Exercise Physiology: For Health, Fitness, and Performance_2 pdf

388

Cardiorespiratory Training Principles

and Adaptations

After studying the chapter, you should be able to:

■ Describe the exercise/physical activity recommendations of the American College of Sports Medi￾cine, the Surgeon General’s Report, the ACSM/AHA Physical Activity and Public Health Guidelines,

the National Association for Sport and Physical Education, and the CDC Expert Panel. Discuss why

these reports contain different recommendations.

■ Discuss the application of each of the training principles in a cardiorespiratory training

program.

■ Explain how the FIT principle is related to the overload principle.

■ Differentiate among the methods used to classify exercise intensity.

■ Calculate training intensity ranges by using different methods including the percentage of maxi￾mal heart rate, the percentage of heart rate reserve, and the percentage of oxygen consumption

reserve.

■ Discuss the merits of specifi city of modality and cross-training in bringing about cardiovascular

adaptations.

■ Identify central and peripheral cardiovascular adaptations that occur at rest, during submaximal

exercise, and at maximal exercise following an aerobic endurance or dynamic resistance training

program.

13

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CHAPTER 13 • Cardiorespiratory Training Principles and Adaptations 389

INTRODUCTION

In the last decade, physical fi tness–centered exercise pre￾scriptions, which emphasize continuous bouts of rela￾tively vigorous exercise, have evolved (for the nonathlete)

into public health recommendations for daily moderate￾intensity physical activity. Early scientifi c investigations

that led to the development of training principles for

the cardiovascular system almost always focused on the

improvement of physical fi tness, operationally defi ned

as an improvement of maximal oxygen consumption

(V

.

O2

max). Such studies formed the basis for the guide￾lines developed by the American College of Sports Medi￾cine (1978) as “the recommended quantity and quality of

exercise for developing and maintaining fi tness in healthy

adults.” These guidelines were revised in 1998 to “the

recommended quantity and quality of exercise for devel￾oping and maintaining cardiorespiratory and muscular

fi tness, and fl exibility in healthy adults.” After 1978, these

guidelines were increasingly applied not only to healthy

adults intent on becoming more fi t but also to individuals

seeking only health benefi ts from exercise training.

Although evidence shows that health benefi ts accrue

when fi tness is improved, health and fi tness are different

goals, and exercise training and physical activity are differ￾ent processes (Plowman, 2005). The quantity and quality of

exercise required to develop or maintain cardiorespiratory

fi tness may not be (and probably are not) the same as the

amount of physical activity required to improve and main￾tain cardiorespiratory health (American College of Sports

Medicine, 1998; Haskell, 1994, 2005; Haskell et al., 2007;

Nelson et al., 2007). Furthermore, most exercise science

or physical education majors and competitive athletes who

want or need high levels of fi tness can handle physically

rigorous and time-consuming training programs. Such

programs, however, carry a risk of injury and are often

intimidating to those who are sedentary, elderly, or obese.

Studies also suggest that different physical activity

recommendations are warranted for children and adoles￾cents. Thus, an optimal cardiovascular training program—

maximizing the benefi t while minimizing the time, effort,

and risk—varies with both the population and the goal.

Table 13.1 summarizes recommendations for cardiorespi￾ratory health and fi tness from leading authorities.

APPLICATION OF THE TRAINING

PRINCIPLES

This chapter focuses on cardiovascular fi tness and car￾diorespiratory function that can impact health. Thus, the

exercise prescription recommendations of the ACSM, the

physical activity guidelines from the Surgeon General’s

Report (SGR, US DHS, 1996), and the Physical Activity

and Public Health Guidelines sponsored jointly by the

ACSM and the American Heart Association are discussed,

along with the guidelines for children/adolescents. The

emphasis will be on the changes that accompany a change

in V.

O2

max. Additional information about physical fi tness

and physical activity in relation to cardiovascular disease

is presented in Chapter 15.

Obviously, there are other goals for exercise pre￾scription and physical activity guidelines in addition to

cardiovascular ones. There is also some overlap in the

cardiovascular benefi ts of physical activity/exercise with

other health and fi tness areas, especially those pertain￾ing to body weight/composition and metabolic function.

Body weight aspects are discussed in the metabolic unit,

and the recommendations for and benefi ts of resistance

training and fl exibility are discussed in the neuromus￾cular unit.

The fi rst section of this chapter, focusing on how the

training principles are applied for cardiorespiratory fi t￾ness, relies heavily on the cardiorespiratory portion of

the 1998 ACSM guidelines for healthy adults. Cardio￾vascular fi tness is defi ned as the ability to deliver and

use oxygen during intense and prolonged exercise or

work. Cardiovascular fi tness is evaluated by measures of

maximal oxygen consumption (V.

O2

max). Sustained exer￾cise training programs using these principles to improve

V

.

O2

max are rarely included in the daily activities of chil￾dren and adolescents. However, in the absence of more

specifi c exercise prescription guidelines for younger

individuals, these guidelines are often applied to adoles￾cent athletes and youngsters in scientifi c training studies

(Rowland, 2005).

Specifi city

Any activity that involves large muscle groups and is sus￾tained for prolonged periods of time has the potential

to increase cardiorespiratory fi tness. This includes such

exercise modes as aerobics, bicycling, cross- country

skiing, various forms of dancing, jogging, rollerblad￾ing, rowing, speed skating, stair climbing or stepping,

swimming, and walking. Sports involving high-energy,

nonstop action, such as fi eld hockey, lacrosse, and

soccer, can also positively benefi t the cardiovascular

system (American College of Sports Medicine, 1998;

Pollock, 1973).

For fi tness participants, the choice of exercise modali￾ties should be based on interest, availability, and risk of

injury. An individual who enjoys the activity is more likely

to adhere to the program. Although jogging or running

may be the most time-effi cient way to achieve cardiorespi￾ratory fi tness, these activities are not enjoyable for many

individuals. They also have a relatively high incidence

of overuse injuries. Therefore, other options should be

available in fi tness programs.

Cardiorespiratory Fitness The ability to deliver and

use oxygen under the demands of intensive, pro￾longed exercise or work.

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390 Cardiovascular-Respiratory System Unit

TABLE 13.1 Physical Activity and Exercise Prescription for Health

and Physical Fitness

Modality

Source Frequency Intensity Duration Cardiorespiratory Neuromuscular

Surgeon

General’s

Report (1996)

Most, if not

all days of the

week

Moderate† Accumulate

30 min·d−1

Any physical activity burning ~150

kcal·d−1 or 2 kcal·kg·d−1

American

College

of Sports

Medicine

(1998)

3–5 d·wk−1 55*/65–90%

HRmax

40*/50–85%

HRR

Continuous

20–60 min or

intermittent

(³10-min bouts)

Rhythmical,

aerobic, large

muscles

Dynamic

resistance: 1 set

of 8–12

(or 10–15*)

reps; 8–10 lifts;

2–3 d·wk−1

40*/50–85%

V

.

