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Abstract

Training intensity distribution is important to training program design. The zones 1 to 2 boundary can be defined by the Talk Test and the rating of perceived exertion. The zones 2 to 3 boundary can be defined by respiratory gas exchange, maximal lactate steady state, or, more simply, by critical speed (CS). The upper boundary of zone 3 is potential defined by the velocity at maximum oxygen uptake (vVO2max), although no clear strategy has emerged to categorize this intensity. This is not normally definable outside the laboratory. Purpose: This study predicts vVO2max from CS, determined from 1 (1.61 km) and 2 (3.22 km) citizen races in well-trained runners. Methods: A heterogeneous group of well-trained runners (N = 22) performed 1- and 2-mile races and were studied during submaximal and maximal treadmill running to measure oxygen uptake, allowing computation of vVO2max. This vVO2max was compared with CS. Results: vVO2max (4.82 [0.53] m·s-1) was strongly correlated with CS (4.37 [0.49] m·s-1; r = .84, standard error of estimate [SEE] = 0.132 m·s-1), 1-mile speed (5.09 [0.51] m·s-1; r = .84, SEE = 0.130 m·s-1), and 2-mile speed (4.68 [0.49] m·s-1; r = .86, SEE = 0.120 m·s-1). Conclusions: CS, calculated from 2 citizen races (or even training time trials), can be used to make reasonable estimates of vVO2max, which can be used in the design of running training programs.
Simple Approach to Dening Training Intensity
in Endurance Runners
Carl Foster,
1
Renato Barroso,
2
Daniel Bok,
3
Daniel Boullosa,
4
Arturo Casado,
5
Cristina Cortis,
6
Jos J. de Koning,
1,7
Andrea Fusco,
6
and Thomas Haugen
8
1
Department Exercise and Sports Science, University of WisconsinLa Crosse, La Crosse, WI, USA;
2
Department of Sports Science, University of Campinas,
Campinas, SP, Brazil;
3
Faculty of Kinesiology, University of Zagreb, Zagreb, Croatia;
4
Integrated Institute of Health, Federal University of Mato Grosso do Sul, Campo
Grande, Brazil;
5
Center for Sport Studies, Rey Juan Carlos University, Madrid, Spain;
6
Department of Human Sciences, Society and Health, University of Cassino and
Lazio Meridionale, Cassino, Italy;
7
Department of Human Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, the Netherlands;
8
School of Health Sciences, Kristiana University College, Oslo, Norway
Training intensity distribution is important to training program design. The zones 1 to 2 boundary can be dened by the Talk Test
and the rating of perceived exertion. The zones 2 to 3 boundary can be dened by respiratory gas exchange, maximal lactate steady
state, or, more simply, by critical speed (CS). The upper boundary of zone 3 is potential dened by the velocity at maximum oxygen
uptake (vVO
2
max), although no clear strategy has emerged to categorize this intensity. This is not normally denable outside the
laboratory. Purpose:This study predicts vVO
2
max from CS, determined from 1 (1.61 km) and 2 (3.22 km) citizen races in well-
trained runners. Methods:A heterogeneous group of well-trained runners (N = 22) performed 1- and 2-mile races and were studied
during submaximal and maximal treadmill running to measure oxygen uptake, allowing computation of vVO
2
max. This vVO
2
max
was compared with CS. Results: vVO
2
max (4.82 [0.53] m·s
1
) was strongly correlated with CS (4.37 [0.49] m·s
1
;r= .84, standard
error of estimate [SEE] = 0.132 m·s
1
), 1-mile speed (5.09 [0.51] m·s
1
;r= .84, SEE = 0.130 m·s
1
), and 2-mile speed (4.68
[0.49] m·s
1
;r= .86, SEE = 0.120 m·s
1
). Conclusions: CS, calculated from 2 citizen races (or even training time trials), can be used
to make reasonable estimates of vVO
2
max, which can be used in the design of running training programs.
Keywords:critical speed, vVO
2
max, training program design
Performance in endurance athletes typically improves with
systematic training.
14
Together, volume and intensity of training
(LOAD) are the likely driver of adaptive responses. There is
consensus that a substantial (approximately 70%80%) percentage
of either training days or cumulative minutes should be performed
at relatively low intensities (zone 1, [z1]; <VT1/LT1).
