Understanding Aerobic Exercise PDF

Understanding Aerobic Exercise Aerobic fitness is synonymous with endurance or stamina – partly inherited and part trained to persist……….. Those who pursue fitness earn more than the training effect, in fact earn the health benefits Start walking, as you increase your pace and sp...

Understanding Aerobic Exercise Aerobic fitness is synonymous with endurance or stamina – partly inherited and part trained to persist……….. Those who pursue fitness earn more than the training effect, in fact earn the health benefits Start walking, as you increase your pace and speed, effort becomes more uncomfortable and breathing labored Up to this point the exercise has been aerobic, “meaning the presence of oxygen”- energy has come from the oxidation of fat and carbohydrate. If intensity of exercise increases, the muscles make a transition to anaerobic, or non oxidative, energy production, which involves intense effort and accumulation of lactic acid in the muscles and blood. Lactic acid is both an energy carrier and a metabolic by- product of intense effort. Its accumulation is a sign that you are using energy faster than it can be produced aerobically 11/21/24 Rajbirsingh Rajcoomar 1  Understanding Aerobic Exercise Aerobic exercise can be defined as exercise below the point at which blood lactic acid level rise – the lactate threshold Fiber Types Humans have three main types of muscle fibers: 1. Slow-twitch ( slow oxidative, or SO) – efficient in the use of oxygen 2. A faster-contracting type that can work with oxygen or without(fast oxidative, or FOG) 3. A Fast-twitch fiber that can uses muscle glycogen for short intense contractions(fast glycolitic, or FG) As we go from walk to a jog to a run we recruit SO, FOG, then FG fibers to help us to go faster. Recruit too many FG fibers and the effort becomes anaerobic, the fibers produce lactic acid and we are forced to slow down or stop. 11/21/24 Rajbirsingh Rajcoomar 2  Understanding Aerobic Exercise The oxidation of abundant fat reserves during aerobic exercise ensures an adequate supply of energy for extended periods of effort. B Aerobic exercise can be sustained for several L minutesSOto many hours SPRINT FOGand can converse during the o 10 Anaerobic FG o aerobic exercise. d (Lactate) L 8 Threshold RUN a Aerobic ct 6 Threshold JOG a t 4 e 2 WALK m M 25 % 50 % 75 % 100 % Vo2 max 11/21/24 Rajbirsingh Rajcoomar 3  Understanding Aerobic Exercise EXERCISE INTENSITY Light Moderate Intense Example Walking Jogging Running exercise Metabolism Aerobic Aerobic Aerobic/ Anaerobic Energy Fat and CHO CHO and CHO and Fat Source Fat Heart Rate < 120 120 - 150 > 150 Breathing Easy Can talk Hard to talk easily Source: Brian Muscle Fiber SO FOG FG PhD J.Sharkey, Recuited 11/21/24 Rajbirsingh Rajcoomar Fitness and Health 4  Understanding Aerobic Exercise Aerobic fitness ca be defined as the maximal capacity to take in, transport and utilise oxygen Usually this test is measured in the laboratory; it defines the highest sustainable intensity of effort. The test requires a treadmill, along with a metabolic measurement system to measure oxygen, carbon dioxide and the volume of expired air. After a brief warm up, the individual wear a mouthpiece to direct the air into the analyser. The test involves a walk ( or run for the more fit) on the treadmill, which is programmed to increase grade every minute or two. Oxygen intake is computed each minute as the test toward maximal effort The test is terminated when the individual can no longer keep up with the treadmill. The highest level of oxygen attained is called the Vo2 max. 11/21/24 Rajbirsingh Rajcoomar 5  Understanding Aerobic Exercise Vo2 Max Test This test is suitable for a wide range of individuals, from sedentary to elite athletes ( test takes 8 to 12 minutes) The protocol allows the test to be tailored to the subject’s level of fitness and previous training Aerobic capacity is measured by the maximum amount of oxygen which can be consumed by the working muscles in one minute(Vo2 Max). Vo2 /body weight = relative Vo2 max i.e. amount of oxygen consumed per kilogram of body weight per minute - ml/kg/min This is a measure of aerobic fitness. If two individual have the same score in liters which one is fit? If one weighs 60 kg and the other 100 kg. In a footrace the one having the highest score would be better able to take in, transport and utilise oxygen in the working muscles. 