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 <30 μg/L (SF<30), 30-50 μg/L (SF30-50), 50-100 μg/L (SF50-100), or >100 μg/L (SF>100). Data pooling resulted in each athlete completing one of five running sessions: (1) 8 × 3 min at 85% vVO2peak; (2) 5 × 4 min at 90% vVO2peak; (3) 90 min continuous at 75% vVO2peak; (4) 40 min continuous at 75% vVO2peak; (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>0.05). 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 (p<0.05). There were no group differences for pre- or post-exercise serum iron or IL-6 (p>0.05). Post-exercise IL-6 was significantly elevated compared to baseline within each group (p<0.05). Pre- and 3 h post-exercise hepcidin-25 was sequentially greater as the groups baseline serum ferritin levels increased (p<0.05). However, post-exercise hepcidin levels were only significantly elevated in three groups (SF30-50, SF50-100, and SF>100; p<0.05). An athlete's iron stores may dictate the baseline hepcidin levels and the magnitude of post-exercise hepcidin response. Low iron stores suppressed post-exercise hepcidin, seemingly overriding any inflammatory-driven increases.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Micronutrients and athletic performance: A review Beck, Kathryn L.; von Hurst, Pamela R.; O'Brien, Wendy J. ...
Food and chemical toxicology,
December 2021, 2021-Dec, 2021-12-00, 20211201, Letnik:
158
Journal Article
Recenzirano
Optimising nutrition intake is a key component for supporting athletic performance and supporting adaption to training. Athletes often use micronutrient supplements in order to correct vitamin and ...mineral deficiencies, improve immune function, enhance recovery and or to optimise their performance. The aim of this review was to investigate the recent literature regarding micronutrients (specifically iron, vitamin C, vitamin E, vitamin D, calcium) and their effects on physical performance. Over the past ten years, several studies have investigated the impacts of these micronutrients on aspects of athletic performance, and several reviews have aimed to provide an overview of current use and effectiveness. Currently the balance of the literature suggests that micronutrient supplementation in well-nourished athletes does not enhance physical performance. Excessive intake of dietary supplements may impair the body's physiological responses to exercise that supports adaptation to training stress. In some cases, micronutrient supplementation is warranted, for example, with a diagnosed deficiency, when energy intake is compromised, or when training and competing at altitude, however these micronutrients should be prescribed by a medical professional. Athletes are encouraged to obtain adequate micronutrients from a wellbalanced and varied dietary intake.
•Athletes often use micronutrient supplements hoping to improve performance.•Most research does not support supplementation in well-nourished athletes.•Micronutrient supplementation may be associated with negative consequences.•Micronutrient supplementation may be needed in some cases eg. diagnosed deficiency.•Athletes are encouraged to eat a well-balanced and varied diet.
Background
Body-fluid loss during prolonged continuous exercise can impair cardiovascular function, harming performance. Delta percent plasma volume (
d
PV) represents the change in central and ...circulatory body-water volume and therefore hydration during exercise; however, the effect of carbohydrate–electrolyte drinks and water on the
d
PV response is unclear.
Objective
To determine by meta-analysis the effects of ingested hypertonic (> 300 mOsmol kg
−1
), isotonic (275–300 mOsmol kg
−1
) and hypotonic (< 275 mOsmol kg
−1
) drinks containing carbohydrate and electrolyte (Na
+
< 50 mmol L
−1
), and non-carbohydrate drinks/water (< 40 mOsmol kg
−1
) on
d
PV during continuous exercise.
Methods
A systematic review produced 28 qualifying studies and 68 drink treatment effects. Random-effects meta-analyses with repeated measures provided estimates of effects and probability of superiority (
p
+
) during 0–180 min of exercise, adjusted for drink osmolality, ingestion rate, metabolic rate and a weakly informative Bayesian prior.
Results
Mean drink effects on
d
PV were: hypertonic − 7.4% 90% compatibility limits (CL) − 8.5, − 6.3, isotonic − 8.7% (90% CL − 10.1, − 7.4), hypotonic − 6.3% (90% CL − 7.4, − 5.3) and water − 7.5% (90% CL − 8.5, − 6.4). Posterior contrast estimates relative to the smallest important effect (
d
PV = 0.75%) were: hypertonic-isotonic 1.2% (90% CL − 0.1, 2.6;
p
+
= 0.74), hypotonic-isotonic 2.3% (90% CL 1.1, 3.5;
p
+
= 0.984), water-isotonic 1.3% (90% CL 0.0, 2.5;
p
+
= 0.76), hypotonic-hypertonic 1.1% (90% CL 0.1, 2.1;
p
+
= 0.71), hypertonic-water 0.1% (90% CL − 0.8, 1.0;
p
+
= 0.12) and hypotonic-water 1.1% (90% CL 0.1, 2.0;
p
+
= 0.72). Thus, hypotonic drinks were very likely superior to isotonic and likely superior to hypertonic and water. Metabolic rate, ingestion rate, carbohydrate characteristics and electrolyte concentration were generally substantial modifiers of
d
PV.
