ArticlePDF AvailableLiterature Review

Endurance training and performance in runners: research limitations and unanswered questions

Authors:

Abstract

The purpose of this review is to discuss several limitations common to research concerning running and, secondly, to identify selected areas where additional research appears needed. Hopefully, this review will provide guidance for future research in terms of topics, as well as design and methodology. Limitations in the research include: lack of longitudinal studies, inadequate description of training status of individuals, lack of confirmation of state of rest, nourishment and hydration, infrequent use of allometric scaling to express oxygen uptake, relative neglect of anaerobic power and physical structure as determinants of performance, neglect of the central nervous system, and reliance on laboratory data. Further research in a number of areas is needed to enhance our knowledge of running performance. This includes: body mass as a performance determinant, evaluation of methods used to measure economy of running, assessing the link between strength and running performance, and further examination of training methods. While the amount of research on distance running is voluminous, the present state of knowledge is somewhat restricted by the limitations in research design and methodology identified here.
Endurance Training and Performance
in Runners
Research Limitations and Unanswered Questions
Kris Berg
School of Health, Physical Education and Recreation, University of Nebraska at Omaha, Omaha,
Nebraska, USA
Contents
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
1. Research Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
1.1 Lack of Longitudinal Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
1.2 Inadequate Description of Training Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
1.3 Lack of Confirmation of State of Rest, Nourishment and Hydration . . . . . . . . . . . . . . . 62
1.4 Limited Use of Allometric Scaling to Express Oxygen uptake . . . . . . . . . . . . . . . . . . . 62
1.5 Relative Neglect of Anaerobic Power and Physical Structure as Determinants of
Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
1.6 Relative Neglect of the Role of the CNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
1.7 Reliance on Laboratory Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
2. Unanswered Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
2.1 Why Are Elite Runners so Small? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
2.2 How Sound is the Measurement of Running Economy Currently Used? . . . . . . . . . . . . . 65
2.3 Why is Running Economy so Variable Even in Trained Runners? . . . . . . . . . . . . . . . . . 66
2.4 How can Running Economy be Improved? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
2.5 Does Strength Training Enhance Run Performance? . . . . . . . . . . . . . . . . . . . . . . . . 68
2.6 What is the Optimal Training Stimulus for Improving Aerobic Function and
Performance? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
3. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Abstract
The purpose of this review is to discuss several limitations common to research
concerning running and, secondly, to identify selected areas where additional
research appears needed. Hopefully, this review will provide guidance for future
research in terms of topics, as well as design and methodology. Limitations in
the research include: lack of longitudinal studies, inadequate description of train-
ing status of individuals, lack of confirmation of state of rest, nourishment and
hydration, infrequent use of allometric scaling to express oxygen uptake, relative
neglect of anaerobic power and physical structure as determinants of perfor-
mance, neglect of the central nervous system, and reliance on laboratory data.
Further research in a number of areas is needed to enhance our knowledge of
running performance. This includes: body mass as a performance determinant,
evaluation of methods used to measure economy of running, assessing the link
between strength and running performance, and further examination of training
REVIEW ARTICLE
Sports Med 2003; 33 (1): 59-73
0112-1642/03/0001-0059/$30.00/0
© Adis International Limited. All rights reserved.
methods. While the amount of research on distance running is voluminous, the
present state of knowledge is somewhat restricted by the limitations in research
design and methodology identified here.
Numerous studies of distance running have fo-
cused on training, determinants of performance
and physiological profiling. Reviews of these top-
ics are available elsewhere.
[1-4]
The purpose of this
review is to discuss some of the limitations com-
mon to research on the topic and, secondly, to
identify selected areas where additional research
appears needed.
1. Research Limitations
1.1 Lack of Longitudinal Studies
The lack of longitudinal studies not only limits
our understanding of the degree to which physio-
logical changes continue to evolve over years of
training but also how and when specific changes
interact with performance improvement. Rela-
tively few longitudinal studies have been con-
ducted on runners.
[5-9]
Some physiological alter-
ations occur quickly with training, such as
increased plasma volume
[10]
and increased mito-
chondrial enzyme activity.
[11]
Maximal oxygen up-
take (V
.
O
2max
) can be significantly improved after
only 3 weeks of training, with a one-half time for
adaptation of 10.8 days.
[12]
However, other adap-
tations may not be optimised until years of training
have accrued. For example, in elite cross-country
skiers the percentage of slow twitch muscle fibre
composition before and after 8 years of training
increased 11% while training volume doubled in
that period.
[13]
The lack of longitudinal work limits under-
standing of the volume of training needed to op-
timise biological change and performance. Cos-
till
[14]
determined that improvement in V
.
O
2max
reached a limit after a training volume of ~50–60
miles/week in runners. Additional mileage up to
even 217 miles/week did not further improve
V
.
O
2max
. However, V
.
O
2max
was the only variable
used to determine the effect of increased mile-
age. It is well known that significant performance
improvement can occur without a change in
V
.
O
2max
,
[5,15,16]
so determination of how other vari-
ables respond to increased volume of training is
needed. Costill’s
[16]
study of swimmers also sug-
gests that a volume threshold of training may exist.
He observed that when collegiate swimmers re-
duced their training by half for 1 year in compari-
son to the volume in the 2 previous years that all
individuals surpassed their performance in pre-
vious years and set personal records. However, it
is unknown if the improvement was a consequence
of heavier training volume in the previous 2 years.
Absence of a control group precludes concluding
that reduced training per se was responsible for the
improvement. Wilmore and Costill
[15]
stated that
the energy expenditure in training of ~5000–6000
kcal/week in distance runners may represent an
ideal training regimen for most runners. However,
data representing Finnish cross-country skiers in-
dicate continued improvement in V
.
O
2max
with age
and increased training volume from age 15–25
years.
[13]
Training increased from ~50 km/week at
age 15 years to ~140–150 km/week at age 25 years.
In contrast, relative V
.
O
2max
remains nearly con-
stant in non-athletes after age 8–10 years.
[17]
Rel-
ative heart volume as well as V
.
O
2max
increased in
a different group of elite cross-country skiers and
was associated with increased training volume.
[18]
Elite athletes, perhaps because of their smaller
mass and superior running or skiing economy, may
be unique in their tolerance of musculoskeletal
trauma associated with high mileage training, as
well as their ability to benefit from it. Further in-
vestigation is needed in runners to determine what
physiologic variables are associated with perfor-
mance improvement over years of training and
how much improvement is actually made.
Elite runners today generally train within a
range of ~70–120 miles/week. Yet much, if not
most, of the conditioning change probably occurs
at far lower levels of training, particularly if inten-
60 Berg
Adis International Limited. All rights reserved. Sports Med 2003; 33 (1)
sity is high. Roger Bannister, the first sub 4 minute
miler, reportedly ran only 5 days weekly for an
hour performing interval training. Elite runners of
the first half of the 20th century trained minimally
by today’s standards,
[19]
but their performances
were impressive nonetheless. A point of diminish-
ing returns from increased training volume has
been suggested
[19]
and is supported by the training
habits of champion runners years ago. Astrand and
Rodahl
[20]
contend that the large training volumes
of modern endurance athletes do not promote su-
perior development of V
.
O
2max
, compared with val-
ues achieved with far less work in the 1930–1950
era. However, other determinants of performance
might be improved with high volume training and
this subject needs further study.
The high volume approach to training prevalent
today is associated with reaching elite perfor-
mance status and faster running
[21,22]
but the
performance benefit derived from this additional
volume has not been adequately assessed experi-
mentally. Lacking longitudinal data prevents iden-
tifying the specific physiologic adaptations associ-
ated with this progress. Athletes today train for
years to make performance improvements of sev-
eral percentage points. It would be interesting to
know what specific physiological adaptations are
made and the magnitude of these changes.
Short duration studies also limit the study of
training periodisation. Little published work exists
on this topic for distance running. A need exists to
first determine if periodisation elicits better perfor-
mance than a non-periodised approach. Secondly,
if periodisation is found to be effective, then the
training components that should be emphasised in
various stages of training need to be determined.
Traditionally, runners initiate training with a stage
aimed at increasing volume or miles with little em-
phasis on speed, followed by stages that emphasise
speed and improvement of V
.
O
2max
, lactate thresh-
old (LT) and running economy.
[6]
The soundness
of the sequence has not been closely examined. In
a survey study of 44 National Collegiate Athletic
Association Division I cross-country teams, vari-
ous types of training methods during specific
stages of periodisation were correlated with per-
formance at the end of the season.
[6]
Data included
different types of running as well as supplemental
forms of training such as strength work, plyometr-
ics and stretching. While only descriptive in na-
ture, such work provides at least some insight as to
the synergistic and long-term nature of training.
Conducting such research is a daunting task as par-
ticipant retention, injury, etc. are problematical in
that they limit statistical power. Having the pa-
tience to overcome such obstacles over several
seasons and years perhaps explains the relative ab-
sence of such research.
Many studies have described the acute and
chronic physiological effects of intermittent or in-
terval training (IT) or compared IT with continu-
ous training as to their effects on V
.
