THE ETERNAL DEBATE: LONG SLOW DISTANCE vs HIIT
“Why would you run for an hour or longer when you can achieve the same results in 20 minutes?” - is often what the advocates of HIIT training would say. This has been an especially hot topic when it comes to combat sports, as roadwork has always been an integral part of the top level fighters' training regime. Who hasn't seen the picture of Mohammad Ali hitting the pavement? Similarly, if you go to a training camp in Thailand, you’d better bring your running shoes along, as you will not escape the daily long runs before fight training. And yet, despite the long-standing success and world-class conditioning of some of combat sport’s greatest athletes throughout history, who had been known to incorporate long runs into their training, the traditional roadwork has been under attack in recent years as an ineffective way of getting in shape for a fight.
Why do you need aerobic capacity for combat sports?
Combat sports require high levels of both aerobic and anaerobic fitness, but the overall majority of the energy required for a fight comes from the aerobic energy system. Aerobic metabolism determines the upper limit of performance and the fighter’s ability to consistently repeat high intensity efforts. Recovery in between the rounds is also regulated by the aerobic system, enabling the athlete to enter each round with more energy at his disposal and maintain good technique and composure all the way into the final rounds. And so, throughout history, the great fighters have been hitting the pavement in order to improve their aerobic conditioning.
And then HIIT came along
Ever since the appearance of high intensity interval training (HIIT) there has been an endless debate whether you can achieve the same adaptations in just 15-20 minutes, as you would by running for an hour and a half. There has been a lot of research on the topic and here’s what the proponents of the interval approach argue: roadwork takes too much time and research shows that high intensity interval training is a more effective conditioning method than longer, slower, steady-state methods.
According to research, subjects in the high intensity training groups tend to make more rapid improvements in VO2 max than those who were doing longer steady-state training (VO2 max is the most commonly used indicator of aerobic capacity, the maximum amount of Oxygen that can be inspired, transported through the blood and utilised to produce energy during exercise). So why shouldn’t everyone switch to this type of training? Well, because this is not the whole picture. Almost all of these studies focused on VO2 max as the indicator of aerobic capacity and were no more than 6-8 weeks in length. Looking at any single variable on its own, does not provide an accurate reflection of an athlete’s conditioning level. Even though improvements in VO2 max were quicker in athletes who utilised high intensity training, it has also been shown that they hit a plateau much faster (after just 3 weeks) than those in the steady-state training group, who continued to make improvements throughout the study.
And for those who argue that roadwork takes too much time, I only have one thing to say: there is no shortcut to success. Improving conditioning and performance requires time and hard work. Improvements might not come as fast as with higher intensity training, but it will lead to long-term consistent increase in aerobic fitness. So as tempting as it may sound that you can achieve better results in 4 minutes, than you could in 40 minutes, you’d better take it with a pinch of salt.
The difference between the adaptations caused by higher and lower intensity training
It is beyond doubt that interval training is beneficial for improving aerobic conditioning and VO2 max. However, doing only this type of training and disregarding everything else, might lead to less than optimal results. The cardiac adaptations induced by HIIT are different that those induced by lower intensity continuous training. Longer and slower training increases stroke volume (the amount of blood the heart pumps with each beat) mostly by increasing the size of the left ventricle. As the heart fills with a large volume of blood for an extended period of time, it stretches and becomes bigger and is thus able to deliver more blood with each beat. This is known as eccentric cardiac hypertrophy. On the other hand, high intensity training induces concentric cardiac hypertrophy – rather than stretching, the heart muscle increases in thickness. This adaptation allows the heart to deliver blood with more force, leading to improvements in VO2 max. However, this comes at a price. As the heart muscle thickens, the volume of the left ventricle decreases, thus delivering a smaller amount of blood with each beat. Eccentric hypertrophy cannot be achieved with high intensity training, because once your heart rate goes above a certain threshold (around 150 bpm), the contractions become too fast for the chambers to fill up with blood. It takes a large volume of work to stimulate the heart to increase in size, and short intense sessions simply will not get the job done. For eccentric hypertrophy to occur, it takes at least 30 minutes, but ideally 60-90 minutes of steady-state low intensity work. This means that even though high intensity methods have their benefits and are highly important for overall cardiac development, they cannot replace roadwork altogether.
Additional benefits of long slow distance
Another thing to be taken into account is that training for any combat sports is already brutally demanding, so trying to sprint at top speeds and focusing only on high intensity conditioning methods on top of the already gruelling training regime, might not be the way to long-term success. On the other hand, roadwork, does not put such high levels of stress on the body. Moreover, when used properly, it can actually aid recovery, both physical and mental. Having to push yourself to your limits in every session, even if it only lasts for 20 minutes, can easily lead to burnout or below optimal performance. And since these sessions depend on the athlete giving his absolute 100% on each rep, unless you have the mental toughness of David Goggins, you might not get the benefits after all.
For me, going for a long run is not just about improving my fitness, although I definitely feel the benefits, especially when it comes to recovery between the rounds, but also clearing my head and mentally recovering from all the other training, work and life.
But doubters will remain doubters, and LSD enthusiasts, such as myself (that stands for Long Slow Distance, not the other thing) will never be convinced to give up their beloved roadwork, and so the LSD vs HIIT debate will remain open for years to come. The truth is that only by combining both higher and lower intensity methods at the appropriate times, can you achieve all-rounded, bulletproof conditioning.
Now, for those of you who are convinced by this article of the benefits of the good old fashioned roadwork, but are still reluctant to hit the pavement for some reason, in my next article I will give you an alternative option for how to do a long run without the run. So stay tuned.
"The fight is won or lost far away from witnesses, behind the lines, in the gym, and out there on the road, long before I dance under those lights" - Muhammad Ali