published: 08 March 2017
Habituation Training Improves
Locomotor Performance in a Forced
Running Wheel System in Rats
Angel Toval1,2,Raúl Baños 1,2 ,Ernesto De la Cruz3,Nicanor Morales-Delgado1,2,
Jesús G. Pallarés4,Abdelmalik Ayad1,2,Kuei Y. Tseng 5and Jose L. Ferran 1,2 *
1Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia, Murcia, Spain, 2Institute of
Biomedical Research of Murcia (IMIB), Virgen de la Arrixaca University Hospital, University of Murcia, Murcia, Spain,
3Department of Physical Activity and Sport, Faculty of Sport Science, University of Murcia, Murcia, Spain, 4Human
Performance and Sports Science Laboratory, University of Murcia, Murcia, Spain, 5Department of Cellular and Molecular
Pharmacology, The Chicago Medical School at Rosalind Franklin University, North Chicago, IL, USA
University of Minho, Portugal
University of Lausanne, Switzerland
Louisiana State University Health
Sciences Center, USA
Jose L. Ferran
Received: 01 November 2016
Accepted: 24 February 2017
Published: 08 March 2017
Toval A, Baños R, De la Cruz E,
Morales-Delgado N, Pallarés JG,
Ayad A, Tseng KY and Ferran JL
(2017) Habituation Training Improves
Locomotor Performance in a Forced
Running Wheel System in Rats.
Front. Behav. Neurosci. 11:42.
Increasing evidence supports that physical activity promotes mental health; and regular
exercise may confer positive effects in neurological disorders. There is growing number
of reports that requires the analysis of the impact of physical activity in animal models.
Exercise in rodents can be performed under voluntary or forced conditions. The former
presents the disadvantage that the volume and intensity of exercise varies from subject
to subject. On the other hand, a major challenge of the forced training protocol is the
low level of performance typically achieved within a given session. Thus, the aim of the
present study was to evaluate the effectiveness of gradual increasing of the volume and
intensity (training habituation protocol) to improve the locomotor performance in a forced
running-wheel system in rats. Sprague-Dawley rats were randomly assigned to either
a group that received an exercise training habituation protocol, or a control group. The
locomotor performance during forced running was assessed by an incremental exercise
test. The experimental results reveal that the total running time and the distance covered
by habituated rats was signiﬁcantly higher than in control ones. We conclude that the
exercise habituation protocol improves the locomotor performance in forced running
Keywords: physical activity, exercise, rodents, familiarization protocols, acclimation protocols
According to the World Health Organization (2010), the lack of physical activity is the fourth
leading risk factor for global human mortality. For instance, reduced physical activity is
associated with higher risks of developing obesity, type 2 diabetes, osteoporosis, depression
and cardiovascular diseases (World Health Organization, 2010; Dishman et al., 2013; Mora-
Rodriguez et al., 2016). On the other hand, there is growing evidence supporting a positive
impact of increasing regular levels of physical activity on public health (Dishman et al., 2006;
Hillman et al., 2008; van Praag, 2009; Vivar et al., 2012). These studies suggest that motor
skill training and regular exercise are beneficial to sustaining proper executive functions of
cognition and learning (e.g., motor learning in the spinal cord; Edgerton et al., 2004; Hillman
et al., 2008), and in some cases it may confer protective effects against the onset of neurological
disorders including Parkinson’s disease (Smith and Zigmond, 2003), Alzheimer’s dementia
(Cotman and Berchtold, 2002) and stroke (Stummer et al., 1994). However, the neurobiological
Frontiers in Behavioral Neuroscience | www.frontiersin.org 1March 2017 | Volume 11 | Article 42
Toval et al. Habituation Effects in Forced Wheel
mechanisms associated with physical activity are not entirely
known, partly due to a lack of uniformity and parameterization
in experimental protocols employed to assess the impact
of exercise in animal models. For example, rodent studies
using running-wheels often employ protocols that allow
ad libitum access to the wheel. While such an approach
has its advantages, both the intensity and volume varies
significantly from subject to subject due to the ‘‘voluntary’’
nature of the experimental design (van Praag et al., 2005;
Kregel et al., 2006; Leasure and Jones, 2008; Creer et al.,
2010; Kobilo et al., 2011; Marlatt et al., 2012). One way
to overcome these challenges is to implement a forced
running-wheel protocol in which the same training load is
applied to all subjects (Auriat et al., 2006; Shimizu and
Yamanouchi, 2011; Wang et al., 2013; Chen et al., 2014).
