Lactate Threshold
Introduction pending.
Contents
1 What is Lactate?
Main article: Lactate
At one time Lactate was viewed as a harmful waste product due anaerobic exercise, but research since the early 2000s has shown that Lactate is an intermediate fuel in the metabolism of carbohydrates. Muscles will burn Lactate in preference to Glucose, and will convert Lactate back to Glucose at rest. The level of Lactate in the blood is primarily dependent on exercise intensity. Note that Lactate forms Lactic Acid in the blood, and the terms are used interchangeably. Lactate is used as a fuel source by working muscles, and injecting extra lactate into the blood results in increased lactate metabolism and carbohydrate sparing[1] without impairing performance[2].
2 What is the Lactate Threshold?
The Lactate Threshold (LT) is the point at which the lactate level in the blood will rise even if the work intensity is kept constant. This is sometimes referred to as the Anaerobic Threshold (AT), or the Onset of Blood Lactate Accumulation (OBLA), though the most accurate term is Maximal Lactate Steady State (MLSS). Even within the scientific community terminology is confusing[3]. It is sometimes believed that the MLSS represents the maximum clearance of Lactate, but this may not be the case[2]. Note that Lactate is normally measured in the blood stream, so the Lactate level reflects the net of the muscles releasing and absorbing Lactate. Lactate Threshold is important as it is an excellent good predictor of race performance[4][5][6][7]. Lactate Threshold can be thought of as the percentage of VO2max that can be maintained for a protracted time[8], though it's not clear what the limiting factor is for exercise above the Lactate Threshold[9].
3 Lactate Curve
It is common to plot exercise intensity against lactate level to produce a blood lactate curve similar to the one below, showing an exponential rise in lactate level with intensity. It's generally accepted that a shift of the curve to the right indicates an improved athletic performance[10][11], and training can improve performance because of this shift without a change in aerobic capacity (V̇O2max)[12]. There is some limited evidence from radio-isotope studies in animals that a benefit of endurance training may be in Lactate clearance[13]. Note that above the Lactate Threshold the Lactate level is not at a steady state, but rises even though the intensity remains constant, so the typical curve that is shown is rather misleading.
4 Lactate Threshold Training
Main article: Tempo Runs
There is good evidence that endurance training changes Lactate Threshold. However, the idea that training at threshold intensity (Tempo Runs) is particularly effective has no evidence[14]"/>[15], and polarized training is a better approach[16][17]. For trained athletes, Tempo runs are ineffective[18] and may actually be counterproductive[19][15]. See Tempo Runs for more details. Detraining shifts the curve to the left[20]. Lactate levels can be higher at a given intensity after just a few days without training[21], suggesting rapid detraining effects.
5 Determining Lactate Threshold
There are various ways of determining the Lactate Threshold, each with their own problems.
- MLSS. The gold standard test (and the only one that appears to be valid) is to measure Maximal Lactate Steady State (MLSS). The test requires 3 to 5 constant intensity trials of at least 30 minutes' duration, each performed on separate days. Each test is at a different exercise intensity, and the highest intensity that does not have a rise in blood lactate in the last 20 minutes is the MLSS. While this is the best way of determining Lactate threshold, it's obviously time consuming and interferes with the athlete's regular training. Because of the effort of MLSS testing, various shortcuts have been tried.
- Fixed Blood Lactate Accumulation. A simple approach is to assume that Lactate Threshold always occurs at the same Lactate level. Sadly, this assumption is wrong, as Lactate Threshold can occur at vastly different levels.
- Lactate Patterns. There are various approaches that look at the pattern of change in Lactate in an attempt to create a simple test. So far, I've seen little evidence to support any of these approaches.
- Heart Rate Deflection. An indirect way of finding Lactate Threshold is to look for the Heart Rate Deflection, sometimes called the "Conconi test". This test only requires a heart rate monitor to perform rather than blood draws, so it is much easier than the above approaches. However, the validity of the Conconi test has many issues and seems of dubious value[22]. See Heart Rate Deflection for details.
