ECSS Paris 2023: CP-PN04
INTRODUCTION: Irisin is a myokine mainly released in response to exercise, playing a role in energy expenditure, white adipose tissue browning, and metabolic regulation (1). While it is widely recognized that aerobic exercise consistently increases plasma irisin levels (2), the response to resistance exercise remains inconclusive. Some studies report increased irisin levels following resistance exercise, while others show no change or a decrease (3, 4). Additionally, irisin analysis is usually assessed in blood samples, which are invasive and may not always be practiced in some settings. Saliva sampling offers a non-invasive alternative, but limited research has evaluated its reliability for irisin detection to date (5). This study aimed to investigate acute irisin responses in both plasma and saliva following a high-volume resistance training session. METHODS: Seven healthy, resistance-trained men (23.5±2.5 years; training experience: 5±3 years) were enrolled. The study involved three preliminary test sessions (10RM, TUT, 1RM) and one experimental training session (TS). The TS consisted of 30 sets performed to failure, with a time under tension (TUT) of 5-1-2-1, emphasizing eccentric movements. Blood and saliva samples were collected at baseline (T0), 15 minutes (T1), 24 hours (T2), and 48 hours post-exercise (T3). Plasma and salivary irisin levels were measured by ELISA, while plasma creatine kinase (CK) and visual analogue scale (VAS) levels were analyzed as indirect markers of muscle damage. Nonparametric statistical tests (Friedman and Pearson correlation) were applied, with significance set at p<0.05. RESULTS: Plasma irisin levels significantly increased between T0 and T1 (10.44 ± 0.9 to 11.38 ± 1.4 ng/mL, p<0.05). Similarly, salivary irisin levels rose significantly from 0.051 ± 0.006 to 0.053 ± 0.008 ng/mL (p<0.05). CK values peaked at T2, confirming markedly exercise-induced muscle damage (p<0.001). Also, VAS values peaked at T2 to then decrease at T3, suggesting that muscle soreness was higher 24 h after exercise. A significant correlation was observed between percentage changes in plasma and salivary irisin (ρ= 0.86, p<0.05), suggesting a potential link between the two biological fluids in irisin release kinetics. CONCLUSION: This pilot study is the first to suggest a concurrent increase of plasma and salivary irisin following high-volume resistance exercise in trained men. The correlation between plasma and salivary irisin suggests that saliva sampling may serve as a viable and non-invasive method for assessing irisin responses to resistance exercise. Future research should investigate the increase of salivary irisin concentration in larger cohorts and different training modalities. References 1. Boström P,. Nature. 2012;481(7382):463–8. 2. Tommasini E,. Eur J Transl Myol. 2024. 3. Tsuchiya Y,. Metabolism. 2015;64(9):1042–50. 4. Pekkala S,. J Physiol. 2013;591(21):5393–400. 5. Missaglia S,. Eur J Transl Myol. 2023;33(1).
Read CV Luigi MaranoECSS Paris 2023: CP-PN04
INTRODUCTION: Near-Infrared Spectroscopy (NIRS) allows non-invasive assessment of tissue oxygenation and provide insights into skeletal muscle metabolism and fatigue in sports and health context. For these reasons, NIRS devices have recently gained attention and popularity. Most NIRS devices (i.e. based on continuous wave technique) assume constant optical parameters of the tissue investigated (i.e., differential path length factor (DPF)) which influence hemodynamic measurements’ accuracy. However, the DPF differs between individuals, measurement sites, adipose tissue under the probe and potentially exercise intensity. More advanced time-domain (TD) NIRS enable real-time DPF retrieval and could therefore improve measure accuracy with significant impact on NIRS applications. This study investigated the evolution of DPF and tissue oximetry values at different intensities of muscle contractions and examined their relationship with skinfold thickness (ST). METHODS: Ten healthy subjects (6F, 4M, BMI: 18.2-28.8) performed a knee extensor isometric contraction protocol. A 2-min baseline was followed by a warm-up and an initial maximum voluntary contraction (MVC). Subjects were then asked to perform 10s contractions at 25, 50, 75 and 100% of their MVC. Muscle oxygenation (MO) variables at the vastus lateralis were continuously monitored using the NIRSBOX tissue oximeter (PIONIRS, Italy). DPF