ECSS Paris 2023: OP-PN17
INTRODUCTION: Antihistamine medication blocks the functioning of the histamine system and is widely used to treat allergies. Intake of antihistamines during a six-week cycling training period results in marked impairments in training adaptations (1), likely due to an impaired intercellular histaminergic cross-talk initiated by mast cells in muscle (2). However, it remains unclear whether this is a universal mechanism of muscle adaptation. Therefore, we investigated the impact of antihistamine medication on resistance training adaptations. METHODS: Eighteen men were randomly assigned to either a placebo (n=9) or antihistamine (n=9, 180mg fexofenadine) group and performed 10 weeks of resistance training. Dietary intake was monitored using self-reported three-day food diaries (baseline, week 4, and week 6) and a dietitian ensured sufficient protein intake. Before and after the training program, maximal strength, muscle volume, fat mass, fat free mass, whole-body insulin sensitivity and vascular function were determined. Training-induced changes between groups were evaluated with two-way ANOVA tests or linear mixed models. RESULTS: Both the placebo and antihistamine groups showed similar increases in muscle volume (+6% and +7%, p=0.316) and maximal strength (+14% and +20%, p=0.083). Unexpectedly, the antihistamine group gained fat mass (+0.6kg), while the placebo group did not (-0.3kg, p=0.011). This result is reflected by the rise in total caloric and carbohydrate intake in the antihistamine, but not the placebo group (+34% vs +7%, p=0.064 and +29% vs -7%, p=0.005). Both groups showed reductions in mean arterial blood pressure (-2.5 mmHg, p=0.047) and diastolic blood pressure (-4.4 mmHg, p=0.004), as well as a decrease in total glucose level during the oral glucose tolerance test (-81 mM, p=0.001). Surprisingly, fasting glucose and insulin concentrations increased following training (+4%, p=0.041 and +25%, p=0.013, respectively), in both groups. CONCLUSION: Antihistamine intake did not alter resistance training adaptations, indicating that the intercellular histaminergic cross-talk initiated by mast cells is not a universal mechanism across training modalities. Unexpectedly, antihistamine intake led to increased food intake and fat mass following 10 weeks of resistance training, likely linked to the well-known role of histamine in appetite regulation. References: 1. Van der Stede et al. (2021). Science Advances, 7(16).; 2. Van der Stede et al. (2025). Cell Metabolism, 37(1-15).
Read CV Alexia Van de LoockECSS Paris 2023: OP-PN17
INTRODUCTION: Blood flow plays an important role in supplying oxygen to the exercising muscles. The impairment of oxygen supply via blood flow profoundly impacts exercise performance. Previous studies have shown a heterogeneity of the metabolic responses among the quadriceps muscle. For example, intramuscular blood flow measured by positron emission tomography is heterogeneous within the quadriceps muscle. Moreover, the kinetics of muscle deoxygenation during incremental exercise differ among muscles in the quadriceps. However, it is unknown the dynamics of intramuscular blood flow and its relationship to muscle deoxygenation within the quadriceps femoris. Therefore, the purpose of this study was to evaluate the changes in intramuscular blood flow, muscle deoxygenation, and their relationship in different muscles of the quadriceps femoris. METHODS: Thirteen healthy young men (19.4 ± 1.0 years) performed intermittent (5-second contraction, 5-second relaxation) and incremental isometric knee extensions. The exercise began at 30% of maximal voluntary contraction (MVC) and increased by 10% for every five contractions to 70% of MVC until task failure. Intramuscular blood flow using power Doppler ultrasonography and muscle deoxygenation using near-infrared spectroscopy (NIRS) were simultaneously measured from the vastus lateralis (VL), rectus femoris (RF) and vastus medialis (VM) in randomized order over 3 days. All variables were measured up to 5 minutes after task failure and