It becomes clear from these studies that the inclusion
of a pretraining stage of habituation prior to the testing
phase is a crucial step to achieving better performances in
response to increasing running demands (Dick, 2007). Thus,
the aim of the present study is to develop and evaluate a
protocol of habituation training to enhance the locomotor
performance of young adult rats subjected to a progressive
incremental running load test in a forced running-wheel system
(Bentley et al., 2007).
MATERIALS AND METHODS
All experimental procedures were approved by the University of
Murcia’s animal care and use committee according to the Spanish
regulation (Royal Decree 1201/2005) and European Union
Directive 2003/65/EC of the European Parliament (Amending
Council Directive 86/609/EEC) guide for care and use of
Animals and Experimental Groups
Young adult male Sprague-Dawley rats (Laboratory Animals
Facilities at the University of Murcia) were group housed
(2–3 rats/cage) and kept in a 12:12 h light/dark cycle room
(dark period from 8 AM to 8 PM) at 21–23◦C and 55 ±5%
of relative humidity, with food and water available ad libitum.
Rats were randomly assigned to receive either the protocol
of habituation training (habituated) or not (non-habituated)
for eight consecutive days. The locomotor performance to
incremental intensities of forced running was assessed at 1, 3,
31 and 33 days post-last habituation session.
Six polycarbonate motor running-wheels were purchased
from Lafayette-Campdem system (80805A model, dimensions
129.54 ×45.47 ×42.93 cm). The internal surface of the
running-wheel was covered with custom-made denim fabric
to provide a smooth flatten running surface (Figures 1A–C).
The habituation phase is comprised of 10 sessions distributed
across 8 days of training. During these sessions, both intensity
(speed) and volume (time) were increased following an upward
progressive pattern as summarized in Figures 1D,F. Once the
habituation phase is completed, rats were subjected to the
first incremental exercise test 24 h after the last habituation
session. In order to determine whether the habituation sessions
exert an enduring impact on forced running performance,
rats were tested again at 3, 31 and 33 days from the last
session of habituation training. During the testing phase of
incremental forced running, a defined speed of 9 m/min is
introduced at the beginning of each test followed by increments
of 0.9 m/min every 5 min until a failure to maintain a
running pattern becomes apparent (Figure 1E). Criteria to
stop the incremental test include jumping, crawling and/or
rolling within the running-wheel. Typically, rats are removed
from the running-wheel and the test stopped if two or more
consecutive uncontrolled laps are detected. The time spent in the
running wheel was determined from the beginning of the test
to its termination when the animal fails to maintain a running
All data were presented as mean ±standard error of the
mean. A two-tailed student’s t-test was used for two-group
comparison involving a single continuous variable and a one-way
repeated measures analysis of variance (ANOVA) test was used
for intra-subjects multiple comparison. Differences between the
experimental groups were considered statistically significant at
P<0.05 (StatSoft, Tulsa, OK, USA).
Comercially available running-wheels were modified to
include a custom-made denim fabric into the internal
surface of the wheel to provide a smooth flatten running
surface (Figures 1A–C). In order to assess the impact of
habituation training, a cohort of young adult male Sprague-
Dawley rats were subjected to a protocol of habituation
comprised of 10 sessions in 8 days during which the
intensity (speed) and the volume (time) of the training
sessions were increased following an upward progressive
pattern (Figures 1D–F). We observed a 100% success rate
response, that is, all animals (n= 23) tested with this tranining
protocol managed to complete the entire 8 days of habituation
We next developed a progressive incremental running load
test (Figure 1E) to assess the impact of habituation training
on locomotor performance. Relative to the non-habituated
group (n= 12), rats that underwent the habituation training
phase exhibited a six fold increase in performance to the
incremental running load test as revealed by the time and
distance spent in the wheel (Figure 2). While most of the
animals from the non-habituated group failed to pass the
first 5 min step of the incremental test, habituated rats
run an average of ∼32 min covering a mean distance of
∼370 m when tested 24 h after the last habituation session
Finally, the incremental test was repeated to evaluate long
term effects of the habituation. The locomotor performance at
3 days remains similar; however it is significantly decreased
Frontiers in Behavioral Neuroscience | www.frontiersin.org 2March 2017 | Volume 11 | Article 42
Toval et al. Habituation Effects in Forced Wheel
FIGURE 1 | (A) Forced motor wheel with aluminum bars in the running surface. (B) Running surface of the wheel covered by denim fabric. (C) Forced motor wheel
system during a running session. (D) The schedule shows the exercise program developed during the habituation exercise protocol. The speed, time and number of
sessions by day are described. The incremental test is developed after 24 h ﬁnished the habituation, and repeated at 3, 31 and 33 days later. (E) This graphic is a
representation of time variation (Xaxis) in relation to the speed variation (Yaxis) during the development of the incremental exercise test. Notice that every 5 min the
speed changes increasing in 0.9 m/m giving the aspect of steps. (F) Bars and lines graph which represents the training load in each day (Xaxis) of the habituation
protocol. Bars indicate time of running (Yaxis, left). Line indicates speed (Yaxis, right). The training load, speed and time followed an upward progressive pattern.