- Respiratory gasses. Another method for estimating Lactate Threshold is to measure the respiratory gasses[3][23], but given this is impractical for most athletes, it's not covered here.
5.1 Lactate Threshold & Maximal Lactate Steady State
The best approach to determine Lactate Threshold is to measure the Maximal Lactate Steady State (MLSS)[24]. The test is actually several constant load trials of at least 30 minutes' duration on different days at various exercise intensities (in the range of 50–90% V̇O2max. The highest workload that results in an increase of less than 1 mmol/L of lactate between the 10 and 30 minute mark defines the MLSS[25][26][27]. Lactate is typically measured using a blood sample, either using a pinprick or a catheter. Note that MLSS for a given individual will vary by sport[28], probably based on the mass of muscle engaged[29][30]. The difficulty of performing this test makes it impractical in most situations.
5.2 Lactate Threshold & Incremental Power Test
A common approach to determine the Lactate Threshold is the Incremental Power Test. The subject exercises in stages of increasing intensity, with lactate measured at the end of each stage, with stages typically lasting 3 to 10 minutes. However, blood lactate takes 20-30 minutes to stabilize for a given intensity[4]. This means that the incremental power test tends to be of limited value[31], with 3 minute stages giving low reproducibility[32], the stage length changing the lactate values[24], and even longer stages lengths of 8 minutes having low reproducibility[33]. The lactate level can drop between the 4th and 12th minute of exercise at a constant intensity[34]. Some have suggested using the lactate value measured as an indication of the prior stage's intensity, as it takes more than 3 minutes for lactate to stabilize[35], but this rather arbitrary approach can be used as a guideline (at best)[6]. For running, it is common to pause the exercise for 30 seconds to take a blood sample. These breaks only make a non-significant difference to the testing, though the slight difference tends to be greater at higher intensities[36].
5.3 Lactate Threshold & Fixed Blood Lactate Accumulation
Because MLSS is time consuming and expensive, a shortcut is often used to estimate MLSS by assuming that it occurs at a fixed Lactate Level (Fixed Blood Lactate Accumulation, or FBLA)[26], unusually 4.0 mmol/l[37] though sometimes 3.5 mmol/l[38][39]. However, while the MLSS may average around 4.0 mmol/l[39], there are significant differences for individuals[40], with variations between 3.0 and 5.5 in small sample sizes[37] and has been shown to have a range as wide as 2.0 to 10.0 mmol/l[24][41]. This approach also typically uses a blood test, but in some sports (like running), the athlete has to pause to have a pinprick blood sample taken, further confusing the test[37]. The term "Individual Anaerobic Threshold" (IAT) has been used to emphasize that the Lactate Threshold is specific to each individual rather than using a FBLA, though this can refer to a specific protocol for estimating MLSS[41]. The Fixed Blood Lactate Accumulation is sometimes called "Onset of Blood Lactate Accumulation" (OBLA)[40], a particularly misleading term in this context.
5.4 Lactate Threshold Estimation From Lactate Patterns
There have been several approaches to determining MLSS without the difficulty of the full protocol[42][43][5][44][45][25], but their validity is limited[46][26][47]. These approaches generally look for some pattern in the change of Lactate level. For example, one approach called the "Lactate Minimum Speed Test" (LMST) uses an initial sprint to elevate blood lactate followed by an incremental power test[48][49][50]. However, the effectiveness of the LMST is profoundly impacted by the starting speed of the incremental portion of the test[51]and so the results may be coincidence[52]. This is not entirely surprising given the initial sprint phase disrupts the metabolism[52]. Part of the problem with these approaches may be that MLSS may not represent the point of maximum lactate clearance[30], as injecting additional lactate into the blood of athletes exercising above MLSS did not significantly increase lactate levels[2]. Some of the tests could be "p-hacking", where the study looks at a sufficiently large number of variables that some correlation occurs randomly[53].
