Influence of physical training on intracellular and extracellular zinc concentrations

Evaluation of imprecision in the different detection methods of Zn based on 5 years of data from an external quality assessment program in China

BACKGROUND

This study examines the imprecision of zinc (Zn) measurements across various clinical detection methods by analyzing the external quality assessment (EQA) data from 2018 to 2022. The findings of this study aim to offer recommendations for enhancing Zn measurements.

METHODS

Participating laboratories were grouped into peer categories based on the detection methods. The robust mean and coefficient of variation (CV) of the samples were calculated following ISO 13528 guidelines. The evaluation criteria for optimal, desirable, and minimum allowable imprecision in Zn estimation are 2.50%, 5.05%, and 7.55%, respectively, based on biological variation. Furthermore, the study examined inter-lab CVs, inter-method bias, and the passing rate. The impact of sample concentration on CVs and the pass rate was also investigated.

RESULTS

Over the past five years, 4283 laboratories participated in the EQA program, showing a high pass rate that improved as sample concentration increased. Differential pulse polarography (DPP) demonstrated stable and low CVs (0.61-1.86%). Although differential pulse stripping (DPS) was less stable than DPP, it still exhibited a low CV (0.71-3.10%). Graphite furnace atomic absorption spectrometry (GFAAS) and flame atomic absorption spectrometry (FAAS) performed similarly and displayed stable CVs (2.39-4.42%) within the acceptable range of desirable imprecision (5.05%). However, the CVs for ICP-MS were unacceptable in three out of the five years (5.28-6.20%). In 2022, the number of participating laboratories for DDP, DPS, GFAAS, FAAS and ICP-MS is 131, 35, 35, 820 and 72, respectively.

CONCLUSION

This study provides reliable insights into the imprecision of Zn measurements in clinical laboratories. The findings indicate that additional efforts are required to reduce the imprecision of ICP-MS in Zn measurements.

Zinc transporters expression profile in professional handball players supplemented with zinc

INTRODUCTION

Zinc (Zn) deficiency has been described not only on general human health but also within the sports context -as negatively affecting performance-. Thus, Zn status assessment is of great interest for athletes, especially in order to correct deficiency states of this mineral.

OBJECTIVE

The overall objective of this work was to assess Zn status in professional handball players during the competitive period (through plasma levels, dietary intake and gene expression of the Zn transporters), as well as to determine the effect of Zn supplementation.

METHODS

A total of twenty-two participants were recruited, -twelve belonged to the Control Group (CG) and ten male handball players comprised the experimental group (ATH-G)-, being monitored over a 2-month period with 2 evaluation moments: baseline (i.e., initial conditions) and follow-up (i.e., after 8 weeks of training and competition). Zn intake, plasma Zn levels, and gene expression of Zn transporters were obtained.

RESULTS

Plasma Zn levels were higher in ATH-G than in CG at the end of Zn intervention (p ≤ 0.010). Moreover, differences in the gene expression profile of Zn transporters were observed in ATH-G -with the down-regulation of several Zn transporters-, compared to the CG at baseline (p ≤ 0.05). Likewise, differences in the Zn transporters expression were observed in ATH-G at 8 weeks (all, p ≤ 0.001) -with ZnT2, ZnT5, ZIP3, ZIP5, ZIP11, ZIP13 and ZIP14 transporters being up-regulated-.

CONCLUSION

Handball players seemed to have different nutritional needs for Zn, with differences in the gene expression of Zn transporters compared to controls. Zn intervention in our athletes may have influenced the expression of Zn transporters, indicating a potential increase in Zn transporters expression to mobilize Zn at the cellular level at 8 weeks of Zn intervention.

Sex differences in cadmium and lead concentrations in different biological matrices in athletes. Relationship with iron status

PURPOSE

The present study aimed to analyse sex differences in cadmium and lead concentrations in plasma, urine, platelets and erythrocytes and to relate these concentrations to biomarkers of iron status.

METHODS

A total of 138 soccer players divided according to sex: men (n = 68) and women (n = 70) participated in the present study. All participants resided in the city of Cáceres (Spain). Erythrocyte, haemoglobin, platelet, plateletcrit, ferritin and serum iron values were determined. Cadmium and lead concentrations were quantified by inductively coupled plasma mass spectrometry.

