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82
International Journal of Sports Physiology and Performance, 2011, 6, 82-93
© 2011 Human Kinetics, Inc.
Daniel A. Boullosa is with Pós-Graduação Stricto Sensu em Educação Física, Universidade Católica de
Brasília, Brazil. José L. Tuimil is with the Department of Physical Education and Sport, University of A
Coruña, A Coruña, Galicia, Spain. Luis M. Alegre is with the Faculty of Sports Sciences, University of
Castilla–La Mancha, La Mancha, Spain. Eliseo Iglesias is with the Department of Physical Education
and Sport, University of A Coruña, A Coruña, Galicia, Spain. Fernando Lusquiños is with the Depart-
ment of Applied Physics, University of Vigo, Vigo, Spain.
Concurrent Fatigue and Potentiation
in Endurance Athletes
Daniel A. Boullosa, José L. Tuimil, Luis M. Alegre,
Eliseo Iglesias, and Fernando Lusquiños
Purpose: Countermovement jump (CMJ) and maximum running speed over a
distance of 20 m were evaluated for examination of the concurrent fatigue and post-
activation potentiation (PAP) in endurance athletes after an incremental eld running
test. Methods: Twenty-two endurance athletes performed two attempts of CMJ on
a force plate and maximum running speed test before and following the Université
de Montréal Track Test (UMTT). Results: The results showed an improvement in
CMJ height (3.6%) after UMTT that correlated with the increment in peak power
(3.4%), with a concurrent peak force loss (–10.8%) that correlated with peak power
enhancement. The athletes maintained their 20 m sprint performance after exhaus-
tion. Cluster analysis reinforced the association between CMJ and peak power
increments in responders with a reported correlation between peak power and sprint
performance increments (r = .623; P = .041); nonresponders showed an impairment
of peak force, vertical stiffness, and a higher vertical displacement of the center of
mass during the countermovement that correlated with lactate concentration (r =
–0.717; P = .02). Conclusions: It can be suggested that PAP could counteract the
peak force loss after exhaustion, allowing the enhancement of CMJ performance
and the maintenance of sprint ability in endurance athletes after the UMTT. From
these results, the evaluation of CMJ after incremental running tests for the assess-
ment of muscular adaptations in endurance athletes can be recommended.
Keywords: countermovement jump, sprint, maximum aerobic speed, exhaustion,
eld
During recent years, various studies investigated the inuence of neuromuscular
factors on distance running, in particular, the relationship between muscle power
factors and endurance running.1,2 Furthermore, different modalities of strength
training with emphasis on power characteristics have been demonstrated to pro-
mote a higher running economy3–5 and a higher endurance performance.1,6 This
Potentiation After Exhaustion 83
suggests that metabolic adaptations could also be accompanied by neuromuscular
adaptations when a runner improves his running test results after a training period.
Consequently, the evaluation of power concurrently with running performance
should be considered for the monitoring of endurance athletes.