6 Factors that may influence Lactate Threshold
There are a few factors that may change the Lactate Threshold (other than training)
- Because lactate is produced from the metabolism of carbohydrate, a reduction in carbohydrate intake (or Glycogen depletion) will shift the lactate curve to the right[54][55][56][57].
- It's not clear if Delayed Onset Muscle Soreness changes the lactate curve as there are reports that it does[58] and reports that it does not[59].
- Lactate Threshold will vary by sport, probably based on the mass of muscle engaged[29], or because the inactive muscles consume more lactate as the concentration rises[35]. MLSS may also vary with environmental conditions, with a lower lactate levels at MLSS in hotter conditions[60].
7 Aerobic Threshold
There is a related concept called "Aerobic Threshold" that is generally used to mean the exercise intensity at which Lactate levels rise above resting baselines[24]. This threshold is believed to be the upper limit of nearly exclusive use of aerobic metabolism that can be sustained for many hours. Intensities just above the aerobic threshold can be maintained for prolonged periods (~4 hours)[61]. This aerobic threshold can be hard to determine in untrained subjects as it occurs at very low intensities[62]. Unfortunately, the term "Lactate Threshold" is sometimes used to mean this point where lactate rises above resting levels[55].
8 References
- ↑ Benjamin F. Miller, Jill A. Fattor, Kevin A. Jacobs, Michael A. Horning, Franco Navazio, Michael I. Lindinger, George A. Brooks, Lactate and glucose interactions during rest and exercise in men: effect of exogenous lactate infusion, The Journal of Physiology, volume 544, issue 3, 2002, pages 963–975, ISSN 00223751, doi 10.1113/jphysiol.2002.027128
- ↑ 2.0 2.1 2.2 Darren Ellis, Catherine Simmons, Benjamin F. Miller, Sodium lactate infusion during a cycling time-trial does not increase lactate concentration or decrease performance, European Journal of Sport Science, volume 9, issue 6, 2009, pages 367–374, ISSN 1746-1391, doi 10.1080/17461390903009158
- ↑ 3.0 3.1 RK. Binder, M. Wonisch, U. Corra, A. Cohen-Solal, L. Vanhees, H. Saner, JP. Schmid, Methodological approach to the first and second lactate threshold in incremental cardiopulmonary exercise testing., Eur J Cardiovasc Prev Rehabil, volume 15, issue 6, pages 726-34, Dec 2008, doi 10.1097/HJR.0b013e328304fed4, PMID 19050438
- ↑ 4.0 4.1 LV. Billat, Use of blood lactate measurements for prediction of exercise performance and for control of training. Recommendations for long-distance running., Sports Med, volume 22, issue 3, pages 157-75, Sep 1996, PMID 8883213
- ↑ 5.0 5.1 AS. Palmer, JA. Potteiger, KL. Nau, RJ. Tong, A 1-day maximal lactate steady-state assessment protocol for trained runners., Med Sci Sports Exerc, volume 31, issue 9, pages 1336-41, Sep 1999, PMID 10487377 Cite error: Invalid
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tag; name "Palmer-1999" defined multiple times with different content - ↑ 6.0 6.1 C. Baldari, L. Guidetti, A simple method for individual anaerobic threshold as predictor of max lactate steady state., Med Sci Sports Exerc, volume 32, issue 10, pages 1798-802, Oct 2000, PMID 11039656
- ↑ AM. Jones, H. Carter, The effect of endurance training on parameters of aerobic fitness., Sports Med, volume 29, issue 6, pages 373-86, Jun 2000, PMID 10870864