O2

R

Flexibility: Major

muscle groups

range of motion;

2–3 d·wk−1

ACSM/AHA

(2007):

Healthy adults

18–65 y

5 d·wk−1

3 d·wk−1

Moderate

OR

Vigorous

30 min

20 min

8–10 strength training exercises

12 repetitions, 2d·wk−1

ACSM/AHA

(2007): Older

adults

As above 8–10 strength training exercises

10–15 repetitions, 2 d·wk−1; fl exibility

exercises 2 d·wk−1 and balance exercises

as needed

NASPE (2004):

Children

5–12 yr

All, or most

days

Moderate to

vigorous

60+ min·d−1

Intermittent,

but several

bouts >15 min

Age-appropriate aerobic sports

CDC Expert

Panel:

Children/

adolescents

6–18 yr

Daily Moderate to

vigorous

60+ min·d−1 Age appropriate (Strong et al., 2005),

enjoyable, varied

*Intended for least-fi t individuals. †

Examples include touch football, gardening, wheeling oneself in wheelchair, walking at a pace of 20 min·mi−1, shooting baskets, bicycling

at 6 mi·hr−1, social dancing, pushing a stroller 1.5 mi·30 min−1, raking leaves, water aerobics, swimming laps.

Sources: Haskell, W. L., I. Lee, R. R. Pate, et al.: Physical activity and public health: Updated recommendation for adults from the

American College of Sports Medicine and the American Heart Association. Medicine and Science in Sports and Exercise. 39(8):1423–1434

(2007); Nelson, M. E., W. J. Rejeski, S. N. Blair, et al.: Physical activity and public health in older adults: Recommendation from the

American College of Sports Medicine and the American Heart Association. Medicine and Science in Sports and Exercise. 39(8):1435–1445

(2007).

Although many different modalities can improve

cardiovascular function, the greatest improvements in

performance occur in the modality used for training,

that is, there is modality specifi city. For example, indi￾viduals who train by swimming improve more in swim￾ming than in running (Magel et al., 1975), and individuals

who train by bicycling improve more in cycling than in

running (Pechar et al., 1974; Roberts and Alspaugh,

1972). Modality specifi city has two important practical

applications. First, to determine whether improvement is

occurring, the individual should be tested in the modal￾ity used for training. Second, the more the individual is

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CHAPTER 13 • Cardiorespiratory Training Principles and Adaptations 391

muscles but not to habitually inactive ones. Other factors

within exercising muscles such as mitochondrial density

and enzyme activity also affect the body’s ability to reach

a high V.

O2

max. Specifi city of modality operates because

peripheral adaptations occur in the muscles that are

used in the training. Thus, specifi c activities—or closely

related activities that mimic the muscle action of the pri￾mary sport—are needed to maximize peripheral adapta￾tions. Examples of mimicking muscle action include side

sliding or cycling for speed skating and water running in

a fl otation vest for jogging or running.

One study divided endurance-trained runners into

three groups. One third continued to train by running,

one third trained on a cycle ergometer, and one third

trained by deep water running. The intensity, frequency,

and duration of workouts in each modality were equal.

After 6 weeks, performance in a 2-mi run had improved

slightly (~1%) in all three groups (Eyestone et al., 1993).

Thus, running performance was maintained by each

of the modalities. On the other hand, arm ergometer

training has not been shown to maintain training ben￾efi ts derived from leg ergometer activity (Pate et al.,

1978). Apparently, the closer the activities are in terms

of muscle action, the greater the potential benefi t of

cross-training.

Table 13.2 lists several situations, in addition to the

maintenance of fi tness when injured, in which cross￾training may be benefi cial (Kibler and Chandler, 1994;

O’Toole, 1992). Note that multisport athletes may or

may not be limited to the sports in which they are com￾peting. For example, although a duathlete needs to train

for both running and cycling, this training will have the

benefi ts of both specifi city and cross-training. In addi￾tion, this athlete may also cross-train by doing other

activities such as rollerblading or speed skating. Note

also that cross-training can be recommended at any

time for a fi tness participant to help avoid boredom.

For a healthy competitive athlete, the value of cross￾training is modest during the season. Cross-training

is most valuable for single-sport competitive athletes

during the transition (active rest) phase but may also

be benefi cial during the general preparation phase of

periodization.

Overload

Overload of the cardiovascular system is achieved by

manipulating the intensity, duration, and frequency of

the training bouts. These variables are easily remem￾bered by the acronym FIT (F = frequency, I = inten￾sity, and T = time or duration). Figure 13.1 presents the

results of a study in which the components of overload

were investigated relative to their effect on changes in

V

.

O2

max. As the most critical component, intensity will

be discussed fi rst.

concerned with sports competition rather than fi tness or

rehabilitation, the more important the mode of exercise

becomes. A competitive rower, for example, whether

competing on open water or an indoor ergometer, should

train mostly in that modality. Running, however, seems

to be less specifi c than most other modalities; running

forms the basis of many sports other than track or road

races (Pechar et al., 1974; Roberts and Alspaugh, 1972;

Wilmore et al., 1980).

Although modality specifi city is important for com￾petitive athletes, cross-training also has value. Originally,

the term “cross-training” referred to the development or

maintenance of muscle function in one limb by exercising

the contralateral limb or upper limbs as opposed to lower

limbs (Housh and Housh, 1993; Kilmer et al., 1994; Pate

et al., 1978). Such training remains important, especially

in situations where one limb has been injured or placed in

a cast. As used here, however, the term “cross-training”

refers to the development or maintenance of cardiovas￾cular fi tness by training in two or more modalities either

alternatively or concurrently. Two sets of athletes, in

particular, are interested in cross-training. First, injured

athletes, especially those with injuries associated with

high-mileage running, who wish to prevent detraining.

Second, an increasing number of athletes participate in

multisport competitions such as biathlons and triathlons

and need to be conditioned in each.

Theoretically, both specifi city and cross-training have

value for a training program. Any form of aerobic endur￾ance exercise affects both central and peripheral cardiovas￾cular functioning. Central cardiovascular adaptations

occur in the heart and contribute to an increased ability

to deliver oxygen. Central cardiovascular adaptations are

the same in all modalities when the heart is stressed to the

same extent. Thus, many modalities can have the same

overall training benefi t by leading to central cardiovascu￾lar adaptations.

Peripheral cardiovascular adaptations occur in the

vasculature or the muscles and contribute to an increased

ability to extract oxygen. Peripheral cardiovascular

adaptations are specifi c to the modality and the specifi c

muscles used in that exercise. For example, additional

capillaries will form to carry oxygen to habitually active

Cross-training The development or maintenance of

cardiovascular fi tness by alternating between or con￾currently training in two or more modalities.

Central Cardiovascular Adaptations Adaptations

that occur in the heart that increase the ability to

deliver oxygen.

Peripheral Cardiovascular Adaptations Adaptations

that occur in the vasculature or muscles that increase

the ability to extract oxygen.

Plowman_Chap13.indd 391 lowman_Chap13.indd 391 11/6/2009 9:04:15 PM 1/6/2009 9:04:15 PM

392 Cardiovascular-Respiratory System Unit

of 90–100% of V.

