question: what is happening from a cardiovascular perspective when you get in shape?
comment: When you train a lot your muscles become much more efficient at producing energy and your heart adapts to higher levels of workload, making it easer for it to handle less stressful tasks. Basically any part of our body can adapt to stress as long as it is not too much to take care of in too short of a period of time.
passages: Athlete's heart should not be confused with bradycardia that occurs secondary to Relative energy deficiency in sport or Anorexia nervosa, which involve slowing of metabolic rate and sometimes shrinkage of the heart muscle and reduced heart volume.
  
  The medical history of the patient (endurance sports) and physical examination (bradycardia, and maybe a third or fourth heart sound), can give important hints.
  
  BULLET::::- ECG – typical findings in resting position are, for example, sinus bradycardia, atrioventricular block (primary and secondary) and right bundle branch block – all those findings normalize during exercise.
   Section::::Fatigue.:Other factors.
  
  The exercise fatigue has also been suggested to be effected by:
  
  BULLET::::- brain hyperthermia
  
  BULLET::::- glycogen depletion in brain cells
  
  BULLET::::- reactive oxygen species impairing skeletal muscle function
  
  BULLET::::- reduced level of glutamate secondary to uptake of ammonia in the brain
  
  BULLET::::- Fatigue in diaphragm and abdominal respiratory muscles limiting breathing
  
  BULLET::::- Impaired oxygen supply to muscles
  
  BULLET::::- Ammonia effects upon the brain
  
  BULLET::::- Serotonin pathways in the brain
  
  Section::::Cardiac biomarkers.
   Section::::Metabolic changes.:Other.
  
  BULLET::::- Plasma catecholamine concentrations increase 10-fold in whole body exercise.
  
  BULLET::::- Ammonia is produced by exercised skeletal muscles from ADP (the precursor of ATP) by purine nucleotide deamination and amino acid catabolism of myofibrils.
  
  BULLET::::- interleukin-6 (IL-6) increases in blood circulation due to its release from working skeletal muscles. This release is reduced if glucose is taken, suggesting it is related to energy depletion stresses.
   Understanding the relationship between cardiorespiratory fitness and other categories of conditioning requires a review of changes that occur with increased aerobic, or anaerobic capacity. As aerobic/anaerobic capacity increases, general metabolism rises, muscle metabolism is enhanced, haemoglobin rises, buffers in the bloodstream increase, venous return is improved, stroke volume is improved, and the blood bed becomes more able to adapt readily to varying demands. Each of these results of cardiovascular fitness/cardiorespiratory conditioning will have a direct positive effect on muscular endurance, and an indirect effect on strength and flexibility.
   BULLET::::- Echocardiography – differentiation between physiological and pathological increases of the heart's size is possible, especially by estimating the mass of the wall (not over 130 g/m) and its end diastolic diameter (not much less 60 mm) of the left ventricle.
  
  BULLET::::- X-ray examination of the chest may show increased heart size (mimicking other possible causes of enlargement).
  
  Section::::Clinical relevance.
   The primary function of the cardiovascular system is transport of oxygen: blood is the vehicle, oxygen is the cargo. The task of the healthy cardiovascular system is to provide adequate perfusion to all organs and to maintain a dynamic equilibrium between oxygen demand and oxygen delivery. In a healthy patient, his or her cardiovascular system always increases blood flow in response to increased oxygen demand. However, in a hemodynamically compromised patient, when the system is unable to satisfy increased oxygen demand, the blood flow to organs lower on the oxygen delivery priority list is reduced and these organs may, eventually, fail. Digestive disorders, male impotence, tiredness, sleepwalking, environmental temperature intolerance, etc. are classical examples of a low-flow-state, resulting in reduced blood flow to the gut, sexual organs, skeletal muscles, skin, etc.
   Cardiovascular drift
  
  Cardiovascular drift (CVD, CV) is the phenomenon where some cardiovascular responses begin a time dependent change, or "drift" after around 10 minutes of exercise in a warm or neutral environment without an increase in workload . It is characterised by decreases in mean arterial pressure and stroke volume and a parallel increase in heart rate.
   BULLET::::6. Kemi OJ, Høydal MA, Macquaide N, Haram PM, Koch LG, Britton SL, Ellingsen Ø, Smith GL, Wisløff U. The effect of exercise training on transverse tubules in normal, remodeled, and reverse remodeled hearts. J Cell Physiol 2011, 226: 2235–2243.
  
  BULLET::::7. Aspenes ST, Nilsen TI, Skaug EA, Bertheussen GF, Ellingsen Ø, Vatten L, Wisløff U. Peak oxygen uptake and cardiovascular risk factors in 4,631 healthy women and men. Med Sci Sports Exerc 2011, 43: 1465–1473.
  