WU, warming up phase.
both at 31 and 33 days (habituated rats run an average
of ∼16/18 min covering a mean distance of ∼162/194 m;
respectively; Figures 3A,B).
These results support that the habituation period improves
the locomotor performance in forced running wheels; but
this effect is progressively drecreased without a permanent
The present study was developed to evaluate the impact of
an habituation training in the locomotor performance, using a
forced running wheel system in young adult rats. It is known
that wild rats cover long distances during the night, running
bursts of short periods at high speeds (Tchernichovski and
Benjamini, 1998). A similar pattern of running is detected
in voluntary exercise laboratory paradigm, that allow rats to
reach higher intensities and cover longer distances than in
forced exercise; but restricting the posibility to manage intensity
and volume of running (training load; Leasure and Jones,
2008). This situation highlights the difficulty of the voluntary
running to do precise correlations between training load and
the observed effects (van Praag et al., 2005; Leasure and Jones,
2008; Creer et al., 2010; Kobilo et al., 2011; Marlatt et al.,
2012). On the other hand, in forced conditions, rats run during
larger periods of time but at lower speed than observed during
voluntary running (Narath et al., 2001; Leasure and Jones, 2008).
Although forced models are consistent with the uniformity of
the physical activity carried out for the group of rats, running
on a treadmill or a motorized wheel can be a challenge for
the animals. In fact, as many as 10% of the rats refuse to walk
or run on a treadmill; and these animals must be removed
from exercise studies (Jasperse and Laughlin, 1999; Koch and
Britton, 2001; Kregel et al., 2006). Our results support that
Frontiers in Behavioral Neuroscience | www.frontiersin.org 3March 2017 | Volume 11 | Article 42
Toval et al. Habituation Effects in Forced Wheel
FIGURE 2 | (A) The graph represents the total time of running endured during
the incremental test comparing non-habituated (blue) and habituated (orange)
young adult rats. Individual measures are indicated by diamonds and the
mean comparison by bars (non habituated: X= 5.42 ±0.5 min; habituated:
X= 31.70 ±1.8 min). (B) The graph represents the total distance covered
during the incremental test comparing non-habituated (blue) and habituated
(orange) rats. Individual measures are indicated by diamonds and the mean
comparison by bars (non habituated: X= 49.57 ±4.87 m; habituated:
X= 368.29 ±25.49 m). ∗∗∗p<0.0001; two-tailed student’s t-test.
habituation exercise training are key to get better locomotor
performances to develop succesful training programs in forced
Only a few of the current works in forced running paradigm
consider the implementation of an habituation phase as a good
strategy to reduce the number of rats classified as nonrunners
(Kregel et al., 2006; O’Dell et al., 2007; Chen et al., 2014).
