1

AIS Chapter 6Blood lactate thresholds

2

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

4

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

5

Lactate response after training adaptation

6

Lactate response after training adaptation

7

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

8

LT1 and LT2

9

Fixed lactate concentration2.0, 2.2, 2.5, 3.0, 4.0 mM

10

Individualized lactate threshold

Lactate E for ADAPT: http://www.nuigalway.ie/maths/jn/LACTATE/html/lactate-e.html

11

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)

12

Lactate concentrations in difference durations of stages

13

LT2 occurs at different lactate concentrations for difference exercise modes

14

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

15

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

16

Endurance training zones

17

Training adaptations in lactate concentration

18

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)