Table 3.

Barriers and facilitators identified in the selected systematic reviews.

References	Barriers	Facilitators
Al-Hazzaa (30)	No appropriate place for PA; lack of time, facilities, and resources	Weight loss
Allender et al. (31)	Negative experiences at school; peer pressure; identity conflict; PE uniforms; boys' dominance in class; competitive classes; lack of teachers support; competitive sports; highly structured activities	Body shape; weight management; beauty; new social networks; family, peer and school support; a safe environment; experimentation; unusual activities
Allison et al. (32)	Family responsibilities; lack of skills; preference for other activities; lack of time; the cost of activities; lack of support from PE teachers	Being healthy; losing weight; looking better; enjoyment atmosphere of sessions; the importance of the coach in enjoyment, motivation, attendance and participatory style of coaching; experimentation of new modalities; opportunity to engage in girls-only activities; provision of clubs/sports; consultation with girls about sports preferences and formats of delivery
Corr et al. (16)	Gender bias in sport: Body image/body-centered issues (low perceived competence, high weight status, biological changes during puberty); societal pressure (bullying, stereotypes of femininity, PA contradicts the image of femininity); peer and teachers' feedback (PE teacher not supportive) Motivation and perceived competence: Low perceived skill (ability levels and competition); PA opportunities (lack of variety and emphasis on skill) Competing priorities during adolescence: Schoolwork and home responsibilities (lack of time due to increased workloads in school, the pressure of parents to perform well at school, increased responsibilities at home); parental expectations (encouragement for different subjects, focus on achieving high grades, working part-time); changes in leisure activities (preference for other leisure activities) Meeting societal expectations: Peer influence (friends do not participate in PA, fear of ridicule from friends); adult influence (lack of support and encouragement from teachers or parents); community influence (rural settings are limited in the choice of activities, high costs of membership in clubs, competition)	Gender bias in sport: Peer and teachers' feedback (encouragement from teachers for active girls with high skill levels and those who perceive competence) Motivation and perceived competence: Perceived skills (high ability levels and competition with friends); PA opportunities (single-sex classes, classes focused on fun and involvement) Competing priorities during adolescence: Changes in leisure activities (increased opportunities with older ages) Meeting societal expectations: Peer influence (friends participate in PA); adult influence (perceived support and encouragement from teachers or parents); community influence (variety of activities in urban settings)
Martins et al. (33)	PA attitude: Competition climate; negative experiences in PE classes; the pressure of winning and failing in front of their peers and peers' negative reactions; not feeling comfortable, absence of fun, and learning opportunities Motivation: Lack of motivation and enthusiasm Fun: Lack of fun Perception of competence: low perception of competence Body image and exposure concerns: Feeling discomfort in front of others and physical appearance (sportswear, sweating, weight) Perception of femininity and social norms: Femininity is not compatible with PA Time and competing for leisure activities of PA: Lack of time; preference for other leisure activities Influence of friends, family, and significant others: Preference for other activities from friends; negative experiences with friends; lack of support of friends; physically inactive family members; lack of encouragement, financial support, and transportation from family; too much pressure to improve academic performance; sessions focused on competition and not inclusion, not fun-oriented, high levels of intensity; lack of encouragement from teachers; curriculum focused on sports perceived as masculine Environmental opportunities: Lack of offers of PA programs in school and community; difficulty	PA attitude: Active girls associate with health benefits, physical appearance, social interactions, positive experiences, fun, diversity of activities Fun: Having fun Perception of competence: High levels of perception of competence Body image and exposure concerns: Good appearance and adequate weight Perception of femininity and social norms: Media in changed social norms Time and competing leisure activities of PA: PA opportunities during school time Influence of friends, family, and significant others: Presence and practice of PA with friends; friends support; encouragement, transportation, financial support, Support of PA from family; PA with their family members; participation in sports clubs as a child; encouragement, support, help in improvement in activities and explanation of PA benefits from PE teachers; the presence of adults close to the PA locations for security reasons Environmental opportunities: Opportunities at school (PE, school sports, break time, field trips); neighborhood facilities, low cost of PA programs; the existence of facilities and equipment in school, at home and in the neighborhood
