Purpose: The purpose of this study was to examine the genetic basis underlying voluntary exercise. Monoamine oxidase A (MAO-A) is an enzyme that acts on monoamine neurotransmitters, such as dopamine, to cause inactivation. There are several polymorphisms in the promoter region of the MAO-A gene, and these variations change transcriptional activity and the amount of MAO-A produced, leading to alterations in available dopamine levels. Interestingly, polymorphisms in MAO-A have been associated recently with physical activity level. This study sought to determine whether there is an association between motivation to exercise, levels of voluntary physical activity, and MAO-A gene polymorphisms.
Methods: Seventy-one participants (age 18-24 years, 13 males & 58 females) completed the Behavioral Regulation in Exercise Questionnaire-2 (BREQ-2) to assess their motivation to exercise and the International Physical Activity Questionnaire (IPAQ) to assess their level of physical activity. DNA was collected and isolated from a cheek cell sample. The MAO-A genotype was identified using PCR with gene specific primers. MAO-A 3/3 and 4/4 genotype individuals were used for analysis.
Results: External motivation to exercise was significantly higher (p \u3c 0.01) in the high transcription 4/4 genotype (x̄=1.11 ± 0.8) compared to the low transcription 3/3 genotype (x̄= 0.39 ± 0.6). Internal motivation to exercise was not different between genotypes. Body mass index and weekly MET minutes estimated by IPAQ were also comparable between genotypes.
Conclusion: The results suggest a polymorphism in this monoamine pathway may play a role in increasing sensitivity to external factors that motivate individuals to exercise
