**Abstract**

Research so far indicates that gut microbiome and diet interactions influence obesity, diabetes, host immunity, and brain function. The ability of athletes to perform to optimum for a more extended time, as well as the ability to resist, withstand, recover from, and have immunity to fatigue, injury depends on the genetic factor, age, sex, training history, psychological factors, mode, intensity and frequency of training and their interactions with the external dietary components. However, recent evidence indicates that the gut microbiome may also potentially influence the development of endurance in response to the type and composition of the external diet, including several food supplements. Thus, the gut microbiome has become another target in the athlete's pursuit of optimal performance. This chapter discusses the effect of exercise on the gut microbiome, the interplay between dietary components and supplements on the gut microbiome, and its impact on endurance performance.

**Keywords:** Diet, Gut, Endurance

## **1. Introduction**

Endurance exercises can be defined as prolonged exercises like running, cycling, cross-county skiing, aerobics and swimming, often involving resistance [1]. Endurance exercises require systemic and muscle-based physiological and biochemical responses to complete the endurance activity [2]. The athletes expose their bodies beyond their physiological circumstances, which affect the homeostasis, overwhelming normal tissue function [3]. Prolonged physical exercise will force body to defend against the events that will result in the synthesis of proteins, releasing of hormone, changes in body fluid as well as metabolic balance [4]. In order to adapt toward the endurance exercise, an individual should improve his mechanical, neuromuscular, metabolic and contractile functions in muscle, rebalance of electrolytes and decrease in glycogen storage [5]. Furthermore, endurance exercise will cause muscle damage, alterations in intestinal permeability, systematic inflammation, immune response and oxidative stress in the athletes [6]. Excessive exercise will effect the blood flow, resulting in loss of fluids and electrolytes. The body will start synthesizing glucocorticoids and adrenaline hormones to re-establish homeostasis [7].

Human gut microbiota act as an endocrine organ and plays a significant role in energy harvesting, nutrient uptake, vitamin synthesis, modulation of inflammatory, host immune response etc. Several intrinsic and extrinsic factor effect the gut microbiota, which will lead to dysbiosis. Some factors include diet, lifestyle,

environment, antibiotic use, age and birth delivery route. Recent findings reported that exercise induced changes in gut microbiota, through mechanisms not wellunderstood results modifications in metabolism, physiology, immunity and behavior in host [8]. Dysbiosis depends on the intensity, types and timing of excessive exercise [9]. Human gut microbiota also influences muscle mass and aging of the body. Studies reported the reduction of microflora in gut microbiota having antiinflammatory and proanabolic effects [10]. To adapt to the excessive physical load and increased energy consumptions, individuals performing excessive exercise e.g. athletes, should balance gut microbiota composition, which can only be done by adopting good dietary habits and using sports nutritional supplements. Gut microbiota plays significant role in the wellbeing, health and sports performance in athletes [11]. This chapter, discusses the effect of exercise on the gut microbiome, the interplay between dietary components and supplements on the gut microbiome, and its impact on endurance performance.
