By: John, Adam, and Andrew

Purpose  To explore the effect of free weights and elastic tubing resistance training on physical self-perception in adolescents.  Hypotheses: Adolescents in both resistance training groups would significantly increase their physical self-perception over the study period and that these changes would be associated with reductions in body fat and increases in muscular strength. Changes in physical self-perception would be larger among those in the free-weight tubing group.

Sampling  Participants Volunteer students in 9 th and 10 th grade No prior or current resistance training No medical conditions or physical injuries 108 students; 56 boys and 52 girls  Assignment Random assignment into 1 of 3 groups Stratified by gender and year group to reach equal numbers in each group

Groups  1 free weight resistance training group 22 boys and 15 girls  1 elastic tubing resistance training group 20 boys and 21 girls  1 control group 14 boys and 16 girls

Procedure  All groups were told not to change their diet  Control group was told not to do any resistance training  All 3 groups were told to keep the same level of physical activity as before  Participated in progressive resistance training programs Twice weekly 8 weeks long

Procedure  Participants completed two sets of 8-12 repetitions for 10 exercises repetitions for weeks repetitions for weeks second rests in between each set Entire session lasted minutes

Procedure  Participants in free weight group used dumbbells, barbells, and benches  Participants in elastic tubing group used the elastic tubing resistance training device known as the Gymstick  All participants used Borg’s rating of perceived exertion to judge their weight load (target load ranged from hard to very hard)  Asked to record all aspects of their sessions including volume and perceived exertion.

Procedure  Measurements were completed at the study school using the same instruments at each time point. Measured muscular strength using a progressive repetition maximal lift in bench press and incline seated leg press Measured height/weight to the nearest.1 kg/cm Measured body composition using a bioelectrical impedance analyzer ○ Students were asked to maintain normal hydration patterns  Participants also completed questionnaires before physical assessments to prevent the results from influencing their answers (pre and post test)

Procedure  Completed the children’s physical self-perception profile Contains five subscales: Sport competence, physical condition, strength, body attractiveness and overall physical self-worth ○ Rated components of subcategories on a scale of 1-4  Also completed a resistance training self-efficacy and outcome expectancy survey Answered questions such as: “If I participate in regular resistance training then it will help me increase my muscular strength” Used the Likert scale 1-5 to assess their beliefs and self-efficacy regarding resistance training at baseline and post test ○ 1 = strongly disagree and 5 = strongly agree

Results  Physical self-perception did not change significantly among boys  Physical self-perception only changed significantly for girls in one group Free weight resistance training group Increase in body attractiveness  Relationship between reductions in body fat and physical self-worth and body attractiveness in boys and girls, respectively, was present, but not statistically significant.

Variables  Independent Resistance training ○ Free weights or elastic tubing  Dependent Physical self-perception in adolescents  Relationship being examined The effects of free weights and elastic tubing resistance training on physical self-perception in adolescents.

Hypotheses Adolescents in both resistance training groups would significantly increase their physical self-perception over the study period and that these changes would be associated with reductions in body fat and increases in muscular strength. ○ The results only slightly supported this; further study would be needed to fully support this hypothesis Changes in physical self-perception would be larger among those in the free-weight tubing group. ○ Supported- The one group that had significant changes belonged to the free weight group

External Validity  Generalizing to all adolescents Sampling group was ages and only drawn from one school in Australia.  Possible Threats Could cultural differences account for either increases or decreases in physical self-perception in adolescents in different countries? ○ Countries like the U.S. place a lot of emphasis on body image

External Validity  Threats Cont. Could the fact that the participants were all volunteers influence the results? ○ The researchers admitted that those who would most benefit from the study were less likely to volunteer. Could the age of participants (14-15) misrepresent the label “adolescents”? Would the results differ if the study included 16 or 17 year olds? ○ Adolescents at younger ages are usually not as confident; this could skew results.

Construct Validity  Study Design R O X1 O R O X2 O R O O  Independent Variable- Resistance training They did a good job creating two levels of their construct Also altered their routine halfway through the treatment period which further decreases likelihood of mono-operation bias Interaction of different treatments and interaction of testing and treatment both do not apply

Construct Validity  Confounding constructs and levels Not likely to be a threat, because both groups were aiming for roughly 80% exertion rate.  Restricted generalizability across constructs Treatment was done during their lunch time Could skipping lunch alter the results in one way or another? ○ Skipping meals would reduce overall caloric intake, potentially reducing body fat more than the weight training programs would alone

Construct Validity  Dependent Variable- physical self perception Measured construct in two different ways which strengthens their results Tested physical self-perception before testing physical strength and body fat, eliminating the threat of lack of progress negatively skewing their self-perception scores. Performed both a pre and post test

Construct Validity  Possible threats No reasonable threats to the construct validity aside from social threats ○ Participants were encouraged to maintain the same level of physical activity and caloric intake during the study as they had before ○ However, they were not required to record their daily food intake or physical activity The participants might decide to do extra work in order to better achieve the “desired” result. Or, is it possible that the participants were exercising more or eating less subconsciously, since they weren’t required to keep track of their progress? -Either one of these potential situations would skew the results

Internal Validity  The study was random assignment which automatically eliminates single-group and multiple-group threats  Social Interaction Threats Resentful demoralization ○ If the elastic tubing resistance group grows resentful of the free-weight training group it could impact their results. ○ The elastic tubing group could get bored with their treatment over time, affecting the amount of effort put forth

Internal Validity  Compensatory rivalry  The two treatment groups could become very competitive with each other, especially being high school students  However, despite these potential threats, it is unlikely that the internal validity would be compromised.