Postactivation potentiation (PAP) refers to the phenomena by which muscular
performance characteristics are acutely enhanced as a result of their contractile
history.7 Some authors8 have reported an acute enhancement of power and jump
capacities after an incremental protocol until exhaustion in a cohort of elite distance
runners. This enhancement is contrary to the expected effect of fatigue on power
characteristics following running until exhaustion.9,10 Other authors11 have shown the
inuence of two exhausting, running protocols on the PAP prole while jumping and
indicated that this PAP has not been reported in a group of physically active nonrun-
ners. Therefore, it may be suggested that the PAP response, after running exercises,
is specic for endurance-trained subjects with different responses detected depending
upon the mode of the running protocol. Furthermore, the paradox of jump enhance-
ment after exhaustion is interesting and may indicate the coexistence of PAP and
fatigue12 where the PAP-fatigue relationship affects subsequent voluntary activity.7
Potentiation is expected to occur after evoked contractions and after near-
maximum or maximum voluntary conditioning exercises in power-trained athletes
when performing explosive tasks.7 Similarly, twitch-potentiation has also been
observed in endurance-trained athletes in evoked contractions after maximal vol-
untary contractions,13 moderate-intensity isometric voluntary contractions,14 and
continuous15 and intermittent running bouts.16 Moreover, PAP has also been reported
in endurance trained athletes in jump performance after intermittent,8 continuous
running exercises,8,17 and incremental protocols.8,11 From these previous studies,
it can be suggested that the nature of the conditioning activity for PAP may be
dependent upon the chronic training adaptations experienced by subjects. While
athletes experienced in endurance training would demonstrate PAP after condition-
ing activities that stimulate slow-twitch bers, those athletes experienced in power
training would experience PAP after conditioning activities that stimulate primarily
on fast-twitch bers. In this regard, some authors8 reported correlations among jump
enhancement, training volume, and maximum aerobic speed (MAS), suggesting a
relationship between muscular chronic adaptations of elite endurance runners and
the acute responses under fatigue. In contrast, others11 failed to observe similar
correlations between variables. Subsequently, it would be important to examine
further the potential relationships among training, running, and mechanisms for PAP.
A countermovement jump (CMJ) is an easy-to-perform test, which is a neu-
romuscular fatigue assessment of athletes.18 Previously, it was suggested that an
enhancement of elastic energy transfer occurs in a fatigued condition in CMJ with
both impairment18 or enhancement8 of performance. Previous studies of distance
runners8,11 evaluated PAP and jump capacity with the ight-time method. However,
the characteristics of the force-time curve during the push-off phase remain still
unknown when looking for mechanical differences when PAP occurs. Another easy
eld test for neuromuscular fatigue evaluation is the maximal 20 m sprint test.9
Interestingly, the velocity loss in this test after a 5 km trial has been related to the
nonfatigued performance.10 Subsequently, mechanical parameters during a CMJ
and sprint performance could be considered valid for the evaluation of concurrent
postexercise PAP and fatigue.
84 Boullosa et al.
Thus, the aim of this work was to study mechanical differences when endur-
ance athletes perform a CMJ on a force plate before and after the Université de
Montréal Track Test (UMTT).19 This eld running test was selected because it is
appropriate for both endurance running evaluation20 and fatiguing exercise.11 In
addition, the maximal sprint velocity over 20 m sprint was evaluated for comparison
between both conditions. The hypothesis was that the PAP and fatigue induced by
the UMTT could be reected in the changes in mechanical parameters during the
CMJ and in maximal sprint velocity over 20 m.
Methods
Participants
Twenty-two experienced endurance athletes (8 female and 8 male endurance run-
ners, and 6 male triathletes) of heterogeneous level (from regional to elite) and
training background volunteered for participation in this study. The sample was
evaluated throughout the months of July to September, immediately following the
end of the runner’s competitive season. However, the triathletes were still competing.
Their characteristics are shown in Table 1. The local ethics committee approved this
study design for experimentation with human participants. All participants were
informed of all procedures and provided informed written consent.
Table 1 Characteristics of participants, mean (SD)
N
= 22 Mean (SD) Range
Male Runners (n = 8)
Age (y) 24 (4.3) 18–28
Height (cm) 179.9 (8.3) 171–196
Body mass (kg) 68.4 (7.5) 54.2–75
% Body fat (% BW) 7.8 (0.7) 6.6–8.9
Maximum aerobic speed (km·h–1) 20.1 (0.6) 19–21
Female Runners (n = 8)
Age (y) 22.5 (5.5) 18–31
Height (cm) 165.5 (5.5) 158–174
Body mass (kg) 53.9 (3.8) 47.6–59
% Body fat (% BW) 13.8 (2.6) 10.1–18.4
Maximum aerobic speed (km·h–1) 18.1 (1) 16–19
Male Triathletes (n = 6)
Age (y) 28.5 (6.2) 18–35
Height (cm) 175.3 (4.6) 171–181
Body mass (kg) 67.2 (4.1) 63.2–73.5
% Body fat (% BW) 7.8 (0.5) 7.3–8.5
Maximum aerobic speed (km·h–1) 18.3 (0.5) 18–19
Note. BW: body weight.
