Very short all-out efforts (lasting less than 1 s to around 6 s) are not only dependent on the phosphagen pathway, but also partially on glycolysis [19,20]. For example, one single ‘maximal’ 6-s sprint is in fact performed with approximately half the energy originating from ‘phosphagens’ while the other half is originating from ‘glycolytic’ pathways [20]. This finding of Gaitanos et al. [20] was published more than 20 years ago, and we believe it is time to take it into account when understanding short ‘all-out’ efforts. The latter efforts are exercise bouts during which the athlete tries to reach the highest performance possible for the pre-determined effort duration [21]. Therefore, instead of calling these efforts as ‘anaerobic a-lactic exercises’, they should be called, for example, ‘short-term high intensity efforts’ or, in a shorter way, ‘explosive efforts’. These explosive efforts are performed at power outputs approximately sixfold higher than that of ‘maximal aerobic power (MAP; which is discussed in further detail below)’ [2]. Moreover, years ago, longer all-out efforts of less than 1-min duration were described as ‘anaerobic’; a claim based on (a) a theoretical equation [22] and (b) on the oxygen uptake measured during the first minute of exercise [23]. However, Spencer et al. [21], amongst others, demonstrated mixed anaerobic/aerobic contributions in different exercise durations (from 20 to 234 s) corresponding to racing distances ranging from 200 to 1,500 m. Several authors [6,7] showed that even in very short all-out field and laboratory efforts a significant contribution from ‘oxidative phosphorylation’ (which is also called ‘aerobic metabolism’) was also present [16]. In particular, this relative contribution increases further when sprints are repeated [24].
On the field, endurance efforts are often described as ‘aerobic’. However, purely aerobic exercise does not exist as long as a minimum of intensity is put into the efforts. In this context, it is incorrect to call the considered ‘gold-standard’ test used for assessing aerobic capability/fitness, i.e., ‘the maximal oxygen uptake (VO2max) test’, an ‘aerobic test’. In this regard, recent studies challenge the concept of VO2max after modifications to the test protocol allowed attainment of different VO2max values [25]. Indeed, one of the criteria for the attainment of the VO2max plateau is to reach a minimum value for Lactate of 6 to 9 mmol L−1 (depending on the authors and the age of the subjects). This clearly shows a significant participation of ‘Glycolysis’ prior to the cessation of exercise. This is not surprising, as a maximal effort at the end of a ‘VO2max test’ occurs at intensities well beyond the second ventilatory threshold (which is also described as respiratory compensation threshold [26]). Therefore, we believe that every exercise should be described for what it is specifically assessing thereby avoiding erroneously describing particular metabolic pathway(s) involved. For instance, to describe an incremental test (VO2max) outcome, one cannot speak of the ‘maximal aerobic speed’ reached, but of the ‘peak speed reached at VO2max’ or ‘vpeakVO2max’ as justly used by Billat et al. [27].
Moreover, there have been lacks of quantification of the contribution of the anaerobic energy [2] to discriminate percentage of anaerobic versus aerobic metabolism during an effort. To clarify this gap, 40 years ago, Hermansen proposed for the first time an indirect estimation of anaerobic capacity by the ‘maximal accumulated oxygen deficit (MAOD) assessment’ based on maximal intensity exercise and gas exchange measures [28]. Several years later, the MAOD method was further experimented by Mebdo et al. [17], even though this method also raises some small methodological issues (mentioned above), it is now possible to estimate anaerobic and aerobic contributions to exercise. In that regard, it has been too often suggested that ‘aerobic’ metabolism contributes to the provision of exercise energy several seconds/minutes after the start of exercise. However, Granier et al. (1995) showed that for a 30-s all-out exercise (Wingate-test, firstly presented as a way of assessing anaerobic capacity [29]), the contribution of this pathway varies from 28% to 45% of total energy production (depending on the profile of the athletes [7]), showing again a misnomer in exercise physiology/testing [2]. Furthermore, during a 400-m all-out run of about 52-s, the last 20-s of effort is performed at VO2max, showing that the activation of ‘oxidative phosphorylation’ is much faster than previously thought [21]. Today, it is accepted that the energy provision for every effort relies on the simultaneous participation of all three energy pathways with a predominant pathway working above the others [21]. Therefore, describing the efforts should not be based on their ‘physiological processes’, but rather they should be called in accordance to their duration/intensity. More specifically, for ‘all-out efforts’ (maximal effort for the pre-determined duration), we propose to call
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1.
‘Explosive Efforts’: all-out exercises with a duration of up to 6 s (predominance of ‘phosphagens’ pathway’).
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‘High Intensity Efforts’: all-out efforts lasting from 6 s to 1 min [21] (predominance of the ‘glycolytic pathway’ in addition to the ‘phosphagen’s pathway’ and ‘oxidative phosphorylation’); and finally,
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3.
‘Endurance Intensive Efforts’: exercise with a duration exceeding 1 min (predominance of ‘oxidative phosphorylation’).
For sub-maximal intensity exercise, other definitions also need to be proposed. In that regard, the paradigm of aerobic and anaerobic metabolism is in need of further research, with both systems complementing each other. In fact, ‘aerobic’ is often intended as ‘uses oxygen’, whereas ‘anaerobic’ as ‘does not use oxygen’. That’s why any misuse of the terms may lead to misleading concepts and misunderstanding for the readers, and potential mistakes on the field for training prescription. We believe that some other concepts of exercise physiology in sport science still need similar clarification, and we encourage expert colleagues to clarify these points in relevant consensus statements. This would help sport and exercise science evolve in the right direction, using appropriate terminology that helps scientists, coaches, teachers, and students to speak the same language [30].