Aerobic Conditioning KIN 325
Aerobic Conditioning 1. Cardiovascular fitness: Definition The ability to continue in strenuous tasks involving large muscle groups for extended periods of time • Two major goals of aerobic conditioning: • To enhance the capacity of the cardiovascular system to deliver oxygen to the working muscles • To enhance the capacity of the “metabolic machinery” to utilize the oxygen that is delivered
2. ATP- the energy currency • quantity of ATP limited • ATP must be re-synthesized to provide continuous energy supply • Fastest method of re-synthesizing ATP is through the splitting of creatine phosphate (CP)
3.The energy systems a. ATP-CP system Can sustain all-out exercise for approximately 5-8 seconds
Additional source of energy required to re-synthesize ATP after ATP-CP system is no longer effective b. Anaerobic Glycolysis • only carbohydrate can reform ATP without the presence of oxygen • when glucose enters a cell to be used for energy it undergoes a series of chemical reactions liberating a net 2 mols ATP - Glycolysis • system relatively fast; will power all-out exercise lasting between 10-60 seconds
c. The Oxidative (Aerobic) System • Aerobic metabolism releases the remaining 95% of the energy from the glucose molecule - Krebs cycle • Also, fats and proteins are metabolized aerobically • Performance in activities lasting more than two minutes is affected by an individual’s capacity for aerobic ATP synthesis
4. Oxygen uptake during exercise First 3 minutes- steep rise then levels off once reached steady state – balance between energy required by the working muscles and the energy liberated by aerobic metabolism Trained person will reach steady state sooner than untrained person
Maximal Oxygen Uptake Maximal amount of oxygen that can be used at the cellular level to re-synthesize ATP
5. Lactic acid production • At 50-60% of VO2max, aerobic metabolic pathways cannot keep up with the total energy demand of the workload • Lactate threshold – point at which lactate production starts to exceed removal • Training enhances lactate tolerance
6. Adaptations with aerobic training • Increase in blood volume and hemoglobin • An increase in the number of functional capillaries • Increase in skeletal muscle myoglobin • Increase in heart size • Increase in maximum cardiac output (CO) measured in liters/min • CO =heart rate (HR) x stroke volume (SV) • Increase in stroke volume • At rest the heart ejects 5-6liters of blood per minute; this meets the energy demands of the body at rest
During exercise, blood output or cardiac output increases • Sedentary person = 20 liters per minute • Trained = 30 liters per minute • Highly trained = 35liters per minute • Decrease in submax. and resting heart rate • Increase in 02 extraction from the blood • Increase in size and # of mitochondria and associated aerobic system enzymes • V02max increases (5-40%) • Lactate threshold increases • Shorter recovery period • Reduction in both systolic and diastolic blood pressure • Reduction in LDL, increase in HDL • Increase in the muscle’s capacity to mobilize fat. Increase in fat-metabolizing enzymes.
7.Cardiovascular endurance assessments • The level of cardiovascular fitness is assessed by measuring or estimating VO2max • VO2max = The maximal amount of oxygen that a person can utilize per minute to re-synthesize ATP for biological work (ml/kg/min) 8. Cardiovascular exercise prescription • Follow FITT principle (Frequency, Intensity, Time, Type) • Frequency - Ideally 3-5times per week • Intensity - Improvement occurs when a person is working between 50-85% of VO2max
To determine cardiovascular range: 1. % of maximum heart rate (MHR) MHR = 220 – age Elevate HR between 70 – 90 % MHR 2. Karvonen formula - % of heart rate reserve • Heart rate reserve - the difference between the maximal heart rate and the resting heart rate MHR = 220 – age Take resting pulse (RHR) Heart rate reserve (HRR) = MHR – RHR
e.g., 85% training intensity = HRR x 0.85 + RHR % V02max %HRR % MaxHR 50 50 66 55 55 70 60 60 74 65 65 77 70 70 81 75 75 85 80 80 88 85 85 92 90 90 96
Time General recommendation is 20-60 minutes • Type The exercise must involve the major muscle groups and be rhythmic and continuous The more muscle mass involved during the exercise the greater the cardiovascular benefits Training Specificity Aerobic training improvement is specific to the mode of exercise Continuous vs Intermittent Training Some sports require intermittent bursts of very high intensity exercise - soccer for example.
9. Caloric cost of activity: • It is recommended to burn at least 300 kcals/session • 175 lb person walking at 3.5 mph consumes oxygen at approx. 1 liter/min. 1 liter 02 = 5kcals. Therefore, to burn 300 kcals have to walk for 300/5 = 60 mins • The increase in metabolic rate post-exercise can increase the caloric cost of the activity 15-50%.
Excessive post-exercise oxygen consumption (EPOC) • Restoration of ATP-CP stores • Restoration of oxygen stores in the blood • Elevated cardiovascular-respiratory function • Elevated hormonal levels • Elevated body temperature • Lactate removal EPOC is higher when you have prolonged, exhaustive exercise. In other words you burn more calories post-exercise
10.Warm up and cool down • Warm-up - reduces the risk of problems associated with strenuous exercise Reduces the number of EKG abnormalities (indicative of abnormal blood flow to the heart muscle) • A five minute cool-down should be done at the conclusion of exercise