Energy systems: Lactate sampling.

The idea

Lactate sampling measures blood lactate concentration to indicate how much the anaerobic glycolytic (lactate) energy system has contributed during exercise. A small blood sample is taken, typically from a fingertip or earlobe, at rest and at set intervals during or after exercise, then analysed with a portable lactate analyser. Rising lactate above resting values shows increasing reliance on anaerobic glycolysis; the point where lactate begins to accumulate faster than it can be cleared is often used to estimate the lactate threshold and to set training intensities. Sampling timing matters: readings taken immediately after a bout differ from those taken during recovery, so results must be interpreted against the protocol used.

What earns the marks

• Lactate sampling measures blood lactate concentration, usually from a fingertip or earlobe blood sample.
• A portable lactate analyser is used to read the concentration, often in mmol·dm⁻³.
• Lactate rises when the anaerobic glycolytic (lactate) system contributes more to ATP resynthesis than lactate can be cleared.
• The lactate threshold is the exercise intensity at which blood lactate begins to accumulate above resting levels.
• Sampling timing (during exercise versus recovery) affects the reading, so results are interpreted against the protocol used.
• Lactate sampling can be used to monitor training intensity and to estimate the lactate threshold.

Common mistakes and how to put them right

• Thinking lactate is the direct cause of the burning sensation and of delayed onset muscle soreness.

  Put it right: Lactate is a metabolic by-product that is cleared and reused, and the burning sensation relates to other factors such as hydrogen ion accumulation.

• Believing lactate only appears when the body has run out of oxygen.

  Put it right: Lactate is produced continuously, and it accumulates when production exceeds clearance, which can occur even when oxygen is available.

• Assuming a single lactate reading gives a complete picture of fitness.

  Put it right: Lactate must be interpreted against the exercise intensity and the sampling time, and often several samples across intensities are needed.

• Confusing lactate with lactic acid as if they were identical in the blood.

  Put it right: At blood pH, lactate exists largely as the lactate ion, and lactate sampling measures lactate concentration.

Exam tips

• Link each lactate value to the exercise intensity and timing at which it was taken, rather than quoting a number in isolation.
• Use the term lactate threshold precisely: the intensity at which lactate accumulation begins to exceed clearance.
• When comparing two performers, compare their lactate responses at the same relative intensity to make the comparison valid.