Potentiation After Exhaustion 85
Procedures
Participants were evaluated individually on two occasions. A preliminary ses-
sion in the laboratory was employed for both anthropometric evaluation and
familiarization of participants with CMJ performance. This preliminary session
was conducted between 48 h and 1 wk before the eld evaluation session with
participants advised to avoid strenuous exercise 72 h before. The second session
was conducted on a 400 m outdoor track with climatic conditions as follows:
temperature of 21–28°C, relative air humidity of 70–80%, and barometric pres-
sure of 735–765 mmHg.
Power Performance in Nonfatigued Condition
Participants warmed up by running on the grass for 10 min at an intensity of 60%
of their estimated HRmax with a HR monitor (625x, Polar Electro, Finland). As
part of the warm-up, the athletes practiced two to three CMJ attempts with arms
akimbo immediately after the running exercise.
Recording of jump performance in the nonfatigued condition was conducted
2–3 min after the warm-up and consisted of two maximal CMJ attempts, separated
by at least 15 s. Participants were encouraged to jump as high as possible. The
depth of the countermovement was freely chosen by participants. These jumps
were performed on a force plate (Quattro jump, Kistler, Switzerland) with a sam-
pling rate of 500 Hz, where vertical forces were recorded. The highest jump was
selected for further analysis. Jump height (CMJ) was calculated from the difference
between maximum height of the center of mass (apex) and the last contact of the
toe on the ground during the take-off. Peak force was considered relative to body
weight (BW). Mean and peak power during the push-off phase were also obtained.
Additional parameters for further analysis were the vertical path of center of mass
and normalized vertical stiffness (N·m–1·kg–1).21
Immediately after jump evaluation, participants performed two attempts,
separated by 2 min of recovery, of a maximal running velocity test over 20 m.
Distance for acceleration was freely chosen by participants (ie, 25–40 m) and
performed in progression for achieving a true maximum sprint speed over a 20
m section recorded with a photocell portable system (Chronomaster, Spain)
having an accuracy of +0.001 s. Maximum running speed was calculated from
the recorded lap time.
Endurance Running Evaluation
The cadence of the UMTT was similar to the original (1 km·h–1 every 2 min)19 but
the velocity was imposed by a cyclist with a velocimeter that was previously cali-
brated (SC6501, Shimano, Taiwan). The last completed 2 min stage was considered
as the maximum aerobic speed (MAS). The nal time of the test was also recorded
(TUMTT). This test is highly reproducible in athletic populations with the maximum
aerobic speed demonstrating signicant and high correlations with running per-
formance.20 At the end of the running test, exhaustion was conrmed by an RPE >
19 (6–20 Borg’s scale) and attainment of estimated HRmax. Immediately after the
UMTT, blood samples were taken from the ngertip for lactate measurement with
a portable lactate analyzer (Lactate Scout, Senslab, Germany) for characterization
of effort and as an additional exhaustion criterion (> 8 mmol·L–1).
86 Boullosa et al.
Power Performance in Fatigued Condition
At the end of the UMTT, participants walked to the starting point where the force
platform and the photocells were placed. At the second minute of recovery they
performed two attempts of the CMJ. This recovery time was necessary because
the nal location of the athlete at the end of the UMTT may be uncertain, and also
because it has been demonstrated to be appropriate for our purposes.11 After CMJ
evaluation, participants performed two attempts of the maximal 20 m running test
(third and fth minute of recovery) as previously described. Percentage of changes
of power performance parameters were calculated (Δ) for further analysis.