O
2max
, LT,
running economy, etc.
[1,23-27]
Because training
programmes combine continuous and interval
training, a comparison of one with the other pro-
vides limited information. The more important
question is how to best combine the two training
strategies over months and years of training. Little
research information on this point is available be-
cause of the prevalence of short-duration studies.
Carrying out longitudinal studies might be facili-
tated by using athletes at Olympic training centres
and national development camps.
1.2 Inadequate Description of
Training Status
Many studies fail to adequately describe the
training status of the participants. It would seem
important to know what training occurred in the
months prior to testing. For example, runners cur-
rently or recently using IT would be expected to
demonstrate limited physiological and perfor-
mance response to an IT programme in contrast to
lesser-trained athletes who have not previously
used IT. Consequently, it is important to identify
the training background of individuals to note the
potential magnitude of the training effect. Simi-
larly, the concept of periodisation is widely prac-
tised by coaches and athletes but researchers often
seem to ignore its possible impact on their data.
Endurance Training and Performance 61
Adis International Limited. All rights reserved. Sports Med 2003; 33 (1)
Thetrainingresponseshouldbeexaminedinrela-
tionship to previous training in order to distinguish
between the effects of the two. This information
can easily be described in published work and it
should aid interpretation of results.
1.3 Lack of Confirmation of State of Rest,
Nourishment and Hydration
Confirmation that testing was performed with
athletes in a rested, well-nourished and hydrated
state is omitted in most studies. Glycogen stores
[28]
and hydration
[29]
status are known to affect perfor-
mance and consequently need to be controlled in
studies, particularly when using longer perfor-
mance tests. Knowledge of these factors is well
known, yet few studies confirm that athletes actu-
ally refrained from serious training effort in the
days prior to testing. Similarly, hydration status is
rarely mentioned in the methods of studies yet it is
known to affect heart rate (HR) and blood values.
It may also affect the slow component of oxygen
uptake (V
.
O
2
). It is common to read in published
articles that individuals were encouraged to avoid
strenuous exertion the day before testing and to
avoid eating several hours beforehand, but addi-
tional information about these points is usually
omitted. Did the participants actually follow the
instructions provided? If not, was testing resched-
uled? In studies where nutritional status and hydra-
tion are particularly likely to influence test data,
measurement of urine specific gravity and the use
of a 3-day dietary recall would seem helpful. These
procedures do not involve much cost or participant
time. This information would be useful in the in-
terpretation of studies and should be described in
published work.
1.4 Limited Use of Allometric Scaling to
Express Oxygen uptake
Most research on running includes measure-
ment or discussion of V
.
O
2max
or peak oxygen up-
take (V
.
O
2peak
). The variable is typically expressed
relative to body mass (ml/kg/min) to equate ath-
letes of varying mass. However, data from the
1960s,
[20]
as well as more recently, clearly indicate
that linear scaling does not adequately adjust for
body mass. Instead of an exponent of 1.0, expo-
nents actually vary between about 0.67 and
0.75.
[30-33]
The magnitude of error in using an in-
appropriate exponent is sizeable when mass varies
considerably. For example, Astrand and Rodahl
[20]
assessed V
.
O
2max
in individuals ranging in mass
from 55–93kg. Scores were expressed as L/min,
ml/kg/min (exponent of 1) and ml/kg/min using an
exponent of 0.67. The resulting correlations be-
tween body mass and V
.
O
2max
were 0.86, –0.69 and
–0.06, respectively. Linear scaling obviously is
limited in adjusting for mass, while allometric scal-
ing using an exponent of 0.67 effectively removed
the effect of mass such that the correlation was
close to zero. The validity of the 0.67 exponent is
sound in samples where body mass, age, height and
training status are similar, but an exponent of 0.75
is suggested in more heterogeneous groups.
[32]
Nearly all research since the concept of allomet-
ric scaling was first applied to the discipline of
exercise physiology and science has used linear
scaling to express relative aerobic capacity. Even
today, nearly all published work in the field is ex-
pressed linearly. Clearly, a change in expression of
V
.
O
2
, both maximal as well as submaximal values,
needs to be made. Linear scaling makes heavier
runners appear to have lower values of V
.
O
2max
yet
higher levels of running economy since submaxi-
mal V
.
O
2
is artificially lowered. The influence of
this error on running research is problematic.
What errors are made in interpreting data not
expressed allometrically? The values for V
.
O
2max
in
runners with low body mass, which is the norm for
trained runners, are inflated. The opposite is true
for heavier runners. Elite male Kenyan runners
typically weigh ~14kg less than Caucasian run-
ners
[34]
and therefore their V
.
O
2max
scores are con-
siderably inflated using the linear standard. Inter-
estingly, the V
.
O
2max
data for elite Kenyan runners,
expressed linearly (ml/kg/min), is similar to values
for European and American runners. Conse-
quently, the performance dominance in recent
years of Kenyan runners does not appear to lie in
asuperiorV
.
O
2max
. When comparing African run-
62 Berg
Adis International Limited. All rights reserved. Sports Med 2003; 33 (1)
ners, such as Kenyans, to elite non-African run-
ners, their economy appears to be superior,
[35]
al-
though one would expect to find them less eco-
nomical with V
.
O
2
expressed linearly.
With greater frequency today, elite athletes are
tested in the laboratory and then advised to make
adjustments in training. The validity of making
such modifications is somewhat limited when ex-
pressing V
.
O
2
linearly. A lean athlete with a larger
skeletal structure and mass might be thought to
need greater emphasis in training to improve
V
.
O
2max
. In pursuit of this goal, both athlete and
coach may be frustrated by the inability to make
such a change. Increasing the intensity or volume
of training in search of an elusive goal may lead to
overtraining. Similarly, a smaller runner whose
running economy is noted to be less than expected
might be fruitlessly directed to emphasise training
to improve what appears to be a deficit. All in
all, attempts to apply laboratory data to training
are tainted because of how V
.
O
2
is expressed. Fur-
thermore, since so much laboratory data is based
on V
.
O
2
(e.g. V
.
O
2max
, velocity at V
.
O
2max
and LT,
economy), the validity of applying these data to the
training of athletes is somewhat flawed if using an
exponent of 1.
1.5 Relative Neglect of Anaerobic Power
and Physical Structure as Determinants
of Performance
The most commonly used variables in research
aimed at identifying determinants of running per-
formance have been measures of aerobic function
such as V
.
O
2max
, velocity at V
.
O
2max
(vV
.
O
2max
), LT
and running economy. While these variables are
able to predict performance and explain variance
quite well,
[36]
other factors that undoubtedly play
a role in performance are usually not addressed.
Noakes
[19]
suggested that endurance performance
may in part be determined, and even limited, by
muscle power. In recent years, measures of anaer-
obic power such as short sprints and jumps have
been shown to add considerably to the explained
variance in distance running performance.
[36-38]
In addition, physique and somatotype seem to
be worthy of continued investigation but currently
are not usually included in the battery of testing to
predict performance. Somatotype and physique of
Olympic runners are distinct from many other ath-
letic populations.
[39]
For example, distance run-
ners are leaner and more ectomorphic than many
other athletes,
[40,41]
but the importance of these
physical traits in performance has not been thor-
oughly studied. In heterogeneous samples of
runners, somatotype contributes moderately to
explained variance of running performance.
[42]
Observation of elite African runners suggests a de-
finitive prototype in which body mass is mini-
mised and facilitated by a somatotype that may be
more ectomorphic than is typical of Caucasians,
e.g. very thin legs. It would be interesting and in-
sightful to determine the variance in performance
explained by physical structure when combined
with indicators of aerobic and anaerobic power as
well.
1.6 Relative Neglect of the Role of the CNS
The model for much of the research on distance
running has assumed that the limitation to endur-
ance performance is the capacity of the heart to
pump a large volume of blood to active muscle
tissue. Consequently, the research in general has
emphasised the influence of training on the heart,
vasculature, V
.
O
2max
, LT and other indicators of the
capacity to transport and utilise oxygen. The role
of other physiologic systems, including the CNS,
has been neglected. Yet substantial evidence now
indicates that the CNS is involved in fatigue and
hence performance.
An alternative model of endurance performance
proposed by Noakes,
[43]
and supported by recent
work, suggests the importance of the CNS in un-
derstanding the physiology of training for endur-
ance performance. Kayser et al.
[44]
noted that inte-
grated electromyographic (IEMG) activity was
reduced at peak exercise while at high altitude, but
was increased with supplemental oxygen. Conse-
quently, they concluded that the CNS may be in-
volved in fatigue.
[44]
Further supporting evidence
Endurance Training and Performance 63
Adis International Limited. All rights reserved. Sports Med 2003; 33 (1)
for the role of the brain in endurance performance
is the report of significant deterioration in IEMG
over time in 100km cycling time trials.
[45]
This
change was paralleled by reduced power output
during stochastic bouts of high intensity exercise.