Conclusion
Hypotonic carbohydrate–electrolyte drinks ingested continuously during exercise provide the greatest benefit to hydration.
Graphical abstract
Hepcidin, a peptide hormone with an acknowledged evolutionary function in iron homeostasis, was discovered at the turn of the 21st century. Since then, the implications of increased hepcidin activity ...have been investigated as a potential advocate for the increased risk of iron deficiency in various health settings. Such implications are particularly relevant in the sporting community where peaks in hepcidin postexercise (∼3-6 hr) are suggested to reduce iron absorption and recycling, and contribute to the development of exercise-induced iron deficiency in athletes. Over the last decade, hepcidin research in sport has focused on acute and chronic hepcidin activity following single and repeated training blocks. This research has led to investigations examining possible methods to attenuate postexercise hepcidin expression through dietary interventions. The majority of macronutrient dietary interventions have focused on manipulating the carbohydrate content of the diet in an attempt to determine the health of athletes adopting the low-carbohydrate or ketogenic diets, a practice that is a growing trend among endurance athletes. During the process of these macronutrient dietary intervention studies, an observable coincidence of increased cumulative hepcidin activity to low energy availability has emerged. Therefore, this review aims to summarize the existing literature on nutritional interventions on hepcidin activity, thus, highlighting the link of hepcidin to energy availability, while also making a case for the use of hepcidin as an individualized biomarker for low energy availability in males and females.
Iron deficiency is a common nutrient deficiency within athletes, with sport scientists and medical professionals recognizing that athletes require regular monitoring of their iron status during ...intense training periods. Revised considerations for athlete iron screening and monitoring have suggested that males get screened biannually during heavy training periods and females require screening biannually or quarterly, depending on their previous history of iron deficiency. The prevalence of iron deficiency in female athletes is higher than their male counterparts and is often cited as being a result of the presence of a menstrual cycle in the premenopausal years. This review has sought to revise our current understanding of female physiology and the interaction between primary reproductive hormones (oestrogen and progesterone) and iron homoeostasis in females. The review highlights an apparent symbiotic relationship between iron metabolism and the menstrual cycle that requires additional research as well as identifying areas of the menstrual cycle that may be primed for nutritional iron supplementation.
The purpose of this study was to determine the effects of pre-exercise amino acid (AA) supplementation on post-exercise iron regulation. Ten healthy males participated under two different sets of ...conditions in a randomized, double-blind, crossover design with a washout period of at least 21 days. Participants received either an AA supplement or placebo (PLA) for five consecutive days (4 g/dose, 3 doses/day). On the sixth day, participants ran on a treadmill for 60 min at 70% of maximal oxygen consumption (V˙O
). Venous blood samples were collected before (baseline), immediately after, and 1 and 3 h after exercise. The serum hepcidin levels increased significantly 3 h post-exercise in both trials when compared to the baseline (
< 0.001), but the levels were not different between trials. The plasma interleukin-6 (IL-6) level significantly increased immediately after exercise compared to the baseline (
< 0.001) and was significantly higher in the AA trial than in the PLA trial (
= 0.014). Moreover, the exercise-induced increase in serum glycerol level was significantly higher in the AA trial (21.20 ± 3.98 mg/L) than in the PLA trial (17.28 ± 4.47 mg/L,
= 0.017). No significant differences were observed between the AA and PLA trials for serum iron, ferritin, and total ketone body levels (
> 0.05). In conclusion, five days of AA supplementation augmented exercise-induced increases in IL-6 and glycerol in healthy males. However, it did not affect post-exercise iron status or regulation.
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.
Purpose
The purpose of this study was to determine the effects of 3 consecutive days of endurance training in hypoxia on hepcidin responses.
