Iron Status and Homeostasis Across 2 Competitive Seasons in NCAA Division I Collegiate Cross-Country Runners Residing at Low Altitude.

PURPOSE: Inflammatory cytokines including interleukin-6 can upregulate hepcidin and decrease iron absorption. Endurance exercise is associated with transient increases in cytokines, which may alter the risk of iron deficiency (ID). This study examined whether chronic elevations in basal levels of cytokines and hepcidin were associated with ID in highly trained runners. METHODS: Fifty-four collegiate runners (26 males and 28 females) living at ∼1625 m were recruited from an NCAA Division I cross-country team for this prospective cohort study. Over 2 seasons, fasted, preexercise blood draws were performed in the morning 4 times per season and were analyzed for hemoglobin concentration, ferritin, soluble transferrin receptor (sTfR), hepcidin, and 10 cytokines. Stages of ID were defined using ferritin, sTfR, and hemoglobin concentration. During the study, a registered dietician provided all runners with iron supplements using athletic department-created guidelines. RESULTS: Fifty-seven percent of females and 35% of males exhibited stage 2 ID (ferritin <20 ng/mL or sTfR >29.5 nmol/L) at least once. Cytokines, ferritin, and sTfR exhibited changes through the 2 years, but changes in cytokines were not associated with alterations in hepcidin, ferritin, or sTfR. In males and females, lower ferritin was associated with lower hepcidin (both P < .0001). One female exhibited higher hepcidin and lower iron stores compared with other individuals, suggesting a different etiology of ID. CONCLUSION: ID is common in highly trained collegiate runners. In general, the high prevalence of ID in this population is not associated with alterations in basal hepcidin or cytokine levels.

ActivPAL accuracy in determining metabolic rate during walking, running and cycling.

To evaluate the ActivPAL's (AcP) ability to estimate METs during walking, running and cycling. Twenty physically active participants performed two submaximal exercises using a treadmill and cycle ergometer. The treadmill session involved varying speeds with a fixed grade and varying grade at fixed walking and running speeds. The cycling session involved fixed power, while cadence was varied and fixed cadence, while power was varied. Four AcPs (two AcP3 & two AcP4) were worn. ActivPAL MET estimations were compared to METS determined via indirect calorimetry. The AcP MET estimations between units and models did not differ. The AcP underestimated (-15% to -61%) METs with increasing speed and was unable to detect an increase in metabolic rate with a change in grade for walking and running. The AcP underestimated (-33% to -60%) METs during cycling and was unable to detect increases in metabolic rate when cadence was fixed, while power increased. The AcP can identify when exercise occurs and provides consistent information across units/models. However, the current AcP algorithm does not provide accurate estimates of METs during walking, running and cycling in a controlled laboratory setting, which would suggest limited accuracy in the field.

The importance of lean mass and iron deficiency when comparing hemoglobin mass in male and female athletic groups.

Hemoglobin mass (Hbmass) is important for athletes because it helps determine maximal aerobic power. This study examined how lean mass, iron deficiency (ID), and sex influence Hbmass in athletic and nonathletic groups. NCAA Division I student athletes (21 men, 75 women; altitude: 1,625 m) were recruited from six athletic teams; 14 male and 12 female full-time students (non-varsity athletes) served as control subjects. Hbmass, body composition, and iron homeostasis parameters, including ferritin, soluble transferrin receptor (sTfR), hepcidin, erythroferrone, and 10 inflammatory cytokines, were measured two to four times across a competitive/training season. ID was defined as ferritin < 25 ng/mL. Hbmass was more closely related to lean mass (r2 = 0.90) than body mass (r2 = 0.69, P < 0.01). Compared with female subjects, male subjects had 19.9% higher Hbmass relative to body mass (HbmassBM) but only 7.5% higher Hbmass relative to lean mass (HbmassLEAN) (both P < 0.001). Prevalence of ID was higher in female than male subjects (47% vs. 9%, P < 0.01) but did not vary between groups. HbmassLEAN was 5% lower in ID vs. non-ID female subjects; HbmassBM was not different. ID was associated with lower hepcidin, elevated sTfR, and elevated erythroferrone but not with differences in inflammatory cytokines. Hbmass varied significantly between athletic groups and across sex, but the majority of these differences are explained by differences in lean mass. ID was common in female subjects and was associated with lower HbmassLEAN and hepcidin but not with differences in HbmassBM or inflammatory cytokines. Hbmass relative to lean mass seems advantageous when monitoring iron deficiency.NEW & NOTEWORTHY Differences in hemoglobin mass (Hbmass) between groups and across sex are primarily due to differences in lean mass. Iron deficiency (ID) independently decreases Hbmass; this effect is best characterized with Hbmass relative to lean mass. ID is common in females and is associated with lower hepcidin and elevated erythroferrone but not with differences in inflammatory cytokines. Hbmass relative to lean mass accurately quantifies hematological alterations secondary to iron deficiency.

Breathing valve resistance alters physiological responses during a graded exercise test.

