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The cross-training (XT) hypothesis suggests that despite the principle of specificity of training, athletes may improve performance in one mode of exercise by training using another mode. To test this hypothesis we studied 30 well-trained individuals (10 men, 20 women) in a randomized longitudinal trail. Subjects were evaluated before and after 8 weeks of enhanced training (+10%/week), accomplished by adding either running (R) or swimming (XT) to baseline running, versus continued baseline running (C). Both R (-26.4s) and XT (-13.2s) improved time trial (3.2 km) performance, whereas C did not (-5.4s). There were no significant changes during treadmill running in maximum oxygen uptake (VO2peak; -0.2, -6.0, and +2.7%), steady state submaximal VO2 at 2.68 m.s-1 (-1.2, -3.3 and +0.2 ml.kg-1.min-1), velocity at VO2peak (+0.05, +0.25 and +0.09 m.s-1) or accumulated O2 deficit (+11.2, -6.1 and +9.4%) in the R, XT or C groups, respectively. There was a significant increase in velocity associated with a blood lactate concentration of 4 mmol.l-1 in R but not in XT or C (+0.32, +0.07 and +0.08 m.s-1). There were significant changes in arm crank VO2peak (+5%) and arm crank VO2 at 4 mmol.l-1 (+6.4%) in XT. There was no significant changes in arm crank VO2peak (+1.3 and -7.7%) or arm crank VO2 at 4 mmol.l-1 (+0.8 and +0.4%) in R or C, respectively. The data suggest that muscularly non-similar XT may contribute to improved running performance but not to the same degree as increased specific training.
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Eur J Appl Physiol (1995) 70:367-372 © Springer-Verlag 1995
Carl Foster Lisa L. Hector Ralph Welsh
Mathew Schrager Megan A. Green Ann C. Snyder
Effects of specific versus cross-training on running performance
Accepted: 7 August 1994
Abstract The cross-training (XT) hypothesis suggests
that despite the principle of specificity of training,
athletes may improve performance in one mode of
exercise by training using another mode. To test this
hypothesis we studied 30 well-trained individuals (10
men, 20 women) in a randomized longitudinal trail.
Subjects were evaluated before and after 8 weeks of
enhanced training (+10%/week), accomplished by
adding either running (R) or swimming (XT) to baseline
running, versus continued baseline running (C). Both
R (- 26.4s) and XT (-13.2s) improved time trial
(3.2 km) performance, whereas C did not (-5.4s).
There were no significant changes during treadmill
running in maximum oxygen uptake (VO2peak; -- 0.2,
--
6.0, and + 2.7%), steady state submaximal lzO2 at
2.68m's -1 ( - 1.2, - 3.3 and + 0.2 ml'kg-l-min-1),
velocity
at gO2pea k (
+ 0.05, + 0.25 and
+ 0.09 m' s -a) or accumulated 02 deficit (+ 11.2,
- 6.1 and + 9.4%) in the R, XT or C groups, respec-
tively. There was a significant increase in velocity asso-
ciated with a blood lactate concentration of
4 mmol- 1-1 in R but not in XT or C ( + 0.32, + 0.07
and + 0.08 m" s- 2). There were significant changes in
arm crank l/O2ve~k (+ 5%) and arm crank 1)O2 at
4 mmol" 1-1 ( + 6.4%) in XT. There was no significant
changes in arm
crank gO2pea k ( -~-
1.3 and - 7.7%) or
arm crank 1/O2 at 4 mmol" 1-1 ( + 0.8 and + 0.4%) in
R or C, respectively. The data suggest that muscularly
non-similar XT may contribute to improved running
performance but not to the same degree as increased
specific tranining.
Key words Cross-training l/O2veak " Running
Lactate. Oxygen deficit
C. Foster (N~) - L.L. Hector. R. Welsh. M. Schrager
M.A. Green ' A.C. Snyder
Human Performance Laboratory, Milwaukee Heart Institute,
P. O. Box 342, Milwaukee, WI 53201-0342, USA
Introduction
Systematic exercise training is associated with en-
hanced exercise performance in both previously seden-
tary individuals and athletes. Improved performance is
usually thought to be related to the magnitude of the
training stimulus and to be fairly specific to the type of
training undertaken.
Beginning in the early 1980s, with the emergence of
the triathlon, many single-sport athletes noted that
they performed remarkably well in their previous
specialty events despite reduced specific training to
allow for multi-event training. The concept emerged
that the non-specific training provided a "crossover
benefit" relative to general fitness. At about the same
time, recognition of the importance of both aerobic and
resistance training to the fitness participant, and an
increased number of middle-aged participants desiring
to minimize orthopedic consequences of single-mode
training, created interest in multi-event training. Ac-
cordingly the concept of "cross-training" emerged. It is
now fairly well accepted that multi-mode training has
a role for not only the general fitness participant but
also in maintaining general conditioning in athletes
during reductions of training associated with injury or
regeneration cycles.
Despite studies demonstrating the value of non-spe-
cific training in previously sedentary individuals (Lewis
et al. 1980; McArdle et al. 1978; Pollock et al. 1975)
there are comparatively few data regarding the value of
non-specific training in athletes. Loy et al. (1993) and
Mutton et al. (1993) have demonstrated significantly
improved running performance from either stair-
climbing exercise or combined run/cycle training that
were generally comparable to run-only training. Thus,
there appear to be data to support the concept that
non-specific, but muscularly similar, training may con-
tribute to enhanced running performance. At this time
there are virtually no data concerning the responses to
368
non-specific, and muscularly dissimilar, training (e.g.
swimming for runners). The concept of the "lactate
sink" (Stainsby and Brooks 1990) would suggest that
endurance training of muscle fibers not active during
running might reduce the magnitude of lactate accumu-
lation during running and, accordingly, contribute to
enhanced performance (Sjodin et al. 1982). Accord-
ingly, the purpose of this study was to evaluate the
effect of muscularly dissimilar non-specific training
(swimming) on running performance, and its physiolo-
gical correlates.