For this aim the animals are introduced in treadmills or
motor wheels with a gradual increase in training load. This
FIGURE 3 | (A) The graph represents the total time of running of each
individual (gray lines) and the mean of time (orange line) during the four
incremental tests carried out at 1 day after the completion of the habituation
phase and repeated after 3 (X= 27.9 ±1.74 min), 31 (X= 15.81 ±1.46 min)
and 33 (X= 18.58 ±1.54 min) days. (B) The graph represents the total
distance covered during the four incremental tests for each individual (gray
lines) and the mean of distance (orange line) of habituated rats after 1, 3
(X= 314.99 ±24.2 m), 31 (X= 162.27 ±17.29 m) and 33
(X= 194.95 ±18.53 m) days. A comparison between tests at 1 and 3 day vs.
performed at 31 and 33 day show statystically signiﬁcant differences
(p<0.002; one-way repeated measures analysis of variance (ANOVA)).
condition may be relevant to improve locomotor performance
and minimize potential injures that can occur in this new
environment for the rodents. In our study a 100% of rats
finished the whole running habituation period. However, the
habituation protocol is absent in some studies using forced
motor wheel; which maintain a constant intensity and volume
from the beginning and throughout all the sessions during
their programs (Clement et al., 1993; Ji et al., 2014). The
intensity of the exercise developed in these works during the
training protocol was between 1.22 m/min and 12 m/min;
that is lower in comparison with other forced protocols that
includes a progressive increment in the training load, and
reaches a maximum speed of 30 m/min (Clement et al.,
1993; Leasure and Jones, 2008; Chen et al., 2014; Ji et al.,
2014). Some works developed habituation-like protocols, that
consist in an increase of training load pattern during the
entire training period. Under this conditions the highest speed
reached during the training protocol was between 12 m/min
and 14 m/min (Sandrow-Feinberg et al., 2009; Caton et al.,
2012; Griesbach et al., 2013). However, others works that
implement pretraining sessions do not report the training load
details of the protocol employed, such us duration, speed
or number of sessions; but reported a maximum speed of
21 m/min (O’Dell et al., 2007; Hu et al., 2010;Kennard and
Woodruff-Pak, 2012). Finally, only few studies indicate all
the detailed features of the habituation protocol developed;
reaching the highest speed (30 m/min; Auriat et al., 2006;
Shimizu and Yamanouchi, 2011; Wang et al., 2013; Chen et al.,
2014). According to Chen et al. (2014), running behavior
in motor wheels for rodents is more laborious than the
linear motion of the treadmill, in particular in the absence
of an adaptive learning stage. Our results demonstrated that
habituated rats can sustain a higher forced running speed
when compared to the non-habituated group. Interestingly,
such locomotor improvement is transient as the forced running
speed decreases progressively over time within a period of
Several mechanisms could contribute to sustaining a higher
running speed following a progressive habituation protocol
to the running wheel. It is well known that physical activity
produces biochemical changes that improves the muscular
erobic metabolism (Terjung and Hood, 1986). While data on
how a forced running wheel affects muscular endurance are
lacking, evidences from a number of studies using treadmill
suggest that a 60 min/day/1 week of running at 25 m/min
is needed to induce muscular endurance as determined by
changes in cytochrome c, citrate synthase, 3-Ketaocid-CoA
transferase (Booth and Holloszy, 1977;Terjung, 1979; Dudley
et al., 1982), and myoglobin concentration (Lawrie, 1953;
Pattengale and Holloszy, 1967; Terjung and Hood, 1986).
In this regard, it is unlikely that 7 days of progressive
augmentation in duration and intensity reaching a maximal
speed of 9 m/min for 1 h during the last day is sufficient
to elicit adaptive changes in muscular endurance. Another
contributing factor is stress. Stress hormones are known
to increase during forced exercise (Saito and Soya, 2004;
Chen et al., 2016), which in turn are increased during
Frontiers in Behavioral Neuroscience | www.frontiersin.org 4March 2017 | Volume 11 | Article 42
Toval et al. Habituation Effects in Forced Wheel
acute running according to exercise intensity and duration
(Chennaoui et al., 2002; Kawashima et al., 2004; Saito and
Soya, 2004; Chen et al., 2016). Acute stress conditions promote
fight-fight responses producing elevation of peripheral blood
pressure and heart rate; and facilitates energy utilization (Maier
et al., 1998; Moraska et al., 2000; Norris and Carr, 2013).