O2

max. In order to achieve such high

intensity, training individuals may alternate work and

rest intervals (interval training). At exercise levels greater

than 100% (supramaximal exercise), in which the total

amount of training that can be performed decreases,

improvement in V.

O2

max is somewhat less than is seen at

90–100% V.

O2

max.

Intensity

Figure 13.1A shows the relationship between change in

V

.

O2

max and exercise intensity. In general, as exercise

intensity increases, so do improvements in V.

O2

max. The

greatest amount of improvement in V.

O2

max is seen fol￾lowing training programs that utilize exercise intensities

TABLE 13.2 Situations in Which Cross-Training Is Benefi cial

Reason Fitness Participant Competitive Athlete

Multisport participation General preparation phase, specifi c preparation

phase, competitive phase

Injury or rehabilitation;

fi tness maintenance

As needed As needed

Inclement weather As needed As needed

Baseline or general

conditioning

Always General preparation phase

Recovery After intense workout After intense workout or competition

Prevention of boredom and

burnout

Always Transition phase

Source: Kibler, W. B., & T. J. Chandler: Sport-specifi c conditioning. American Journal of Sports Medicine. 22(3):424–432 (1994).

0

Frequency (sessions·wk–1)

Duration (min·session–1)

15–25 35–45

23456

25–35

Initial fitness level

VO2max (mL·kg–1·min–1)

30–40 40–50 50–60

Change in VO2 max (mL·kg–1·min–1) 8

6

4

2

0

8

6

4

2

C

B

D

Change in VO2 max (mL·kg–1·min–1)

0

8

6

4

2

Change in VO max 2 (mL·kg–1·min–1)

Intensity, % VO2max

50–70 90–100

8

6

4

2

0

A

Change in VO max 2 (mL·kg–1·min–1)

FIGURE 13.1. Changes in

V

.

O2

max Based on Frequency,

Intensity, and Duration of Training

and on Initial Fitness Level.

Source: Wenger, H., A., & G. J. Bell. The

interactions of intensity, frequency and

duration of exercise training in altering

cardiorespiratory fi tness. Sports Medicine.

3:346–356 (1986). Reprinted by permis￾sion of Adis International, Inc.

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CHAPTER 13 • Cardiorespiratory Training Principles and Adaptations 393

Example

Calculate the predicted or estimated HRmax for a

28-year-old female with a normal body composition.

HRmax = 220 − age = 220 − (28 yr) = 192 b·min−1

If the female is obese, her estimated HRmax is

HRmax = 200 − (0.5 × age) = 200 − (0.5 × 28 yr)

= 186 b·min−1

Once the HRmax is known or estimated, the %HRmax

is calculated as follows:

Target exercise heart rate (TExHR) = maximal heart

rate (b·min−1) × percentage of maximal heart rate

(expressed as a decimal)

or

TExHR = HRmax × %HRmax

13.2

1. Determine the desired intensity of the workout.

2. Use Table 13.3 to fi nd the %HRmax associated with

the desired exercise intensity.

3. Multiply the percentages (as decimals) times the

HRmax.

Example

Determine the appropriate HR training range for

a moderate workout for a nonobese 28-year-old

individual using the HRmax.

1. Determine the HRmax:

220 − 28 = 192 b·min−1

2. Determine the desired intensity of the workout.

Table 13.3 shows 55–69% of HRmax corresponds

to a moderate workout.

3. Multiply the percentages (as decimals) times the

HRmax for the upper and lower exercise limits.

Thus

HRmax 192 192

desired intensity (decimal) × 0.55 × 0.69

Target HR Range (rounded) 106 133

Thus, an HR of 106 b·min−1 represents 55% of HRmax

and an HR of 133 b·min−1 represents 69% of HRmax.

To exercise between 55% and 69% of HRmax, a moder￾ate workload, this individual should keep her heart rate

between 106 and 133 b·min−1.

It is always best to provide the potential exerciser

with a target heart rate range rather than a threshold

heart rate. In fact, the term “threshold” may be a mis￾nomer since no particular percentage has been shown

Intensity, both alone and in conjunction with duration,

is very important for improving V.

O2

max. Intensity may

be described in relation to heart rate, oxygen consump￾tion, or rating of perceived exertion (RPE). Laboratory

studies typically use V.

O2

for determining intensity, but

heart rate and RPE are more practical for individuals out￾side the laboratory. Table 13.3 includes techniques used

to classify intensity and suggests percentages for very

light to very heavy activity (American College of Sports

Medicine, 1998). Note that these percentages and classi￾fi cations are intended to be used when the exercise dura￾tion is 20–60 minutes and the frequency is 3–5 d·wk−1.

Heart Rate Methods

Exercise intensity can be expressed as a percentage

of either maximal heart rate (%HRmax) or heart rate

reserve (%HRR). Both techniques, explained below,

require HRmax to be known or estimated. The methods

are most accurate if the HRmax is actually measured

during an incremental exercise test to maximum. If

such a test cannot be performed, HRmax can be esti￾mated. ACSM recommends the following traditional,

empirically based, easy formula using age despite the

equation’s large (±12–15 b·min−1) standard deviation

(Wallace, 2006). This large standard deviation, based

on population averages, means that the calculated value

may either overestimate or underestimate the true

HRmax by as much as 12–15 b·min−1 (Miller et al., 1993;

Wallace, 2006).

maximal heart rate (b·min-1 13.1a ) = 220 − age (yr)

For obese individuals, the following equation is more

accurate (Miller et al., 1993):

maximal heart rate (b·min-1) = 200 − [0.5 ×

age (yr)]

13.1b

For older adults, the following equation is more accurate

(Tanaka et al., 2001):

maximal heart rate (b·min-1) = 208 − [0.7 ×

age (yr)]

13.1c

As indicated in Chapter 12, HRmax is independent of

age between the growing years of 6 and 16. This means

that the “220 − age (yr)” equation cannot be used for

youngsters at this age (Rowland, 2005). During this

age span for both boys and girls, the average HRmax

resulting from treadmill running is 200–205 b·min−1.

Values obtained during walking and cycling are typi￾cally 5–10 b·min−1 lower at maximum. As with adults,

measured values are always preferable but may not be

practical. Therefore, the value estimated for HRmax

for children and young adolescents should depend on

modality rather than age.

Plowman_Chap13.indd 393 lowman_Chap13.indd 393 11/6/2009 9:04:15 PM 1/6/2009 9:04:15 PM

394 Cardiovascular-Respiratory System Unit

Target exercise heart rate (b·min−1) = [heart rate

reserve (b·min−1) × percentage of heart rate re￾serve (expressed as a decimal)] + resting heart

rate (b·min−1)

or

TExHR = (HRR × %HRR) + RHR

13.4

Determine the appropriate HR range for a moderate

workout for a normal-weight, 28-year-old individual

using the HRR method, assuming a RHR of

80 b·min−1.

1. Determine the HRR:

192 b·min−1 − 80 b·min−1 = 112 b·min−1

2. Determine the desired intensity of the workout.

Again, using Table 13.3, 40–59% of HRR corre￾sponds to a moderate workout. This reinforces the

point that the %HRmax does not equal %HRR.

