| Percent
HRR Method
A more accurate way to calculate THR is the percent HRR method.
The range from 60 to 90 percent HRR is the THR range in which people should exercise
to improve their CR fitness levels. If a soldier knows his general level of CR
fitness, he can determine which percentage of HRR is a good starting point for
him. For example, if he is in excellent physical condition, he could start at
85 percent of his HRR; if he is in reasonably good shape, at 70 percent HRR; and,
if he is in poor shape, at 60 percent HRR.
Most CR workouts should be conducted
with the heart rate between 70 to 75 percent HRR to attain, or maintain, an adequate
level of fitness. Soldiers who have reached a high level of fitness may derive
more benefit from working at a higher percentage of HRR, particularly if they
cannot find more than 20 minutes for CR exercise. Exercising at any lower percentage
of HRR does not give the heart, muscles, and lungs an adequate training stimulus.
Before anyone begins aerobic training, he should know his THR (the heart rate
at which he needs to exercise to get a training effect).
The example below
shows how to figure the THR by using the resting heart rate (RHR) and age to estimate
heart rate reserve (HRR). A 20-year-old male soldier in reasonably good physical
shape is the example.
STEP 1: Determine the MHR by subtracting the soldier's
age from 220.
FORMULA
220 - age = MHR
(GIVEN)
CALCULATION
220 - 20 = 200 BPM
STEP 2: Determine the RHR in
beats per minute (BPM) by counting the resting pulse for 30 seconds, and multiply
the count by two. A shorter period can be used, but a 30-second count is more
accurate. This count should be taken while the soldier is completely relaxed and
rested. How to determine the heart rate is described below. Next, determine the
heart rate reserve (HRR) by subtracting the RHR from the estimated MHR. If the
soldier's RHR is 69 BPM, the HRR is calculated as shown here.
FORMULA
MHR - RHR = HRR
CALCULATION
200 BPM - 69 BPM = 131 BPM
STEP 3: Calculate the THR based on 70 percent of the HRR (a percentage based on
a good level of CR fitness).
FORMULA
(% x HRR) + RHR = THR
CALCULATION
(0.70 x 131) + 69 BPM = 160.7 BPM
As shown, the percentage
(70 percent in this example) is converted to the decimal form (0.70) before it
is multiplied by the HRR. The result is then added to the resting heart rate (RHR)
to get the THR. Thus, the product obtained by multiplying 0.70 and 131 is 91.7.
When 91.7 is added to the RHR of 69, a THR of 160.7 results. When the calculations
produce a fraction of a heart beat, as in the example, the value is rounded off
to the nearest whole number. In this case, 160.7 BPM is rounded off to give a
THR of 161 BPM. In summary, a reasonably fit 20-year-old soldier with a resting
heart rate of 69 BPM has a training heart rate goal of 161 BPM. To determine the
RHR, or to see if one is within the THR during and right after exercise, place
the tip of the third finger lightly over one of the carotid arteries in the neck.
These arteries are located to the left and right of the Adam’s apple. (See Figure
2-1A.) Another convenient spot from which to monitor the pulse is on the radial
artery on the wrist just above the base of the thumb. (See Figure 2-lB.) Yet another
way is to place the hand over the heart and count the number of heart beats. (See
Figure 2-1 C.)
During aerobic exercise, the body will usually have reached
a "Steady State" after five minutes of exercise, and the heart rate
will have leveled off. At this time, and immediately after exercising, the soldier
should monitor his heart rate.
He should count his pulse for 10 seconds, then
multiply this by six to get his heart rate for one minute. This will let him determine
if his training intensity is high enough to improve his CR fitness level.
For example, use the THR of 161 BPM figured above. During the 10- second period,
the soldier should get a count of 27 beats (161/6= 26.83 or 27) if he is exercising
at the right intensity. If his pulse rate is below the THR, he must exercise harder
to increase his pulse to the THR. If his pulse is above the THR, he should normally
exercise at a lower intensity to reduce the pulse rate to the prescribed THR.
He should count as accurately as possible, since one missed beat during the 10-second
count, multiplied by six, gives an error of six BPM.
A soldier who maintains his THR throughout a 20- to 30-minute exercise period
is doing well and can expect improvement in his CR fitness level. He should check
his exercise and post exercise pulse rate at least once each workout. If he takes
only one pulse check, he should do it five minutes into the workout.
Figure
2-2 is a chart that makes it easy to determine what a soldier’s THR should be
during a 10-second count. Using this figure, a soldier can easily find his own
THR just by knowing his age and general fitness level. For example, a 40-year-old
soldier with a low fitness level should, during aerobic exercise, have a THR of
23 beats in 10 seconds. He can determine this from the table by locating his age
and then tracking upward until he reaches the percent HRR for his fitness level.
Again, those with a low fitness level should work at about 60 percent HRR and
those with a good fitness level at 70 percent HRR. Those with a high level of
fitness may benefit most by training at 80 to 90 percent HRR.
Another way
to gauge exercise intensity is “perceived exertion.” This method relies on how
difficult the exercise seems to be and is described in Appendix G.