  BULLET::::8. Ellingsen Ø. Energy at Heart: matching demand with production. Cardiovasc Res 2011, 90: 7–8.
   BULLET::::- Calf raise (i)
  
  BULLET::::- Pectorals (chest)
  
  BULLET::::- Bench press (c)
  
  BULLET::::- Chest fly (i)
  
  BULLET::::- Dips
  
  BULLET::::- Machine fly (i)
  
  BULLET::::- Push-up (c)
  
  BULLET::::- Lats and trapezius (back)
  
  BULLET::::- Bent-over row (c)
  
  BULLET::::- Chin-up (c)
  
  BULLET::::- Pulldown (c)
  
  BULLET::::- Pullup (c)
  
  BULLET::::- Seated row (c)
  
  BULLET::::- Shoulder shrug (i)
  
  BULLET::::- Supine row (c)
  
  BULLET::::- Deltoids (shoulders)
  
  BULLET::::- Front raise (i)
  
  BULLET::::- Head stand into Handstand push-up (c)
  
  BULLET::::- Lateral raise (i)
  
  BULLET::::- Military press (c)
  
  BULLET::::- Rear delt raise (i)
  
  BULLET::::- Shoulder press (c)
  
  BULLET::::- Upright row (c)
  
  BULLET::::- Biceps (front of arms)
  
  BULLET::::- Biceps curl (i)
   BULLET::::- Cerny F., Burton H., "Exercise physiology for health care professionals", Human Kinetics, 2001
  
  BULLET::::- Kounalakis S., Nassis G., Koskolou M., Geladas N., "The role of active muscle mass on exercise-induced cardiovascular drift", Journal of Sports Science and Medicine, Sept, 2008
  
  BULLET::::- Maher, Maurice. "Cardiac Drift and Ironman Performance." Multisport Solutions. N.p., 24 Aug. 2012. Web. 11 Dec. 2013.
  
  BULLET::::- Coyle EF, González-Alonso J. Cardiovascular drift during prolonged exercise: new perspectives. Exerc Sport Sci Rev. 2001 Apr;29(2):88-92. Review. PubMed .
   BULLET::::- Pull ups with a supinated grip
  
  BULLET::::- Triceps (back of arms)
  
  BULLET::::- Close-grip bench press (c)
  
  BULLET::::- Dip (c)
  
  BULLET::::- Pushdown (i)
  
  BULLET::::- Triceps extension (i)
  
  BULLET::::- Forearms
  
  BULLET::::- Wrist curl (i)
  
  BULLET::::- Wrist extension (i)
  
  BULLET::::- Abdomen and obliques (belly)
  
  BULLET::::- Crunch (i)
  
  BULLET::::- Leg raise (c)
  
  BULLET::::- Russian twist (c)
  
  BULLET::::- Sit-up (c)
  
  BULLET::::- Lower back
  
  BULLET::::- Deadlift (c)
  
  BULLET::::- Good-morning (c)
  
  BULLET::::- Hyperextension (c)
  
  BULLET::::- Pelvis
  
  BULLET::::- Vaginal weightlifting
  
  BULLET::::- Extended length conditioning
  
  Section::::Types of exercise.:Calisthenics.
  
  Calisthenics
  
  BULLET::::- Abdominal exercise
  
  BULLET::::- Calf-raises
  
  BULLET::::- Crunches
  
  BULLET::::- Dips
  
  BULLET::::- Hyperextensions
  
  BULLET::::- Jumping jacks
  
  BULLET::::- Leg raises
  
  BULLET::::- Lunges
   BULLET::::- Reduced perfusion of skeletal muscle causes atrophy of the muscle fibers. This can result in weakness, increased fatiguability and decreased peak strength – all contributing to exercise intolerance.
   While the exact mechanism of myofilament alteration in response to exercise is still being studied in mammals, some interesting clues have been revealed in Thoroughbred race horses. Researchers studied the presence of mRNA in skeletal muscle of horses at three distinct times; immediately before training, immediately after training, and four hours after training. They reported statistically significant differences in mRNA for genes specific to production of actin. This study provides evidence of the mechanisms for both immediate and delayed myofilament response to exercise at the molecular level.
   Vigorous physical activity (such as exercise or hard labor) increases the body's demand for oxygen. The first-line physiologic response to this demand is an increase in heart rate, breathing rate, and depth of breathing.
   BULLET::::- Hinkle, J. Scott. "School Children and Fitness: Aerobics for Life". Ann Arbor, MI: ERIC
  
  BULLET::::- Clearinghouse on Counseling and Personnel Services.
  
  BULLET::::- Aberg MA, Pedersen NL, Torén K, Svartengren M, Bäckstrand B, Johnsson T, Cooper-Kuhn CM, Aberg ND, Nilsson M, & Kuhn HG. (2009) Cardiovascular fitness is associated with cognition in young adulthood. Proceedings of the National Academy of Sciences of the United States of America.
  
  BULLET::::- Guiney, Hayley & Machado, Liana. Benefits of regular exercise for executive functioning in healthy populations. Psychon. Bull. Rev. 2013.
   Alternatively, in order to find the efficiency of the lungs in replenishing blood oxygen levels, the a-vO diff may instead be taken by comparing blood from the pulmonary artery and the pulmonary vein; in this case a negative value for a-vO diff would be obtained as the oxygen content of the blood would have increased.
  
  Section::::Impacts of exercise.
  