HR increased during the time trial supporting the
idea that the athletes did not consciously reduce
their effort. The fact that IEMG decreased ruled out
the possibility that muscle activity was reduced be-
cause of muscle glycogen depletion. Typically,
neural recruitment would be expected to increase
with glycogen depletion. The authors concluded
that the results support the existence of a central
governor that subconsciously reduces muscle re-
cruitment during prolonged exercise.
These findings support the idea that cerebral
output may be a source of fatigue and hence a de-
terminant of endurance performance. Additional
work that concurrently examines the role of multi-
ple systems appears justified. The activity of the
brain’s input and output during strenuous endur-
ance performance should be included in work ex-
amining various exercise intensities and durations,
and environmental conditions. A fuller under-
standing of fatigue may have implications for en-
durance training and performance.
1.7 Reliance on Laboratory Data
Laboratory-based testing may be limited in elic-
iting maximum performance. Foster et al.
[46]
dem-
onstrated greater physiological responses when in-
dividuals were allowed to select their own pattern
of testing rather than being assessed via a typical
incremental protocol. The former protocol leaves
the athlete in charge of determining a pace and du-
ration that is similar to actual competition. Simi-
larly, athletes tested during simulated competition
outside the laboratory exhibited higher HR than
when tested in the laboratory.
[47]
Competition elic-
its an ability to tolerate greater discomfort and for
longer periods. In training and in the laboratory,
the same level of exertion is difficult to tolerate.
Laboratory data are therefore probably something
less than the actual maximum but the extent of the
difference is not known for most variables. Perhaps
most laboratory data should be referred to as ‘peak’
values rather than maximum, which is the nomen-
clature some prefer to use in expressing the highest
level of V
.
O
2
obtained in a graded exercise test.
Current technology, using portable equipment, al-
lows the measurement of HR and V
.
O
2
while run-
ning on the track and road, which in turn increases
the probability of attaining maximal values. It also
provides knowledge of the magnitude of difference
in laboratory versus field data. Future work should
attempt to use technology that permits assessment
outside the laboratory.
2. Unanswered Questions
Several areas of research on running have not
been widely or directly studied. Also, no firm con-
clusions can be made on several topics because of
equivocal findings. These unanswered questions
appear to be fruitful areas for future work and are
highlighted here.
2.1 Why Are Elite Runners so Small?
Observation of non-elite runners at most road
races in the US suggests that body mass is a deter-
minant of running performance. Even at this level
the winners and top finishers are usually rather
small people. At the elite level the difference is
striking. In a study of elite South African runners,
African athletes were 168cm in height and
weighed 61kg while elite Caucasian runners were
180cm and 70kg.
[34]
Do smaller stature and mass
provide an advantage? And if so, what are the
mechanisms involved? Surprisingly little research
has addressed this question.
Several factors may explain the advantage of
low body mass in running. Ground reaction forces
while running are reduced in lighter runners than
heavier ones. Attenuating shock may be a requisite
to maintaining the high mileage/high intensity
characteristic of today’s elite runners and athletes
of limited mass; this may be why they have an ad-
vantage. Elite African runners reportedly run a
much larger percentage of their mileage doing
quality work than their western counterparts.
[34]
Coaches often prescribe intense or quality running
64 Berg
Adis International Limited. All rights reserved. Sports Med 2003; 33 (1)
as a percentage of the athlete’s weekly mileage.
For example, Daniels
[48]
recommended that speed
training comprise ~5% of weekly mileage, training
to improve V
.
O
2max
~10% and training to elevate
LT ~12%. The rationale for such recommenda-
tions is based on injury avoidance, as well as over-
training. It would be interesting to compare the rate
of athletic injury and overtraining in African run-
ners and Western runners. The more physically de-
manding lifestyle, beginning in childhood, that in-
cludes large amounts of walking and running over
rugged terrain
[49]
may provide a foundation of con-
ditioning that allows them to withstand greater de-
mands when structured training ensues. Reduced
ground reaction forces while running may also be
involved.
Another possible advantage related to the lim-
ited mass of the elite runner is heat accumulation;
this is largely the function of heat production ver-
sus heat dissipation. Heavier runners produce and
store more heat at a given submaximal running ve-
locity.
[50,51]
Furthermore, in a recent report, the
correlation between heat storage and body mass
was increased at higher environmental tempera-
tures. Also, immediately following a 30 minute
submaximal run, the decrement in 8km race pace
was significantly and negatively related to body
mass (r = –0.77, p <0.0004).
[51]
The apparent ther-
modynamic advantage of lighter runners may al-
low them to run more intensely or longer before
reaching a limiting core temperature. A core tem-
perature of 39.5°C has been posited as a threshold
for fatigue. This threshold temperature appears to
be the same for runners of various fitness levels.
Fitter or more gifted runners can simply run longer
or faster before reaching this temperature.
[52]
As
temperature rises while running, metabolism is
prompted upwards which is reflected by a rise in
V
.
O
2
and HR. Heavier runners generate more heat,
and therefore a greater oxygen cost of maintaining
a given pace, and would reach the critical 39.5°C
temperature sooner. Runners with very small
mass, such as the Kenyans, would be less heat-
challenged. This would be advantageous in com-
petition, but may also allow training loads to be
increased in volume and intensity, and especially
volume at high intensity.
Recent work indicates that altered cerebral
function, rather than muscular factors, may be as-
sociated with fatigue during prolonged work in the
heat.
[53-55]
In well-trained cyclists, electroenceph-
alogram activity over the prefrontal cortex, which
is involved in the initiation of voluntary move-
ments, decreased as core temperature rose. Con-
current electromyographic activity over time indi-
cated no impairment of neuromotor recruitment
and discharge rates.
[55]
Consequently, evidence
exists that fatigue associated with hyperthermia
may be due to reduced cerebral activity rather than
peripheral factors. Further work is justified to ex-
amine the role of the brain as a factor in the limi-
tation to exercise.
Why is heat production and storage higher in
larger runners? The answer may lie in the allomet-
ric relationships of heat production and dissipation
to body mass. Heat production would seemingly
increase with mass, which is a 3-dimensional con-
cept since height, width and depth are all involved.
Heat dissipation, however, appears to be related to
body surface area, which is 2-dimensional. Thus,
increased mass during work would theoretically
increase heat production exponentially placing
larger individuals at a disadvantage in sustaining
high-intensity exercise. Further clarification re-
garding these points is needed to better understand
the limits possibly imposed by mass.
2.2 How Sound is the Measurement of
Running Economy Currently Used?
Running economy affects running speed in
competition and so is an important determinant
of performance.
[36]
It is usually measured in the
laboratory as the relative oxygen cost (ml/kg/min)
to run at a given submaximal velocity. However,
usingoxygencosttoassesseconomymaynotbe
entirely sound. First, actual mechanical work
performed is unaccounted for, which in part in-
validates the procedure. Also, substrate utilisa-
tion is not factored into the calculation of the en-
ergy cost of running. It has been suggested that
Endurance Training and Performance 65
Adis International Limited. All rights reserved. Sports Med 2003; 33 (1)
fitter runners with high maximum oxygen uptakes
mightbeabletometaboliselargeramountsoffat
simply because of possessing a greater reserve of
oxygen transport and utilisation. Several investiga-
tions reported a negative correlation between
V
.
O
2max
and economy in trained runners.
[56,57]
It
seems unlikely that fitter or more genetically gifted
runners would tend to be more wasteful of their
oxygen uptake than others. A higher, rather than
lower, submaximal V
.
O
2
may be beneficial in long
duration events such as the marathon if it is asso-
ciated with a greater utilisation of fat as a substrate,
which would spare the limited muscle and liver
glycogen stores. Consequently, measurement of
economy as presently done is problematical and
needs to be re-examined. Perhaps measurement of
work could be accomplished more accurately than
in previous years through the use of accelerometers
and force plates which are more readily available
to researchers today. Collaboration of biomech-
anists and exercise physiologists would be fitting.
The problem of substrate utilisation as a con-
founder also needs to be dealt with. Perhaps the
oxygen cost could be corrected for substrate
utilisation by expressing economy as kcal of en-
ergy expenditure rather than oxygen. Thus, the
economy of runners might be compared in units of
kcal per joule of work performed or kcal per unit
of velocity. An equation estimating the mechanical
power of running has been developed and includes
respiratory exchange ratio (RER) in the calcula-
tion.
[58]
Another alternative when making statisti-
cal comparisons of economy among groups would
be to make an adjustment using analysis of covar-
iance using RER as a covariate.
2.3 Why is Running Economy so Variable
Even in Trained Runners?
Running economy appears to be multifactorial,
with possible determinants including skill or
biomechanics, training velocity, muscle fibre type,
V
.
O
2max
, substrate utilisation, muscle power and
flexibility. This complexity may explain its wide
variability even in trained runners.
[5,59]
For exam-
ple, Svendenhag and Sjodin
[60]
found that econ-
omy varied by as much as 30% in trained runners.
