Consider how you can feel breathless when going up a flight of stairs quickly—your body is showing the need for oxygen. “Aerobic” means “with oxygen,” and aerobic fitness, otherwise referred to as cardiorespiratory endurance, pertains to how well your body is able to take in oxygen and put that oxygen to use. Activities that involve large-muscle groups engaged in dynamic movement for prolonged periods of time are considered aerobic (2, 6). Your cardiovascular system (heart and blood vessels) and your respiratory system (lungs and air passages) work together during longer-duration activities to supply working muscles and organs with the oxygen they need. Examples of aerobic activities include walking, jogging, running, cycling, swimming, dancing, hiking, and team sports such as basketball and soccer.
Health and Fitness Benefits of Aerobic Activity
Regular and consistent aerobic activity improves your cardiorespiratory endurance. In other words, your heart, blood vessels, and lungs benefit from working harder than normal. Exercise improves your cardiorespiratory function by increasing the activity of these organ systems above what they experience at rest. Over time, your body adapts to these stresses and your fitness improves (2, 6).
Cardiorespiratory endurance is an important aspect of health for a number of reasons (2, 6, 8):
· Better cardiorespiratory endurance typically leads to higher levels of routine physical activity as you go about your day-to-day life. This in turn provides additional health benefits.
· Low levels of cardiorespiratory fitness are associated with higher risk of premature death from all causes, and specifically from cardiovascular disease. To look at this from a more positive perspective, increases in cardiorespiratory fitness are associated with a decreased risk of death from all causes.
· Aerobic fitness is an important foundation that allows you to engage in activities of daily living with greater ease.
· Increases in cardiorespiratory endurance allow you to more fully participate in recreational and sport activities.
· Aerobic activities that promote cardiorespiratory endurance also burn a relatively large number of calories and thus help to maintain appropriate body weight.
This is not an exhaustive list but does demonstrate the wide-ranging benefits of aerobic exercise for health as well as fitness.
Aerobic exercise improves cardiorespiratory endurance.
Aerobic Fitness Assessments
Assessing aerobic fitness can provide helpful insights on your current status as well as on the progress you are making in your exercise program over time. Before engaging in any active measurement, be sure to complete the preparticipation screening steps (including follow-up with your health care provider if indicated) outlined in chapter 2. This process is intended to help verify your readiness for exercise testing and future physical activity. If you are already currently active and have no cardiovascular, metabolic, or renal disease, then you can consider any of the assessments described in the following section. If you have not been regularly active, or if you have noted any medical condition warranting lower exercise intensity or have any activity restrictions recommended by your health care provider, then select less intense assessments and consider consulting with your health care provider to ensure you are ready for exercise testing. Additional considerations are provided for each assessment described in the following sections.
Assessing Heart Rate
Perhaps the simplest fitness assessment reflecting aerobic fitness is heart rate, which is reported in beats per minute. Heart rate naturally increases during exercise. The higher the intensity, the faster your heart must beat to bring oxygen and nutrients to your working muscles. As you gain fitness, however, your heart rate will be lower at rest as well as in response to a given level of exercise. As a result of aerobic training, the heart becomes a better pump. Your heart can now do the same job while beating more slowly because it is able to push out more blood with each heartbeat. This is evidence of your body adapting to the exercise and improvement in your cardiorespiratory fitness.
You can determine your heart rate by finding a location on your body where an artery (a blood vessel carrying blood from the heart to the rest of the body) is close to the surface of the skin so you can feel your pulse, which is the slight surge in blood flow that occurs when the heart contracts. Common locations are the radial artery in the wrist and the carotid artery in the neck (see figure 5.1). Use the tips of your middle and index fingers to feel your pulse. If you use the carotid, be sure to keep the pressure light. Too much pressure at this location can alter your heart rate artificially.
Figure 5.1 (a) Carotid and (b) radial artery pulse locations.
Resting heart rate can be determined first thing in the morning or when you have been seated, relaxed, and inactive for a period of time. To measure resting heart rate you will need a timing device that displays time in seconds. Locate one of the arteries just described, and simply count the number of beats (pulses) you feel for 1 minute.
Q&A
What is a typical resting heart rate for an adult?
For most adults, the number is between 60 and 100, but if your heart rate is lower than 60 or higher than 100 after multiple resting measurements, you should mention this to your health care provider.