- ↑ DL. Costill, H. Thomason, E. Roberts, Fractional utilization of the aerobic capacity during distance running., Med Sci Sports, volume 5, issue 4, pages 248-52, 1973, PMID 4774203
- ↑ B. Baron, TD. Noakes, J. Dekerle, F. Moullan, S. Robin, R. Matran, P. Pelayo, Why does exercise terminate at the maximal lactate steady state intensity?, Br J Sports Med, volume 42, issue 10, pages 828-33, Oct 2008, doi 10.1136/bjsm.2007.040444, PMID 18070803
- ↑ L. Bosquet, L. Léger, P. Legros, Methods to determine aerobic endurance., Sports Med, volume 32, issue 11, pages 675-700, 2002, PMID 12196030
- ↑ T. Yoshida, M. Udo, M. Chida, M. Ichioka, K. Makiguchi, T. Yamaguchi, Specificity of physiological adaptation to endurance training in distance runners and competitive walkers., Eur J Appl Physiol Occup Physiol, volume 61, issue 3-4, pages 197-201, 1990, PMID 2282901
- ↑ EO. Acevedo, AH. Goldfarb, Increased training intensity effects on plasma lactate, ventilatory threshold, and endurance., Med Sci Sports Exerc, volume 21, issue 5, pages 563-8, Oct 1989, PMID 2607946
- ↑ CM. Donovan, GA. Brooks, Endurance training affects lactate clearance, not lactate production., Am J Physiol, volume 244, issue 1, pages E83-92, Jan 1983, PMID 6401405
- ↑ R. Beneke, RM. Leithäuser, O. Ochentel, Blood lactate diagnostics in exercise testing and training., Int J Sports Physiol Perform, volume 6, issue 1, pages 8-24, Mar 2011, PMID 21487146
- ↑ 15.0 15.1 A. Guellich, S. Seiler, Lactate profile changes in relation to training characteristics in junior elite cyclists., Int J Sports Physiol Perform, volume 5, issue 3, pages 316-27, Sep 2010, PMID 20861522
- ↑ Thomas Stöggl, Billy Sperlich, Polarized training has greater impact on key endurance variables than threshold, high intensity, or high volume training, Frontiers in Physiology, volume 5, 2014, ISSN 1664-042X, doi 10.3389/fphys.2014.00033
- ↑ I. Muñoz, S. Seiler, J. Bautista, J. España, E. Larumbe, J. Esteve-Lanao, Does polarized training improve performance in recreational runners?, Int J Sports Physiol Perform, volume 9, issue 2, pages 265-72, Mar 2014, doi 10.1123/ijspp.2012-0350, PMID 23752040
- ↑ BR. Londeree, Effect of training on lactate/ventilatory thresholds: a meta-analysis., Med Sci Sports Exerc, volume 29, issue 6, pages 837-43, Jun 1997, PMID 9219214
- ↑ F. Evertsen, JI. Medbø, A. Bonen, Effect of training intensity on muscle lactate transporters and lactate threshold of cross-country skiers., Acta Physiol Scand, volume 173, issue 2, pages 195-205, Oct 2001, doi 10.1046/j.1365-201X.2001.00871.x, PMID 11683677
- ↑ EF. Coyle, WH. Martin, SA. Bloomfield, OH. Lowry, JO. Holloszy, Effects of detraining on responses to submaximal exercise., J Appl Physiol (1985), volume 59, issue 3, pages 853-9, Sep 1985, PMID 3902770
- ↑ I. Mujika, S. Padilla, Cardiorespiratory and metabolic characteristics of detraining in humans., Med Sci Sports Exerc, volume 33, issue 3, pages 413-21, Mar 2001, PMID 11252068
- ↑ I Cook, Was the Conconi test validated by sporting success, expert opinion or good science?, South African Journal for Research in Sport, Physical Education and Recreation, volume 33, issue 1, 2011, ISSN 0379-9069, doi 10.4314/sajrs.v33i1.65483
