This article on interval training is divided into five parts for easier reading: “Interval Training is always Repetition Training – not all Repetition Training is Interval Training.” (Thompson, 2010). This section of the article looks at the methodology behind interval training. Areas discussed in
this section include: Figure 1 provides
an outline of the various methods of training discussed in this article. Figure 1: Methods of training Two types of aerobic training include the continuous and intermittent methods. Both the resistance and functional methods of training have developed interval training models. Some training regimens, such as Fartlek Training (Part 03, Section 3.3), combine both continuous and interval approaches. 2.1 What is Continuous Training?“Continuous training involves continuous activity without rest intervals. This can vary from long, slow distance (LSD) training to high-intensity endurance training.” (Kenney, Wilmore & Costill, 2012, p.222). The continuous method, more commonly known as continuous training, is any type of physical activity/exercise without rest intervals – it is often contrasted with the intermittent method and is generally viewed as a traditional method of training. It is also known as (not an exhaustive list) continuous exercise, continuous moderate exercise (CME), continuous cardiovascular exercise, steady state run, long steady/slow distance (LSD), and (traditional) endurance training. Continuous training requires sustained, steady state aerobic exercise and, because of its submaximal nature, may continue for a considerable time in relative comfort – distance rather than speed is the main objective of continuous training. This makes LSD training ideal for people beginning an exercise programme or wanting to reduce excess body fat. “LSD training became extremely popular in the 1960s. [and was] introduced in the 1920s by Dr. Ernst Van Auken, a German physician and coach…” (Kenney, Wilmore & Costill, 2012, p.222). Continuous training can be performed at one of three intensities:
Sometimes referred to as low-, moderate- or high-intensity aerobic continuous exercise (LICE, MICE and HICE respectively). Elite endurance athletes overload the cardiovascular and energy transfer systems using continuous exercise training at nearly the same intensity as competition. This specifically activates the slow-twitch muscle fibres in sustained exercise. A champion middle-distance runner may run 5 miles continuously in 25 minutes during workouts at a heart rate of 180 beats per minute; this pace does not exhaust the athlete but still nearly duplicates race conditions. By finishing each exercise session with several all-out sprints stopped 30 to 40 seconds before exhaustion, the athlete also trains the short-term anaerobic system (glycolysis) that contributes to race performance, particularly at the finish. A marathon runner trains as a slightly slower pace than a middle-distance athlete to simulate the intensity, distance and energy requirements of actual competition. Exercise methodologies noted as suitable for continuous training include (not an exhaustive list):
2.2 What is Repetition Training?“Let’s first take a quick look at traditional ‘Repetition Training’, since all interval training is a specific type of repetition training. You are aware that coaches and athletes frequently use repetition training by breaking training distances down into parts, with the parts being repeated, hence ‘Repetition Training’. A typical, simple repetition session might be 15 repetitions of 400m, which would be referred to as a ‘400m rep session’ or doing ‘400m reps’.” (Thompson, 2010). With classic repetition training the recovery period, unlike other forms of interval training, is long enough for the athlete to get their ‘breath back’. As such, a longer recovery period is required (e.g. 4-6 minutes) unlike newer forms of interval training where the recovery period maybe reduced to 2-4 minutes or even less than 60 seconds. “Researchers, coaches and athletes have a variety of concepts of interval training, the only point of agreement being that interval training involves alternating bouts of exercise and recovery.” (Daniels & Scardina, 1984, p.327). With this in mind, just as there are a variety of alternative names for interval training, there are a variety of definitions, including:
“The idea that interval training can be identified by a specific intensity, duration, or number of exercise bouts or by the amount or type of recovery between bouts of exercise is not valid. Rather, interval training has come to mean any type of intermittent training which, with manipulation of the number, intensity and duration of work bouts and amounts of recovery, is used to produce a particular type of stress on the body.” (Daniels & Scardina, 1984, p.327). Saltin et al. (1976, p.23-51) suggest that – using an interval training of 3 minutes at 100% of the minimal velocity associated with the maximal oxygen consumption (vVO2max) determined in an incremental test interspersed with 3 minutes at 50% vVO2max – interval training has the following characteristics:
