 Exercise is a huge stressor for the body but body is quite equipped to handle this kind of stress. Let us see how body responds to exercise. First of all let us see what is the difference in performance of exercise in case of male and a female. Actually the muscle in case of a male and a female can produce the same maximal force of contraction that is equivalent to 3 to 4 kg per centimeter square. So the basic difference between male and female depends on the muscle mass, how much amount of the muscle is present rather than the maximal force which can be generated by this muscle mass. So because the females have less muscle mass the maximal strength which can be generated in a female is less and why is it that the females have less muscle mass because of the hormones which are different in case of male and female. In fair there is testosterone which is basically causes increased protein synthesis and also there is a decrease in percentage body fat mass in males compared to that of female and why is it so it is because of the estrogen. So estrogen increases the percentage of body fat mass in females. Now whenever we are talking about exercise three things or three terms we should be aware of. One is the strength the maximum force which can be generated then there is power okay and then there is endurance. So let us see what all these three terms means. Strength here means as I told you that the force of contraction per centimeter square. So if muscle mass is more then the strength of contraction or the force generated by the muscle will be more fine. Now then what is power? Power is if we see formula wise is work done work done per unit time. So there is a component of time here and work done means there is force into distance and divided by time. So when we were talking of strength we took care only about force. Now when we are talking about power we are seeing that this force causes the movement of anything for how much distance and how fast or how slow it is being done. So that is per unit time. So this power is determined by many things it is determined by strength because the component of force is there right. It is also determined by rate of doing the work and this rate of doing the work in turn will be dependent on how your body is supplying the ATP to the muscles. If the ATP supply is very quick then the power will be more. But if the ATP supply is slower then the power will be less right. So we will see later on that what determines the power apart from the strength in the muscle. And finally there is endurance endurance is that how long how long any activity can be sustained. So this is basically dependent on the nutritive support of the muscle. So for example that how much glycogen is stored in the muscle right slowly slowly we will detail all these aspects that how these things the storage the delivery of ATP how it affects the exercise performance. Now obviously performing any exercise what we need is energy and what is the energy currency it is the ATP right. So what are the sources of this energy in muscle. So that comes in the muscle metabolic system let's move into it and discuss about the various muscle metabolic systems. So there are three fundamental sources of energy when we are considering the various muscle metabolic system one is the phosphogen system phosphogen system second is the glycogen lactic acid system and third is the aerobic system. Now this phosphogen system consists of two aspects one is stored ATP right. And then there is phospho creatine creatinine system phospho creatine creatine system okay. So this phospho creatinine is nothing it is basically creatine attached to a phosphate group and what is this ATP ATP is adenosine attached to three phosphates okay three phosphates are there and out of these three phosphate these two phosphates are high energy bonds. So when there will be cleavage of these bonds there will be release of lot of energy and how much energy it is it is 7300 calories per mole of ATP. So each bond each bond is releasing 7300 calories per mole of ATP. Now why we need to know about these three systems or how are these three systems different from each other. First of all the timing for which they last see this phosphogen system last very less the stored ATP actually it is only for three seconds so in within three seconds we can use all the ATP which is stored and in around total 8 to 10 seconds we can use all the creatine phosphate which is stored. So this system lasts only for approximately 10 seconds. So after the stored energy is used the glycogen lactic acid system comes into play when the glycogen which is stored is broken down into pyruvate and this pyruvate can either enter into the mitochondria and there will be this full oxidation of will occur and that will release lot of ATP's but the faster pathway is where this pyruvate is converted into lactate. Okay so this component only glycogen being converted into pyruvate releases four ATP molecules okay and if you see this pathway it will take a long time because lot of oxygen will be required and there will be lot of cycles however it can release more ATP much much more ATP. So in this what I am trying to tell you that this release of ATP is much faster rather than the conversion of pyruvate to carbon dioxide