PURPOSE: To determine the impact of breathing valve resistance on peak aerobic capacity ([Formula: see text]) and running economy (RE) in endurance-trained and recreationally active individuals. METHODS: Ten endurance-trained males (ETM), 10 endurance-trained females (ETF), 10 recreationally active males (RAM), and 10 recreationally active females (RAF) participated in this study. On two separate occasions, subjects performed identical graded exercise treadmill protocols using either a Hans Rudolph 2700 (high resistance) or a Daniels' (low resistance) two-way non-rebreathing valve. Parameters obtained from these protocols included energy expenditure (EE), ventilation ([Formula: see text]), heart rate, respiratory exchange ratio, RE, [Formula: see text], and time to exhaustion (TTE). RESULTS: When using the Daniels' valve, all groups had lower submaximal EE (- 2.4, - 3.4, - 2.7, and - 2.0% for ETM, ETF, RAM, and RAF) and better RE (- 2.7, - 3.5, - 1.9, and - 1.8% for ETM, ETF, RAM and RAF) across all submaximal speeds. Only the ET groups had lower submaximal [Formula: see text] (4.6 and 3.8% for ETM and ETF) when using the Daniels' valve. TTE increased when using the Daniels' valve for all groups (6.0, 10.9, 6.2 and 9.8% for ETM, ETF, RAM and RAF), but [Formula: see text] was unaltered. CONCLUSION: Compared to the Daniels' valve, the Hans Rudolph 2700 valve altered the assessment of RE, submaximal EE, and TTE regardless of fitness level or sex, but did not change [Formula: see text]. Therefore, airflow resistance of a breathing valve must be considered when assessing and comparing EE, RE and TTE in the applied and research settings.

Stroke risk among patients with chronic obstructive pulmonary disease: A systematic review and meta-analysis.

Increased stroke risk among chronic obstructive pulmonary disease patients has not yet been established. In this study, we conducted a systematic review and meta-analysis to assess stroke risk among chronic obstructive pulmonary disease patients. PubMed, EMBASE, and the Cochrane Library were systematically searched from database inception until December 31, 2016 to identify longitudinal observational studies that investigated the association between chronic obstructive pulmonary disease and stroke. Stroke risk was quantified by overall and subgroup analyses, and a pooled hazard ratio was calculated. Study quality was evaluated using the Newcastle-Ottawa Scale. Publication bias was assessed using Begg's rank correlation test. Eight studies met the inclusion criteria. In a random-effects model, significantly increased stroke risk was observed among chronic obstructive pulmonary disease patients (hazard ratio, 1.30; 95% confidence interval, 1.18-1.43). In subgroup analyses stratified by stroke subtype, study quality, and adjustment by socioeconomic status, the association between increased stroke risk and chronic obstructive pulmonary disease patients was robust. Statistically significant publication bias was not detected. In summary, chronic obstructive pulmonary disease was found to be associated with increased stroke risk. Additional prospective studies are required to elucidate the mechanisms underlying the increase in stroke risk and identify effective preventive interventions.

The relationship between pulmonary function and suicidal ideation in Korean adults: a nationwide survey.

Controversy surrounds the association between lung function and mental health in the general population, and previous reported results were confounded by the effect of other chronic illnesses. This study aimed to investigate whether reduced lung function was related to mental health issues, taking into consideration the relevant potential confounders. We used data from the 2008-2013 Korean National Health and Nutrition Examination Survey to examine the relationship between lung function and three mental issues (recognized stress, depressive mood, and suicidal ideation) among 22,068 Korean adults. A multiple logistic regression with adjustment for potential covariates including chronic illnesses revealed that a .5-L decrement of forced vital capacity increased the risk for suicidal ideation in both genders, but there was no significant association with recognized stress or depressive mood. We found an inverse relationship between lung function and suicidal ideation in the Korean general population.

Stroke risk among patients with chronic obstructive pulmonary disease: A systematic review and meta-analysis

Increased stroke risk among chronic obstructive pulmonary disease patients has not yet been established. In this study, we conducted a systematic review and meta-analysis to assess stroke risk among chronic obstructive pulmonary disease patients. PubMed, EMBASE, and the Cochrane Library were systematically searched from database inception until December 31, 2016 to identify longitudinal observational studies that investigated the association between chronic obstructive pulmonary disease and stroke. Stroke risk was quantified by overall and subgroup analyses, and a pooled hazard ratio was calculated. Study quality was evaluated using the Newcastle-Ottawa Scale. Publication bias was assessed using Begg's rank correlation test. Eight studies met the inclusion criteria. In a random-effects model, significantly increased stroke risk was observed among chronic obstructive pulmonary disease patients (hazard ratio, 1.30; 95% confidence interval, 1.18-1.43). In subgroup analyses stratified by stroke subtype, study quality, and adjustment by socioeconomic status, the association between increased stroke risk and chronic obstructive pulmonary disease patients was robust. Statistically significant publication bias was not detected. In summary, chronic obstructive pulmonary disease was found to be associated with increased stroke risk. Additional prospective studies are required to elucidate the mechanisms underlying the increase in stroke risk and identify effective preventive interventions.