Methods
The subjects for this study were 30 volunteers (10 men, 20 women).
All provided informed consent prior to participation. Mean (SD)
characteristics of the subjects at the onset of training are presented in
Table 1. Although all of the subjects were previously well trained
and most had some experience in local running events, none were
serious competitive runners. During the 2 months prior to being
recruited for the study, the amount of running training ranged from
15 to 80 km week- 1.
Following recruitment, the subjects engaged in 8 weeks of baseline
training consisting of 30 min running at a moderate pace 5 days
weekly (25-30 km week- 1). This period was intended to ensure that
differences in training prior to recruiting the subjects were mini-
mized and that the level of training was consistent in all subjects
prior to application of the experimental intervention. After this
8-week baseline period, the subjects performed the first set of tests
and were randomized to one of three intervention groups. After
8 weeks of intervention, the subjects performed the second set of
tests.
Evaluation consisted of a 3.18-km (2-mile) running time trial held
on an indoor 201.2 m track, laboratory tests of peak oxygen uptake
(1202p~ak) and blood lactate accumulation, designed to elicit the
running velocity associated with a blood lactate concentration of
4 mmol" 1 1 (v4 mmol" 1-1), accumulated oxygen deficit (~O2 defi-
cit), running economy (at 2.68 m" s-1), and the velocity requiring
a 1202 equal
to VO2peak(/)VO2peak)
during treadmill running. Addi-
tionally 12Ozp~a k and
V02
at 4 mmol" 1-1 during arm crank exercise
were measured.
In order to minimize the influence of competitive experience, each
subject performed two time trials during each evaluation period.
Training during the day preceding each time trial was subjectively
easy. Each time trial was conducted without competitive assistance
from other runners. Lap times were provided throughout each trial.
The faster time trial during each evaluation period was accepted as
the criterion measure for that subject.
Blood lactate accumulation was evaluated using an enzyme elec-
trode system in capillary blood obtained from a warm fingertip
following steady velocity runs (4-6 rain) on the treadmill at 5%
elevation. The velocity during these runs was 2.2 m' s- 1 during the
first run and was increased by 0.2-0.3 m.s -1 during successive
stages. The duration of each ru n (beyond 4 min) was determined by
observing on-line plots of 1)'O2 and continuing the stage until a clear
steady state of 12Oz was observed. In order to facilitate blood
sampling, successive stages were separated by 1 min of walking at
1.3 m' s-
1 0% grade. Successive stages were performed at least until
the rating of perceived exertion (RPE) for that stage equaled 5 on the
category ratio Borg scale (Borg et al. 1987). This scale was slightly
modified by changing the verbal anchors into idiomatic American
English. For example the term "severe," which is the verbal anchor
for a rating of 5, was changed to "hard." We have found that this
slight modification of the scale greatly improves its clinical utility
(Foster 1988). v4mmol.1-1 was accepted as the index of blood
lactate accumulation. These steady-state runs were also used to
calculate the 1202 requirement of running to allow subsequent
calculation of running economy (the 1202 at 2.68 m" s- 1) and the
ZO2 deficit (Medbo et al. 1988). Following a 15-min recovery period
of slow walking/stretching after the last submaximal run, l?O2pe, k
was measured as the highest full minute 1202poa k during an uphill
(5% grade) running bout designed to allow measurement of the ZO2
deficit. The velocity during this bout was set at 0.9 m" s- 1 faster than
the velocity associated with an RPE of 5 (hard) during the submaxi-
mal runs. Pilot studies in our laboratory demonstrated that this
scheme for choosing velocity consistently caused the subjects to
become fatigued within 2-5 min. The ~O2 deficit was calculated
according to the procedure outlined by Medbo et al. (1988). The
1702 requirement was calculated from the submaximal steady-state
runs designed to measure v4 mm and running economy, extrapo-
lated to the velocity used during the maximal run. The ~O2 con-
sumed during this run was subtracted from ZO2 requirement to
compute ZO2 deficit. The vl2Ozp~, k was calculated by extrapolating
the submaximal velocity-l?Oz relationship to the l)'O2p~a k. Although
an independent measurement of 1202po, k using a conventional in-
cremental protocol and leveling off criteria were not used, the
protocol used in this study resulted in measured 1202 that was
consistently less than predicted from the submaximal studies, in
a respiratory exchange ratio greater than 1.10, heart rates within 5 %
of age-predicted maximal, and post-exercise blood lactate concen-
trations in excess of 10 mmol'l-1. On the basis of studies in our
laboratory demonstrating the behaviour of 1202poa k during non-
incremental protocols (Foster et al. 1993), we felt that the l?Ozpo, k
value thus achieved was likely to be comparable with that obtained
with a conventional exercise protocol.
