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The lactate threshold (LT) or lactate inflection point (LIP), is the exercise intensity at which the blood concentration of lactate and/or lactic acid begins to exponentially increase. The reason for the increased lactate concentration in the blood at high exercise intensities muscle cells release lactate into the blood to be converted back into glucose by the liver (see the Cori Cycle): the high rates of ATP hydrolysis in the muscle release hydrogen ions, as they are co-transported out of the muscle into the blood via the MCT— monocarboxylate transporter, and also bicarbonate stores in the blood begin to be used up. This happens when lactate is produced faster than it can be removed (metabolized) in the muscle. When exercising at or below the LT, any lactate produced by the muscles is removed by the body without it building up. With a higher exercise intensity the lactate level in the blood reaches the anaerobic threshold (AT), or the onset of blood lactate accumulation (OBLA). The lactate threshold is a useful measure for deciding exercise intensity for training and racing in endurance sports (e.g. long distance running, cycling, rowing, swimming and cross country skiing), but varies between individuals and can be increased with training. Interval training takes advantage of the body being able to temporarily exceed the lactate threshold, and then recover (reduce blood-lactate) while operating below the threshold and while still doing physical activity. Fartlek and interval training are similar, the main difference being the structure of the exercise. Interval training can take the form of many different types of exercise and should closely replicate the movements found in the sport. == Measuring lactate threshold == Accurately measuring the lactate blood concentration involves taking blood samples (normally a pinprick to the finger, earlobe or thumb) during a ramp test where the exercise intensity is progressively increased. Measuring the threshold can also be performed non-invasively using gas-exchange (Respiratory quotient) methods, which requires a metabolic cart to measure air inspired and expired. Another way to measure lactate levels non-invasively is using Near-infrared spectroscopy. There are wearable NIRS sensors for professionals, so they can monitor their lactate levels real-time. Although the lactate threshold is defined as the point when lactic acid starts to accumulate, some testers approximate this by using the point at which lactate reaches a concentration of 4 mM (at rest it is around 1 mM). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Lactate threshold」の詳細全文を読む スポンサード リンク
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