The regulation of human iron metabolism in hypoxia

Athletes commonly use altitude exposure in an attempt to improve their aerobic performance at sea level. Altitude exposure enhances erythropoiesis and iron-dependent oxidative and glycolytic enzyme production, for this reason, athletes must maintain a healthy iron balance at altitude. A negative iron balance at altitude may limit such physiological adaptations, potentially reducing the performance benefits of altitude exposure. This thesis examined the regulation of iron metabolism during acute (~31 min, Study One) and prolonged altitude exposure (14 days, Study Two). Finally, Study Three examined how daily oral iron supplementation influenced haemoglobin mass (Hbmass) and iron parameter responses to prolonged, moderate altitude exposure in a large cohort of elite athletes. Specifically, Study One found acute (~31 min) interval exercise [5 × 4 min at 90% of the maximal aerobic running velocity (vVO2max)] increased post-exercise interleukin-6 (IL-6) production and elevated hepcidin production 3 h thereafter in both normoxia (fraction of inspired oxygen (FIO2) = 0.2093) and normobaric hypoxia (i.e. 3,000 m simulated altitude; FIO2 = 0.1450). These results suggest exercise performed in acute hypoxia does not alter the post-exercise hepcidin response, relative to exercise in normoxia, possibly owing to the short duration of the hypoxic stimulus. Prolonged altitude exposure suppresses resting hepcidin levels in sojourning mountaineers, but its influence on the post-exercise hepcidin response exercise has not yet been investigated. Therefore, Study Two investigated how 14 days of live high: train low (LHTL) (exposure to 3,000 m simulated altitude for 14 h.d-1) influenced resting levels of hepcidin, erythropoietin (EPO) and blood iron parameters. Study Two also examined the post-exercise hepcidin and iron parameter responses to interval exercise (5 × 1,000 m at 90% of the maximal aerobic running velocity) performed in normoxia (600 m natural altitude) and normobaric hypoxia (i.e. ~3,000 m simulated altitude), following 11 and 14 days of LHTL. The post-exercise hepcidin response was compared with interval exercise performed at a matched exercise intensity in normoxia or hypoxia before LHTL. Here, LHTL suppressed resting hepcidin levels after two days of exposure, but the post-exercise hepcidin response to interval exercise was similar in normoxia and hypoxia, both before and after LHTL. Additionally, Hbmass increased by 2.2% and plasma ferritin levels decreased following LHTL. In conclusion, prolonged, moderate altitude exposure suppresses resting hepcidin levels, which likely ensures more iron can be transported to the erythron to support accelerated erythropoiesis. Prolonged altitude exposure places a large burden on body iron stores because additional iron is required to support accelerated erythropoiesis. Accordingly, athletes often ingest oral iron supplements during altitude exposure to ensure they maintain a healthy iron balance. By analysing ten years of haematological data collected from welltrained athletes who undertook two-to-four weeks of LHTL at simulated (3,000 m) or natural (1,350-2,700 m) altitudes, Study Three established how oral iron supplement dose moderates the Hbmass, serum ferritin and transferrin saturation response to prolonged moderate altitude exposure. In general, athletes supplemented with 105 mg.d- 1 or 210 mg.d-1 of oral iron supplement increased their Hbmass from pre-altitude levels by 3.3% and 4.0% respectively. Serum ferritin levels decreased by 33.2% in non-iron supplemented athletes and by 13.8% in athletes supplemented with 105 mg.d-1 of oral iron, however, those athletes who ingested 210 mg.d-1 markedly increased their iron storage compartment by 36.8% after moderate altitude exposure. Thus, daily oral iron supplementation at altitude assists athletes to maintain a healthy iron balance, providing them with sufficient iron to sustain accelerated erythropoiesis. In conclusion, this thesis suggests exercise in acute hypoxia does not seem to alter the post-exercise hepcidin response relative to exercise in normoxia, but prolonged altitude exposure suppresses resting hepcidin levels and may attenuate the magnitude of postexercise hepcidin response after 14 days of LHTL. Finally, daily oral iron supplementation may support iron balance and Hbmass production in athletes undertaking prolonged moderate altitude exposure

Validity and reliability of an incremental double poling protocol in cross-country skiers

