Physiological processes during the year

Whether it's a simple physical or intense exercise, the body is subject to physical adaptations for (increased energy expenditure) and after exercise (restoration of glycogen reserves mainly activity (1 ), repair of damaged tissue and, if the activity is intense and practiced regularly, increase in muscle mass). More specifically, when an activity requires physical exertion physiological aspects will be changed, these mainly concern the respiratory and circulatory functions:Cardiac output increases due to an amplification of the heart rate (how many times per minute the heart contracts, usually at rest is 72 beats per minute) and the volume ejected during each contraction.Increased respiratory rate: number of breaths (inhalation and exhalation) per minute. At rest it is about 12 cycles per minute.Eventually elevation of lactic acid: lactic acid is produced when the activity exceeds a certain intensity and requires the production of energy anaerobically (see below). Production has the effect of reducing the pH in the muscles.

These physiological processes are the result of changes occurring at the cellular level: muscle contraction. When an increase in physical activity, the muscles will require higher energy inputs to allow their contractions. The only form useable by the power cell, including muscle cell is adenosine triphosphate (ATP). ATP is generated from the breakdown of glucose and this can be done in three metabolic pathways (channels) depending on the amount of energy (and therefore the intensity and duration of exercise). The aerobic pathway is taken during activities rather low intensity and long duration. The manner in which glucose is used to produce ATP requires oxygen. Analactique the anaerobic pathway suitable for intense exercise of short duration. The path used to produce ATP does not require oxygen and no lactic acid is generated. Finally, during intense activities lasting energy is synthesized by anaerobic fermentation. In this case, oxygen is still used, but the lactic acid is produced.

And during exercise, oxygen consumption, also known volume of oxygen (VO2) increases with the intensity of physical activity until a threshold for which this volume does not increase despite the increase the workload. This volume corresponds to the threshold VO2max. Beyond this value, energy is produced anaerobically, together with the lactic acid synthesis.

 Depending on the type of activity burned nutrients will vary. Different factors determine which category of "fuel" the muscle will use during the year: the intensity of physical activity, its duration, the training of the individual and his power.

Intensity: During a high intensity exercise, fatty acids can not be used because their degradation is too slow to allow the muscles to get the energy they need. In addition, fatty acids provide less ATP per liter of oxygen consumed as glucose.

Duration: More activity will be long lasting, plus the contribution of fatty acids as an energy source will be important. However, fatty acids can not be metabolized if carbohydrates are available. So, muscle glycogen and blood glucose are limiting factors.

 Thus, for intense efforts of very short duration (less than ten seconds) phosphocreatine (2) muscle is the main source of energy, if this effort is maintained muscle glycogen will be used with lactate production. Will involve preferentially lipids (fatty acids from adipose tissue and muscle triglycerides) of moderate effort activities.

Effect of training: The time during which an athlete can oxidize fatty acids to produce ATP depends on the intensity of exercise but also his physical condition. Training increases the capacity of the individual to metabolize fatty acids. Other physiological adaptations are the result of continuous trainings, as the body adapts to the intensity level, these include the resting heart rate, blood pressure, rate of gas exchange (VO2max transmission capacity and uptake of oxygen), the volume of blood ejected during each cardiac contraction (stroke volume), the muscle infarction, lung capacity, and hemoglobin. In other words, the training improves respiratory and cardiovascular functions and sports and its metabolic efficiency (it is more efficient to synthesize energy). On the lactic acid a driven person will have a higher than that of a non-driven threshold, meaning it will be able to work harder for longer before his muscles sour. So a person or not unaccustomed to practice a sport quickly reach its lactic threshold which will cause muscle fatigue causing it to decrease the intensity of effort or even cease operations.Food: If the athlete has a diet rich in carbohydrates muscle glycogen is used as a source of ATP. And it consumes a lot of fat they used instead of fuel. But poor resources glycogen limit endurance and athletic ability to perform high intensity exercises. The priority of the type of substrate used during physical exertion is as follows:Alcohol: Alcohol is a toxin. Get rid as soon as possible of this toxin becomes the top priority for the organization.Protein: obtaining ATP from proteins is faster than going dip into glycogen. However, this metabolism occurs only for physical activity for long periods.Carbohydrates: the beginning of the year (blood glucose and muscle glycogen).Fat: when exercise continues (blood fatty acids and muscle triglycerides). However, the ability of the body to burn fat depends on the amount of insulin (and therefore the amount of glucose) in the blood low, use of fat or high carbohydrate utilization. In practice however the carbohydrates and fats are the main energy substrates. If exercise is performed immediately after a meal, blood glucose will be the first energy substrate. When it runs out the body uses its reserves: glycogen is stored in the liver and muscles and fat in the form of triglycerides stored in adipose tissue. It is however not recommended to exercise immediately after eating and especially the meal was hearty. During digestion the blood is mobilized in the digestive tract, skeletal muscles are less supplied with blood, thus promoting the onset of cramps. In addition, the movement of food in the stomach due to exercise can cause discomfort and digestion can be compromised. Hiking after a meal is possible but it is best to wait one to two hours for more intense activities.