What’s Anerobic Speed Reserve (ASR) and how one can use it to better tailor an interval training session?

I find it disappointing when studies that compare methods of training, for the sake of their study design, OVERSIMPLIFY things that they shouldn’t. Kiely (2012) already pointed out that one of the greatest fallacies in sports training planning studies is assuming that average group-based trends and methodologies used by high achievers could be generalized for every other athlete. Unfortunately, coaches also tend to overgeneralize their training methodologies. One interesting instance is the creation of interval training; most coaches will take into account maximal aerobic power  (VO2max) as well as maximal aerobic speed (vVO2max) while placing their athletes into certain types of interval training sessions. In most cases, maximal ANAEROBIC speed is disregarded.

In principle, high-intensity interval training (HIIT) will use more anaerobic metabolism than continuous training, and that’s one of the reasons HIIT enables athletes to improve their speed (Buchheit et al, 2013). Furthermore, the high inter-individual variability in time to exhaustion (tlim) at VO2max speed (vVO2max) (Hill et al, 1996, Billat et al, 1994) as well as the poor relationship between tlim and max aerobic capacity (Billat et al, 1994) and stronger relation with anaerobic capacity (Blondel, et al, 2001), suggest that anaerobic metabolism plays a bigger role than VO2max at intense exercises aiming to improve vVO2max.

Athletes can have similar vVO2max, but completely different truly maximal speeds (or maximal anaerobic speeds). The difference between the true maximal speed and the vVO2max is called Anaerobic Speed Reserve – AnSR or simply ASR (Blondel et al 2001). In order to make it more clear I created an example (figure below) that displays three hypothetical athletes with different capabilities: 1 and 2 have exactly the same maximal aerobic speed (AeS1 = AeS2 = 21km/h), but different maximal speeds (28 and 24km/h, respectively) as well as anaerobic speed reserves (AnSR1 = 7 and AnSR2= 3, respectively).  Athlete number 3 has a lower aerobic speed (AeS3 = 19km/h), but a greater anaerobic speed (26km/h) and AnSR (7km/h) than athlete #2. While planning interval training for these three athletes a coach should have in mind that athlete 1 could and should go faster than athlete 2 in order for both to train at the similar intensities. Whereas athlete 3 could also go faster than 2 but since the latter has a higher maximal aerobic speed, athlete 3 may train at higher relative intensity than 2, specially if both run intervals at 21km/h.  Finally, if a coach wanted to intensify interval training for athlete number 1 he would have a “lot of room” to speed up (7km/h), while athlete number 2 not as much (3km/h). An experienced coach would notice that and when athlete 2 ceased of improving speed, he could try to intensify HIIT by decreasing pause in between bouts. The only way to assess these “reserves” is to first obtain vVO2max, and then to test each athlete’s maximal speed at different shorter distances, e.g. 400m – to infer on anaerobic glycolytic capacity, and 100 or 50m  -to infer on ATP-CP capacity; AnSR = Max Speed  – vVO2max.



Although different models of exercise training have been studied they tend to oversimplify things and invariably disregard inter-individual differences for the sake of generalizations. Interval training is a good example of that; where coaches use individual vVOmax at the most in order to tailor duration/intensity of HIIT to their athletes. Anaerobic capacity and maximal speed are highly correlated with time to exhaustion and also performance in interval training; athletes with similar VOmax can have completely different anaerobic capacities. Coaches ought to test these capacities (i.e. AnSR) in order to suggest better-tailored interval training sessions to their athletes.



Billat V, Renoux JC, Pinoteau J, Petit B, Koralsztein JP. Times to exhaustion at 90, 100 and 105% of velocity at VO2 max (maximal aerobic speed) and critical speed in elite long-distance runners. Arch Physiol Biochem. 1995 May;103(2):129-35.

Blondel N, Berthoin S, Billat V, Lensel G. Relationship between run times to exhaustion at 90, 100, 120, and 140% of vVO2max and velocity expressed relatively to critical velocity and maximal velocity. Int J Sports Med. 2001 Jan;22(1):27-33.

Buchheit M, Laursen PB. High-intensity interval training, solutions to the programming puzzle: Part I: cardiopulmonary emphasis. Sports Med. 2013 May;43(5):313-38.

Hill DW, Rowell AL. Significance of time to exhaustion during exercise at the velocity associated with VO2max. Eur J Appl Physiol Occup Physiol. 1996;72(4):383-6.