Blood lactate accumulation during arm ergometry was evaluated
from blood lactate measurements obtained during arm crank exer-
cise with progressive 4-min stages. A 30-s break between stages was
allowed to facilitate blood sampling. During this bout, resistance on
the flywheel of the ergometer was adjusted to 10 N (males) and
5 N (females) on the basis of pilot studies. Power output during
successive stages was varied by changing cranking frequency. Arm "
~ZOzpea k was the highest
VO 2
during a bout where the subject
attempted to complete 200 revolutions of the arm crank as rapidly as
Table 1 Mean (SD) characteristics of the subjects of baseline
Age Height Weight % Fat
(years) (m) (kg)
TREADMILL ARM Crank
VO2pea k V4 mmol.1
1 ~Ozpea k
VO 2 at mmol'l- 1
(ml kg- 1) (m. s- 1) (min- 1)
Men 34.2 1.77 76.3 15.9
(11.9) (0.05) (6.7) (4.7)
Women 24.6 1.67 58.8 17.9
(5.0) (0.07) (7.2) (4.2)
54.9 2.66 2.78 1.44
(6.5) (0.29) (0.38) (0.22)
52.4 2.52 1.91 1.21
(5.0) (0.28) (0.27) (0.23)
possible. The subject was instructed to start cranking as rapidly as
possible and to complete 200 revolutions in minimal time. At the
level of flywheel resistance used in this study, 200 revolutions at
maximal effort usually required about 2 min. We have previously
demonstrated that self-paced trials of this nature are very effective in
eliciting peak physiological responses in athletes (Foster et al. 1993).
The three randomly assigned intervention groups included a con-
trol group (n = 11), an enhanced running group (n = 9) and a cross-
training group (n = 10). The control group continued running
30 rain daily at a moderate pace, 5 days weekly. The enhanced
running group increased their running training by about 10% per
week. They completed eight training sessions during 6 days per week
including both interval and continuous running. The cross-training
group continued running 30 min daily at a moderate pace, 5 days
weekly. However, they increased their training frequency to eight
sessions during 6 days per week by adding three swimming sessions
per week to their running program, with the intent of having the
same total training load as the enhanced running group.
Training was quantitated by a modification of the method de-
scribed by Banister et al. (1986), which multiplies training intensity
by duration to create a training impulse score for each training
session• Because of practical difficulties in obtaining heart rate for
every training session in a large group of subjects and because of
concerns about the ability of heart rate to represent the training load
during interval exercise, we used the perceived exertion scale of Borg
et al. (1987) and asked the subject to rate their effort for the entire
training session. This is an extrapolation of the wide clinical use of
the perceived exertion scale as an adjunct to heart rate. The "ses-
sion" RPE was multiplied by the total duration of training (in
minutes) to create a training impulse score, which we refer to as
100 .....
t e/ r=0.65
901 .. /
=
t
"-/'
° 01
¢¢
:]/..
e
60 . ~ . i . i , D - i . i i J i
0 1 2 3 4 5 6 7 8 9 10
Session RPE
Fig. 1 Comparison of the rating of perceived exertion
(RPE)
for
a 30-min steady-state running training session and the mean per-
centage heart rate reserve during that training session, r = 0.65
369
training load. In pitot studies there was a moderate correspondence
between average percentage heart rate reserve during 30-min
steady-state runs and the "session" RPE (Fig. 1). Following sugges-
tions that indices of lactate accumulation (and associated heart
rates) could be used to control training intensity (Coen et al. 1991;
Gihnan and Wells 1993; McLellan and Skinner 1981), we also
evaluated the relationship of the "session" RPE to the percentage of
time spent below, between and above commonly used blood lactate
transition zones (2,5 and 4.0retool.1-1) during 30-rain training
sessions (Fig• 2). These sessions included both interval and continu-
ous exercise. There was a good correspondence between the training
"session" RPE and the behavior of heart rate in relation to the
common blood lactate transition zones. Accordingly, we felt that the
training "session" RPE method provided approximately the same
information regarding the relative training intensity as the method
of Banister et al. (1986) which relies on continuous measures of heart
rate.
Statistical comparisons were made amongst the intervention
groups using repeated measures ANOVA. A Scheffe test was used
for post hoc comparisons. A P value of < 0.05 was accepted as
statistically significant.
Results
There were no significant differences amongst the three
groups prior to intervention in any of the primary
outcome measures. As per the experimental design, the
mean (SD) 8-week training load increased significantly
and similarly in the enhanced running [509 (24) to 695
(108)-week -t) and cross-training [519 (21) to 835
(126)" weak-t) groups and did not change in the con-
trol group [576 (14) to 549 (21) week-1). The overall
increase in load in the enhanced running and cross-
training groups represented 7.1% and 10.3 % increases
per week of intervention, respectively. The increase in
training load was dominantly by an increase in training
duration in both the enhanced running and cross-train-
ing groups. There was a non-significant trend for in-
creases in training volume to predominate in the cross-
training group and training intensity to predominate in
the enhanced running group (Fig. 3).
Time trial performance improved significantly in
the enhanced running group (- 26.4 s) and in the
IOQ
90"
80"
¢¢ 7Q"
,J
A: Blood
Lactate < 2.5 rnmol*l-1
/ : ~ : : :
1 2 3 4 5 8 7 8 0 10
Sesaton RPE
B: Blood Lactate
Between 2.5
& 4.0
mmoPl-1
100
80
8O
68 |
50
40
30
20
10
0 1 2 3 4 5 6 7 8 9
Session
RPE
100
90
80
¢ 70,
0 80
so.