However, our habituation protocol reaches a maximal speed
of 9 m/min only during the last day for 1 h; and the
evidence from a number of studies using treadmill suggest
that a running speed of at least 25 m/min (just above the
lactate threshold) is required to induce changes in blood lactate,
plasma ACTH, plasma glucose and adrenaline (Timofeeva
et al., 2003; Saito and Soya, 2004; Soya et al., 2007; Chen
et al., 2016). One study showed that activation of CRH
neurons in the paraventricular nucleus emerges following
1 h of acute forced running wheel (Yanagita et al., 2007),
yet data showing changes in stress hormones are currently
Based on currently available literature, it is possible that a
change in the dopaminergic system may contribute to enhance
the forced running-wheel performance observed following the
habituation training. It has been shown that pharmacological
activation of the dopaminergic system is sufficient to improve
motor coordination and its endurance (Tamasy et al., 1981;
Freed and Yamamoto, 1985; Boldry et al., 1991; Meeusen and
De Meirleir, 1995; Sutoo and Akiyama, 1996; Chen et al.,
2016). Future studies are warranted to determine the role
of dopamine and related catecholamines in sustaining better
locomotor performance in a forced running-wheel system.
Further studies using metabolic chambers or implanted chip
systems will be essential to develop the best training condition
and standardized exercise training programs in rodents. A
rigorous analysis of physiological variations such us VO2max,
lactate threshold, heart rate or body composition, a set of data
that is currently used in elite sports training in humans, is
necessary to adapt the training program to the specific features
of each experimental subject (Copp et al., 2009; Zhou et al.,
AT and JLF: study conception and design, data collection and
analysis, interpretation, drafting and revising the manuscript.
RB: data collection and analysis, interpretation, drafting and
revising the manuscript. EDC: study conception and design,
data collection and analysis, interpretation, and revising the
manuscript. NM-D: data collection and analysis, revision
of the manuscript. JGP: study conception and design, data
collection and analysis, revision of the manuscript. AA: data
analysis, interpretation, revision of the manuscript. KYT: study
conception and design, data analysis, interpretation, revision of
the manuscript. All authors have approved the final manuscript
Granted by MAPFRE Foundation (2014); and the Spanish
Ministry of Science and Technology (MEC) and European
Regional Development Fund (FEDER; BFU2014-57516P to JLF).
The authors gratefully acknowledge helpful comments and
laboratory support from Luis Puelles.
Auriat, A. M., Grams, J. D., Yan, R. H., and Colbourne, F. (2006). Forced exercise
does not improve recovery after hemorrhagic stroke in rats. Brain Res. 1109,
183–191. doi: 10.1016/j.brainres.2006.06.035
Bentley, D. J., Newell, J., and Bishop, D. (2007). Incremental exercise test design
and analysis: implications for performance diagnostics in endurance athletes.
Sports Med. 37, 575–586. doi: 10.2165/00007256-200737070-00002
Boldry, R. C., Willins, D. L., Wallace, L. J., and Uretsky, N. J. (1991). The role
of endogenous dopamine in the hypermotility response to intra-accumbens
AMPA. Brain Res. 559, 100–108. doi: 10.1016/0006-8993(91)90292-4
Booth, F. W., and Holloszy, J. O. (1977). Cytochrome c turnover in rat skeletal
muscles. J. Biol. Chem. 252, 416–419.
Caton, S. J., Bielohuby, M., Bai, Y., Spangler, L. J., Burget, L., Pfluger, P.,
et al. (2012). Low-carbohydrate high-fat diets in combination with daily
exercise in rats: effects on body weight regulation, body composition and
exercise capacity. Physiol. Behav. 106, 185–192. doi: 10.1016/j.physbeh.2012.
Chen, C. C., Chang, M. W., Chang, C. P., Chan, S. C., Chang, W. Y.,
Yang, C. L., et al. (2014). A forced running wheel system with a microcontroller
that provides high-intensity exercise training in an animal ischemic stroke
model. Braz. J. Med. Biol. Res. 47, 858–868. doi: 10.1590/1414-431x201
Chen, C., Nakagawa, S., An, Y., Ito, K., Kitaichi, Y., and Kusumi, I. (2016). The
exercise-glucocorticoid paradox: how exercise is beneficial to cognition, mood,
and the brain while increasing glucocorticoid levels. Front. Neuroendocrinol.
44, 83–102. doi: 10.1016/j.yfrne.2016.12.001
Chennaoui, M., Gomez Merino, D., Lesage, J., Drogou, C., and Guezennec, C. Y.
(2002). Effects of moderate and intensive training on the hypothalamo-
pituitary-adrenal axis in rats. Acta Physiol. Scand. 175, 113–121. doi: 10.1046/j.