Exercise heart rate is just as easy to measure as resting heart rate, but because heart rate steadily returns to a resting rate once you stop physical activity, finding your pulse and beginning your count immediately upon stopping is important. Take your pulse for 15 seconds and multiply the resulting number by 4. The answer is your exercise heart rate in beats per minute.
If manually taking your pulse is too difficult, consider making an investment in a heart rate monitor (an example is shown in figure 5.2). A heart rate monitor allows for a constant real-time readout of your heart rate by way of a transmitter (worn around the chest) that electronically communicates with a receiver that looks like a wristwatch. Heart rate is displayed on the receiver in beats per minute. The cost of heart rate monitors varies widely depending on their features (e.g., programmable heart rate zones, memory features to download to a computer after a workout, timekeeping functions). The simplest models that display only heart rate typically cost around $25. They are very durable and allow for easy checks of your heart rate during exercise.
Figure 5.2 Heart rate monitor.
Estimating Aerobic Fitness Level
Aerobic fitness is typically assessed by looking at maximal oxygen consumption, also called 
O2max. O2max is a marker of your body’s ability to take in and use oxygen. The higher this value is, the better your aerobic fitness is (2). Complex laboratory tests can most precisely determine your O2max, but you can get a reasonable estimate from simple tests such as the Rockport One-Mile Walking Test or the 1.5-mile run test, both of which are described in this section. Other assessments are available for older people (e.g., 6-minute walk test) as well as younger individuals. For youth, a shorter-distance run test is often used (see One-Mile Run Test for Youth later in this chapter) (3).
Select one of these tests based on your current health status, as well as physical activity and perceived fitness level. The walking test is more appropriate if you are planning to begin an exercise program after a period of inactivity or currently engage in moderate levels of exercise. If you are healthy and more active, the run test is another option. Each test and the associated calculations produce an estimation of your aerobic capacity. Use that result and the numbers provided in table 5.1 to determine your fitness level by age and sex (2).
Rockport One-Mile Walking Test
The Rockport One-Mile Walking Test is a way to estimate O2max (2). To complete this test, you should have the ability to walk 1 mile continuously. Choose a day without windy weather for testing. Ideally, you should perform the One-Mile Walking Test using an outdoor or indoor running track so that you can be certain that the distance you walk is no more or less than 1 mile. A standard quarter-mile track would be ideal (four laps on the inside lane), but many tracks are metric. If you are on a 400-meter track, then you will need to complete four laps on the inside lane plus an additional 9.3 meters (equal to approximately 31 ft). If a track is not available, any measured course will work as long as the surface is smooth and the course is flat. Grab a comfortable pair of shoes and a stopwatch. Walk the course as rapidly as you can without jogging or running, and record the time it takes for you to complete the mile. You also need to take your pulse as previously described immediately after you complete the mile walk.
Computing your results from the Rockport One-Mile Walking Test takes a bit of work, but the math is very simple when you plug results into one of the formulas shown here (numbers in bold are constant in the equations and thus are predetermined):
Males
139.150
Minus (0.1692 × ____ weight in kilograms)
Minus (0.3877 × ____ age in years)
Minus (3.2649 × ____ time in minutes)
Minus (0.1565 × ____ heart rate in beats per minute)
= ____ Aerobic capacity
Females
132.835
Minus (0.1692 × ____ weight in kilograms)
Minus (0.3877 × ____ age in years)
Minus (3.2649 × ____ time in minutes)
Minus (0.1565 × ____ heart rate in beats per minute)
= _____ Aerobic capacity
To obtain your weight in kilograms, multiply your weight in pounds by 0.454. For the time factor, you might wonder how to account for the number of seconds. For example, suppose you completed the one-mile walk in 14 minutes and 25 seconds. The 25 seconds needs to be expressed as a fraction (decimal number) of a minute. To do that, simply divide the number by 60 (because there are 60 seconds in a minute). In this case, 25 seconds would be about 0.42 of a minute, so you would use the number 14.42 in your calculation of aerobic capacity.
The answer you calculate is your aerobic capacity and refers to the amount of oxygen your body can use each minute—more specifically, the number of milliliters of oxygen your body uses per unit of body weight every minute (mL·kg−1·min−1). The more oxygen your body can use, the better your aerobic fitness level is. Once you have determined your aerobic capacity, find your fitness classification level in table 5.1.