2(1"
10"
10
C: Blood Lactate
> 4,0 mmot'l-1
II
1 2 3 4 5 6 7 8 0 10
Seaslorl RPE
Fig. 2A-C Comparison of RPE for a 30-min running training session (including both steady state and interval sessions) versus: A the
percentage of time the heart rate is below that associated with a blood lactate concentration of 2.5 mmol. 1-1; B the percentage of time the
heart rate is between that associated with blood lactate concentrations of 2.5 and 4.0 mmol. 1 - 1, and C the percentage of time the heart rate is
above that associated with a blood lacatate concentration of 4.0 mmol. 1-1
370
1500
1000
.J
500
0
0
TRAINING LOAD
ENHANCED RUNNING
---II--- CROSS TRAIN
--'O-- CONTROL
Baseline
4
intervention
8 12 16
WEEK
,K
,.=
E
O
G
C~
_=
._=
300
250 -
200
150
Training Duration Training Intensity
o.
E 4
O
2'
E
.E
. . , . . , . . , . . . ~_ ~ ,
100 0
i
1 p M L q M
4 8 12 16 0 4 12 16
WEEK WEEK
Fig. 3A-C Schematic representations of the average training load duirng baseline and intervantion periods. Training Load (dimensionless
units) was computed as the weekly summation of daily duration (in minutes) multiplied by the session RPE for each day's training session.
Although the cross-training group (--M--) had somewhat greater training duration during the intervention period than the enhanced
running group (re--), training load was counterbalanced by a somewhat greater training intensity in the enhanced running group. There
were no statistically significant differences in training load between the enhanced running and cross-training groups. ~O--) Control
group
cross-training group (- 13.2 s). There was no signifi-
cant change in time trial performance in the control
group (-5.4 s) (Table 2). The change in time trial
performance was significantly greater in the enhanced
running group than in the cross-training group. Com-
pared to pre-randomization values, post-training time
trial performance decreased 3.2%, 1.4% and 0.6% in
enhanced running, cross-training and control groups,
respectively (Fig. 4).
v4 mmol' 1-1 increased significantly in the enhanced
running group but did not change in the cross-training
or control groups (Table 2). There was no significant
change in treadmill running 1202pe,k, running econ-
omy, V1202peak, or ~O2 deficit in the enhanced running,
cross-training and control groups, respectively.
There was no significant change in l)O2p~ak during
arm crank exercise in the enhanced running or control
groups. VO2wak during arm crank exercise increased
significantly in the cross-training group. There was no
significant change in the 1202 at 4 mmol-1-1 during
arm crank exercise in the enhanced running or control
groups. The 1202 at 4 mmol'1-1 during arm crank
exercise increased significantly in the cross-training
group.
Discussion
The main finding of this study is that muscularly dis-
similar non-specific training (swimming) significantly
improves running performance in well-trained recre-
ational runners. The improved running performance
with cross-training was significantly less, however, than
with increased running training. Our results are consis-
tent with previous reports of improved running perfor-
mance associated with muscularly similar non-specific
training, e.g. stair-climbing, cycling (Loy et al. 1993;
Mutton et al. 1993).
Despite significant changes in physiological re-
sponses during arm crank exercise consistent with an
upper extremity training response, there were only
371
Table 2 Mean (SD) pre and post-intervention results
(TDM 120=,, v4
mmol' 1-1 running velocity associated with blood lactate concen-
tration at 4 mlnol. 1-1, 1202 oxygen uptake, 20~
deficit
accumulated oxygen deficit,
v gO2pea k
velocity requiring peak [] 1202;
AC (/02peak,
AC
1202 4 mmol ' 1- ~.
Enhanced running Cross-training Control
Pre Post Pre Post Pre Post
Time trial 13.88 (1.50) 13.44 (1.4) am 14.77 (0.88) 14.56 (1.29) a 14.69 (1.59) 14.60 (1.52)
(rain)
TDM 1202~eak 58.0 (6.3) 57.9 (5.6) 53.6 (50.4) 50.4 (5.9) 53.5 (6.2) 55.1 (5.6)
(ml" min- 1 .kg- 1)
v4 mmol" 1-1 2.68 (0.26) 2.90 (0.28) a'b 2.49 (0.31) 2.56 (0.21) 2.56 (0.29) 2.65 (0.34)
(m" s -1)
1)'02 at 2.68 re's-1 45.4 (4.0) 44.3 (2.9) 45.5 (2.8) 42.2 (3.0) 44.3 (2.8) 44.5 (3.2)
(ml- min- 1. kg- 1)
202 deficit 44.8 (11.5) 49.8 (11.9) 42.5 (5.3) 40.8 (10.8) 44.7 (17.9) 48.9 (18.4)
(ml. kg- 1)
vl)Ozpeak 3.40 (0.45) 3.45 (0.41) 3.08 (0.33) 3.33 (0.29) 3.09 (0.37) 3.18 (0.37)
(m-s -1)
AC
[zO2peak 2.20 (0.62) 2.23 (0.66) 2.20 (0.55) 2.31 (0.48) a'b 2.22 (0.59) 2.05 (0.67)
1' rain- 1)
AC 1702 4 mmol.l- ~ 1.26 (0.32) 1.27 (0.26) 1.25 (0.19) 1.33
(0.32) a'b
1.28 (0.26) 1.29 (0.32)
(1. rain- 1)
a p < 0.05 pre vs post; up < 0.05 vs other intervention group
LU I05
Z
_0
I-- 100
Z
I.U
w
t-
z 95
e.e
e,i
kl.
