O’Neal, EK, Knight, SN, Bowling, LR, Scudamore, EM, Scudamore, V, and Waldman, HS. Running economy assessment at 90% of 5-km pace is more informative than lower intensities among women's NCAA Division I cross-country competitors. J Strength Cond Res XX(X): 000–000, 2026—National Collegiate Athletics Association (NCAA) women's cross-country (XC) runners compete at distances of 5–6 km producing respiratory exchange ratios (RER) > 0.99 at race pace. This prevents calculation of the most sensitive unit of running economy (RE) metabolic cost (MC). This study first established the steady-state characteristics of V̇ o ₂ and RER using 60-s sampling intervals during the last 2-minute of 5-minute RE bouts at individual 5-km race pace (5RP) and 70, 80, and 90% 5RP of 13 NCAA Division I Women's XC runners. After confirming steady state was not compromised by intensity, the relationship of V̇ o ₂ and RER between 100% 5RP and submaximal paces were explored. Min-4 and min-5 Cohen's d effect sizes were <0.07 for V̇ o ₂ at all submaximal velocities, and RER at lowest (70%; d = 0.25) and highest (90%; d = 0.29) intensities were similar. Strong relationships ( r ≥ 0.89; p < 0.001) between V̇ o ₂ for 70, 80, and 90% to 5RP were exhibited. However, RER for 70% ( r = −0.10) and 80% ( r = −0.12) both produced inverse, nonsignificant relationships to 5RP. By contrast, 90% produced an r = 0.62 ( p = 0.03), and no runner's RER exceeded 0.99. For performance analysts and NCAA Women's XC coaches using RE to detect training intervention efficacy, metabolic steady state is (a) uncompromised at 90% of 5RP, (b) permits MC calculation, and (c) better reflects 5RP metabolic profile than lower intensities.

Nutritional habits prior to exercise can influence metabolic processes both during and after an exercise bout. Due to the negative impact of excess body fat on metabolic health, pre-exercise nutrition and exercise interventions that target improved fat oxidation following exercise are warranted. The purpose of this study was to examine the combined effects of pre-exercise nutrition interventions and high-intensity resistance training (HIRT) on post-exercise substrate utilization in overweight (OW) females. Respiratory exchange ratio (RER) was measured in 15 recreationally active OW females at baseline (BASE), immediately post (IP), 30 min (30), and 60 min (60) post-HIRT following ingestion of the following supplements: carbohydrate (CHO), protein (PRO), CHO+CAFF (3 mg/kg body mass), or PRO+CAFF in a randomized, crossover, double-blind design. RER was not significantly different between any of the nutrition interventions (all p > 0.05). However, independent of pre-exercise nutrition ingestion, RER was significantly lower at 30 (0.75 ± 0.05; p < 0.01) and 60 (0.74 ± 0.05; p < 0.01) post-exercise in comparison to BASE (0.81 ± 0.05) and IP (0.78 ± 0.06). Collectively, RER decreased during recovery following HIRT in OW females, regardless of pre-exercise nutrition habits.