and water via the full glycolysis that will take much more time. However this glycogen lactic acid system can last only for 1.3 to 1.6 minutes okay if we have to continue exercise any further then the aerobic system must come into play and which can be indefinite depending on how much nutrients our body has. So basically here we have dealt with two concepts one how fast energy is being released by the system and two how long these systems are lasting right. So if you see what we said that this stored ATP and phosphocritin system last only for 8 to 10 seconds. So obviously this phosphogen system will not be sufficient for any endurance type of exercise like for marathon running right. However where we need short burst of power this phosphogen system is essential because it will release energy very very fast. Similarly glycogen lactic acid system last only for 1.3 to 1.6 minutes but it is faster than compared to aerobic system less fast than phosphogen system but faster than aerobic system. So it is approximately 2.5 times faster than the aerobic system and phosphogen system actually it is 5 times faster okay but remember that for continuing exercise for long duration we need aerobic system. So can you tell which of these muscle metabolic systems will be important for producing more power for the same person strength is there understanding muscle mass is there but which of these systems will generate with the same muscle mass more power it will be the phosphogen and glycogen lactic acid system. On the other hand for continuing the exercise for longer duration that is the endurance we need aerobic system. So that is how energy is being provided for the exercise but once the exercise is over there should be recovery as well because whatever is stored and used during the exercise should be replenished. So how that is being done that is understood by two concepts one is oxygen depth so we will see what is oxygen depth and the other is that the which diet will be best after the exercise. So let us see the concept of oxygen depth first what is oxygen depth. So here what we see on x axis we see time in minutes and on y axis we see rate of oxygen uptake in liters per minute. Now at rest the rate of oxygen uptake is how much it is approximately 250 ml per minute so let us draw a baseline this is the 250 ml per minute line which is the rate of oxygen uptake at rest. Now suppose at time point zero somebody starts exercising then what happens that there is increase in the rate of oxygen uptake even just at the start of exercise there is increase in the rate of oxygen uptake because the ventilation increases before itself right. So there is increase in the rate of the oxygen uptake and what happens that it increases maybe up to 18 to 20 times. So here we are seeing that it has increased to 4.5 liters that is basically 4500 ml and we said that 250 ml is the resting oxygen uptake so how much time it has increased let us see okay 90 so it has increased 18 times right according to this graph with the maximum exercise then as we stop the exercise say suppose here we stop the exercise what will happen that even after the stoppage of the exercise oxygen uptake will not suddenly come down like this what will happen that the oxygen uptake will remain more for some time and then for approximately 40 minutes it will remain above the baseline. It has not yet reached 250 ml per minute so okay we can understand that oxygen uptake has increased during the exercise so this is the part where exercise is being performed during the exercise oxygen uptake is increased but later on also it has not suddenly come down it is maintained more than resting level for some time so this is known as oxygen depth that means whatever has been used up that it is being returned now what is being returned actually oxygen there is a stored oxygen also and we have used the stored ATP that also is being returned so let us see the components of this oxygen depth in this graph see this portion it is known as a lactic oxygen depth okay and this flat portion that is known as lactic acid oxygen depth meaning what is this a lactic oxygen depth and lactic acid oxygen depth see normally I told you that there is ATP which is stored there is a phosphocrytine which is stored right and these have to be returned so how these will be formed obviously the nutrients which are there they should provide more and more ATP and there should be synthesis of high energy bonds in creatine that means a phosphate should bind with creatine and there should be regeneration of ATP so for that oxygen is required right secondly there is a stored oxygen also in body where is a stored oxygen you will wonder well first of all there is myoglobin in muscle to which oxygen is bound second at rest to how much oxygen is being used see to hemoglobin even in veins hemoglobin is 75 percent saturated isn't it though we are calling it deoxygenated hemoglobin but pressure of oxygen in veins is 40 millimeter mercury and there hemoglobin is 75 percent saturated so that is a reserve only right so during exercise more extraction of this oxygen takes place so that is also being utilized right then there is a storage in lungs as well how there is air in lungs right at FRC in residual volume there is dissolved oxygen when we