3. Multiply the percentages (as decimals) for the

upper and lower exercise limits by the HRR.

Thus

HRR 112 112

desired intensity (decimal) × 0.4 × 0.59

45 66

4. Add RHR as follows:

45 66

resting HR ±80 ±80

target HR training range (b·min−1) 125 146

continued

Example

to be a minimally necessary threshold for all individuals

in all situations (Haskell, 1994). Additionally, a range

allows for the heart rate drift that occurs in moderate

to heavy exercise after about 30 minutes and for varia￾tions in weather, terrain, fl uid replacement, and other

infl uences. The upper limit serves as a boundary against

overexertion.

Alternatively, a target heart rate range can be calcu￾lated as a %HRR, a technique also called the Karvonen

method. It involves additional information and calcula￾tions but has the advantage of considering resting heart

rate. The steps are as follows:

1. Determine the HRR by subtracting the resting heart

rate from the HRmax:

Heart rate reserve (b·min−1) = maximal heart rate

(b·min−1) − resting heart rate (b·min−1)

or

HRR = HRmax − RHR

13.3

The resting heart rate is best determined when the

individual is truly resting, such as immediately on

awakening in the morning. However, for purposes of

exercise prescription, this can be a seated or standing

resting heart rate, depending on the exercise posture.

Heart rates taken before an exercise test are anticipa￾tory, not resting, and are higher than actual resting

heart rate.

2. Choose the desired intensity of the workout.

3. Use Table 13.3 to fi nd the %HRR associated with the

desired exercise intensity.

4. Multiply the percentages (as decimals) for the upper

and lower exercise limits by the HRR and add RHR

using Equation 13.4.

TABLE 13.3 Classifi cation of Intensity of Exercise Based on 20–60 minutes

of Endurance Training

Relative Intensity

Classifi cation of intensity %HRmax %HRR/%V.

O2

R Borg RPE

Very light <35 <20 <10

Light 35–54 20–39 10–11

Moderate 55–69 40–59 12–13

Hard 70–89 60–84 14–16

Very hard ³90 ³85 17–19

Maximal 100 100 20

Source: American College of Sports Medicine: Position stand on the recommended quantity and quality of exercise for developing and maintaining

cardiorespiratory and muscular fi tness and fl exibility in healthy adults. Medicine and Science in Sports and Exercise. 30(6):975–985 (1998).

Plowman_Chap13.indd 394 lowman_Chap13.indd 394 11/6/2009 9:04:17 PM 1/6/2009 9:04:17 PM

CHAPTER 13 • Cardiorespiratory Training Principles and Adaptations 395

Target exercise oxygen consumption (mL·kg−1·min−1)

= [oxygen consumption reserve (mL·kg−1·min−1) ×

percentage of oxygen consumption reserve (ex￾pressed as a decimal)] + resting oxygen consump￾tion (mL·kg−1·min−1)

or

TExV.

O2

= (V.

O2

R × %V.

O2

R) + V

.

O2

rest

13.6

Use these steps to calculate training intensity with this

method:

1. Choose the desired intensity of the workout.

2. Use Table 13.3 to fi nd the %V.

O2

R for the desired

exercise intensity.

3. Multiply the percentage (as a decimal) of the desired

intensity times the V.

O2

max.

4. Add the resting oxygen consumption to the obtained

values. Note that this may be an individually measured

value or the estimated 3.5 mL·kg−1·min−1 that repre￾sents 1 metabolic equivalent (MET).

5. Because oxygen drifts, as does heart rate, it is best to

use a target range.

Thus, a HR of 125 b·min−1 represents 40% of HRR

and an HR of 146 b·min−1 represents 59% of HRR.

So, in order to be exercising between 40% and 59%

of HRR, a moderate workload, this individual should

keep her heart rate between 125 and 146 b·min−1.

Example (continued)

This heart rate range (125−146 b·min−1), although still

moderate, is different from the one calculated by using

%HRmax (106−133 b·min−1) because the resting heart

rate is considered in the HRR method.

Work through the problem presented in the Check

Your Comprehension 1 box, paying careful attention to the

infl uence of resting heart rate when determining the train￾ing heart rate range using the HRR (Karvonen) method.

CHECK YOUR COMPREHENSION 1

Calculate the target HR range for a light workout for

two normal-weight individuals, using the %HRmax

and %HRR methods and the following information.

Age RHR

Lisa 50 62

Susie 50 82

Check your answer in Appendix C.

HRmax declines in a rectilinear fashion with advancing

age in adults. Thus, the heart rate needed to achieve a

given intensity level, calculated by either the HRmax or

the HRR method, decreases with age. Figure 13.2 exem￾plifi es these decreases for light, moderate, and heavy exer￾cise using the %HRR method and the expected benefi ts

within each range from age 20 to 70 years.

Oxygen Consumption/%V.

O2

R Methods

In a laboratory setting where an individual has been tested

for and equipment is available for monitoring V.

O2

dur￾ing training, %V.

O2

R may be used to prescribe exercise

intensity. Oxygen reserve is parallel to HRR in that it is

the difference between a resting and a maximal value. It is

calculated according to the formula:

13.5 Oxygen consumption reserve (mL·kg−1·min−1) =

maximal oxygen consumption (mL·kg−1·min−1) –

resting oxygen consumption (mL·kg−1·min−1)

or

V

.

O2

R = V.

O2

max - V.

O2

rest

Target exercise oxygen consumption is then deter￾mined by the equation:

Age (yr)

Health benefits

Light

Moderate

Hard

20%

HRR

40%

HRR

60%

HRR

20 30 40 50 60 70

HR (b·min–1) 180

170

160

150

140

130

120

110

100

90

85%

HRR

Very light

Health benefits

Health & fitness

benefits

Health & fitness

benefits

Health & fitness

benefits

Very hard

FIGURE 13.2. Age-Related Changes in Training Heart

Rate Ranges Based on HRR (Karvonen) Method.

Note: Calculations are based on RHR = 80 b·min−1, HRmax =

220 − age.

Plowman_Chap13.indd 395 lowman_Chap13.indd 395 11/6/2009 9:04:18 PM 1/6/2009 9:04:18 PM

396 Cardiovascular-Respiratory System Unit

either %HRmax or %HRR when prescribing exercise

intensity for children and adolescents, and not make any

equivalency assumption with %V.

O2

.

Table 13.4 shows how long one can run at a specifi c

percentage of maximal oxygen consumption. The Check

Your Comprehension 2 box provides an example of how

this information can be used in training and competi￾tion. Take the time now to work through the situation

described in the box.

CHECK YOUR COMPREHENSION 2

Four friends meet at the track for a noontime workout.

Their physiological characteristics are as follows. (The

estimated V.

O2

max values have been calculated from a

1-mi running test.)

Individual Age (yr)

Estimated V.

O2

max

(mL·kg−1·min−1)

Resting HR

(b·min−1)

Janet 23 52 60

Juan 35 64 48

Mark 22 49 64

Gail 28 56 58

The following oxygen requirements have been calcu￾lated for a given speed based on the equations that

are presented in Appendix B.

