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Rønnestad, B. R., Hansen, E. A., Raastad, T. (2010). In-season strength
maintenance training increases well-trained cyclists' performance.
European Journal of Applied Physiology, 110, 1269-1282.
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www.springerlink.com: http://dx.doi.org/10.1007/s00421-010-1622-4
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1
In-season strength maintenance training increases well-
trained cyclists’ performance
Running head: “Strength maintenance training in cyclists”
Bent R. Rønnestad1, Ernst Albin Hansen2, and Truls Raastad2
1Lillehammer University College, Lillehammer, Norway
2Norwegian School of Sport Sciences, Oslo, Norway
Corresponding author:
Bent R. Rønnestad
Lillehammer University College
PB. 952, 2604 Lillehammer
Norway
E-mail: bent.ronnestad@hil.no Phone: +47 61288193 Fax: +47 61288200
2
Abstract
We investigated the effects of strength maintenance training on thigh muscle cross-sectional
area (CSA), leg strength, determinants of cycling performance, and cycling performance.
Well-trained cyclists completed either 1) usual endurance training supplemented with heavy
strength training twice a week during a 12-week preparatory period followed by strength
maintenance training once a week during the first 13 weeks of a competition period (E+S;
n=6 [♂=6]), or 2) usual endurance training during the whole intervention period (E; n=6
[♂=5, ♀=1]). Following the preparatory period, E+S increased thigh muscle CSA and 1RM
(p<0.05), while no changes were observed in E. Both groups increased maximal oxygen
consumption and mean power output in the 40-min all-out trial (p<0.05). At thirteen weeks
into the competition period, E+S had preserved the increase in CSA and strength from the
preparatory period. From the beginning of the preparatory period to 13 weeks into the
competition period, E+S increased peak power output in the Wingate test, power output at 2
mmol·l-1 [la-], maximal aerobic power output (Wmax), and mean power output in the 40-min
all-out trial (p<0.05). The relative improvements in the last two measurements were larger
than in E (p<0.05). For E, Wmax and power output at 2 mmol·l-1 [la-] remained unchanged. In
conclusion, in well-trained cyclists, strength maintenance training in a competition period
preserved increases in thigh muscle CSA and leg strength attained in a preceding preparatory
period, and further improved cycling performance determinants and performance.
Key words: AEROBIC POWER OUTPUT, PEAK POWER OUTPUT, CONCURRENT
TRAINING, WEIGHT TRAINING, ENDURANCE PERFORMANCE
3
INTRODUCTION
Incorporation of strength training into cyclists’ preparatory period has received some attention
during the last two decades (Bastiaans et al. 2001; Bishop et al. 1999; Hausswirth et al. 2010;
Hickson et al. 1988; Rønnestad et al. 2009; 2010). However, the effect of strength training on
endurance cycling performance and traditional indicators of cycling performance like lactate
threshold, maximum aerobic power output (Wmax), and cycling economy, is still somewhat
unclear. Importantly, adding strength training to usual endurance training does not appear to
negatively affect maximal oxygen consumption (VO2max) in cyclists (Bishop et al. 1999;
Hausswirth et al. 2010; Rønnestad et al. 2010). Strength training has been shown to improve
lactate threshold in untrained individuals (Marcinik et al. 1991). However, studies of trained
cyclists have reported both no change in lactate threshold (Bishop et al. 1999; Hausswirth et
al. 2010) and increased power output at a blood lactate concentration ([la-]) of 2 mmol·l-1 after
a period of concurrent strength and endurance training (Rønnestad et al. 2010). Improvement
in cycling economy after a period of strength training has been observed for untrained
individuals (Loveless et al. 2005) and trained cyclists (Sunde et al. 2009), but not well-trained
cyclists (Aagaard et al. 2007; Rønnestad et al. 2010). We have recently reported that strength
training can improve performance during all-out cycling performed immediately following
prolonged submaximal cycling, which simulates, for example, the final kilometers of a road
race (Rønnestad et al. 2009). The intervention in the majority of the above cited studies lasted
for ~10-12 weeks and was conducted during the preparatory period. To preserve strength
gained during the preparatory period, we know that cyclists must perform some sort of
strength maintenance training during the competition period, but how this maintenance
training should be performed and how it will affect performance is not clear. Interestingly,
maintenance of strength gained in the preparatory period may give some additional
performance enhancing effects in the competition period because all other determinants of
4
cycling performance are optimal in this period, and because the cyclists have had the time to
adjust to their new level of strength. However, whether strength maintained in the competition
period really results in enhanced performance remains to be demonstrated. Thus, the effect of
strength maintenance training during the competition period on cycling performance and
performance determinants in well-trained cyclists should be investigated.
Performance in road cycling races depends on a number of factors in addition to those
mentioned above. One of these additional factors is the ability to generate high power output
over a short period of cycling. This ability is essential for a cyclist who needs to close a gap,
break away from the pack, or perform well in a sprint. The Wmax as well as the mean and peak
power output in a Wingate test reflect the ability to generate high power output over a short
period of time. Peak power output in the Wingate test has been reported to be increased after a
period of strength training in both non-cyclists (Beck et al. 2007) and cyclists (Bastiaans et al.
2001; Rønnestad et al. 2010). These findings are supposedly explained by the facts that peak
power output in cycling is affected by leg muscle cross-sectional area (CSA) and that strength
training increases this CSA (Izquierdo et al. 2004). However, it has been reported that only a
small part (0%-45%) of the strength gained during a previous strength training period is
preserved after 8-12 weeks without strength training (Andersen et al. 2005; Graves et al.
1988; Narici et al. 1989). Such a period without strength training is accompanied by reduction
in muscle fiber and muscle CSA (Andersen et al. 2005; Narici et al. 1989) as well as reduced
peak power output during a Wingate test (Kraemer et al. 2002). To mitigate such detraining
effects, inclusion of strength maintenance programs that require high intensity muscle actions
but low training volume and frequency has been recommended (Graves et al. 1988; Mujika
and Padilla 2000). It has been reported that it is possible to maintain previously gained
strength with one high-intensity strength training session per week in recreationally strength-
5
trained subjects (Graves et al. 1988). However, it has also been observed that adding large
volumes of endurance training to strength training may inhibit adaptations to strength training
(Kraemer et al. 1995). Therefore, whether it is possible to maintain an initial gain in strength
and related variables during a subsequent period of high volume of concurrent endurance
training in cyclists is unclear and should be investigated.
