Question

fatigue is a sports activity due to
1. lack of physical activity
2.formation of lactic acid 3. Mental tension 4.improper playing surface​

Answer 1

Answer:Fatigue is caused due to the lack of oxygen in muscles.The formation of lactic acid results in muscle cramp.The formation of lactic acid is due to anaerobic respiration.

Hence,the answer for your question is-

2.Formation of lactic acid.

Answer 2

Explanation:

Abstract

Muscle fatigue is a common complaint in clinical practice. In humans, muscle fatigue can be defined as exercise-induced decrease in the ability to produce force. Here, to provide a general understanding and describe potential therapies for muscle fatigue, we summarize studies on muscle fatigue, including topics such as the sequence of events observed during force production, in vivo fatigue-site evaluation techniques, diagnostic markers and non-specific but effective treatments.

Introduction

Fatigue is a common non-specific symptom experienced by many people and is associated with many health conditions. Often defined as an overwhelming sense of tiredness, lack of energy and feeling of exhaustion, fatigue relates to a difficulty in performing voluntary tasks.1 Fatigue accumulation, if not resolved, leads to overwork, chronic fatigue syndrome (CFS), overtraining syndrome, and even endocrine disorders, immunity dysfunction, organic diseases and a threat to human health.

There are many different fatigue classification methods. According to its duration, fatigue can be classified into acute fatigue and chronic fatigue. Acute fatigue can be quickly relieved by rest or life-style changes, whereas chronic fatigue is a condition defined as a persistent tiredness lasting >months that is not ameliorated by rest.2, 3, 4 Fatigue can also be classified as mental fatigue, which refers to the cognitive or perceptual aspects of fatigue, and physical fatigue, which refers to the performance of the motor system.1

Muscle fatigue is defined as a decrease in maximal force or power production in response to contractile activity.5 It can originate at different levels of the motor pathway and is usually divided into central and peripheral components. Peripheral fatigue is produced by changes at or distal to the neuromuscular junction. Central fatigue originates at the central nervous system (CNS), which decreases the neural drive to the muscle.5, 6 Muscle fatigue is a commonly experienced phenomenon that limits athletic performance and other strenuous or prolonged activity. It is also increases and restricts daily life under various pathological conditions, including neurological, muscular and cardiovascular disorders, as well as aging and frailty. This review primarily focuses on muscle fatigue, particularly during intense exercise, to provide a basic understanding and potential therapies for muscle fatigue.

Factors that affect muscle contraction and fatigue

The production of skeletal muscle force depends on contractile mechanisms, and failure at any of the sites upstream of the cross-bridges can contribute to the development of muscle fatigue, including nervous, ion, vascular and energy systems.7 Specifically, metabolic factors and fatigue reactants during the process of contraction, such as hydrogen (H+) ions, lactate, inorganic phosphate (Pi), reactive oxygen species (ROS), heat shock protein (HSP) and orosomucoid (ORM), also affect muscle fatigue.

Neural contributions

Central neurotransmitters, especially 5-HT, DA and NA, play important role during whole-body exercise and fatigue. 5-HT produces a negative effect, whereas methylphenidate, a DA-releasing enhancer and reuptake inhibitor, produces a positive effect in exercise performance.8 The so-called central fatigue hypothesis states that exercise induces changes in the concentrations of these neurotransmitters, and fatigue arises from changes within the CNS (or proximal to the neuromuscular junction). However, recent data have shown that drugs influencing the neurotransmitter systems scarcely perturb performance under normal ambient temperatures but significantly improve endurance under high ambient temperatures. For example, the NA reuptake inhibitor reboxetine and a dual DA/NA reuptake inhibitor, bupropion, have a negative effect9, 10, 11 on exercise performance under normal temperature. However, under heat, reboxetine decreases, whereas bupropion increases performance, thus suggesting that the thermoregulatory system may have an important influence on exercise performance.

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