High intensity short interval training

Plasma noradrenaline (NA) and adrenaline (AD) concentration of subjects at rest (CON) and following each 6-second sprint (EX) (mean ± SD, n = 12). *Indicates a significant difference from equivalent CON value (P < .05). (4)

This significant response to high intensity interval training is in contrast to that from moderate, steady state aerobic exercise, which results in only small increases in adrenaline and noradrenaline. This adrenaline response to high intensity interval exercise is an important feature of this type of training as catecholamines, especially adrenaline, have been shown to drive lipolysis (fat burning) and are largely responsible for fat release from both subcutaneous and intramuscular fat stores. Even more significantly, more β-adrenergic receptors have been found in abdominal (visceral) fat compared to subcutaneous fat suggesting that high intensity interval training may have the particular potential to lower abdominal fat stores (4).

At the same time, explosive type muscle action results in the recruitment of large motor groups.  A motor group is a group of muscle fibres that are all innervated by a single motor nerve.  Small motor groups are used for low intensity, fine movements e.g. for postural control, steady movements e.g. walking, and complex movements e.g. typing.  Large motor groups are used for high intensity, power movements e.g. lifting heavy loads, running and jumping.  Large motor groups consist of large numbers of big muscle fibres and so if you want to build muscle quickly, these are the activities that you should employ. 

• Larger, more powerful muscles use more energy even when they aren't working and therefore will burn body fat more effectively. 

N.B.: if you are already at your ideal body weight, you need to feed muscles effectively too - re-fuel with carbohydrates, for energy stores, and protein for maintaining and building the muscle fibres and their associated connective tissues.

However, no one exercise is perfect:

Compared with other regimens, such as slow, steady weight-bearing exercise e.g. walking, hiking, jogging, classic aerobic routines or resistance exercise such as body-weight training e.g. press-ups, squats, pull-ups or free-weight training, short duration interval training may not be as effective for improving bone mass or core stability.

And high intensity training should be balanced with lots of very low intensity movement in order to re-oxygenate your muscle fibres effectively.

How To Do High Intensity Short Interval Training

The best thing about this type of exercising is not only do you not require any special equipment, you also don’t need much time. The whole routine, including 3 or 4 minutes warm-up beforehand and cool down afterwards, should only take about 10 minutes.

The most important aspects of this type of training are:

Intensity factor: this is not about a brisk walk - you have to really go for it! You should be “out of breath” at the end of each sprint interval.

Duration: it’s a really short time - the intensity has to be so high that you can only sustain it for a maximum of 20 seconds. And note, as your fitness improves you will find you have to up the ante as you will find it harder to get out of breath. So at first you will find that running up a couple of flights of stairs for 15 seconds is enough to get out of breath, but after a couple of weeks you will find this too easy. Then you could try adding a back pack with a few books in it to add resistance, or you could try a different exercise such as burpees (see below for some examples of activities to try)

Recovery Interval: this is interval training so you need to stop after each 10 to 20 seconds of activity and get your breath back. Allow yourself 20 to 40 seconds of recovery time (maybe enough time to walk back down the hill or stairs if that’s what you are using). Long enough for the blood to get back in your legs!, but not so long that your heart rate completely recovers.

Repetitions: Not too many! For the average person, I recommend 4 repetitions. By the end of the fourth repetition you should be feeling like you really don’t want to do another repetition. If you feel you could do more, you have not been exercising intensively enough! 

Each routine should only take a maximum of about 10 minutes including your warm up and cool down.

Only highly fit athletes (who are also under the guidance of a coach or physio) can do up to 8 repetitions of the interval training, but it is still important to note all the above conditions to ensure the correct responses.

Post-Exercise Recovery: Only repeat this training 3 times per week (or every other day). It is important to allow your body, muscles and cardiovascular system time to respond to and recover from the interval training. Otherwise the benefits will be lost as your body will have not had time to heal and will go into a chronic stress response state: The interval training, like all types of exercise, puts acute stress on the body and your body should respond to this stress by healing in a stronger state.

High Intensity Short Interval Exercises

Ensure that you are thoroughly warmed up before performing your high intensity intervals: walk or cycle or gently jog on the spot for 3 minutes before you begin your high intensity reps.

You need to use movements that are explosive and incorporate a lot of body mass in order to reach the maximum effort level necessary:

• Sprinting up hill

• Running up stairs

• Sprint cycling

• Treadmill inclined sprints

• Squat jumps

• Burpees

• Lunge jumps

• Box jumps

• Lateral jumps

Some trainers suggest little mini routines e.g. 5 x burpees, 5 x jumping jacks, 5 x lunge jumps, however I find that this leads to excessive mental stress in trying to remember what you are supposed to be doing and therefore leads to reduced exertion levels and increased interval timings. Therefore, by all means add variety to your routines, but stick to one particular movement activity per workout/day.

If required, you can add weight to increase resistance to the exercise and therefore keep the duration timing to maximum exertion within the 20 second window. Try using a back pack filled with books or leg weights. But please take care: Add weight gradually to avoid straining muscles or injuries due to unbalancing yourself.

References

1. Gillen J, Martin B, MacInnis M, Skelly L, Tarnopolsky M, Gibala M. Twelve Weeks of Sprint Interval Training Improves Indices of Cardiometabolic Health Similar to Traditional Endurance Training despite a Five-Fold Lower Exercise Volume and Time Commitment. PLOS ONE. April 26, 2016.

2. Bayati M, Farzad B, Gharakhanlou R, Agha-Alinejad H. A Practical Model of Low-Volume High-Intensity Interval Training Induces Performance and Metabolic Adaptations That Resemble “All-Out” Sprint Interval Training. Journal of Sports Science & Medicine. 2011;10(3):571-576.

3. Tabata I, Nishimura K, Kouzaki M, Hirai Y, Futoshi, Miyachi M, Yamamoto K, (1996). "Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max". Medicine & Science in Sports & Exercise. 1996 28 (10): 1327–30.

4. Boutcher SH. High-Intensity Intermittent Exercise and Fat Loss. Journal of Obesity. 2011;2011:868305