Many athletes use lactate threshold training to improve their endurance capabilities. The theory behind the training is that working out at or above lactate threshold will gradually raise the athlete’s lactate threshold level, improving endurance performance. However, variability in measurement along with subjectivity in interpretation call into question the utility of lactate threshold as a reliable training metric.
Broadly speaking, there are two types of training techniques most endurance athletes use to increase lactate threshold: maximal steady state training, which involves exercising at a steady pace at the lactate threshold, and intervals, intense exercises above the lactate threshold interspersed with brief recovery periods in between.
Moreover, Lactate threshold training is not the same as tempo training, clarifies Running Planet. While training to increase the lactate threshold involves exercising at a faster speed than ones 10K pace, tempo training exercises are usually 15 to 45 seconds slower than this pace.
In order to train at or beyond the lactate threshold, and to ensure steady improvement, it is necessary that an athlete knows his or her current threshold value. Currently, there are two accepted methods of detection: noninvasive measurement and invasive measurement. Unfortunately, there are significant problems with both, explains the Journal of Applied Physiology.
Noninvasive detection is easier to conduct; as one example, lactate threshold is determined by measuring gas response. However, determination of lactate threshold using this method is highly subjective.
Invasive lactate threshold validations can be based on arterial, mixed venous or capillary blood samples. The main problem here is that blood lactate levels taken from these sources tend to vary; trainers and sport scientists often pay little regard to these differences.
In a study by Yeh et al., eight non-athletes were tested for lactate threshold during an exercise test using a cycle ergometer. Subjects began a 20 W/min ramp and continued until reaching exhaustion. From the very start of the exercise ramp, arterial lactate levels began to increase; however, an increase in venous lactate levels did not appear until around 1.5 minutes later. Inconsistencies were also found in lactate levels detected from gas response data collected by four independent exercise physiologists. The reviewers noted significant variability in lactate levels, with an average range of 16% for a given subject.
The conclusion the above study arrived at was that lactate threshold is not detectable using invasive methods given the variation in blood samples taken from different sources.
Lactate threshold is widely regarded as one of the most accurate training metrics for athletes. This may say more about the paucity of options available to trainers and coaches than the inherent virtues of the measurement itself.