There has been a large amount of research looking at the effects of different interval training sessions. Most of this has looked at the effects of factors such as intensity, duration, volume, and recovery periods (active recovery, passive recovery, work to rest ratio etc). Whilst this has given us great insights into how to structure interval training, to maximise the performance benefits, it is not clear whether all athletes gain the same the benefit, from these training sessions e.g. should highly trained and moderately trained athletes, be performing intervals at the same relative intensity, and utilising the same recovery periods.
A recent study, published in The Journal of Sports Medicine and Physical Fitness, looked to resolve one of these issues, by looking at the effects of aerobic fitness, on total time spent at a high percentage of VO2max, during high intensity interval run training (Panissa et al., 2014). To assess the effects of aerobic fitness on the interval session, the researchers got athletes to perform intervals consisting of 1 minute at vVO2max, separated by 1 minute of passive recovery. The researchers then looked at how much time the athletes spent above 90%VO2max – this is a key intensity, since research has shown that to gain the greatest aerobic benefit from interval training, athletes should train at an intensity between 90 and 100% VO2max.
The main finding of the study, was that the athletes with a high VO2max, spent significantly less time above 90% VO2max, despite training at the same relative intensity, as the athletes with lower aerobic capacities. The main reason for this, is likely due to the way that athletes with a greater aerobic capacity, are able to recover more effectively during recovery periods, and therefore spend less time at a higher VO2, throughout the interval workout. This is an important finding, and suggests that athletes with a higher aerobic capacity (higher VO2max), should utilise shorter recovery periods, than athletes with lower aerobic capacities, in order to increase the overall intensity of the workout and ensure that they spend adequate time with a high rate of oxygen consumption.
Implications for training:
The main implication, is that for athletes with a high VO2max, a work to rest ratio of 1:1, does not appear to be optimum for maintaining a sufficient oxygen uptake throughout a vVO2max interval workout. In order to increase the oxygen uptake, athletes with a high aerobic capacity may need to reduce the recovery portion of training or utilise a more active recovery. The same is likely true for intensities just below VO2max (e.g. 5k and 10k pace intervals) and highlights how group interval training may not always be effective, even if the athletes are of similar abilities – e.g. if two athletes have a similar 5k race time, but one has a greater aerobic capacity, then the athletes would run the 5k intervals at the same pace, but the athlete with the greater aerobic capacity, may need to utilise shorter recovery periods, to gain the most from the interval training.
For me the recovery period has always been an important, and often overlooked, part of interval training. I always feel it’s important to push the recovery, to the minimum recovery time, that still enables you to maintain the target interval speed. This can be a case of trial and error at first, so the best approach is to gradually reduce the recovery time, by a small amount each week – you’ll soon know if you’ve reduced it too far as you won’t be able to maintain the target interval pace. Reducing the recovery time, is the best way to increase the overall intensity of the workout, and ensure a greater aerobic benefit. In addition, it forces you to run the intervals at a more controlled pace, which is great for pace judgement.
Panissa VL, Julio UF, Pinto-E-Silva CM, Andreato LV, Schwartz J, Franchini E. (2014) Influence of the aerobic fitness on time spent at high percentage of maximal oxygen uptake during a high-intensity intermittent running. J Sports Med Phys Fitness. 2014 Dec;54(6):708-14.