	accessing PA programs (costs, time, schedule, distance from home, lack of transportation, and low security); lack of infrastructures Life transition periods: Adolescents with low PA levels in the transition from primary to high school, due to increased workload, lack of motivation, fewer opportunities, focus on competition, and giving more importance to other activities
Rees et al. (34)	PA and school: PE environment and rules PA and family and friends: Parental constraints (safety, monitoring leisure time to ensure that have time to do homework and domestic chores, disapproval of exercise) Peer constraints: Prejudiced attitudes of boys PA and the self: Feelings of discomfort during PA; self-consciousness about bodies/appearance PA and practical and material resources: Provision of highly structured activities	PA and school: Consultation in choice of activities; mixed-sex activities and the chance to participate in activities traditionally seen as being for young men PA and family and friends: Parental support (encouragement and material resources); chance to make new friends Peer constraints: Social support from friends PA and the self: Help with losing weight; articles promoting PA in magazines
Standiford (35)	Perceptual influences: Appearance concerns (maintaining a feminine physical appearance); personal barriers to PA (preference for sedentary activities, lack of time, lack of motivation, perception PA is not fun, lack of money for sports, and transportation to gyms); body image (discomfort at doing PA in front of others in PE classes/gym, being objectified by boys in PE classes or active play, being bullied or harassed due to the body size and shape) Interpersonal influences: Ability comparison and competition (poor performance, conflict with classmates, fear of criticism in PA, lack of PA choices in PE for those who are less physically fit); family, peer, and teachers influence (safety concerns, belief that PA is not proper for girls, time constraints; intimidation, bullying, and exclusion in PE classes); contending with boys Situational influences: Accessibility and availability (preferred sport not available, community sports clubs expensive, school sports programs have outdated equipment and inconvenient hours, distance from recreational centers for rural girls); PA and gender role (social pressure of appearance and behavior, fewer sports opportunities than boys); safety concerns (perception of dangerous or crime in the environment of recreational centers and neighborhood outdoor areas)	Perceptual influences: Perceived benefits of PA (positive beliefs about engaging in PA: stay in shape, looking good, feel better, relaxed and energetic, health risk reduction, more fun than sedentary pursuits, a good time to be alone, escape the pressure, and stresses of everyday life); PA enjoyment (feel of enjoyment, being able to choose activities without control from others); favorite PA (possibility for choosing preferred activities and its delivery) Interpersonal influences: Ability comparison and competition (good performance); family, peer, and teachers influence (rides to the gym, monetary support for sports; opportunity to socialize). Situational influences: Accessibility and availability (geographical proximity and social and financial feasibility of PA programs)
Stankov et al. (36)	Environment: Regulatory environment (inappropriate teaching practices, having to wear a uniform or follow a dress code during PE classes, promotion of sedentary activities); built environment (lack of privacy in changing rooms, lack of resources, lack of neighborhood safety); inhibitory social norms (the perception that PA is not culturally valued); physical environment (weather conditions) Interpersonal: Victimization (verbal and physical bullying, social exclusion, and stereotyping by peers); nature of household (noisy and cramped household); lack of social support (peers and family) Individual: Negative body image (perception of not looking good as others during PE classes); perceived victimization (perception of being verbally bullied by peers during PE classes); perceived inferiority in social settings (perception of being negatively judged by others during PE classes, perception of reduced ability relative to others, dislike of being visible in PE classes); competing demands on time	NR
	(obligations to family and friends, school and homework commitments, length of travel to and from school for the ones in rural areas); lack of motivation (persistent failure during PA, lack of motivation by laziness); physical factors (physical discomforts, too out of shape, fatigue after the day and exercise, perceived beauty cost); capacity (lack of competence in setting goals, low self-efficacy or confidence in the ability to seek support given problems with transportation); lack of knowledge (false beliefs about PA, the perception that PA is of little benefit)

NR, not reported; PA, physical activity; PE, physical education.