What is a blood lactate test?

A blood lactate test is an incremental step test performed on a cycle ergometer during which small samples of blood are collected and analysed to dertemine the conentration of lactate in the blood at the end of each stage. The data obtained from this procedure is then plotted on a graph and analysed with a software program to identify the workload associated with the start of an exponential increase in lactate concentration above baseline levels - the lactate threshold (LT). This threshold is an excellent predictor of performance in endurance sports and changes in the threshold over time can give insight into the effectiveness of a training regime.

The test is performed on your own bike mounted on the Computrainer and involves a standardised warm-up before undertaking an incremental step test in which the resistance is increased by a set amount every 5 minutes. Initially the test is quite easy, but once you exceed your lactate threshold you will begin to rapidly accumulate lactic acid, making the later stages of the test quite hard. Small blood samples are taken from the ear lobe or finger tips in the last 30 seconds of each stage and are analysed by a lactate analyser. Overall the test takes approximately 1hr but allow 1.5hrs when booking to accomodate setup time. Following the test the data is downloaded from the lactate analyser to a PC where special software plots the information on a graph (see below) and calculates an approximate LT. 

Background

Lactic acid is a byproduct of anaerobic glycolysis (the process of breaking down of glucose for energy in the abscence of oxygen) and it's acculmulation within the muscles and bloodstream interferes with the ability of muscles to contract forcefully. At any given time your body is using a mixture of anaerobic (without oxygen) and aerobic (with oxygen) energy systems. At low intensities the aerobic system predominates, however, at higher intensities the aerobic system is unable to satisfy the energy demands of the activity and your body must increase the relative proportion gained from the anaerobic system. This is fine up to a point but at high enough intensities your body is unable to process the extra lactic acid being produced and it begins to rapidly accumulate, thereby limiting the time that higher inensities of exercise can be maintained. 

Why do a blood lactate test?

Research has shown that the best predictor of performance in endurance sports such as cycling is the LT. The cyclist with the highest power output at LT is the one who will perform the best (all other things being equal) because he or she can work for extended periods of time at this level without accumulating excessive amounts of lactic acid. By analysing the data valuable information can be gained regarding aerobic and anaerobic conditioning. Monitoring repeated test results over time gives good physiological feedback on howeffective your training is and can detect signs of overtraining.

Setting power/HR training zones

Blood lactate testing has often been used to help set training zones, however, I have found from practical experience that it is difficult to be precise as what the graph tells you and what a cyclist perceives to be threshold can often be quite different. What a cyclist perceives to be threshold is probably more closely associated with another term called the maximum lactate steady state (MLSS) which is the highest workload that can be maintained without a continous increase in lactate concentration. This means that at and just below MLSS the rate of production and removal of lactate in balance, although the lactate concentration in the blood will be significantly elevated above baseline. A blood lactate test is not a steady state test as the workload increases every 5mins, so while it can tell you the workload that corresponds to a significant increase in lactate in the blood it can't precisely tell you the point at which the rate of lactate production exceeds the rate of removal. 

Luckily, MLSS is closely correlated with 30min time-trial performance and so an alternative test can be used (see Power/HR Zone Testing below).

For further information on blood lactate testing see www.lactate.com  

• Cost - $130 per session or $330 for 3 pre-purchased sessions (to be used within 12 months)
  

Having accurate training zones to guide you is essential to success in cycling. This test detrmines your power and HR at threshold and training zones are calculated from there. The test involves a 30min all out time-trial is performed on the Computrainer following a standardised warm-up. The average wattage held over the 30mins closely approximates the power you could maintain for a 1hr timetrial under race conditions (usually wihin ~3-5%) and also correlates closely with the MLSS as described above in the blood lactate section. Your threshold HR is calculated by taking the average HR during the last 20mins of the 30min effort and HR training zones are calculated from there. Power and HR zones are calculated by analysing the test data with CyclingPeaks WKO+ software.

Testing takes ~1hr with warm-up included.

• Cost - $88