From Lab to Trail: How to Maximise Potential with Running Physiology Tests
By Doug Stewart, Performance Coach & reviewed by Meg Smith, Physiologist
The ETT Athletes have benefited from physiological testing to provide insights into their running, but what are they and what are the benefits of doing them?
The running physiology test comprises two parts: the sub maximal effort and the maximal effort. These help the support team understand the athletes’ physiology better. The results assist the coaches in understanding how the athletes are producing the running speeds and how various elements of their physiology interact with one another.
Sub-Maximal Running Test
The sub-maximal test is used to identify the blood lactate curve of each athlete and their running economy. Whilst there is much debate around the terminology and use of lactate thresholds or turnpoints (a great overview is provided in this video by Dr Mark Burnley), the primary aim of the blood lactate testing is to help define the intensity domains for each athlete.
A typical blood lactate curve showing increasing blood lactate with increasing work intensity (run speed) with the intensity domains divided by ‘thresholds’
Source: Faude et al., 2009
The results from these tests will help ensure that the athletes are training at the correct intensity and will also support improvements in the quality of their training. Various testing procedures exist, such as varying durations of the stages in an incremental test and modifying the testing protocol. The data analysis may impact the results, which – in turn – could impact the assessment of the various intensity domains (Bentley et al., 2007). Additionally, the type of device being used to assess blood lactate will have an impact on the accuracy and validity of the results (Bonaventura, 2015). Therefore, to ensure more valuable results are achieved, it is important that the testing protocol and the equipment being used, plus the practitioner using it, are relevant / appropriate for the athlete population being tested. The ETT Athletes were tested at Loughborough University, with a team who are very experienced at working with high standard runners, understanding the demands of trail and ultrarunning, and using industry leading equipment.
In addition to blood lactate, the athletes’ running economy was also assessed in the submaximal test. Running economy is a measure of the oxygen consumption at a certain running speed and represents the energy requirement for maintaining the submaximal running speed (Barnes & Kilding, 2015). It is seen as a key element of running performance, although for trail and ultrarunning it appears to be less of an indicator of performance in races, compared to the case of road runners (Coates et al., 2021, Pastor et al., 2022). Having said that, some studies show that there are no clear indicators linked to performance in 100-mile ultramarathons for aerobic fitness, running economy or any training variables (Coates et al., 2021), which suggests variables other than physiological factors come more into play the longer the race is. Other research has shown that running economy on a 10% slope did relate to performance at the 100-mile Ultra-Trail du Mont Blanc (Pastor et al., 2023). Additionally, an improved running economy relates to a lower energy demand at a given speed, which may help with GI issues, thermal regulation and other factors that do directly link to trail and ultrarunning performance.
Maximal Running Test
The maximal test assesses the athletes’ V̇O2 max, the maximum amount of oxygen the athlete can consume and use within 1 minute. This is typically shown as millilitres per kg of bodyweight per minute (Buttar et al., 2019). V̇O2 max is a good indicator of performance for runners over shorter races, and whilst traditionally thought not to be as relevant for longer ultramarathons, a recent piece of research did suggest it was a factor that influenced performance in the UTMB (Pastor et al., 2023), which was a novel finding.
By understanding the athletes’ intensity domains and their V̇O2 max, the relative strengths and limiters can be identified to help inform training prescription. For example, fractional utilisation refers to what % of V̇O2 max the threshold occurs at. LT1 becomes limited at 80% VO2max, with LT2 becoming limited at 90% VO2max, hence if an athlete’s fractional utilisation is approaching these limits, it would suggest that they would need to work on maximal capacity in order to create further room to progress. Endurance at each threshold could be used to assess where the athlete currently is in comparison with the goal they have in mind, and therefore inform the training they need to do in order to achieve that.
Fuel Utilisation
During both tests, the athletes are wearing a face mask to capture inspired oxygen and expired carbon dioxide data. This provides insights into the amount of carbohydrate and fat they are using at varying intensities. Fat and carbohydrate serve as substrates for energy metabolism during exercise and the percentage of contribution of each of these is influenced by the intensity of the exercise, in addition to factors such as pre-exercise diet and training status (Bergman and Brooks, 1999). During the submaximal test, with the speed increasing, the relative contribution of fats to carbohydrate will change. Generally speaking, at intensities below and up to LT1, fats are the predominant source of fuel. As intensity increases beyond LT1, towards LT2 and VO2max, carbohydrate becomes the body’s predominant fuel source.
This allows coaches and dietitians to understand how each athlete is fuelling the work. Similar to the lactate testing, the quality of the equipment can have a significant impact on the accuracy of the results (van Hooren et al., 2023), so again, using a lab with high quality equipment should help with accuracy.
However, there will always be a margin of error with any testing. In addition to elements such as the shoes being worn, a faulty heart rate monitor battery or the breakfast the athletes ate, it is important to review the results from these tests, scrutinise them and use informed judgment on how they will be used to guide training and nutrition plans.
References:
Barnes, K. R., & Kilding, A. E. (2015). Running economy: measurement, norms, and determining factors. Sports medicine-open, 1(1), 1-15.
Bentley, D. J., Newell, J., & Bishop, D. (2007). Incremental exercise test design and analysis: implications for performance diagnostics in endurance athletes. Sports medicine, 37, 575-586.
Bergman, B. C., & Brooks, G. A. (1999). Respiratory gas-exchange ratios during graded exercise in fed and fasted trained and untrained men. Journal of applied physiology, 86(2), 479-487.
Billat, V. L., Hill, D. W., Pinoteau, J., Petit, B., & Koralsztein, J. P. (1996). Effect of protocol on determination of velocity at VO2 max and on its time to exhaustion. Archives of physiology and biochemistry, 104(3), 313-321.
Bonaventura, J. M., Sharpe, K., Knight, E., Fuller, K. L., Tanner, R. K., & Gore, C. J. (2015). Reliability and accuracy of six hand-held blood lactate analysers. Journal of sports science & medicine, 14(1), 203.
Burnley, M., & Jones, A. M. (2018). Power–duration relationship: Physiology, fatigue, and the limits of human performance. European journal of sport science, 18(1), 1-12.
Buttar, K. K., Saboo, N., & Kacker, S. (2019). A review: Maximal oxygen uptake (VO2 max) and its estimation methods. Ijpesh, 6(6), 24-32.
Coates, A. M., Berard, J. A., King, T. J., & Burr, J. F. (2021). Physiological determinants of ultramarathon trail-running performance. International Journal of Sports Physiology and Performance, 16(10), 1454-1461.
Faude, O., Kindermann, W., & Meyer, T. (2009). Lactate threshold concepts: how valid are they?. Sports medicine, 39, 469-490.
Pastor, F. S., Besson, T., Varesco, G., Parent, A., Fanget, M., Koral, J., ... & Millet, G. Y. (2022). Performance determinants in trail-running races of different distances. International Journal of Sports Physiology and Performance, 17(6), 844-851.
Sabater-Pastor, F., Tomazin, K., Millet, G. P., Verney, J., Féasson, L., & Millet, G. Y. (2023). VO2max and Velocity at VO2max Play a Role in Ultradistance Trail-Running Performance. International Journal of Sports Physiology and Performance, 18(3), 300-305.
Van Hooren, B., Souren, T., & Bongers, B. C. (2023). Accuracy of respiratory gas variables, substrate, and energy use from 15 CPET systems during simulated and human exercise. Scandinavian Journal of Medicine & Science in Sports.