Tag Archives: Sprint intervals

HIIT, fat loss and muscle!

High intensity interval training (HIIT) is a very popular training method. When used correctly it effectively improves cardiovascular conditioning, burns fat and promotes new muscle growth. In addition a relatively short HIIT session is sufficient to elicit substantial performance gains. Like any training method, understanding the basic physiological principles will make a big help to using it effectively. This article will explain a bit about this type of training and some of the pitfalls to watch out for.

HIIT is popular because it is time effective. An individual can burn a lot of calories in a short space of time. As the name implies it is an intense form of exercise. Our energy systems function on a simple mechanism of energy charge. The rate of energy (Adenosine Triphosphate/ATP) utilization in the muscle cell must be matched by an energy supply system. Slow rate of energy expenditure during low intensity work is supported by oxidation. Oxidation supplies a lot of energy but at a slow rate. High intensity work is supplied by the glycolysis and phosphate systems which have a much faster supply. Supply must meet the demand. There is often a slight lag between utilization and supply. This means that even during rest intervals and post exercise energy consumption is still elevated. In simple terms our metabolism is increased and we continue to burn more calories than at normal rest conditions. For this reason even though a 20min session burns, for example 500kcals, energy expenditure is raised throughout the day. A low intensity session lasting one hour may burn 800kcal with minimal elevation in metabolisms for the rest of the day. For this reason HIIT may actually burn more calories on a daily basis. This is why it is so effective at fat burning.

HIIT can also be performed with a strength endurance element, supporting a leaner physique!

HIIT can also be performed with a strength endurance element, supporting a leaner physique!

In addition, the power output which is produced during the work period of HIIT is high. Higher power output during work periods are often effective in improving your conditioning. It also helps maintain strength and power simply by utilizing larger motor units. The main issue to consider with HIIT relates to energy supply. If we cannot supply the cells with adequate energy then they become damaged. This is known as metabolic stress. A certain degree of metabolic stress or damage can be reversed. This is what promotes new muscle growth. Moderate metabolic stress during training can, at times, be quite effective for promoting hypertrophy.

If we place too much stress on the muscle cells the damage can be irreparable. The cells will begin to die. When this happens on a regular basis muscle wastage can occur. It also places the body under larger amounts of general stress which will begin to impact on our immune system. There is a large list of potential health implications that this can eventually lead to.

Preventing this scenario is relatively easy but not always something we think about. One of the determinants to energy supply is our energy store. In the case of HIIT we need adequate stores of glycogen for an adequate supply of energy. If we do HIIT in a fasted state we are putting ourselves under severe metabolic stress, as there is little energy supply to fuel it. In addition the lack of energy will dramatically reduce performance so conditioning benefits may also be lost.

The take home message is this. Fuel up for intense exercise! Low intensity exercise can be done in a fasted state as the oxidative system works effectively to provide fuel. With intense exercise such as HIIT style training, you must have some glycogen stores or glucose in the bloodstream. If you are in a totally fasted, glycogen depleted state then consume some simple sugars close to training. By doing so you can maintain high intensity and reduce cell stress. You will still achieve an elevated metabolism that promotes fat burning. You also place the cells under just enough stress to help promote hypertrophy

It is important to understand training methods as the smallest oversight can cause more harm than good. HIIT is an effective tool but if it is not adequately fuelled it loses a lot of its benefits. It is a popular successful way to train and should be used in any program. Like any training method the process is the important part. It needs to be considered and managed properly in order to see the full benefit.

Conditioning for the competitive Crossfitter!

Crossfit can seem like a daunting undertaking for many coaches. It’s not so different to other sports. It should be viewed similarly to team sports where there are multiple components required to perform. One thing I think needs to be addressed is the intensity of a WOD (Workout of the Day). Many believe that if you aren’t redlining or pushing the limits then it’s not tough enough or productive. While skill and strength work may be done at lower intensity I feel Metcons are a source of concern. They tend to neglect lower intensity steady state work. Several big names in crossfit performed poorly in the endurance style events. 2011, 2012 and 2014 had events which brought some of top competitors to their knees.

