Objectives: We sought to determine if individualized programming by heart rate variability (HRV), improves resistance training outcomes in American football players. Design and Methods: Twenty-seven National Collegiate Athletic Association (NCCA) Division II American football players (age 19.03 ± .98 y, height 185.50 ± 5.30 cm, body mass 100.59 ± 18.57 kg) were divided into an experimental (HVG) group (n = 11), and a control (CON, n = 16). Subjects completed 5-weeks of 3 d·wk -1 periodized

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... tance training during the offseason. The HVG monitored HRV on mornings before training, and their training volume was adjusted by their HRV. Specifically, on training days when HRV indicated that a subject was fatigued, the subject performed half of the originally planned repetitions for the training day. CON performed assigned workouts with no alterations. Performance was assessed via 1RM bench press (BP), power clean (PC), back squat (BS), and vertical jump (VJ) between groups using a 2 × 2 repeated measures analysis of variance (ANOVA). Results: The HVG had an average of 4 ± 1.51 days modified over the 5 wks, but volume load lifted was similar (p = 0.955) between groups. Repeated measures ANOVA revealed significant increases in BP (time effect p < .001), BS (time effect p < 0.001), PC (time effect p = 0.002), and VJ (time effect p = 0.042) for both HVG and CON. There were no significant betweengroup differences in performance variables. The group × time interaction for PC (p = 0.087) trended towards a significantly greater increase in HVG (+ 8.6%) vs. CON (+ 2.6%). Conclusions: Periodized training can improve performance without monitoring HRV, but it may have an advantageous effect for highly technical movements such as the PC.