5,6
There is
debate regarding how the remaining (approximately 20%30%) of
training should be conducted. The literature suggests that intensi-
ties between VT1/LT1 and VT2/LT2 (at/below maximal lactate
steady state [MLSS] or critical speed/power [CS]) represents an
important training zone (z2).
2,5,6
Training at a [blood lactate] of
4 mmol·L
1
has been thought to have large benets.
7
Other
literature and tradition suggests that training at intensities between
VT2/LT2, MLSS, CS/critical power, and velocity at maximum
oxygen uptake (vVO
2
max; z3) is benecial both diagnostically and
prescriptively.
8,9
Truly supramaximal intensities, representing a
low percentage of training volume, are typically included in z3 on
the basis that there is no clear denitional basis for this very high-
intensity training, which for most athletes represents a very small
percentage of the training load.
Granted that training in particular zones may have unique
effects, and that the ideal training intensity distribution remains
debated
5,6
there remains the problem of identifying training zones.
Many coaching groups have consensus recommendations regard-
ing the %maximum oxygen uptake (VO
2
max), %maximal heart
rate, [blood lactate], and rating of perceived exertion (RPE) in
various training zones.
2
Landmarks relating to training zones, often
called intensity domains, often depend on laboratory testing.
Although laboratory testing can help dene training zones, it is
not widely available, except to elite athletes. Accordingly, strate-
gies for dening training zones and vVO
2
max using less techno-
logically demanding methods have been developed.
Training in z1 can be dened using either the talk test or
RPE.
10
Exercising at intensities where speech is still comfortable
and where RPE is 4/14, depending on whether category ratio-10
or classical Borg scales are used, is associated with physiological
responses consistent with z1. Although a driftduring prolonged
exercise bouts must be accounted for, the talk test and RPE remain
useful markers of z1.
Training in z2 is marked by training at/below the speed
associated with the MLSS (or more optimally the CS
11
), or by
talk test responses where speech is not comfortablebut is still
possible, with RPE in the range of 5 to 6/15 to 16.
10
Although there
are highly specic methods of estimating the CS from laboratory
runs, recent evidence has shown that 2 to 3 time trials, performed as
part of normal training or races, can approximate CS.
12
Although
there is not a universally agreed upon denition of the top of z2,
Galan-Rioja et al,
13
recently published a systematic review meta-
analysis that shows: CS/critical power is in the same general
intensity window that also contains the MLSS, the VT2 and the
LT2, all of which have been proposed as the top of z2. Given that
CS is relatively easy to measure parameter of the broad concept of
the maximal metabolic steady state, we chose to use it in this study.
Training in z3 is problematic. Clearly, while the CS, the talk
test category of speech is denitely not comfortableand a RPE
approximately 6/16 can provide a lower limit of z3, there is not an
accepted method of dening vVO
2
max outside the laboratory. The
velocity at VO
2
max has been associated with the average velocity
in running races of approximately 3 km, with velocity sustainable
Foster (cfosteruwl@gmail.com) is corresponding author.
1
International Journal of Sports Physiology and Performance, (Ahead of Print)
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for 4 to 8 minutes in constant speed laboratory runs, or with
velocity associated with the highest achievable velocity during
incremental track runs. However, a single strategy to estimate
vVO
2
max outside the laboratory is not widely accepted. Since CS
and vVO
2
max are both integrated markers of aerobic metabolism
and the cost of running, it would seem that estimating vVO
2
max
from CS, which can be derived from as few as 2 timed trials
conducted as a normal part of training might be a viable strategy.
12
This study was designed to create estimates of vVO
2
max from time
trial-derived CS in well-trained recreational runners.
Methods
The subjects for this study were 22 recreational runners, tier 2 in the
classication of McKay et al.
14
Their age, height, and weight (mean
[SD], range) were 35.2 (8.6), 24 to 51 years; 179.5 (5.9), 172 to
193 cm; and 69.6 (7.0), 60 to 81 kg, respectively. All had 2 years of
experience in competitive running, trained systematically (5d·wk
1
),
competed 15 times per year (mostly 5- to 10-km citizen races), and
approximately 70% completed a marathon ±1 year from the time of
study. Training was primarily steady runs (61 [31] km·wk
1
)at
moderate intensity (74% [8%] VO
2
max). Tempo or interval training
was infrequent (1wk
1
), although most raced at least every other
week. All subjects provided written informed consent, and the local
human subjects committee approved the protocol.
