ECSS Paris 2023: OP-PN01
INTRODUCTION: Female-specific research examining post-exercise refuelling is scarce, and the effect of varied carbohydrate sources remains unclear. Additionally, ketone monoester (KME) supplementation is thought to aid recovery by increasing glycogen resynthesis and circulating erythropoietin (EPO), but how females respond to KME is also unknown. This study assessed the effect of a high-carbohydrate diet consisting of: A) typical food items with non-caloric placebo (CON), B) potato-based meals with non-caloric placebo (POT) or, C) potato-based meals with KME (PKE), on skeletal muscle glycogen resynthesis, blood endocrine and metabolic parameters, and subsequent exercise performance. We hypothesized that PKE during recovery would elicit a distinct blood endocrine response and enhance skeletal muscle glycogen resynthesis, thereby improving subsequent exercise performance. METHODS: Following a randomized, counterbalanced, placebo-controlled, double-blind, crossover design, 9 Tier 2 female endurance athletes (mean ± SD: age 28 ± 7, body mass 63.6 ± 7.4, maximal oxygen uptake: 45 ± 3.8 ml/kg/min) completed an exhaustive cycle ergometer glycogen-depleting exercise (EX-1) followed by the ingestion of 0.8 g/kg/h CHO and 0.4 g/kg/h protein at 0 and 1 h, and 1.2 g/kg/h CHO at 2 and 3 h (all equal in PKE, POT, and CON). Concomitant with the diets, participants ingested four doses of KME in PKE (0.5, 0.25, 0.25, and 0.25 g/kg), provided at 0, 1, 2, and 3 h of recovery, while POT and CON received volume-matched non-caloric placebo. Following a 4 h recovery, participants completed a ~20-min laboratory-based cycling time trial (TT). Skeletal muscle samples from the vastus lateralis were taken immediately post-EX-1 and pre-TT, and glycogen concentrations were determined using the acid hydrolysis method. Blood samples were drawn throughout and analysed for β-hydroxybutyrate (βHB), glucose, insulin and EPO. RESULTS: βHB concentrations were higher in PKE (range: ~2.2–3.2 mM) vs POT and CON (~0.1 mM, P < 0.01) throughout recovery. Glucose tAUC, calculated across recovery and post-TT, was ~17% lower in PKE vs POT (P = 0.08) and ~19% lower vs CON (P = 0.02). No treatment effects were observed for insulin or EPO tAUC during recovery (P > 0.05). Muscle glycogen resynthesis rates did not differ between treatments (PKE: 26 ± 11 mmol/kg/h; POT: 24 ± 12 mmol/kg/h; CON: 27 ± 8 mmol/kg/h; P = 0.97), nor did subsequent TT performance (PKE: 1458 ± 180 s; POT: 1445 ± 185 s; CON: 1428 ± 157 s; P = 0.54). CONCLUSION: Contrary to our hypothesis, adding KME to an optimal post-exercise recovery strategy did not positively modulate endocrine responses, glycogen resynthesis, or exercise performance in Tier 2 female endurance athletes. These findings question the efficacy of KME to enhance post-exercise recovery beyond optimal nutrition and provide novel female-specific insights into post-exercise recovery with varied carbohydrate sources.
