Rolul intensitati in dezvoltarea capacitatii de efoer (En)

7/26/2019 Rolul intensitati in dezvoltarea capacitatii de efoer (En)

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IntensityThe training of endurance runners characteristically emphasizes the completion of

long-duration, low- to moderate-intensity efforts, especially during the base or preparation

phase of training, but research reveals that such running has a rather weaj effect on

performance0 related variables and running performance compared with higher-intensity

exertions.Intensity can ve defined as a percent if maximal heart rate or an actual running speed,

but it usually defined as percentage of !" max. when an athlete is said to be running at an

intensity of #0 percent of !"max, it simply means that the runner$s speed is producing an

oxygen consumption rate that is #0 procent of maximum.

Studying the Effects of Intensity

!ne of the first published scientific investigations examining the effects of intensity on

fitness ased theree groups of subjets to train three times a wee% at intensities of either &', (',

or )' precent of maximal heart rate. *ll froups expended the same number of calories per

session, which meant that the lower-intensity groups had to exercise longer per wor%out.

+or%out duration was ,' minutes for the )' percent group, "",' minutes for the (' percent

group, and ' minutes for the &' percent group. !ver a 0-wee% training period, the )' and

(' percent groups raised !"max by about "0 percent, while the &' percent group failed to

improve !"max at all. This study was one of the first to reveal that intensity is a

considerably stronger force than wor%our duration /i.e, total time spent training from the

srabdpoint of improving fitness. 1ote that the (' percent groups trained '0 percent longer

than the )' percent group and yet failed to gain a fitness advantage over the )' percent group.

The &' percent group trained more than twuce as long and didn$t improve !"max at all.

In a subse2uent study, university students trained five times per wee% for " wee%s at a

heart rate of either 0 or (" beats per minute. *t the end of two wee%s, !" max increased

by & percent for the high-intensity group but failed to move upward at all for the lower-

intensity group.3ince then, many studies have revealed that training at relatively higher intensities

produces superior physiological adaptations compared with training at lower levels of effort.

In one study, 0 runners were randomly assigned to one of four training groups4

. long, slow distance training at (0 percent of !"max

". lactate-threshold training at )' percent of maximum heart rate /probably

corresponding to about (& percent of !"max

. high- intensity '5' interval running /i.e., ' seconds of running at #0 to #' 6ercent

of maximal heart rate alternating with ' seconds of recovery at (0 percent of

maximal heart rate

. high- 2uality x interval training /i.e., four wor% intervals, eah consisting of

minutes of running at #0 to #' percent of maximal heart rate after each wor%interval.

*ll four plans resulted in similar total oxygen consumption during training so that total

wor% performed would be roughly e2uivalent between groups7 the wor%outs were conducted

three times a wee% for ) wee%s.

*l the end of the )-wee% period, !"max had increased by ',' percent in the '5'

group and by (," percent in the x group but failed to improve at all in the long, slow

distance group and the lactate-threshold group. 3tro%e volume, or the amount of blood

pumped by the heart per beat, increased by approximately 0 percent in both interval groups

/i.e., '5' and x after ) wee%s but failed to budge in the slow-distance and lactate-

threshold groups. This study is one if many that reveal that higher training intensities produce

greater training responses compared with lower intensities of effort.



Greater Intensity Equals Greater Imporvement

In research conducted by three-time !lympic gold medal winner 8eter 3nell and his

colleagues at the 9niversity of Texas 3outhweastern :uman 8erformance ;enter, well-trained

runners with average !"max values of &,(ml < %g < min participated in a &-wee% study

that initially involved running '0 miles /) %m a wee%s. =or the next 0 wee%s, half of the

runners substituted tempo training twice a wee% for their usual daily runs7 these temposessions involved "# minutes of continuous running at intensities of about (0 to )0 percent of

!"max. The other half substituted two interval sessions per wee% for their usual wor%outs.

>ach interval sessions involved about miles /' %m of wor% intervals, with the intensity of

each interval at #0 to 00 percent of !"max, or about 0? to ? race pace.

