Post on 01-Jan-2016
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AIS Chapter 6Blood 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
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
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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 concentration2.0, 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– 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 (p113-
114)• Chapter 26 Runners and walkers (p401-408)