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With input from Philip Tan & M Rameshon
This article is about training smart. To take the guesswork out of training, coaches typically conduct field and/or laboratory tests to fine-tune their runners’ training programmes. Such tests can benefit both the elite and the recreational distance runners, and they serve to:
- To identify weaknesses. The main purpose is to establish clearly where a runner’s strengths and weaknesses lie. This involves identifying the major determinants of distance running performance, measuring them, and then comparing against benchmarks. A training program can then be prescribed to address weaknesses and maintain strengths.
- To monitor progress and training efficacy. By repeating appropriate tests at regular intervals, the coach or runner can evaluate the effectiveness of the prescribed training program. Serial testing provides much more information than a one-off test.
- To predict performance potential. A number of countries have enjoyed some success at identifying individuals who may be suitable for distance running based on certain antropometric and/or physiological capacities. However, talent identification is never 100 per cent accurate.
Field tests are convenient but less accurate, while the laboratory tests are more sophisticated and costly, but accurate.
Field Tests
 The most straightforward field tests are time trials of various distances. Marathon runners often use their 1, 3, 5, 10, 15, and 21 km time trials to predict their full marathon timings and monitor their training progress. Reference tables can be used to project the running time of a particular distance based on the time achieved in another distance. One such useful table is the VDOT table devised by exercise physiologist-cum-coach Jack Daniels in his book, Daniels’ Running Formula (2nd Ed, 2005, published by Human Kinetics).
Field tests can also be used to predict physiological parameters such as maximal aerobic capacity. Examples include the Cooper and Beep tests. Unfortunately, they provide only gross estimates that are of value in assessing the fitness of the general population and beginner runners; they are not accurate enough for the purpose of fine-tuning the training programmes of elite runners. The better the athlete, the higher the level of accuracy needed.
Laboratory-Based Physiological Tests
In the past, laboratory testing was the privilege of elite athletes, but with the technology becoming cheaper and more accessible, recreational runners can benefit from such services as well. Commercial labs are now available, but before running off to get yourself tested, bear in mind that these tests are worth doing only if you know how to interpret and make use of the results. It is important that you have access to an exercise physiologist, sports physician, or a scientifically oriented coach who will help translate the results to training plans.
Types of Laboratory Tests
Physiological tests can be laboratory- or field-based, direct or indirect, invasive or non-invasive. Laboratory tests have the advantage of a controlled environment whereas field-based tests reflect the competition environment better. A direct test measures the actual physiological characteristic (e.g. measuring VO2 max for assessing aerobic capacity) whereas an indirect test measures a surrogate of the physiological characteristic (e.g. 2.4 km run to reflect aerobic fitness). Direct tests are more accurate than indirect tests, but tend to be harder to conduct. Invasive tests include biopsies of muscle tissue to determine muscle type, and sampling of blood to measure blood lactate levels. Most tests, such as video gait analysis, are non-invasive.
The Big Four
There are many factors that determine how well a distance runner performs and as many tests that are available. However, the four most useful parameters to measure are maximal oxygen uptake (VO2 max), lactate (anaerobic) threshold, running economy, and video gait analysis. The VO2 max improves as we get aerobically fitter and fitter, up to a genetically determined point. From there, we can still become even faster runners by improving our lactate threshold and running economy.
Maximal Oxygen Uptake (VO2 max), measures our aerobic capacity. VO2 max refers to the maximum amount of oxygen muscles can use at the highest exercise intensity. This is similar to the engine of a car — the bigger it is, the more fuel it consumes. So if your muscles are capable of using a lot of oxygen, it indicates a higher power output from your muscles. But we need to look at the power output in relation to body mass, as you will not be fast if you install a powerful engine in a lorry as compared to a light-bodied racecar. Hence, for runners, what matters more is the relative VO2 max, which is the absolute VO2 max divided by the body mass. Elite marathoners have a relative VO2 max that comfortably exceeds 70 ml/min/kg, compared to the man-on-the-street who has an average relative VO2 max of 35 ml/min/kg.
Figure 3.1. As running speed increases, oxygen consumption increases up to a point before it plateaus.
While a high VO2 max may be considered to be a prerequisite for elite performance in distance running, it does not guarantee achievement at the highest level of sport — the VO2 max can separate the able from the less able but not a gold medallist from a silver medallist. The test is conducted on a treadmill, and the speed and gradient are stepped up in stages until you give up. As you are running, you breathe through a mask, and the metabolic cart or metalyzer measures the amount of oxygen you consume and the carbon dioxide you produce (see figure 3.1 above). The test will take about 10 minutes to complete, and you are required to go all-out. Other than obtaining the VO2 max, the test also churns out the vVO2 max, i.e. the speed at which you achieved your VO2 max. This is a very useful figure as it accurately identifies the optimal speed for the runner to do his aerobic interval training.