Clement, H. W., Schäfer, F., Ruwe, C., Gemsa, D., and Wesemann, W.
(1993). Stress-induced changes of extracellular 5-hydroxyindoleacetic acid
concentrations followed in the nucleus raphe dorsalis and the frontal cortex
of the rat. Brain Res. 614, 117–124. doi: 10.1016/0006-8993(93)91024-m
Copp, S. W., Davis, R. T., Poole, D. C., and Musch, T. I. (2009). Reproducibility of
endurance capacity and VO2peak in male Sprague-Dawley rats. J. Appl. Physiol.
106, 1072–1078. doi: 10.1152/japplphysiol.91566.2008
Cotman, C. W., and Berchtold, N. C. (2002). Exercise: a behavioral intervention
to enhance brain health and plasticity. Trends Neurosci. 25, 295–301.
Creer, D. J., Romberg, C., Saksida, L. M., van Praag, H., and Bussey, T. J. (2010).
Running enhances spatial pattern separation in mice. Proc. Natl. Acad. Sci.
USA107, 2367–2372. doi: 10.1073/pnas.0911725107
Dick, F. W. (2007). Sports Training Principles. An Introduction to Sports Science.
6th Edn. New York, NY: Bloomsbury Sport.
Dishman, R. K., Berthoud, H. R., Booth, F. W., Cotman, C. W., Edgerton, V. R.,
Fleshner, M. R., et al. (2006). Neurobiology of exercise. Obesity 14, 345–356.
Dishman, R., Heath, G., and Lee, I. M. (2013). Physical Activity Epidemiology.
Champaign, IL: Human Kinetics.
Dudley, G. A., Abraham, W. M., and Terjung, R. L. (1982). Influence of exercise
intensity and duration on biochemical adaptations in skeletal muscle. J. Appl.
Physiol. Respir. Environ. Exerc. Physiol. 53, 844–850.
Frontiers in Behavioral Neuroscience | www.frontiersin.org 5March 2017 | Volume 11 | Article 42
Toval et al. Habituation Effects in Forced Wheel
Edgerton, V. R., Tillakaratne, N. J., Bigbee, A. J., de Leon, R. D., and
Roy, R. R. (2004). Plasticity of the spinal neural circuitry after injury.
Annu. Rev. Neurosci. 27, 145–167. doi: 10.1146/annurev.neuro.27.070203.
Freed, C. R., and Yamamoto, B. K. (1985). Regional brain dopamine metabolism:
a marker for the speed, direction, and posture of moving animals. Science 229,
62–65. doi: 10.1126/science.4012312
Griesbach, G. S., Tio, D. L., Nair, S., and Hovda, D. A. (2013). Temperature
and heart rate responses to exercise following mild traumatic brain injury.
J. Neurotrauma 30, 281–291. doi: 10.1089/neu.2012.2616
Hillman, C. H., Erickson, K. I., and Kramer, A. F. (2008). Be smart, exercise your
heart: exercise effects on brain and cognition. Nat. Rev. Neurosci. 9, 58–65.
Hu, X., Zheng, H., Yan, T., Pan, S., Fang, J., Jiang, R., et al. (2010).
Physical exercise induces expression of CD31 and facilitates neural function
recovery in rats with focal cerebral infarction. Neurol. Res. 32, 397–402.
Jasperse, J. L., and Laughlin, M. H. (1999). Vasomotor responses of soleus
feed arteries from sedentary and exercise-trained rats. J. Appl. Physiol. 86,
Ji, J. F., Ji, S. J., Sun, R., Li, K., Zhang, Y., Zhang, L. Y., et al. (2014).
Forced running exercise attenuates hippocampal neurogenesis impairment
and the neurocognitive deficits induced by whole-brain irradiation via the
BDNF-mediated pathway. Biochem. Biophys. Res. Commun. 443, 646–651.
Kawashima, H., Saito, T., Yoshizato, H., Fujikawa, T., Sato, Y., McEwen, B. S.,
et al. (2004). Endurance treadmill training in rats alters CRH activity
in the hypothalamic paraventricular nucleus at rest and during acute
running according to its period. Life Sci. 76, 763–774. doi: 10.1016/j.lfs.2004.
