Ventilatory and Gas Exchange Responses

Ventilatory and Gas Exchange Responses to Exercise The study seeks to investigate the generally accepted relationship between ventilation and the demands of the exercising muscle, in that ventilation is controlled to meet such demands. Increases in such ventilation are linked with arterial CO2 pressure maintenance. Particularly, the rationale of the study is to focus on existing gaps in scientific knowledge regarding for example the exact role of intrabreath CO2 and H+ oscillations.

The hypothesis that CO2 delivery to the lung is the primary stimulus regulating exercise ventilation is also examined, as it has not been scientifically sufficiently proven to be generally accepted. That decreased VCO2 and blood during exercise with reduced muscle glycogen content will not be accompanied by a reduction in exercise VE. O2 delivery to active muscles will be compromised by a fall in VE during exercise.

If there is no fall in exercise VE concomitant with the decrease in VCO2 and blood, other mechanisms will be of importance in exercise ventilation. c. Purpose: To determine the relationship between exercise VE and VCO2 in the blood as a result of glycogen reduction. d. Methods: Nine untrained female volunteer subjects were used for the study, with an average age of 25.3 years, and average height of 166.5 cm, and an average body mass of 61.3kg.

Three cycle ergometer tests were performed to volitional exhaustion, two of which occurred in the normal glycogen state and the third in the reduced muscle glycogen state. Each test occurred on 8 o'clock in the morning on three separate days, after an overnight fast. Subjects did not change their diet during the test period. All were on the oral contraceptive pill, with regular menstrual cycles, with tests performed during the first six days of the follicular phase. Statistical analysis results are presented as +/- S.D.

Intra-class correlation coefficients were determined for VO2peak and GET values. ANOVA was used for the examination of differences at 20, 40, 60, 80, and 100% of VO2peak. Pair-wise comparisons were made with Bonferroni post hoc adjustments. The relationship between VE and VCO2 for each subject was examined by linear regression analysis. e. Results: There was a reduction in average body mass to 60.4 kg when the glycogen-reduction procedure was performed. The body mass difference between NG and RG conditions was estimated to be statistically significant. f.

Interpretation: It was found that the reduction in blood, VCO2 and RER suggests in increase in fat oxidation during exercise in the RG state. This means a reduction in exercise efficiency at a given intensity. The fall in blood and VCO2 did not work concomitantly with a reduction in exercise VE. Critique a. Rationale: The rationale is clearly stated in terms of existing knowledge in combination with areas of investigation that still need attention. The rationale is further justified by addressing the specific gaps identified in the hypothesis. b.

Hypothesis and purpose: The hypothesis and purpose correlate well with the rationale and identified gaps in existing knowledge. Relevant alternatives to the hypothesis are identified in the introduction when addressing the issue of CO2 delivery. The purpose and hypothesis of the study are therefore clearly stated. c. Methods and Design: The method of investigation appears to be valid in terms of the specific method focusing on exercises and measurement techniques. However, in terms of subject choice, there appear to be some limitations.

Study results may have been of higher quality had a greater diversity of groups been used for the study. Males and females of various age, weight and activity levels could have been included, for example, with each group investigated separately and the compared. The result would have been a wider diversity of results, and a better interpretation of the exact relationship between VCO2 and VE.

While significant results were obtained, I do believe that the wide diversity of humanity will have better been served by a more representative set of research subjects. Important cautionary measures may have been identified, for example, for different weight and age groups when engaging in exercise of various intensity. For the specific purpose of the study, however, I do believe that the design and statistical analysis are sufficiently appropriate. This study could then be used as a basis for future investigations.