Blood Lactate

In exhaustive work, aerobic energy sources are supplemented by anaerobic energy sources. The most significant metabolite of anaerobic metabolism is lactate which accumulates in muscle and diffuses into the blood. In this experiment, exercise-induced changes in blood lactate are measured by spectrophotometric analysis of blood samples taken during the experiment.

First, perform the heart rate experiment and briefly consider where and how many blood samples you would collect from the subject for spectrophotometric analysis. Nine blood samples are collected automatically for you during the experiment. A control (pre-exercise sample) is taken automatically at the start of the experiment. Seven more are taken during the experiment and one immediately after the subject becomes exhausted.

Second, measure the absorbance of the prepared lactate standards using the spectrophotometer. Plot a standard curve with lactate concentration (mmol/l) on the x-axis and absorbance (arbitrary units) on the y-axis. This standard curve is necessary to determine the lactate concentration of the blood sample and may be used for subsequent subjects.

Finally, measure the absorbance of each of the blood sample collected during the experiment. Use your standard curve to determine the lactate concentration of each sample.

Plot a graph of blood lactate (y-axis) against workload (x-axis) for the subject.

Measure the maximum HR at each workload.