The Impact of Endurance Exercise on Routine Laboratory Parameters in Young Trained Individuals

Abstract

Background: Endurance effort aims to improve aerobic capacity. During physical exertion, fluid shifts from intravascular to interstitial spaces, affecting potential conclusions from laboratory test results. The study aimed to assess the effects of endurance exercise on clinical interpretations of routine laboratory hematological and biochemical diagnostic tests. Methods: Participants were young, healthy, and physically active men aged 16-36 and women aged 16-29, who performed progressive treadmill tests to exhaustion. Blood samples were collected before the test, immediately after the test, and after 17 h of recovery. Results: The results showed that endurance exercise led to transient increases in the number of peripheral blood leukocytes and their subpopulations. A direct biological effect of endurance effort was an increase in the activity of amylase, AST, ALT, CK, GGT, LDH, and ALP, as well as in the concentration of creatinine, urea, uric acid, glucose, albumin, total protein, total cholesterol, HDL, triglycerides, sodium, chloride, phosphorus, and iron. Decreases in potassium and calcium (total and ionized) concentrations were also observed. Conclusions: The analyses clearly showed that laboratory tests performed in highly trained individuals may provide interpretation difficulties, and the reference ranges generally accepted in the healthy population might not apply to athletes.

Keywords: blood morphology; clinical biochemistry; exercise biochemistry; laboratory medicine; physical effort.

Figure 1

Study design model (Created in BioRender; https://BioRender.com/7ezeeal; accessed on 26 June 2025).

Figure 2

Plasma concentrations of (A) total protein, (B) albumin, and (C) C-reactive protein (CRP) in analyzed participants. Post effort’, recovery’ - values corrected for hemoconcentration. pMW: p-values for differences observed between men and women assessed using the Mann–Whitney U-test. Significance levels of differences observed between analyzed time points (baseline vs. post-effort vs. recovery) were assessed using Friedman’s analysis of variance, followed by post-hoc Dunn’s test with Bonferroni correction (Friedman’s ANOVA p values for each analysis were <0.001). Post-hoc p values: ^a p < 0.05, ^aa p < 0.01, and ^aaa p < 0.001 for baseline vs. post-effort; ^bbb p < 0.001 for post-effort vs. recovery; ^ccc p < 0.001 for recovery vs. baseline; ^a’a’ p < 0.01, and ^a’a’a’ p < 0.001 for baseline vs. post-effort values corrected for hemoconcentration; ^b’b’ p < 0.01, and ^b’b’b’ p < 0.001 for post-effort vs. recovery values corrected for hemoconcentration; ^c’c’ p < 0.01 for post-effort vs. recovery values corrected for hemoconcentration.

Figure 3

The plasma activity of (A) aspartate aminotransferase (AST), (B) alanine aminotransferase (ALT), (C) gamma-glutamyltransferase (GGTP), (D) lactate dehydrogenase (LDH), (E) amylase, (F) creatine kinase (CK), and (G) alkaline phosphatase (ALP) in analyzed participants. Post effort’, recovery’ - values corrected for hemoconcentration. pMW: p-values for differences observed between men and women assessed using the Mann–Whitney U-test. Significance levels of differences observed between analyzed time points (baseline vs. post-effort vs. recovery) were assessed using Friedman’s analysis of variance, followed by post-hoc Dunn’s test with Bonferroni correction (Friedman’s ANOVA p values for each analysis were <0.001). Post-hoc p values: ^aa p < 0.01 and ^aaa p < 0.001 for baseline vs. post-effort; ^bb p < 0.01 and ^bbb p < 0.001 for post-effort vs. recovery; ^c p < 0.05, ^cc p < 0.01, and ^ccc p < 0.001 for recovery vs. baseline; ^a’a’ p < 0.01, and ^a’a’a’ p < 0.001 for baseline vs. post-effort values corrected for hemoconcentration; ^b’b’ p < 0.01, and ^b’b’b’ p < 0.001 for post-effort vs. recovery values corrected for hemoconcentration; ^c’ p < 0.05, ^c’c’ p < 0.01, and ^c’c’c’ p < 0.001 for post-effort vs. recovery values corrected for hemoconcentration.

