Exercising for food : bringing the laboratory closer to nature

Fonseca, I; Passos, R; Araujo, F; Lima, M; Lacerada, D; Pires, W; Soares, D; Young, RJ; Rodrigues, L

Abstract

Traditionally, exercise physiology experiments have borne little
resemblance to how animals express physical activity in the wild. In
this experiment, 15 adult male rats were divided into three equalsized
groups: exercise contingent (CON), non-exercise contingent
(NON) and sedentary (SED). The CON group was placed in a cage
with a running wheel, where the acquisition of food was contingent
upon the distance required to run. Every 3 days the distance required
to run to maintain food intake at free feeding levels was increased by
90% in comparison to the previous 3 days. The NON group was
housed identically to the CON group, but food acquisition was not
dependent upon running in the wheel. Finally, the SED group was
kept in small cages with no opportunity to perform exercise. A twoway
ANOVA with repeated measures was used to determine
significant differences in responses between the experimental phases
and treatment groups, and ANCOVA was used to analyse growth and
tissue mass variables with body length and body mass used
separately as covariates. A post hoc Tukey’s test was used to
indicate significant differences. A Pearson’s correlation was used to
test the relationship between the distance travelled by the animal and
the distance/food ratio. The level of significance was set at P<0.05
for all tests. The CON group showed the hypothesized correlation
between distance required to run to obtain food and the mean
distance travelled (P<0.001), during 45 days in the contingency
phase. This group showed a decrease in body mass, rather than an
increase as shown by NON and SED groups. The CON group had a
significantly lower body temperature (P<0.05) and adiposity (P<0.05)
when compared with the other two groups for the same body size.
The present experimental model based on animals choosing the
characteristics of their physical exercise to acquire food (i.e. distance
travelled, speed and duration) clearly induced physiological effects
(body characteristics and internal temperature), which are useful for
investigating relevant topics in exercise physiology such as the link
between exercise, food and body mass.

• Journal Article Type: Article
• Acceptance Date: Jun 20, 2014
• Online Publication Date: Sep 17, 2014
• Publication Date: Sep 17, 2014
• Deposit Date: Jan 20, 2015
• Journal: The Journal of Experimental Biology (JEB)
• Print ISSN: 0022-0949
• Electronic ISSN: 1477-9145
• Publisher: Company of Biologists
• Peer Reviewed: Peer Reviewed
• Volume: 217
• Pages: 3274-3281
• DOI: https://doi.org/10.1242/jeb.108191
• Publisher URL: http://dx.doi.org/10.1242/jeb.108191
• Related Public URLs: http://jeb.biologists.org/
• Additional Information: Funders : CNPq;Coordenação de Aperfeiçoamento de Pessoal de Nivel Superior;Fundação de Amparo à Pesquisa do estado de Minas Gerais (FAPEMIG); Grant Number: BPD-00180-12