Method
Nine active healthy males completed two trials, ...consisting of 3 consecutive days of endurance training in either hypoxia fraction of inspired oxygen (F
i
O
2
): 14.5%) or normoxia (F
i
O
2
: 20.9%). On days 1–3, participants performed one 90 min session of endurance training per day, consisting of high-intensity endurance interval exercise 10 × 4 min of pedaling at 80% of maximal oxygen uptake (
V
˙
O
2max
) with 2 min of active rest at 30% of
V
˙
O
2max
followed by 30 min of continuous exercise at 60% of
V
˙
O
2max
. Venous blood samples were collected prior to exercise each day during the experimental period (days 1–4) to determine serum hepcidin, iron, ferritin, haptoglobin, and ketone body concentrations.
Result
Serum iron (
p
< 0.0001), ferritin (
p
= 0.005) and ketone body (
p
< 0.0001) concentrations increased significantly in both trials on days 2–4 compared with day 1, with no significant differences between trials. No significant changes in serum haptoglobin concentrations were observed throughout the experimental period in either trial. Serum hepcidin concentrations also increased significantly on days 2–4 compared with day 1 in both trials (
p
= 0.004), with no significant differences observed between trials.
Conclusion
3 consecutive days of endurance training in hypoxia did not affect hepcidin concentrations compared with endurance training in normoxia.
Purpose
To examine the effects of 24-h controlled carbohydrate intake on next day pre- and post-exercise inflammatory and hepcidin responses.
Methods
In a crossover design, 12 well-trained endurance ...athletes (Ht 181.08 ± 7.68 cm; Wt 74.8 ± 11.5 kg,
V
O
2peak
68.9 ± 7.2 ml kg
−1
min
−1
) completed two experimental (2-day) trials. On day 1, participants completed a glycogen depletion task, including a 16-km run (80 % v
V
O
2peak
) and 5 × 1 min efforts (130 % v
V
O
2peak
) separated by 2-min recovery. Subsequently, strict dietary control was enforced for 24 h, where low carbohydrate (LCHO 3 g kg
−1
) or high carbohydrate (HCHO 10 g kg
−1
) diets were provided. Twenty-four hours later, participants completed an 8 × 3 min interval running session at 85 % v
V
O
2peak
followed by 3-h monitored recovery. Venous blood samples were collected pre-, immediately post- and 3-h post-exercise, which were analyzed for interleukin-6, serum iron, ferritin and hepcidin.
Results
Interleukin-6 was elevated (
p
< 0.001) immediately post-exercise compared to baseline in both conditions, but was lower in HCHO (
p
= 0.015). Hepcidin levels were also lower at baseline (
p
= 0.049) in HCHO, and a large effect (
d
= 0.72) indicated a trend for lower levels at 3-h post-exercise compared to LCHO. Serum iron was increased post-exercise for both trials (
p
= 0.001), whereas serum ferritin remained unchanged.
Conclusions
Twenty-four hours of controlled low carbohydrate intake resulted in higher baseline hepcidin levels and post-exercise IL-6 responses than a high carbohydrate intake. Such hormone increases may be induced by gluconeogenic signaling of the liver, and may negatively impact an athlete’s iron metabolism.
Nutrition education (NE) is one of several strategies aimed at enhancing the dietary intake of athletes. This study investigated NE preferences of New Zealand and Australian athletes competing ...nationally and internationally. Athletes (
= 124, 22 (18, 27) years, female 54.8%) from 22 sports completed an online survey, with responses analysed using descriptive statistics. Teaching techniques considered 'extremely effective' were life examples (47.6% of athletes), hands-on activities (30.6%), and discussions with a facilitator (30.6%). Setting personal nutrition goals was important to most athletes (83.9%), along with two-way feedback with a facilitator (75.0%). General nutrition topics considered 'essential' were energy requirements (52.9%), hydration (52.9%), and nutrient deficiencies (43.3%). Performance topics considered 'essential' were recovery (58.1%), pre-exercise nutrition (51.6%), nutrition during exercise (50.0%), and energy requirements for training (49.2%). Athletes preferred a 'combination of in-person group and one-on-one sessions' (25% of athletes), 'one-on one sessions' (19.2%) and 'in-person group sessions' (18.3%), with only 13.3% interested in 'exclusively online delivery'. Sessions of 31-60 min (61.3% of athletes) held monthly (37.5%) and undertaken with athletes of the same sporting calibre (61.3%) were favoured by the participants. The preferred facilitator was a performance dietitian or nutritionist (82.1% of athletes), who had knowledge of the sport (85.5%), experience in sports nutrition (76.6%), and credibility (73.4%). This research provides novel insights into the factors that need to be considered when designing and implementing nutrition education for athletes.
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