Effects of plyometric-based high-intensity interval training on muscle-to-fat ratio in children: protocol for a randomized controlled trial in primary school settings.

Friends occupy a central position in the social lives of youth. Friends make important contributions to academic (e.g., school achievement; ) and psychosocial (e.g., adjustment difficulties and prosociality; ) development, so it matters who youth select as friends. As is the case for adults, children and adolescents prefer the company of similar peers (e.g., ). Much of this similarity comes from selecting friends who share resemblances—demographic and behavioral similarity are particularly important (). Our focus here is on two related forms of demographic similarity: Ethnic background and language spoken at home. White youth, African American youth, and Asian youth all tend to select same-race peers rather than cross-race peers as best friends (e.g., ; ). Ethnicity is central to identity for youth in many of these groups. The link is less clear for Hispanics, in large part because language and ethnicity make important, but often confounded, contributions to Hispanic identity (). Studies of ethnic background friend similarity, however, rarely delineate youth of Hispanic descent. Equally rare are studies of friend heritage language similarity. Hispanic youth pose a special case, because for some, ethnic background cannot be separated from language spoken at home. To disentangle ethnic background similarity from home language similarity, the present study examines the contributions of each to friend selection among two diverse samples of Florida (USA) primary and middle school students. According to the similarity-attraction model (), similarity underlies liking and promotes interpersonal attraction which, in turn, leads to friendship formation (see ). We know that youth who share similar behavioral and demographic traits are more likely to become friends than those who are not similar, and that the more similar they are, the more stable their friendship (). The two-stage model of interpersonal attraction holds that youth first identify those who share similarities on visible demographic characteristics and then select--from among this constrained pool--others as friends who share similar behaviors and attitudes (). Consistent with these claims are findings that ethnic background similarity is one of the most salient features of friend selection (), particularly during the early adolescent years, with the rise of ethnic identity and the development of a sense of self and community (). The importance of ethnic background similarity to interpersonal attraction is less clear in the case of Spanish-speaking youth. Not everyone with Spanish as their heritage language identifies as Hispanic, and not everyone who identifies as Hispanic speaks Spanish at home. Historical considerations loom large. Spanish is common in much of the Caribbean, but nevertheless there is considerable racial and ethnic diversity in populations. For families from these regions who move to North America, being Hispanic may be synonymous with speaking Spanish, and language may be what separates immigrants from the new majority culture. In other parts of Latin America, there is very little racial and ethnic diversity. For families from these regions who move to North America, being Hispanic may be synonymous with appearance and cultural practices, both of which separate immigrants from the new majority culture. Further, cultural practices may persist long after Spanish language use has waned, leading to a dissociation between speaking Spanish and being Hispanic. Thus, for many youth, language and ethnicity represent distinct aspects of identity, which are shaped by family history, community, and personal experience. Yet many other families view Spanish as the primary means of cultural transmission. In these families, speaking Spanish and being Hispanic are two sides of the same coin.