The primary aim of the present study was to investigate the hypothesis that a strength
maintenance training program consisting of one weekly session conducted during the first 13
weeks of the competition period would positively affect long-term endurance performance
(mean power output in a 40-min all-out trial) at the end of that period. As a part of this,
determinants of long-term endurance cycling performance, including cycling economy and
power output at 2 mmol·l-1 [la-] were measured. In addition, vigorous aspects of a road cycling
race, including power output in a Wingate test and Wmax should also be positively affected by
the strength maintenance training. As a prerequisite for the hypothesized effects on in-season
performance, strength maintenance training must be capable of preserving the previous
increases in thigh muscle CSA and strength (1RM in half squat). Consequently, this was
controlled for in the present study.
METHODS
Participants
Twelve well-trained cyclists competing at a national level volunteered for the study, which
was approved by the Southern Norway regional division of the National Committees for
Research Ethics. The cyclists were classified as well-trained based on the criteria suggested
by Jeukendrup et al. (2000). All cyclists signed an informed consent form prior to
participation. None of the cyclists had performed any strength training during the preceding
6
six months. The intervention started at the same time as the start of the preparatory period.
The pre-tests were thus preceded by a transition period of ~ 3-4 weeks with low endurance
training volume.
Experimental design
Tests were conducted at three time points: 1) the beginning of a 12-week preparatory period
(pre-intervention) that preceded the competition period, 2) the end of the preparatory
period/beginning of the competition period (12 weeks), and 3) 13 weeks into the competition
period (25 weeks). The cyclists were divided into two groups. The cyclists in the experimental
group (E+S; n=6 [♂=6], age 29±3 years, height 185±3 cm) performed heavy strength training
in addition to usual endurance training. The cyclists in the control group (E; n=6 [♂=5, ♀=1],
age 31±3 years, height 181±4 cm) simply continued their usual endurance training.
Training
Endurance training consisted primarily of cycling, but some cross-country skiing was also
performed during the preparatory period (up to 10% of total training duration). Training
duration and intensity were calculated based on recordings from heart rate (HR) monitors
(Polar, Kempele, Finland). Endurance training was divided into three HR zones: 1) 60%-72%,
2) 73%-87%, and 3) 88%-100% of maximal HR. The weekly duration of the endurance
training and the distribution of this training within the three intensity zones were similar
between groups in the preparatory period (E+S: 7.4±1.5 hrs, 3.3±1.1 hrs, and 0.4±0.1 hrs,
respectively and E: 7.2±1.6 hrs, 3.8±1.0 hrs, and 0.7±0.3 hrs, respectively) and in the
competition period (E+S: 6.3±1.7 hrs, 4.7±1.7 hrs, and 0.6±0.2 hrs, respectively and E:
7.3±1.7 hrs, 4.3±0.8 hrs, and 0.8±0.4 hrs, respectively). No significant difference between
E+S and E was found when comparing total training duration (which included competitions,
7
strength training, core stability training and stretching) in the preparatory period (165 ± 17 hrs
and 149 ± 12 hrs, respectively, p=0.44) or in the competition period (175 ± 9 hrs and 179 ± 29
hrs, respectively, p=0.88). The cyclists in E+S and E participated in the same number of
competitions during the competition period (11 ± 2 and 10 ± 1, respectively).
The heavy strength training that was performed by the cyclists in E+S targeted leg muscles
and was planned to be performed twice per week during the preparatory period and once per
week during the competition period. Adherence to the strength training was high, with E+S
cyclists completing 97±1% of the planned strength training sessions during the preparatory
period and 86±4% of the planned strength training sessions during the competition period.
The strength training regimen was designed to improve cycling performance by using as
cycling-specific exercises as possible. Since peak force during pedalling occurs at
approximately a 100° knee angle (Coyle et al. 1991), strength training exercises were
performed with a knee angle between 90° and almost full extension. Thus, the strength
training exercises focused on the muscles involved in the primarily power generating phase
(the downstroke: e.g. m. gluteus maximus, the quadriceps, and the triceps surae), but also
muscles involved in the transition phase at the bottom dead center (e.g. m. gastrocnemius) and
in the upstroke (e.g. m. rectus femoris and m. iliopsoas) were trained during the strength
exercises (Hug & Dorel 2009). In addition, since cyclists work each leg alternately when
cycling, and it has been observed a force deficit during bilateral leg exercises (Cresswell and
Ovendal 2002; Schantz et al. 1989), one-legged exercises were chosen where practical. Based
on the assumption that it is the intended rather than actual velocity that determines the
velocity-specific training response (Behm and Sale 1993), the heavy strength training was
conducted with focus on maximal mobilization in the concentric phase (lasting around 1 s),
8
while the eccentric and non-cycling specific phase was performed more slowly (lasting
around 2-3 s).
At the start of each strength training session, cyclists performed a ~10-min warm-up at self-
selected intensity on a cycle ergometer, followed by 2-3 warm-up sets of half squat with
gradually increasing load. The performed exercises were: half squat, recumbent leg press with
one leg at a time, standing one-legged hip flexion, and ankle plantar flexion (Figure 1). All
cyclists were supervised by an investigator at all workouts during the first two weeks and
thereafter at least once every second week throughout the intervention period. During the first
three weeks, cyclists trained with 10RM sets at the first weekly session and 6RM sets at the
second weekly session. During the following three weeks, sets were adjusted to 8RM and
5RM, respectively. During the final six weeks of the preparatory period, sets were adjusted to
6RM and 4RM, respectively (Table 1). The cyclists were encouraged to increase their RM
loads continually throughout the intervention period and they were allowed assistance on the
last repetition. The number of sets in each exercise was always three during the preparatory
period. During the competition period, the order of the strength training exercises was the
same, but the number of sets was reduced to two in half squat and leg press. These two
exercises were performed with five repetitions at a load corresponding to 80-85% of 1RM.
