Obesity is a growing health problem globally (Swinburn et al., 2011). It is an established
risk factor for chronic metabolic and cardiovascular diseases (Kelsey, Zaepfel, Bjornstad,
& Nadeau, 2014; Washington, 2008). In overweight and obese children and adolescents
(5–17-year olds; further referred to as youngsters), not only metabolic health, but
also psychological well-being is at risk (Cooke, Butterly, Mackreth, Carroll, & Gately,
2000; Kelsey, Zaepfel, Bjornstad, & Nadeau, 2014; Van der Baan-Slootweg et al., 2010).
Besides overeating and genetic susceptibility, an insufficient level of physical activity
is one of the main contributors to childhood overweight and obesity (Kremers, Visscher,
Seidell, van Mechelen, & Brug, 2005), and the target of many obesity reduction programmes
(Lee, Shiroma, & Lobelo, 2012). Recent meta-analyses, however, show no effects of
present physical activity programmes on body weight or body mass index (BMI, Guerra,
Nobre, Silveira, & Taddei, 2013; Guerra, Nobre, da Silveira, & Taddei, 2014; Harris,
Kuramotoda, Schulzer, & Retallack, 2009), blood pressure (Guerra et al., 2013) or
physical activity level (Metcalf, Henley, & Wilkin, 2013). In this editorial, we highlight
the putative physiological and psychological benefits of resistance exercise training
for obese youngsters as a relatively new direction in psychology and health.
The focus of a new programme
In our view, a long-term effective physical activity programme for overweight youngsters
can be accomplished by combining biological and psychological knowledge. We think
that current exercise programmes for overweight and obese youngsters are based on
incorrect assumptions as they tend to focus predominantly on aerobic exercises and
weight loss (Faigenbaum, 2007). We hypothesise that a physical activity programme
should initially aim for obtaining a healthier body composition rather than weight
loss, i.e. a relatively higher fat-free mass and a relatively lower fat mass. Improving
the fat-free mass/fat mass ratio may increase energy metabolism and decrease the risk
of chronic diseases (Dixon, 2010).
Overweight youngsters can often not compete with normal weight youngsters when it
comes to aerobic exercises (Faigenbaum et al., 2009). Instead, resistance exercises
might be easier for overweight youngsters, and therefore easier to comply with (Colella,
Morano, Robazza, & Bortoli, 2009; Riddiford-Harland, Steele, & Baur, 2006). Additionally,
when they participate in those resistance exercises, it might have a positive effect
on their muscle (fat-free) mass (Lau, Yu, Lee, & Sung, 2004; Schranz, Tomkinson, Parletta,
Petkov, & Olds, 2013; Yu et al., 2008). We argue that the focus of physical activity
should be less on what these youngsters have to do, and more on what they like to
do. This mindset might lead to long-term compliance in physical activity behaviour
(Fishbein & Ajzen, 2010; Vansteenkiste, Soenens, & Lens, 2007). In order to become
healthier in the long term, we suggest obesity reduction programmes in overweight
youngsters that focus more on resistance exercises.
Resistance training as innovation in practice
Resistance exercises, whereby an individual is working against a wide range of resistive
loads to enhance health (Lloyd et al., 2013), are not a new idea. In the past, it
has been suggested that resistance exercises are harmful for youngsters, particularly
during growth (i.e. growth plate injuries or stunted growth). However, more recent
data indicate that this is a persistent misperception devoid of any evidence (Barbieri
& Zaccagni, 2013; Benjamin & Glow, 2003; Benson, Torode, & Fiatarone Singh, 2008;
Faigenbaum, 2007; Faigenbaum & Myer, 2010; Lloyd et al., 2013). As long as resistance
exercises are performed under qualified supervision, they can even prevent injuries
and cause a rapid rehabilitation from injuries (Lloyd et al., 2013; Sothern et al.,
2000). In fact, since 2008, public health agencies included resistance training as
part of their physical activity guidelines for youngsters (Department of Health, Physical
Activity, Health Improvement & Protection, 2011; McCambridge & Stricker, 2008; United
States Department of Health & Human Services, 2008; World Health Organization, 2010).
Earlier studies have already suggested the use of resistance exercises in (overweight)
youth (see, e.g. Faigenbaum, 2007; McGuigan, Tatasciore, Newton, & Pettigrew, 2009;
Sothern et al., 2000). However, the link between the focus on the biological strengths
and the positive psychological consequences that it may yield is still undervalued.
