Alzheimer's disease has been linked to mutations in proteins that participate in the genesis of amyloid peptides. Multiple studies have shown that these mutations can increase the production of AB42 generated by amyloid precursor protein. This increase can hasten the onset of Alzheimer's disease. Previous research has examined the effects of lactic acid on the frequency of the mutations related to Alzheimer's disease; as a result of lactic acid exposure, production of AB40 and AB42 peptides was increased. Although researchers concluded that these results were most likely not due to lactic acids interaction with the enzyme BACE1, it was still sustained that elevations of lactic acid levels could be a risk factor in the progression of Alzheimer's disease. Drawing from the results of this study, one could conclude that minimizing the exposure to lactic acid would prevent the development of these mutations and the progression of Alzheimer's disease. However, lactic acid is produced during physical activity, which has been shown to be therapeutic to Alzheimer's patients. Ideally, one could still maintain a level of activity while minimizing the effects of the subsequent lactic acid production. Thus, the purpose of this study is to explore the effects of lactic acid pH on muscle cells. Rattus norvegicus aorta (thoracic/ smooth muscle cells) were chosen as the subject of this study because research has found that rat smooth muscle cells are able to survive in cultures in varying levels of acidity. A different level of human activity was represented in various well plates by manipulating the lactic acid levels. One group of cultures was exposed to high concentrations of lactic acid for short intervals (representing short periods of high activity). Another experimental group of cultures was exposed to low concentrations of lactic acid for a longer interval (representing long periods of low activity). Control groups were also studied in which the pH of each well was not manipulated at all. Results showed that high levels of lactic acid over a shorter period of time had a more dramatic effect on the pH of the rat cells opposed to low levels of lactic acid for longer periods of time. While results varied slightly from trial to trial, analysis suggests that this error is insignificant, making the data itself valid. This implies that short periods of high activity have a more dramatic effect on cells as well as the rate of mutations correlated with Alzheimer's disease. However, qualitative observations suggest that muscle cells exposed to high levels of lactic acid over short periods of time grew quicker than the muscle cells exposed to low levels of lactic acid for more time. Therefore, the results suggest that muscle cells undergoing short periods of high stress as opposed to extended periods of gentle activity will regenerate better. However, with regards to Alzheimer's patients, longer periods of low activity are ideal, if the results of this study translate to humans.