Statistical Analysis
To conrm a normal distribution for variables, a Kolmogorov-Smirnov test was
performed. Statistical descriptives are shown as means (SD). To assess within-
trial reliability of jump and sprint tests, intraclass correlation coefcients (ICCs)
were calculated. Paired t tests were performed to identify pre- to post-trial UMTT
changes. On the basis of the distribution of the change in CMJ (ΔCMJ), participants
were also categorized as responders and nonresponders (ie, cluster analysis) for
a better analysis of the variance as the distributions of selected parameters were
mainly leptokurtic. The cluster analysis was automatically performed with the
SPSS software (v.16.0.2, Chicago, IL). Square Euclidian distance was chosen
as distance measurement method. A two-way ANOVA (moment × cluster) with
repeated measurements was used to detect signicant differences between condi-
tions and clusters with post hoc analyses (Bonferroni) conducted if necessary. The
factors gender and sport modality were not be considered for analysis because of
their low number and homogeneity. Partial correlation coefcients (adjustment for
gender) were employed for analysis of the relationships between selected param-
eters. Cohen’s D was also performed as a complementary effect size calculation
(D = 0.2, small; D = 0.5, medium; D = 0.8, large).
Results
Running performance for the UMTT resulted in a TUMTT value of 1476 ± 145 s
with a MAS of 18.9 ± 1.2 km·h–1. The HRmax recorded at the end of the running
protocol was 189 ± 11 bpm with a lactate concentration of 9.6 ± 1.9 mmol·L–1.
Reliability for CMJ was high in the nonfatigued (ICC = 0.889) and fatigued
(ICC = 0.939) condition. The UMTT led to a signicant increase in CMJ (ΔCMJ
= 3.6 ± 6.1%; P = .008) and peak power (Δpeak power = 3.4 ± 6.1%; P = .035),
and a signicant decrease in peak force (Δpeak force = –10.8 ± 20.4%; P = .027).
There were no other signicant changes in the remaining parameters although there
was a tendency for a decrease in the vertical path of the center of mass (P = .076)
and vertical stiffness (P = .074) (see Table 2).
Signicant correlations were identied between ΔCMJ and Δpeak power (r =
.658; P = .001) and Δmean power (r = .643; P = .002). Δmean power was correlated
with Δpeak force (r = .857; P = .000) and Δpeak power (r = .722; P = .000) while
Δpeak force was correlated with Δpeak power (r = .480; P = .028) (see Figure
1). No signicant correlations were found between jump or sprint and endurance
performance parameters.
Potentiation After Exhaustion 87
Reliability for sprint performance was high in the nonfatigued (ICC = 0.96)
and fatigued (ICC = 0.959) condition. There was no signicant difference (P =
.993) between sprint performance in the nonfatigued condition (29.3 ± 2.5 km·h–1)
and after the UMTT (29.3 ± 2.5 km·h–1).
Table 2 Mean (SD) values of force-time parameters of the best
CMJ before (Pre; nonfatigued condition) and after (Post; fatigued
condition) the Université de Montréal Track Test. Percentage of
changes (Δ%) are also reported.
Variables Pre Post
Δ
%
CMJ (cm) 29.5 (5.5) 30.6 (5.4) 3.6 (6.1)†
Mean power (W·kg–1) 24.9 (5.5) 24.8 (5.2) –0.1 (8)
Peak power (W·kg–1) 43.3 (10.2) 44.8 (9.7) 3.4 (6.1)*
Vertical displacement of center of mass (cm)
27.4 (6.3) 28.9 (6.6) 4.3 (12.5)
Maximum force (BW) 2.25 (0.26) 2.14 (0.21) –10.8 (20.4)*
Vertical stiffness (N·m–1·kg–1) 99.6 (39.1) 92 (32.2) –9.4 (19.9)
Note. CMJ: countermovement jump; BW: body weight. † P < .01; * P < .05.
Figure 1 — Relationship between the pre–post changes (%) for peak power (ΔPP) with
countermovement jump (circles, continuous line) (ΔCMJ; R2 = .43) and maximum force
(triangles; dashed line) (ΔFi; R2 = .24).
