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Effect of low energy availability during three consecutive days of endurance training on iron metabolism in male long distance runners.

ABSTRACT: We investigated the effect of low energy availability (LEA) during three consecutive days of endurance training on muscle glycogen content and iron metabolism. Six male long distance runners completed three consecutive days of endurance training under LEA or neutral energy availability (NEA) conditions. Energy availability was set at 20 kcal/kg fat-free mass (FFM)/day for LEA and 45 kcal/kg FFM/day for NEA. The subjects ran for 75 min at 70% of maximal oxygen uptake ( V? O2max ) on days 1-3. Venous blood samples were collected following an overnight fast on days 1-4, immediately and 3 hr after exercise on day 3. The muscle glycogen content on days 1-4 was evaluated by carbon-magnetic resonance spectroscopy. In LEA condition, the body weight and muscle glycogen content on days 2-4, and the FFM on days 2 and 4 were significantly lower than those on day1 (p < .05 vs. day1), whereas no significant change was observed throughout the training period in NEA condition. On day 3, muscle glycogen content before exercise was negatively correlated with serum iron level (immediately after exercise, 3 hr after exercise), serum hepcidin level immediately after exercise, and plasma IL-6 level immediately after exercise (p < .05). Moreover, serum hepcidin level on day 4 was significantly higher in LEA condition than that in NEA condition (p < .05). In conclusion, three consecutive days of endurance training under LEA reduced the muscle glycogen content with concomitant increased serum hepcidin levels in male long distance runners.

SUBMITTER: Ishibashi A

PROVIDER: S-EPMC7322269 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Effect of low energy availability during three consecutive days of endurance training on iron metabolism in male long distance runners.

Ishibashi Aya A Kojima Chihiro C Tanabe Yoko Y Iwayama Kaito K Hiroyama Tsutomu T Tsuji Toshiki T Kamei Akiko A Goto Kazushige K Takahashi Hideyuki H

Physiological reports 20200601 12

We investigated the effect of low energy availability (LEA) during three consecutive days of endurance training on muscle glycogen content and iron metabolism. Six male long distance runners completed three consecutive days of endurance training under LEA or neutral energy availability (NEA) conditions. Energy availability was set at 20 kcal/kg fat-free mass (FFM)/day for LEA and 45 kcal/kg FFM/day for NEA. The subjects ran for 75 min at 70% of maximal oxygen uptake ( V˙ O<sub>2max</sub> ) on da ...[more]

PMID: 32597030

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Project description:BackgroundLow energy availability (EA) can be detrimental for athlete health. Currently, it is not known what the threshold for low EA in men is, and what effects it may have on performance.MethodsThis study was set to determine potential effects of low EA by modulating male participants' exercise energy expenditure and controlling energy intake and consequently manipulating EA in three progressive stages (reducing EA by 25%%, and 75 %). Performance was measured with three specific tests for explosive power, endurance, and agility. Blood was drawn, resting energy expenditure was monitored and two questionnaires were repetitively used to address any changes in eating behaviors and well-being.ResultsRepeated measured design showed poorer performance (power output 391.82 ± 29.60 vs. 402.5 ± 40.03 W, p = 0.001; relative power output 5.53 ± 0.47 vs. 5.60 ± 0.47 W/kg, p = 0.018; explosive power 0.28 ± 0.04 vs. 0.32 ± 0.05 m, p = 0.0001, lactate concentration 7.59 ± 2.29 vs 10.80 ± 2.46 mmol/L, p = 0.001). the quartile range for testosterone was lower (2.33 ± 1.08 vs. 2.67 ± 0.78, p = 0.026) and there was a tendency for lower triiodothyronine (4.15 ± 0.61 vs. 4.46 ± 0.54 pmol/L, p = 0.072). Eating behaviors and well-being were worse (46.64 ± 7.55 vs. 24.58 ± 7.13, p = 0.011 and 15.18 ± 2.44 vs. 17.83 ± 3.54, p = 0.002). The intervention also resulted in lower body fat (8.44 ± 3.15 vs. 10.2 ± 2.5%, p = 0.013).ConclusionsAnalysis showed that most of the negative effects occurred in the range of 9-25 kCal·kg∙FFM·d-1. This is the range where we suggest a threshold for LEA in men could be. Reducing EA impaired explosive power first, then endurance. It was associated with a reduction in testosterone, triiodothyronine and there was a tendency for reduced IGF-1, but hormones were more resilient to changes in EA. Psychological assessment of eating behaviors and well-being proved to be very useful, whereas monitoring resting energy expenditure did not.

Project description:Endurance exercise is associated with a transient increase in neutrophil counts in the peripheral blood. Here we investigate the impact of intensified endurance exercise on the neutrophil compartment. We hypothesized that intensified endurance exercise leads to mobilization of neutrophil subsets, which are normally absent in the blood. Furthermore, we followed the potential build-up of neutrophil activation and the impact on overnight recovery of the neutrophil compartment during a seven-day cycling tour. The neutrophil compartment was studied in 28 healthy amateur cyclists participating in an eight-day strenuous cycling tour. Blood samples were taken at baseline, after 4 days and after 7 days of cycling. The neutrophil compartment was analyzed in terms of numbers and its phenotype by deep phenotyping of flow cytometry data with the multi-dimensional analysis method FLOOD. Repeated endurance exercise led to a gradual increase in total neutrophil counts over the days leading to a 1.26 fold-increase (95%CI 1.01-1.51 p = 0.0431) in the morning of day 8. Flow cytometric measurements revealed the appearance of 2 additional neutrophil subsets: CD16brightCD62Ldim and CD16dimCD62Lbright. A complex change in neutrophil phenotypes was present characterized by decreased expression of both CD11b and CD62L and marked increased expression of LAIR-1, VLA-4 and CBRM1/5. The changes in expression were found on all neutrophils present in the blood. Strikingly, in strong contrast to our findings during acute inflammation evoked by LPS challenge, these neutrophils did not upregulate classical degranulation markers. In fact, our FLOOD analysis revealed that the exercise induced neutrophil phenotype did not overlap with the neutrophil subsets arising upon acute inflammation. In conclusion, during multiple days of endurance exercise the neutrophil compartment does not regain homeostasis overnight. Thereby our study supports the concept of a build-up of inflammatory cues during repeated endurance exercise training, causing a prolonged change of the systemic neutrophil compartment.

Dataset Information

Effect of low energy availability during three consecutive days of endurance training on iron metabolism in male long distance runners.

Publications

Effect of low energy availability during three consecutive days of endurance training on iron metabolism in male long distance runners.

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