Subjects were studied in the laboratory during submaximal
treadmill running (1% elevation) during 3 to 4 speeds sustained
for 6 minutes, and during maximal treadmill running (last sub-
maximal speed +1% elevation increase per minute, until fatigue).
Submaximal speeds were individually chosen, ranging from their
estimated marathon velocity to their approximate 10-km velocity.
VO
2
max was accepted as the highest 30-second VO
2
observed
during the run to fatigue. Individual regression lines were extrap-
olated to the individual VO
2
max (vVO
2
max). Gas analysis was
accomplished using open-circuit spirometry with volume ana-
lyzed by water displacement (Tissot spirometer) and gas con-
centrations by chemical volumetric methods (Lloyd-Galenkamp).
A schematic of the computation of vVO
2
max is presented in
Figure 1.
Subjects performed citizen races, either on the track or certied
road courses, of 1 (1.61 km), 2 (3.22 km), 3 (4.83 km), 6 (9.66 km),
and 10 (16.1 km) miles. Races were performed in the Fall and Winter
under favorable environmental circumstances (10 °C to 20 °C, dry,
minimal wind). Only one race was performed on a given day.
Because of the heterogeneous running ability among the subjects,
the pacing pattern was to run at the individual best pace achievable,
which can be characterized as time trialsrather than races.
CS was calculated from the 1- and 2-mile races, based on the
principle that CS is best determined in efforts between 2- and
20-minute duration. In cases where there were missing race data
(9%), surrogate values were derived from individual timedistance
curves (110 miles [1.616.1 km]). A schematic of the computa-
tion of CS is presented in Figure 1.
Results
Individual comparisons of CS and vVO
2
max are presented in
Figure 2. Furthermore, comparisons between 1- or 2-mile velocity
and vVO
2
max are presented in Figure 2.
The subjects were representative of recreational runners.
VO
2
max (mean [SD], range) was 61.2 (7.0), 49 to 73 mL·kg
1
·min
1
;
cost of running was 202 (12), 181 to 220 mL·kg
1
·km
1
; CS was 4.37
(0.49),3.58to5.24m·s
1
;vVO
2
max was 4.82 (0.54), 3.72 to
5.85 m·s
1
; and 10-km personal record (as a referent of running
ability) was 39:06 (4:26), 30:58 to 48:16 minutes:seconds. Velocities
for 1- and 2-mile performances were 5.09 (0.51), 4.34 to 6.39 and
4.68(0.49),3.97to5.67m·s
1
, respectively.
There were strong correlations between CS (r= .84), 1-mile
velocity (r= .84), and 2-mile velocity (r= .86) with vVO
2
max. In
all cases, the standard error of estimate (SEE) was low (0.132,
0.130, and 0.128 m·s
1
) for CS, 1- and 2-mile velocity, respec-
tively. The slope of the regression of vVO
2
max on CS was nearly 1,
with average vVO
2
max being 10% faster than CS.
Discussion
The main nding of this study was that either CS, computed from 1-
and 2-mile time trials, or the average velocity of either the 1- or 2-mile
Figure 1 (Left) Schematic computation of a subject with a VO
2
max of 60.2 mL·min
1
·kg
1
. With the observed values for VO
2
during submaximal
running, the computed vVO
2
max is 4.86 m·s
1
. (Right) Schematic computation of CS from 1- (1.61 km) and 2-mile (3.22 km) time trials. In this case, the
time trials (eg, races) were performed on separate days, but they can also be performed in a single training bout with approximately 30-minute recovery.
12
The slope of the time-versus-distance graph represents the CS in meters per second. CS indicates critical speed; VO
2
max, maximum oxygen uptake;
vVO
2
max, velocity at VO
2
max.
2Foster et al
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time trials could be used to estimate vVO
2
max. Thus, a simple
performance-based protocol, without the necessity of measuring gas
exchange, [blood lactate], or heart rate can be used to generate
benchmark values for CS and vVO
2
max, which are important markers,
both diagnostically and prescriptively, of the z2 to z3 transition
velocity, and the potentially unique velocity of vVO2max. Velocities
greater than vVO
2
max can be taken either as above z3, or within cz3,
but in any case represent a comparatively small quantity of training.