88 Boullosa et al.
Cluster Analysis
Analysis of variance of clusters (see Table 3) revealed signicant differences
between conditions in some mechanical parameters for responders (5 male run-
ners, 5 female runners, and 2 triathletes): ΔCMJ (+4.9%; P = .01), Δpeak power
(+5.8%; P = .038); and for nonresponders: Δvertical path of the center of mass
(+9.7%; P = .043), peak force (–29.9%; P = .000), and a tendency in vertical stiffness
(–16.6%; P = .052; Cohen’s D = 0.48). A signicant moment × cluster interaction
was identied for mean power (P = .000) and peak force (P = .000) with responders
demonstrating greater values compared with nonresponders. Signicant correlations
between ΔCMJ and Δpeak power (r = .752; P = .005), ΔCMJ and Δmean power (r
= .840; P = .001) and between Δpeak power and Δsprint performance (r = .623; P =
.041) were detected for responders. For nonresponders, only a correlation between
lactate concentration and Δvertical path of the center of mass (r = –0.717; P = .02)
was exhibited. No correlations were found between jump and endurance running
performance parameters for any clusters.
Discussion
The rst nding of this study is the conrmation of the PAP experienced by a
group of endurance athletes, from different genders and training backgrounds,
after an incremental running test, which is similar to previous studies with distance
runners.8,11 This PAP was conrmed with the utilization of a force plate for jump
evaluation, whereas prior studies have utilized a ight-time method that overesti-
mates the true ight height22 that could potentially bias results. In this regard, it is
interesting to note the differences in ΔCMJ among studies for well-trained male
runners with one study8 reporting an 8.9% change, and another study11 reporting a
12.7% change. However, the current study found a smaller change of 4.9%. From
these observations, we suggest considering these methodological issues in future
studies, specically with regard to athlete´s posture during CMJ landing on contact
mats.23 Further studies are needed for the assessment of the possible inuence of
the method employed in PAP magnitude.
Regarding mechanical parameters, the signicant correlations found between
ΔCMJ with Δpeak power and Δmean power; Δmean power with Δpeak force and
Δpeak power; and Δpeak force with Δpeak power, demonstrated that those athletes
with the smaller loss of peak force enhanced their CMJ performance via peak power
increments. These relationships between selected parameters could explain that PAP
as CMJ performance is highly related to peak power.24 Further, as the mean power
was related to the overall push-off phase (eccentric plus concentric movement)
and its change (Δmean power) signicantly correlated with Δpeak force, it may
be suggested that participants having a smaller loss of peak force could maintain
the overall mean power and improve the subsequent peak power enhancement as
represented on Figure 1. The reported higher peak concentric and eccentric forces,
and greater peak power values for a higher CMJ support this rationale.25
The most affected parameter by fatigue was peak force (–10.8%), suggesting a
negative inuence of fatigue for the development of maximum forces. Interestingly,
vertical stiffness was affected by fatigue, but this change did not achieve statistical
signicance (–9.4%; P = .109; Cohen’s D = 0.21). Previously, others26 described
89
Table 3 Mean (SD) values of force-time parameters of the best CMJ before (Pre; nonfatigued condition) and
after (Post; fatigued condition) the Université de Montréal Track Test for every cluster considered (Responders;
n = 12; Nonresponders; n = 10). The p value of the moment × cluster interaction for every parameter is also
reported.
Variables
Responders Nonresponders ANOVA 2 × 2
Pre Post Pre Post
P =
CMJ (cm) 29.6 (4.9) 31.2 (4.5)† 29.3 (6.3) 29.9 (6.5) 0.241
Mean power (W·kg–1) 24.1 (4.7) 25.3 (4.6) 25.8 (6.4) 24.2 (5.9) 0.000
Peak power (W·kg–1) 41.9 (8.6) 44.4 (9.1)† 45 (12.1) 45.1 (10.9) 0.053
Vertical displacement of center of mass (cm) 27.6 (6.8) 27.7 (7.4) 27.3 (6.1) 30.2 (5.7)* 0.064
Maximum force (BW) 2.2 (0.3) 2.3 (0.2) 2.3 (0.2) 2.0 (0.1)† 0.000
Vertical stiffness (N·m–1·kg–1) 102.5 (44.2) 100.3 (36.4) 96 (34) 81.9 (24.4)* 0.144
Note. CMJ: countermovement jump; BW: body weight. † P < .01; * P < .05.
