A Review by Alyssa Bialowas

Tools for aerobic fitness evaluation in endurance training are used in sport and clinical fields to test blood lactate levels for training and competition. Anaerobic threshold (LTAN) is defined as the point during exercise at which lactic acid starts to accumulate in the muscles, the point in intense exercise that anaerobic processes become more dominant. Endurance performance prediction and prescribing optimal training intensities are two important applications of studying anaerobic threshold.

There is controversy in the sport and clinical fields around the need to develop additional tools for aerobic fitness evaluation, and their validity to determine aerobic fitness. The purpose of this study was to analyze the sensitivity of glucose minimum intensity (GMI) and LMI to endurance training.

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The Study

A group of 8 trained cyclists participated in this study. They completed two sets of tests, one after the off-season period in March and the other after 12 weeks of training in June. The first test consisted of a maximal incremental test to evaluate the maximal oxygen uptake (VO2max), and the second assessed LMI and GMI intensity.

The GMI and LMI test started off with a 30 second Windgate test (an all-out, very difficult anaerobic exercise test performed on a stationary bike), followed by 8 minutes of rest, and then cycled until voluntary exhaustion. In the end of each stage, blood samples were taken, and heart rate was monitored during the test.

The training program consisted of 12 weeks at three different testing intensities, and blood lactate was determined after testing in each zone.

The Results

In the tests after training, blood lactate levels after maximal exercise was significantly greater than in pre-testing. No significant differences were found in blood glucose levels between pre and post. In all of the cyclists, VO 2 max, LMI, and GMI increased significantly after 12 weeks of high intensity endurance training.

Takeaway

Both GMI and LMI are important indexes of aerobic fitness, and can be used as an important index to training prescription in well-trained cyclists and athletes. High intensity interval training proved very effective in improving maximal oxygen uptake, and should be used as a training tool for improving aerobic fitness.

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Reference

Campos, E., de Andrade, V., de Araujo, G., Junior, P., Kalva-Filho, C., Papoti, M., &

Zagatto, A. “Effect of Endurance Training on The Lactate and Glucose Minimum Intensities.” Journal of Sport Science and Medicine, 17, 117-123.