1.5-Mile Run Test
Just as the Rockport One-Mile Walking Test is a way to estimate aerobic capacity, so too is the 1.5-mile (2.4 km) run (2). Because of the higher intensity and longer distance of this test, it is not appropriate for beginners, anyone with symptoms of or known heart disease, or anyone with risk factors or other health concerns as determined by a health screening or a health care provider.
To perform this test, choose a day without windy weather and use an outdoor or indoor running track. If you are on a quarter-mile track, this will involve six laps in the inside lane. If you are using a 400-meter track, it will involve six laps plus an additional 14 meters (46 ft) to complete the full distance of 1.5 miles. Wear a comfortable pair of running shoes and have a stopwatch handy. Because this test requires you to run as fast as you can for 1.5 miles, you should walk a lap or two to warm up. At the track, run as rapidly as you can for 1.5 miles, timing yourself to the nearest second. For this test, there is no need to record your heart rate. This test is challenging, so be sure to walk a lap or two to cool down after completion, and rehydrate as needed afterward.
The math used to interpret your results is much simpler than that for the Rockport One-Mile Walking Test. Use the following formula to estimate your aerobic capacity:
Aerobic capacity = (483 ÷ ____ time in minutes) + 3.5
As with the One-Mile Walking Test, this calculated value is an estimate of your aerobic capacity, or O2max. Because the number itself may not have much meaning, be sure to consult table 5.1 to check on your status compared to others of your age and sex (2). The higher the value, the better.
6-Minute Walk Test
Although some older adults may be comfortable completing the one-mile walk or 1.5-mile run test, another option is a 6-minute walk test (7). The 6-minute walk test could also be considered if you have been very inactive and are currently deconditioned. The test requires you to determine the distance you can walk in 6 minutes around a 50-yard (45.7 m) rectangular area (see figure 5.3 for the setup showing the number of yards walked). Focusing on a time rather than a particular distance covered allows individuals of all abilities to assess their fitness. Normal ranges for older adults are found in table 5.2. If your score is over the range listed, consider yourself above average; if your score falls short of the range, consider yourself below average (7).
Figure 5.3 Setup for 6-minute walk.
Adapted by permission from R.E. Rikli and C.J. Jones, 2013, p. 76.
One-Mile Run Test for Youth
FitnessGram is an assessment for children that emphasizes personal fitness for health rather than comparisons among children (3). With this philosophy in mind, healthy ranges are given rather than fitness rankings. Youth are considered in the “healthy fitness zone” or “needs improvement” zone. For boys and girls between the ages of 10 and 17, a one-mile run test is used (if a child cannot run this entire distance, encourage walking at a fast pace). For the one-mile run test, the calculation to estimate aerobic capacity (O2max) takes into account body mass index (BMI) as well as the time to complete the one-mile run (5).
Boys
108.94
Minus (8.41 × ____ mile time in minutes)
Plus (0.34 × ____ mile time in minutes × ____ mile time in minutes)
Plus (0.21 × ____ age in years)
Minus (0.84 × ____BMI)
= ______Estimated O2max
Girls
108.94
Minus (8.41 × ____ mile time in minutes)
Plus (0.34 × ____ mile time in minutes × ____ mile time in minutes)
Minus (0.84 × ____BMI)
= ______Estimated O2max
Note that this estimation can be used only for run times of 13 minutes or less. If the child requires more than 13 minutes to complete the one-mile run, then simply enter “13” into the formula for the mile time. To determine BMI, see figure 18.1. See table 5.3 for the healthy fitness zone for boys and girls between the ages of 10 and 17 (4).
Aerobic Workout Components
An aerobic workout should follow a consistent pattern to optimize safety as well as enjoyment (2). You should begin with a warm-up, which is followed by the main part of the workout, called the endurance conditioning phase. The workout is then wrapped up with a cool-down. See figure 5.4 for an overview of an aerobic exercise session.
Figure 5.4 Overview of aerobic exercise session.
Adapted from B. Bushman and J.C. Young, 2005, p. 35.
Warm-Up
A warm-up that consists of a minimum of 5 to 10 minutes of low- to moderate-level activity is essential (2). The intent of the warm-up is to increase the temperature of the muscles, thus preparing the body for the demands of the endurance conditioning phase, or main focus, of the workout. A warm-up prepares your heart, lungs, and muscles for the endurance conditioning phase of your aerobic training session (2) and may reduce the risk of injury (6). Think of the warm-up as an on-ramp to a freeway. The on-ramp gives you time to bring your vehicle up to the speed of traffic to avoid an accident. The faster the traffic is, the longer the on-ramp should be. In the same way, your warm-up should be longer if the intensity of the conditioning phase is high.
