Alzheimer's disease (AD) is one of the most common forms of dementia, which cannot be cured at the moment. Therefore, researchers also look for the alternative approaches to its treatment. It is suggested that changes in human gut microbiome mediated by exercise could influence the development and progression of AD and a new term"muscle-gut-brain axis"is introduced. There is much evidence to support this assumption. The gut microbiology is closely related to a wide range of diseases of the nervous system and therefore any negative qualitative and quantitative changes in the composition of the gut microbiota can potentially contribute to the pathophysiology of AD. Research shows that the treatment of intestinal dysbiosis with probiotics/synbiotics/eubiotics can prevent or alleviate the symptoms of these chronic neurological diseases. Studies also point to the positive effects of movement on the health of seniors. A positive correlation can be found between cognitive functions and physical stress, both in the elderly and in AD patients. Even short-term interventions with a relatively low frequency seem to produce positive results, while physical activities can be performed by using relatively simple and cost-effective means. In addition, physical activity can significantly modulate gut microbiome. Thus, it can be concluded that physical activity in humans seems to correlate with gut microbiome, which can prevent the incidence and development of AD.

The microbiome in the gut is a diverse environment, housing the majority of our bacterial microbes. This microecosystem has a symbiotic relationship with the surrounding multicellular organism, and a balance and diversity of specific phyla of bacteria support general health. When gut bacteria diversity diminishes, there are systemic consequences, such as gastrointestinal and psychological distress. This pathway of communication is known as the microbiome-gut-brain axis. Interventions such as probiotic supplementation that influence microbiome also improve both gut and brain disorders. Recent evidence suggests that aerobic exercise improves the diversity and abundance of genera from the Firmcutes phylum, which may be the link between the positive effects of exercise on the gut and brain. The purpose of this review is to explain the complex communication pathway of the microbiome-gut-brain axis and further examine the role of exercise on influencing this communication highway.