RESULTS

The women had lower haemoglobin, erythrocyte, ferritin and serum iron values (p < 0.01). Regarding cadmium, the women showed higher concentrations in plasma, erythrocytes and platelets (p < 0.05). As for lead, they also showed higher concentrations in plasma, relative values of erythrocytes and relative values of platelets (p < 0.05). Significant correlations were observed between cadmium and lead concentrations with biomarkers of iron status.

CONCLUSIONS

Cadmium and lead concentrations are different between sexes. Biological differences between sexes and iron status could influence cadmium and lead concentrations. Lower serum iron concentrations and markers of Fe status increase Cd and Pb concentrations. Ferritin and serum iron have been directly related to increased Cd and Pb excretion.

Extracellular and Intracellular Concentrations of Molybdenum and Zinc in Soccer Players: Sex Differences

Molybdenum (Mo) and zinc (Zn) play important roles in the process of adaptation to physical training. The aims of the present study were: (i) to analyze the differences in extracellular (plasma and urine) and intracellular (erythrocytes and platelets) Mo and Zn concentrations between sexes and (ii) to relate extracellular Zn concentrations with biomarkers of muscle damage and muscle mass. The present study involved 138 semi-professional soccer players divided according to sex: male (n = 68) and female (n = 70). Mo and Zn concentrations were determined by inductively coupled plasma mass spectrometry. Erythrocytes, platelets, creatine kinase (CK), and lactate dehydrogenase (LDH) values were also determined by automatic cell counter and spectrophotometric techniques. There were no sex differences in Mo and Zn intake. Male soccer players obtained higher values of erythrocytes, CK, and LDH (p < 0.05), and showed higher plasma and urinary concentrations of Mo and Zn (p < 0.05). Female soccer players showed relatively higher Zn concentrations in erythrocytes (p < 0.05). Finally, positive correlations were observed between extracellular Zn concentrations with CK, LDH and muscle mass. Extracellular concentrations of Mo and Zn were higher in male soccer players. However, the relative concentrations of Zn in relation to the number of erythrocytes were higher in female soccer players.

Total Iron Concentrations in Different Biological Matrices-Influence of Physical Training

Iron (Fe) is one of the most widely studied trace mineral elements. Fe metabolism and homeostasis could be altered by physical training. The aim of this study was to analyze the influence of long-term physical training on serum, plasma, urine (extracellular), erythrocyte and platelet (intracellular) Fe concentrations. Forty men from the same geographical area divided into a training group (TG; n = 20; 18.15 ± 0.27 years) and a control group (CG; n = 20; 19.25 ± 0.39 years) participated in this study. The TG was composed of soccer players of the highest youth category. The CG consisted of young people who did not follow any training routine and had not practiced any sport for at least the previous six months. The TG showed higher plasma and serum Fe concentrations (p < 0.05), but lower concentrations in erythrocytes and platelets compared to the CG (p < 0.01). Due to the differences observed in the extracellular and intracellular compartments, it seems necessary to perform a global Fe analysis to assess Fe status.

Analysis of Intracellular and Extracellular Selenium Concentrations: Differences According to Training Level

Trace mineral element concentrations are under homeostatic control. Selenium (Se) is a very important micronutrient for the antioxidant and immune system. Se metabolism could be modified due to physical training. This research aimed to analyze the extracellular (plasma, urine and serum) and intracellular (platelets and erythrocytes) concentrations of Se in athletes and to compare it with subjects with low levels of physical training. Forty young men divided into a control group (CG; n = 20; 19.25 ± 0.39 years) and a training group (TG; n = 20; 18.15 ± 0.27 years) participated in this study. The TG was formed by semi-professional soccer players. The analysis of Se was determined by inductively coupled plasma mass spectrometry. The TG obtained higher values of maximum oxygen consumption and muscle percentage (p < 0.05). The TG showed reduced absolute (p < 0.01) and relative (p < 0.05) Se concentrations in erythrocytes and platelets in comparison to CG. Trace element assessments should not be limited only to extracellular compartments as there could be deficiencies at the intracellular level.