Plasma/Serum Zinc Status During Aerobic Exercise Recovery: A Systematic Review and Meta-Analysis.
BACKGROUND
Exercise and the subsequent recovery processes have been proposed to induce disturbances in zinc homeostasis. We previously reported acute increase in serum zinc concentration immediately after aerobic exercise; the change in the indices of zinc status during exercise recovery was not explored.


OBJECTIVE
The aim of the current analysis is to determine the changes in zinc biomarkers during recovery from an aerobic exercise bout.


METHODS
We conducted a systematic literature search on PubMed, Web of Science, Scopus and SPORTDiscus electronic databases from inception to 20 December 2014 to identify studies that investigated the acute effects of exercise on selected indices of zinc status. Meta-analyses were conducted to determine the change in serum zinc concentration during exercise recovery, defined as up to 4 h following exercise cessation, compared to pre-exercise levels.


RESULTS
Forty-five studies were included in the systematic literature review, of which 12 studies (providing 18 comparisons) reported serum zinc levels after the cessation of exercise. During exercise recovery, serum zinc concentration was significantly lower than pre-exercise values (-1.31 ± 0.22 μmol/L, P < 0.001; mean ± SE). Secondary analyses showed a significant decrease of serum zinc levels in all categories of participants' training status, mode of exercise and time of blood collection. Insufficient data were available for meta-analysis of other zinc biomarkers.


CONCLUSIONS
The present analysis showed that serum zinc levels decrease significantly during exercise recovery, compared to pre-exercise levels. This extends our previous report of an increase in serum zinc immediately after exercise. We postulate that the exercise-induced fluctuations in zinc homeostasis are linked to the muscle repair mechanisms following exercise; the potential for zinc to enhance the exercise recovery process remains to be determined.
Department of Human Nutrition, University of Otago, PO Box 56, Dunedin, 9054, New Zealand.
Anna
A
Chu
Department of Statistics, Macquarie University, Sydney, NSW, Australia.
Peter
P
Petocz
Department of Human Nutrition, University of Otago, PO Box 56, Dunedin, 9054, New Zealand. samir.samman@otago.ac.nz.|Discipline of Nutrition and Metabolism, School of Molecular Bioscience, University of Sydney, Sydney, NSW, Australia. samir.samman@otago.ac.nz.
Samir
S
Samman
D015444:Exercise / Q000502:physiology*; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D015032:Zinc / Q000097:blood* / Q000378:metabolism
D015032:Zinc