This study determined the validity and reliability of an incremental double poling protocol performed on a Concept II ski-ergometer and validated this against an existing treadmill ski-striding protocol. Ten well-trained male cross-country skiers (age: 19 ± 1.4 y; height: 182 ± 72 cm; body mass: 76.0 ± 10.8 kg, whole body VO2Peak: 5.2 ± 1.0 L.min-1; upper body VO2Peak: 4.6 ± 1.0 L.min-1; upper body:lower body ratio: 87.2 ± 5.6%) performed four VO2Peak tests; one treadmill ski-striding test and three double poling ski-ergometer tests over five days. Test-retest reliability of the ski-ergometer protocol was determined for maximal oxygen consumption (VO2peak). The ski-ergometer test showed excellent reliability for VO2Peak (L.min-1) (coefficient of variation [CV] = 1.9%, 95% confidence limit [95% CL] [1.2, 4.7]; r = 1.00, [0.96, 1.00]) and UBPPeak (W) (CV = 1.4%, [0.9, 3.4]; r = 1.00, [0.97, 1.00]). Very strong correlations existed between the ski-ergometer and the ski-striding protocol for VO2Peak (r = 0.95, [0.76, 0.99]). The upper body ski-ergometer test provided valid and reliable measurements of ski-specific upper body aerobic power in well-trained male cross-country skiers

A contemporary understanding of iron metabolism in active premenopausal females

Iron metabolism research in the past decade has identified menstrual blood loss as a key contributor to the prevalence of iron deficiency in premenopausal females. The reproductive hormones estrogen and progesterone influence iron regulation and contribute to variations in iron parameters throughout the menstrual cycle. Despite the high prevalence of iron deficiency in premenopausal females, scant research has investigated female-specific causes and treatments for iron deficiency. In this review, we provide a comprehensive discussion of factors that influence iron status in active premenopausal females, with a focus on the menstrual cycle. We also outline several practical guidelines for monitoring, diagnosing, and treating iron deficiency in premenopausal females. Finally, we highlight several areas for further research to enhance the understanding of iron metabolism in this at-risk population

Peak match acceleration demands differentiate between elite youth and professional football players

Youth footballers need to be developed to meet the technical, tactical, and physical demands of professional level competition, ensuring that the transition between competition levels is successful. To quantify the physical demands, peak match intensities have been measured across football competition tiers, with team formations and tactical approaches shown to influence these physical demands. To date, no research has directly compared the physical demands of elite youth and professional footballers from a single club utilising common formations and tactical approaches. The current study quantified the total match and peak match running demands of youth and professional footballers from a single Australian A-League club. GPS data were collected across a single season from both a professional (n = 19; total observations = 199; mean ± SD; 26.7 ± 4.0 years) and elite youth (n = 21; total observations = 59; 17.9 ± 1.3 years) team. Total match demands and peak match running demands (1–10 min) were quantified for measures of total distance, high-speed distance [>19.8 km-h-1] and average acceleration. Linear mixed models and effect sizes identified differences between competition levels. No differences existed between competition levels for any total match physical performance metric. Peak total and high-speed distances demands were similar between competitions for all moving average durations. Interestingly, peak average acceleration demands were lower (SMD = 0.63–0.69) in the youth players across all moving average durations. The data suggest that the development of acceleration and repeat effort capacities is crucial in youth players for them to transition into professional competition

Iron supplementation and altitude: Decision making using a regression tree

[No abstract available

Hormonal contraceptive use in football codes in Australia

The recent launch of the new National elite women’s football competitions in Australia has seen a 20–50% increase in grassroots female participation. With the growing participation across grassroots to elite competitions, understanding the health of female athletes should be prioritized. In elite level athletes, hormonal contraceptive (HC) use is common (�50%), however, little is known about the prevalence and reasons for use and disuse of HC in elite female football athletes. As such, the impact of HC use is often not considered when monitoring the health of female footballers. This study involved a subset of data collected as part of a larger questionnaire investigating menstrual cycle function, hormonal contraception use, and the interaction with training load volume and perceived performance in elite female football code athletes. A total of 177 participants completed the questionnaire across three football codes within Australia (rugby league, rugby union/sevens, Australian football). One third (n = 58) of athletes were currently using HC, predominately in the form of an oral contraceptive pill (OC, n = 47). Reasons for use included: to avoid pregnancy (71%); to control/regulate cycle (38%); and to reduce menstrual pain (36%). However, most athletes using an OC (89%) could not identify the type of pill used (e.g., mono-, bi-, or triphasic). The main reason for disuse was due to the negative side effects (n = 23), such as mood swings, weight gain, and depression/anxiety. Comparing HC users and non-users, there were no statistical differences in the number of reported menstrual symptoms, use of medication to relieve menstrual pain, or frequency for needing to adapt training due to their menstrual cycle (p > 0.05). Since most athletes were unaware of the type of OC they used, female football athletes require further education about the different types of HC, and specifically OC, available to them. Similarities in the symptoms experienced, pain management, and training adaptation requirements between groups suggests that HC use may not have the intended outcome for certain athletes. As such, greater awareness of athlete’s personal experiences with the menstrual cycle, how HC may influence their experience, and acknowledgment of non-pharmacological methods to help manage menstrual cycle related symptoms are warranted

An Analysis of Warm-Up Strategies at a Cross-Country Skiing National Championship