- ↑ D. Laplaud, M. Guinot, A. Favre-Juvin, P. Flore, Maximal lactate steady state determination with a single incremental test exercise., Eur J Appl Physiol, volume 96, issue 4, pages 446-52, Mar 2006, doi 10.1007/s00421-005-0086-4, PMID 16341873
- ↑ 24.0 24.1 24.2 24.3 O. Faude, W. Kindermann, T. Meyer, Lactate threshold concepts: how valid are they?, Sports Med, volume 39, issue 6, pages 469-90, 2009, PMID 19453206
- ↑ 25.0 25.1 A. Urhausen, B. Coen, B. Weiler, W. Kindermann, Individual anaerobic threshold and maximum lactate steady state., Int J Sports Med, volume 14, issue 3, pages 134-9, Apr 1993, doi 10.1055/s-2007-1021157, PMID 8509241
- ↑ 26.0 26.1 26.2 Kristopher Mendes De Souza, Talita Grossl, Rubens José Babel Junior, Ricardo Dantas De Lucas, Vitor Pereira Costa, Luiz Guilherme Antonacci Guglielmo, Máximo estado estável de lactato estimado por diferentes métodos de determinação, Revista Brasileira de Cineantropometria e Desempenho Humano, volume 14, issue 3, 2012, ISSN 1980-0037, doi 10.5007/1980-0037.2012v14n3p264
- ↑ R. Beneke, Methodological aspects of maximal lactate steady state-implications for performance testing., Eur J Appl Physiol, volume 89, issue 1, pages 95-9, Mar 2003, doi 10.1007/s00421-002-0783-1, PMID 12627312
- ↑ TR. Figueira, F. Caputo, JG. Pelarigo, BS. Denadai, Influence of exercise mode and maximal lactate-steady-state concentration on the validity of OBLA to predict maximal lactate-steady-state in active individuals., J Sci Med Sport, volume 11, issue 3, pages 280-6, Jun 2008, doi 10.1016/j.jsams.2007.02.016, PMID 17553745
- ↑ 29.0 29.1 R. Beneke, SP. von Duvillard, Determination of maximal lactate steady state response in selected sports events., Med Sci Sports Exerc, volume 28, issue 2, pages 241-6, Feb 1996, PMID 8775160
- ↑ 30.0 30.1 R. Beneke, Maximal lactate steady state concentration (MLSS): experimental and modelling approaches., Eur J Appl Physiol, volume 88, issue 4-5, pages 361-9, Jan 2003, doi 10.1007/s00421-002-0713-2, PMID 12527964
- ↑ P. Foxdal, A. Sjödin, B. Sjödin, Comparison of blood lactate concentrations obtained during incremental and constant intensity exercise., Int J Sports Med, volume 17, issue 5, pages 360-5, Jul 1996, doi 10.1055/s-2007-972861, PMID 8858408
- ↑ RH. Morton, SR. Stannard, B. Kay, Low reproducibility of many lactate markers during incremental cycle exercise., Br J Sports Med, volume 46, issue 1, pages 64-9, Jan 2012, doi 10.1136/bjsm.2010.076380, PMID 21343140
- ↑ JP. Gavin, ME. Willems, SD. Myers, Reproducibility of lactate markers during 4 and 8 min stage incremental running: a pilot study., J Sci Med Sport, volume 17, issue 6, pages 635-9, Nov 2014, doi 10.1016/j.jsams.2013.08.006, PMID 24028777
- ↑ M. Rieu, J. Miladi, A. Ferry, A. Duvallet, Blood lactate during submaximal exercises, European Journal of Applied Physiology and Occupational Physiology, volume 59, issue 1-2, 1989, pages 73–79, ISSN 0301-5548, doi 10.1007/BF02396583
- ↑ 35.0 35.1 CJ. Orok, RL. Hughson, HJ. Green, JA. Thomson, Blood lactate responses in incremental exercise as predictors of constant load performance., Eur J Appl Physiol Occup Physiol, volume 59, issue 4, pages 262-7, 1989, PMID 2583172
- ↑ L. Gullstrand, B. Sjüdin, J. Svedenhag, Blood sampling during continuous running and 30-second intervals on a treadmill, Scandinavian Journal of Medicine & Science in Sports, volume 4, issue 4, 2007, pages 239–242, ISSN 09057188, doi 10.1111/j.1600-0838.1994.tb00434.x