In summary, periods of intense activity interspersed with moderate to low energy expenditure characterise many sport and life activities. Interval training simulates this variation in energy transfer intensity through specific spacing of work and recovery periods. With this approach, an individual trains at an inordinately high exercise intensity with minimal fatigue that would normally prove exhausting if done continuously. Rest-to-exercise intervals vary from a few seconds to several minutes depending on the energy system(s) overloaded. There are a number of factors or variables which help to formulate the interval training session as outlined below. 2.4 The Training VariablesThere is general agreement that rather specific guidelines are available which determine the amount and intensity of work and the amount of rest necessary to produce specific results, and it is suggested that types of training be identified based on the specific characteristics of each particular type of training rather than placing all types of intermittent training in an all-inclusive category called ‘interval training’. In other words, the training should be specific to the athlete and their sport. With this in mind, when undertaking interval training, many would suggest there are four variables to consider, easily remembered by the mnemonic DIRT:
McArdle, Katch and Katch (2006, p.457) utilise slightly different phrasing, but mean the same thing:
Kenney, Wilmore and Costill (2012, p.221) note six “primary variables” to consider:
Billat (2001a, p.15) presents ‘variables’ through a classification system “…of the different types of interval training according to the specific velocities of a race, the time limit at these velocities and ‘physiological velocities’: the velocity at maximal oxygen uptake (VO2max), the critical velocity (i.e. the asymptote of the velocity-time limit relationship), and the velocity at maximal lactate steady state.” For most people, running continuously at a 4 minute mile pace will exhaust them within a minute due to rapid lactate accumulation. However, running at this speed for only 15 seconds followed by a 30 second recovery interval enables a person to accomplish 4 minutes of running at this near record pace. Of course, this does not equate to a 4 minute mile, but during 4 minutes of running, the person covers a one mile distance even though the combined exercise and recovery intervals require approximately 11 minutes 30 seconds. Further, the variables are interrelated, and changing one will affect the others and even the training effect/output. Understanding how these variables and the training output interact will enable a person to modify their workout to their advantage. As a practical example, a person could complete eight repetitions of 400 metres in 90 seconds with a 2 minute recovery interval (8 x 400 @ 90; 2). To increase the difficulty of this interval training session a person could make four changes to the above variables (although it is wise to only alter ONE of them at a time):
In contrast, if the original interval training session was considered too challenging, changing any of the variables the other way would make it easier to complete. As a final thought, the shorter the distance a person runs, the faster they can run the total distance of the workout. For example, 5 x 1,000 metre exercise intervals with recovery intervals can be ran faster than 5,000 metres continuously; 10 x 500 metre exercise intervals with recovery intervals can be ran faster than 5 x 1,000 metres; and 20 x 250 metre exercise intervals with recovery intervals can be ran faster than 10 x 500 metres. “Exercise duration is probably the most appropriate variable to manipulate initially, building the exercise session by 10%, or 5 to 10 minutes every week or two over the first 4 to 6 weeks. Thereafter, and once adherence is developed, progressions can be implemented by increasing exercise frequency and then exercise intensity, but the progressions should always remain consistent with the individual’s goals.” (Porcari, Bryant & Comana, 2015, p.391). With so many possible combinations of these variables, there is nearly unlimited potential to vary workouts and ‘never get bored’. Although runners tend to pay more attention to the pace and distance of each running period, the benefit from interval training sessions occurs from a combination of running and recovery. The recovery intervals are very important to the design and effectiveness of the workouts. That combination of running and recovery is what makes interval runs different from continuous runs. 2.5 Determining Your Correct Interval Training Pace“Brief, all-out exercise interspersed with recovery represents a specific application of interval training for anaerobic conditioning.” (Katch, McArdle & Katch, 2011, p.432). There are a number of different ways to determine an individual’s ‘correct’ interval training pace, with three examples using distance, VO2max and rate of perceived exertion given below. Further, an individual may perform a single-paced or multi-paced session. Katch, McArdle and Katch (2011, p.435-436), referencing Fox and Matthews (1974), suggest the following distance method is appropriate for determining a person’s correct interval training pace for running and swimming:
Another method of determining a person’s correct interval training pace is through VO2max pace – the maximum volume of oxygen your muscles consume per minute (or how efficiently your body uses oxygen). The Cooper VO2 Max Test is an aid to determining a person’s VO2max.