Purpose: To provide a descriptive analysis of the warm-up (WU) strategies employed by cross-country skiers prior to distance and sprint competitions at a national championship and to compare the skiers’ planned and executed WUs prior to the respective competitions. Methods: Twenty-one national- and international-level skiers (11 women and 10 men) submitted WU plans prior to the distance and sprint competitions, and after the competitions, reported any deviations from the plans. Skiers used personal monitors to record heart rate (HR) during WU, races, and cooldown. Quantitative statistical analyses were conducted on WU durations, durations in HR-derived intensity zones, and WU loads. Qualitative analyses were conducted on skiers’ WU plans and their reasons for deviating from the plans. Results: Skiers’ planned WUs were similar in content and planned time in HR-derived intensity zones for both the distance and sprint competitions. However, 45% of the women and 20% of the men reported that their WU was not carried out as planned, with reasons detailed as being due to incorrect intensities and running out of time. WU activities including skiing across variable terrain, muscle-potentiating exercises, and heat-maintenance strategies were missing from the skiers’ planned routines. Conclusions: Skiers favored a long, traditional WU approach for both the sprint and distance events, performing less high-intensity and more moderate-intensity exercise during their WUs than planned. In addition, elements likely relevant to successful performance in cross-country skiing were missing from WU plans

Iron status and the acute post-exercise hepcidin response in athletes

This study explored the relationship between serum ferritin and hepcidin in athletes. Baseline serum ferritin levels of 54 athletes from the control trial of five investigations conducted in our laboratory were considered; athletes were grouped according to values 100 mg/L (SF\u3e100). Data pooling resulted in each athlete completing one of five running sessions: (1) 8x3 min at 85% vVO2peak; (2) 5x4 min at 90% vVO2peak; (3) 90 min continuous at 75% vVO2peak; (4) 40 min continuous at 75% vVO 2peak; (5) 40 min continuous at 65% vVO2peak. Athletes from each running session were represented amongst all four groups; hence, the mean exercise duration and intensity were not different (p\u3e0.05). Venous blood samples were collected pre-, post- and 3 h post-exercise, and were analysed for serum ferritin, iron, interleukin-6 (IL-6) and hepcidin-25. Baseline and post-exercise serum ferritin levels were different between groups (p0.05). Post-exercise IL-6 was significantly elevated compared to baseline within each group (p100;

Improving menstrual health literacy in sport

Menstrual health represents a state of complete physical, mental, and social well-being in relation to a woman's menstrual cycle. From a health literacy perspective, knowledge acquisition and expertise are dependent upon the degree to which an individual can find, access, understand, critically analyse, and apply health information. Therefore, menstrual health literacy (MHL) can be used to describe the state of knowledge acquisition and expertise specific to menstrual health-related issues. Menstrual health literacy is low among female athletes, their coaches, and practitioners, and few evidence-informed education or implementation strategies exist to improve MHL in sport. Moreover, athletes seldom discuss their menstrual cycles or hormonal contraceptive (HC) use with their coaches, despite experiencing menstrual symptoms and/or disturbances and perceiving their menstrual cycles/HC use to affect performance. Barriers to communication about menstrual cycle- and HC-related topics include a perceived lack of knowledge among athletes, coaches, and practitioners, concerns about how conversations on these issues will affect interpersonal relationships, and a lack of formal and informal discussion forums. While evidence relating to the effects of menstrual cycle phase and HC use on training and performance is currently limited, with existing studies often lacking methodological rigour, impactful steps can still be made to support female athletes. This cornerstone review highlights the current state of MHL among athletes, coaches, and practitioners, and provides recommendations for improving MHL in sport

Not as simple as it seems: Front foot contact kinetics, muscle function and ball release speed in cricket pace bowlers.

This study investigated the relationship between front foot contact (FFC) ground reaction forces (GRF) during the delivery stride, lower-limb strength, eccentric dexterity and power, and ball release speed (BRS) among pace bowlers. Thirteen high-level male pace bowlers performed double and single leg drop landings; isometric mid-thigh pull; countermovement jump; and pace bowling (two-over bowling spell measuring BRS and FFC GRF). The relationship between assessed variables and BRS was determined via frequentist and Bayesian multiple linear regression. The model including peak braking force was the most probable given the data (Bayes Factor=1.713) but provided only evidence in comparison to the null model. The results of frequentist and Bayesian modelling were comparable with peak braking force explaining 23.3% of the variance in BRS ( =4.64, =0.054). Results indicate pace bowlers with greater peak braking GRF during FFC generally elicit higher BRS. However, the weak relationship between peak braking force and BRS, and the lack of a linear relationship between BRS and other variables, highlights the complexities and inter-individual variability inherent to pace bowling at a high-level. A more individual-focused analysis revealed varied strategies within pace bowlers to deliver the outcome (e.g., BRS) and should be considered in future study designs