- ↑ 37.0 37.1 37.2 37.3 H. Heck, A. Mader, G. Hess, S. Mücke, R. Müller, W. Hollmann, Justification of the 4-mmol/l lactate threshold., Int J Sports Med, volume 6, issue 3, pages 117-30, Jun 1985, doi 10.1055/s-2008-1025824, PMID 4030186
- ↑ B.S. Denadai, T.R. Figueira, O.R.P. Favaro, M. Gonçalves, Effect of the aerobic capacity on the validity of the anaerobic threshold for determination of the maximal lactate steady state in cycling, Brazilian Journal of Medical and Biological Research, volume 37, issue 10, 2004, pages 1551–1556, ISSN 1678-4510, doi 10.1590/S0100-879X2004001000015
- ↑ 39.0 39.1 BS. Denadai, EB. Gomide, CC. Greco, The relationship between onset of blood lactate accumulation, critical velocity, and maximal lactate steady state in soccer players., J Strength Cond Res, volume 19, issue 2, pages 364-8, May 2005, doi [364:TRBOOB2.0.CO;2 10.1519/1533-4287(2005)19[364:TRBOOB]2.0.CO;2], PMID 15903376
- ↑ 40.0 40.1 Mamen, Asgeir. "Estimating the Maximal Lactate Steady State Power from an Incremental Test Using Lactate Pro (R) LP1710." International Journal of Applied sports sciences (IJASS) 21.1 (2009): 74-85.
- ↑ 41.0 41.1 H. Stegmann, W. Kindermann, A. Schnabel, Lactate kinetics and individual anaerobic threshold., Int J Sports Med, volume 2, issue 3, pages 160-5, Aug 1981, doi 10.1055/s-2008-1034604, PMID 7333753
- ↑ V. Billat, F. Dalmay, MT. Antonini, AP. Chassain, A method for determining the maximal steady state of blood lactate concentration from two levels of submaximal exercise., Eur J Appl Physiol Occup Physiol, volume 69, issue 3, pages 196-202, 1994, PMID 8001529
- ↑ CR. Harnish, TC. Swensen, RR. Pate, Methods for estimating the maximal lactate steady state in trained cyclists., Med Sci Sports Exerc, volume 33, issue 6, pages 1052-5, Jun 2001, PMID 11404673
- ↑ U. Tegtbur, MW. Busse, KM. Braumann, Estimation of an individual equilibrium between lactate production and catabolism during exercise., Med Sci Sports Exerc, volume 25, issue 5, pages 620-7, May 1993, PMID 8492691
- ↑ HH. Dickhuth, L. Yin, A. Niess, K. Röcker, F. Mayer, HC. Heitkamp, T. Horstmann, Ventilatory, lactate-derived and catecholamine thresholds during incremental treadmill running: relationship and reproducibility., Int J Sports Med, volume 20, issue 2, pages 122-7, Feb 1999, doi 10.1055/s-2007-971105, PMID 10190774
- ↑ AE. Kilding, AM. Jones, Validity of a single-visit protocol to estimate the maximum lactate steady state., Med Sci Sports Exerc, volume 37, issue 10, pages 1734-40, Oct 2005, PMID 16260974
- ↑ R. Beneke, Anaerobic threshold, individual anaerobic threshold, and maximal lactate steady state in rowing., Med Sci Sports Exerc, volume 27, issue 6, pages 863-7, Jun 1995, PMID 7658947
- ↑ Rafael da Costa Sotero, Emerson Pardono, Carmen Sílvia Grubert Campbell, Herbert Gustavo Simões, Indirect Assessment of Lactate Minimum and Maximal Blood Lactate Steady-State Intensity for Physically Active Individuals, Journal of Strength and Conditioning Research, volume 23, issue 3, 2009, pages 847–853, ISSN 1064-8011, doi 10.1519/JSC.0b013e318196b609
- ↑ RC. Sotero, E. Pardono, R. Landwehr, CS. Campbell, HG. Simoes, Blood glucose minimum predicts maximal lactate steady state on running., Int J Sports Med, volume 30, issue 9, pages 643-6, Sep 2009, doi 10.1055/s-0029-1220729, PMID 19569005
