A substantial body of research shows that syntactic awareness is significantly related to both reading comprehension and reading fluency. Representative publications are listed here.
Breen, M., Kaswer, L., Van Dyke, J. A., Krivokapić, J., & Landi, N. (2016). Imitated prosodic fluency predicts reading comprehension ability in good and poor high school readers. Frontiers in Psychology, 7, 1026.
Catts, H. W., Adlof, S.A. & Weismer, S. E. (2006). Language deficits in poor comprehenders: A case for the simple view of reading. Journal of Speech, Language, and Hearing Research, 49(2), 278-293.
Dowhower, S. L. (1991). Speaking of prosody: Fluency’s unattended bedfellow. Theory into practice, 30(3), 165-175.
Groen, M. A., Veenendaal, N. J., & Verhoeven, L. (2019). The role of prosody in reading comprehension: Evidence from poor comprehenders. Journal of Research in Reading, 42(1), 37-57.
Kim, Y. S. G. (2015). Developmental, component‐based model of reading fluency: An investigation of predictors of word‐reading fluency, text‐reading fluency, and reading comprehension. Reading Research Quarterly, 50(4), 459-481.
Kuhn, M. R., Schwanenflugel, P. J., & Meisinger, E. B. (2010). Aligning theory and assessment of reading fluency: Automaticity, prosody, and definitions of fluency. Reading Research Quarterly, 45(2), 230-251.
Miller, J., & Schwanenflugel, P. J. (2006). Prosody of syntactically complex sentences in the oral reading of young children. Journal of Educational Psychology, 98(4), 839.
Miller, J., & Schwanenflugel, P. J. (2008). A longitudinal study of the development of reading prosody as a dimension of oral reading fluency in early elementary school children. Reading Research Quarterly, 43(4), 336-354.
Nation, K., Cocksey, J., Taylor, J. S., & Bishop, D. V. (2010). A longitudinal investigation of early reading and language skills in children with poor reading comprehension. Journal of Child Psychology and Psychiatry, 51(9), 1031-1039.
Ravid, D., & Mashraki, Y. E. (2007). Prosodic reading, reading comprehension and morphological skills in Hebrew‐speaking fourth graders. Journal of Research in Reading, 30(2), 140-156.
Wolters, A. P., Kim, Y. S. G., & Szura, J. W. (2022). Is reading prosody related to reading comprehension? A meta-analysis. Scientific Studies of Reading, 26(1), 1-20.