If economy was largely a matter of motor learning,
then the relatively simple skill of running would
seemingly be mastered by more runners, which
would reduce the variability of economy. Some
work has examined the biomechanics of running
but the conclusions are not supportive of biomech-
anics being a primarydeterminant of running econ-
omy. Runners are often advised to shorten their
strides to improve economy,
[19]
yet some research
indicates that chronic training increases stride
length and reduces stride rate.
[8]
Biomechanical
variables such as arm carriage, vertical oscillation
of the centre of gravity, stride rate and length, Q
angle and kinetics of the thigh, foot and ankle
would be logical candidates for study. Anecdot-
ally, great runners seem to be noted for their min-
imum vertical oscillation.
[19]
In a study of runners
matched for V
.
O
2max
, it was reported that the verti-
cal force in slower runners was about twice that of
faster runners.
[61]
Our knowledge of the influence
of biomechanics on economy today is limited and
a collaborative effort between the biomechanist
and exercise physiologist is needed.
Running economy appears to be speed-specific,
so that a marathoner tends to be more economical
at marathon pace than 800 and 1500m specialists,
while the opposite is true at middle distance
pace.
[31]
Thus, comparison of economy in runners
must consider the distance and velocity specific-
ally trained for. Comparing marathoners and mil-
ers at a submaximal speed below LT favours the
marathoners. Another means of demonstrating en-
hanced running economy with training is improved
vV
.
O
2max
with little or no change in V
.
O
2max
.Jones
and Carter,
[2]
in a recent review, reported several
studies documenting such improvement in elite as
well as untrained runners. These works suggest
that the most meaningful measurement of running
economy should occur near or at race pace rather
than some arbitrary submaximal velocity, which
is commonly done. For marathoners, submaximal
velocity similar to race pace would seemingly
be most appropriate while velocities as high as
66 Berg
Adis International Limited. All rights reserved. Sports Med 2003; 33 (1)
vV
.
O
2max
would be more pertinent for 1500, 5000
and 10 000m specialists.
Another determinant of economy may be mus-
cle fibre type. Athletes with an abundance of type
I fibres appear to produce less lactate with an as-
sociated lower oxygen cost.
[62]
Lack of flexibility
is also associated with better running econ-
omy.
[63,64]
The suggested mechanism is greater
storage and utilisation of elastic energy during
the stretch-shortening cycle while running. The
greater contribution of elastic energy in theory
would reduce the oxygen cost of running. It has
also been suggested that tightness of the hips
and trunk may aid in stabilising the pelvis and spi-
nal column, thus requiring reduced muscle con-
traction and energy expenditure.
[63]
However, any
conclusion regarding the flexibility-economy
relationship should be viewed with caution as no
experimental studies have been conducted to
demonstrate a cause-effect relationship. As run-
ners log more mileage they may become more skil-
ful, convert more type II fibres to type I and also
lose flexibility. The integrated role of each factor
in affecting economy is unknown.
The superiority of the African runner in part
seems to be explained by economy.
[35]
Trained, but
not elite, African and Caucasian runners were
compared while running at current 10km race
pace. The two groups were matched for body mass
and 10km performance. The African runners were
5% more economical, ran at a higher percentage of
V
.
O
2max
(92 vs 86%), yet their lactate level was
only slightly higher (5.2 vs 4.2 mmol/L; p >0.05).
Mechanisms explaining these differences are un-
known but superior lactate removal and mitochon-
drial enzyme capacity were suggested.
2.4 How can Running Economy
be Improved?
Training improves economy through several
mechanisms. Some studies have indicated that
economy improves with increased mileage and
age.
[57,65,66]
High-intensity training has also been
reported to be effective in eliciting improved econ-
omy.
[65,67]
Improved economy has been demon-
strated in several short-term studies.
[67,68]
Running
in and of itself may improve economy by reducing
the cost of breathing,
[67]
converting type II fibres
to type I fibres and tightening muscles of the
hips, which may facilitate using more elastic en-
ergy in these muscle groups.
[63]
Plyometric train-
ing, sprinting and explosive weight training have
also been shown to improve economy.
[37]
Conse-
quently, the means of improving economy appear
to be as diverse as the number of factors affecting
it.
Researchers interested in studying economy
should ensure that athletes are well rested when
tested. Some of the energy generated while run-
ning is derived from the elastic component in
muscle, tendon and fascia, particularly at higher
velocities.
[69]
Muscle fatigue and soreness are ac-
companied by damage to contractile proteins, as
well as these soft tissues. Hence, if an athlete is
tested for running economy the day after strenuous
exertion, then additional motor units and muscle
fibreswouldprobablyberecruitedduringtherun-
ning test and elevate V
.
O
2
. Shoe weight should be
noted in studies assessing economy, as small dif-
ferences in weight alter the energy cost measur-
ably.
[70]
In studies assessing changes in running
economy shoe type and weight should be stand-
ardised. Often in the literature little or nothing is
stated regarding whether or not any steps were
taken to assure that all tests were conducted in a
rested state. Such information should be the norm
in published work on the subject.
In summary, measurement of running economy
by measuring submaximal V
.
O
2
was adopted and
used because of its simplicity in data collection and
interpretation. However, research is needed to
quantify the work actually done while running in
order to better understand economy. Also, much of
the work on running economy was carried out be-
fore recognition of the slow component of V
.
O
2
.
Hence, values reported in the literature on the ox-
ygen cost of running may reflect the contribution
of the slow component in varying degrees, depend-
ing on the intensity and duration of the running
speed used. Future work should consider the slow
Endurance Training and Performance 67
Adis International Limited. All rights reserved. Sports Med 2003; 33 (1)
component of V
.
O
2
in the design and measurement
of oxygen cost. Lastly, more work is needed where
the design includes assessment of multiple vari-
ables such as fibre type, biomechanics, training
variables, physical structure, flexibility, etc., such
as the study by Pate et al.
[57]
This type of compre-
hensive analysis will be useful in determining how
much variance is explained by specific variables.
2.5 Does Strength Training Enhance
Run Performance?
Strength training seems to be under-utilised in
the training of runners compared with other endur-
ance athletes such as swimmers, cyclists and cross-
country skiers. Many elite runners attained this sta-
tus without ever resorting to strength training. The
disparity in the use of weight training in runners
may stem from the complexity of running as a neu-
romotor task. Cycling isolates the great majority of
the work to the muscles of the hip and thigh. In
contrast, running requires more dynamic upper
body involvement and trunk rotation, in addition
to recruitment of the primary movers in the hip,
thigh and calf. The relative simplicity of cycling
may facilitate designing and finding weight train-
ing exercises that mimic the lower extremity mo-
tions of cycling. Most weight training exercises for
the lower extremities, particularly those using ma-
chine weights, may limit mimicking the movement
of running. Traditional exercises, such as knee ex-
tension and knee flexion, are open kinetic chain
motions that are dissimilar to running mechanics.
Even closed chain kinetic exercises, such as the
squat and power clean, may be limited in specific-
ity as they are performed with both feet on the
ground rather than one foot as in running. Tradi-
tional weight exercises are also performed slowly
in contrast to the relatively high velocity of dis-
tance running. Thus, traditional weight training ex-
ercises appear to offer limited likelihood of perfor-
mance enhancement. Exceptions may occur in
individuals with limited basic strength, such as se-
niors and youth.
Resistance training for swimmers emphasises
specificity of training. Exercise equipment, such as
a swim bench, were developed to facilitate build-
ing strength in the prone position while mimicking
the mechanics of various strokes. Pulleys with
weights have been used for years by swimmers and
allow mimicking of swim strokes. In cycling,
[71]
swimming
[72]
and cross-country skiing
[73]
research
indicates that strength training enhances perfor-
mance. In cross-country skiing the importance of
upper body and torso power is demonstrated by the
observation that elite skiers are more powerful in
the upper body than non-elite skiers. Recommen-
dations from this research indicate that in cross-
country skiing more emphasis should be given to
upper body strength/power training.
[73]
The lack of
supporting evidence for strength training in run-
ning is in striking contrast to that for the previously
mentioned sports. However, it seems unlikely that
running would be unique in not being facilitated by
strength and power enhancement. The reason may
lie in the complexity of the motor pattern as dis-
cussed previously. Perhaps performance enhance-
ment in running only awaits the development of
training exercises that truly are specific to running.
Research is clearly warranted here.
A widely cited source demonstrating that
strength training might aid running performance
observed that while weight training did not alter
V
.
O
2max
, it did allow a longer duration of effort at
V
.
O
2max
.
[71]
This specific improvement would
seemingly have application to middle distance
events such as the 800 and 1500m events. How-
ever, individuals in the study were untrained,
which may limit application to the trained runner.
Other studies indicate that sprint time and peak
torque at high velocity (400 degrees/sec)
[38]
and
anaerobic power
[36]
explain a good portion of the
variance in distance running performance in
trained runners, although not as well as measures
of aerobic power such as velocity at LT (vLT)/ve-
locity at ventilatory threshold and vV
.
O
2max
.
Recent investigations have demonstrated that
plyometric jump performance is a meaningful pre-
dictor of distance run performance,
[74]
and that
plyometric training improves distance run perfor-
mance.