Warm-up activities may include some light calisthenics or lower-level activities similar to what you will be including in the conditioning phase. For example, if your program includes brisk walking for the conditioning phase, then the warm-up could include slower-paced walking. If the conditioning phase includes a more intense activity such as running, then jogging would be appropriate in the warm-up. The point is to gradually increase the intensity from resting levels to the intensity you plan for the conditioning phase.
Endurance Conditioning Phase
To continue with the freeway analogy, the endurance conditioning phase is the freeway itself—the main focus of your journey. The conditioning phase for aerobic activity is guided by the FITT-VP principle, which stands for frequency, intensity, time, type, volume, and progression (2). Frequency refers to the number of days per week you set aside time for exercise. Intensity reflects how hard you are working when exercising. Time simply refers to the duration you are active, on a daily or weekly basis. Type, or exercise mode, focuses on activities that involve large-muscle groups to improve cardiorespiratory fitness. Volume reflects the total amount of exercise and may be expressed in the number of calories burned. Progression refers to the manner in which the program is advanced over time as your fitness level improves.
Although FITT-VP nicely summarizes the conditioning phase, you will also want to add an “E”—the E stands for enjoyment. All the recommendations and information in the world mean little if you do not stick with your exercise program. Understanding the benefits of an exercise program (as outlined in chapter 1) may keep you active, but considering the time commitment you are making, you should also be sure you are having some fun. Suggestions for keeping exercise enjoyable are found later in this chapter. First, consider the nuts and bolts of an aerobic exercise program.
Frequency
The recommended frequency of aerobic exercise is three to five days per week. How many days you exercise depends on your goals and the intensity that is most appropriate for you. Although as few as a couple of days per week of activity can provide benefits, regular physical activity provides more benefits and has a lower risk of musculoskeletal injury than sporadic activity (2, 6). You will need as few as three days per week if you are engaging in vigorous activity, but at least five days per week is recommended if you plan on moderate-intensity activity. For example, if you enjoy running (a vigorous activity), three days per week will provide you with health and fitness benefits. However, if you plan on a walking program (a moderate-intensity activity), then at least five days per week would be better. If you enjoy mixing types and intensities of activity, then a weekly combination of three to five days of moderate and vigorous activity is recommended (2, 8). For example, you may walk a couple days per week and jog on another couple days. This would be considered two days per week of moderate activity (i.e., walking) and two days per week of vigorous activity (i.e., jogging), allowing you to meet the recommended amount of physical activity.
Intensity
As the intensity of activity increases, so do the potential health benefits. To promote health and fitness benefits, your exercise must place some stress on your cardiorespiratory system. In other words, you should notice an increase in your heart rate and breathing. When speaking of intensity, fitness professionals generally use the terms moderate and vigorous (2, 8). To help visualize this, consider moderate-intensity activity to be equivalent to brisk walking and vigorous-intensity activity to be equivalent to jogging or running (8).
A variety of simple methods are available to help you quantify the intensity of your exercise bout. One method is to monitor your relative level of effort. Although this is subjective (i.e., you determine how easy or hard you are exercising), a numerical scale can help guide you to appropriate levels of activity. The U.S. Department of Health and Human Services’ Physical Activity Guidelines for Americans suggests a scale of 0 to 10. Sitting at rest is 0, and your highest effort level possible is 10 (8). Moderate-intensity activity is a 5 or 6 on this effort scale. Vigorous-intensity activity is at a level of 7 or 8. This method allows you to individualize your exercise based on your current level of cardiorespiratory fitness (8). For an example of applying this scale, see figure 5.5.
Figure 5.5 Sample scale for where activities fall within the various intensity levels.
Another method, called the talk test, can also be used to establish exercise intensity (2). If you are working at an intensity that increases breathing rate but still allows you to speak without gasping for breath between words, you are likely exercising at a moderate intensity. The goal would be to exercise to the point at which speech would start to become more difficult. The Physical Activity Guidelines for Americans suggests that moderate-intensity activity allows you to talk but not to sing, whereas more vigorous activity results in an inability to say more than a few words without pausing for a breath (8).