Hip flexion and ankle plantar flexion were performed with only one set and a load
corresponding to 6RM (Table 1). During the competition period, strength training exercises
were performed with maximal effort in the concentric phase and 2 min rest period between
each set and exercise.
(Insert Figure 1 about here)
(Insert Table 1 about here)
9
Testing
Testing was completed as follows: day 1) measurement of thigh muscle CSA, day 2) maximal
strength tests, day 3) incremental cycle tests for determination of blood lactate profile and
VO2max, and day 4) 30-s Wingate test and 40-min all-out trial. This test order was repeated at
all test occasions. The cyclists were instructed to refrain from intense exercise the day
preceding testing, to prepare for the trial as they would have done for a competition, and to
consume the same type of meal before each test. They were not allowed to eat during the hour
preceding a test or trial or to consume coffee or other products containing caffeine during the
preceding three hours. The cyclists were cooled with a fan during cycling. All cycling was
performed under similar environmental conditions (20-22˚C). Testing at pre-intervention, 12
weeks, and 25 weeks was conducted at the same time of day to avoid influence of circadian
rhythm. All cycling was performed on the same electromagnetically braked cycle ergometer
(Lode Excalibur Sport, Lode B. V., Groningen, The Netherlands), which was adjusted
according to each cyclist’s preference for seat height, horizontal distance between tip of seat
and bottom bracket, and handlebar position. Cyclists were allowed to choose their preferred
cadence during all cycling and they used their own shoes and pedals.
Thigh muscle cross-sectional area measurement
Magnetic resonance tomography (MR) (Magnetom Avanto 1.5 Tesla, Siemens AG, Munich,
Germany) was used to measure thigh muscle CSA. Participants were scanned in supine
position. The feet were fixed and elevated by a pad placed at the back of the knees to prevent
the muscles on the back of the thighs from compressing against the bench. The machine was
centred 2/3 distally on the femur and nine cross-sectional images were sampled starting at the
10
proximal edge of the patella and moving towards the iliac crest, with 35 mm interslice gaps.
Each image represented a 5 mm thick slice. The images were subsequently uploaded to a
computer for further analysis. The images of the thigh muscles were divided into knee
extensor and knee flexor/adductor compartments using a tracer function in the software. The
CSA of the thigh muscles was measured from the three most proximal images and the average
CSA of these three images was used for statistical analysis. Thirty images were reanalysed for
CSA by the same investigator. Mean CSA was found not to be different in the two analyses
and the CV of the differences between first and second measurement was 1.6%.
Strength test
Maximal strength of the leg extensors was measured as 1RM in half squat performed in a
Smith-machine. Prior to the pre-intervention test, two familiarization sessions were conducted
with the purpose of instructing the cyclists in proper half squat technique and testing
procedure. Strength tests were always preceded by a 10-min warm-up on a cycle ergometer.
Following warm-up, the cyclists performed a standardized protocol consisting of 3 sets with
gradually increasing load (40%, 75%, and 85% of predicted 1RM) and decreasing number of
repetitions (10, 7, and 3). The depth of the half squat was set to a knee angle of 90°. To ensure
similar knee angles during all tests, the cyclist’s squat depth was carefully monitored and
marked on a scale on the Smith-machine. Thus, each cyclist had to reach his or her individual
depth marked on the scale for the lift to be accepted. Similarly, the placement of the feet was
monitored for each cyclist to ensure identical test positions during all tests. The first 1RM
attempt was performed with a load approximately 5% below the predicted 1RM load. After
each successful attempt, the load was increased by 2%-5% until the cyclist failed to lift the
same load after 2-3 consecutive attempts. Subjects rested for 3 min between each attempt. All
strength tests throughout the study were conducted using the same equipment with identical
11
positioning of the cyclist relative to the equipment and monitored by the same experienced
investigator. The strength test at 25 weeks was conducted 3-5 days after the last strength
training session. The coefficient of variation for test–retest reliability for this test has been
found to be 2.9% (Rønnestad 2009).
Blood lactate profile test
A blood lactate profile was determined for each cyclist by plotting [la-] vs. power output
performed during the submaximal continuous incremental cycling. The test started without
warm-up, with 5 min cycling at 125 W. Cycling continued and power output was increased by
50 W every 5 min. Blood samples were taken from a finger tip while the cyclists were seated
on the cycle ergometer at the end of each 5-min bout and were analyzed for whole blood [la-]
using a portable lactate analyzer (Lactate Pro LT-1710, Arcray Inc. Kyoto, Japan). The test
was terminated when a [la-] of 4 mmol·l-1 or higher was measured. The female cyclist in E
achieved 4 mmol·l-1 [la-] before the 225 W bout and her data is therefore not included in the
figure presenting the results from the continuous incremental test. However, including her
data in the bouts she did complete did not change the statistical outcome. VO2, respiratory
exchange ratio (RER), and HR were measured during the last 3 min of each bout, and mean
values were used for statistical analysis. HR was measured using a Polar S610i heart rate
monitor (Polar, Kempele, Finland). VO2 was measured (30 s sampling time) using a
computerized metabolic system with mixing chamber (Oxycon Pro, Erich Jaeger, Hoechberg,
Germany). The gas analyzers were calibrated with certified calibration gases of known
concentrations before every test. The flow turbine (Triple V, Erich Jaeger, Hoechberg,
Germany) was calibrated before every test with a 3 l, 5530 series, calibration syringe (Hans
Rudolph, Kansas City, USA). Rate of energy expenditure was calculated from gross VO2
12
values and their matching RER values using the same method as Coyle et al. (1992). Rate of
perceived exertion (RPE) was recorded 4 min and 50 s into each bout, using Borg’s 6-20 scale
(Borg 1982). From this continuous incremental cycling test, the power output at 2 mmol·l-1
[la-] was calculated for each cyclist. The power output was calculated from the relationship
between [la-] and power output using linear regression between data points.
