The detrimental effects of having a poor cardiovascular fitness have been studied extensively and more information is constantly arising; All of the data shows use that we should put more focus into improving our cardiorespiratory fitness(CRF). Individual CRF is based on both factors that can be modified and factors that can not. Risk factors such as physical inactivity, smoking, obesity, and certain medical conditions can be changed to reduce the risk of having a low cardiorespiratory fitness, while risk factors such as age, gender, and genes/genotype can not be altered. The largest and most prominent risk factor to a poor CRF is physical inactivity, lack of exercise, and a sedentary lifestyle. It’s crucial to place an importance on maintaining or improving cardiorespiratory fitness by being active. The reason being that prolonged sedentary behaviors (those involving sitting or low levels of energy expenditure) increase an individual’s risk of numerous diseases and disorders, including obesity, hypertension, diabetes, cancer, heart disease, musculoskeletal and psychological disorders, and even premature death.
Guidelines state that moderate aerobic physical activity should take place for a minimum of 150 minutes throughout the week. At a vigorous activity intensity 75 minutes is the minimum recommendation, but any combination of the two intensities is okay. It’s important to hit these minimum recommendations because the risk of a depressed cardiorespiratory fitness increases as frequency of activity decreases. This phenomenon can be better explained in the dose-response relationship between physical activity and health, which conveys that being at the lowest baseline(sedentary) means you have the most room for benefit, however, moderately active and active individuals have a higher overall health compared to sedentary individuals. Lack of physical activity creates many physiological changes to to body that are negative. Without physical activity the heart can start to break down muscle tissue and become smaller in size. Decreases in the heart mass present additional problems such as a decreased left ventricular end diastolic volume, which is the amount of blood in the heart’s left ventricle just before the heart contracts, meaning there is less filling in ventricle. That also means that the stroke volume is decreased. The stroke volume is the amount of blood pumped from the left ventricle with each heartbeat. Over time as these changes in muscle strength, filling space, and blood volume become greater it may result in weakness or make it harder to complete everyday tasks.
Additionally, a decreased plasma volume transpires due to loss in plasma proteins and less water/ sodium retention. This creates a higher blood viscosity which is linked to decreased blood flow to active muscle, and decreased capillarization. Another physiological change in the body is an increase in total peripheral resistance. That means there is greater impedance in vessels because of an increase in LDL’s, total cholesterol, triglycerides, plague, and artery stiffness. Another physiological change is an increase in both subcutaneous and visceral body fat.
This is problematic because both heart rate and blood pressure increase which puts substantial cardiac stress on the body. Increases in blood volume, heart rate, stroke volume, blood viscosity, or peripheral resistance can increase blood pressure. High blood pressure is called hypertension and is not good for the body because it adds to the workload of your heart and arteries by making the heart pump faster and arteries carry blood under greater pressure. Ultimately, a poor cardiorespiratory fitness leads to negative physiological health consequences by decreasing cardiovascular and respiratory function. The good news is everyone has the means to measure their cardiorespiratory fitness and most individuals can improve it through regular physical activity.
Measuring VO2 max is used to assess and provide information regarding cardiorespiratory, or aerobic, fitness. VO2 max is the bodies maximal capacity to bring in oxygen to the muscles, and is measured in milliliters of oxygen used in one minute per kilogram of body weight (mL/kg/min). Determining oxygen consumption is one of the best gauges of someone’s level of aerobic fitness. Along with indicating cardiorespiratory fitness, VO2 max is measured to determine a baseline, individualized exercise prescription, and provide the best assessment of disease presence. There an numerous ways to measure an individuals vo2 max, however, some are more accurate than others, and each method comes with its own pros and cons.
Ways to measure vo2 max include direct and indirect methods, as well as submaximal or maximal protocols. Submaximal testing takes less time to perform, is less expensive, does not require physician supervision, and is safer for those with a known disease, however, it has a higher error rate in measuring vo2 max and maximal heart rate. Maximal testing is more accurate because it’s the closest we can get to a vo2 max, but its downsides include how costly and time consuming it is, the motivation of the individual doing the test, and a greater risk involved. The truest measure of energy expenditure/VO2 is called direct calorimetry which would involve a human chamber. A direct method of measuring maximal oxygen consumption(vo2 max) is performed in a laboratory, and it involves measuring the exhaled oxygen and carbon dioxide levels while an individual is continuously breathing through a mask and performing an ergometric test (often times running on a treadmill or cycling). Although direct calorimetry provides the single most accurate/reliable measure of cardiorespiratory fitness, it has some disadvantages that include having a very high cost. This means a direct measure using a maximal protocol would be the ideal way to cardiorespiratory fitness, but that would be in a perfect setting where money, resources, space, and the clients health weren’t an issue. Some other more cost effective, yet less accurate methods include indirect measures of vo2 max. Indirect measures include field tests, and they estimate a person’s aerobic fitness based off their heart rate or sometimes time of test/ distance covered.
Regardless of which method is chosen for measurement of vo2 max, the person undergoing testing should be evaluated to make sure the given test is appropriate and safe for them to do. When it comes to choosing a test, all of the following should be considered: the expertise of the person administering the test, the reason for having the test, and the clients health. It is important to look for cardiovascular risk factors, and get medical clearance if necessary, especially when performing a maximal test. Once the health screen is complete, the test administer should explain the RPE (rate of perceived exertion) scale, take all resting measurements, allow participant ask questions, and determine test termination criteria. Knowing vo2 max is beneficial because it can easily be transferred into energy cost and help individualized a clients exercise prescription and programming, like the one attached. Although aerobic training is sure to be the most effective at improving your cardiovascular fitness, there is also research that suggests anaerobic, or resistance, training can be beneficial for cardiorespiratory fitness.
Many of the positive changes will start to take place in about 8 – 12 weeks with training that is working all major muscle groups 2-3 days per week. It is advised to incorporate a warm up, cool down, and stretching when training. As one begins resistance training, they start to build muscle mass which will allow them to work harder, longer and burn more calories which increases the resting metabolic rate and improves health. This change can improve body composition by decreasing fat percentages which is great for cardiovascular health and fitness. Along with an increase in metabolic rate, resistance training can improve heart function. Anaerobic exercise increases the blood flow to the working muscles because the heart can pump more blood in less beats since the heart is stronger and less demand is placed on it. There is research to suggest that isometric resistance training can help keep a healthy blood pressure. Another way training improves cardiorespiratory health is by physiological changes to the muscle cells. Long term resistance training helps more oxygen reach the muscles, and it can increase the number of mitochondria in the muscle cells. Mitochondria produce ATP which provide energy to the muscle cells, so an increase in mitochondria means there’s more energy for the muscle to expand. Training should help will bone health and balance as well. These benefits that resistance training produce should be considered when planning an exercise regimen. Including both resistance and aerobic training is ideal for improving total cardiorespiratory fitness.