Heart rate monitoring can also be helpful for determining your intensity level, although it is a bit more technical than the subjective measures of effort level and the talk test. Maximal heart rate can be estimated by subtracting your age in years from 220 (2). Thus for a 40-year-old, estimated maximal heart rate would be 180 beats per minute (i.e., 220 − 40 = 180). You will not be exercising at maximal heart rate, but rather at a percentage of that value; the percentage will depend on your target level of intensity (2). Multiply your estimated maximal heart rate by the activity factor from table 5.4 to determine your target heart rate.
__ estimated maximal heart rate × __ activity factor = target exercise heart rate in beats per minute
Note that your heart rate can also be influenced by environmental conditions (e.g., hot, humid environments) as well as medications (e.g., beta-blockers used for migraines and heart disease can lower heart rate). The calculated value should be used in conjunction with relative perception of effort or the talk test (2). You can adjust your workload up or down depending on your perception of effort on a given day.
Recognize, too, that you can vary your intensity during the conditioning phase. Athletes often use interval training, which includes some time at higher intensity followed by lower-intensity exercise. This provides a unique stress on the body that translates into improved aerobic fitness. This principle can be used for general exercise programs as well (2). For example, if you are just beginning to exercise, you could include a few minutes at a faster walking pace within your conditioning phase. Alternating between lower and higher intensity provides variety as well as a stimulus to improve your aerobic capacity, no matter your current level of fitness.
Q&A
How can interval training be designed to provide variety in an exercise program?
Interval training occurs when exercise intensity varies during an exercise session. This type of training provides many options, as you can change the number, duration, and intensity of various phases of the exercise session (2). For example, you could engage in moderate exercise at a level 5 (on the10-point exertion scale) for 2 minutes followed by 3 minutes of vigorous exercise at a level 7 (on the 10-point exertion scale) and repeat that sequence four times for a total of 20 minutes for the exercise session. To provide variety, you can change the time spent or the intensity of each of the different intervals. For example, 2 minutes at level 6 followed by 2 minutes at level 8 could be repeated five times for a total of 20 minutes for the exercise session. The options are almost limitless and can be individualized based on your current health and fitness status (2).
Time
The duration of each of your exercise sessions is determined by the amount of time you are able to commit as well as your current fitness status. If you are a beginner, don’t worry about some arbitrary time goal; rather, find an activity that you can do continuously for 10 minutes. Increase the duration of the exercise session as it becomes easier to complete. Add a couple of minutes per session until you reach about 30 minutes of aerobic exercise per day. Depending on your initial fitness level, this may take weeks or even a month or more. The key is to keep going and make progress.
If you have already been doing some exercise (or have now built up to 30 minutes of continuous activity) and feel comfortable with moderate-intensity activity for this length of time, decide whether you want to maintain your current intensity and go for a bit longer, or if you want to begin to increase the intensity. Time and intensity are like a teeter-totter. When you increase intensity, you generally decrease the length of the session. If you decrease intensity, you will need to increase the time you spend exercising to achieve full health benefits. A general rule of thumb from the Physical Activity Guidelines for Americans is that 1 minute of vigorous-intensity activity can be counted as the same as 2 minutes of moderate-intensity activity (8). For example, a 15-minute run would provide the same health benefit as a 30-minute walk.
Labels are difficult to apply universally, but table 5.5 provides some terminology related to activity status that was introduced in chapter 2. For the purposes of this book, beginners are those who currently have limited activity. As you can see in the table, beginners are focusing on very light to light activity and build up to 100 to 150 minutes per week of light to moderate activity. The intermediate level of activity reflects people who are somewhat active and are moderately conditioned. The focus at this stage is increasing moderate-intensity aerobic activity to 150 to 250 minutes per week. Typically, people at this level are of fair to average fitness levels. Established exercisers are those who have been engaged in regular exercise for at least six months. Fitness levels vary according to genetic potential as well as personal fitness goals. Typically, established exercisers have average to excellent aerobic fitness.
The Physical Activity Guidelines for Americans recommends working toward a minimum of 150 minutes per week of moderate-intensity activity, or 75 minutes per week of vigorous-intensity activity (8). If you are already physically active at this level, then consider increasing your activity to gain additional health and fitness benefits. For you, a new target of 300 minutes per week of moderate-intensity activity, or 150 minutes per week of vigorous-intensity activity, would be a potential goal (8).
Walking and jogging are common aerobic activities.