and the evolution of MO variables (e.g. muscle oxygen saturation (StO2)) were determined as the peak responses (min/max) reached during a 20s window from the onset of contraction. DPF across intensities were compared using repeated measures ANOVA and the relationships between ST and both DPF and MO parameters were investigated by Pearson correlations. RESULTS: The group mean ST was 14.3mm (range: 7.3-21.9mm). DPF at baseline was correlated with ST (R²=0.66, p<0.01). The minimum measured DPF decreased with exercise intensity (p<0.05) and stabilised at 75% of MVC. Individual slopes of the decrease in DPF were not correlated to ST (p<0.05). Additionally, there was no significant correlation between ST and StO2 at baseline (p>0.05) and the overall change of minimum StO2 from baseline across all intensities (p>0.05). All other NIRS parameters showed the same behaviour relative to ST. CONCLUSION: DPF is a key factor in tissue oximetry measurement, varying dynamically during exercise, particularly with contraction intensity. ST appears to strongly influence DPF which could lead to measurement errors if not considered. In our study using TD-NIRS oximetry, ST did not hinder the tracking of MO variables. Our findings, which need to be validated across a broader range of ST levels, are likely due to TD-NIRSs ability to directly measure DPF, which helps to account for the optical effects of local ST.
Read CV Thomas MONOTECSS Paris 2023: CP-PN04
INTRODUCTION: Bone mineral content (BMC) and bone mineral density (BMD) are crucial factors related to the risk of bone fractures, a severe injury, leading to long recovery periods. Blood markers like osteocalcin, PINP, and β-CTX-I reflecting bone metabolism, balancing between bone formation and bone resorption. It was hypothesized that BMD, BMC, and bone markers would fluctuate between preseason and competitive periods, with elite players demonstrating more stable values due to long-term skeletal adaptations, whereas sub-elite players, especially females, would show greater variability due to differences in training load and competition exposure. METHODS: This study examined BMD, BMC, osteocalcin, PINP, and β-CTX-I changes from early preseason to competitive seasons in elite and sub-elite male football players and sub-elite female players. Players from one professional male football team (Danish 1st tier), two sub-elite female teams (Danish 2nd tier), and three sub-elite male teams (Danish 3rd tier) participated in the study. Laboratory testing occurred in January (winter preseason), in March (competitive season for elite male players but the final part of preseason for sub-elite players) and summer (August/September for the elite male team and in June for the female teams). Testing involved whole-body dual-energy x-ray absorptiometry (DXA) scans to determine total and regional BMD and BMC (323 observations), and venous blood samples taken immediately before the scan for osteocalcin, PINP, and β-CTX-I (273 observations) that were analyzed using mixed models and independent t-tests for comparisons between different periods, gender and competitive levels. RESULTS: BMD fluctuated in elite male players, decreasing in summer (1.41±0.09 g/cm²) compared to January (1.50±0.10 g/cm², p=0.008) and March (1.50±0.10 g/cm², p=0.006), primarily in the upper body. Additionally, elite male players had higher BMD (1.50±0.10 g/cm²) than sub-elite male players (1.39±0.08 g/cm², p=0.001). However, sub-elite male players had higher BMD (1.39±0.08 g/cm²) and BMC (3607±361 g) than sub-elite female players (1.31±0.09 g/cm², 2786±317 g, p=0.001). Blood markers did not significantly vary across periods, but gender differences were found in sub-elite players: males had higher β-CTX-I (1049±527 ng/L) than females (500±260 ng/L, p=0.001). Sub-elite males had higher osteocalcin (32±15 µg/L) and β-CTX-I (1049±527 ng/L) than elite males (osteocalcin: 25±11 µg/L, p=0.009; β-CTX-I: 659±434 ng/L, p=0.001). CONCLUSION: Elite male players have denser bones and require less remodeling, likely due to years of high-intensity training and structured recovery. In contrast, sub-elite players may experience greater fluctuations and higher turnover markers due to a more varied and less structured training load. This highlights the importance of load management and tailored training to support bone health throughout an athletes career.
Read CV Georgios ErmidisECSS Paris 2023: CP-PN04