*fter the & wee%s, the runners who followed the interval plan improved their )00-

meter times by ." seconds and their 0? times by a full ", minutes. In contrast, the group

that used tempo training boosted )00-meter performance by just &,& seconds and 0? efforts

by , minute. !"max increased by " percent for the higher-intensity interval group but by

only percent for the group using tempo training. !verall, the higher-intensity interval

training produced greater improvements in performance and aerobic capacity than did a

greater volume of lower-intensity wor%.3ince intense training is such a potent producer of running fitness, it follows that the

careful and progressive replacement of moderate-intensity running with higher-speed effort in

an overall training program should produce upswings in fitness and performance. In one

study, experienced '? runners replaced about " percent of their usual moderate-intensity

aerobic running with explosive efforts involving high-speed sprints, bounds, and hopping

drills7 they subse2uently upgraded their '? performance by about percent. In the progress,

these '? runners also enhanced running economy a %ey indicator of endurance-running

capability.

In a separate investigation, experienced, competitive 0? runners added days a wee%

of high-intensity interval training at #0 to #' percent of !"max,or 0? to '? race pace, to

their programs. *s a result, they upgraded #? performances, bolstered endurance during

high-speed running, and decreased plasma lactate concentrations at intensities of )' and #0

percent of !"max, which indicates an underlying improbement in lactate-threshold speed.

In a study that examined the merits of high-volume versus high-intensity training, a

group pf experienced runners replaced )" %ilometers /' mi per wee% of moderate-intensity

running with high0intensity running and cycling. @unning volume was reduced to about 0

wee%ly miles /)%m of hard effort, and three tough cycling sessions were inserted into the

program each wee%. The cycling wor%outs were ' x '4 five '-minute wor% intervals at an

intensity that produced !"max with '-minutes recoveries. Aespite the significant decrease

in running volume, the emphasis on intense running and cycling training led to significantly

faster 0? race times4 *verage 0? cloc%ing improved by ) seconds.

Searching for the Training Threshold

Bany runners believe that there in as exercise intensity that must be exceeded during a

wor%out in order for the session to produce physiological adaptations. The theoretical training

intensity above which adaptation occurs and below which no response in fitness is observed

had sometimes been called the training threshold. Identification of this threshold is of more

than esoteric interest since many runners would li%e to %now whether there is a danger of

dipping too low on the intensity scale during their relatively easy wor%outs.

9nfortunately, scientific research has had a difficult time locating a training threshold

with any degree of precision or unanimity. arious studies have suggested that the threshold

might occur at about '0 percent of !"max7 (' percent of maximal heart rate, which wouldcorrespond with approximately &" percent of !"max7 slightly above &0 percent of the



difference between maximal heart rate and resting heart rate7 or simply at a heart rate of about

0 to '0 eats per minute. This range of results is substantial enough to call the training

threshold concept into 2uestion. In addition, a heart rate of 0 to '0 would correspond with

the highest-possible level of exertion for a runner with a maximal heart rate of ' or so and

yet would represent easy effort for a runner with a maximal heart rate of ""0.

;asting more than a little suspicion on the threshold concept, one study found thatadaptation to training occurred at the extremely light intensity of & percent of !"max, ir

about '' percent of maximal heart rate. !ther studies have noted that adaptation can occur

when training intensity is maintained at just ' percent of !"max. adaptation has also been

documented when exercise intensity is set at a relatively low heart rate of 0 to "0 beats per

minute. It would seem that just moving around- jogging at very slow pace- would produce

physiological change in relatively untrained runners.

1onetheless, it appears that a threshold exists for some runners, particularly those with

a significant training bac%ground. In one study, moderately trained individuals who ordinarily

trained ' minutes per day, three times a wee%, embar%ed on a program involving exercise

durations as great as ',' hours per day /C carried out six times per wee% over an )-wee%

period. The average exercise intensity was an extremely moderate ' percent of !"max, orabout & percent of maximal heart rate. 3ince no training effect /i.e., adaptation was observed

at all after the ) wee%s, it can be assumed that these athletes were below some sort of training

threshold- or else that they were not recovering enough for the adaptations to become

apparent.