Speed (mph)

Oxygen Requirement

(mL·kg−1·min−1)

4 27.6

5 30.3

6 35.7

7 41.0

8 46.4

9 51.7

The friends wish to run together in a moderate workout.

Assume temperate weather conditions.

1. At what speed should they be running?

2. What heart rate should be achieved by each runner

at that pace?

Check your answers with the ones provided in

Appendix C.

Rating of Perceived Exertion Methods

The third way exercise intensity can be prescribed is

by a subjective impression of overall effort, strain, and

fatigue during the activity. This impression is known as

a rating of perceived exertion. Perceived exertion is

typically measured using either Borg 6–20 RPE scale or

the revised 0−10+ Category Ratio Scale (Borg, 1998).

Basing the intensity of a workout on %V.

O2

R is not

very practical because most people do not have access to

the needed equipment. However, the technique can be

modifi ed for individuals who wish to use it. First, one

can use the formula in Appendix B (The Calculation of

Oxygen Consumed Using Mechanical Work or Speed of

Movement) to solve for the workload (velocity of level

or inclined walking or running; resistance for arm or leg

cycling; height or cadence for bench stepping). Then, the

prescription can be based on minutes per mile, cadence of

stepping at a particular height, or load setting at a specifi c

revolutions-per-minute pace. Because the oxygen cost of

submaximal exercise is higher for children and changes as

they age and grow, this technique is rarely used for chil￾dren (Strong et al., 2005).

A second practical use of the V.

O2

R approach is based

on the direct relationship between heart rate and oxygen

consumption. Look closely again at Table 13.3. Note that

the column for %V.

O2

R is also the column for %HRR;

that is, any given %HRR has an equivalent %V.

O2

R in

adults. For example, an adult who is working at 50%

HRR is also working at 50% V.

O2

R. Therefore, heart

rate can be used to estimate oxygen consumption when

an individual is training or competing. The equivalency

between %V.

O2

R and %HRR has been demonstrated

experimentally in both young and older adult males and

females, and for the modalities of cycle ergometry and

treadmill walking and running (Swain, 2000).

Although there is also a rectilinear relationship

between %HRR and %V.

O2

R in children and adolescents,

this relationship is not the same as for adults. In children

and adolescents, the two percentages are not equal. In

a recent study, 50–85%V.

O2

R was found to equate with

60–89% HRR in boys and girls 10–17 years of age (Hui and

Chan, 2006). Therefore, it is probably best to simply use

TABLE 13.4 Time a Selected

%V.

O2

max Can Be

Sustained

During Running

%V.

O2

max Time (min)

100.00 8–10

97.5 15

90 30

87.5 45

85 60

82.5 90

80 120–210

Source: Daniels, J., & J. Gilbert: Oxygen Power: Performance Tables

for Distance Runners. Tempe, AZ: Author (1979).

Plowman_Chap13.indd 396 lowman_Chap13.indd 396 11/6/2009 9:04:19 PM 1/6/2009 9:04:19 PM

CHAPTER 13 • Cardiorespiratory Training Principles and Adaptations 397

if an individual normally works out at 75% HRmax on

land, the prescription for an equivalent workout in the

water should be 65% HRmax. Another way to achieve

the adjustment, if an estimated HRmax is used, is to

start with 205 b·min−1 minus age rather than 220 b·min−1

minus age. Either of these changes should effectively

reduce the RPE as well.

Regardless of the method chosen to prescribe exercise

intensity, always consider three factors:

1. Exercise intensity should generally be prescribed

within a range. Many activities require different lev￾els of exertion throughout the activity. This is par￾ticularly true of games and athletic activities, but it

also applies to activities like jogging and bicycling, in

which changes in terrain can greatly affect exertion. In

addition, a range allows for cardiovascular and oxygen

consumption drifts during prolonged exercise.

2. Exercise intensity must be considered in conjunction

with duration and frequency.

a. Intensity cannot be prescribed without regard to

duration. These two variables are inversely related:

In general, the more intense an activity is, the

shorter it should be.

b. The appropriate intensity of exercise also depends

on the individual’s fi tness level and, to some

extent, the point within his or her fi tness program.

Table 13.5 presents and compares both scales. The RPE

scale is designed so that these perceptual ratings rise in

a rectilinear fashion with heart rate, oxygen consump￾tion, and mechanical workload during incremental

exercise; thus, it is the primary scale used for cardio￾vascular exercise prescription (Table 13.3). The CR-10

scale increases in a positively accelerating curvilinear

fashion and closely parallels the physiological responses

of pulmonary ventilation and blood lactate. Chapter 5

describes the use of these scales for metabolic exercise

prescription.

Both the Borg RPE and the CR-10 scales are intended

for use with postpubertal adolescents and adults.

Because children (~6–12 yr) have diffi culty consistently

assigning numbers to words or phrases to describe their

exercise-related feelings, Robertson et al. (2002) devel￾oped the Children’s OMNI Scale of Perceived Exertion.

The OMNI Scale uses numerical, pictorial, and verbal

descriptors. The original scale, depicted in Figure 13.3,

was validated for cycling activity. Since then, variations

have been developed for walking/running (Utter et al.,

2002) and stepping (Robertson et al., 2005). Children

have been shown to be able to self-regulate their cycling

exercise intensity using the OMNI Scale (Robertson

et al., 2002). In addition, observers can determine

children’s exercise intensity using the OMNI Scale

( Robertson et al., 2006). This could be very helpful for

teachers.

The classifi cation of exercise intensity and the cor￾responding relationships among %HRmax, %V.

O2

R,

%HRR, and RPE presented in Table 13.3 have been

derived from and are intended for use with land-based

activities in moderate environments.

Whether a water activity is performed horizontally,

as in swimming, or vertically, as in running or water

aerobics, postural and pressure changes shift the blood

volume centrally and cause changes in blood pressure,

cardiac output, resistance, and respiration. Although the

magnitude of changes in the cardiovascular system var￾ies considerably among individuals, the most consistent

changes are lower submaximal HR (8–12 b·min−1) at any

given V.

O2

, a lower HRmax (~15 b·min−1), and a lower

V

.

O2

max when exercise is performed in the water. A

greater reliance on anaerobic metabolism is evident, and

the RPE is higher in water than at the same workload

on land (Svedenhag and Seger, 1992). The lower HR is

probably a compensation for the increased stroke vol￾ume (SV) when blood is shifted centrally. As a result, the

HR prescription should be about 10% lower for water

workouts than for land-based workouts. For example,

TABLE 13.5 Scales for Ratings of

Perceived Exertion

RPE Scale CR-10 Scale

6 0.0

7 Very, very light 0.0

8 0.5 Just noticeable

9 Very light 1.0 Very weak

10 1.5

11 Fairly light 2.0 Light/weak

12 3.0 Moderate

13 Somewhat hard 3.5

4.0 Somewhat strong

14 4.5

5.0

15 Hard 5.5

6.0

16 6.5 Very strong

7.0

17 Very hard 7.5

8.0

18 9.0

19 Very, very hard 10.0 Extremely strong

20 10+

(~r12) Highest possible

Rating of Perceived Exertion A subjective impres￾sion of overall physical effort, strain, and fatigue

during acute exercise.