Kennard, J. A., and Woodruff-Pak, D. S. (2012). A comparison of low-and
high-impact forced exercise: effects of training paradigm on learning
and memory. Physiol. Behav. 106, 423–427. doi: 10.1016/j.physbeh.2012.
Kobilo, T., Liu, Q.-R., Gandhi, K., Mughal, M., Shaham, Y., and van
Praag, H. (2011). Running is the neurogenic and neurotrophic stimulus
in environmental enrichment. Learn. Mem. 18, 605–609. doi: 10.1101/lm.
Koch, L. G., and Britton, S. L. (2001). Artificial selection for intrinsic
aerobic endurance running capacity in rats. Physiol. Genomics 5,
Kregel, K. C., Allen, D. L., Booth, F. W., Fleshner, M. R., Henriksen, E. J.,
Musch, T. I., et al. (2006). Resource Book for the Design of Animal Exercise
Protocols. Bethesda, MD: American Physiological Society.
Lawrie, R. A. (1953). Effect of enforced exercise on myoglobin concentration in
muscle. Nature 171, 1069–1070. doi: 10.1038/1711069a0
Leasure, J. L., and Jones, M. (2008). Forced and voluntary exercise differentially
affect brain and behavior. Neuroscience 156, 456–465. doi: 10.1016/j.
Maier, S. F., Fleshner, M., and Watkins, L. R. (1998). ‘‘Neural, endocrine, and
immune mechanisms of stress-induced immunomodulation,’’ in New Frontiers
in Stress Research: Modulation of Brain Function, eds A. Levy, E. Grauer,
D. Ben-Nathan and E. R. de Kloet Chur (Switzerland: Harwood Academic),
Marlatt, M. W., Potter, M. C., Lucassen, P. J., and van Praag, H. (2012). Running
throughout middle-age improves memory function, hippocampal neurogenesis
and BDNF levels in female C57BL/6J mice. Dev. Neurobiol. 72, 943–952.
Meeusen, R., and De Meirleir, K. (1995). Exercise and brain neurotransmission.
Sports Med. 20, 160–188. doi: 10.2165/00007256-199520030-00004
Mora-Rodriguez, R., Ortega, J. F., Guio de Prada, V., Fernández-Elías, V. E.,
Hamouti, N., Morales-Palomo, F., et al. (2016). Effects of simultaneous
or sequential weight loss diet and aerobic interval training on metabolic
syndrome. Int. J. Sports Med. 37, 274–281. doi: 10.1055/s-0035-15
Moraska, A., Deak, T., Spencer, R. L., Roth, D., and Fleshner, M. (2000). Treadmill
running produces both positive and negative physiological adaptations in
Sprague-Dawley rats. Am. J. Physiol. Regul. Integr. Comp. Physiol. 279,
Narath, E., Skalicky, M., and Viidik, A. (2001). Voluntary and forced
exercise influence the survival and body composition of ageing male
rats differently. Exp. Gerontol. 36, 1699–1711. doi: 10.1016/s0531-5565(01)
Norris, D. O., and Carr, J. A. (2013). Vertebrate Endocrinology. Waltham, MA:
O’Dell, S. J., Gross, N. B., Fricks, A. N., Casiano, B. D., Nguyen, T. B.,
and Marshall, J. F. (2007). Running wheel exercise enhances recovery from
nigrostriatal dopamine injury without inducing neuroprotection. Neuroscience
144, 1141–1151. doi: 10.1016/j.neuroscience.2006.10.042
Pattengale, P. K., and Holloszy, J. O. (1967). Augmentation of skeletal
muscle myoglobin by a program of treadmill running. Am. J. Physiol. 213,
Saito, T., and Soya, H. (2004). Delineation of responsive AVP-containing neurons
to running stress in the hypothalamus. Am. J. Physiol. Regul. Integr. Comp.
Physiol. 286, R484–R490. doi: 10.1152/ajpregu.00453.2003
Sandrow-Feinberg, H. R., Izzi, J., Shumsky, J. S., Zhukareva, V., and Houle, J. D.
(2009). Forced exercise as a rehabilitation strategy after unilateral cervical
spinal cord contusion injury. J. Neurotrauma 26, 721–731. doi: 10.1089/neu.