o
N 90
TIME TRIAL
PERFORMANCE
I Run I
X
Train
|
El cont~o~ /
Fig. 4 Normalized time trial performance following intervention in
the enhanced running, cross-training and control groups. The time is
presented as a percentage (SE) of the pre-intervention score for that
group (I running, [] cross-training, [] control)
modest changes in the physiological responses during
running in the cross-training group that could explain
how cross-training enhanced running performance. As
expected the enhanced running group improved
v4 mmol' 1-1, supporting earlier suggestions we have
made regarding the mechanism of improvement in run-
ning performance in already trained runners (Daniels
et al. 1978). Non-active muscles are of established im-
portance relative to the uptake of lactate during exer-
cise (Stainsby and Brooks 1990). Lactate removal is
well established as a central factor in the control of
blood lactate accumulation during exercise (MacRae
et al. 1992; Mazzeo et al. 1986). However, there was
no change in v4 mm in the cross-training group that
would support the concept that a lactate "sink" in the
endurance trained upper extremity muscles contributed
to improved lactate metabolism during running. Hof-
fmann et al. (1993) have reported a dissociation be-
tween changes
in
gO2pea k and the ventilatory threshold
in response to either specific or non-specific training,
with the ventilatory threshold being less responsive to
non-specific training. Our results are also consistent
with findings of no change in the "local"RPE after
non-specific training despite increases
in
gO2pea k
(Lewis et al. 1980).
Medbo and Burgers (1990) have reported significant
increases in the Y, O2 deficit in response to high-inten-
sity training, although the precise nature of high-inten-
sity training did not seem to greatly influence the mag-
nitude of increase. Changes in YO2 deficit were, how-
ever, less in female subjects than in males. Given the
high percentage of female subjects in our sample and
the primarily moderate intensity of the training in this
study, large changes in the 5~O2 deficit were not to be
expected. Because our subjects were considerably less
than elite athletes and we wanted to be able to measure
steady-state 1/O2 over a reasonable range of running
velocities, we performed our treadmill runs with the
treadmill belt set at a slope of 5% compared to the
10-15% elevation recommended by Medbo et al.
(1988) and Olesen (1992). Olesen (1989, 1992) has sug-
gested that the measurement of the ~O2 deficit is very
dependent upon the testing and calculation procedures
used and has questioned the validity of the Y, O2 deficit
as a measure of anaerobic capacity. The longitudinal
nature of the present study should eliminate the magni-
tude of the treadmill slope as an issue since the slope
was equal both before and after intervention. We
372
(Foley et al. 1991) have demonstrated a comparatively
large day-to-day variability in the measurement of YO2
deficit which could contribute to the lack of systematic
change in this study. In any case, anaerobic capacity as
estimated by the FOg deficit did not seem to be a major
contributor to performance either before or after cha-
nges in training load.
An alternative explanation for the phenomena first
noted by single sport athletes training for triathlons is
that to compensate for a reduction in training volume
the athletes may have trained at a higher intensity.
Thus, higher-intensity single-sport training, rather than
a metabolic "crossover" effect, could be postulated at
the cause of the maintained single sport performance
capacity. Given the established importance of training
intensity to athletic performance (Foster 1983; Hickson
et al. 1985; Lehmann et al. 1992), there is a reasonable
rationale for such a suggestion. However, since the
increase in training load in the cross-training group
was achieved without a notable increase in training
intensity (Fig. 3), our data would not support this
suggestion. Even in the enhanced running group, in-
creases in training load seem mostly to be associated
with increases in training duration rather than train-
ing intensity. Certainly, the effects of independent
manipulation of the details of single-sport training
on subsequent performance is a high priority for future
studies.
In summary, the results of the present study indicate
that muscularly dissimilar exercise (swimming) contrib-
utes to improved running performance in individuals
training for running, although not to the same degree
as similar increases in muscularly specific training load.
Thus, muscularly dissimilar "cross-training" appears
to be useful relative to enhancing specific athletic
performance if the specific training load cannot be
increased to optimal levels. This effect is in addition to
the potential for athletes using non-specific training
during periods when ge.neral fitness is the primary
training goal.
Acknowledgement This study was supported by a research grant
from the Athlete Performance Division of the United States Olym-
pic Committee.
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... The CR10-point scale, adapted by Foster et al. [34] was applied thirty minutes after the end of each training session/match through an app on a tablet. All players rated their RPE which were then multiplied by the session durations to obtain the s-RPE [34,35]. The players were previously familiarized with the scale, and all answers were provided individually to avoid non-valid scores. ...
... Other study demonstrated that ACWR >2.0 was associated with higher risk of injury, while ACWR ≥1. 35 to ≤1.50 AU could be considered to prevent injury risk during the pre-and early periods of the in-season [42]. Meanwhile, ACWR-injury association did constitute the ability to detect injury occurrence [59] which was reinforced by recent studies [45][46][47][48][49][50][51]. ...
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Background: The aims of this study were to describe the variations of training monotony (TM), training strain (TS), and acute:chronic workload ratio (ACWR) through Hooper Index categories (fatigue, stress, DOMS, and sleep quality) and to compare those variations between player status and player positions. Methods: Seventeen male professional soccer players participated in this study. Considering player status, participants were divided in nine starters and eight non-starters. Additionally, participants were divided by playing positions: three wide defenders, four central defenders, three wide midfielders, four central midfielders, and three strikers. They were followed during 40-week in-season period. TM, TS, and ACWR were calculated for each HI category, respectively. Data were grouped in 10 mesocycles for further analysis. Results: Results showed variations across the mesocycles. In general, starters showed higher values for TM, TS, and ACWR calculations than non-starters, although there were some exceptions. Regarding player positions, significant differences were found in stress between wide defenders vs central midfielders for TM (p = 0.033, ES = 5.16), central defenders vs wide defenders for ACWR (p = 0.044, ES = 4.95), and in sleep between wide defenders and strikers for TM (p = 0.015, ES = 5.80). Conclusions: This study revealed that an analysis of players' well-being parameters according to player status and positions can provide clear information to the coaches and their staff to complement the tasks of training monitoring.