start to breathing heavily there is obviously more ventilation but also there is increase in diffusion from the lungs into the pulmonary capillary so that is stored oxygen is also being used plus there is dissolved oxygen also understanding so there are many forms of direct stored oxygen we can call it as reserve oxygen isn't it so all this has to be restored so both of these combined form the alactic oxygen depth in this stored oxygen is approximately 2 liters okay and the oxygen required for regeneration of phosphocrytine ATP that is approximately 9.5 liters so alactic oxygen depth comes to 11.5 liters fine now what is lactic acid oxygen depth well we said in glycogen lactic acid system glycogen is being converted to pyruvic acid and this pyruvic acid very fast gets converted to lactic acid the oxygen required for conversion of lactic acid back to pyruvic acid okay pyruvic acid and this pyruvic acid again enters the oxidative metabolism here oxygen is required okay so for the removal of the lactic acid whatever extra oxygen is required that is the lactic acid depth and you see that because of this even when the exercise is stopped oxygen uptake is much more than that of the rest so that is one type of restoration of the stores also we need to restore the amount of the glycogen which has been used during exercise the stored glycogen has been used so we need to restore it how to restore it obviously the person should have proper diet after the exercise so what kind of diet helps in restoration well the person can take either high carbohydrate diet okay or he can take a mixed diet with the carbohydrate as well as fat or the person can take a high fat diet now it has been seen that with high carbohydrate diet it takes minimum of two days for restoration of the stored glycogen okay but with the mixed diet and high fat diet it takes many more days so that is why athletes are recommended high carbohydrate diet at least two days after any sports even so that whatever depleted glycogen is there it can be restored within two days and if you have seen sports events then suppose there are multiple teams so generally it is that that if one team has a match today then only after two days their next match is kept so that their nutrition is restored otherwise their performance is definitely is bound to decline there is another implication of this that when suggesting the athletes that how their behavior should be before the exercise obviously they should not undergo any strenuous exercise at least two days before their main event otherwise there will be depletion on the stored glycogen and it cannot be depleted within like short period of time it needs at least two days okay fine see now before we were talking about the power and endurance we have different sports event in which in some sports even more power may be required which are very short duration while in others more endurance may be required very classical example for high endurance is our marathon runners and where maybe extreme power is required for very short duration is like 50 meter dash 100 meter dash so how is that these particular athletes carry out different types of exercise well in our body there are different types of muscles known as fast twitch muscles and slow twitch muscles so as the name indicates fast twitch and slow twitch fast means they will be providing very high power for very short duration of time and slow twitch means that they can carry on for longer duration so with the knowledge what we have discussed can you tell that what kind of metabolism will be more prominent in these types of muscles fast twitch means that they should release more ATP fast right so these fast twitch muscle fibers are large in diameter they are actually twice in diameter than that of the slow twitch why so that they can store more amount of ATP and phosphocrytine and also their phosphogen nactic acid system is two to three times more active than that of slow twitch muscles on the other hand slow twitch muscles how they will work they will have increased mitochondria because it is important for aerobic metabolism increase in mitochondria increase enzyme activity of mitochondria and there is increase in myoglobin so myoglobin can store more oxygen and they have increased capillaries also so they can supply blood flow continuously for oxygen supply so obviously these slow twitch muscles are for endurance exercise and it has been seen that athletes of various sports even have more propensity of different types of muscle fibers rather it is genetically determined so for example anybody who is a marathon runner will by birth have more slow twitch muscles and such a person cannot become a winner of 100 meter dash because for 100 meter dash more abundance of fast twitch muscles is required by the way these fast twitches slow twitch muscle fibers are also known as red and white muscle fibers slow twitch is the red muscle fiber red because obviously blood flow is more myoglobin is more so it is red fast twitches muscle fiber is also known as white muscle fiber or type 2 muscle fiber and red is the type 1 muscle fiber thanks for watching the video if you liked it do press the like button share the video with others and don't forget to subscribe to the channel physiology open thank you