Many wondered why the “Fittest Athletes on Earth” struggled on “Weekend Warrior” style activities. Some blamed the lack of skillset, others the heat and the competition intensity. Physiologically I think there is quite an obvious answer. These athletes are over reliant on glycolytic metabolism. When you train at high intensity repeatedly you adapt to that environment. Glycolysis is the dominant energy system and it will increase in terms of capacity when training.

Oxidative metabolism can be improved when training at high intensity but only through a few mechanisms. Many processes involved in oxidation can only be improved with volume and duration. This is neglected by short high intensity type training. I believe this is a major missing link.

Our glycogen stores are relatively small and can be exhausted quite quickly. The greater our glycolytic capacity, the quicker we deplete glycogen. We cannot sustain activity of this type for long. We need an aerobic base to support our performance. Fat oxidization is a much more sustainable source of energy. The greater the oxidative capacity the higher the sustainable workload. One way to look at this is thinking of our aerobic base as our cruising speed. Our anaerobic and ATP-CP systems are our afterburner.

The following graphic shows three athletes. Athlete A has a strong base (Oxidative system), an above average anaerobic capacity (Glycolytic system) and an above average ATP-CP capacity from his HIT training. Athlete B has an above average aerobic system but relies heavily on his anaerobic capacity. His ATP-CP stores are again average. Athlete C is our average weekend warrior for comparison. Untitled While athlete A and B are quite close in their overall work capacity, Athlete A has a better sustainable work capacity. His aerobic base allows him to maintain a high work rate. Athlete B almost matches Athlete A overall, but will never be as competitive when activity is of long duration. He may be able to complete short intense workouts with similar or better performances than Athlete A, but can only maintain high intensity for a short period.

It is essential for an athlete’s conditioning that some period of his training regime include LSD style work. This ensures that he has a strong aerobic foundation to build upon. Longer duration, volume style training promotes structural changes which have great benefit to the cardiovascular system.

Athletes of any sport should never neglect their aerobic work. It may seem boring and time consuming, but it is necessary. Recent media has given LSD style training a bad name, and cast a shadow over it. While HIT style work may be very effective overall it does not cover everything. Over utilizing it or neglecting other areas will undoubtedly create weaknesses in an athlete’s physiology. In a sport like Crossfit, these small holes in an athlete’s capabilities may cost them dearly in competition.

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4 Ways to improve lactate clearance!

The accumulation of lactate is deemed to be a major determinant of performance during competition. Lactate is a byproduct of glycolysis. The accumulation of lactate in the muscle is linked with a significant degradation in contractile function and power production. Having the ability to prevent accumulation has a significant impact on the ability of an athlete to sustain performance. The onset of blood lactate accumulation (OBLA) is deemed to be the point at which its production exceeds its clearance. In order to delay this point an athlete must train to improve his ability to clear lactate during exercise. Here are four effective strategies to improve lactate clearance.

1) Long slow distance training (LSD)

Also referred to as “Steady-State” training LSD has great benefits for lactate clearance. Even though LSD is performed at low intensity it greatly improves the aerobic system. Having a strong aerobic base usually comes with good proportion of type 1 muscle fibers. Recent studies have shown these fibers to be very efficient at consuming lactate as fuel through a shuttle system which transports it from the blood into these muscle cells. LSD training in conjunction with Lactate producing activity can teach the body to consume lactate in this way, helping to prevent accumulation during higher intensity competition.

2) Threshold training

Threshold training is performed at and around the point of accumulation. This is arguably the most effective zone to train at as it is the “Threshold” at which the body can balance accumulation with clearance. Improving workload at this zone will transfer directly into sporting performance. It is considered to be the sweet spot in terms of sustainable workload. Performing volume at this zone will result in effective lactate management in the body. It up-regulates enzymes which promote the metabolisation of lactate and clearance. The body will also learn to buffer lactate more effectively using intercellular bicarbonate. These sessions can range between 3 and 10 minutes in duration at or around OBLA.

