ASSESSMENT OF HEART RATE, PULMONARY AND MUSCULAR V’O2-KINETICS OF UPPER AND LOWER BODY EXERCISE DURING DYNAMIC MODERATE WORK RATE CHANGES

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Introduction
During dynamic work rate changes the kinetics of heart rate and pulmonary V’O2 can be measured by ECG and gas exchange easily. Muscular V’O2 kinetics can be non-invasively estimated by using time-series analysis in combination with a physiological model, comprising the time delay and the distortive effects of the cardio-dynamic phases between muscular and pulmonary level (Hoffmann et. al., in press). Using the mentioned non-invasive approach, we compared the kinetics of upper (Up: arms/torso) and lower body (Lo: legs) exercise for heart rate (HR), pulmonary (V’O2pulm) and in particular for calculated muscular oxygen uptake (V’O2musc).
Methods

11 male volunteers (age: 24 ± 2 years; height: 184 ± 8 cm; weight: 79 ± 7 kg; relV’O2peak(Up): 37.8 ± 5.0 ml•min-1•kg-1; relV’O2peak(Lo): 56.1 ± 7.4 ml•min-1•kg-1) were subjected to pseudo random binary work rate (WR) changes on a leg cycle ergometer (30 W, 80 W) and an arm cranking exercise device (20 W, 50 W). HR was measured beat-to-beat by ECG, V’O2pulm was determined breath-by-breath, and V’O2musc was estimated by the method of Hoffmann et al. (in press) for Up and Lo.Given a linear, time-invariant, first order system the peak of the cross correlation function (CCF) of WR and a second parameter (e. g. HR, V’O2pulm, V’O2musc) indicates the kinetic responses of this parameter (Hpeak, Ppeak, Mpeak). Higher peaks denote faster system responses. Accordingly, for Up and Lo the kinetic responses for HR (Up_Hpeak, Lo_Hpeak), V’O2pulm (Up_Ppeak, Lo_Ppeak) and V’O2musc (Up_Mpeak, Lo_Mpeak) were calculated.Differences between the kinetic responses were statistically analyzed applying a two-way ANOVA (parameter x exercise mode) for repeated measurements.
Results
Significant differences were found between Up_Mpeak (0.341 ± 0.062) and Lo_Mpeak (0.414 ± 0.046; p=.018; n=11). In addition, there were no significant differences between Up_Hpeak (0.465 ± 0.183) and Lo_Hpeak (0.457 ± 0.075; p=.895; n=11), as well as between Up_Ppeak (0.312 ± 0.090) and Lo_Ppeak (0.351 ± 0.072; p=.316; n=11).
Discussion

It can be speculated that there could be differences between upper and lower muscular V’O2 kinetics due to different characteristics of the specific upper and lower body musculature from daily activities. Furthermore, the influence of the individual training status, muscle fiber composition, and enzyme activity, remain to be clarified.The study was funded by the DLR (Deutsches Zentrum für Luft- und Raumfahrt), Germany (FKZ 50WB0726).
References

Hoffmann U, Drescher U, Benson AP, Rossiter HB, Essfeld D (in press).
Original languageEnglish
Title of host publicationBook of abstracts. 18th annual ECSS Congress of the European College of Sport Science
Publication date2013
ISBN (Electronic) 978-84-695-7786-8
Publication statusPublished - 2013
EventAnnual Congress of the European College of Sport Science - Barcelona, Spain
Duration: 26.06.201329.06.2013
Conference number: 18

ID: 255713

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