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Journal of Exercise Physiologyonline
December 2014
Volume 17 Number 6
Editor-in-Chief
Official Research Journal of
Tommy
the American
Boone, PhD,
Society
MBA
of
Review
Board
Exercise
Physiologists
Todd Astorino, PhD
Julien Baker,
ISSN 1097-9751
PhD
Steve Brock, PhD
Lance Dalleck, PhD
Eric Goulet, PhD
Robert Gotshall, PhD
Alexander Hutchison, PhD
M. Knight-Maloney, PhD
Len Kravitz, PhD
James Laskin, PhD
Yit Aun Lim, PhD
Lonnie Lowery, PhD
Derek Marks, PhD
Cristine Mermier, PhD
Robert Robergs, PhD
Chantal Vella, PhD
Dale Wagner, PhD
Frank Wyatt, PhD
Ben Zhou, PhD
Official Research Journal
of the American Society of
Exercise Physiologists
ISSN 1097-9751
JEPonline
Acute Effect of Weight Training at a Self-Selected
Intensity on Affective Responses in Obese Adolescents
Ragami Chaves Alves1, Jonato Prestes2, Tácito Pessoa de Souza
Junior1, Lucio Follador1, Wendell Arthur Lopes1, Sergio Gregorio da
Silva1
1
Departamento de Educação Física, Universidade Federal do Paraná
(UFPR), Curitiba, Brazil, 2Universidade Católica de Brasília (UCB),
Brasília, Brazil
ABSTRACT
Alves RC, Prestes J, Souza-Junior TP, Follador L, Lopes WA, da
Silva SG. Acute Effect of Weight Training at a Self-Selected Intensity
on Affective Responses in Obese Adolescents. JEPonline 2014;17(6):
66-73. The purpose of this study was to investigate the self-selected
load for weight training and the sensations produced in obese
adolescents. This study consisted of 11 obese adolescent women, 13
to 15 yrs of age with a body mass index 30.0 kg·m-2. Each subject
performed a 1 repetition maximum (1RM) test. The training session
consisted of three exercises: (a) bench press; (b) leg press; and (c)
barbell curl with 3 series of 10 repetitions at a self-selected intensity
with a 1-min interval for rest. At the end of each series, the subjects
reiterated their affective responses at that moment to the researcher.
This procedure was adopted for all of the exercises. ANOVA was
used for the comparison of affective responses between the different
exercises. The findings indicate that the barbell curl presented a
higher unpleasant affective response compared with leg press and
bench press exercises. Weight training exercises at a self-selected
intensity among obese adolescent girls promotes pleasurable
affective responses.
Key Words: Self-Intensity, Weight Training, Affect, Obesity
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INTRODUCTION
It is common knowledge that a sedentary lifestyle can induce several undesirable consequences,
including degenerative chronic and non-communicable diseases such as, for example, obesity. In
1985, obesity was recognized by the World Health Organization (WHO) as a multifactorial disease,
associated with genetic aspects, but mainly is the result of bad eating habits and insufficient levels of
physical activity (15).
Obesity has been treated by researchers as a global epidemic and, therefore, has presented an
exponential growth that has reached alarming levels (17). In Brazil, 15.8% of the population is obese,
and of this percent 44.7% are women (22). Notwithstanding, the (IBGE) (14) reports that in the last
few decades the increase in obesity is also observed in adolescents. In the southern region of the
country, approximately 16.1% of the boys and 17.5% of the girls between the ages of 15 and 19 are
obese.
In addition, due to the early development of hypertension, lipid disorders, and insulin resistance,
these data are of great importance, especially when we consider the study of Troiano and colleagues
(21) that points out that 80% of obese children will remain obese as adults. Consequently, there is an
anticipated reduction in the quality of life, reduction in life expectancy, and an increase in mortality
among the obese adults. This has led the scientific community to focus on seeking effective
strategies in the treatment and prevention of obesity in the adolescent population (1,11).
Interestingly, the prescription of strength training for the adolescents population presents itself as a
promising strategy to promote improvements in lipid profile, cardiovascular fitness, body composition,
and bone mineral density (16,23). Yet, in spite of these benefits, this type of training is not often
practiced among obese adolescents. Part of the reason for this outcome appears to be related to the
intensity initially prescribed (2,8).
Ekkekakis and colleagues (7) reported that the typical intensities used to prescribe aerobic exercise
in obese adults result in unpleasant sensations. This feeling during the exercises has been strongly
associated with high levels of abandonment of the practice (6,7). It is assumed that the displeasure
experienced during the training session creates a negative cognitive association, stimulating a
significant trend towards the discontinuance of the activity. In contrast, Dishman’s (3) work indicates
that when obese individuals use a self-selected intensity during aerobic exercise they experience
pleasant sensations and a greater adherence to exercise programs. Strangely enough, these
pleasant sensations, at self-selected intensity levels, are apparently not observed in weight training in
obese adolescents.