90 Boullosa et al.
the effect of fatigue on the biceps femoris, rectus femoris, gastrocnemius and vastus
lateralis in elite endurance runners during the last stages of an incremental running
protocol. In this regard, it is tempting to establish a relationship between the fatigue
of these muscle groups and the smaller capacity for the development of force in
the deeper positions of the center of mass during the countermovement. Neverthe-
less, the highest capacity for developing PAP in the slighter fatigued athletes is
in agreement with the previously suggested relationship between the lower level
of fatigue and higher potentiation whereby both phenomena coexist and could be
simultaneously modied with training intervention.12
Another possible mechanism for this PAP may include an enhancement of elas-
tic energy transfer8,18 in CMJ after fatiguing tasks. These prior studies suggested an
enhancement of elastic energy in the fatigued state via the difference between CMJ
and squat jump performances18 and the higher mechanical power with a reduction
in EMGrms of the knee extensor muscles during half squats.8 Others24 suggested
that peak power may not be a good measure of the working capacity of any muscle
and may be an indication of how effectively energy is transferred between body
segments. From these observations, we may suggest that PAP itself could explain
these mechanical changes counteracting the force loss in the eccentric action and
increasing power production in the concentric action.
The maintenance of maximum sprint performance in the fatigued condition is
surprising given the previous reported impairment of sprint ability after a 10 km trial9
and after a 5 km trial10 in endurance runners. Previously, some authors9 did not nd
any difference between low- and high-caliber athletes in sprint performance after
a 10 km. More recently, others10 found a correlation between sprint ability before
a 5 km trial and the velocity loss after this running trial. As we did not nd any
correlation between similar parameters in the current study, it may be speculated
that running test mode (ie, incremental vs distance trial) may be important for the
consideration of fatigue origin and its inuence on sprint performance under fatigue.
As we did not nd a deterioration of this ability after conduction of the ramp test,
it may be suggested—for a practical point of view—the evaluation of maximum
sprint ability after incremental tests allowing coaches some economy in time evalu-
ation. While our testing schedule was designed for a proper examination of the PAP
on two different exercises in a eld setting, further studies are needed for a more
precise evaluation of the sprint ability after incremental tests compared with other
testing modes,9,10 specically with regard to the different origins of fatigue among
conditions, while this capacity is very important to the nal rushes of the races.
For a better understanding of the mechanical differences, we decided to incor-
porate cluster analysis, as members of the same cluster are likely to have more
similar responses. Two clusters of endurance athletes were obtained from the dif-
ferent magnitude of the ΔCMJ. These clusters were categorized as responders (n
= 12; ΔCMJ = 5 ± 6.9%) and nonresponders (n = 10; ΔCMJ = 1.9 ± 4.9%). From
this analysis, responders conrmed an improvement of CMJ in fatigued condition
via enhancement of peak power. Interestingly, this group demonstrated a correla-
tion between Δpeak power and Δsprint performance, suggesting the simultaneous
inuence of PAP during these different exercises. Nonresponders demonstrated a
signicant impairment of peak force and vertical stiffness with a higher value for
vertical displacement, reinforcing the negative inuence of local fatigue on the
capability of athletes to demonstrate PAP during power performance. Moreover,
Potentiation After Exhaustion 91
a correlation was found between lactate concentration and the changes in vertical
displacement during jumping. The sign of this correlation is opposite to the expected
inuence of lactate on fatigue as it means that the higher the lactate concentration,
the lower the depth of the countermovement for this cluster. Therefore, while it may
be suggested that there is a complex response of the neuromuscular system under
fatigue from all these results, the ANOVA analysis (moment × cluster) revealed
some interactions for maximum force and mean power with both tendencies detected
for vertical displacement and peak power. Subsequently, it was conrmed there is
a differentiated response of every cluster after the fatiguing, running exercise with
emphasis on the role of the force preservation for the subsequent improvement in
jump performance.