Shimizu, H., and Yamanouchi, K. (2011). Acceleration of irregular estrous cycle
in forced running by midbrain raphe lesions in female rats. Neurosci. Lett. 495,
192–195. doi: 10.1016/j.neulet.2011.03.063
Smith, A. D., and Zigmond, M. J. (2003). Can the brain be protected through
exercise? Lessons from an animal model of parkinsonism. Exp. Neurol. 184,
31–39. doi: 10.1016/j.expneurol.2003.08.017
Soya, H., Mukai, A., Deocaris, C. C., Ohiwa, N., Chang, H., Nishijima, T., et al.
(2007). Threshold-like pattern of neuronal activation in the hypothalamus
during treadmill running: establishment of a minimum running stress
(MRS) rat model. Neurosci. Res. 58, 341–348. doi: 10.1016/j.neures.2007.
Stummer, W., Weber, K., Tranmer, B., Baethmann, A., and Kempski, O.
(1994). Reduced mortality and brain damage after locomotor activity in
gerbil forebrain ischemia. Stroke 25, 1862–1869. doi: 10.1161/01.STR.25.
Sutoo, D. E., and Akiyama, K. (1996). The mechanism by which exercise modifies
brain function. Physiol. Behav. 60, 177–181. doi: 10.1016/0031-9384(96)
Tamasy, V., Koranyi, L., and Phelps, C. P. (1981). The role of dopaminergic and
serotonergic mechanisms in the development of swimming ability of young
rats. Dev. Neurosci. 4, 389–400. doi: 10.1159/000112778
Tchernichovski, O., and Benjamini, Y. (1998). The dynamics of long term
exploration in the rat: part II. An analytical model of the kinematic
structure of rat exploratory behavior. Biol. Cybern. 78, 433–440.
Terjung, R. L. (1979). The turnover of cytochrome c in different skeletal-
muscle fibre types of the rat. Biochem. J. 178, 569–574. doi: 10.1042/bj17
Terjung, R. L., and Hood, D. A. (1986). Biochemical adaptations in skeletal
muscle induced by exercise training. ACS Symp. Ser. Am. Chem. Soc. 294, 8–26.
Timofeeva, E., Huang, Q., and Richard, D. (2003). Effects of treadmill
running on brain activation and the corticotropin-releasing hormone
system. Neuroendocrinologyy 77, 388–405. doi: 10.1159/0000
van Praag, H. (2009). Exercise and the brain: something to chew
on. Trends Neurosci. 32, 283–290. doi: 10.1016/j.tins.2008.
van Praag, H., Shubert, T., Zhao, C., and Gage, F. H. (2005). Exercise enhances
learning and hippocampal neurogenesis in aged mice. J. Neurosci. 25,
8680–8685. doi: 10.1523/JNEUROSCI.1731-05.2005
Vivar, C., Potter, M. C., and van Praag, H. (2012). ‘‘All about running:
synaptic plasticity, growth factors and adult hippocampal neurogenesis,’’ in
Neurogenesis and Neural Plasticity, eds C. Belzung and P. Wigmore (Berlin,
Heidelberg: Springer), 189–210.
Wang, Z., Myers, K. G., Guo, Y., Ocampo, M. A., Pang, R. D., Jakowec, M. W.,
et al. (2013). Functional reorganization of motor and limbic circuits after
exercise training in a rat model of bilateral parkinsonism. PLoS One 8:e80058.
Frontiers in Behavioral Neuroscience | www.frontiersin.org 6March 2017 | Volume 11 | Article 42
Toval et al. Habituation Effects in Forced Wheel
World Health Organization. (2010). Global Recommendations
on Physical Activity for Health. Switzerland: World Health
Yanagita, S., Amemiya, S., Suzuki, S., and Kita, I. (2007). Effects of spontaneous
and forced running on activation of hypothalamic corticotropin-releasing
hormone neurons in rats. Life Sci. 80, 356–363. doi: 10.1016/j.lfs.2006.
Zhou, Y., Yuan, Y., Gao, J., Yang, L., Zhang, F., Zhu, G., et al. (2010). An implanted
closed-loop chip system for heart rate control: system design and effects
in conscious rats. J. Biomed. Res. 24, 107–114. doi: 10.1016/S1674-8301(10)
Conﬂict of Interest Statement: The authors declare that the research was
conducted in the absence of any commercial or financial relationships that could
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and Ferran. This is an open-access article distributed under the terms of the Creative
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