VO2max test
After termination of the blood lactate profile test, the cyclists rested for 3 h before completing
another incremental cycling test for determination of VO2max. This test has been described
elsewhere (Rønnestad et al. 2009). Briefly, the cyclists completed a 10-min warm-up followed
by a 1-min rest. The test was then initiated with 1 min of cycling at a power output
corresponding to 3 W·kg–1 (rounded down to the nearest 50 W). Power output was
subsequently increased by 25 W every minute until exhaustion. When the cyclists predicted
that they would not be able to complete another 25 W increase in power output, they were
encouraged to simply continue cycling at the current power output for as long as possible
(usually 30 to 60 s). VO2max (along with the complementary data) was calculated as the
average of the two highest VO2 measurements. Wmax was calculated as the mean power output
during the last 2 min of the incremental test.
Wingate test
The 30-s Wingate test was also performed on the Lode cycle ergometer. Braking resistance
was set to 0.8 Nm·kg-1 body mass. The Wingate protocol was managed from a personal
computer (running the Lode Wingate software, version 1.0.14) that was connected to the
cycle ergometer. After a 10-min warm-up and a 1-min rest, cyclists started cycling at ~ 60
rpm without braking resistance. Then, following a 3-s countdown, the braking resistance was
13
applied to the flywheel and remained constant throughout the 30-s all-out test. The cadence
was sampled at 5 Hz by a computer and matching power output values were calculated by the
software. The Lode Wingate software presented peak power output as the highest power
output achieved at any time during the 30-s all-out test. Mean power output was presented as
the average power output sustained throughout the 30 s, while minimal power was presented
as the lowest power output achieved during the 30 s. Peak and minimal power output were
used to calculate the fatigue index, defined here as the decline in power output per second
from peak power output to minimal power output. Cyclists remained seated throughout the
test and strong verbal encouragement was provided from the test personnel during the test. To
attain the highest possible peak power, subjects were instructed to pedal as fast as possible
from the start and not to preserve energy for the last part of the test. Cyclists then recovered
by cycling at ~100 W for 10 min before starting the 40-min all-out trial.
40 min all-out trial
In this 40-min trial the cyclists were instructed to cycle at as high an average power output as
possible. This type of test with a closed end has been shown to have a low coefficient of
variation (CV<3.5 %; Jeukendrup et al. 1996). Performance was measured as the average
power output during the trial. The cyclists were allowed to adjust the power output throughout
the trial using an external control unit mounted on the handlebar. The cyclists received no
feedback about HR and cadence, but they were aware of remaining time and instantaneous
power output. The cyclists were allowed to occasionally stand in the pedals during the trial
and to drink water ad libitum.
Statistics
14
All data in the text, figures, and tables are presented as mean±SE. To test for differences
between groups at pre-intervention, unpaired Student’s t-tests were used. In the 40-min all-out
trial there was a statistical power of 80% to detect a difference between the groups of 25 W with a
significance level (alpha) of 0.05 (two-tailed). This difference between groups is recognised as a
significant performance enhancement. For each group, measurements at pre-intervention, at 12
weeks, and 25 weeks were compared using one-way repeated measures ANOVA. If the
ANOVA reached significance, a Tukey’s HSD test was performed for post hoc analysis. To
test for differences between groups in relative changes, two-way repeated measures ANOVA
(time of intervention and group as factors) with Bonferroni post hoc tests were performed to
evaluate differences. In addition, two-way repeated measures ANOVA (time of intervention
and group as factors) with Bonferroni post hoc tests were performed for evaluation of
differences between groups in absolute values. ANOVA analyses were performed in
GraphPad Prism 5 (GraphPad Software Inc., CA, USA). Student’s t-tests were performed in
Excel 2003 (Microsoft Corporation, Redmond, WA, USA). All analyses resulting in p≤0.05
were considered statistically significant.
RESULTS
Comparison of groups at pre-intervention
There were no significant differences between E+S and E at pre-intervention with respect to
body mass, thigh muscle CSA (Figure 2), 1RM in half squat (Figure 3), VO2max (Table 2), or
measurements in any of the cycling performance tests except body mass-adjusted peak power
output during the Wingate test (Table 3).
Body mass, thigh muscle cross-sectional area, and strength
15
Body mass was unchanged from pre-intervention to 25 weeks in both E+S and E (pre-
intervention values were 79.7±4.4 kg and 73.7±4.2 kg, respectively). Thigh muscle CSA (sum
of flexors and extensors) increased by 4.4±0.6% in E+S during the preparatory period
(p<0.01), while no changes occurred in E from pre-intervention to 25 weeks. The relative
change in thigh muscle CSA during the preparatory period was greater in E+S than in E
(p<0.01). Furthermore, this larger thigh muscle CSA was preserved at 25 weeks (p<0.05,
Figure 2). Strength measured as 1RM in half squat increased by 23±3% in E+S during the
preparatory period (p<0.01) and this strength was preserved at 25 weeks. Strength remained
unchanged in E from pre-intervention to 25 weeks (Figure 3). Thus, the change in 1RM half
squat during the preparatory period and from pre-intervention to 25 weeks was larger in E+S
than in E (p<0.01).
(Insert Figure 2 about here)
(Insert Figure 3 about here)
VO2max and Wmax
Body mass-adjusted VO2max increased by 6±2% in E+S and 8±2% in E during the preparatory
period (p<0.05, Table 2). E+S achieved a further significant improvement from 12 weeks to
25 weeks (7±2%, p<0.05, Table 2), although there was no difference between groups. Wmax in
E+S increased by 8±1% from pre-intervention to 25 weeks (p<0.05), while no change
occurred in E (Table 2). The relative change in Wmax was larger in E+S than in E (p<0.05).
There were no differences between the groups in blood lactate concentrations obtained after
the VO2max test at any test occasion (Table 2).
(Insert Table 2 about here)
16
Blood lactate profile
Power output at 2 mmol·l-1 [la-] did not change for either group during the preparatory period.
