Interpreting Lactate Curves (Coaches Presentation)

The following posts are from a presentation that we prepared for the USAT coaching clinic. You will find an accompanying podcast at http://endurancecorner.libsyn.com

Part I: Critical Markers
Alan Couzens, MS (Sports Science), CSCS, PES

* Objectives
- Show coaches how to use lactate testing to better individualize training prescriptions

* What is Lactate
- By-product of glycolysis (carbohydrate metabolism)

* What does an elevation in blood lactate signify?
- Greater dependence on glycolysis for energy production
- Reduced ability to clear the lactate being produced

* Critical Markers on the lactate curve
- 3 fiber types
- Slow Oxidative (SO)
- Fast Oxidative Glycolytic (FOG)
- Fast Glycolytic

- 3 Critical Markers on the Lactate Curve
- AeT
- LT1/VT1
- LT2/VT2/FT


* AeT (Aerobic Threshold)
- A shift in fiber recruitment from SO to FOG (McLellan and Skinner, 1980)
- First deepening of breath (breathing through mouth)
- First uptick on the lactate curve
- HR ~ 30-50BBM relative to fitness (Hellemans, 1999; Sweetenham, 2001)
- Generally occurs at 35-60% VO2max/50-70% vVO2max (Martin, 1997)- Higher values possible in elite Ironman athletes

* LT1/VT1 (“Lactate Threshold”)
- A fiber recruitment shift from FOG to FG (Hagberg & Coyle, 1984)
- Notable increase in expiratory stimulus (i.e. breathing becomes loud)
- Heart Rate ~20-40BBM depending on fitness (Hellemans, 1998)
- Heart Rate ~8-15BBM below VT2 (Dave Scott)
- 79-89% vVO2max for elite athletes (Padilla et al, 1999)
- ~ 1mmol above mean baseline values (Hagberg & Coyle, 1984,
USOC protocol)

* LT2/VT2 (“Functional Threshold”/ “OBLA”)

- The point at which the SO fibers, liver and heart can no longer metabolize/oxidize the lactic acid being produced by the FG fibers.
- Notable increase in rate of expiration as ventilation can no longer keep up with the need for CO2 removal (“Panting”)
- HR ~10-30BBM relative to fitness (Hellemans, 1998)
- Elite values typically 80-90% VO2max/85-95% vVO2max (Martin, 1997)
- This is a “functional threshold” because the athlete’s ability to accumulate training time above this threshold is severely diminished when compared to tolerance to training just below this threshold.
- Methods of assessing from Lactate Curve
· Clear deflection point
· Modified DMax (AIS, 1987)

Stay tuned for an accompanying article on using these critical markers to set training zones.