In light of these findings, it seem logical that knowledge of the feelings present in weight training at
self-selected intensities is likely to provide a new strategy for combating obesity in adolescence and
may increase the initial engagement in strength training. Therefore, this study is designed to identify
whether or not the subjects’ self-selected intensity for weight training is effective and whether the
intensity approaches the recommended requirement to promote the subjects’ health and well-being?
METHODS
Subjects
Eleven adolescent girls, aged 13 to 15 yrs with a body mass index (BMI) reference for obesity 30.0
kg.m-2 according to the World Health Organization (24), participated in this study. All of the volunteers
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received individual clarification about the purposes, procedures, possible benefits and risks linked to
the implementation of this study. All subjects signed an informed consent form. The inclusion criteria
were: (a) absence of joint limitations, as well as neurological, cardiovascular or respiratory disorders
that could affect the implementation of the weight training program; (b) self-report of no modification
of habits related to physical exercise in the 6 months prior to the beginning of the assessments; (c) a
medical certificate dated within the 12 months preceding the beginning of assessments noting that
the subject did not present any contraindication to weight training; (d) an index of weekly physical
activity less than 150 min, assessed with the International Activity Questionnaire (IPAQ); and (e) a
BMI 30.0 kg·m-2.
Procedures
Assessment of Sexual Maturation
To determine the subjects’ stage of sexual maturity, the Tanner Scale was used by means of selfassessment. This is a method of recognized validity and reliability (5).
Anthropometric Measurements
The measurement of the body mass (kg) was obtained with a scale (Toledo®, model 2096, Sao
Paulo, Brazil) with a precision of 0.1 kg. The subject was barefoot and wearing light clothes when
asked to stand in the upright position on the center of the balance with her back to the scale in
anatomical position with the body weight equally distributed on both feet while the arms remained
loose along the trunk with the palms facing the thighs (13).
Height, in centimeters, was measured using a stadiometer (Sanny®) fixed to the wall (Standard
model, Sao Bernardo do Campo, Brazil), staggered at 0.1 cm. Height was defined as corresponding
to the distance between the plantar region and the vertex. The subject remained barefoot and
anatomically positioned on the stadiometer, which formed an angle of 90° with the vertical edge of the
stadiometer that allowed for distributing the weight on both feet while the arms remained freely loose
along the trunk with palms facing the thighs. From the ratio of these two measures, the BMI was
determined in kg·m-2.
1 Repetition Maximum (1RM) Protocol
The maximum muscle strength was determined when the volunteers successfully performed the
movement with the weight only once. If there was enough force to result in a movement, the load was
increased and another attempt was then performed after 3 to 5 min of rest (10). Before the tests of
1RM, the subjects went through a period of familiarization that included two sessions, in which the
exercises prescribed were demonstrated with verbal instructions and concurrent execution. In these
sessions, the subjects performed two series of 10 repetitions with a very mild load for the bench
press, leg press, and biceps curl with the aim of teaching the proper implementation and control of
the movement. After this period, 1RM for each of the three exercises was determined. The subjects
were verbally encouraged during the attempts. Only those repetitions that completed the full cycle of
movement were valid.
Self-Selected Load Protocol
In training with a self-selected load, the subjects were instructed to choose a load with which they
were able to perform 3 sets of 10 repetitions using the following instruction (18): "How much weight
would you select in this exercise to perform 1 series of 10 repetitions?" They were given three
opportunities to select the appropriate weight (i.e., if the initial selection was too light or heavy). No
information was provided regarding the selection of the weight. Once the appropriate weight was
selected, each subject was carefully instructed to carry out a series of 10 repetitions with the
complete motion and a speed of 2:2 (concentric and eccentric contractions).
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Feeling Scale - Affect
The Feeling Scale (12) was used as a measure of the affective dimension of pleasure and
displeasure. The Feeling Scale is an 11-point single item bipolar measure, ranging from +5 (“very
good”) to -5 (“very bad”), with anchors at all odd integers and at the zero point (neutral). The subjects
were asked to rate how they felt at the finish of each set for every exercise.
Statistical Analyses
The collected data were tabulated and stored in a database developed in the program Microsoft
Office Access 2003. All data were analyzed using the statistical software Statistical Package for the
Social Sciences (SPSS, version 18.0) for Windows, with a significance level set at P≤0.05 for all
analyses. First, the data analysis employed descriptive statistics with measures of central tendency
and variability (mean and standard deviation) for the characterization of the subjects. To verify the
normality of the data set, the Kolmogorov Smirnov test was used. Analysis of variance (ANOVA) was
conducted for the comparison of affective responses between the different exercises.
RESULTS
General characteristics and anthropometrics related to the subjects, as well as the body mass, height,
and BMI are summarized in Table 1 in the form of mean (M) and standard deviation (±SD).
Table 1. Sample Characterization.