3) Tempo runs

These are somewhat of a combination of the previous methods. During a longer session an athlete will perform a series of high paced intervals spread throughout a longer interval held at a lower, sustainable pace. During these intervals blood lactate concentrations will increase. When the athlete drops eases of intensity, the body will now be able to clear lactate to manageable levels. This promotes how the athlete recovers from lactate accumulation while still exercising. This can be useful in competition where there are varied intensities throughout a race or short rest periods between bouts.

4) Sprint intervals

Short sprints result in a very rapid production of lactate as large type 2 fibers become very active. The body does not have sufficient time to respond and so accumulation occurs just as rapidly. By using short rest periods you only give the body a very short period in which to re-establish homeostasis and so it is forced to up-regulate clearance mechanisms. Training of this type not only improves clearance but also the athletes tolerance to lactate. Sessions of this type can vary in duration for both work and rest. The ratio of work to rest can be manipulated to achieve different results in terms of physiological response.

The after effects of excessive lactate accumulation during a race. Source :www.windsorstar.com

The after effects of excessive lactate accumulation during a race. Source :www.windsorstar.com

In general any activity that elevates the concentration of lactate in the blood will elicit a physiological response. Like any stress appropriate recovery is necessarily. A multi-directional approach must be taken to ensure that an athlete has an adequate exposure to lactate without over taxing the bodies recovery capacity. This can be a difficult balance and must take into consideration a number of factors including the age and background of the individual. If done correctly any individual will benefit greatly from giving focused time and training to helping improve how they handle lactate in their body.

Building the engine!

Our cardiovascular system is basically an engine. The bigger it is the more power we can produce. Like any powerful engine its performance is based on its efficiency and size. When we look at our body in terms of conditioning we should think of it like an engine. We must first build it and then fine tune it to be efficient for what we want it to do.

When we look at training we can look at it the same way. First we need to assemble the basic parts, this is the base miles in the offseason. This is what promotes the structural changes in our physiology. Our heart becomes larger and more powerful, capillarization occurs improving blood supply to the muscle fibers and in addition numbers of mitochondria increase within the cells. This process is gradual and is stimulated by large volumes of aerobic training. It is a relatively slow process but has a long lasting effect. Because longer duration is required the intensity must be relatively low in order to accumulate adequate volume without overtraining. This will gives us the foundation for our conditioning. Increasing aerobic capacity also has a vast amount health benefits associated, such as reduced blood pressure and a strong and efficient heart.

Once we build up a foundation we must then tune it. Now anaerobic style training comes into play. Anaerobic training up-regulates enzymes which promote glycolysis, the energy system utilised during high intensity. It also improves the ATP-CP energy system used during sprint type activity. The effects happen over a much shorter period of time and remain effective for a short period if training is not maintained.

HIIT has become popular because it yields results much quicker than LSD training. The issue is that the physiological changes that come from it are really only the icing on the cake. Without a strong base prior to HIT an athlete is neglecting a big part of their physiology. This is noticeable in a lot of team sports. An athlete may perform quite well at high intensity but struggle to utilise fat for fuel, causing him to tire late in a game. They also tend to recover relatively slower as their oxidative system does not have the capacity to remove lactate as effectively.

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Athlete catching breath between play. Source:http://www.rugby365.com

If an athlete wishes to have good conditioning for their sport they must build a big engine to begin with and then tune it to be suitable to their activity. Whether they use threshold work or sprint intervals to do so will depend on the nature of the sport. The point I emphasise is that a strong aerobic base should never be neglected. Regardless if the sport is an endurance sport or not a strong aerobic system will be of great benefit to most athletes as it is still a major part of their physiology.