averaged every 30 seconds. NIRS measurement provided muscle oxygen saturation (StO2) and deoxy-hemoglobin/myoglobin (deoxy-Hb/Mb). RESULTS: There were no significant differences in ΔIntramuscular blood flow, ΔStO2, and the ratio between intramuscular blood flow and deoxy-Hb/Mb among three muscles during exercise. However, significant regional differences were observed for all parameters after exercise. ΔIntramuscular blood flow was significantly higher in the RF (3 minutes; 1698.5 ± 1038.1 a.u., 4 minutes; 1573.9 ± 950.0 a.u.) than in the VL after 3 minutes post-exercise (824.6 ± 855.5 a.u., P = 0.009) and in the VM after 4 minutes post-exercise (713.7 ± 529.3 a.u., P = 0.037). ΔStO2 was significantly higher in the RF (3 minutes; 12.08 ± 5.36 %, 3.5 minutes; 11.78 ± 5.70 %) than in the VL after 3 minutes post-exercise (6.87 ± 3.11 %, P = 0.025) and in the VM after 3.5 minutes post-exercise (7.18 ± 5.88 %, P = 0.044). The ratio between intramuscular blood flow and deoxy-Hb/Mb was significantly higher in the RF (1.5 minutes; 15.10 ± 7.77 a.u. × 10^4, 3.5 minutes; 15.31 ± 9.74 a.u. × 10^4) than in the VL after 1.5 minutes post-exercise (9.31 ± 6.45 a.u. × 10^4, P = 0.044) and in the VM after 3.5 minutes post-exercise (4.94 ± 4.15 a.u. × 10^4, P = 0.016). CONCLUSION: These results suggest that the metabolic requirements in the RF are different from other quadriceps femoris during fatiguing knee extension.
Read CV Kazuma IzumiECSS Paris 2023: OP-PN17
INTRODUCTION: It has recently been identified that the highest power output at which energy supply is derived predominantly from the aerobic energy system, i.e., aerobic limit power (ALP), coincides with the upper boundary of the severe exercise intensity domain, defined as the highest power output that elicits maximal V̇O2 (i.e., PUPPERBOUND) (1). ALP is assessed based on V̇O2 dynamics during exercise, peak blood lactate concentration, and the fast phase of recovery V̇O2 kinetics, representing the contributions of aerobic, lactic, and phosphagen energy systems, respectively. A non-invasive alternative for estimating relative energy contribution rates is the maximal accumulated oxygen deficit (MAOD), which is defined as the difference between the estimated total oxygen cost of exercise and the accumulated oxygen uptake (2). Since the energy contribution rates derived from these two methodologies are often considered interchangeable (3), it is important to indicate that ALP as derived from MAOD still represents PUPPERBOUND. The aim of this study was to evaluate whether ALP, as determined by MAOD, coincides with PUPPERBOUND. METHODS: Thirteen physically active male individuals underwent a ramp incremental exercise test, followed by four submaximal, 6-7 maximal and at least one supramaximal constant-work-rate test to estimate PUPPERBOUND and MAOD-derived ALP. A linear regression line was plotted using data points from the relationship between V̇O2 responses and power outputs obtained from submaximal exercise tests and then extrapolated to target power outputs to calculate MAOD. The PUPPERBOUND was estimated based on the linear relationship between the time to achieve V̇O2max and the time to task failure. The ALP was estimated by MAOD, based on the difference between the predicted V̇O2 demand and the accumulated O2 uptake. RESULTS: The ALP derived from MAOD and PUPPERBOUND were not significantly different (p= 0.16; ES: 0.42) and they were interchangeable (r: 0.99; Bias: 3±7 W; SEE: 7 W; LoA: −11 to 17 W). Pulmonary V̇O2 just above ALP was significantly different from V̇O2max (Δ: 4±3 mL/min/kg; p<0.001). When ALP was exceeded, relative contribution rates obtained from the energy systems shifted and anaerobic contribution rate above ALP was significantly higher than that of ALP (51% vs 46%; p<0.001). CONCLUSION: This study demonstrated that ALP, as derived from the MAOD method, provides a simple, cost-effective, and non-invasive approach to accurately determine the PUPPERBOUND. 1. Peker et al (2024) 2. Medbø et al (1988) 3. Bertuzzi et al (2010)
Read CV Arda PekerECSS Paris 2023: OP-PN17