Parameters
(N = 11)
M ± SD
Age (yrs)
13.7 ± 2.1
Body Mass (kg)
75.2 ± 5.8
Height (cm)
165 ± 1.1
BMI (kg·m-2)
32 ± 3.2
Tanner Breasts
IV+
Tanner Pubic Hair
IV+
+Values
were expressed as median; BMI: body mass index.
Table 2 presents the values of affective responses for each exercise. The ANOVA two factor
repeated measures test revealed a significant difference (F (6.8) = 23,752; P<0.001) between the
exercises. The analysis revealed that the barbell curl presented an affective response that was more
unpleasant when compared with the leg press and bench press exercises.
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Table 2. 1RM (kg), Self-Selected Loads (kg) and Affective Responses.
Exercises
1RM
(M ± SD)
Self-Selected Loads
(M ± SD)
Affect
(M ± SD)
Bench Press
29 ± 3.4
14.4 ± 3.9
0.5 ± 1.8
175 ± 28
76.8 ± 20
1.6 ± 1.4
18 ± 2.2
12.3 ± 2.7
0.4 ± 1.8*
Leg Press
Barbell Curl
*Significant difference (P<0.01)
DISCUSSION
The purpose of this study was to investigate the self-selected load during strength training and the
feeling (pleasure/displeasure) generated. The findings indicate that the self-selected load for the
bench press, leg press, and barbell curl corresponded to 48%, 43% and 66% of 1RM, respectively.
The American College of Sports Medicine guidelines (1) recommends the practice of strength training
at an intensity of 40 to 50% of 1RM for beginners and sedentary subjects in order to increase
muscular strength among other benefits. However, the level of evidence for this recommendation is a
subject of controversy (4). Thus, a more reliable recommendation to promote health benefits for
beginners (1) is probably between 60 to 70% of 1RM intensity.
Given this perspective, the self-selected loads for the bench press and leg press exercises do not
meet this recommendation. This demonstrates that adolescents without prior experience are not able
to self-select the intensity needed to promote health benefits according to the ACSM criteria during
the initial training phase. Elsangedy et al. (9) conducted a study with a similar design in previously
active elderly individuals and observed similar results for the bench press, leg extension, leg press,
dumbbell side lateral rise, and lying barbell triceps extension. They reported percentages of selfselected loads between 43% and 51.7% of 1RM.
In accordance with hedonic theories, human beings unconsciously seek to experience pleasant
sensations in all situations. This fact could partially explain some of the results found in this study
(20). Pleasurable feelings are derived from the self-selected loads, while higher intensities could
induce unpleasant feelings due to the increase in metabolic stress (7,8). This way, more intense
loads, which are ideal for the promotion of health becomes more difficult to self-select. However, we
observed a percentage of 66% of 1RM for the barbell curl in the present study, which is in
accordance with the recommendations of the ACSM (1), and still produced a feeling of pleasure.
Perhaps, the fact that the adolescents had autonomy on the prescription of intensity may have had
some influence (i.e., encouraging the self-selection of a greater percentage while preserving a
pleasurable sensation). The theory of self-determination supports this assumption and, therefore,
subjects in control of the situation have pleasant sensations, thus partially explaining the results of the
present study (19).
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Comparisons between bench press and leg press exercises showed no significant differences in the
feeling of pleasure. However, the barbell curl showed a pleasurable feeling that was significantly
lower compared to both the bench press and the leg press. Some hypotheses have been suggested
in an attempt to explain this finding. We assumed that the bench press, an exercise for the upper
limbs, and the first in the order of execution, had not resulted in lower levels of pleasant feelings when
compared with the other exercises because the subjects were not experiencing the effect of
accumulated muscle fatigue. For the leg press, the same principle is applied, because the exercise
works a different group of muscles (i.e., lower limbs). However, this approach does not apply to the
barbell curl, an exercise performed with the upper limbs. We suggest that the poor fitness levels of
the subjects impaired the upper limbs recovery causing an accumulated fatigue that contributed to the
decreased feeling of pleasure.
Weight training is clearly a more complex exercise in comparison to aerobic exercises due to its wide
range of specific muscular actions. Quite possibly, this fact was reflected in the results found in the
present study. Therefore, further studies are required to reach a consensus about the self-selected
loads and the sensations produced in different weight training exercises.
CONCLUSIONS
Based on the results found in the present research, it is concluded that weight training at a selfselected intensity for adolescent girls with obesity promotes pleasurable affective responses. From
the assumptions stipulated by the theories and studies with aerobic exercises, it is believed that this
intensity possibly promotes a greater adherence to a weight training regimen. However, further
studies should be conducted with different methodologies in order to fill the gaps that still exist in the
literature on this topic.
Address for correspondence: Ragami Chaves Alves, MSc, Federal University Department,
Curitiba, Paraná, Brazil, zip-code: 80020-010, Email: [email protected]
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