Below is an interview with Ana Sousa on VO2 max and Vo2 kinetics. If you have any questions, please ask them in the comments. For all of Ana’s research articles, click here and for the articles discussed in this paper, see below:
1. Please introduce yourself to the readers (how you started in the profession, education, credentials, experience, etc.).
My name is Ana Sousa. When I was 6 years old I became familiar with swimming since my parents enrolled me in swimming lessons. This moment would eventually define my future options. In 2006 I graduated from Faculty of Sport at Porto University in Sports and Physical Education – Specialization in Swimming High Performance. Few years later, in 2010, I earned at that same university my Master Degree in Sports Science – Specialization in High Performance Sports, having conducted my academic thesis in Swimming. However, I started my career as a Physical Education teacher and concomitantly as a swimming coach in 2005. Currently I am just finishing my PhD, also in Porto University, during which I have worked with high level athletes from different cyclic sports, being full committed to academia.
2. You recently published an article on oxygen uptake (vo2 max and vo2 kinetics) in swimmers. How did your study measure oxygen uptake?
A crucial aspect in training evaluation and control is to provide reliable feedback to athletes and coaches. Therefore, evaluations should occur in ecologic conditions for all athletes, which mean that swimmers should be evaluated in the swimming pool. Having this is mind, the swimmers oxygen uptake evaluation performed was conducted in the swimming pool with a breath-by-breath portable telemetric gas analyser (k4b2, Cosmed, Italy) which was connected to the swimmer by a low hydrodynamic resistance respiratory snorkel and valve system (Aquatrainer, Cosmed, Italy). This apparatus was suspended over the water in a steel cable following the swimmer along the pool and minimizing disturbances of the normal swimming movements.
3. How important do you think maximal oxygen uptake is for swimmers of various distance specialties?
A sustained period of research in human exercise physiology emerged since the 1920s, and for many years VO2 max was considered as the primary area of interest in training and performance diagnosis. However, the capacity to sustain the minimum velocity that elicits VO2 max in time is a recent topic of research and has received little attention in cyclic sports. In fact, this capacity to sustain efforts at the VO2 max intensity has been described as a new criterion for duration and intensity training sets establishment. In this sense, more important than knowing the relative/ absolute VO2 max value of a swimmer is assessing the velocity that corresponds to this intensity and for how long this intensity can be sustained in time. Knowing these parameters, more than knowing the specific relative/ absolute VO2 max value, would help swimmers, particularly those who swim from 200m on, preparing themselves in the aerobic power (VO2 max) training sets.
4. The complexity of maximal oxygen measurement in swimmers has limited the research on this subject, what assumptions on maximal oxygen uptake from other sports are applied to swimming with false pretenses?
VO2 research in swimming was scarce during the first half of the twentieth century, and for several years, early studies were conducted in non-ecological swimming conditions (e.g. cycling or running) or used untrained swimmers performing at paces different from the competitive ones (sub-maximal intensities). Moreover, research was limited by the availability of technology, particularly the inability to follow a swimmer along the pool. Notwithstanding, Liljestrand and Lindhard collected expired air and other physiological parameters (eg, blood pressure and cardiac output) in a subject swimming freely in a lake. This study was conducted 2 years before Hill and Lupton in 1922 proposed the concept of VO2 max during exercise in humans (running). In this sense, even during this time, very few assumptions on VO2 from other sports were applied to swimming research. In recent years, research has progressed as technology has evolved, and new methods have been used to assess VO2 in ecologic/real swimming conditions, allowing more reliable and valid results.
5. What were the results of your study?
In the last year (2014) I was fortunate to collaborate with other excellent researchers of Physiology of Exercise. Therefore, we had the opportunity to publish some scientific papers, where swimming exercise was analysed in two of them. From the first study it was possible to conclude that performing time to exhaustion exercises from rest to 95%, 100% and 105% of VO2 max intensity do not influence the adjustment of the cardiovascular and/or pulmonary systems that determine O2 delivery and diffusion to the exercising muscles (VO2 kinetics), with the exception of the VO2 slow component kinetics metabolic profiles (higher in 95 and 100% compared to 105% intensity). From the second study it was possible to conclude that the VO2 kinetics profile in swimmers was characterized by a slower increase towards the steady state phase (higher values of the temporal constant) at 100% of VO2max intensity, compared with runners, rowers and cyclists.