From a biological perspective, there is a consensus that most youngsters and adults
with overweight do not only have an absolute higher fat mass but also an absolute
higher fat-free mass than their lean counterparts (Westerterp, Donkers, Fredrix, &
Boekhoudt, 1995). Consequently, they have more muscle mass, making them stronger in
absolute sense, and less limited in the performance of resistance exercises. Empirical
evidence shows that overweight youngsters perform even better on resistance-based
exercises than their normal weight peers (Colella, Morano, Robazza, & Bortoli, 2009;
Riddiford-Harland, Steele, & Baur, 2006). Furthermore, by performing resistance exercises
one’s fat-free mass increases, resulting in long-term positive effects on metabolic
and cardiovascular health (Alberga, Farnesi, Lafleche, Legault, & Komorowski, 2013;
Lloyd et al., 2013).
From a psychological point of view, interventions focusing on behaviour change are
most effective when perceived behavioural control for performing the new behaviour
is high, and the new behaviour has positive outcome expectations (e.g. more fun) and
is more intrinsically rewarding (Ekkekakis, Lind, & Joens-Matre, 2006; Fishbein &
Ajzen, 2010; Fortier, Williams, Sweet, & Patrick, 2009; Rhodes, Fiala, & Conner, 2009;
Ryan & Deci, 2002). Compared to normal weight youngsters, overweight youngsters are
less capable of performing at a desired or comparable level in aerobic exercises (D’Hond,
Deforche, De Bourdeaudhuij, & Lenoir, 2008; Faigenbaum et al., 2009). These negative
experiences may result in disinterest and a loss of motivation, causing a vicious
cycle: the loss of motivation causes individuals to disengage from physical activity.
This lack of physical activity causes an increase in weight, which in turn may result
in even lower levels of physical activity. We expect that overweight youngsters will
notice that resistance exercises are easier than aerobic exercises and that their
performance will be better than the performance of their normal weight counterparts.
As a consequence, their enhanced feelings of competence may induce an increase of
autonomous motivation for physical activity, which is required for sustained behaviour
change (Silva et al., 2011). We therefore expect that in the long term, these overweight
youngsters will feel fitter, stronger, more confident, and they will perceive physical
activity as more positive. The hypothesised psychological gains (e.g. enhanced feelings
of competence and perceived behavioural control) are lacking in programmes focusing
on aerobic exercises (Ryan & Deci, 2002).
Current evidence for psychological strengths
Empirical evidence exists for the biological benefits of resistance training (see,
e.g. Lloyd et al., 2013), but we have limited knowledge about the psychological benefits
of resistance training. In a review by Schranz, Tomkinson, and Olds (2013a) on the
effects of resistance training for overweight youngsters, empirical support for large
positive effects on muscle strength and small positive effects on body composition
were reported. However, the effects of resistance training on psychosocial outcomes
remained unclear because of the limited number of studies available. In a later Randomized
Controlled Trial (RCT), Schranz and colleagues (2013) found large increases in strength,
perceived behavioural control, confidence and self-esteem during and immediately after
a six months resistance training programme compared to a no intervention control group.
However, six months after the intervention had ceased, the adolescents’ outcomes had
returned to baseline levels. Velez, Golem, and Arent (2010) reported improved competences
and self-worth in both normal and overweight adolescents after 12-weeks of resistance
training, compared to a regular physical activity education training. Lubans, Aguiar,
and Callister (2010) found a significant improvement in perceived body attractiveness
in secondary school girls after resistance training and compared to a control group
maintaining their normal physical activity and nutrition behaviour. Yu et al. (2008)
found that in a strength exercise group of obese children (but not in a diet-only
group), the physical self-concept in endurance improved. Lau et al. (2004) found non-significant
improvement in obese adolescents’ anxiety levels with no additional effect of strength
training. In a qualitative study, Pescud, Pettigrew, McGuigan, and Newton (2010) reported
pleasant social interactions, improved confidence and self-esteem, and ongoing parental
support as factors for continuation in a resistance programme for the children.