... Thirty minutes after the end of each training session, players rated their RPE value using an app on a tablet. The scores provided by the players were also multiplied by the training duration, to obtain the s-RPE 28,30 . The players were previously familiarized with the scale, and all the answers were provided individually to avoid non-valid scores. ...
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The purposes of this study were (a) to determine the variations in internal and external measures of training monotony (TM) and strain (TS) in professional soccer players according to periods of the season and playing positions, and (b) to analyze the relationships between internal and external measures of TM and TS. Twenty male professional players (age = 29.4 ± 4.4 years) were followed for 20 weeks through session rating of perceived exertion (s-RPE), total distance (TD), high-speed running distance (HSRD) and sprint distance (SpD). Regardless of measure, highest mean TM and TS scores were observed in mid-season and end-season. In general, wingers and strikers tended to have greater values in TM. Midfielders exhibited greater TS of TD and SpD. Correlation results for TM revealed that s-RPE was positively associated with SpD in early-season (r = 0.608) and negatively associated in mid-season (r = − 0.506). Regarding the TS, result demonstrated that s-RPE is negatively associated with HSRD in early-season (r = − 0.464) and positively associated in mid-season (r = 0.476). In general, there different meanings in correlations between internal and external measures across the season. On the one hand, our findings highlighted that TM and TS of professional soccer players is sensitive to period of the season and player’s position, but on other hand, correlation analyses proved that changes in one external/internal measure does not cause changes in another external/internal measure which support the constant monitoring of these values across the season.
... This method has been described as being valid for quantifying efforts during training and football matches [29][30][31] and has been proposed for use in the context of football and other team sports [32,33]. For example, Foster et al. [34][35][36] proposed the RPE to assess the "hardness" of the entire training session and to evaluate internal load in endurance and team-sport athletes. In addition, the RPE provides information in a simple, practical, and low-cost way [37]. ...
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This study aimed to determine the rated perceived exertion (RPE) and match load (RPE-ML) to compare pre-post-match vertical jump (VJ) capacity according to cerebral palsy (CP) players’ sport classes (i.e., FT1–FT3) and playing positions and to explore whether the neuromuscular performance variation is associated with the internal load of para-footballers with CP. Fifty-six male para-footballers performed two VJ tests before and immediately after a competitive CP football match, followed by measurements of the players’ RPE and RPE-ML. There were no significant differences (p > 0.05) in the pairwise comparisons for RPE and RPE-ML according to sport classes and playing position. A significant reduction in the VJ performance was found for each player sport class and playing position in squat jump (SJ) (p < 0.01; 0.24 < dg < 0.58) and countermovement jump (CMJ) (p < 0.05; 0.22 < dg < 0.45). Regarding the pairwise comparisons, players with the minimal impairment criteria (FT3) obtained higher deficit scores during SJ than those belonging to the FT1 and FT2 (p = 0.003; 1.00 < dg < 1.56). Defenders experienced the lowest performance compared to midfielders and attackers in SJ performance (p = 0.027; 0.94 < dg < 1.28). Significant correlations were obtained between ΔSJ or ΔCMJ and RPE or RPE-ML (r = −0.58 to −0.75; p < 0.001). These findings provide novel information supporting the notion that fatigue induced after a competitive match causes notable impairments in VJ performance differentiated according to sport class and playing position in para-footballers with CP.
... 3) RPE: The RPE of each athlete was recorded 30 min after each training session, using Foster's RPE scale (0-10) (Foster et al., 1995). 4) Running speed and distance: Each test was videotaped live using a professional digital camera (Sony NX100). ...
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This study aimed to investigate whether the heart rate variability index (TLHRV) during five ball-drills could be used to quantify training load (TL) in collegiate basketball players. Ten elite male college basketball athletes (18.2 ± 0.4 years) were recruited to perform five ball-drills (1V1, 2V2, 3V3, 4V4, and 5V5) which lasted 10 min and varied in intensity. During each drill, TLHRV, training impulse (TRIMP), rating of perceived exertion (RPE), speed, and distance were recorded by Firstbeat, Foster’s RPE scale, and SiMi Scout. The correlation (Spearman’s and Pearson’s correlation coefficient), reliability (intra-class correlation coefficient, ICC), and agreement (Bland-Altman plots) among TLHRV, TRIMP, RPE, speed, and distance were examined. TLHRV was significantly correlated with TRIMP (r = 0.34, p = 0.015) and RPE (r = 0.42, p = 0.002). TLHRV was significantly correlated with training intensity (r = 0.477, p = 0.006) but not with volume (r = 0.272, p = 0.056). TLHRV and TRIMP, RPE showed significant intraclass relationships (ICC = 0.592, p = 0.0003). Moreover, TLHRV differentiated basketball drills of equal volume and varying intensity. We concluded that TLHRVmay serve as an objective and rational measure to monitor TL in basketball players.
... To avoid non-valid values, all players were previously familiarized with the scale and all answers were provided on google forms, through a tablet. Then, each training/match session value was multiplied by the, respectively, session duration to produce the s-RPE [24,25]. ...