Read CV Erick MosqueraECSS Paris 2023: OP-PN01
INTRODUCTION: Resistance exercise training (RET) induces skeletal muscle hypertrophy and strength gains. In women, cyclic fluctuations in estradiol and progesterone across the menstrual cycle have been hypothesized to influence anabolic and catabolic signaling and thereby modulate RET adaptations. Despite growing interest in menstrual cycle-based training prescriptions, evidence is inconsistent, largely due to inadequate hormonal confirmation and poor control of RET training volume. We aimed to determine whether menstrual cycle phase-specific manipulation of training volume enhances muscle hypertrophy and strength. Aligning with proposed paradigms, we hypothesized that follicular phase-emphasized (greater volume) would enhance RET-induced adaptation. METHODS: Twenty-four healthy, eumenorrheic women completed a within-participant, unilateral resistance training intervention across three consecutive menstrual cycles. Menstrual cycle phase was prospectively tracked and confirmed with blood and urine measures. Each leg was allocated to one of four conditions: non-exercising control (CON), continuous training with equal volume across phases (EX), high-volume training in the follicular phase and low volume in the luteal phase (HV-FOL), or high-volume training in the luteal phase and low volume in the follicular phase (HV-LUT). High volume consisted of five sets per exercise performed twice weekly (≥10 sets per muscle per week), and low volume consisted of one set per exercise twice weekly (≤5 sets per muscle per week). Primary outcomes were thigh lean mass (DXA), vastus lateralis cross-sectional area (ultrasound), fat-free mass (bioelectrical impedance), and muscle fiber cross-sectional area. Secondary outcomes included one-repetition maximum (1RM) leg press and leg extension strength and maximal voluntary isometric contraction. RESULTS: All training conditions elicited greater increases in thigh lean mass, muscle cross-sectional area, fat-free mass, and 1RM strength compared with CON (all p<0.001). No differences were detected between EX, HV-FOL, and HV-LUT for any hypertrophy or strength outcome (all p>0.17 ). CONCLUSION: When menstrual cycle phase is rigorously confirmed and RET volume is matched, phase-based manipulation of training volume does not affect muscle hypertrophy or strength compared with continuous RET. These findings demonstrate that training volume-load, rather than menstrual cycle timing and emphasis on follicular phase heavy loading, is the primary determinant of RET-induced muscular adaptation in eumenorrheic women. Menstrual cycle-based programming may support individual preference but is not required to maximize RET outcomes.
Read CV Alysha DSouzaECSS Paris 2023: OP-PN01
INTRODUCTION: Running economy (RE) reflects the metabolic cost of running at a given submaximal speed and influences distance-running performance, particularly in trained athletes for whom VO2max and lactate threshold approach maximal levels [1]. In eumenorrheic females, RE may vary according to fluctuations in estrogen and progesterone levels across the menstrual cycle through effects on substrate utilization, cardiovascular regulation, and neuromuscular control [2]. However, evidence for menstrual cycle-related differences in RE remains inconsistent, largely due to indirect phase classification or two-phase study designs [2]. The purpose of this study was to examine metabolic responses to running across three hormonally distinct menstrual cycle phases. METHODS: Sixteen eumenorrheic trained female runners (age 28.4 +/- 5.9 y; BMI 20.7 +/- 2.2 kg/m^2; 5-km personal best: 16:30 - 27:00) completed an incremental treadmill running test during the early follicular (EF), late follicular (LF), and mid-luteal (ML) phases. We verified menstrual cycle phase using calendar tracking, urinary luteinizing hormone measurement, and serum estradiol and progesterone measurements. We measured oxygen consumption (VO2), heart rate (HR), and respiratory exchange ratio (RER). We modeled individualized phase-specific linear relationships between these variables and running speeds below the first ventilatory threshold (VT1) using linear mixed-effects models. RESULTS: Oxygen cost differed across menstrual-cycle phases (p = 0.046), with the highest cost in EF (0.173 +/- 0.035 L/min per km/h), followed by ML (0.164 +/- 0.027) and LF (0.151 +/- 0.036), with a significant EF-LF contrast (p = 0.014). Energetic cost showed a similar phase-dependent pattern (p = 0.043), with the highest cost in EF (0.889 +/- 0.179 kcal/min per km/h), followed by ML (0.845 +/- 0.138) and LF (0.788 +/- 0.169), and a significant EF-LF contrast (p = 0.013). Phase was not associated with differences in how HR or RER changed with speed (p = 0.739 and p = 0.329). CONCLUSION: Running economy differed across menstrual-cycle phases, with lower oxygen cost (better running economy) in the LF phase compared with the EF phase. Differences in energetic cost were primarily associated with differences in oxygen cost, as no differences were observed in RER or HR. Because VT1 corresponds to a sustainable intensity at which most endurance training volume is performed, these findings indicate that menstrual-cycle phase may influence the physiological demands of a given training load. Further investigation is needed to clarify the hormonal, biomechanical, and perceptual mechanisms underlying these phase-related differences and their implications for endurance performance. References 1. Barnes KR, Kilding AE. Sports Med Open 2015;1:8. 2. McNulty KL, Elliott-Sale KJ, Dolan E, et al. Sports Med 2020;50:1813-1827.
Read CV Ephrem MekonnenECSS Paris 2023: OP-PN01