[37,75]
Performance in 5000m run time im-
68 Berg
Adis International Limited. All rights reserved. Sports Med 2003; 33 (1)
proved by ~30sec in experienced well-trained run-
ners, although training volume was reduced.
[37]
Stride length and V
.
O
2max
remained unchanged, but
foot contact time on a force plate decreased 7%.
The advantage of this type of training for running
is that it allows training movements that are very
similar to running. Running is, by definition, a se-
ries of hops, so logically, hopping and skipping
activities closely resemble running. Furthermore,
the velocity of movement is similar to running. By
increasing the rate of force development, stride
rate or length might be improved. A small im-
provement in either variable across the many steps
taken while racing might result in improved run-
ning. Consequently, it seems logical that plyomet-
ric training, incorporating movements similar to
running, offers good potential for resistance work
to aid run performance.
The volume and intensity of weight training
probably needs to be limited so that the develop-
ment of muscle mass is minimised. Yet, some ad-
ditional muscle mass may not be detrimental as
long as it contributes to improved power and shock
absorption.
Sprinting, striding, short runs up hills or steps
and plyometrics are likely useful training adjuncts
to enhance performance because of the similarity
in velocity and movement pattern to distance run-
ning. The fact that these methods have been tradi-
tionally used provides further support that they
seem to contribute something unique. These tech-
niques may improve or at least maintain muscle
power, which is usually reduced as a consequence
of endurance training.
[76]
Furthermore, they do so
without apparent gain of muscle mass. Conse-
quently, application of typical strength training
programmes in runners who previously or concur-
rently use these techniques may not provide
enough specific strength and power development
above that attained as a result of speed work, hills
and plyometrics. More research is needed in this
area.
2.6 What is the Optimal Training Stimulus
for Improving Aerobic Function
and Performance?
Training intensity used for athletes usually falls
in the range of ~70–100% V
.
O
2max
.
[1,77]
Obviously,
the volume of work is greater when intensity is in
the lower portion of this range. Because both in-
tensity and volume are stimuli for improving aer-
obic fitness and performance, researchers for years
have been curious as to what combination of the
two variables might be optimal. The two variables
are inversely related so that maximising one is
done at the expense of the other. Noakes
[19]
con-
cluded that an important benefit of higher mileage
training is to improve economy which permits run-
ning at a faster velocity. However, fraction utilisa-
tion is not improved.
[21]
Some suggest that training at LT is an optimal
compromise as it allows a good combination of
volume and intensity.
[78,79]
Also because vLT is
well correlated with performance, it appears to be
a particularly beneficial training intensity.
[38]
Oth-
ers believe that the slowest running velocity that
elicits V
.
O
2max
may be the optimal training stimu-
lus.
[80]
However, it remains unresolved whether it
is better to exercise at a high but submaximal frac-
tion of V
.
O
2max
for a longer period or to exert at
V
.
O
2max
but for a shorter duration. In evaluating
research on the topic it should be noted that phys-
iological effects may not coincide with improved
performance. For example, performance is known
to change fairly dramatically even when no alter-
ation of V
.
O
2max
occurs.
[5,69]
Scandinavian researchers compared various
work intensities and work-rest ratios for their ef-
fect on V
.
O
2
and blood lactate concentration
(BLC).
[20]
Essentially, as long as the work bout
was the same length or longer than the recovery
period, then V
.
O
2max
could be reached and main-
tained for a longer duration than possible during
continuous exercise at a work rate or velocity that
elicited V
.
O
2max
. Duration and spacing of the work
and rest periods were crucial in determining the
associated V
.
O
2
. For example, alternating 10 sec-
ond work intervals with 5 second rest periods al-
Endurance Training and Performance 69
Adis International Limited. All rights reserved. Sports Med 2003; 33 (1)
lowed the highest V
.
O
2
to be reached. Increasing
the rest to 10 seconds dramatically reduced the
V
.
O
2
. In addition, V
.
O
2
remained high during the
brief rest periods.
[24]
Surprisingly, blood lactate
level was kept much lower than when work was
continuous. It was believed that the muscle phos-
phagens supplied much of the substrate during in-
termittent work and that myoglobin supplied addi-
tional oxygen, which reduced the load on the
glycolytic pathways resulting in lower lactate lev-
els. Thus, a greater duration of time spent at
V
.
O
2max
was allowed. Longer work bouts, such as
30 and 60 seconds alternated with rest periods of
equal length, failed to elicit equivalent V
.
O
2
values
yet BLC was quite high.
[24]
A large number of stud-
ies (reviewed in Billat
[1]
) conducted since this pe-
riod support the value of IT in improving various
parameters of aerobic fitness as well as perfor-
mance. However, this research only substantiates
that some IT is needed to optimise performance. It
does not address the question as to how much is
needed and how it should best be blended into the
typical training regimen. Only longitudinal work
will permit an answer to this question.
Recent work has shed new light on the topic,
which may be useful in solving the problem of di-
minished training volume when intensity is raised.
DeMarie et al.
[81]
studied V
.
O
2
kinetics in middle-
aged runners. They noted that running at a pace
midway between LT and vV
.
O
2max
(v50% delta)
slowly raised the V
.
O
2
during the run until it
equalled and then surpassed V
.
O
2max
, as measured
in an incremental test to exhaustion. Individuals
performed interval training with a work-rest ratio
of 2
:
1. Duration of the work bouts and recovery
jogs individualised for each participant lasted be-
tween 4–6.5 minutes and 2–3.25 minutes for the
work and rest periods, respectively. The mean V
.
O
2
actually reached during an intermittent run at
v50% delta was 64 ml/kg/min, while the mean
peak value achieved in the incremental test was 56
ml/kg/min. V
.
O
2max
peaked at 61 ml/kg/min during
continuous running at v50% delta. BLC after run-
ning at v50% delta intermittently and continuously
were 6.5 and 7.8 mmol/L, respectively. Total du-
ration of time at or above V
.
O
2max
, as measured in
the incremental test, was extended from ~5 min-
utes during continuous running to ~10.5 minutes in
the IT format. The V
.
O
2
slow component explained
the slow rise in V
.
O
2
that eventually reached supra-
maximum values. The results of this study are pro-
vocative in addressing the problem of how to
achieve volume and intensity. The fact that
V
.
O
2max
, attained in a graded test, was not only
achieved but was sustained longer, and at a lower
BLC, theoretically makes this type of training
uniquely valuable. The fact that it can be achieved
while running at a pace slower than vV
.
O
2max
sug-
gests less ground reaction force and with it less
likelihood of acute, as well as chronic, injury. The
reduced lactate level may indicate a lesser degree
of physiologic stress that, if accompanied by lower
ratings of perceived exertion, may be important in
terms of reducing the occurrence of overtraining.
On the other hand, the physiologic benefits of
slower running may be limited as the main goal of
all training should be increased race pace. Further
work relating this training to success in competi-
tion is needed. It would also be useful for future
studies on this topic to examine training-related
factors such as ratings of perceived exertion, mark-
ers of stress (e.g. catecholamines, cortisol) and
overtraining (e.g. Profile of Mood States, hor-
mones and HR variability) and injury rate. These
factors seem to mark the upper limits of training
and it would be useful to compare how various
training regimens challenge these limits.
It is still unresolved whether or not a better per-
formance results from training at v50% delta com-
pared with the actual vV
.
O
2max
attained in a short
incremental test. Does the lower velocity limit
improvement of economy at higher running veloc-
ities, such as 1500 and 5000m, which are run at
paces above or very close to vV
.
O
2max
?Theslowest
pace to achieve V
.
O
2max
may be beneficial in some
aspects of training, such as mitochondrial mass and
enzymes and perhaps would be more valuable to
longer events, while use of the highest speed at
V
.
O
2max
may be more beneficial at shorter distances
where race pace occurs at or above vV
.
O
2max
.Also,
70 Berg
Adis International Limited. All rights reserved. Sports Med 2003; 33 (1)
development of anaerobic capacity and tolerance
to pH would probably be better enhanced with
training at the higher speed. Consequently, while
several new concepts dealing with IT have been
tested, further work is needed to identify whether
or not the various types of training to elicit V
.
O
2max
have specific applications to various race dis-
tances. To the author’s knowledge, no work has
been done testing this hypothesis.
Intermittent training also has implications for
assessing V
.
O
2max
in athletes. Peak values for V
.
O
2
in the DeMarie et al.
[81]
study were lowest during
an incremental test, intermediate during a contin-
uous run at v50% delta and highest in the intermit-
tent exercise session. Because the differences in
these values were statistically significant, but also
meaningful, laboratory test protocols might use an
intermittent approach at v50% delta in order to
capture the effect of the V
.
O
2
slow component.
V
.
O
2peak
was 12% higher in the intermittent exer-
cise than the incremental test. This value exceeds
the seasonal variation in trained runners. This is a
topic that requires further investigation as it is
questionable whether or not V
.
O
2max
is actually
achieved in some test protocols.