However, E+S increased power output at 2 mmol·l-1 [la-] from 253±16 W at pre-intervention
to 284±13 W at 25 weeks (p<0.05), while no change was observed in E (pre-intervention
value of 248±26 W). There was, however, no statistically significant difference between
groups in relative change in power output at 2 mmol·l-1 [la-]. Lactate concentration at 275 W
was lower for both E+S and E at 12 weeks than at pre-intervention (p<0.05, Figure 4). The
relative decrease in [la-] at 25 weeks was larger in E+S than in E (p<0.05). ANOVA analysis
showed that during the blood lactate profile test, cycling economy, determined as body mass-
adjusted oxygen consumption at a given power output, remained unchanged during the
intervention period (pre-intervention to 25 weeks) for E+S. In contrast, cycling economy was
impaired (i.e., VO2 increased) for cyclists in E at the three highest power outputs (175 W, 225
W, and 275 W) (p<0.05, Figure 4). Only E+S reduced RPE at 225 W and 275 W at 25 weeks
(p<0.05, Figure 4). Both groups had decreased HR at all four power outputs from pre-
intervention to 25 weeks (p<0.05, Figure 4). RER at 275 W was reduced during the
preparatory period in both groups (p<0.05). E+S also had a reduced RER from pre-
intervention to 25 weeks at all power outputs (p<0.05, Figure 4). A comparison between E+S
and E of the relative changes from pre-intervention to 25 weeks showed no significant
difference between groups in VO2, RER, HR or RPE during the blood lactate profile test.
Furthermore, there was no change in gross efficiency during the intervention period in any of
the groups. The gross efficiency at a power output of 125 W, 175 W, 225 W, and 275 W was
18.6±0.4%, 20.0±0.2%, 20.8±0.1%, and 21.0±0.1%, respectively, as mean values across
groups, time points in the tests, and time points of intervention.
17
(Insert Figure 4 about here)
Power output in the 40-min all-out trial
Mean power output during the 40-min all-out trial increased during the preparatory period in
both E+S and E (8±2% and 4±1%, respectively; p<0.05, Figure 5), with no difference
between groups in relative increase. The increase in mean power output in the 40-min all-out
trial from pre-intervention to 25 weeks was larger in E+S than in E (14±3% vs. 4±1%,
respectively; p<0.05, Figure 5).
(Insert Figure 5 about here)
Power output in the Wingate test
Peak power output in the 30-s Wingate test increased in E+S from pre-intervention to 25
weeks, in both absolute values and when these were calculated relative to body mass (6±2%
and 8±2%, respectively, p<0.05, Table 3). No changes occurred in E. Neither of the groups
had significant changes in mean power output in the 30-s Wingate test (Table 3). The relative
change in fatigue index was larger in E+S than in E at the end of the preparatory period
(p<0.05, Table 3), resulting in a significant difference between groups at this point (p<0.05,
Table 3). However, fatigue index did not change for either group from pre-intervention to 25
weeks and there was no difference between groups at 25 weeks.
(Insert Table 3 about here)
Freely chosen cadence
18
Freely chosen cadence was unchanged from pre-intervention to 25 weeks in both groups. The
freely chosen cadence during the lactate profile test, VO2max test, and 40-min all-out trial was
87±2 rpm, 95±2 rpm, and 92±2 rpm, respectively, as mean values across groups, points of
time in the tests, and points of time in the intervention.
DISCUSSION
A novel finding of the present study was that strength maintenance training performed once a
week during a 13-week competition period preserved leg strength and thigh muscle CSA
increases achieved by well-trained cyclists during a preceding 12-week preparatory period. Of
practical importance, these in-season adaptations to strength maintenance training were
accompanied by superior adaptations in performance, measured as changes in 1) average
power output in a 40-min all-out trial, 2) [la-] at a power output of 275 W, and 3) Wmax.
Strength, thigh muscle CSA, and power output in Wingate test
As expected, two sessions per week of strength training increased leg strength and thigh
muscle CSA in E+S during the preparatory period. No changes in these measurements
occurred in E. It has been reported previously that if strength training is not maintained after a
strength training period, only a part (0%-45%) of the strength gained is retained after 8-12
weeks (Andersen et al. 2005; Graves et al. 1988; Narici et al. 1989). The loss of strength after
cessation of strength training is related to a reduction in muscle fiber CSA and muscle CSA.
These changes have also been shown to reduce peak power output in the Wingate test
(Andersen et al. 2005; Kraemer et al. 2002; Narici et al. 1989). Thus, to face the challenge of
counteracting in-season detraining effects, it has been suggested that during the competition
19
period athletes should complete strength maintenance programs that include high intensity
muscle actions and low weekly training volume and frequency (Graves et al. 1988; Mujika
and Padilla 2000). One challenge is that large volumes of endurance exercise may inhibit
adaptations to strength training (Kraemer et al. 1995). This may be interpreted as a need to
further increment volume and/or intensity in the in-season strength maintenance training
program since this is performed simultaneously with a large volume of endurance training. To
our knowledge the present study is the first to demonstrate that competitive cyclists can
maintain the initial strength and muscle CSA increases attained in a preceding preparatory
period with just a single heavy strength training session per week during a 13-week
competition period.
Peak power output often occurs during the first 5 s of an all-out Wingate test. Thus, peak
power output is mainly dependent on the size of the involved muscle mass and maximal leg
strength (Izquierdo et al. 2004). Therefore, the finding that E+S increased peak power output
during the intervention period may be explained by the increase in thigh muscle CSA and leg
strength. Correspondingly, the finding of no change in peak power output in E is probably
explained by no changes in thigh muscle CSA or leg strength. This finding has practical
implications, since the ability to generate high power output during a short period of time is
an important aspect of overall cycling performance (Atkinson et al. 2003).
VO2max, Wmax, and blood lactate profile
The finding of increased VO2max in both groups of cyclists from pre-intervention to 25 weeks
agrees with previous findings in cyclists (Sassi et al. 2008; White et al. 1982). This finding
was expected since the pre-intervention tests were conducted ~1 month after the end of the
competition season, a period of the year when endurance training volume is typically low.