  Physical exercise leads to an increase in the arteriovenous oxygen difference in all individuals. As exercise intensities increase, the muscles increase the amount of oxygen they extract from the blood, and this therefore results in further increases in a-vO diff.
   BULLET::::- "Changes in ventilatory threshold with exercise training in a sedentary population: the HERITAGE Family Study" National Center for Biotechnology Information. U.S. National Library of Medicine, n.d. Web. 03 Nov. 2014.
  
  BULLET::::- "Result Filters." National Center for Biotechnology Information. U.S. National Library of Medicine, n.d. Web. 03 Nov. 2014.
  
  BULLET::::- "Ventilatory Threshold." TheFreeDictionary.com. N.p., n.d. Web. 03 Nov. 2014.
  
  BULLET::::- Fitzgerald, Jason. “ VO2 Max Testing and Ventilatory Threshold: Endurance Testing for Runners.” Strength Running. 25, July 2010. Web. 8, August 2010.
  
  BULLET::::- "VO2 Max, Aerobic Power & Maximal Oxygen Uptake." Sports Fitness Advisor.
   BULLET::::- Cor pulmonale – Untreated cor pulmonale can cause right heart failure from chronic pulmonary hypertrophy.
  
  BULLET::::- Ventricular hypertrophy – Hypertrophy of the ventricle. Thickening of the myocardium (i.e., hypertrophy) can be physiological (a normal response) or pathological. An example of physiological hypertrophy is the result of significant athletic training (athletic heart syndrome).
   BULLET::::- Ultimate Frisbee (especially during impact from laying out)
  
  BULLET::::- Ballet
  
  BULLET::::- Muay Thai
  
  Although this condition can be caused by repetitive trauma to the lumbar spine in strenuous sports, other risk factors can also predispose individuals to spondylolsis. Males are more commonly affected by spondylolysis than females. In one study looking at youth athletes, it was found that the mean age of individuals with spondylolisthesis was 20 years of age. Spondylolysis also runs in families suggesting a hereditary component such as a predisposition to weaker vertebrae.
  
  Section::::Pathophysiology.
   Prolonged exercise such as marathons can increase cardiac biomarkers such as troponin, B-type natriuretic peptide (BNP), and ischemia-modified (aka MI) albumin. This can be misinterpreted by medical personnel as signs of myocardial infarction, or cardiac dysfunction. In these clinical conditions, such cardiac biomarkers are produced by irreversible injury of muscles. In contrast, the processes that create them after strenuous exertion in endurance sports are reversible, with their levels returning to normal within 24-hours (further research, however, is still needed).
  
  Section::::Human adaptations.
   The heart becomes enlarged, or hypertrophic, due to intense cardiovascular workouts, creating an increase in stroke volume, an enlarged left ventricle (and right ventricle), and a decrease in resting pulse along with irregular rhythms. The wall of the left ventricle increases in size by about 15–20% of its normal capacity. No decrease of the diastolic function of the left ventricle occurs. The athlete may also experience an irregular heartbeat and a resting pulse rate between 40 and 60 beats per minute (bradycardia).
   Bradycardia is not necessarily problematic. People who regularly practice sports may have sinus bradycardia, because their trained hearts can pump enough blood in each contraction to allow a low resting heart rate. Sinus bradycardia can also be an adaptive advantage; for example, diving seals may have a heart rate as low as 12 beats per minute, helping them to conserve oxygen during long dives.
  
  Sinus bradycardia is a common condition found in both healthy individuals and those who are considered well conditioned athletes.
   BULLET::::- Aortic body and carotid body
  
  BULLET::::- Autoregulation
  
  BULLET::::- Cerebral Autoregulation
  
  Section::::Regulation of blood pressure.:Hemodynamics.
  
  Under most circumstances, the body attempts to maintain a steady mean arterial pressure.
  
  When there is a major and immediate decrease (such as that due to hemorrhage or standing up), the body can increase the following:
  
  BULLET::::- Heart
  
  BULLET::::- Total peripheral resistance (primarily due to vasoconstriction of arteries)
  
  BULLET::::- Inotropic state
  
  In turn, this can have a significant impact upon several other variables:
  
  BULLET::::- Stroke volume
  
  BULLET::::- Cardiac output
  
  BULLET::::- Pressure
  
  BULLET::::- Pulse pressure (systolic pressure - diastolic pressure)
   BULLET::::- Intense (high VO max) or prolonged aerobic exercise transiently increases cortisol levels to increase gluconeogenesis and maintain blood glucose; however, cortisol declines to normal levels after eating (i.e., restoring a neutral energy balance)
  
  BULLET::::- The Val/Val variation of the "BDNF" gene in men and the Val/Met variation in women are associated with increased salivary cortisol in a stressful situation.
  
  BULLET::::- Severe trauma or stressful events can elevate cortisol levels in the blood for prolonged periods.
  
  BULLET::::- Subcutaneous adipose tissue regenerates cortisol from cortisone by the enzyme 11-beta HSD1.
  
  BULLET::::- Anorexia nervosa may be associated with increased cortisol levels.
   Section::::Metabolic changes.:Plasma glucose.
  