Given the relatively small SEE generated by the regression
formulae, the average subject (CS = 4.37 m·s
1
), would run 3:04 for
800 m, 3:49 for 1000 m, 4:33 for 1200 m, or 5.1 km in 20 minutes, as
suggested by Sjodin.
7
Similarly, the same average subject would
have vVO
2
max of 4.81 m·s
1
, and would run 2:46 for 800 m, 3:28 for
1000 m, or 4:09 for 1200 m. At ±1 SEE, the estimated vVO
2
max
would be 4.95 and 4.69 m·s
1
, representing 2:42 and 2:51 for 800 m,
3:22 and 3:33 for 1000 m, or 4:02 and 4:16 for 1200 m. Although the
Figure 2 (Left) Regression relationship between the speed of vVO
2
max and CS determined from 1- and 2-mile time trials and from average speed in
1- and 2-mile time trials individually. The vVO
2
max is 110% relative to the CS, 94% relative to 1-mile speed and 102% relative to 2-mile speed. (Right)
BlandAltman plots showing the bias in vVO
2
max and speed of CS and 1- and 2-mile speed. CS indicates critical speed; VO
2
max, maximum oxygen
uptake; vVO
2
max, velocity at VO
2
max.
Simple Approach to Training Intensity 3
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time limit for vVO
2
max was not measured in this study, it is thought
to be in the range of 4 to 8 minutes, with 6 minutes as a central
value.
8,9
Accordingly, a scheme of 5 to 8 ×800 to 1200 m@vVO
2-
max with 400 m of slow recovery jogging (approximately 3 min)
would t within the parameters suggested by Billat
8
and Midg-
ley et al.
9
The 1-and 2-mile time trials resulted in slightly higher correla-
tions and slightly smaller values for SEE for vVO
2
maxandcouldbe
used alternatively to CS as the referent. However, as training at or just
slower than CS (z2) is also considered an important index relative to
designing training programs, it seems that a single procedure that
generates both CS and vVO
2
max would be more effective than using
time trials of 1 or 2 miles to estimate vVO
2
max alone.
Practical Implications
These results suggest a strategy for generating training intensity
landmarks without the necessity for laboratory testing. These
landmarks may be useful both diagnostically and prescriptively.
Furthermore, successive repetitions of the 2 distance time trials
used to estimate CS and be used periodically as a marker of training
velocity progression, without the perception that training time is
being lost to testing. The present results suggest that generating CS
and vVO
2
max landmarks is fairly easy, which makes a science
driven approach to training program design more accessible to
coaches and their athletes.
Conclusions
The results suggest that a simple, performance-based, estimate of
CS can also be used to make a reasonable estimate of vVO
2
max.
Together, these 2 indices can be used to dene the z2 to z3
transition (CS) and the upper limit of z3 (vVO
2
max, approximately
CS 1.10), which may be useful in terms of training program design.
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Casado, A, Hanley, B, Santos-Concejero, J, and Ruiz-Pérez, LM. World-class long-distance running performances are best predicted by volume of easy runs and deliberate practice of short-interval and tempo runs. J Strength Cond Res 35(9): 2525-2531, 2021-The aim of this novel study was to analyze the effect of deliberate practice (DP) and easy continuous runs completed by elite-standard and world-class long-distance runners on competitive performances during the first 7 years of their sport careers. Eighty-five male runners reported their best times in different running events and the amounts of different DP activities (tempo runs and short- and long-interval sessions) and 1 non-DP activity (easy runs) after 3, 5, and 7 years of systematic training. Pearson's correlations were calculated between performances (calculated using the International Association of Athletics Federations' scoring tables) and the distances run for the different activities (and overall total). Simple and multiple linear regression analysis calculated how well these activities predicted performance. Pearson's correlations showed consistently large effects on performance of total distance (r ≥ 0.75, p < 0.001), easy runs (r ≥ 0.68, p < 0.001), tempo runs (r ≥ 0.50, p < 0.001), and short-interval training (r ≥ 0.53, p < 0.001). Long-interval training was not strongly correlated (r ≥ 0.22). Total distance accounted for significant variance in performance (R2 ≥ 0.57, p < 0.001). Of the training modes, hierarchical regression analysis showed that easy runs and tempo runs were the activities that accounted for significant variance in performance (p < 0.01). Although DP activities, particularly tempo runs and short-interval training, are important for improving performance, coaches should note that the non-DP activity of easy running was crucial in better performances, partly because of its contribution to total distance run.
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