To effectively answer the question regarding
optimum training intensity, more longitudinal
work will be needed. What appears to work best in
the short-term may not be optimal over the long-
term. Training is a complex process that must be
studied over years, not just weeks and months. The
interactions among intensity, duration and fre-
quency are considerable, and the number of per-
mutations possible for study is nearly endless.
Detailed examination of periodisation will be re-
quired in answering this question.
The dominance of African runners in the last 2
decades may provide valuable insight into the
training process. Their training appears to be rela-
tively uncomplicated. In essence, intensity is
emphasised over volume. African runners train at
vigourous paces on a nearly daily basis and much
of their running is done on hills. The frequency of
the high intensity work results in a much higher
percentage of their running mileage being at or
above LT pace.
[82]
In contrast, in the author’s opin-
ion, training in western countries appears to be
guided by a ‘more is better’ philosophy which ne-
cessitates limiting intensity. Furthermore, while
elite athletes in most western countries can be
physiologically assessed in the laboratory and
training programmes modified accordingly, the
success of such efforts is unknown. In interna-
tional competition, however, African runners not
having these advantages continue to predominate.
One cannot help but wonder if some of the limita-
tions inherent in scientific methodology (e.g. lin-
ear versus allometric scaling, reliance on labora-
tory data) also limit the quality of the feedback
provided to athlete and coach. The fact that Afri-
can runners 50 years ago were not competitive at
world class levels and that they continue making
progress in terms of setting new records suggests
that genetic endowment is not the only cause for
their success. In recent years, performance by
American runners has declined, rather than im-
proved, in spite of being exposed to more informa-
tion about training, nutrition and hydration, etc.
More extensive scientific examination of the train-
ing philosophy and techniques of African runners
is needed, as well as testing these techniques in
western runners.
3. Conclusion
Much knowledge has accumulated in recent de-
cades about distance running performance and
training. However, current research methodology
is characterised by a number of flaws and assump-
tions that limit progress in our understanding. Fur-
ther development and insight into distance running
will require addressing, at minimum, the following
methodological issues: more longitudinal work is
needed, training status of participants should be
described in detail, the state of rest, nourishment
andhydrationshouldbeassessedandreported,al-
lometric scaling should be used more frequently to
express V
.
O
2
particularly when body mass is vari-
able, anaerobic power and physical structure
should be incorporated in studies aimed at predict-
ing or explaining variance in performance, the role
Endurance Training and Performance 71
Adis International Limited. All rights reserved. Sports Med 2003; 33 (1)
of the brain as a central governor needs to be fur-
ther assessed in a variety of exercise intensities and
environments and more data are needed in compet-
itive and field conditions rather than relying on lab-
oratory testing.
Acknowledgements
Appreciation is extended to Dr Richard Latin and Mr
Robert Buresh of the University of Nebraska at Omaha, and
Dr Jerry Mayhew of Truman State University for reviewing
the manuscript and providing helpful comments. The authors
have provided no information on sources of funding or on
conflicts of interest directly relevant to the content of this
review.
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Endurance Training and Performance 73
Adis International Limited. All rights reserved. Sports Med 2003; 33 (1)
... De manière identique à la taille, alors que la distance décroit progressivement du marathon au 100m, Un autre facteur pouvant expliquer l'avantage d'un faible poids de corps sur les longues distances est la force de réaction du sol qui est réduite pour les coureurs les plus maigres par rapport aux plus lourds (315). Dans la droite ligne de ces idées, afin de maintenir un kilométrage et une intensité élevés durant l'entraînement, les athlètes de masse moindre ont un avantage par une diminution de la somme des forces résultantes de la réaction du sol (315). ...
... De manière identique à la taille, alors que la distance décroit progressivement du marathon au 100m, Un autre facteur pouvant expliquer l'avantage d'un faible poids de corps sur les longues distances est la force de réaction du sol qui est réduite pour les coureurs les plus maigres par rapport aux plus lourds (315). Dans la droite ligne de ces idées, afin de maintenir un kilométrage et une intensité élevés durant l'entraînement, les athlètes de masse moindre ont un avantage par une diminution de la somme des forces résultantes de la réaction du sol (315). Pugh (447) supporte l'idée selon laquelle les plus gros gabarits sont plus exposés à la résistance de l'air durant la course et par conséquent les coureurs petit et maigres seraient bénéficiaires. ...
... A ceci s'ajoute que la masse corporelle augmente les contraintes thermiques, les coureurs plus lourds atteignent une limite de stockage de chaleur plus rapidement que les plus maigres (448). L'avantage apparent de la thermodynamique des coureurs légers leur permet de courir plus intensément ou plus longtemps avant d'atteindre une température centrale limite (315,448,449). De plus, cet avantage s'exprime non seulement en compétition mais aussi lors des entraînements afin de supporter des charges, intensités supérieures (315). ...
Thesis
The purpose of this thesis is to study the morphological changes of top athletes and identify structural links between performance and anthropometric characteristics. This thesis is comprised of various studies that analyze the highest level of performance by morphological aspect and different levels of proof. At first, we show differentiated changes between high level athletes and individuals in the general population (Studies 1 and 2), presupposing that athletes draw benefits from their anthropometric characteristics. Then we highlight the direct links between anthropometric characteristics and performance in track and field athletes and rugby players (studies 2 and 5): rugby teams with heavier forwards and taller backs are more successful than others. In track and field, calculated allometric coefficients show the impact of mass depending on the distance of the race and sex, suggesting a possible anthropometric progression margin for female athletes. The third level of supporting evidence, highlights the existence of couples [optimal morphologies - optimal performance], biometric attractors beneficial in scoring in basketball (Study 3), and BMI optimum with performance intervals in race distance (studies 4, 5 and 6). Mass, height and BMI are relevant indicators used to specify athletes between different events (morphological gradients in track and field following the spectrum of distances, like energy gradients) but also according to their level (inverse gradient between mass and height according to middle and long distances and sprints). These three indicators also reveal morphological differentiation depending on the specific position. Comparing the two, changes in mass and height show asynchronous growth indicative of atypicity. Independent from BMI’s primary function of measuring body size and obesity, it should be refined as a useful indicator of high level performance. Indeed, it reveals trade-offs between power, energy capacity and organization of efficient body structure for high level athletes. In athletic performance, the whole body is in action, and mass, height and BMI take into account the entire athlete who moves. The findings of this thesis will assist in making conclusions and new ways to understand performance and will assist to generate the development of experimental protocols. Physiques are the expression of the performance as well as the organization from which it is realized. The results of this thesis, based on the analysis of consistent databases, provide a new vision on morphological optimizations. For the purpose of performance, it is necessary to know the optimizations established in order to situate athletes in their morphological fields, but also enable them to move towards better anthropometric adaptation specific to their activities.
... Analysis: Table 3 presents 13 studies from 1983 to 2014 [13,23,[26][27][28][33][34][35][36][37][38][39][40][41][42][43][44][45][46]. Physiological variables such as VO2max [23,[32][33][34]38] and vVO2max continue to be prominent [27,28,33]. ...
... Physiological variables such as VO2max [23,[32][33][34]38] and vVO2max continue to be prominent [27,28,33]. Of the 13 studies, seven have a prediction equation [7,23,26,28,34,37,44]. The coefficients of determination (R 2 ) of the equations by Bale et al. (1986) are moderately high (from 0.75 to 0.86) and are based on training variables including the number of training sessions, miles run, years of training and a somatotype component such as ectomorphy [7,38] and the studies by Fay et al. (1989) with R 2 >0.84, based on the velocity associated with metabolic variables such as lactate at 2 and 4 mmol/L and at VO2max (Table 3). ...
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Full-text available
Physiological variables such as maximal oxygen uptake (VO2max), velocity at maximal oxygen uptake (vVO2max), running economy (RE) and changes in lactate levels are considered the main factors determining performance in long-distance races. The aim of this review was to present the mathematical models available in the literature to estimate performance in the 5000 m, 10,000 m, half-marathon and marathon events. Eighty-eight articles were identified, selections were made based on the inclusion criteria and the full text of the articles were obtained. The articles were reviewed and categorized according to demographic, anthropometric, exercise physiology and field test variables were also included by athletic specialty. A total of 58 studies were included, from 1983 to the present, distributed in the following categories: 12 in the 5000 m, 13 in the 10,000 m, 12 in the half-marathon and 21 in the marathon. A total of 136 independent variables associated with performance in long-distance races were considered, 43.4% of which pertained to variables derived from the evaluation of aerobic metabolism, 26.5% to variables associated with training load and 20.6% to anthropometric variables, body composition and somatotype components. The most closely associated variables in the prediction models for the half and full marathon specialties were the variables obtained from the laboratory tests (VO2max, vVO2max), training variables (training pace, training load) and anthropometric variables (fat mass, skinfolds). A large gap exists in predicting time in long-distance races, based on field tests. Physiological effort assessments are almost exclusive to shorter specialties (5000 m and 10,000 m). The predictor variables of the half-marathon are mainly anthropometric, but with moderate coefficients of determination. The variables of note in the marathon category are fundamentally those associated with training and those derived from physiological evaluation and anthropometric parameters.