To improve VO2max, running faster than VO2max pace is not any better than running at VO2max pace; doing so adds more fatigue, causing the current or next training session to suffer. Rate of perceived exertion (RPE) is for those who do not use heart rate monitors, or other technology, and wish to rate their training effort by ‘how it feels’. Further information can be found here. Regardless of the method an individual uses to determine their correct interval training pace, they should not run the first exercise interval of the training session so fast that they cannot match that pace during the rest of the session. Finally, the pace desired will be affected (amongst other factors) by the individual’s sport/event and motivation level. 2.6 The Recovery Period“Anaerobic and aerobic power training programs are designed to train the three metabolic energy systems: ATP-PCr system, anaerobic glycolytic system, and oxidative system.” (Kenney, Wilmore & Costill, 2012, p.223). The recovery interval (also known as recovery period or relief interval) occurs either (Katch, McArdle & Katch, 2011):
The recovery interval duration represents a multiple of the exercise interval, and is known as the work-to-rest ratio (WR Ratio) or exercise-to-relief interval (Katch, McArdle & Katch, 2011):
“The onset of fatigue, or the inability to continue exercise at a given intensity, depends on fitness level and training status, exercise intensity, and environmental conditions.” (Porcari, Bryant & Comana, 2015, p.78). During the recovery interval, an individual’s heart rate declines at a proportionally greater rate than the return of blood to the heart (In other words, a lot of blood is coming back to the heart), but the heart rate drops quickly because the individual has stopped running fast. The slower heart rate allows more blood to enter the left ventricle and results in a brief increase in stroke volume (the amount of blood the heart pumps with each beat). The increase in stroke volume overloads the heart, making it stronger and enabling the skeletal muscles to be cleared of waste products quickly because of the increased blood flow to the muscles. Because stroke volume peaks during the recovery interval and because interval training sessions have many recovery intervals, stroke volume peaks many times, providing a stimulus for improving maximum stroke volume and therefore the capacity of the oxygen transport system. 2.7 Why Interval Training?“Research has shown that athletes can perform a considerably greater volume of exercise by breaking the total exercise period into shorter, more intense bouts, with rest or active recovery intervals inserted between the intense bouts.” (Kenney, Wilmore & Costill, 2012, p.220). A sound rationale forms the basis for interval training. In the example of a continuous run by an average person at a 4 minute mile pace (Section 2.4, above), the predominant energy for exercise comes from the short-term anaerobic energy pathway with rapid lactate accumulation. The individual becomes exhausted within 60 to 90 seconds. In contrast, running at this speed for 15 second intervals or less places significant demands on the immediate energy (ATP-PCr) system with little lactate accumulation. Recovery becomes predominantly ‘alactic’ in nature and occurs rapidly (The anaerobic alactic energy system provides massive bursts of energy in very short periods of time. Generally speaking, the anaerobic alactic energy system can only be dominant for, at most, 20 seconds before the anaerobic lactic and aerobic energy systems take over.). The subsequent exercise interval can begin after only a brief recovery interval. Repetitively linking specific exercise intervals and recovery intervals eventually places considerable demand on aerobic energy metabolism. “In interval training, as with other forms of physiologic conditioning, exercise intensity must overload the specific energy system(s) desired for improvement through sport-specific muscle activation.” (Katch, McArdle & Katch, 2011, p.435). One of the attractions of interval training is its measured, precise nature. Training sessions can be tailored to an individual’s current level of ability/fitness and can also provide an accurate benchmark of their fitness, enabling achievable (and competitive) goals to be set. Interval training’s repeatability facilitates comparisons of past and present performance. Manipulation of the training variables (Section 2.4) enables a great variety of sessions, with the opportunity to create a new session every time you train! Interval training sessions have a nil/low choreography level and there is no fancy footwork patterns or complicated arm movements (subject to the requirements of the sport/activity). Interval training provides an excellent cardiovascular workout and, although interval training features a high-intensity level, this can be adjusted to the individual’s fitness level, meaning each individual can work at a level of intensity suited to them. The best part about interval training is that everyone can benefit. The only real restrictions are:
2.8 Rules of Effective Interval TrainingThese ‘rules’ are aimed at the recreational exerciser rather than professional/elite athletes, although the general ideas can be applied to both.