6. What were the practical implications for coaches and swimmers from your study?
From the first study, the understanding how subtle variations surrounding the VO2 max intensity (± 5%) impacts on oxidative metabolism and performance from coaches and swimmers will have important implications for optimising high-intensity interval training whenever VO2 max intensity is enhanced. By presenting a slower VO2 kinetics compared with the other exercise modes, it is suggested that swimmers would benefit more from a longer duration (~90 s) of each set of exercise for optimising high-intensity interval training whenever VO2 max intensity is enhanced.
7. Do you think the results would be different if you had differently trained swimmers?
As stated in the related literature, the adjustment of the cardiovascular and/or pulmonary systems that determine O2 delivery and diffusion to the exercising muscles depends on, among other factors, the physical fitness level of the subjects. It is expectable shorter times of adjustment of the systems in highly trained swimmers, and vice versa. Moreover, the VO2 max and VO2peak values obtained in highly trained swimmers are higher compared with low-level swimmers, and they have a better capacity to maximise their energy input. Therefore, if the studies were conducted with low level athletes, the results found would possible be different in a way that the adjustment to the VO2 supply in the beginning of the exercise, as well as in the end of it (VO2 slow component), would be slower, as well as the VO2 values found would be higher.
8. How does oxygen uptake alter for different race distances and strokes?
The majority of studies conducted in the related literature have analysed the front crawl technique in short distance efforts (≤400m). The VO2 max has its physiological maximal expression in the 400m distance, i.e., the mean VO2peak value found here is similar to the VO2max value assessed through an incremental protocol until exhaustion. Therefore, it is common to find higher values of VO2 in shorter distances than the 400m, but this must be interpreted with careful since it represents the highest VO2 value found in that specific distance, not corresponding to the VO2 max of the subject. The kinetics of VO2 should be faster in shorter distances comparing to longer distances, since the intensity performed in this later would be lower. As previously mentioned, there is a paucity of data regarding VO2 assessment in other strokes. However, from the few studies available it is possible to conclude that the front crawl is the most economic technique (lower VO2), followed by backstroke, butterfly and breaststroke technique for every swimming velocities.
9. Who is doing the most interesting research currently in your field? What are they doing?
To avoid the risk of forgetting someone, I would prefer to contrast the work that has been done by many researchers in the Swimming Department of the Faculty of Sport – Porto University since the end of the last century, consolidating this way as one of the most expressive research focus in Europe. In fact, and with the collaboration of other research centres, we have been able to identify the main variables that contribute to, and hence predict, swimming performance. Considering this as highly dependent of physiological and biomechanical factors, it has been our greatest potential to assist swimmers and coaches to enhance their performance and achieve high levels fin competitive swimming.
10. What makes your research different from others?
In my opinion, the most important issue to take into account in swimming research is the respect for the ecological environment of the swimmers. Therefore, in all studies conducted, the swimmers were analysed in their natural ecological environment – swimming pool. For that, the apparatus used, alongside with the portable telemetric breath-by-breath gas analyser that allowed respiratory and pulmonary gas-exchange variables direct assessment (K4b2, Cosmed, Italy), was suspended over the water in a steel cable following the swimmer along the pool and minimizing disturbances of the normal swimming movements. The majority of swimming studies are conducted in no-ecological conditions without direct assessment of the respiratory and pulmonary parameters.
11. Which teachers have most influenced your research?
Two important teachers influenced my research: (i) Prof. João Paulo Vilas-Boas, who is currently a Full Professor at Faculty of Sport, University of Porto and he is also the Director of LABIOMEP – Porto Biomechanics Laboratory. He was a pioneer in VO2 measurement in free swimming by studying high-level breaststroke swimmers during a simulated swimming event. He analysed and quantified the relationship between speed fluctuations and energy cost in 3 variants in breaststroke technique; (ii) Prof. Ricardo Fernandes, who is currently a Professor at Faculty of Sport, University of Porto and he is also the Head of the Swimming Department of this faculty. He was a pioneer researcher in assessment of time to exhaustion tests in free swimming, analyzing swimmers of different genders and expertise levels.
12. What research or projects are you currently working on or should we look from you in the future?
As I said previously, currently I am just finishing my PhD during which I have worked with athletes of different cyclic sports, and often I am responsible for their training control. Also, I am a current Post-Graduate Student in Rehabilitation Medicine in Exercise and Sport in the Faculty of Medicine of Porto University, and therefore, in the future I intent to intervene in this important intervention area. My future project is applying for a Post-PhD in Exercise Physiology, possibly in other Europe country. Meanwhile, I will continue my research in academia.