Type or Mode
Aerobic activities are grouped into four categories along with recommendations on who would most appropriately engage in the given activity (see table 5.6) (2). Exercises in group A are recommended for everyone because they are relatively simple activities that can be started at a low level of effort. Group B activities are more vigorous and thus are most appropriate if you already have a good fitness base (i.e., you have been exercising regularly and have determined your fitness level to be at least in the fair to average range). Group C activities are those that have a definite skill component and thus may require some learning before being used as a fitness tool. Group D activities are recreational and, because intensity varies depending on the situation, are best reserved for people who are regularly active and have a good fitness base. Do not consider these groupings progressive (e.g., that group C activities are better than group B activities), but rather as a way to classify various aerobic exercises.
Volume
The concept of volume reflects a summary or overall amount of activity. One way to provide a summary of your aerobic exercise is to determine the calories you use when engaging in your aerobic activities each week. When considering the activity recommendations in the Physical Activity Guidelines for Americans, a reasonable target is at least 1,000 calories per week (2). Calculating calories burned can be helpful when you are interested in losing weight, but it is also a great way to pull together the four parts of your aerobic exercise prescription—frequency, intensity, time, and type of activity—into one number. Whether you do the same activity each day or change it up, you still can take a look at your weekly total to ensure that you are on track with just a few calculations.
To keep things simple, researchers have created a unit of measure called a metabolic equivalent, or MET. A MET is equal to the oxygen cost at rest (i.e., 1 MET = resting level = 3.5 milliliters of oxygen per kilogram body weight per minute). Multiples of a MET are then applied to various activities. For example, walking at 3.5 miles per hour (5.6 km/h) is equal to 4 METs. In other words, you are working four times harder when walking at 3.5 miles per hour than you are when seated in a resting position. Metabolic equivalent values have been determined for a wide variety of activities (see table 5.7 for some examples of basic activities) (1).
Once you know the MET value for a given exercise, you can estimate how many calories you burned per minute by inserting that value into the following formula (numbers in bold are constants—in other words, they do not change):
____ MET value of activity × 3.5 × ___ body weight in kg ÷ 200
= ____ calories burned per minute
Insert the MET value for the activity and then your body weight (to convert from pounds to kilograms, multiply your weight in pounds by 0.454 to determine your weight in kilograms). For an example on how this can be used, see Checking Volume of Aerobic Exercise.
Checking Volume of Aerobic Exercise
To compare two programs—one focused on walking and the other on jogging—take a look at the MET values to help you examine how intensity influences the number of calories burned.
· Walking program: walking 3.5 miles per hour (5.6 km/h) for 50 minutes
· Jogging program: running at 5 miles per hour (8 km/h) for 25 minutes
For this example, the calculations are done for a 150-pound (68.1 kg) person. The MET values for each activity are found in table 5.7.
Walking at 3.5 miles per hour (5.6 km/h) is equal to 4.3 METs, so using the formula provided previously, a 50-minute workout burns about 255 calories (determined by multiplying 5.1 calories per minute by the workout duration of 50 minutes), as follows:
(4.3 METs × 3.5 × 68.1 kg) ÷ 200 = 5.1 calories per minute
Running at 5 miles per hour (8 km/h) is equal to 8.3 METs, so using the formula provided previously, a 25-minute workout would burn 248 calories (determined by multiplying 9.9 calories per minute by the workout duration of 25 minutes), as follows:
(8.3 METs × 3.5 × 68.1 kg) ÷ 200 = 9.9 calories per minute
The two workouts burn approximately the same number of calories. Thus even though the activities are very different, the overall volume (which accounts for the type, duration, and intensity) is similar.
Progression
Progression is how an exercise program is advanced over time. Many factors must be considered, including current health and fitness status, training responses, and goals (2). The key is gradual progression rather than making abrupt or significant changes in one of the FITT components. If you are just starting, to optimize safety and avoid injury, the recommendation is “start low and go slow” (2). Table 5.5reflects this concept of slowly increasing the volume of exercise. Rather than increasing frequency, intensity, and duration all at once, you want to gradually introduce changes. For example, initially, you may simply increase the time spent in activity. As you adjust to this level of activity, you may then want to cut back the time a bit and increase the intensity slightly. Reflect on the overall volume of exercise to help make sure your progression is gradual. As you make adjustments to your program, give yourself time at a particular volume of activity to ensure you are able to maintain this new level before trying to move forward.