3uch studies have am inherent wea%ness in the sense that all of training was conducted

at a specific intensity, after which the involved athletes were chec%ed for adaptations. In the

real world, runners train at a variety of intensities over the course of a wee% or month. *

more-interesting 2uestion would focus on whether lighter days of training really provide

enough stimulus for adaptation to complement the higher-2uality wor% conducted during the

same period. =or example, if a runners is covering 0 miles /& %m total per wee% during

training, with 0 2uality miles /& %m above lactate-threshold speed, is it necessary for the

other 0 miles /) %m to be completed above a certain intensity in a order for increased

fitness to accrue D no study has provided an answer to this basic 2uestion.

The solution to the training threshold paradox may also be that the actual training

response depends to a large extent on the underlying fitness of the individual. 3pecifically,

very fit runners re2uire a high intensity of training to move performance capacity upward,

while less fit individuals may benefit from running that is much more moderate in intensity.

Eeginning runners can benefit a lot from running at an intensity of (0 percent of !"max, for

example, but it is unli%ely that such an intensity would produce major physiological

movements in an experienced runner. 9nfortunately, many elite runners fail to ta%e this

training truism into account and adjust their training include higher and higher volumes ofmoderate- intensity wor% instead of shifting toward gradually increasing amounts of high-

intensity effort.

Determining the Ideal Intensity

@unners have a wide range of intensities from which to choose for their high-2uality

wor%outs. ;an a specific intensity be identified as the most potent producer of running

fitnessD Is there one training intensity that produces the greatest combined improvements in

the %ey predictors of endurance0 running performance- v!"max, running economy, lactate-

threshold speed, and maximal running velocity < as well as in performance itselfD

These are tough 2uestions to answer. !ne could survey the published scientific wor%

in this area and attempt to draw conclusions, but it would be very difficult to compare

different research investigations. 3tudies use runners with different bac%grounds and abilitylevels and subject the runners involved to training regimens that vary in fre2uency, wor%out



duration, volume, and intensity. 1onetheless, a consensus is gradually emerging that the most

productive intensities may be in the range of #' to 00 percent of !"max.

This suggests that v!"max, the minimal running speed that elicits !"max, may be

an extremely beneficial training intensity. In research carried out by =rench physiologist

eroni2ue Eillat, ) experienced runners with high aerobic capacities of (," ml- %g < min

carried out one v!"max wor%out each wee over a wee% period in addition to their usualtraining. The actual v!"max session was ' x 000 meters /& mi at vo"max, with minute

jog recoveries. *fter just the wee%s, vo"max improved by percent, running economy was

enhanced by an extremely impressive & percent, and lactate-threshold speed by percentC in

addition, one of the greatest gains in maximal aerobic capacity ever documented in a study

carried out with experienced, competitive runners resulted from using v!"max as the %ey

training intensity.

3uch findings do ring coaches and runners bac% to the threshold 2uestions4 If 2uality

training is conducted at #' to 00? percent of !"max or at #0 to 00 percent of !"max,

which would be from a 0? pace up to v!"max, what is the minimal intensity for

complementary, easy wor%outsD :ow fast must one light days to nudge %ey performance

variables in the right directionDThe answer is that on easy days, a runner is simply playing the volume game, using

miles or %ilometers rather than intensity to advance fitness. Thus, it probably does not matter

how fast the runner is moving < just covering the miles will produce the desired positive

effect, with most of the gains in running capacity coming from the 2uality efforts in other

days of training. 1ote, though, t&hat the volume game can be overplayed. If a runner is

already covering '0 to (0 miles /)- %m per wee or more, additional easy miles are

unli%ely to have any effect on fitness at all.

Conclusion

@unners, running coaches, and especially proponents of high-volume training models

often suggest that a relatively high volume of moderate-intensity training can produce an

adaptive response similar to the one associated with a lower volume of high-intensity wor%. In

relatively inexperienced and untrained runners, this can sometimes be true. :owever, it is

unli%ely to be the case in experienced and elite runners, who re2uire a steady diet of high

intensities to ma%e the indicators of physiological variables move upward.

* reasonable idea is to %eep trac% of intense volume /i.e., number of miles of

%ilometers run at 0? pace of faster as a percentage of the total volume. !f the number of

miles or %ilometers completed per wee%. If this percent- replacing less intense miles woth

more intense exertions until the "' percent figure is attained. *fter "' percent is reached

successfully, without injury or overtraining, the relative amount of intense training can

cautiously and progressively be increased over a training year.

Rolul intensitati in dezvoltarea capacitatii de efoer (En)

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