Fitness testing considerations: Laboratory Tests

Fitness testing considerations: Laboratory Tests

In the first of this series of articles on fitness testing we looked at the need to obtain valid, accurate, and reliable data. The importance of this cannot be stressed enough because one needs to know that the observed changes in fitness are true and not as a result of error within the testing procedures and equipment. In this second article we will look at a selection of common laboratory tests available to competitive cyclists, what they tell you, and how you can use them to set training.

Why Laboratory Testing?
They key advantage of undertaking a laboratory test is that it enables the sports scientist to quantify specific physiological responses to exercise such as changes in blood lactate, heart rate, ventilation rate and oxygen consumption. This information can then be used to set a training programme with repeated tests used to monitor the cyclist’s progress. Although laboratory tests afford greater control over data collection they are: costly and in some cases time consuming, due to finding reputable labs and experts to deliver high quality protocols. It must also be said; testing sessions aren’t representative of real world training and racing conditions as they offer a controlled environment. This is why good coaches use a combination of laboratory and field tests to gain a more balanced view of performance.

Maximal Oxygen Consumption (V02max) Test
The laboratory test that practically everyone has heard of is the maximal oxygen consumption test, commonly known as a V02max test. This test involves measuring the cyclist’s oxygen consumption (V02) using a gas analysis machine while they ride a lab bike. The resistance of the bike is progressively increased until the point of exhaustion and the V02max is determined from the highest average oxygen consumption achieved over a specified unit of time. Additional measures obtained from the test include: the maximal aerobic power (MAP), the highest power output you can sustain using aerobic energy supply; and maximal heart rate which is the highest average heart rate achieved in the test.

The significance of theV02max score is that it provides an indication of the cyclist’s aerobic conditioning i.e. their ability to deliver oxygen to the working muscle and for those muscles to consume it. Because cycling often involves riding uphill it makes sense to report the V02max score relative to body mass. A sedentary person might score a value around 40 ml/kg/min, a trained male rider from 64-70 ml/kg/min and a world class male greater than 75 ml/kg/min. The values for elite females are lower compared with men, typically in the range of 57-70 ml/kg/min. To put these values in perspective three times Tour de France winner Greg Lemond has one of the highest maximal oxygen consumptions ever recorded at 93 ml/kg/min! 9* This large range of reported values illustrates that the human body has a huge capacity to adapt to the training demands placed upon it and novices can take great satisfaction from seeing their V02max increase with regular training.

Although V02max is a good predictor of differences in cycling performance between sedentary and trained cyclists it doesn’t have such strong predictive value at the very elite levels. This is because endurance performance is determined by more than just the ability to consume large volumes of oxygen.

 

Blood lactate response to exercise
For simplicity, the terms blood lactate and lactic acid will be used interchangeably although they are not strictly the same thing. A blood lactate profile can be determined alongside V02max or in a separate test depending upon the lab’s preferred methods. The most common test involves riding a lab bike while power output is increased in a stepwise fashion, typically every 3-5 minutes in 30-50W increments. Towards the end of each workload, when the rider is nearest to a physiological steady state, a small drop of blood is obtained and analysed for lactate content. Lactate is then plotted against power output as shown in the figure below.

The rise in blood lactate over the course of the test indicates a shift in metabolism from the predominant use of fat as a fuel towards a greater reliance upon carbohydrates. You’ll notice from the figure that there are two points (discontinuities or thresholds) where blood lactate rises at a greater rate than in the previous portion of the plot. These points are termed the lactate and anaerobic thresholds, respectively, and define points where the body is under increasingly greater stress and there is a significant rise in carbohydrate utilisation.

The importance of the blood lactate profile is that improvements in endurance cycling performance are very sensitive to changes in the thresholds, more so than V02max. This is especially true in elite athletes who might see very little change in V02max from season to season but could witness significant improvements in the blood lactate response. Untrained individuals might reach lactate threshold at 65-70% of V02max while a professional rider might have to exercise at greater than 85% V02max to reach this point. This means that the same absolute workload for a professional rider feels much less strenuous than for a moderately trained cyclist.

The blood lactate response can also be used to set training intensity. Long slow distance (LSD) training is prescribed by coaches at a power output or HR that corresponds with an intensity below the lactate threshold and high intensity interval training (HIIT) is performed at intensities above the anaerobic threshold. When training is distributed such that 80% of overall volume is LSD and 20% is HIIT it is known as polarised training. There is increasing evidence that polarisation is an effective way of improving endurance cycling performance with most world class coaches organising training in this way.

 

Efficiency
Another useful submaximal measure is the efficiency of the cyclist. This is the relationship between the work performed in pedalling the bike and the energy expended to do that work. It is usually expressed as a percentage, with figures in the literature ranging from around 16-28 per cent. In general, less well trained individuals exhibit lower efficiency than their better trained counterparts. The advantage to the cyclist of having greater efficiency is that they use a lower percentage of V02max at a given workload.

Anaerobic Power and Capacity
The critical moments in bike races require highly explosive efforts: attacking to break away; sprinting to the finish line; or closing gaps in the peloton caused by weaker riders. These efforts are often quite short (around 5-30 seconds) and sometimes have to be repeated in quick succession. Consequently, it is important to train anaerobic power and capacity and to test these qualities at regular intervals.

The most commonly used laboratory procedure is the 30-second Wingate test. The cyclists is required to produce an all-out un-paced effort on a bicycle ergometer for 30 seconds from which the total work (anaerobic capacity) can be determined, as well as peak power and fatigue index (the difference between the highest and lowest power outputs).

Although peak power can be determined from the Wingate test, in reality riders do tend to pace themselves a little so it is wise to periodically carry-out shorter 5-6 second maximal sprints. An untrained male rider might achieve an average peak 5s power in the range of 10-12 W/kg compare with a world class professional hitting around 22-24 W/kg. World class females attain lesser values on account of their lower lean body mass, averaging around 17-19 W/kg.

Finally, the ability to repeatedly perform sprints is important in many cycling disciplines so it is worthwhile conducting a test that includes a series of sprints with short recovery intervals. The BMX 6 x 3s repeated sprint test with 27s recovery intervals between each effort is one such example.

This has hopefully served as an introduction to some common laboratory tests and their uses. If you are interested in monitoring your training and want to have some fitness tests then ONE PRO PERFORMANCE OFFERS a complete suite of tests, which ONE PRO INSURANCE members can book at preferential access and in many cases at discount rates.