ECSS Paris 2023: OP-PN04
INTRODUCTION: Exercise training is an effective tool for preventing lifestyle-related diseases [1]. However, individuals exhibit considerable variability in their responses to standardized exercise training programs [2,4]. Sex-based differences may contribute to this variability in adaptive capacity [2,3], but this remains a topic of debate. Studies examining VO2max changes indicate conflicting results regarding sex differences, both in long-duration (39-52 weeks; [2,4]) and short-duration (≤8 weeks; [3]) training interventions. A recent meta-regression study reported that females demonstrated greater percentage changes in VO2max compared to males, while absolute changes (mL/min/kg) were comparable between sexes [5]. However, it is still unclear whether long-term aerobic exercise training leads to similar VO2max changes in females and males. Hence, this study examined whether 11 months of aerobic exercise training induce similar percentage and absolute changes in VO2max in middle-aged females and males. METHODS: Untrained but healthy middle-aged females (59±6 years; VO2max, 27.3±7.5 mL/min/kg; n=12) and males (52±8 years; VO2max, 38.8±5.3 mL/min/kg; n=15) underwent 48 weeks of aerobic exercise training. The program included 100 cycling sessions (45min each), of which 87 sessions were supervised. Training sessions alternated between high-intensity intervals (4x5min, 5x5min, and 5x8min) and moderate-intensity sessions (6x6min or 45min of continuous exercise). VO2max was determined before the intervention period, and after 8, 22, 32, 40, and 48 weeks of training. Values were normalized to body mass, and both absolute and percentage changes were analyzed longitudinally using a linear mixed-effects model with repeated measures. Time points and sex were treated as fixed effects, with individual participants modeled as random effects. 95% confidence intervals (CIs) were calculated to interpret the results. RESULTS: Eleven months of aerobic exercise training increased VO2max in both females (4.8±1.4 mL/min/kg; 18.4±6.7%) and males (4.6±3.1 mL/min/kg; 12.8±9.3%). No sex differences were observed in absolute VO2max changes (ml/min/kg) at any time point (95% CIs including zero). However, females demonstrated greater percentage increases in VO2max compared to males after 32, 40, and 48 weeks of training (4.7, 5.2, and 5.6%-points difference, respectively; 95% CIs not including zero). CONCLUSION: When middle-aged females and males undergo the same 11-month aerobic exercise training program, absolute VO2max increases (scaled to body mass) are comparable between sexes. However, females exhibit greater percentage increases in VO2max compared to males. These findings demonstrate that middle-aged females do not have a reduced capacity to increase VO2max through aerobic exercise training compared to males. References: [1] Pedersen & Saltin (2015). SMSS. [2] Howden et al. (2015). JAP. [3] Diaz-Cañestro & Montero (2019). Sports Med. [4] Kohrt et al. (1991). JAP (1985). [5] Mølmen et al. (2025). Sports Med.
Read CV Tomas UrianstadECSS Paris 2023: OP-PN04
INTRODUCTION: Iron availability has been proposed as one of the main factors explaining the high variability in hemoglobin mass (Hbmass) adaptation to hypoxia (1), however, little is known about hypoxia-induced changes in the iron regulatory pathways. In sustained hypoxia, iron availability is supported by the down-regulation of the systemic iron regulator hepcidin via hormones erythroferrone (ERFE) and erythropoietin (EPO). (2) This study investigated the effects of a 21-day live high-train low (LHTL) on iron availability in female endurance athletes by determining the changes in EPO-ERFE-hepcidin axis and routine iron markers serum ferritin and serum transferrin receptor (sTfR) and whether these changes are associated with Hbmass adaptations. METHODS: 15 participants completed either a 21-day LHTL period in normobaric hypoxia (2500 m, ~18 h∙day−1) (INT, n=8) or lived and trained at sea level for the same duration (CON, n=7). All participants conducted PRE and POST tests one to two days before and after the intervention. The tests included Hbmass assessment via the carbon monoxide rebreathing method and resting venous blood samples to test for changes in EPO, ERFE, hepcidin, ferritin, and sTfR. For INT an additional venous blood sample was collected on the 6th morning in hypoxia (MID, 111 ± 5 h in hypoxia) to investigate short-term changes in blood biomarkers. RESULTS: Normobaric hypoxia increased Hbmass (3.8 ± 2.0 %, p<0.001) in INT, while no changes were detected in CON. In INT, serum EPO