To ensure greater accuracy when measuring your VO2 max, choose direct measurements (as opposed to indirect measurements such as predicting the VO2 max from heart rates during running trials), use a running protocol (rather than a cycling ergometer), ensure the equipment (called a metalyzer or metabolic cart) is a reputable one, and engage a good exercise physiologist to conduct the test (see figure 3.2).
Lactate Threshold At high exercise intensities, our muscles produce lactate. We can tolerate excessive lactate accumulation only for short durations, and hence for distance races, we need to run below a certain lactate threshold. The higher the threshold, the higher the running speed we can sustain. During incremental exercise, our blood lactate initially remains at baseline levels (usually less than 2.0 mmol/L), and as running speed increases, we reach a point where the lactate rises significantly above the baseline. This is usually termed the lactate threshold (see figure 3.3). As the running speed continues to increase, we reach another critical point where there is a very rapid rise and accumulation of lactate, called the onset of blood lactate accumulation (OBLA).
Fig. 3.3. Blood Lactate at Various Speeds. As running speed increases, the lactate increases significantly above the baseline (lactate threshold 1). With a further increase in speed, lactate accumulates quickly in the blood, causing the runner to fatigue (lactate threshold 2 or onset of blood lactate accumulation, OBLA).
Blood lactate accumulation during incremental exercise tests is commonly used to evaluate the effects of training, to set training intensities and to predict performance. To conduct the test, the runner is required to complete a 30 – 40 minute testing protocol, initially run at a low speed. The speed is then increased by 1 km/hr every five minutes until the runner is unable to continue. Between each stage, the finger is pricked to measure the lactate concentration in the blood. This is plotted against the running speed to obtain the graph seen in figure 3.3.
Unfortunately, there is a lack of consistency in how the test is conducted and interpreted. Exercise physiologists may use different definitions of the lactate threshold, different running protocols, and different methods of obtaining the threshold from the lactate-workload graph.
The data obtained from a lactate testing can be used to prescribe intensities for various training purposes. Long runs for building endurance base are usually done below the lactate threshold. The pace at the lactate threshold is also associated with one’s marathon race pace. Runs to improve one’s lactate tolerance, known as tempo or threshold runs, are usually done at or slightly above the OBLA. The speed between the OBLA and VO2 max is also utilized to prescribe “cruise intervals” of distances between 1,200 m to 2,000 m.
Running Economy Running economy is typically defined as the energy demand for a given running speed, and is determined by measuring the steady-state consumption of oxygen at various speeds. Taking body mass into consideration, runners with good running economy use less energy and therefore, less oxygen than runners with poor running economy at the same speed. Often quoted as the “forgotten factor of elite running performance”, running economy has gained much attention in recent years due to the recognition that it is a better predictor of running performance than even the VO2 max in elite runners with similar level of aerobic fitness.
The test involves the runner running on a treadmill while the oxygen consumption is measured directly using a metabolic cart. The oxygen consumptions at incremental running speeds (below OBLA) are determined, to obtain the plot below (see figure 3.4):
Figure 3.4. Running economy of a runner measured on two occasions 10 months apart, showing an improvement in running economy. For the same running speed, the runner requires less oxygen.
 With serial measurements, you can overlay your current running economy curve over a previous one. If the current curve is below and to the right of the previous one, then your running economy has improved. Running economy is influenced by muscle strength and running technique.
At the elite level, running economy is usually assessed by looking at the VO2 max in ml/kg/ km at a standardized speed of 16.0 km/hr for male and 14.0 km/hr for female runners (both at 1 per cent treadmill gradient). The average VO2 max in well-trained male runners at 16 km/hr is 190 ml/kg/km.
Video Gait Analysis While a runner is on a treadmill running at race pace, his running gait is captured on video from at least two angles. The video clip is analysed frame-by-frame to look for running faults that may lead to injury or adversely affect running economy. The advantage of analysing gait on video is that more details can be picked up compared to eye-balling. Software can be used to objectively measure joint angles and displacements (see figure 3.4.).
Running technique is an important determinant of running economy, so by correcting faulty technique, running economy can be improved.
Anthropometric Measurements
Long-distance runners have among the lowest body fat mass in comparison to their respective peers from other sports. The average male and female has a body fat percentage of between 15 – 22 and 23 – 30 per cent respectively, whereas the average elite marathon runner has a percentage body fat of less than 10 per cent for male and less than 15 per cent for females.
Body composition can be measured in a number of ways. The more accurate methods, such as hydrostatic weighing and air displacement, are tedious and not often used apart from research purposes. Dual Energy X ray Absorptiometry (DEXA) involves a 10 – 20 minute full body scan. It is safe, reliable, and relatively accurate, but somewhat costly. |
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