Purpose: To verify the reciprocal longitudinal relationships between cardiorespiratory fitness (CRF), percentage body fat (%body fat), and metabolic syndrome in Brazilian primary school students. Method: This longitudinal study involved 420 children and adolescents followed for 3 years (2011–2014). The continuous Metabolic Syndrome (cMetSyn) score was calculated by summing adjusted z scores of glucose, systolic blood pressure, total cholesterol/high-density lipoprotein cholesterol ratio, triglycerides, and waist circumference. The CRF was assessed using running/walking tests, and %body fat was assessed through sex-specific 2-site skinfold thickness. Cross-lagged panel models were used to analyze longitudinal reciprocal relationships between CRF and %body fat with cMetSyn. Results: Results indicated that 2011 %body fat significantly predicted both 2014 CRF scores and 2014 cMetSyn scores (P < .001); however, 2011 CRF only predicted 2014 %body fat (P < .001) but not 2014 cMetSyn (P = .103). Furthermore, 2011 cMetSyn predicted 2014 %body fat (P = .002). The model explained 36%, 48%, and 37% of the variance in 2014 CRF, %body fat, and cMetSyn, respectively. Conclusion: The results suggest a reciprocal inverse relationship between %body fat and metabolic syndrome risk and that %body fat may play a more important role in the risk of developing metabolic syndrome compared with CRF.

目的：验证巴西小学生心肺适能 (CRF)、体脂百分比 (%body fat) 和代谢综合征之间的相互纵向关系。方法：这项纵向研究涉及 420 名儿童和青少年，随访 3 年（2011-2014 年）。连续代谢综合征 (cMetSyn) 评分是通过对调整后的z值求和来计算的血糖、收缩压、总胆固醇/高密度脂蛋白胆固醇比率、甘油三酯和腰围的分数。使用跑步/步行测试评估 CRF，并通过性别特异性 2 位点皮褶厚度评估体脂百分比。交叉滞后面板模型用于使用 cMetSyn 分析 CRF 和体脂百分比之间的纵向相互关系。结果：结果表明，2011 年体脂百分比显着预测了 2014 年 CRF 评分和 2014 年 cMetSyn 评分（P  < .001）；然而，2011 年 CRF 仅预测了 2014 年的体脂百分比 ( P  < .001) 而不是 2014 年的 cMetSyn ( P  = .103 )。此外，2011 年 cMetSyn 预测 2014 年体脂百分比 ( P = .002）。该模型分别解释了 2014 年 CRF、体脂百分比和 cMetSyn 中 36%、48% 和 37% 的方差。结论：结果表明，体脂百分比与代谢综合征风险之间存在倒数关系，与 CRF 相比，体脂百分比可能在代谢综合征风险中发挥更重要的作用。