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Although data currently exists pertaining to the intensity in the women’s football match, the knowledge about training is still scarce. Therefore, the aim of this study was to quantify external (locomotor activity) and internal (psychophysiological) intensities, as well as the wellness profile of the typical microcycle from professional female soccer players during the 2019/20 in-season. Ten players (24.6 ± 2.3 years) from an elite Portuguese women soccer team participated in this study. All variables were collected in 87 training session and 15 matches for analysis from the 2019–2020 in-season. Global positioning variables such total distance, high-speed running, acceleration, deceleration and player load were recorded as intensity while Rated Perceived Exertion (RPE) and session-RPE were recorded as internal measures. The Hooper Index (HI) was collected as a wellness parameter. The results showed that internal and external intensity measures were greater in matches compared to trainings during the week (match day minus [MD-], MD-5, MD-4, MD-2), p < 0.05 with very large effect size (ES). In the same line, higher internal and external intensity values were found in the beginning of the week while the lowest values were found in MD-2 (p < 0.05, with very large ES). Regarding wellness, there was no significant differences in the HI parameters between the training days and match days (p > 0.05). This study confirmed the highest intensity values during MD and the lowest on the training session before the MD (MD-2). Moreover, higher training intensities were found in the beginning of the training week sessions which were then reduced when the MD came close. Wellness parameters showed no variation when compared to intensity measures. This study confirmed the hypothesis regarding internal and external intensity but not regarding wellness.
... Thirty minutes after each session, players individually provided their RPE value using a tablet to avoid non-valid scores. The RPE values provided were also multiplied by the training duration, to obtain the s-RPE [31,32]. Previously, all players were familiarized with RPE scale. ...
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Background The aim of this study was to describe and compare the in-season variations of acute: chronic workload ratio (ACWR) coupled, uncoupled, and exponentially weighted moving average (EWMA) through session rating of perceived exertion (s-RPE), total distance (TD), high-speed running distance (HSRD) and sprint distance (SPRINT) in three different periods of an elite soccer season according to player positions. Methods Twenty male elite players (age: 29.4 ± 4.4) from an Asian First League team were daily monitored for twenty consecutive weeks during the 2017–2018 in-season. Forty-seven trainings and twenty matches were monitored using global positioning system units (GPS) to collect TD, HSRD and SPRINT. Through the collection of s-RPE, TD, HSRD, and SPRINT by ACWR and EWMA were calculated for each training session. Results The results revealed that according to different periods of the season, workload measures observed in mid-season were meaningfully higher compared with early-season (g = ranging from 0.53 to 4.98) except for EWMA SPRINT . In general, wingers and strikers tended to have greater scores in workload measures compared to the defenders and midfielders (g = ranging from 0.41 to 5.42). Conclusions These findings may provide detailed information for coaches and sports scientists regarding the variations of acute and chronic workload ratio and external loading in-season and between player positions in an elite soccer team.
... Thirty minutes after each session, players individually provided their RPE value using a tablet to avoid non-valid scores. The RPE values provided were also multiplied by the training duration, to obtain the s-RPE [15,17]. Previously, all players were familiarized with the RPE scale. ...
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Simple Summary In this study, we analyse the relationship of the in-season variations of external, internal and well-being measures across different periods of a semi-professional soccer season (early-, mid- and end-season) and describe TM and TS for the entire period of the analysis. The main findings of our study revealed that increasing the training intensity affects the well-being of the players and consequently the training intensity management. Coaches and their staff should consider the results of this study, because despite the relationship between external and internal intensity, each has a unique effect on the perception of the player’s training intensity management. Abstract The purpose of this study was two-fold: (a) to describe and analyse the relationship of the in-season variations of external and internal intensity metrics as well as well-being measures across different periods of a semi-professional soccer season (early-, mid- and end-season); and (b) to describe training monotony (TM) and training strain (TS) for 20 weeks in a semi-professional soccer season. Eighteen semi-professional players (age: 29 ± 4.1) from the Asian First League team participated in this study. The players were monitored for 20 consecutive weeks during in-season for external training intensity, internal training intensity and well-being parameters. The in-season was organized into three periods: early-season (weeks 1–7); mid-season (weeks 8–13); and end-season (weeks 14–20). Total distance (TD), high-speed running distance (HSRD), sprint distance, rate of perceived exertion (RPE), session-RPE (s-RPE), TM, TS, heart rate average and maximum, as well as sleep quality, stress and muscle soreness were collected. Results revealed that TD, HSRD and sprint distance (total values) were meaningfully greater during end-season than in the early-season. RPE showed a significantly highest value during the end-season (4.27 AU) than in early- (3.68 AU) and mid-season (3.65 AU), p < 0.01. TS showed significant differences between early-season with mid-season (p = 0.011) and end-season (p < 0.01), and the highest value occurred in week 17 during end-season (6656.51 AU), while the lowest value occurred in week 4 during early-season (797.17 AU). The average TD periods showed a moderate to large correlation with RPE, sleep and s-RPE at early-, mid- and end-season. Increasing the training intensity without considering the well-being of the players affects the performance of the team. Examining processes of the relationship between training intensity and other psychological indicators among players will probably be effective in training planning. Sports coaches and fitness professionals should be wary of changes in TM and TS that affect players performance. Therefore, to better control the training, more consideration should be given by the coaches.
