Lactate inflection point (LIP) is the exercise intensity at which the blood concentration of lactate and/or lactic acid begins to increase rapidly.[1] It is often expressed as 85% of maximum heart rate or 75% of maximum oxygen intake.[2] When exercising at or below the lactate threshold, any lactate produced by the muscles is removed by the body without it building up.[3]
The onset of blood lactate accumulation (OBLA) is often confused with the lactate threshold. With an exercise intensity higher than the threshold the lactate production exceeds the rate at which it can be broken down. The blood lactate concentration will show an increase equal to 4.0 mM; it then accumulates in the muscle and then moves to the bloodstream.[2]
Regular endurance exercise leads to adaptations in skeletal muscle which raises the threshold at which lactate levels will rise. This is mediated via activation of the protein receptor PGC-1α, which alters the isoenzyme composition of the lactate dehydrogenase (LDH) complex and decreases the activity of lactate dehydrogenase A (LDHA), while increasing the activity of lactate dehydrogenase B (LDHB).[4]
- ^ Goodwin, Matthew L.; Harris, James E.; Hernández, Andrés; Gladden, L. Bruce (Jul 2007). "BlLactate Measurements and Analysis during Exercise: A Guide for Clinicians". J Diabetes Sci Technol. 1 (4): 558–569. doi:10.1177/193229680700100414. PMC 2769631. PMID 19885119.
- ^ a b McPartland, Darren; Pree, Adrian; Malpeli, Robert; Telford, Amanda (2010). Nelson Physical Education Studies For WA. Australia: Nelson. ISBN 9780170182027.
- ^ Cite error: The named reference
:3was invoked but never defined (see the help page). - ^ Serge Summermatter; Gesa Santos; Joaquín Pérez-Schindler; Christoph Handschin (21 May 2013). "Skeletal muscle PGC-1α controls whole-body lactate homeostasis through estrogen-related receptor α-dependent activation of LDH B and repression of LDH A". Proceedings of the National Academy of Sciences. 110 (21): 8738–43. Bibcode:2013PNAS..110.8738S. doi:10.1073/pnas.1212976110. PMC 3666691. PMID 23650363.