2.9 Seeing What Happens to the Amount of Oxygen You ConsumeInterval training sessions are very demanding, but they are an excellent method for improving an individual’s cardiovascular conditioning. Figure 2 illustrates what occurs during an interval training session. Figure 2: The increase in oxygen consumption (VO2) during an interval training session
If planned right, VO2 reaches VO2max after a couple of exercise intervals, which is the goal of the workout. These workouts are difficult because your muscles are consuming oxygen as fast as they can and also relying on some anaerobic metabolism (to produce energy without oxygen) so you can hold the fast pace. Of course this is just an illustration, a beginner exerciser, for example, will generally start and progress at a lower intensity, although the principle of a rising and falling VO2max applies. 2.10 Ventilatory ThresholdExercise intensity is recognised as the most important variable factor of exercise programming to optimise maximal oxygen uptake. Echoing this is a slow, but inexorable trend, to move away from ‘antiquated’ models of percentage of maximal heart rate (% MHR) and percentage heart rate reserve (% HRR) to the concept of ventilatory threshold (VT) (ACE, 2011). Research demonstrates that HIIT builds ventilatory power (the speed and magnitude with which individuals move air into and out of the lungs). In contrast, low-intensity exercise builds ventilatory endurance (the capacity of the endurance muscles to sustain work and resist fatigue). Porcari, Bryan and Comana (2015, p.388) suggest that “Both are critical to ventilation and the delivery of adequate levels of oxygen to the muscle cells.” The American Council on Exercise Integrated Fitness Training (ACE IFT™) Model was one of the first cardio training models to adopt the VT concept, stating that research demonstrates how certain markers reflect significant events occurring within the energy pathways and with fuel utilisation during exercise. ACE (2011) describes the two VT categories:
Onset of blood lactate accumulation or OBLA is the point during exercise at which lactic acid builds up in the blood and fatigue sets in. The point when an individual “hits a wall,” so to speak. It is also known as the lactate threshold or anaerobic threshold. ACE (2011) suggests that while many cardio programmes focus on maximising caloric quantity (i.e. burn more calories per unit of time), they should also consider building caloric quantity (i.e. greater fat utilisation per unit of time and faster recoveries) – combining both “implies training your body to continue to burn fat into higher intensities of exercise.” (ACE, 2011). For an example of an ACE 2-zone training model to improve VT1 look here. 2.11 Frequency of Interval TrainingThe exact frequency with which an individual performs interval training will be person- and sport-specific. For example some track athletes may undertake one or two interval training sessions each day of training, whilst recreational sprinters may only perform one or two per week. Professional athletes will follow a specific, tailored and seasonal training programme which will most likely incorporate interval training as an integral component. Training intensity will fluctuate depending on factors such as upcoming races, altitude, season (winter versus summer) and so on. Most recreational exercisers will most likely wish to limit their interval training sessions to between one and three per week. However, they may increase the frequency for an upcoming race or event. When discussing obesity and weight management Porcari, Bryant and Comana (2015, p.676) state “Include some cardiorespiratory workouts that are of higher intensity for a shorter period. This may best be realized with high-intensity, continuous training or with interval training. To avoid physiological and orthopedic stress and injury, complete only one higher-intensity workout per week.” (Porcari, Bryant & Comana, 2015, p.676). Continue reading Part Three What are the 4 types of interval training?Now let's break down the various types of HIIT that you can do from home––Tabata, cardio HIIT, full-body HIIT, HIIT with weights, and HIIT for runners.
What is intermediate interval training?Intermediate interval running program
For this program, you'll begin by performing 3 cycles, followed by a full 1-minute rest, then repeat the cluster 2 more times. Perform each workout 3 times per week for 4 weeks. Each week add a cycle to each cluster. By week 4, you'll be performing 3 clusters of 6 intervals.
What method of training is highInterval training is a type of training exercise that involves a series of high-intensity workouts interspersed with rest or relief periods. The high-intensity periods are typically at or close to anaerobic exercise, while the recovery periods involve activity of lower intensity.
What type of training consists of short bursts of intense exercise followed by a rest period?HIIT involves interspersing short bursts of intense exercise with rest periods. The intensity of the exercise means that HIIT sessions can be as short as 15–30 minutes but provide equal or superior benefits in comparison with longer periods of moderate intensity exercise.
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