11/21/24 Rajbirsingh Rajcoomar 6 Understanding Aerobic Exercise A comparison of Vo2 Max Subjects Age Men Women(ml/ (ml/kg/min) kg/min) Untrained 18-22 45 39 Active 18-22 50 43 Trained 18-22 57 53 Elite 18-22 70 63 World class 18-22 80+ 70+ Untrained 40-50 36 27 Active 40-50 46 39 Trained 40-50 52 44 Elite 40-50 60+ 50+ Source: Brian J.Sharkey, PhD 11/21/24 Rajbirsingh Rajcoomar Fitness and Health 7  Understanding Aerobic Exercise Lactate (anaerobic threshold) When exercise becomes very intense, more energy is produced anaerobically, lactic acid begins to accumulate in the blood and carbon dioxide production increases. This discomfort is a sign that you have stepped across the anaerobic threshold. The threshold defines the upper limit of sustainable aerobic exercise. Threshold measurements can be made during the Vo2 max test. Blood is drawn after each stage (percent grade) of the treadmill test and analysed in a lactate analyser. The lactate threshold may be defined as the point at which lactate production increases dramatically. During exercise perceived athletes learn to listen to the information their bodies provide 11/21/24 Rajbirsingh Rajcoomar 8  Understanding Aerobic Exercise Factors Influencing 1. Heredity It takes tremendous natural endowment and years of systematic training to achieve high-level endurance performances. We inherit many factors that are important to aerobic fitness - Maximal capacity of the respiratory and cardiovascular systems - A larger heart - That is more red cells and haemoglobin - A high percentage of slow oxidative and fast oxidative glycolytic muscle fibers - “Mitochondria, the energy-producing units of muscle and other cells are inherited from maternal side” Recent evidence indicates that the capacity of muscle to respond to training is also inherited and improvements range from 5 to over 30 % 11/21/24 Rajbirsingh Rajcoomar 9  Understanding Aerobic Exercise Factors Influencing 2. Training The potential to improve aerobic fitness with training is limited. Most studies reveal that improvement occurs to 20 to 25 % (more with loss of body fat). Only adolescents ca hope to improve much more than 30%. Consider the following: Two individuals, one with an untrained Vo2 max of 40 ml/kg x min and the second one with a score of 60 ml/kg x min ~ If each trains and gains a 25 % improvement in Vo2 max ? A. 40 x 25 % = 10 + 40 = 50 ml/kg x min B. 60 x 25 % = 15 + 60 = 75 ml/kg x min Training raises A. above the average for young men, whereas B. is elevated to the level of elite endurance athletes. Even in the untrained state B. has a higher Vo2 max than A. “Who ever said life was fair?” 11/21/24 Rajbirsingh Rajcoomar 10  Understanding Aerobic Exercise Factors Influencing 3. Gender Boys and girls differ little in aerobic fitness, but on then girls fall behind Young women average 10 to 20 % less in aerobic fitness compared to young men But highly trained young female athletes are only 10 % behind One reason for this difference may be hemoglobin, the oxygen carrying compound found in red blood cells ( 2 grams less than men), but still some women have higher values than male endurance athletes (Sharkey 1986) Other reasons may that Women : - are smaller and have less muscle mass - Have more body fat 11/21/24 Rajbirsingh Rajcoomar 11  Understanding Aerobic Exercise Factors Influencing 4. Age Aerobic fitness decreases by 8 to 10 % per decade for inactive individuals regardless of their initial level of fitness Active individuals can reduce this trend to 4 to 5 % and those engaged in fitness training can further cut this to 2 to 3 % 5. Body Fat Remember that fitness is calculated per unit of body weight, so if fat increases, aerobic fitness declines So the easiest way to maintain or even improve fitness is to get rid of excess fat 6. Activity What you do, day by day, year after year, shapes your health, vitality and quality of life 11/21/24 Rajbirsingh Rajcoomar 12  Understanding Aerobic Exercise Factors Influencing The effect of years of training can be lost in a mere 12 weeks with cessation of activity (Coyle, Hemmert, and Coggan 1986) Three weeks of complete bed rest may cause a fitness decline of 29%, or almost 10 % per week but the lost can easily be restored with regular activity ( saltin et al. 1968) Remember that: - Moderate activity leads to above-average fitness and substantial health benefits - Training leads to a higher level of fitness and extra health benefits - And systematic training helps you achieve your potential 11/21/24 Rajbirsingh Rajcoomar 13  Understanding Aerobic Exercise Aerobic Fitness Field tests 1. Walking Test The Rockport Walking Test Utilises the time of 1.6 Km and some personal information to estimate the Vo2 Max. Vo2 Max = 132.853 – ( 0.0769 x weight in Ibs) - ( 0.3877 x age in years) + (6.315 x 0 for female, 1 for male) – (3.2649 x time-min) – (0.1565 x HR at end of test) (kline et al. 1987) 11/21/24 Rajbirsingh Rajcoomar 14  Understanding Aerobic Exercise Aerobic Fitness Field tests 2. Running test A 2.4 Km running test that requires a near-maximal effort This test must be carried after 6 to 8 weeks of training People above the age of 45 should consider medical examination Before the test, a proper warming up is required 11/21/24 Rajbirsingh Rajcoomar 15  Altitude Ml/Kg x Min < 5,000 Ft – no adjustment 5,000 Ft – subtract 30 s 65 6,000 Ft – subtract 40 s 7,000 Ft – subtract 50 s F 60 8,000 Ft – subtract 60 s I t 55 n e 50 9:35 run = 55 s s fitness score 45 s c 40 o 11:40 run = 45 35 r fitness score e 30 14 run = 35 fitness score Balke 1963; Cooper 1968; 25 Sharkey 1997b; Daniels 1977, personal communication 16 15 14 13 12 11 10 9 Min 1.5 mile (2.4 Km) Aerobic 11/21/24 fitness test Rajbirsingh Rajcoomar 16