Plowman_Chap13.indd 397 lowman_Chap13.indd 397 11/6/2009 9:04:20 PM 1/6/2009 9:04:20 PM

398 Cardiovascular-Respiratory System Unit

Duration

As shown in Figure 13.1B, improvements in V.

O2

max

can be achieved when exercise is sustained for dura￾tions of 15–45 minutes (Wenger and Bell, 1986). Slightly

greater improvements are achieved from longer sessions

(35–45 min) than from shorter sessions (either 15–25 or

25–35 min). Indeed, greater improvements in V.

O2

max

can be achieved if the sessions are long (35–45 min) and

the intensity is moderate to heavy (50–90%) than if the

Individuals should begin an exercise program at a

low exercise intensity and gradually increase the

intensity in a steploading progression until the

desired level is achieved.

3. Using heart rate or perceived exertion to monitor

training sessions, rather than merely time over dis￾tance, allows the infl uence of weather, terrain, sur￾faces, and the way the individual is responding to be

taken into account when assessing the person’s adapta￾tion to a training program.

0

Not tired

at all

2

A little

tired

4

Getting

more tired

10

Very, very

tired

6

Tired

8

Really

tired

1

3

5

7

9

FIGURE 13.3. Children’s OMNI Scale of Perceived Exertion.

Source: Robertson, R. J., F. L. Goss, N. F. Boer, et al.: Children’s OMNI Scale of Perceived Exertion: Mixed gender

and race validation. Medicine and Science in Sports and Exercise. 32(3):452–458 (2000). Reprinted with Permission.

FOCUS ON

APPLICATION

Ratings of Perceived Exertion and Environmental

Conditions

atings of perceived exertion

(RPE) is a useful, common way

to assess exercise intensity. Note,

however, that the estimation of RPE

(when exercisers are asked how hard

they feel they are exercising) and

actual physiological responses to

exercise are affected by environmen￾tal conditions. Both HR and RPE are

higher when exercise is performed

in a hot environment (or while

wearing clothing that interferes

with heat dissipation) compared to

a thermoneutral environment. The

relationship between HR and RPE

is also affected by environmental

conditions. At any given RPE, HR

is 10–15 b·min−1 higher in the heat

(Maw et al., 1993). When exercisers

are instructed to produce a given

exercise intensity based on a specifi c

RPE, they usually automatically

adjust the exercise intensity to envi￾ronmental conditions. For example,

running at 8 min·mi−1 in thermal

neutral conditions may elicit an RPE

estimation of 13. However, in hot

humid conditions, an individual may

only run at 9 minute mi−1 at an RPE

of 13.

CLINICALLY RELEVANT

R

Plowman_Chap13.indd 398 lowman_Chap13.indd 398 11/6/2009 9:04:20 PM 1/6/2009 9:04:20 PM

CHAPTER 13 • Cardiorespiratory Training Principles and Adaptations 399

not meaningful if exercise participation is increased from

4 to 5 days a week. Although the graph in Figure 13.1C

reveals that there is the potential for further improvement

in V.

O2

max if a sixth day of training is added, a sixth day

is not generally recommended for those pursuing fi tness

goals because of a higher incidence of injury and fatigue.

The optimal frequency for improving V.

O2

max for all

intensities appears to be 4 d·wk−1.

The ACSM recommendation for healthy individuals

is a frequency of 3–5 d·wk−1. However, individuals at very

low fi tness levels may start a program of only 2 d·wk−1

if they are attempting to meet the ACSM intensity

and duration guidelines. Athletes in training may train

6 d·wk−1 as a way of increasing their total training vol￾ume. In this case, “easy” and “hard” days should be inter￾spersed within most microcycles. Cross-training may also

be employed.

Individualization

Fitness programs should be individualized for partici￾pants. Not only do individual goals vary, but individu￾als also respond to and adapt to exercise differently. One

of the major determinants of the individual’s response is

genetics. Another major determinant is the initial fi tness

level. Figure 13.1D clearly shows that independent of fre￾quency, intensity, or duration, the greatest improvements

in V.

O2

max occur in individuals with the lowest initial fi t￾ness level. Thus, both absolute and relative increases in

V

.

O2

max are inversely related to one’s initial fi tness level.

Although improvements in V.

O2

max are smallest in highly

fi t (HF) individuals, at this level, small changes may have

a signifi cant infl uence on performance because many ath￾letic events are won by fractions of a second.

The initial fi tness level generalization also applies to

health benefi ts. Health benefi ts are greatest when a per￾son moves from a low-fi tness (LF) to a moderately fi t cat￾egory. Most sedentary individuals can accomplish this if

they participate in a regular, low- to moderate-endurance

exercise program (Haskell, 1994).

Rest/Recovery/Adaptation

Training programs can be divided into initial, improve￾ment, and maintenance stages. The initial stage

usually lasts 1–6 weeks, although this varies consid￾erably among individuals. This stage should include

low-level aerobic activities that cause a minimum of

muscle soreness or discomfort. It is often prudent

to begin an exercise program at an intensity lower

than the desired exercise range (40–60% HRR). The

aerobic exercise session should last at least 10 min￾utes and gradually become longer. For individu￾als at very low levels of fi tness, a discontinuous or

interval-format training program may be warranted,

using several repetitions of exercise, each lasting

sessions are short (25–35 min) and the intensity is very

hard to maximal (90–100%). Apparently, the total volume

of work is more important in determining cardiorespi￾ratory adaptations than either intensity or duration con￾sidered individually. This is good news, because the risk

of injury is lower in moderate-intensity, long-duration

activity than in high, near maximal, short-duration activ￾ity; and the compliance rate is higher. Thus, most adult

fi tness programs should emphasize moderate- to heavy￾intensity workouts (55–89% HRmax; 40–84% HRR or

V

.

O2

max) for a duration of 20–60 minutes (American Col￾lege of Sports Medicine, 1998, 2006).

This does not mean that exercise sessions less than

20 minutes are not valuable for V.

O2

max or health ben￾efi ts or that the 20 minutes must be accumulated dur￾ing one exercise session. An accumulated 30 minutes

of activity spread throughout the day may be suf￾fi cient to achieve health benefi ts. For example, two

groups of adult males participated in a walk-jog pro￾gram at 65–75% HRmax, for 5 d·wk−1 for 8 weeks

(De Busk et al., 1990). The only variation was that one

group did the 30-minute workout continuously while

the other had 10-minute sessions at three different

times during the day. Both groups increased the pri￾mary fi tness variable V.

O2

max signifi cantly (although the

30-minute consecutive group did so to a greater extent)

and lost equal amounts of weight—an important health

benefi t.

Thus, for individuals who claim that they do not have

time to exercise, suggesting a 10-minute brisk walk in the

morning (perhaps to work or walking the kids to school),

at noon (to a favorite restaurant and back), and in the eve￾ning (perhaps walking to the video store or taking the

dog for a walk) might make it easier to achieve a total of

30 minutes of activity. The benefi t of split sessions is par￾ticularly important for those in rehabilitation programs.