 TIME
Time, or duration, refers to how long one exercises. It is inversely related to
intensity. The more intense the activity, the shorter the time needed to produce
or maintain a training effect; the less intense the activity, the longer the required
duration. To improve CR fitness, the soldier must train for at least 20 to 30
minutes at his THR. TYPE
Only aerobic exercises that require breathing in large volumes of air improve
CR fitness. Worthwhile aerobic activities must involve the use of large muscle
groups and must be rhythmic. They must also be of sufficient duration and intensity
(60 to 90 percent HRR). Examples of primary and secondary exercises for improving
CR fitness are as follows:
PRIMARY
• Running.
• Rowing.
•
Jogging.
• Skiing (cross-country).
• Walking (vigorous).
• Exercising
to music.
• Road marching.
• Rope skipping.
• Bicycling (stationary).
• Swimming.
• Bicycling (road/street).
• Stair climbing.
SECONDARY
(Done with partners or opponents of equal or greater ability.)
• Racquetball
(singles).
• Basketball (full court).
• Handball (singles).
• Tennis
(singles).
The primary exercises are more effective than the secondary
exercises in producing positive changes in CR fitness.
The secondary activities
may briefly elevate the heart rate but may not keep it elevated to the THR throughout
the entire workout.
Every activity has its advantages and disadvantages. Trainers
must weigh these and design programs that fit the unit’s needs. Running
Running enables the body to improve the transport of blood and oxygen to the working
muscles and brings about positive changes in the muscles’ ability to produce energy.
Running fits well into any physical training program ‘because a training effect
can be attained with only three 20-minute workouts per week.
Some soldiers
may need instruction to improve their running ability. The following style of
running is desired. The head is erect with the body in a straight line or slightly
bent forward at the waist. The elbows are bent so the forearms are relaxed and
held loosely at waist level. The arms swing naturally from front to rear in straight
lines. (Cross-body arm movements waste energy. The faster the run, the faster
the arm action.) The toes point straight ahead, and the feet strike on the heel
and push off at the big toe.
Besides learning running techniques, soldiers
need information on ways to prevent running injuries. The most common injuries
associated with PT in the Army result from running and occur to the feet, ankles,
knees, and legs. Proper warm-up and cool-down, along with stretching exercises
and wearing appropriate clothing and well-fitting running shoes, help prevent
injuries. Important information on safety factors and common running injuries
is presented in Chapter 13 and Appendix E.
Failure to allow recovery between
hard bouts of running cannot only lead to overtraining, but can also be a major
cause of injuries. A well-conditioned soldier can run five to six times a week.
However, to do this safely, he should do two things: 1) gradually buildup to running
that frequently; and, 2) vary
the intensity and/or duration of the running
sessions to allow recovery between them. ABILITY
GROUP RUNNING
Traditionally, soldiers have run in unit formations at a
pace prescribed by the PT leader. Commanders have used unit runs to improve unit
cohesion and fitness levels. Unfortunately, too many soldiers are not challenged
enough by the intensity or duration of the unit run, and they do not receive a
training benefit. For example, take a company that runs at a nine-minute-per-mile
pace for two miles. Only soldiers who cannot run two miles in a time faster than
18 minutes will receive a significant training effect. Therefore, in terms of
conditioning, most soldiers who can pass the 2-mile-run test are wasting their
time and losing the chance to train hard to excel. Ability group running (AGR)
is the best way to provide enough intensity so each soldier can improve his own
level of CR fitness.
AGR lets soldiers train in groups of near-equal ability.
Each group runs at a pace intense enough to produce a training effect for that
group and each soldier in it. Leaders should program these runs for specific lengths
of time, not miles to be run. This procedure lets more-fit groups run a greater
distance than the less-fit groups in the same time period thus enabling every
soldier to improve.
The best way to assign soldiers to ability groups is to
make a list, in order, of the unit’s most recent APFT 2-mile-run times. The number
of groups depends on the unit size, number of leaders available to conduct the
runs, and range of 2-mile-run times. A company-sized unit broken down into four
to six ability groups, each with a leader, is best for aerobic training, For activities
like circuits, strength training, and competitive events, smaller groups are easier
to work with than one large group.
Because people progress at different rates,
soldiers should move to faster groups when they are ready. To help them train
at their THR and enhance their confidence, those who have a hard time keeping
up with a group should be placed in a slower group. As the unit’s fitness level
progresses, so should the intensity at which each group exercises. Good leadership
will prevent a constant shifting of soldiers between groups due to lack of effort.
AGR is best conducted at the right intensity at least three times a week. As explained,
the CR system should not be exercised “hard” on consecutive days. If AGR is used
on hard CR training days, unit runs at lower intensities are good for recovery
days. Using this rotation, soldiers can gain the desired benefits of both unit
and ability-group runs. The problem comes when units have a limited number of
days for PT and there is not enough time for both. In this case, unit runs should
seldom, if ever, be used and should be recognized for what they are -- runs to
build unit cohesion.
Leaders can use additional methods to achieve both goals.
The unit can begin in formation and divide into ability groups at a predetermined
release point. The run can also begin with soldiers divided into ability groups
which join at a link-up point. Alternately, ability groups can be started over
the same route in a stagger, with the slowest group first. Linkups occur as each
faster group overtakes slower groups.
With imagination and planning, AGR will
result in more effective training workouts for each soldier. The argument that
ability-group running detracts from unit cohesion is invalid. Good leadership
and training in all areas promote unit cohesion and team spirit; training that
emphasizes form over substance does not.
Continue to
Interval Training
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