increased 35.6 % (p=0.037) from PRE to MID, followed by a -42.4 % decrease from MID to POST (p=0.019). In INT there were no changes in ERFE, hepcidin, or ferritin from PRE to MID or POST but sTfR increased 13.9 % (p=0.013) from PRE to POST. In CON there were no changes in any of the iron markers at all time points. Changes in Hbmass were not associated with changes in ERFE or hepcidin in either group. However, a higher Hbmass was associated with a smaller reduction in ferritin during the first 5 days of hypoxia in INT (r=0.87, p=0.005). CONCLUSION: The results of the present study suggest that hepcidin and ERFE may not provide additional information regarding changes in iron demand and availability during and within the few days following prolonged hypoxic exposure compared to routine iron markers. The association between Hbmass and serum ferritin, in turn, underlines the necessity of maintaining adequate ferritin levels during hypoxia to support hematological adaptations, thereby supporting the current practical recommendations of dietary and supplementary iron use prior to and during prolonged hypoxia. (1) REFERENCES: 1. Stellingwerff T, et al. Nutrition and altitude: strategies to enhance adaptation, improve performance and maintain health: a narrative review. Sports Med. 2019;49(2):169-184. 2. Robach P, et al. Induction of erythroferrone in healthy humans by micro-dose recombinant erythropoietin or high-altitude exposure. Haematologica. 2020;106(2):384-390.
Read CV Titta KuorelahtiECSS Paris 2023: OP-PN04
INTRODUCTION: Research using ovariectomy models in rats and hormone replacement therapy in postmenopausal females suggest, that the female sex hormones oestrogen (O) and progesterone (P) may influence rates of myofibrillar protein synthesis (MyoPS) and, therefore muscle growth/remodelling. However, limited data are available on how fluctuating low and high endogenous O and P concentrations across phases of the menstrual cycle (MC) impact MyoPS in young females. This study aimed to investigate MyoPS in a postabsorptive state and in response to exercise and nutrition, when O and P concentrations are low and high, during the early follicular (EF) and mid-luteal (ML) phases of the MC, respectively. To provide further insight into the effect of sex hormones on MyoPS, whole-body protein turnover and expression of genes involved in muscle mass regulation were also measured. METHODS: Fourteen healthy females (age: 25±7 y; BMI: 24±2 kg/m2) were recruited to this randomised cross-over study. Following two months of menstrual cycle tracking, participants completed two experimental trials during EF (4±2 d following menses; O 160±60 pmol/L, P 1.3±0.7 nmol/L) and ML phases (7±1 d following luteinising hormone surge; O 729±332 pmol/L, P 40.5±17.7 nmol/L), using best practice methodologies to confirm MC phases. On each visit, participants received a primed continuous infusion of L-[ring-2H5]phenylalanine and L-[3,3-2H2]-tyrosine for 6.5 h. Following a bout of resistance exercise, participants ingested a drink containing 1.5 g of essential amino acids. Muscle biopsies were collected before and during the 3 h postexercise postprandial period to assess MyoPS and gene expression. Blood samples were collected to assess amino acid concentrations and whole-body protein turnover. Two-way ANOVAs were performed to detect changes across MC phases. Data are expressed as means±SD. RESULTS: Total plasma amino acid concentrations were lower overall in the ML compared to the EF phase (P<0.001). Exercise and drink ingestion increased basal (0.035±0.023 and 0.036±0.013 %⋅h-1) MyoPS rates between 0-3 h to 0.066±0.028 and 0.060±0.020 %⋅h-1 (P<0.001), for EF and ML, respectively, with no differences between phases at either time point (P=0.329). Exercise and drink ingestion decreased whole-body protein synthesis below basal rates by 18±5% (P<0.0001), suppressed protein breakdown by 31±6% (P<0.0001), which resulted in whole-body net protein balance shifting from negative to positive (P<0.0001), with no differences between EF and ML phases (all P>0.050). Expression of several genes associated with protein synthesis, muscle remodelling and sex hormone signalling were increased in ML vs EF phase, whereas protein breakdown associated genes were decreased. CONCLUSION: Despite decreased circulating amino acid concentrations and a gene expression profile consistent with muscle growth, MyoPS, whole-body protein turnover and hence muscle growth/remodelling do not appear to be affected by increased O and P during the ML phase of the MC.
Read CV Marianna ApicellaECSS Paris 2023: OP-PN04