Lactic Acid Build-up on Low Carb

An interesting study (Hofmann, Peter & Lamprecht, M & Schwaberger, G & Pokan, Rochus & Von Duvillard, Serge. (2001). Effect of dietary modifications on lactate performance curve in incremental exercise tests and blood lactate concentration during endurance exercise on the cycle ergometer – A single case study. 110. 82-87.) which looked at Lactic Acid on three diets (Normal, Low Carb, High Carb).

Aim of the study was to investigate the influence of high carbohydrate (CHO), high fat (F) and normal (N) diet on the lactate performance curve (LaPC) and blood lactate concentration (La) during endurance exercise on a cycle ergometer. One subject performed three different diets each lasting 28 days which were repeated in random order. Exercise tests were performed on 21st (graded exercise test), 26th and 28th day (endurance test at 80% of the first lactate turn point – LTP1; at the second lactate turn point – LTP2) of each dietary block.
A strong influence of diet on the LaPC was found.
High CHO diet increased La at rest and during exercise compared to high F diet and N diet. Fixed La values were strongly influenced by the diet depending shift of the LaPC. After high CHO diet submaximal performance at 2 and 4 mmol/1 was decreased compared to N and F, independent of maximal performance. In contrast, individual turn points of LaPC (LTP1, LTP2) were found independent of diet. A steady state of La was found in the endurance exercise tests at the LTP2, but dependent on the diet La steady state values varied from 3 to 5 mmol/l. The behaviour of La during all endurance exercise tests was similar to the graded exercise test and reproducible. Usual dietary interventions in modern high performance training do not allow to use fixed blood lactate values for physical performance diagnostics. Individual methods such as the lactate turn point method seem to be more valid and can be recommended.

Second Study

Another study didn’t find the same results (Quirion, A & R Brisson, G & Laurencelle, L & DeCarufel, D & Audet, A & Dulac, S & Ledoux, Marielle & Vogelaere, P. (1988). Lactate threshold and onset of blood lactate accumulation during incremental exercise after dietary modifications. European journal of applied physiology and occupational physiology. 57. 192-7. 10.1007/BF00640662.) Note this study was at incremental exercise levels and not endurance levels.

This study was designed to clarify the effects of dietary modifications on the lactate threshold (LT) and on the onset of blood lactate accumulation (OBLA) during progressive incremental exercise. Six healthy males volunteered for the study. Informed consent was obtained from every participant. The following protocol was administered to each subject on three occasions: a 48-h period of mixed dieting (53% carbohydrates, 30% lipids, 17% proteins) preceding the first exercise test, immediately followed by a 48-h period of either a carbohydrate-rich (68% CHO, 23% lipids, 9% proteins) or a fat-rich (19% CHO, 57% lipids, 26% proteins) iso-caloric diet leading to the second exercise and separated from the third test by a 12-days period. Exercise tests were conducted on an electrically-braked ergocycle, and consisted of a progressive incremental maximal exercise. Respiratory parameters were continuously monitored by an automated open circuit sampling system. Exercise blood lactate (LA), free fatty acids (FFA), glucose levels and acid-base balance were determined from venous blood samples obtained through an indwelling brachial catheter.

Peak lactate values, workload and performance time were not significantly altered by imposed diets. Furthermore, dietary modifications had no significant effect on LT, OBLA fixed at 4 mmol and ventilatory threshold.

Increased pH and FFA mobilization were observed with fat-rich diet, while CHO-rich diet markedly increased the respiratory exchange ratio (R). It is concluded that LT and OBLA are not significantly altered by fat or CHO enrichment of diets.

Another Study – Predicting Lactate Threshold

Here’s another study which allows predication of Lactate Threshold from VO2max testing (von Duvillard SP1, LeMura LM, Bacharach DW, Di Vico P. Determination of lactate threshold by respiratory gas exchange measures and blood lactate levels during incremental load work.┬áJ Manipulative Physiol Ther. 1993 Jun;16(5):312-8.)

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