... M any physiological variables are associated with aerobic function and are used to determine running performance [9]. These are: maximal oxygen uptake ...
... Segundo Coetzer et al. [18], os corredores africanos de elite treinam mais quilómetros a intensidades elevadas que os seus concorrentes caucasianos. A menor massa corporal que os caracteriza pode estar diretamente correlacionada com uma menor incidência de traumas e lesões musculoesqueléticas [19] que lhes permite a manutenção, época após época, desse tipo de treino em qualidade. ...
Article
Full-text available
O êxito competitivo dos corredores de meio-fundo e fundo provenientes do Leste de África tem sido motivo de muita especulação. Várias razões têm sido aduzidas para justificar a excelência competitiva desses atletas, entre as quais se salientam um especial traço genético favorável ao rendimento desportivo nas corridas de duração e as condições ambientais específicas que potenciam esses atletas desde o seu nascimento. Seleção genética versus determinismo do envolvimento tem sido o tema recorrente para diversos estudos que procuram a razão fundamental para o êxito desportivo dos corredores africanos de elite. Este estudo pretendeu fazer uma revisão atualizada dos vários contributos que nos permitam fazer alguma luz sobre os fatores eventualmente discriminadores entre os corredores de meio-fundo e fundo africanos e caucasianos. Tentamos abordar o êxito desportivo dos corredores Leste Africanos através de dois tipos de enfoque: biológico (genético, antropométrico, fisiológico, morfológico) e sócio ambiental (características do envolvimento, perfil do treino e recuperação, nutrição, estilo de vida, perfil psicológico e emocional). Da análise dos vários estudos verificamos que a genética não discrimina os corredores de meio-fundo e fundo africanos dos seus pares caucasianos. Também os indicadores fisiológicos apresentam reduzida capacidade discriminativa. Parece existirem traços antropométricos característicos dos corredores negros – menor perímetro e maior comprimento da perna – que podem corresponder a vantagens biomecânicas para a corrida, mas que não suficientes, por si só, para justificar a excelência competitiva dos corredores africanos de elite. Das condicionantes ambientais e sociais, verifica-se que as características do envolvimento (altitude, temperatura), a alimentação e o estilo de vida não são a razão das diferenças verificadas no perfil competitivo dos corredores negros e brancos. Diferenças no perfil de treino e recuperação bem como as características psicológicas e emocionais dos corredores Africanos, parecem poder justificar o domínio dos corredores negros Africanos de meio-fundo e fundo nas principais competições desportivas internacionais.Palavras-chave: corrida, genética, altitude, fisiologia, antropometria, rendimento.
... Sometimes, depending on the scope of the study, some anaerobic metrics are provided, appreciating sport science currently has limited validity in accurately and sensitively measuring the anaerobic domain ( Haugen et al., 2018). Furthermore, middle-distance coaching education is predominated by aerobic based energy system teaching (Berg, 2003;Thompson, 2016;Sandford, 2018), which may skew the over-emphasis on these performance elements. ...
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Middle-distance running provides unique complexity where very different physiological and structural/mechanical profiles may achieve similar elite performances. Training and improving the key determinants of performance and applying interventions to athletes within the middle-distance event group are probably much more divergent than many practitioners and researchers appreciate. The addition of maximal sprint speed and other anaerobic and biomechanical based parameters, alongside more commonly captured aerobic characteristics, shows promise to enhance our understanding and analysis within the complexities of middle-distance sport science. For coaches, athlete diversity presents daily training programming challenges in order to best individualize a given stimulus according to the athletes profile and avoid “non-responder” outcomes. It is from this decision making part of the coaching process, that we target this mini-review. First we ask researchers to “question their categories” concerning middle-distance event groupings. Historically broad classifications have been used [from 800 m (~1.5 min) all the way to 5,000 m (~13–15 min)]. Here within we show compelling rationale from physiological and event demand perspectives for narrowing middle-distance to 800 and 1,500 m alone (1.5–5 min duration), considering the diversity of bioenergetics and mechanical constraints within these events. Additionally, we provide elite athlete data showing the large diversity of 800 and 1,500 m athlete profiles, a critical element that is often overlooked in middle-distance research design. Finally, we offer practical recommendations on how researchers, practitioners, and coaches can advance training study designs, scientific interventions, and analysis on middle-distance athletes/participants to provide information for individualized decision making trackside and more favorable and informative study outcomes.
Thesis
Full-text available
In der vorliegenden Arbeit werden die positiven Entwicklungstendenzen im Mittel- und Langstreckenlauf in den USA thematisiert. Der Autor verfolgt dabei das Ziel, Ursachen für diese Entwicklungen mittels einer systematischen Literaturrecherche herauszuarbeiten und das Konzept des Erfolges darzustellen. Hierbei wird im ersten Teil anhand von Nationenwertungen und Analysen der Jahresbestzeiten sowie der Platzierungen in den Weltjahresbestenlisten diese Entwicklung konkretisiert. Der zweite Abschnitt beinhaltet die möglichen Ursachen, wobei der Autor vorerst auf den High School und College Bereich, an-schließend auf den professionellen Hochleistungsbereich eingeht. Es konnte festgestellt werden, dass die positiven Entwicklungen geschlechts- und disziplinübergreifend sind und ihren Ursprung 2001 im Nachwuchsbereich hatten. Für den Hochleistungsbereich lässt sich der Beginn der positiven Tendenzen mit der Weltmeisterschaft 2007 festhalten. Der Autor kommt des Weiteren zu dem Ergebnis, dass sowohl trainingsmethodische, als auch leistungssportstrukturelle Ursachen auf allen Ebenen des US- amerikanischen Leistungssportsystems diese starken Steigerungsraten erklären lassen. Als Kernaspekt wird auf das Modell der Trainingszentren eingegangen, wobei der Autor im Schlussteil versucht, Anregungen für den deutschen Mittel- und Langstreckenlauf zu geben.
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The 3 factors of the classic model (maximal oxygen uptake [VO2max], fractional utilization of VO2max at the anaerobic threshold, and running economy [RE]) are well known to be the determinants of isolated distance running performance. However, no previous studies appear to have investigated the relationship between all 3 factors and running performance in the Olympic-distance triathlon (ODT). We therefore investigated this relationship by conducting 2 studies. In study I, the relationship between the 3 factors of the classic model and running performance in actual ODT races was investigated in 16 male triathletes. In study II, the relationship between the three factors and running performance in simulated ODT races with controlled exercise intensities, pedaling cadence, and carbohydrate intake during the swim and bike legs was investigated in 8 male triathletes. The 3 factors were quantified using a treadmill incremental test following the same protocol in each study. Simple correlation and multiple regression analyses were performed using the forced entry method. The independent variables were the 3 factors of the classic model, and the dependent variable was running performance in the ODT races. In study I, no significant correlation was found between the 2 measurements (p > 0.05). Furthermore, no significant multiple correlation coefficient was obtained (R < 0.54, p > 0.05), and < 10.7% of the running performance was attributable to the 3 factors. In study II, by contrast, a significant correlation was found between RE and running performance (r = 0.79, p = 0.02). In addition, a significant multiple correlation coefficient was obtained (R = 0.91, p = 0.05), and 69.9% of the running performance in the simulated ODT race was attributable to the three factors. In conclusion, we suggest that in the ODT the 3 factors of the classic model explain interindividual variation in running performance. However, in an actual ODT race, the relationship between the 3 factors and running performance may weaken owing to the residual effects of prior swimming and cycling.
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The aim of this study was to determine the possible correlations between essential and toxic trace elements of plasma with several anthropometric and body composition parameters and performance in endurance runners. Sixty-five high-level middle and long-distance runners (21 ± 3 years; 1.77 ± 0.05 m; 64.97 ± 7.36 kg; VO 2 max. 67.55 ± 4.11 mL/min/kg) participated in the present study. Abdominal, subscapular, iliac crest, triceps, front thigh and medial calf skinfold thicknesses and an incremental test until exhaustion were recorded. Body, fat, muscle and bone mass were estimated. Plasma trace elements were analyzed with inductively coupled plasma mass spectrometry (ICP-MS). Correlations and simple linear regression were used to assess the relationship between trace elements and several variables. Different skinfolds, fat mass, muscle mass and bone mass correlated positively and negatively with trace elements such as copper, manganese, selenium, vanadium, zinc, lithium, rubidium, strontium, arsenic, beryllium and lead. Lithium was related with performance. In conclusion, endurance training causes changes in the body concentrations of several trace elements that trigger modifications in body composition that may be interesting, if confirmed in the future, for the control of metabolic diseases such as obesity.