20
Importantly, the added strength training did not impair the development of VO2max during
either the preparatory period or the first 13 weeks of the competition period. In fact, only E+S
achieved a statistically significant increase in VO2max from 12 to 25 weeks, though there was
no difference between groups. The observed increase in VO2max during the competition period
in E+S may be related to a smaller (but not significantly different from E) increase in VO2max
during the preparatory period. A closer examination of the endurance training reveals that
E+S had a larger, though not statistically significant, increase in the weekly amount of
endurance training in intensity zones 2 and 3 (73-100% of maximum HR) from the
preparatory period to the competition period (from 3.7±1.1 to 5.3±1.8 hrs for E+S, from
4.6±1.2 to 5.1±1.2 hrs for E). This change in the endurance training intensity may also affect
the adaptations in VO2max. The finding of no degradation of VO2max adaptations agrees with
other studies that have found no impairment of VO2max development for either trained or
untrained individuals performing concurrent endurance and strength training (McCarthy et al.
1995; Østerås et al. 2002).
There is no major difference between well-trained cyclists and elite cyclists in VO2max (Lucia
et al. 1998). Even though VO2max and Wmax are related, it seems that Wmax is the key indicator
separating elite cyclists from well-trained cyclists (Lucia et al. 1998). It is therefore
interesting to note that although both groups increased VO2max, only E+S increased Wmax from
pre-intervention to 25 weeks, with the relative increase being larger for E+S than E. Wmax is
influenced not only by VO2max and cycling economy, but also by anaerobic capacity (Jones
and Carter 2000). Therefore, the findings of larger increase in peak power output during the
Wingate test, 1RM, and thigh muscle CSA in E+S compared with E, in addition to a slightly
impaired cycling economy in E and no change in cycling economy in E+S, are all likely
contributors to the larger gain in Wmax in E+S. Power output determines velocity during
21
cycling and thus greatly affects performance. While our results concur with results from a
strength training study on untrained persons (Loveless et al. 2005), they contradict a study in
which trained cyclists replaced a portion of their endurance training with explosive strength
training (Bastiaans et al. 2001). The reason for such divergent findings remains unclear, but
can be due to differences in strength training programs, compliance, or circumstances related
to testing protocols.
Both groups reduced their HR at all power outputs from 125 W to 275 W after 25 weeks. The
finding of reduced HR at submaximal power outputs from the preparatory period into the
competition period is in line with other findings in trained cyclists (Hopker et al. 2009).
Power output at 2 mmol·l-1 [la-] was unchanged in both groups after the preparatory period,
but E+S improved power output at 2 mmol·l-1 [la-] at 25 weeks. This improvement for E+S
was accompanied by reduced RPE at the power outputs when 2 mmol·l-1 [la-] was
approached. The finding of improved power output at 2 mmol·l-1 [la-] after adding strength
training agrees with a previous study on untrained persons (McCarthy et al. 1995), but
contradicts findings in trained female (Bishop et al. 1999) and male cyclists (Sunde et al.
2009). Interestingly, the latter two studies were performed during the preparatory period only
and, as in the present study, no change was observed. Since E+S increased power output at 2
mmol·l-1 [la-] while E did not, and the groups did not differ in VO2max, an improved cycling
economy in E+S might be expected. An improvement in cycling economy, measured as VO2
at submaximal power outputs, could then have explained the observed increase in power
output at 2 mmol·l-1 [la-]. However, this was not the case, as cycling economy and gross
efficiency did not improve significantly in E+S. The finding of no change in cycling economy
is in accordance with a study in which well-trained cyclists combined heavy strength training
with endurance training (Aagaard et al. 2007). The differences between groups in power
22
output at 2 mmol·l-1 [la-] are therefore likely to be affected by the slightly impaired cycling
economy in E. Indeed, an inverse relationship between VO2max and efficiency has previously
been observed in professional cyclists (Lucia et al. 2002). Similar observations have been
conducted on distance runners (Pate et al. 1992). The added strength training may therefore
contribute to maintenance of the cycling economy, despite increased VO2max. The power
output corresponding to a set [la-] or inflection point obtained during a continuous incremental
exercise test has been suggested to be a more important determinant of endurance cycling
performance than VO2max (Bishop et al. 1998; Coyle et al. 1991). Thus, the improved power
output at 2 mmol·l-1 [la-] potentially reflects superior endurance cycling performance.
40-min all-out trial
Mean power output in the 40-min all-out trial is mainly determined by performance oxygen
consumption and cycling economy (Joyner and Coyle 2008). The performance oxygen
consumption is again largely affected by VO2max and lactate threshold. The findings of
improved VO2max and reduced [la-] at a submaximal power output of 275 W in both groups
after the preparatory period may thus contribute to the improved mean power output in the 40-
min all-out trial at 12 weeks. However, at 13 weeks into the competition period, the further
relative increase in mean power output during the 40-min all-out trial was significantly greater
in E+S than in E. This larger improvement in E+S may be explained by a combination of this
group’s larger relative reduction in [la-] at a power output of 275 W, larger relative increase in
Wmax, further improvement in VO2max into the competition period, as well as a slight
impairment of the cycling economy in E.
The present results agree with previous findings of ~8% increased mean power output during
45-min all-out cycling in national level cyclists after 16 weeks of added heavy strength
23
training (Aagaard et al. 2007). Bastiaans et al. (2001) found similar improvements in a 1-h
time trial for trained cyclists who had a portion of their endurance training replaced with low
loaded explosive strength training. This improvement was, however, not different from
another group of trained cyclists who simply continued their endurance training. It may thus
be suggested that low loaded explosive strength training do not enhance cycling performance
during a 9 week training period. The two latter studies were performed during the preparatory
period. Bishop et al. (1999) reported no improvement in performance for trained female
cyclists in a 1-h time trial after performing concurrent strength and endurance training during
the preparatory period. Notably, the female participants only performed squat exercise, while
four lower body exercises were performed in the present study. Thus, it is possible that the
difference in strength training exercises, gender, and performance test may account for the
divergent findings.
