What is Hyrox?
Hyrox is a relatively new sport spawned from competitive fitness activities such as CrossFit. Similar to CrossFit, it combines several aspects of fitness into a competitive event where individuals must compete against each other and the clock. Hyrox is unique in that there is a set number of exercises interspaced with relatively short blocks of running. Hyrox has become popular as it is relatively easier to participate in with the reduction in highly technical Olympic lifting and gymnastics, compared to CrossFit. The loads involved in most movements are much more achievable for a wider range of participant ability. With that in mind, the competitive field is wider and arguably harder to find a competitive edge in.
A large proportion of a Hyrox event is made up of running. This running is of a set distance and needs to be completed as fast as possible before progressing to the next station or exercise. A typical event lasts over 60 mins which creates a significant physiological demand to complete in good time. While some research has yet to be completed on the demands of Hyrox, it is clear that multiple physiological capabilities must be trained to a reasonable level.
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Why is Running So Important?
Running makes up the largest proportion of a Hyrox event and being a good runner can have a significant impact on overall competitiveness. We know that being able to run short distances requires a large Vo2 max as well as the ability to utilize a high percentage of Vo2 max. It also requires the ability to tolerate and clear lactate at high intensity. When we include the demands of the other exercises involved, our understanding of lactate becomes more important as many are very glycolytic in nature. Lactate production and concentration in the blood is elevated throughout the Hyrox event.
Why is Lactate Important?
Lactate was long thought of as a waste product of glycolysis which caused acidity in the muscle. You will regularly hear athletes and commentators mistakenly refer to lactic acid as a determinant of high intensity exercise. Lactic acid exists extremely briefly in the body, as hydrogen ions dissociate almost immediately from lactic acid producing lactate and a hydrogen ion. This ion reduces the pH of the muscle, but only fractionally; nonetheless, this does interfere with muscle contractile function. Lactate is a byproduct of glycolysis which allows for further processing of excess pyruvate into ATP by aerobic means in adjacent muscle fibres. In short, it is a secondary fuel substrate which can provide fuel later in the metabolic process.
The build-up of lactate is the scenario which concerns us the most. While lactate can be utilised as fuel, it needs to be processed aerobically. This means it must be shuttled to more aerobic muscle fibres and oxygen must be available for it to be metabolised. This is referred to as lactate clearance. Even at rest, we produce some lactate and it is constantly being utilised and cleared. As we increase the intensity of exercise, we produce more lactate but also metabolise more lactate. At some point, however, the production exceeds clearance and it accumulates. This is often referred to as the onset of blood lactate accumulation (OBLA) or the lactate threshold, although some of these terms are somewhat debated as to when they occur and what they should be called. You may also hear the term LT2 or anaerobic threshold being used but they simply denote the intensity from which blood lactate concentration rises exponentially.
As mentioned earlier hydrogen ions are produced too. Typically, bicarbonate in our blood picks up these ions and we expire CO2 and water vapour in an effort to buffer these from the blood and maintain the pH levels. But our muscles don’t function particularly well in an acidic environment, and a build-up of lactate also suggests that our muscle has reached its oxidative capacity. All things now lead to a limited ability for the muscle to continue to do work. The burn sensation comes from the combination of these processes and ultimately makes it much harder to do the work.
What Can We Do About It?
Threshold work typically refers to work done in and around this threshold. By working at this intensity, we teach the body to clear lactate more effectively. The more we clear, the more we can slow or manage the accumulation. We can also build both a mental and physical tolerance to the elevated lactate concentration, although this is only to a point. Nonetheless, threshold training can significantly improve our ability to work at intensity nearing lactate threshold and even slightly above. In addition, aerobic training helps us produce less lactate at lower intensity, so a combination of aerobic and threshold training has a combined beneficial effect.
Ultimately by training the threshold, Hyrox athletes can improve their sustainable running speed and ability to clear lactate as they run. This has obvious benefits for overall performance as they can cover the run segment faster and begin their next exercise with maintained muscle function. Oppositely, poor clearance means that muscle function is compromised which results in rapid progression of fatigue.
How to Test Your Threshold?
There are several ways to test your lactate threshold. The most accurate is in an exercise or physiology laboratory where exercise physiologists will use incremental tests to profile the shift in lactate concentration over a progressive ramp of intensity. This is the gold standard and is by far the most accurate method.
Some fitness watches can estimate lactate threshold but rarely produce an accurate number. Quite often these overestimate, which can be detrimental to training by promoting increases in lactate production without a concurrent development of clearance ability.
There are some DIY tests which may help estimate lactate threshold, but these can be quite inaccurate in some circumstances. For running, a 10km time trial is often a good indicator of threshold with the average pace often falling close to a measured threshold pace. This test can be accurate for some and less accurate for others. More advanced athletes will find they can sustain higher than threshold speed for the duration of a 10km run and may find that a half-marathon average is more suitable.
Perceived effort can help give some indication of threshold. Often the phrase ‘comfortably uncomfortable’ is used to describe the sensations of threshold intensity. It should feel like hard work but work that is controllable and sustainable, breathing should be heavy but very much controlled. Most would rate it an 8 out of 10 for effort. However, these measures are subjective and athletes must be relatively experienced to use these effectively. In a competitive environment it can be very hard to fully acknowledge effort when adrenaline is high.
In short, the most accurate way to truly know your threshold is to choose an expert like Atlantia Clinical Trials, who will have it assessed by a professional physiologist in conditions where accurate and consistent results can be obtained.
What is a Threshold Workout?
In order to promote the ability to clear lactate, you must give the body appropriate stimulation and allow for its response and adaptation. There are two approaches to this which appear to work particularly well.
1. Threshold Blocks
These blocks work on the ability to clear lactate at high effort and keep concentrations stable. Ultimately, they increase the effort you can sustain before exceeding threshold. They are time and intensity dependent, meaning the length of the block depends on how close you are to threshold. For Hyrox, blocks should last between 4 and 10 minutes to be most appropriate, although longer blocks are also effective.
Suggested run session: After a warmup, complete 4 times 4-6 mins at 95-100% Threshold pace with 3 mins recovery.
2. Over-unders
These are another excellent way to develop your ability to clear lactate and increase threshold efforts. These involve steady efforts below threshold, added with short efforts above threshold. The short surges cause some accumulation while the segments below threshold teach effective clearance. As the rest is incomplete these are particularly effective at recovering on the go after harder surges such as what might be experienced during the exercise portions of a Hyrox event.
Suggested session: After a warmup, complete 4 times 2 minutes and 20 seconds at approx 85% threshold pace with a 40 second surge up to 110% threshold pace, rest for 3 mins and repeat 3-4 times.
Wrap Up
Lactate and its accumulation and management are major factors in Hyrox performance. Understanding its role and how to best approach its management will have a major impact on the effectives of your training strategy. It is important not to overestimate your effort and control these sessions diligently. They are not best effort blocks. You are simply teasing the body with the threshold boundary to force it to cope and manage lactate more effectively, allowing for increased work capacity and fatigue resistance. While running sessions are the most specific, you can also use these sessions for rowing, skiing or cycling to develop your threshold and unlock an increase in your race performance. If you are serious about improving your Hyrox performances, training your threshold is a must!
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