Research Agenda
To develop a long-term effective resistance-based physical activity programme, there
are still several issues that need to be answered. First, the right methods should
be identified to convince parents of the benefits of resistance exercises. Youngsters
often do not engage in resistance exercises, because parents lack knowledge about
resistance training. This was shown in a recent cross-sectional study among 314 parents
of 12- to 15-year olds, where 93 parents (29.6%) stated that they would not allow
their child to perform resistance exercises (Ten Hoor et al., submitted). Almost half
of them (n = 42) indicated the child being too young, or considered resistance exercises
not healthy during growth. Interestingly, Pescud, Pettigrew, McGuigan, and Newton
(2010) describe that parents can learn to accept positive changes in body composition
as desirable outcomes of strength training instead of weight loss.
Second, to make programmes sustainable, youngsters need to be guided from supervised
settings to non-controlled settings where they remain physically active. Adding motivational
techniques such as motivational interviewing (Naar-King & Suarez, 2011; Ryan & Deci,
2002) might be helpful to strengthen the motivation for change and enhance behavioural
maintenance by focusing on what youngsters like to do. Motivational interviewing is
a collaborative, goal-oriented style of communication with particular attention to
the language of change. It is designed to strengthen personal motivation for and commitment
to a specific goal by eliciting and exploring the person’s own reasons for change
within an atmosphere of acceptance and compassion (Miller & Rollnick, 2013).
Randomised controlled trials should evaluate the immediate and long-term effectiveness
of a combined resistance and motivational intervention.
Third, further research is required on how possible programme characteristics (e.g.
intensities, quantities, form of exercise, feedback mechanisms) can be tailored to
the individual (e.g. for the same exercise, an overweight adolescent lifts a heavier
weight than a lean adolescent) or group level (e.g. girls may prefer other resistance
exercises than boys, Biddle, Braithwaite, & Pearson, 2014). For example, it will be
a challenge to develop resistance exercises that are attractive to adolescent girls.
Therefore, the development of an adequate programme of resistance exercises requires
active participation of all stakeholders (including the target population, sports
clubs, and physical education teachers).
A fourth research topic is the under-investigated relation between social comparison
and self-determination. Given that overweight youngsters are better in resistance
exercises than normal weight youngsters, applying social comparison theory (Lemaine,
1974; Suls, Martin, & Wheeler, 2002; van Knippenberg, Wilke, & de Vries, 1981) would
suggest having overweight and normal weight youngsters exercising together. Overweight
youngsters may find out that they perform better in the domain of resistance exercises
(contrary to the domain of aerobic exercises) which, in time, is hypothesised to improve
their self-worth. Some authors (e.g. Ames & Archer, 1988) have suggested that stimulating
social comparison may have detrimental effects on autonomous motivation. However,
O’Keefe, Ben-Eliyahu, and Linnenbrink-Garcia (2013) suggest that social comparison
is part of typical classroom settings and therefore unavoidable. Note that we do not
suggest promoting ‘outperforming others’, as this might relate to more controlled
types of motivation, but a positive comparison with others for youngsters who are
used to only experiencing negative comparisons. Moreover, Senko, Hulleman, and Harackiewicz
(2011) argued that normative-based performance goals often facilitate classroom achievement.
Standage, Duda, and Ntoumanis (2003) found that perceptions of competence and relatedness
are more predictive of self-determined motivation than autonomy, but also that normative
feedback that is repeatedly negative will lead to a-motivation. We think that, next
to promoting autonomy (e.g. by giving youngsters choices; Deci & Ryan, 2000), positive
social experiences of overweight youngsters with resistance exercises may increase
their perceptions of competence, their self-worth, and in time, their intrinsic motivation
for exercise. Moreover, having youngsters compete as teams in multi-component exercises,
might encourage interpersonal appreciation of various skills, e.g. speed Vs strength.
This is a topic for further research. The relation between social comparison theory
and self-determination theory has rarely been studied empirically (Neighbors & Knee,
2003).
Conclusion
We have argued that new physical activity directions for overweight and obese youngsters
might benefit by a stronger emphasis on resistance exercises, whereas a motivational
intervention might stimulate them to engage in these exercises. When it comes to overweight
and obese youngsters, based on the currently available evidence, we suggest to stop
emphasising their overweight, stop pushing them for weight loss, and to start focusing
more on resistance exercises. In our view, it is time to start concentrating on their
biological strengths and using psychological principles and techniques to make youngsters
aware of these strengths. Only then long-term behaviour changes and long-term health
benefits may be achieved. To make overweight and obese youngsters healthier, stronger,
more confident (and feeling better in general), resistance exercise may be the fruitful
way to go.