The absence of correlations between endurance running and jump or sprint per-
formance parameters is contrary to a previous study8 but in agreement with another
one.11 These authors8 found some correlations of ΔCMJ with training volume,
MAS, CMJ, and 20 m sprint performance. While we did not nd any correlation
regarding these parameters, it is interesting to note the superior ΔCMJ value of the
higher vs. lower quintile of TUMTT (8% vs 1.4%) s in the current study independently
of the level and the training background of the athletes. From this observation, it
may be suggested that the number of stage increments during the incremental test
could favor athletes who run a greater proportion of their time during the UMTT at
submaximal intensities,27 experiencing a greater musculature stimulation14 for the
subsequent PAP in a dose-response manner. Previous evidence of a greater ΔCMJ
after a tempo running (40 min at 80% of maximum aerobic speed; ΔCMJ = 14.5%)
compared with an incremental protocol (ΔCMJ = 8.9%);8 and the UMTT (ΔCMJ =
12.7%) compared with the time limit at maximum aerobic speed (ΔCMJ = 3.5%),11
support this rationale. Further, some of the advanced athletes in the current study
were included in the nonresponders cluster despite having a higher MAS in respect
to their counterparts. Therefore, this would conrm that the tolerance to muscular
fatigue may be the more important factor for the achievement of a higher jump
height after exhaustion independently of the MAS recorded.
Practical Applications
We suggest coaches evaluate the CMJ performance after incremental tests as an
easy-to-perform test reecting muscular fatigue tolerance and PAP in endurance
running. Given the simultaneous inuence of training in muscular fatigue and
potentiation,12 it may be considered the evaluation of vertical jump performance
after ramp tests for the assessment of muscular adaptations in endurance athletes.
Moreover, it may be suggested that the appropriateness of the evaluation of the
maximum sprint ability after incremental tests as this capacity has demonstrated
no deterioration after exhaustion when compared with nonfatigued conditions.
For example, if an athlete experienced PAP in a CMJ after an incremental test and
some weeks later the same athlete did not experience PAP with no changes in his
MAS and VO2max, this could be interpreted as an impairment with his muscular
capabilities with no changes in his metabolic adaptations.
Although a mechanical explanation for this PAP was demonstrated, it should
be noted that neither the molecular basis nor the neuromuscular parameters were
explored in this study. In this regard, some authors28 have shown the different
92 Boullosa et al.
interaction between fatigue and potentiation at different muscle lengths, suggest-
ing a link with our study in which a maximum force preservation was found with
a subsequent peak power enhancement, where the former is typically at longer
and the latter at shorter muscle lengths. Consequently, further studies may need to
address these aspects for a better understanding of this phenomenon.
Another practical application could be to perform plyometrics immediately
after non- exhaustive running exercises, allowing the benet of the PAP as in other
sport modalities (ie, complex training).29 Nevertheless, this question requires further
experimental research for the assessment of the higher effectiveness of this training
method if compared with other forms of concurrent strength and endurance training.
Conclusions
In summary, PAP was demonstrated after an incremental exhaustive protocol in
endurance athletes with higher CMJ performance in those athletes with concur-
rent higher peak power increments and maximum force preservation. In addition,
maintenance of maximum running velocity after exhaustion may be related to
PAP response, and athletes who run further during a UMTT probably stimulates
musculature more intensely at submaximal intensities resulting in a greater PAP.
Maximum force preservation in a CMJ after a ramp test may be the more important
factor for PAP in the evaluation of muscular adaptations of endurance athletes.
Acknowledgments
This study did not receive any nancial support. We wish to thank Antxón Gorrotxategi of
Biolaster S.L for his support for lactate analysis. We want also to recognize the technical
assistance of Félix Quintero and the helpful comments and English revisions of Anthony
S. Leicht and Natasha Carr.
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