Cool-Down
The cool-down should consist of a minimum of 5 to 10 minutes of low- to moderate-level activity (2). The cool-down provides an opportunity for body systems to gradually return to preexercise levels. A cool-down is recommended to allow the heart to slow down in a controlled manner, thus avoiding negative changes in heart rhythm. In addition, if you stop your activity too abruptly, blood that was circulating to the working muscles can pool in your legs, resulting in a drop in blood pressure. A cool-down also helps to gradually decrease body temperature, which naturally increased during the endurance phase. Activities included in a cool-down are similar to those in the warm-up, but the intensity needs to gradually diminish toward resting levels (2).
A proper cool-down is driven by both practical issues (e.g., avoiding fainting from a drop in blood pressure) and safety issues (e.g., avoiding negative changes in heart rhythm). The cool-down is like a freeway off-ramp. When shifting from freeway speeds to those appropriate on city streets, time is needed for an adjustment. In a similar way, the cool-down allows the body to adjust back toward normal resting levels. The higher the intensity of your conditioning phase, the longer your cool-down should be.
Your Aerobic Program
If you are just getting started with your exercise program, be sure to complete the preparticipation screening process found in chapter 2 (2). This screening can help you determine whether you should visit your health care provider before starting an exercise program. Of course, regardless of the outcome, consulting with your personal health care provider is always appropriate. In addition, you need to consider your current fitness level and begin at a point suitable to your current status. Over time, with regular activity, you will progress and improve.
Your personal exercise prescription takes into account the frequency, intensity, time, and type of activity. Take walking, for example, which is the most commonly reported exercise and is a great activity for the start of an exercise program (walking is a group A activity as shown in table 5.6). Figure 5.6 shows an example of a progressive walking and jogging program. You can determine where to enter into the exercise progression based on your current level of fitness.
Once you feel comfortable with 30 minutes of continuous moderate-intensity activity, you may be interested in other activity options. Swimming, a group C activity, is another excellent aerobic activity if you have basic swimming skills or are willing to gain those skills. Follow the time and intensity progression described in figure 5.6, substituting swimming (using different strokes for variety) for walking and jogging.
Figure 5.7 provides a sample program for someone with a membership at a health club. Activities at the club, when done at a low intensity, would fall into group A, but as the person’s fitness level improves, the intensity increase will likely result in a shift to group B exercise.
The examples in figures 5.6 and 5.7 show a progression from beginner to established exerciser. Depending on your current status, you may be at the start of the table as a beginner or already in the established, or maintenance, phase. If you are just beginning to exercise, progress slowly and base your advancement on how your body is responding to the exercise. If you are in the established, or maintenance, phase, keep tracking your activity. Also, stay focused on the FITT-VP factors as discussed previously, and if you are becoming bored with your current activity program, consider other modes of exercise or joining an exercise group.
As you move along in your exercise journey, increase the duration (time) first; once you are comfortable with the activity at the longer session length, then consider increasing the intensity. To avoid injury, do not increase the session duration and intensity at the same time. Although placing a stress on the body is necessary for improvement, excessive overload can result in injury as well as frustration. To keep steady forward progress, refer to table 5.5 for general guidance.
In addition, as you examine the sample programs, once again consider the FITT-VP factors as discussed earlier and how each relates to your fitness goals. Don’t forget about enjoyment. As you create your plan of action, consider the types of activities that you enjoy and that also are accessible to you. Joining a health club can be a great way to increase your access to a variety of activities (equipment as well as group classes). If you don’t want to join a health club, you can easily find aerobic activities at no cost. Walking and running trails are becoming more common in cities; many malls open their doors early to allow walkers to use the corridors before the stores open; and your local library has many aerobic exercise videos that you can use in the privacy of your own home. To get started, you need to pick a day and take the first step—literally as well as figuratively.
Cardiorespiratory (or aerobic) fitness is important for promoting health and, in particular, is associated with a reduced risk of cardiovascular disease. An aerobic exercise session includes a warm-up, a conditioning phase, and a cool-down. The warm-up and cool-down are links between the resting state and the exercise portion of your workout. The main focus, the endurance conditioning phase, is guided by the FITT-VP principle: frequency, intensity, time, type, volume, and progression. General recommendations are as follows: three to five days per week (frequency), moderate to vigorous level of exertion (intensity), 20 to 30 minutes or more per session (time), large-muscle group activity (type of activity), total of 1,000 calories burned per week (volume), and gradual increases over time (progression). In addition, tracking aerobic fitness assessments periodically is a helpful way to determine current status and the effectiveness of your aerobic exercise program.