An injured person may simply not be able to exercise for

a long period, while short bouts may be possible spread

throughout the day. In this case, the exercise prescrip￾tion can start with multiple (4–10 per day) sessions lasting

2–5 minutes each and build by decreasing the number

of daily sessions and increasing the duration of each

( American College of Sports Medicine, 2006).

Frequency

If the total work done or the number of exercise sessions

is held constant, there is basically no difference in the

improvement of V.

O2

max over 2, 3, 4, or 5 days (Pollock,

1973). However, when these conditions are not adhered

to, there does seem to be an advantage to more frequent

training. As Figure 13.1C shows, the improvement in

V

.

O2

max is proportional to the number of training ses￾sions per week (Wenger and Bell, 1986). In general, train￾ing fewer than 2 d·wk−1 does not result in improvements

in V.

O2

max. Likewise, further improvement in V.

O2

max is

Plowman_Chap13.indd 399 11/6/2009 9:04:20 PM

400 Cardiovascular-Respiratory System Unit

performance is achieved. Each time an exercise program

is modifi ed, there will be a period of adaptation that may

be followed by further progression, if desired.

Maintenance

Athletes often vary their training levels according to a

general preparation phase (off-season), specifi c prepa￾ration phase (preseason), competitive phase (in season),

and transition phase (active rest). In transition and com￾petitive phases, they can shift to a maintenance schedule.

For rehabilitation and fi tness participants, maintenance

typically begins after the fi rst 4–8 months of train￾ing. Reaching the maintenance stage indicates that the

individual has achieved a personally acceptable level of

cardiorespiratory fi tness and is no longer interested in

increasing the conditioning load (American College of

Sports Medicine, 2006).

After attaining a desired level of aerobic fi tness,

this level can be maintained either by continuing the

same volume of exercise or by decreasing the volume of

training, as long as intensity is maintained. Figure 13.4

shows the results of research that investigated changes

in V.

O2

max with 10 weeks of relatively intense interval

training and a subsequent 15-week reduction in training

frequency (13.4A), duration (13.4B), or intensity (13.4C)

(Hickson and Rosenkoetter, 1981; Hickson et al., 1982,

1985). When training frequency was reduced from

6 d·wk−1 to 4 or 2 d·wk−1 and intensity and duration

were held constant, training-induced improvements in

V

.

O2

max were maintained. Similarly, when training dura￾tion was reduced from 40 to 26 or 13 minutes, improve￾ments in V.

O2

max were maintained or continued to

improve. However, when intensity was reduced by two

thirds, improvements in V.

O2

max were not maintained.

These results indicate that intensity plays a primary role

in maintaining cardiovascular fi tness. Thus, although the

total volume of exercise is most important for attaining a

given fi tness level, intensity is most important for main￾taining the achieved fi tness level. During the maintenance

phase of a training program, cross-training is particularly

benefi cial, especially on days when a high-intensity work￾out is not called for.

Retrogression/Plateau/Reversibility

Sometimes, an individual in training may fail to improve

(plateau) or exhibit a performance or physiological

decrement (retrogression), despite progression of the

training program. When such a pattern occurs, it is

important to check for other signs of overtraining (see

Chapters 1 and 22). A shift in training emphasis or the

inclusion of more easy days is warranted. Remember

that a reduction in the frequency of training does not

necessarily lead to detraining and may actually enhance

performance.

2–5 minutes (American College of Sports Medicine,

2006). Rest periods between the intervals reduce the

overall stress on the individual by allowing intermit￾tent recovery. Frequency may vary from short, light

daily activity to longer exercise sessions two or three

times per week. Adaptation occurs during the off days.

An important part of this stage is helping the individual

achieve the “habit” of exercise and orthopedically adapt

to workouts. Soreness, discomfort, and injury should

be avoided to encourage the individual to continue.

During the improvement stage, signifi cant changes

in physiological function indicate that the body is

adapting to the stress of the training program. Again,

the individual adapts during rest days when the body

is allowed to recover. Adaptation has occurred when

the same amount of work is accomplished in less time,

when the same amount of work is accomplished with

less physiological (homeostatic) disruption, when the

same amount of work is accomplished with a lower per￾ception of fatigue or exertion, or when more work is

accomplished. Once the body has adapted to the stress

of exercise, progression is necessary to induce additional

adaptations, or maintenance is required to preserve the

adaptations.

Progression

Once adaptation occurs, the workload must be increased

for further improvement to occur. The workload can be

increased by manipulating the frequency, intensity, and

duration of the exercise. Increasing any of these vari￾ables effectively increases the volume of exercise and

thus provides the overload necessary for further adapta￾tion. The rate of progression depends on the individual’s

needs or goals, fi tness level, health status, and age but

should always be instituted in a steploading fashion of

2–3 weeks of increase followed by a decrease for recovery

and regeneration before increasing the training volume

again.

The improvement stage of a training program

typically lasts 4–8 months and is characterized by

relatively rapid progression. For an individual with a

low fitness level, the progression from a discontinu￾ous activity to a continuous activity should occur first.

Then the duration of the activity should be increased.

This increase in duration should not exceed 20% per

week until 20–30 minutes of moderate- to vigorous￾intensity activity can be completed, and 10% per week

thereafter. Frequency can then be increased. Intensity

should be the last variable to be increased. Adjust￾ments of no more than 5% HRR every 6 exercise ses￾sions (1.5–2 wk) are well tolerated (American College

of Sports Medicine, 2006).

The principles of adaptation and progression

are intertwined. Adaptation and progression may be

repeated several times until the desired level of fi tness or

Plowman_Chap13.indd 400 lowman_Chap13.indd 400 11/6/2009 9:04:21 PM 1/6/2009 9:04:21 PM

CHAPTER 13 • Cardiorespiratory Training Principles and Adaptations 401

If training is discontinued for a signifi cant period

of time, detraining will occur. This principle, often

referred to as the reversibility concept, holds that when

a training program is stopped or reduced, body systems

readjust in accordance with the decreased physiologi￾cal stimuli. Increases in V.

O2

max with low to moderate

exercise programs are completely reversed after train￾ing is stopped. Values of V.

O2

max decrease rapidly dur￾ing a month of detraining, followed by a slower rate of

decline during the second and third months (Bloomfi eld

and Coyle, 1993).

Warm-Up and Cooldown

A warm-up period allows the body to adjust to the car￾diovascular demands of exercise. At rest, the skeletal

muscles receive about 15–20% of the blood pumped

from the heart; during moderate exercise, they receive

approximately 70%. This increased blood fl ow is impor￾tant for warming the body since the blood carries heat

from the metabolically active muscle to the rest of the

body.

A warm-up period of 5–15 minutes should precede

the conditioning portion of an exercise session (American

College of Sports Medicine, 2006). The warm-up should

gradually increase in intensity until the desired intensity

of training is reached. For many activities, the warm-up

period simply continues into the aerobic portion of the

exercise session. For example, if an individual is going for

a noontime run and wants to run at an 8 min·mi−1 pace,

he may begin with a slow jog for the fi rst few minutes

(say a 10 min·mi−1 pace), increase to a faster pace (say a

9 min·mi−1 pace), and then proceed to the desired pace

(the 8 min·mi−1 pace).

