Sports medicine pt.2 Flashcards
(35 cards)
How does the body produce energy?
Through the formation of ATP from ADP+phosphate, main source of energy and storage being glycogen and fats, which are activated to produce ATP
What source is used for ATP production?
Depends on the situation :
- ATP and Phosphocreatine in muscles are used in maximal power short-lasting activities, lasting only 6-8 seconds
- Anaerobic glycolysis which is activated after phosphocreatine storage is depleted, and is represented by the lactic anaerobic system, it lasts 40-60 seconds, as it is fast but no so efficient since glycolysis is not so good in anaerobic situations; this will lead to
production of lactic acid and, as a consequence, pain in muscles – even if the pain is in reality due to
the fact that lactic acid is a weak acid and with time free hydrogen accumulates giving tissue acidosis and so pain
- Aerobic glycolysis: Limited power long lasting energy (minutes to hours) is provided by fats, through beta oxidations and glycogen, through aerobic glycolysis (dependent on oxygen) and; it is very
long lasting but has limited power: the typical examples of use of this energy are during marathons or cycling races.
How much glycogen is stored in the body?
About 500g (400g in muscles and 100g in liver)
What is the anaerobic treshold?
- The point where the body switches from anaerobic to aerobic glycolysis
- The exercise intensity where the muscles start to use anaerobic glycolysis
- The exercise intensity when the balance of production and removal of blood lactate is equal.
What is the waste product of anaerobic glycolysis?
Lactate and hydrogen ions
What happens during lactate production in anaerobic glycolysis
- Lactate production at the end of anaerobic glycolysis is
not alone but with hydrogen ions - So you start to accumulate hydrogen ions which is being buffered by
bicarbonate. When you use bicarbonate in your body, you develop metabolic acidosis - At maximum exercise you start to develop metabolic acidosis. So the real reason you feel pain and start
wheezing like hell and need to stop is because of metabolic acidosis and this is the anaerobic threshold. - Don’t think that this is because of lactate since it is a weak acid, it is because of hydrogen ions being
buffered by bicarbonate (HCO3) - However blood lactate is a good thing to measure to see if your body is
going into metabolic acidosis
What are ways to measure lactate?
Two different ways:-
Direct- taking a blood sample.
- Indirect methods use derived parameters to find the same concept. You don’t directly measure lactate but
you look for other parameters that can suggest to you where the anaerobic threshold happens. You can use
respiratory gases or heart rate. You can do an analysis with face masks with oxygen inspired and CO2
expired.
How does our body increase O2 supply during exercise?
1.By increasing blood flow to muscles (main mechanism): from 3 to 70-75 ml x 100 g of muscle/minute (20-25 folds increase of blood flow to muscles);
2- 2-3 fold increase in O2 extraction from the blood (O_2A-V difference goes from 5 to 13 ml x 100ml of blood)
What type of CV changes are seen during exercise?
2 types: Acute and chronic
- the more active CV changes are
stimulated the more the CV system tries to adapt and be more efficient, leading to chronic CV changes that
will allow us to be more fit.
- All these mechanisms give you the chance to achieve maximal performance in the acute phase of the
exercise.
Maximum heart rate calculation
- Theoretical max heart rate= 220-age in years (formula most simple and used in the clinic)
- Another formula is Tanaka formula: 208 – 0.7 x age in year; it is more efficient for extreme ages
(very young or very old pts)
What is cardiac output determined by?
Stroke volume and heart rate
How does heart rate, stroke volume, and cardiac ouput differ between sedentary people and athletes?
- In sedentary people, the HR can raise about 3-fold when they exercise. The SV on other hand increases just a little. In the end, the CO increases just by 3-4-
fold.. - In athletes the numbers are different; The HR is lower and the SV are much
higher at rest. This happens since they have bigger hearts and so bigger SV, reaching the same CO at rest
with fewer beats - During exercise, their HR and SV
increase a lot, giving rise to an almost doubled CO respect to sedentary people after exercise.
Which variable, sv or hr, affects cardiac output more in sedentary vs activity CO?
HR since it increases much higher than sv
What are conditioning factors?
These are the factors that are most relevant to determine the impact of a physical activity on the body, more
specifically the CV system:
* Intensity (energetic demand)
* Kind of exercise (endurance, isometric, …)
* Posture, involved limbs, …
* Psychological factors;
* Environment (altitude, depth, temperature, humidity …)
How can intensity of exercise be measured?
It can be measured by calculating MET (Metabolic Equivalence of Tasks)
What is a MET?
1 MET stands for the energy used in resting conditions, and MET values
of different sports can be seen on the chart (Golf 4.5 METs, etc)
- It can be expressed as a direct indicator of O2 consumption
O2 consumption at rest
At rest every kg of a person uptakes 3.5 ml of oxygen per minute. 3.5ml x kg/min
What can the kind of exercise be divided into?
Through studies, scientists established classifications on all sports based on their effect on the body. These
are;
- Power/Explosive Strength activities,
- Mainly Anaerobic Activities (short, brief, strenuous)
- Mixed Aerobic/Anaerobic Activities (short, max involvement of both metabolisms)
- Mainly Aerobic Activities (endurance)
- Dexterity/Skill Activities (posture, neuromuscular coordination)
We can also divide exercise into isotonic and isometric exercies
Describe CV effects of skill/dexterity activities
- CV involvement is minimum.
- Chronic Heart changes are poor, increase of volume and of myocardial mass are minimal and are
similar to sedentary subjects.
Describe CV effects of power activities
- Typical chronic heart changes are not much increase in heart volume and huge increase of myocardial mass.
- Weightlifting, alpine skiing, and surfing are some of the sports that fall into this class.
Describe CV effects of mixed activities
- Mainly compromised by a variety of team sports like football or water polo.
- Of course, the CV involvement is not the same in football as it is in volleyball but generally, they are all classified by variable changes in peripheral vascular resistance and cardiac output.
- During a match, HR, PVR and CO vary a lot and in the chronic setting the CV changes for heart volume and myocardial mass vary for each sport.
Describe CV effects of aerobic/endurance activities
- CV changes include a high increase of heart volumes and a moderate increase in myocardial mass.
- In this class we have long distance running, triathlons, and rowing. Cycling is included in the mixed
section rather than this one because there are both aerobic and anaerobic elements present.
Isotonic exercises vs isometric exercises discription
- Isotonic exercises are dynamic, they imply movement of articulations, while isometric exercises do not imply movement of articulations
- More simply, isotonic means that during the exercise there is a continuous change of muscle fibre length, whereas the force stays regular. Isometric on the other hand is when the muscle fibre length is stable when the force applied changes
- We classify dynamic isotonic exercises as endurance exercises that are performed for a long time over long distances, on the other hand weightlifting is an isometric exercise.
What is VO2 max related to?
Directly related to oxygen and cardiac output