The larger improvements in mean power output during the 40-min all-out trial and in [la-] at
275 W in E+S at 25 weeks, may be related to postponed activation of type II muscle fibers
due to increased strength in type I fibers. A positive correlation between percentage type I
muscle fibers in m. vastus lateralis and efficiency during exercise at a given submaximal
power output has been reported (Coyle et al. 1992; Hansen et al. 2002). An increase in the
strength of type I fibers may delay recruitment of the less economical type II fibers, resulting
in a higher power output at 2 mmol·l-1 [la-]. Delayed recruitment of type II fibers may also
explain the larger reduction in [la-] at a power output of 275 W during the blood lactate profile
test after 25 weeks in E+S. Theoretically, if the hypothesis regarding postponed recruitment
of type II fibers is true, an improved cycling economy should possibly be detected. But this
was not the case. On the other hand, a reduction in RER at all power outputs during the blood
lactate profile test in E+S at 25 weeks may indicate a larger energy supply from fatty acids,
24
leading to a slightly larger demand of VO2. The reduction in RER is also in line with
increased work performed by type I fibers, which, even in endurance trained individuals, are
thought to be superior to type II fibers in their ability to use fat as energy source (Chi et al.
1983). Although reduced RER was observed, no statistically significant changes were
observed in gross efficiency.
We recently published a study on well-trained cyclists, where it was found that the group
completing 12 weeks of strength training improved cycling economy during the last hour of
185-min submaximal cycling more than the control group (Rønnestad et al. 2009). The
improved economy was accompanied by reduced HR, [la-], and improved performance in a 5-
min all-out trial performed immediately following the 185 min of submaximal cycling. We
hypothesized that postponed activation of type II fibers could contribute to the findings.
Furthermore, increases in specific force and unloaded shortening velocity of single muscle
fibers, which did not change the myosin heavy chain expression, have been observed in
response to strength training (Pansarasa et al. 2009). This may also contribute to improved
endurance performance after adding the heavy strength training. Increased rate of force
development (RFD) and/or maximum strength has been hypothesized to positively affect
endurance performance through improved blood flow to the exercising muscles during
exercise (Østerås et al. 2002). This is explained by the assumption that 1) increased RFD may
allow a longer relaxation time and thereby increased blood flow and/or 2) increased maximum
strength may reduce the relative force and thus reduce constriction of the blood flow. In the
present study maximum strength did increase, and increased RFD is usually observed after
strength training periods similar to the present intervention; containing heavy loaded exercises
performed with maximal mobilization in the concentric phase (e.g. Aagaard et al 2002). The
25
improved performance in E+S may therefore be partly due to improved blood flow to the
exercising muscles.
There were no significant differences between groups in the 40-min performance test after the
preparatory period. This may be explained by the fact that, for well-trained endurance athletes
with several years of training, improvements in aerobic performance come in smaller
increments (Paavolainen et al. 1999). Furthermore, it may be hypothesized that the cyclists in
E+S needed more than 12 weeks to fully translate the increased strength into improved
cycling performance. Thus, the performance enhancing effect of the strength training was not
detectable before the gained strength had been maintained for 13 weeks into the competition
period.
In conclusion, performing just one weekly strength maintenance training session for 13 weeks
into a competition period allowed well-trained cyclists to maintain the increases in leg
strength and thigh muscle CSA that were attained during a preceding 12-week preparatory
period. The development of VO2max was not compromised by the strength training. Of even
greater practical importance, the in-season maintenance of the strength training adaptations
resulted in larger improvements in cycling performance and factors relevant for performance,
for both sprint and prolonged cycling as compared to cyclists performing only usual
endurance training.
Acknowledgements
The authors express their thanks to the participants for their time and effort.
No founding was received for this work.
26
Conflict of interest
The authors declare that they have no conflict of interest.
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Figure Captions
Fig. 1 Strength exercises (A) half squat in Smith-machine, (B) recumbent leg press with one
leg at a time, (C) standing one-legged hip flexion, and (D) ankle plantar flexion.
Fig. 2 Thigh muscle cross-sectional area (CSA) separated into area of knee extensors (upper
panels) and knee flexors (lower panels) before the preparatory period (Pre), after the
preparatory period (12 weeks), and 13 weeks into the competition period (25 weeks). One
group of cyclists added heavy strength training to their endurance training (E+S; n=6, panel a
and c) while cyclists in the other group simply performed their usual endurance training (E;
n=6, panel b and d). Mean and each individual data points are presented. *Larger than at Pre
(p<0.05). #The relative change from Pre is larger than in E (p<0.01). ##Larger than in E
(p<0.05)
Fig. 3 1RM in half squat before (Pre), after the 12 week preparatory period (12 weeks), and
13 weeks into the competition period (25 weeks). For explanation of E+S (panel a) and E
(panel b), the reader is referred to Figure 2. Mean and each individual data points are
presented. *Larger than at Pre (p<0.01). #The relative change from Pre is larger than in E
(p<0.01). ##Larger than in E (p<0.01)
32
Fig. 4 Responses during the continuous incremental cycle test before (Pre), at the end of the
preparatory period (12 weeks), and 13 weeks into the competition period (25 weeks). For
explanation of E+S (left panels) and E (right panels), the reader is referred to Figure 2.