A warm-up period has the following benefi cial effects

on cardiovascular function.

• It increases blood fl ow to the active skeletal muscles.

• It increases blood fl ow to the myocardium.

• It increases the dissociation of oxyhemoglobin.

• It causes sweating, which plays a role in temperature

regulation.

• It may reduce the incidence of abnormal rhythms in

the heart’s conduction system (dysrhythmias), which

can lead to abnormal heart function (American College

of Sports Medicine, 2006; Barnard et al., 1973).

A cooldown period of 5–15 minutes should follow

the conditioning period of the exercise session. The

cooldown period prevents venous pooling by keeping

the muscle pump active and thus may reduce the risk of

postexercise hypotension (and possible fainting) and dys￾rhythmias (American College of Sports Medicine, 2006).

A cooldown also facilitates heat dissipation and promotes

a more rapid removal of lactic acid and catecholamines

from the blood.

20

10

Training Reduced training

10 15

(10 weeks) (15 weeks)

5 10 5

0

Training Reduced training

10 15

(10 weeks) (15 weeks)

5 10 5

Training Reduced training

Reduced frequency

Reduced duration

Reduced intensity

2/3 reduction

26 min

4 days

2 days

13 min

10 15

(10 weeks) (15 weeks)

5 10 5

C

B

A

% Change in pretraining VO max 2 % Change in pretraining VO max 2 % Change in pretraining VO max 2 20

10

0

20

10

0

1/3 reduction

FIGURE 13.4. Effects of Reducing Exercise Fre￾quency, Intensity, and Duration on Maintenance

of V

.

O2

max.

A: Improvements in V.

O2

max during 10 weeks of training (bicy￾cling and running) for 40 minutes a day, 6 days a week were

maintained when training intensity and duration were main￾tained with a reduction in frequency from 6 days a week to 4

or even 2 d·wk−1. B: V

.

O2

max was maintained when frequency

of training and intensity were maintained with a reduction of

training duration to 13 minutes. V.

O2

max continued to improve

when training duration was reduced to 26 minutes. C: V

.

O2

max

was maintained when frequency and duration were maintained

and intensity was reduced by one third. V.

O2

max was not main￾tained when training was reduced by two thirds.

Sources: Hickson and Rosenkoetter (1981), Hickson et al.

(1982, 1985).

Plowman_Chap13.indd 401 lowman_Chap13.indd 401 11/6/2009 9:04:21 PM 1/6/2009 9:04:21 PM

402 Cardiovascular-Respiratory System Unit

publicizing those health benefi ts and recommending

levels of activity that are intended to be nonintimidating

for currently sedentary individuals. The SGR recom￾mends that individuals of all ages accumulate a minimum

30 minutes of physical activity of moderate intensity

on most, if not all, days of the week. This baseline rec￾ommendation was intended primarily for previously

sedentary individuals who are either unable or unwill￾ing to do more formal exercise. The report encourages

individuals who already include moderate activity in their

daily lives to increase the duration of their moderate activ￾ity and/or include vigorous activity 3–5 d·wk−1 to obtain

additional health and fi tness benefi ts. Two sets of physi￾cal activity and public health guidelines, one for healthy

adults 18–65 years and the other for older or clinically

TRAINING PRINCIPLES AND PHYSICAL

ACTIVITY RECOMMENDATIONS

Much evidence has been compiled that demonstrates

the health-related benefi ts of moderate physical activ￾ity, including reduced incidence of cardiac events, stroke,

hypertension, type 2 diabetes, some types of cancer,

obesity, depression, and anxiety. This evidence is sum￾marized in The Surgeon General’s Report (SGR) on

Physical Activity and Health (U.S. Department of Health

and Human Services, 1996) and is discussed in detail in

Chapter 15. The SGR (Table 13.1) is an important pub￾lic health statement that recognizes the health benefi ts

associated with moderate levels of physical activity and

encourages increased activity among Americans by widely

FOCUS ON

APPLICATION

Manipulation of Training Overload in a Taper

P eaking for performance often

involves manipulating the

training principles of specifi city,

overload, and maintenance within a

periodization plan. This is exempli￾fi ed by a study in which 18 male

and 6 female distance runners were

pretested, matched, and then

divided into three groups. The run

taper group systematically reduced

its weekly training volume to 15%

of its previous training volume over

a 7-day period, performing 30% of

the calculated reduced training

distance on day 1, and then 20%,

15%, 12%, 10%, 8%, and 5% on

each succeeding day. Training con￾sisted of 400-m intervals at close to

5-km pace (~100% V.

O2

peak), result￾ing in an HR of 170–190 b·min−1

with recovery to 100–110 b·min−1

before the next interval. The cycle

taper group performed approxi￾mately the same number of intervals

for the same duration as paired

athletes in the run taper group, at

the same work and recovery heart

rates. The control group continued

normal training, of which 6–10% of

the weekly training distance was

interval/fartlek work. All subjects

participated in a 10-minute

submaximal treadmill run, an incre￾mental treadmill test to volitional

fatigue in which the grade remained

constant at 0% and the speed

increased, and a 5-km time trial on

the treadmill.

At the same absolute speed dur￾ing the submaximal run, the run

taper group (and seven of the eight

individual runners) exhibited a 5%

reduction (2.4 mL·kg−1·min−1) in

oxygen consumption and a decrease

of 7% (0.9 kcal·min−1) in calculated

energy expenditure. No changes

were evident in either the cycle

taper or the control group. Both

maximal treadmill speed (2%) and

total exercise time (4%) increased

for the run taper group without

concomitant increase in V.

O2

max or

HRmax. No changes occurred in any

maximal value for the cycle run or

control groups. The run taper group

(all eight individuals) signifi cantly

improved 5-km performance by a

mean of 2.8% ± 0.4%, or an average

of almost 30 seconds. No improve￾ment in performance was seen in

either the cycle run or the control

group.

These results clearly demonstrate

the benefi ts of a 7-day taper in

which intensity is maintained, train￾ing volume drastically reduced, and

specifi city of training utilized. Of

the variables measured, the most

likely explanation for the improved

5-km performance was the increase

in submaximal running economy

(decreased submaximal oxygen and

energy cost). Note, however, that

all three groups maintained their

V

.

O2

max values. This cross-training

benefi t exhibited by the cycle taper

group is particularly important.

Distance runners often have nag￾ging injuries. These results imply

that a non–weight-bearing taper

may be used in such cases and allow

the runner to possibly heal (or at

least not aggravate an injury) while

maintaining cardiovascular fi tness.

Performance enhancement, however,

appears to require mode specifi city

during the taper.

Source:

Houmard, J. A., B. K. Scott, C. L. Justice, &

T. C. Chenier: The effects of taper on per￾formance in distance runners. Medicine and

Science in Sports and Exercise. 26(5):624–

631 (1994).

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