AIS Chapter 6
Blood lactate thresholds
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Production of Lactic Acid (lactate)
• Normally, O2 is available in the mitochondria
to accept H+ (and electrons) from NADH
produced in glycolysis
– In anaerobic pathways, O2 is not available
• H+ and electrons from NADH are accepted by
pyruvic acid (pyruvate) to form lactic acid
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Conversion of Pyruvic Acid to
Lactic Acid
• Recycling of NAD (NADH  NAD)
• So that glycolysis can continue
• LDH: lactate dehydrogenase 乳酸去氫脢
Blood lactate testing rationale
• Indicators of training adaptation
– Adapts to a greater degree than VO2max
– Especially true in highly trained athletes
• Correlate with endurance performance
– Better indicator than VO2max
• Optimal training stimuli
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Lactate response after training
adaptation
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Lactate response after training
adaptation
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Definitions of lactate threshold
• Various terminology
– Anaerobic threshold, aerobic-anaerobic threshold, onset
of blood lactate accumulation (OBLA)
• Lactate threshold 1 (LT1)
– First exercise intensity at which there is a sustained
increase in lactate above resting level
– Usually < 2.0 mM
• Lactate threshold 1 (LT2)
– First exercise intensity at which there is a very rapid
increase in lactate
– Shift from oxidative to partly anaerobic energy
– 2.5-5.5 mM
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LT1 and LT2
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Fixed lactate concentration
2.0, 2.2, 2.5, 3.0, 4.0 mM
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Individualized lactate threshold
Lactate E for ADAPT: http://www.nuigalway.ie/maths/jn/LACTATE/html/lactate-e.html
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Test protocols
• Incremental duration: 5-8 min
– < 5 min may overestimate LT2
– Especially the purpose is to prescribe exercise
intensity for endurance training
• Rest interval duration: 0-60 s
– For blood collection and/or modify equipment
• Number of increments: 5-7
– Relatively small increments in intensity: 1-2 km/hr
per stage (~1 km/hr perferred)
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Lactate concentrations in difference
durations of stages
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LT2 occurs at different lactate concentrations for
difference exercise modes
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Lactate concentration in muscle and
blood
• Strong correlation between muscle and blood
lactate concentration
• Blood lactate NOT wholly reflective of muscle
lactate
• High muscle lactate requires significant time
lag before lactate equilibrates with blood
– Require longer (> 5 min) stage duration
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Practical applications
• Use individually measured LT1 and LT2
• Prescribe endurance training intensities
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T1: light aerobic
T2: moderate aerobic
T3: heavy aerobic
T4: anaerobic threshold
T5: maximal aerobic
• Evaluate training adaptations
– Graphical overlays for subjective assessment
– ↑intensity at LT1: ↑ base aerobic condition
– ↑intensity at LT2: ↑high-level aerobic endurance
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Endurance training zones
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Training adaptations in lactate
concentration
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Homework
• Design protocols for running MAOD (p67-68)
• Design protocols for running lactate threshold
(p84-89)
• Design protocols for running VO2max (p113114)
• Chapter 26 Runners and walkers (p401-408)
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