When programming for a series of HIIT workouts there are quite a few parameters to be played with. Broadly, they fall into two groups
- The exercises that form the basis of the training session(s)
- The interval specifications (time, rest time, repetitions)
I am currently not too fuzzed about the first point, under the assumption that (1) the main objective of doing HIIT is to increase VO2max, and to some extent the efficiency of the anaerobic pathways, and (2) that anything that jacks your heartrate up is good to improve your VO2max. Having this in mind, the exercises should be as varied as possible to avoid boredom, overuse injuries, and last but not least plateaus. Having said this, there are a number of considerations:
Firstly, for every athlete, different exercises have different constraints. As described in this WOD for example, my constraint on running is usually VO2max, not strength in my legs. My constraint on push-ups on the other hand is strength in my arms, albeit not by much, whilst on pull-ups it is strength in the arms by a big margin. This means that running is a great exercise to use in an HIIT, and push-ups also work quite well, especially in conjunction with an exercise like running so that the push-up interval is to some extent a recovery from the harder running interval as well. (Unsupported) pull-ups however dont work for me at the moment – before my energy systems are stressed I run out of power in my arms.
Secondly, the HIIT segment of the training program should support the remainder. So for example, I might not be wise to go all-out on thrusters the day before going for a PR on squats, or all-out on kettlebell swings before deadlifts. On the other hand, if the current training focus is on improving shoulder stability, then kettlebell snatches might be a great exercise to include in the HIIT sessions.
So let’s now deal with the second point, interval specifications. As already pointed out, we are really dealing with three parameters here: the time of the effort, the rest time between the sets, and the number of rounds performed. Note that we do not need to deal with intensity here, simply because of the assumption that the athlete will make an all-out effort consistent with the interval parameters, meaning that he or she will just be able to finish the final set before collapsing on the floor, “breathing fire”.
Those three parameters are however not independent, or orthogonal as a mathematician would say: doing 5 rounds (or taking a 10sec rest period) on a Tabata (ie a 20s working interval) has not the same effect as on a 2min work interval. So I have found useful for planning my workouts is the following (almost) orthogonal parametrisation:
- Length of one working set (in seconds)
- Ratio between the length of one recovery period and the length of one working set (a fraction)
- The aggregate time for all working sets (in seconds)
For example, the classic Tabata (20s work, 10s rest, for 8 rounds) would be described as 20s working sets with a 2:1 load/recovery ratio, for a total of 160s. All of those numbers can be interpreted independently in a meaningful manner in terms of the training impact they have – that was the whole point of the “orthogonalisation” exercise in fact:
- The length of the working set determines which energy system will be trained, with the two anaerobic systems being dominant at the short end, and the aerobic system (that is always trained for that matter) at the long end
- The load/recovery ratio determines replenishment of the energy systems: the shorter the recovery period in relation to the work period, the quicker the body need to replenish. There is also some impact on the energy system here (and in that sense this is not fully “orthogonal”): the shorter the breaks, the more emphasis is on the longer term systems. For example, when many rounds are performed with a 5:1 load/recovery ratio, then the overall effort is likely to become rather aerobic at the end as replenishment can not possibly happen during the short rest periods
- The aggregate time under load determines the work volume that has been done. This is equivalent to the reps x weight measure employed in programming for powerlifting (keeping in mind that the effort is a max effort) and it is well known that volume should be neither too high nor too low if adaptation is to occur.
So how do I go about putting this in practice? Easy: Firstly I decide upon the length of the working set. My favorite values are 20s, 60s, and 2min. I also sometimes do 10s, 30s, and 3-4min. However, the 10s is tough for me to do in practice (on most exercises I am not at a stage yet where I could safely put an adequate effort in for this short period – I could try sprinting outside/uphill I suppose, but in the gym it is difficult) and I believe that 3-4min is in principle too long, but I do it from time to time for the “800m” style efforts.
As a second step, I decide on a load/recovery ratio. I generally employ one of four ratios – 2:1, 1:1, 1:2, and 1:3. I do not feel it makes sense to go shorter in the rest than 2:1 as then the rounds blend into each other too much, and the effort is more continuous. At the same token I do not feel it makes sense to go longer than 1:3 as by that point recovery tends to be sufficient.
As a third and final step I decided upon the aggregate time under load. Generally I tend to do something between 2-10minutes, with the shorter work intervals tendencially getting also shorter aggregate working time. I have no particular reason for that, other than that on a typical Tabata I am toast after 2-4 minutes, whilst on 1min intervals I might last 5-8 minutes. I also adjust the time for where I am in my workouts – if I hadnt had a break for a while (or I have done or will do something else on the day) I will go shorter, and if I am fresh and/or the HIIT is the sole focus of the day then I go a bit longer.
That’s it really – not very scientific, but works pretty well for me.
Note: of course, the CrossFit TabataThis schedule takes it a bit further – there a number of HIIT sessions are performed back to back, with a controlled pause in between. Whilst this is a great way of doing this, it really only makes sense if the primary HIIT is very short, so no need to try to put this into the system. Just do it from time to time, with Tabata-style interval sessions, or even shorter, and varied rest periods.
UPDATE: In this table from the CrossFit Journal, Coach Glassmann put together an overview of the various energy systems in the body, and how to train them
|Primary Energy System||Phophagen||Glycolytic||Oxidative|
|Duration of work (in seconds)||10 – 30||30 – 120||120 – 300|
|Duration of recovery (in seconds)||30 – 90||60 – 240||120 – 300|
|Repetitions||25 – 30||10 – 20||3 – 5|