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The aim of this study was to compare the two methods, Bulgarian and small sided games (1 VS 1 ; 2 VS 2), in the development of the explosive strength of the lower limbs and the technical abilities of the two western teams Etihad and Wydad of Tissemssilt, The sample included male U17 football players, randomly selected, and divided into two experimental groups of (21) players each group. The first group, trained according to the Bulgarian method was characterized by: - Age: (15.61 ± 0.49 years), age of training: (3.28 ± 0.64 years), weight: (66.76 ± 3.79 Kg), height: (1.71 ± 0.04 cm), body mass index: (22.66 ± 0.81 BMI = P / T²). The second group trained according to the small sided games method was characterized by: - the Age: (15.57 ± 0.50 years), the Age of training: (3.38 ± 0.66 years), the weight: (66,90 ± 3,72 kg), the size: (1.72 ± 0.04 cm), body mass index: (22.36 ± 0.87 BMI = P / T²). In this research, the researcher adopted the experimental method by proposing two training programs, the first according to the Bulgarian method applied on the Etihad of tissemssilt, and the second according to the small sided games (1X1 2X2) applied on the Widad of tissemssilt in the period from 01/08/2016 to 21/09/2016 which means a monthly plan including 06 weeks with 11 training sessions in each program during the specific preparation phase, After the application of the prospective physical and technical tests from 22 to 26/09/2016 the researcher recorded statistically significant differences between all the prospective and retrospective tests in favor of the prospective tests which underline the effectiveness of the two training programs in the development of the upper limbs strength, contre mouvement jump (relaxation, power and muscle strength), in addition to technical skills (hitting the ball with head, feet for the longest distance possible), whereas in the prospective comparison between the two samples the researcher did not conclude to statistically significant differences in the physical tests contrary to what he recorded in the technical tests by the presence of statistically significant differences for hitting ball with head, feet for the longest distance possible in favor of the first sample, and the differences were also statistically significant in favor of the second sample for the tests of ball interception and juggling. In the end, the researcher came up with a set of recommendations, the most important is the need to use both methods in the preparation of young players, because of its advantages in the development of the physical and technical level, and the results of our tests are enough to confirm it. Keywords: Bulgarian method; Small sided games; Explosive force; Technical capacity.
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Training load (TL) is a widely used concept in training prescription and monitoring and is also recognized as as an important tool for avoiding athlete injury, illness, and overtraining. With the widespread adoption of wearable devices, TL metrics are used increasingly by researchers and practitioners worldwide. Conceptually, TL was proposed as a means to quantify a dose of training and used to predict its resulting training effect. However, TL has never been validated as a measure of training dose, and there is a risk that fundamental problems related to its calculation are preventing advances in training prescription and monitoring. Specifically, we highlight recent studies from our research groups where we compare the acute performance decrement measured following a session with its TL metrics. These studies suggest that most TL metrics are not consistent with their notional training dose and that the exercise duration confounds their calculation. These studies also show that total work done is not an appropriate way to compare training interventions that differ in duration and intensity. We encourage scientists and practitioners to critically evaluate the validity of current TL metrics and suggest that new TL metrics need to be developed.
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To determine whether the reduced blood lactate concentrations [La] during submaximal exercise in humans after endurance training result from a decreased rate of lactate appearance (Ra) or an increased rate of lactate metabolic clearance (MCR), interrelationships among blood [La], lactate Ra, and lactate MCR were investigated in eight untrained men during progressive exercise before and after a 9-wk endurance training program. Radioisotope dilution measurements of L-[U-14C]lactate revealed that the slower rise in blood [La] with increasing O2 uptake (VO2) after training was due to a reduced lactate Ra at the lower work rates [VO2 less than 2.27 l/min, less than 60% maximum VO2 (VO2max); P less than 0.01]. At power outputs closer to maximum, peak lactate Ra values before (215 +/- 28 mumol.min-1.kg-1) and after training (244 +/- 12 mumol.min-1.kg-1) became similar. In contrast, submaximal (less than 75% VO2max) and peak lactate MCR values were higher after than before training (40 +/- 3 vs. 31 +/- 4 ml.min-1.kg-1, P less than 0.05). Thus the lower blood [La] values during exercise after training in this study were caused by a diminished lactate Ra at low absolute and relative work rates and an elevated MCR at higher absolute and all relative work rates during exercise.
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The influence of an increase in training volume (ITV; February 1989) vs intensity (ITI; February 1990) on performance, catecholamines, energy metabolism and serum lipids was examined in two studies on eight, and nine experienced middle- or long-distance runners; seven participated in both studies. During ITV, mean training volume was doubled from 85.9 km.week-1 (pretrial phase) to 174.6 km within 3 weeks. Some 96%-98% of the training was performed at 67 (SD 8)% of maximal performance. During ITI, speed-endurance, high-speed and interval runs increased within 3 weeks from 9 km.week-1 (pretrial phase) to 22.7 km.week-1 and the total training distance from 61.6 to 84.7 km.week-1. The ITV resulted in stagnation of running velocity at 4 mmol lactate concentration and a decrease in total running distance in the increment test. Heart rate, energy metabolic parameters, nocturnal urinary catecholamine excretion, low density, very low density lipoprotein-cholesterol and triglyceride concentrations decreased significantly; the exercise-related catecholamine plasma concentrations increased at an identical exercise intensity. The ITI produced an improvement in running velocity at 4 mmol lactate concentration and in total running distance in the increment test; heart rate, energy metabolic parameters, nocturnal catecholamine excretion, and serum lipids remained nearly constant, and the exercise-related plasma catecholamine concentrations decreased at an identical exercise intensity. The ITV-related changes in metabolism and catecholamines may have indicated an exhaustion syndrome in the majority of the athletes examined but this hypothesis has to be proven by future experimental studies.