Figure 3

The plasma activity of (A) aspartate aminotransferase (AST), (B) alanine aminotransferase (ALT), (C) gamma-glutamyltransferase (GGTP), (D) lactate dehydrogenase (LDH), (E) amylase, (F) creatine kinase (CK), and (G) alkaline phosphatase (ALP) in analyzed participants. Post effort’, recovery’ - values corrected for hemoconcentration. pMW: p-values for differences observed between men and women assessed using the Mann–Whitney U-test. Significance levels of differences observed between analyzed time points (baseline vs. post-effort vs. recovery) were assessed using Friedman’s analysis of variance, followed by post-hoc Dunn’s test with Bonferroni correction (Friedman’s ANOVA p values for each analysis were <0.001). Post-hoc p values: ^aa p < 0.01 and ^aaa p < 0.001 for baseline vs. post-effort; ^bb p < 0.01 and ^bbb p < 0.001 for post-effort vs. recovery; ^c p < 0.05, ^cc p < 0.01, and ^ccc p < 0.001 for recovery vs. baseline; ^a’a’ p < 0.01, and ^a’a’a’ p < 0.001 for baseline vs. post-effort values corrected for hemoconcentration; ^b’b’ p < 0.01, and ^b’b’b’ p < 0.001 for post-effort vs. recovery values corrected for hemoconcentration; ^c’ p < 0.05, ^c’c’ p < 0.01, and ^c’c’c’ p < 0.001 for post-effort vs. recovery values corrected for hemoconcentration.

Figure 4

The plasma concentrations of (A) triglyceride (TG), (B) total cholesterol (TC), (C) high-density lipoprotein cholesterol (Ch-HDL), and (D) low-density lipoprotein (Ch-LDL) in analyzed participants. Post effort’, recovery’ - values corrected for hemoconcentration. pMW: p-values for differences observed between men and women assessed using the Mann–Whitney U-test. Significance levels of differences observed between analyzed time points (baseline vs. post-effort vs. recovery) were assessed using Friedman’s analysis of variance, followed by post-hoc Dunn’s test with Bonferroni correction (Friedman’s ANOVA p values for each analysis were <0.001). Post-hoc p values: ^a p < 0.05, ^aa p < 0.01, and ^aaa p < 0.001 for baseline vs. post-effort; ^bbb p < 0.001 for post-effort vs. recovery; ^c p < 0.05, ^cc p < 0.01, and ^ccc p < 0.001 for recovery vs. baseline; ^a’ p < 0.05, and ^a’a’a’ p < 0.001 for baseline vs. post-effort values corrected for hemoconcentration; ^b’ p < 0.05, and ^b’b’b’ p < 0.001 for post-effort vs. recovery values corrected for hemoconcentration; ^c’ p < 0.05, ^c’c’ p < 0.01, and ^c’c’c’ p < 0.001 for post-effort vs. recovery values corrected for hemoconcentration.

Figure 5

Plasma concentrations of (A) creatinine, (B) urea, (C) total bilirubin, (D) direct bilirubin, and (E) uric acid (UA) in analyzed participants. Post effort’, recovery’—values corrected for hemoconcentration. pMW: p-values for differences observed between men and women assessed using the Mann–Whitney U-test. Significance levels of differences observed between analyzed time points (baseline vs. post-effort vs. recovery) were assessed using Friedman’s analysis of variance, followed by post-hoc Dunn’s test with Bonferroni correction (Friedman’s ANOVA p values for each analysis were <0.001). Post-hoc p values: ^a p < 0.05, ^aa p < 0.01, and ^aaa p < 0.001 for baseline vs. post-effort; ^b p < 0.05 and ^bbb p < 0.001 for post-effort vs. recovery; ^c p < 0.05, ^cc p < 0.01, and ^ccc p < 0.001 for recovery vs. baseline; ^a’ p < 0.05, ^a’a’ p < 0.01, and ^a’a’a’ p < 0.001 for baseline vs. post-effort values corrected for hemoconcentration; ^b’ p < 0.05, and ^b’b’b’ p < 0.001 for post-effort vs. recovery values corrected for hemoconcentration; ^c’c’ p < 0.01, and ^c’c’c’ p < 0.001 for post-effort vs. recovery values corrected for hemoconcentration.

Figure 6

Calculated osmolalities in analyzed participants. Post effort’, recovery’ - values corrected for hemoconcentration. pMW: p-values for differences observed between men and women assessed using the Mann–Whitney U-test. Significance levels of differences observed between analyzed time points (baseline vs. post-effort vs. recovery) were assessed using Friedman’s analysis of variance, followed by post-hoc Dunn’s test with Bonferroni correction (Friedman’s ANOVA p values for each analysis were <0.001). Post-hoc p values: ^aaa p < 0.001 for baseline vs. post-effort; ^bbb p < 0.001 for post-effort vs. recovery; ^a’a’a’ p < 0.001 for baseline vs. post-effort values corrected for hemoconcentration; ^b’b’b’ p < 0.001 for post-effort vs. recovery values corrected for hemoconcentration; ^c’ p < 0.05, and ^c’c’c’ p < 0.001 for post-effort vs. recovery values corrected for hemoconcentration.