%A Kartaram,Shirley W. %A van Norren,Klaske %A Schoen,Eric %A Teunis,Marc %A Mensink,Marco %A Verschuren,Martie %A M’Rabet,Laura %A Besseling-van der Vaart,Isolde %A Mohrmann,Karin %A Wittink,Harriet %A Garssen,Johan %A Witkamp,Renger %A Pieters,Raymond %D 2020 %J Frontiers in Physiology %C %F %G English %K Kinetics,biomarkers,exercise-intensity,resilience,physiological responses,Dehydration %Q %R 10.3389/fphys.2020.01006 %W %L %M %P %7 %8 2020-September-04 %9 Original Research %# %! Kinetics of exercise-induced physiological responses %* %< %T Kinetics of Physiological Responses as a Measure of Intensity and Hydration Status During Experimental Physical Stress in Human Volunteers %U https://www.frontiersin.org/articles/10.3389/fphys.2020.01006 %V 11 %0 JOURNAL ARTICLE %@ 1664-042X %X IntroductionStrenuous physical stress induces a range of physiological responses, the extent depending, among others, on the nature and severity of the exercise, a person’s training level and overall physical resilience. This principle can also be used in an experimental set-up by measuring time-dependent changes in biomarkers for physiological processes. In a previous report, we described the effects of workload delivered on a bicycle ergometer on intestinal functionality. As a follow-up, we here describe an analysis of the kinetics of various other biomarkers.AimTo analyse the time-dependent changes of 34 markers for different metabolic and immunological processes, comparing four different exercise protocols and a rest protocol.MethodsAfter determining individual maximum workloads, 15 healthy male participants (20–35 years) started with a rest protocol and subsequently performed (in a cross-over design with 1-week wash-out) four exercise protocols of 1-h duration at different intensities: 70% Wmax in a hydrated and a mildly dehydrated state, 50% Wmax and intermittent 85/55% Wmax in blocks of 2 min. Perceived exertion was monitored using the Borg’ Rating of Perceived Exertion scale. Blood samples were collected both before and during exercise, and at various timepoints up to 24 h afterward. Data was analyzed using a multilevel mixed linear model with multiple test correction.ResultsKinetic changes of various biomarkers were exercise-intensity-dependent. Biomarkers included parameters indicative of metabolic activity (e.g., creatinine, bicarbonate), immunological and hematological functionality (e.g., leukocytes, hemoglobin) and intestinal physiology (citrulline, intestinal fatty acid-binding protein, and zonulin). In general, responses to high intensity exercise of 70% Wmax and intermittent exercise i.e., 55/85% Wmax were more pronounced compared to exercise at 50% Wmax.ConclusionHigh (70 and 55/85% Wmax) and moderate (50% Wmax) intensity exercise in a bicycle ergometer test produce different time-dependent changes in a broad range of parameters indicative of metabolic activity, immunological and hematological functionality and intestinal physiology. These parameters may be considered biomarkers of homeostatic resilience. Mild dehydration intensifies these time-related changes. Moderate intensity exercise of 50% Wmax shows sufficient physiological and immunological responses and can be employed to test the health condition of less fit individuals.