*Different from Pre (p<0.05). §Different from 12 weeks (p<0.05). #The relative change from
Pre is larger than in E (p<0.05)
Fig. 5 Mean power output (W) during the 40-min all-out trial before (Pre), at the end of the
preparatory period (12 weeks), and 13 weeks into the competition period (25 weeks). For
explanation of E+S (panel a) and E (panel b), the reader is referred to Figure 2. Mean and
each individual data points are presented. *Larger than at Pre (p<0.05). #The relative change
from Pre is larger than in E (p<0.01)
33
Figure 2
65
85
1
05
1
25
Pre 12 weeks 25 weeks
Subject 7
Subject 8
Subject 9
Subject 10
Subject 11
Subject 12
Mean
b
65
85
105
125
Pre 12 weeks 25 weeks
CSA knee extensors (cm 2)
Subject 1
Subject 2
Subject 3
Subject 4
Subject 5
Subject 6
Mean
a ##
#
* ##
* #
65
85
105
125
Pre 12 weeks 25 weeks
CSA knee flexors (cm 2)
Subject 1
Subject 2
Subject 3
Subject 4
Subject 5
Subject 6
Mean
c #
* #
*
65
85
1
05
1
25
Pre 12 weeks 25 weeks
Subject 7
Subject 8
Subject 9
Subject 10
Subject 11
Subject 12
Mean
d
34
Figure 3
75
100
125
150
175
200
225
250
275
Pre 12 weeks 25 weeks
1RM Half squat (kg)
Subject 1
Subject 2
Subject 3
Subject 4
Subject 5
Subject 6
Mean
##
##
**
##
a
75
100
125
150
175
200
225
250
275
Pre 12 weeks 25 weeks
Subject 7
Subject 8
Subject 9
Subject 10
Subject 11
Subject 12
Mean
b
35
Figure 4
20
25
30
35
40
45
50
55
60 E Pre
E 12 weeks
E 25 weeks
*
*
*
80
100
120
140
160
180
Heart rate (beats·min
-1
)
***
*
§§
20
25
30
35
40
45
50
55
60
VO
2
(ml·kg
-1
·min
-1
)
E+S Pre
E+S 12 weeks
E+S 25 weeks
0.75
0.80
0.85
0.90
0.95
1.00
Respiratory exchange ratio
*
*
*
*
†
0.75
0.80
0.85
0.90
0.95
1.00
12
1
22
2
*
†
80
100
120
140
160
180
***
*
†
†
† †
0
1
2
3
4
5
6
[La
-
] (mmol·l
-1
)
*
#
†
0
1
2
3
4
5
6
†
6
8
10
12
14
16
18
20
125 175 225 275
Power output (W)
Rate of perceived exertion
*
*
†
6
8
10
12
14
16
18
20
125 175 225 275
Power output (W)
p
†
36
Figure 5
Table 1 Strength training program for the cyclists who performed heavy strength training.
Preparatory period
Week 1-3 Week 4-6 Week 7-12
1. Bout 2. Bout 1. Bout 2. Bout 1. Bout 2. Bout
Competition period
Week 13-25
1. Bout
Half squat 3x10RM 3x6RM 3x8RM 3x5RM 3x6RM 3x4RM 2x5 reps @80-85% of 1RM
One-legged leg press 3x10RM 3x6RM 3x8RM 3x5RM 3x6RM 3x4RM 2x5 reps @80-85% of 1RM
One-legged hip flexion 3x10RM 3x6RM 3x8RM 3x5RM 3x6RM 3x4RM 1x6RM
Ankle plantar flexion 3x10RM 3x6RM 3x8RM 3x5RM 3x6RM 3x4RM 1x6RM
220
250
280
310
340
370
400
Pre 12 wks 25 wks
Mean power output (W)
Subject 1
Subject 2
Subject 3
Subject 4
Subject 5
Subject 6
Mean
** #
a
220
250
280
310
340
370
400
Pre 12 wks 25 wks
Subject 7
Subject 8
Subject 9
Subject 10
Subject 11
Subject 12
Mean
**
b
37
Table 2 Results from the incremental cycle test for measurement of maximal oxygen
consumption before (Pre), after the preparatory period (12 weeks), and 13 weeks into the
competition period (25 weeks) in the group that had heavy strength training added to their
endurance training (E+S) and the group which performed usual endurance training only (E).
E+S (n=6)
Pre 12 weeks 25 weeks
E (n=6)
Pre 12 weeks 25 weeks
VO2max (L⋅min-1) 5.20 ± 0.28 5.53 ± 0.36* 5.65 ± 0.36*§ 5.00 ± 0.45 5.28 ± 0.42* 5.27 ± 0.45*
(ml⋅kg-1⋅min-1) 65.2 ± 2.2 69.0 ± 2.4* 73.9 ± 3.2*§ 67.3 ± 2.7 72.5 ± 2.7* 73.4 ± 3.1*
Wmax (W) 420 ± 15 442 ± 22 454 ± 19*# 401 ± 37 412 ± 34 399 ± 33
RER 1.10 ± 0.01 1.07 ± 0.02 1.06 ± 0.01 1.08 ± 0.01 1.06 ± 0.01 1.05 ± 0.01
HRmax (beats⋅min-1) 186 ± 4 187 ± 4 186 ± 4 183 ± 3 183 ± 3 182 ± 4
[La-] (mmol⋅ l-1) 12.9 ± 0.7 14.1 ± 0.6 13.6 ± 0.8 12.0 ± 1.3 12.4 ± 0.8 12.0 ± 0.8
RPE 19.2 ± 0.2 19.0 ± 0.3 19.0 ± 0.0 19.0 ± 0.3 18.7 ± 0.2 18.7 ± 0.4
Values are mean±SE. BM: body mass; VO2max: maximal oxygen consumption; RER: respiratory exchange ratio; HRmax: maximal heart rate; [La-]:
blood lactate concentration; RPE: rate of perceived exertion. *Larger than at Pre (p<0.05). §Larger than at 12 weeks (p<0.05). #The relative change
from Pre is larger than in E (p<0.05).
38
Table 3 Results from the Wingate test before (Pre), after the preparatory period (12 weeks),
and 13 weeks into the competition period (25 weeks). For explanation of E+S and E, the
reader is referred to Table 1.
E+S (n=6)
Pre 12 weeks 25 weeks
E (n=6)
Pre 12 weeks 25 weeks
Peak power output (W) 1470 ± 51 1557 ± 63§ 1557 ± 55§* 1178 ± 123 1162 ± 140 1157 ± 157
Peak power output, body
mass-adjusted (W·kg-1)
18.5 ± 0.4 19.5 ± 0.8 19.9 ± 0.8§* 15.7 ± 1.1 15.8 ± 1.3 16.0 ± 1.6
Mean power output (W) 828 ± 33 814 ± 29 805 ± 39 696 ± 69 683 ± 64 667 ± 68
Mean power output, body
mass-adjusted (W·kg-1)
10.2 ± 0.3 10.2 ± 0.3 10.2 ± 0.4
9.3 ± 0.6 9.4 ± 0.6 9.3 ± 0.7
Fatigue index (W·s-1) 34.0 ± 1.2 38.0 ± 2.0#§ 36.3 ± 3.1
25.6 ± 3.4 24.4 ± 3.8 24.6 ± 4.4
Values are mean±SE. *Larger than at Pre (p<0.01), #The relative change from Pre is larger than in E (p<0.05). §Larger than in E (p<0.05)