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The aim of this study was to determine the possible changes in plasma of several hormones such as Luteinizing Hormone, Testosterone, Cortisol and Insulin in endurance runners during the sports season. Twenty-one high-level male endurance runners (22 ± 3.2 years, 1.77 ± 0.05 m) participated in the study. Basal plasma hormones were measured at four moments during the season (initial, 3, 6 and 9 months), and were analyzed using ELISA (enzyme-linked immunosorbent assay). Testosterone and Luteinizing Hormone (LH) suffered very significant decreases (p < 0.01) at 3 months compared with the beginning and an increase (p < 0.05) at 6 and 9 months compared with 3 months. Insulin level was significantly lower (p < 0.05) at 3, 6 and 9 months compared with the initial test. Insulin and cortisol were associated inversely (r = 0.363; β = −0.577; p = 0.017) and positively (r = 0.202; β = 0.310; p = 0.043), respectively, with the amount of km per week performed by the runners. There was a significant association between km covered at a higher intensity than the anaerobic threshold and I (r = 0.580; β = −0.442; p = 0.000). Our findings indicate that testosterone, LH and insulin were more sensitive to changes in training volume and intensity than cortisol in high-level endurance runners. Basal testosterone and LH concentrations decrease in athletes who perform a high volume of aerobic km in situations of low energy availability.
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Khelo India School Games (KISG) an ambitious program introduced by MYAS, Govt. of India for sports excellence was launched successfully in Delhi in 2018. The mandate was to revive the sports culture in the country at the grass root level. KISG helped identifying almost 1500 talented players in the 1 st stage, which will be supported financially through developmental program for participation in international events. This paper studies the selected Khelo India Athletes and compares their performances. The analytical comparison also highlights the achievable targets with respect to timing, distance that is still to be achieved before qualifying for Olympics Games.
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In brief: American mile record holder Steve Scott was tested for maximal aerobic capacity and running economy on three occasions over nine months, a period that included off-season, preseason, the indoor season, and the early part of the outdoor season. The laboratory results demonstrated that Scott's training raised his maximal aerobic capacity approximately 8% and improved his running economy 5%. In comparing Scott's data with that of former American record holder Jim Ryun, it appears that Scott's better economy, which allowed him to perform at a lower percentage of his maximal aerobic capacity, was the essential difference between the two runners.
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The purpose of this study was to evaluate the relationship between training methods of NCAA Division I runners and 10,000-m performance. Fourteen qualifying teams of the National Collegiate Athletic Association Division I national cross-country meet and 16 randomly chosen, nonqualifying teams participated in the study. A survey was used to evaluate the training methods of the respective teams throughout the training season. The results of the study indicated that the use of speed work, fartlek, mileage, and running twice a day during the transition phase of training were associated with a slower team performance. Interval training and fartleks during the competition phase were related to a slower team performance. Intervals and tempo training during the peaking period were related to a better performance. The multiple regression equation revealed that hill training during the transition phase was related to a faster team time. The transition phase of training appears to be related to success at the end of the season.
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Train for your next race with the man who has been called “the world’s best running coach.” With more than 55 years of experience, Jack Daniels is a legendary figure in the running community. Named the National Coach of the Year by the NCAA and honored as the Division III Women’s Cross Country Coach of the Century, Daniels has mentored some of the greatest names in running, including Jim Ryun, Ken Martin, Jerry Lawson, Alicia Shay, Peter Gilmore, Magdalena Lewy-Boulet, and Janet Cherobon-Bawcom. In Daniels’ Running Formula, he has shared training advice with hundreds of thousands of runners. Now in this updated—and definitive—fourth edition, he again refines his methods and strategies to help you run faster and stronger. Building upon his revolutionary VDOT system, Daniels incorporates new insights gained from studying participants in his unique Run SMART Project. You’ll be guided through the components that make the training formula work and then learn different types of training—including treadmill training, fitness training, and training at altitude or in other challenging environments—along with age-related modifications for runners from ages 6 to 80. Everything comes together with expert advice on event-specific training ranging—for runs ranging from 800 meters to ultradistance events and triathlons. You will find advice on setting up your own seasonal plan, or you can follow one of Daniels’ 31 proven training plans and workouts. You’ll even find four fitness running plans, from novice level to elite level, to get in shape or regain conditioning after injury. Join the thousands of runners who have relied on Jack Daniels to help them reach their peak running performance. Using the programs outlined in Daniels’ Running Formula, you too can achieve the results you seek every time you train and race.
Article
To investigate the effects of simultaneous explosive-strength and endurance training on physical performance characteristics, 10 experimental (E) and 8 control (C) endurance athletes trained for 9 wk. The total training volume was kept the same in both groups, but 32% of training in E and 3% in C was replaced by explosive-type strength training. A 5-km time trial (5K), running economy (RE), maximal 20-m speed ( V 20 m ), and 5-jump (5J) tests were measured on a track. Maximal anaerobic (MART) and aerobic treadmill running tests were used to determine maximal velocity in the MART ( V MART ) and maximal oxygen uptake (V˙o 2 max ). The 5K time, RE, and V MART improved ( P < 0.05) in E, but no changes were observed in C. V 20 m and 5J increased in E ( P < 0.01) and decreased in C ( P < 0.05).V˙o 2 max increased in C ( P < 0.05), but no changes were observed in E. In the pooled data, the changes in the 5K velocity during 9 wk of training correlated ( P< 0.05) with the changes in RE [O 2 uptake ( r = −0.54)] and V MART ( r = 0.55). In conclusion, the present simultaneous explosive-strength and endurance training improved the 5K time in well-trained endurance athletes without changes in theirV˙o 2 max . This improvement was due to improved neuromuscular characteristics that were transferred into improved V MART and running economy.
Article
In Brief: Nine elite male distance runners were evaluated by comprehensive periodic monitoring of selected blood chemistry variables, percent body fat and lean body mass, and cardiopulmonary performance as they prepared for the 1984 Olympic Summer Games in Los Angeles. The most consistent changes included a decrease in percent body fat (5.4% to 4.6%, p <.05) and an increase in anaerobic threshold. Compared with a healthy, untrained group matched for age, sex, and height, the runners showed measurable differences in resting pulmonary function, including elevated pulmonary diffusing capacity, maximum voluntary ventilation, and peak expiratory flow rate. Consistent deviations in indexes of iron stores and metabolism were also noted. The extent to which such altered iron status compromises training and competitive performance or may be restored by iron supplementation needs further investigation.
Article
This paper examines the contribution of exercise physiology research to improvements in sports performance. By using illustrations from studies on competitive swimmers, attempts have been made to show the need to develop tests that evaluate the factors essential for success in sports. Such testing should be used to describe the strengths and weaknesses of the athlete, and to offer the athlete and coach valid information to gauge the benefits of training. Aside from the value of monitoring the adaptations to sports training, the primary role of physiological research in sports should be to solve problems that will ultimately aid athletes to achieve their full potential. This paper will conclude with examples of problem solving research and its contribution to performance.
Article
The use of Sorbothane shoe inserts did not significantly alter the oxygen cost of running although the cost increased at both speeds (241 and 268 m · min-1). Catlin and Dressendorfer (1979) compared the oxygen cost of running in training flats (435 g each) and racing flats (260 g each). Subjects were seven marathoners who ran at their own best marathon race pace (201 to 303 m · min-1). V̇O2 (m1 · kg1 · min-1) was increased 3.3% (p<.05) while wearing the training flats, which was equivalent to an extra 2.14 kJ · min-1. At the submaximal running speeds selected, 241 and 268 m · min-1, no significant increase in absolute (l · min-1) or relative (ml · kg-1 · min-1) V̇O2 was found. This was true whether comparing V̇O2 as an average over the 6 minutes or the sum of the 6 minutes. These data are summarized in Table 3. The differences observed were slight. The increased oxygen uptake (l · min-1) was 0.4% greater while wearing the inserts at 241 · ̇ min-1, and 1.1% greater at 268 m · min-1. This yielded an increase in kJ expended of only .25 and .80 per minute at the two speeds, respectively. Over a 1 hour duration, this would amount to an increased energy expenditure of only 15.12 kJ at 241 · min-1, and 47.0 kJ at 268 m · min-1. When expressed relative to body weight, the increase in V̇O2 was 0.9% at 241 m · min-1 and 1.5% at 268 m · min-1.
Article
Seven female members of a university cross‐country and track team (mean age, height, and weight were 19.4 years, 160 cm, and 52.7 kg, respectively) were physiologically monitored through 1 year of training and competition. Laboratory assessment included measurement of maximal oxygen uptake (VO2max), ventilation threshold (VT), running economy, percent body fat, elapsed time to exhaustion at VO2max on a treadmill run, and peak grade (PG) reached on a treadmill test. Physical performance was based on elapsed time for completing the same 5 km cross‐country course at the identical time each year. A statistically significant change was noted in only two variables: elapsed time of treadmill running at VO2max (p 0.03) and 5 km run time (p = 0.04). Two variables were significantly related to 5 km run performance: PG (r = ‐0.925) and speed at VT (r = ‐0.829). The relationship of VO2max and run time was not significant (r = ‐0.287, p >0.05). The change in only one variable, percent body fat, was significantly related to change in run time (r = ‐0.82). It was concluded that a change in VO2max, VT, and running economy is not required in order for running performance to improve. Performance in running 5 km was strongly related to speed at VT and PG achieved at VO2max, whereas improvement in performance was best explained by decreased body fat.