 11.37; Middle score: 78.91 % ± 8.02; Highest score: 86.48 % ± 8.10, p < 0.01). Change in La− concentration from pre‐exam to post‐exam was significantly different between the exam with the lowest score (−0.35 mM ± 0.99), the exam with the middle score (0.21 mM ± 0.54, p = 0.01), and the exam with the highest score (−0.25 mM ± 0.82, p = 0.02). There was no significant difference in La− concentration between the lowest and highest scoring exam or among the lecture day (−0.23 mM ± 1.27) and any of the exams (p > 0.05). Average HR was not different among any of the exams or the lecture day (Lowest score: 83.25 bpm ± 15.91; Middle score: 80.88 bpm ± 12.52; Highest score: 81.35 bpm ± 14.47; Lecture: 82.36 bpm ± 13.61), p > 0.05. The exam in which students scored the highest was significantly less difficult (4.7 ± 1.36) than the middle (5.98 ± 0.98, p < 0.01) and lowest scoring exam (5.93 ± 0.97, p < 0.01), with no significant difference between the difficulty of the middle and lowest scoring exam, p = 0.87. Study time was not significantly different among exams (Lowest score: 5.1 hrs. ± 3.9; Middle score: 5.4 hrs. ± 6.0; Highest score: 5.2 hrs. ± 4.5), p > 0.05.

Conclusions

Lactate levels decreased during exams where students scored the highest and lowest but increased during the exam in which they scored in the middle. This suggests similar La− metabolism when a student is struggling or succeeding during an exam. The highest exam score being rated as the lowest difficulty indicates that students score better on exams they perceive as less difficult. Study time was similar across all exams indicating that exam performance is not always dependent on the time a student spends studying. Average HR was the same across all conditions indicating that catecholamines may not affect cognitive performance. Overall, these results suggest that La− metabolism and exam difficulty play a larger role in exam performance than study time or HR.

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