Kinetics of Physiological Responses as a Measure of Intensity and Hydration Status During Experimental Physical Stress in Human Volunteers

Shirley W Kartaram,Laura M’Rabet,Renger Witkamp,Harriet Wittink,Marc Teunis,Marco Mensink,Karin Mohrmann,Raymond Pieters,Isolde Besseling-Van Der Vaart,Eric Schoen,Johan Garssen,Klaske Van Norren,Martie Verschuren

doi:10.3389/fphys.2020.01006

Abstract

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.

Highlights

Strenuous 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
We present a full overview and detailed analysis of the interaction between the kinetic responses of a wide range of physiological parameters measured in the same study
The study was registered at the ISRCTN clinical trial registry with code ISRCTN13656034, approved by the Medical Ethics Committee of Wageningen University and Research (WUR), Netherlands, and conducted in accordance with the Declaration of Helsinki (Fortaleza, Brazil, 2013)

Summary

Introduction

Strenuous 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 be used in an experimental set-up by measuring time-dependent changes in biomarkers for physiological processes. A recent definition describes health as ”the ability to adapt and to self-manage, in the face of social, physical and emotional challenges” (Huber et al, 2011). This concept implies that information on the health status of an individual can be inferred from the kinetics of a physiological or psychological response to a stressor. Suitable human test models to study resilience use different stressors, such as vaccination (to study immune responsiveness) (Petry et al, 1991; Michel et al, 1997), a test meal high in fat, carbohydrates or other nutrient combinations to study metabolic resilience (Wopereis et al, 2013; Kardinaal et al, 2015) or physical exercise (Lamprecht et al, 2012; JanssenDuijghuijsen et al, 2016, 2017a)

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