- ↑ Willian Eiji Miyagi, Jorge Vieira de Mello Leite, Alessandro Moura Zagatto, Influência da seleção dos estágios incrementais sobre a intensidade de lactato mínimo: estudo piloto, Revista Brasileira de Cineantropometria e Desempenho Humano, volume 15, issue 6, 2013, ISSN 1980-0037, doi 10.5007/1980-0037.2013v15n6p715
- ↑ H. Carter, AM. Jones, JH. Doust, Effect of incremental test protocol on the lactate minimum speed., Med Sci Sports Exerc, volume 31, issue 6, pages 837-45, Jun 1999, PMID 10378911
- ↑ 52.0 52.1 H. Carter, AM. Jones, JH. Doust, Changes in blood lactate and pyruvate concentrations and the lactate-to-pyruvate ratio during the lactate minimum speed test., J Sports Sci, volume 18, issue 3, pages 213-25, Mar 2000, doi 10.1080/026404100365117, PMID 10737272
- ↑ Megan L. Head, Luke Holman, Rob Lanfear, Andrew T. Kahn, Michael D. Jennions, The Extent and Consequences of P-Hacking in Science, PLOS Biology, volume 13, issue 3, 2015, pages e1002106, ISSN 1545-7885, doi 10.1371/journal.pbio.1002106
- ↑ T. Reilly, V. Woodbridge, Effects of moderate dietary manipulations on swim performance and on blood lactate-swimming velocity curves., Int J Sports Med, volume 20, issue 2, pages 93-7, Feb 1999, doi 10.1055/s-2007-971099, PMID 10190768
- ↑ 55.0 55.1 T. Yoshida, Effect of dietary modifications on lactate threshold and onset of blood lactate accumulation during incremental exercise., Eur J Appl Physiol Occup Physiol, volume 53, issue 3, pages 200-5, 1984, PMID 6542853
- ↑ N. Maassen, MW. Busse, The relationship between lactic acid and work load: a measure for endurance capacity or an indicator of carbohydrate deficiency?, Eur J Appl Physiol Occup Physiol, volume 58, issue 7, pages 728-37, 1989, PMID 2737193
- ↑ TM. McLellan, GC. Gass, The relationship between the ventilation and lactate thresholds following normal, low and high carbohydrate diets., Eur J Appl Physiol Occup Physiol, volume 58, issue 6, pages 568-76, 1989, PMID 2731528
- ↑ M. Gleeson, AK. Blannin, NP. Walsh, CN. Field, JC. Pritchard, Effect of exercise-induced muscle damage on the blood lactate response to incremental exercise in humans., Eur J Appl Physiol Occup Physiol, volume 77, issue 3, pages 292-5, Feb 1998, doi 10.1007/s004210050336, PMID 9535593
- ↑ RC. Davies, AV. Rowlands, DC. Poole, AM. Jones, RG. Eston, Eccentric exercise-induced muscle damage dissociates the lactate and gas exchange thresholds., J Sports Sci, volume 29, issue 2, pages 181-9, Jan 2011, doi 10.1080/02640414.2010.526626, PMID 21170804
- ↑ CL. de Barros, TT. Mendes, LÁ. Mortimer, HG. Simões, LS. Prado, U. Wisloff, E. Silami-Garcia, Maximal lactate steady state is altered in the heat., Int J Sports Med, volume 32, issue 10, pages 749-53, Oct 2011, doi 10.1055/s-0031-1277191, PMID 21590640
- ↑ T. Meyer, HH. Gabriel, M. Auracher, J. Scharhag, W. Kindermann, Metabolic profile of 4 h cycling in the field with varying amounts of carbohydrate supply., Eur J Appl Physiol, volume 88, issue 4-5, pages 431-7, Jan 2003, doi 10.1007/s00421-002-0712-3, PMID 12527974
- ↑ S. Seiler, What is best practice for training intensity and duration distribution in endurance athletes?, Int J Sports Physiol Perform, volume 5, issue 3, pages 276-91, Sep 2010, PMID 20861519