It has turned out many times that high-intensity interval training (HIIT) is effective for body fat reduction. Attention – not every training of high intensity has to be interval and not every interval workout has to be in the high intensity zone (80-90% of HR max). For example, moderate pace of marching altering with jogging is an interval workout in the aerobic zone. Faster and slower pace of riding a bike – is also a kind of training in the aerobic zone (i.e. moderate intensity). Constant running at the threshold pace is very demanding for the body, it oscillates around the anaerobic transformations – but still, the work is not interrupted and it has similar intensity. If you want to start doing the most efficient interval training, you cannot forget that it's the tool mainly for the advanced ones with good aerobic endurance (followed by anaerobic endurance). If you are not able to run for 30-40 minutes outdoors in the pace of 5 minutes per 1 km (12km/h) – it's too early for you to do interval training (VO2MAX – at the maximal aerobic threshold, i.e. high intensity). On the other hand, even older untrained people can use interval training without any preparation, but it has to be underlined: low intesity training (e.g. marching in various pace in the aerobic zone, submaximal). You have to sacrifice few weeks to build proper physical condition. If you use interval exercises in your weekly plan, you cannot work out more than 5 times a week.
Possible options of including HIIT/HIRT sessions in the training plan:
threefold strength training (60-80 minutes) and twice the interval training on days free from strength training (the whole interval session lasts for 15-25 minutes),
twofold strength training (60-80 minutes), once restful jogging (30-40 minutes) and twofold intervals,
threefold strength training (60-70 minutes) + aerobic session for 20-25 minutes at once, 1x intervals on a chosen day,
twofold restful jogging + twofold intervals within this training (the whole session for 30-40 minutes), everything completed with two strength workouts,
four strength workouts (one of: PUSH, PULL, FBW, interval).
Remember, that more does not mean better. You may reach your maximal weekly load after 6-10 weeks of continual training!
Going back to the main topic – in some studies, the traditional aerobic sessions lasting 40 minutes 3 times a week does not bring any results in reducing body fat. Further study cited in the Charles Poliquin's article also presents very interesting observations.
17 trained young people took part in this experiment. There were two kinds of workouts used in this test:
traditional strength training, i.e. 8 exercises in 4 sets until breakdown, intensity of 75% of maximal load, 1-2 minutes break between sets, total volume of session: 32 sets,
HIRT (High-Intensity Interval Resistance Training) – contained 6 repetitions, 20 seconds break, 2/3 of repetitions, 20 seconds break, 2/3 of repetitions and a long break of 2 minutes 30 seconds. In general, the volunteers did 3 prolonged sets – almost like the cluster method (leg press, barbell press lying and cable chest pull); intensity: 85% of maximal load.
The experiment was about to establish the influence of each kind of work on the daily energy expenditure (the body burns it during rest – REE). REE was measured before and 22 hours after finishing the workout.
Traditional workout lasted 62 minutes, 7,835kg of load was shifted, the level of lactic acid in blood increased to 5.1 mmol/L – after workout. After 22 hours in this group there was a 5%-increase of burning calories during rest – from 1901 to 1999/day.
In the high-intensity interval training group during 32 minutes of work, the volunteers shifted 3,872kg of load and the level of lactic acid measured after workout increased to 10.5 mmol/L. After 22 hours there was a 24%-increase of burning calories from the level of 1909 to 2362/day!
As you can see, the high-intensity group did their workout in half the time of the traditional training with half of the volume. Despite that, there was the increase of 452kcal burned per day. In the perspective of 3 interval workouts per week, it would bring noticeable results. In many scientific studies it has been proven that the level of lactic acid after workout is directly connected with the release of growth hormone and burning fat. The best effects are caused by training large muscle groups (legs, back) – therefore, for example, TNT or TOMAHAWK training may be very beneficial. A well-trained person may even lift 10 tonnes in 20 minutes and over 15 tonnes in 30 minutes. In the experiment the volunteers shifted only 3,872kg in 32 minutes. It means, that you can increase the intensity of the workout by three-four times and increase the release of growth hormone. The observations noted by the Italian scientists have been confirmed in other studies many times: “it was stated that short submaximal (aerobic) workout causes slight increase of growth hormone release, whereas, high-intensity workout (with higher aerobic threshold and higher HR) causes much stronger release of GH. Resistant training (with load) influences the release of growth hormone stronger than aerobic training (running, riding a bike, swimming).”
In the next study, Trapp (2008), did a 15-week experiment among 45 young women (BMI 23.2 +/- 2.0) at the age of 20.2 +/- 2.0. The training included 3 sessions a week lasting 20 minutes. High-intensity training included 8 seconds of speed and 12 seconds of rest (slower ride) for 20 minutes. The other group of ladies did a 40-minute aerobic workout at the same time. The high-intensity group lost 2.5kg of fat, in the aerobic group there were no changes.
It has been stated in many studies that the interval training “saves” muscle tissue and aerobic training harms it. Even in some experiments the increase of muscle tissue was observed among untrained people who did regular interval training:
The Australian scientists examined the thesis on 46 obese men. All of them were over 20 years old (24.7 +/- 4.8 and 25.1 +/-3.9), average BMI was at the level of 28-29. There were no major changes in diet. Half of the men trained 3 x a week, for 20 minutes (on exercise bikes). They had a 5-minute warm-up, then 8-second sprint with the 12-second rest (40 spins per minute). The men were exercising within 80-90% of HR max (120-130 spins per minute) and they finished the workout with 5-minute cool down. The heart rate during tests was, on average, 160 +/- 9 beats per minute. After 12 weeks of training the men lost 2kg of fat (the loss of 17% of visceral fat; few cm less in waistline), they increased their maximal aerobic threshold (VO2 max) by 15% and their lean body mass slightly increased (which means increase of muscle tissue). Tha balance of body weight loss was 1.5kg. The biggest increase of muscles was observed in the area of the upper body, smaller within legs and the smallest within arms (0.4kg for legs and 0.7kg for the upper body).
If you are bored with aerobic and traditional resistance workouts – maybe it's time to look for other solutions?
6 x thrusters + 6 x pull-ups + 6 x dips + 6 x SPRAWLE, 1-MINUTE BREAK.
6 x power clean + 6 x deadlift + 6 x renegade row (for each arm) + 6 x sprawle.
Repeat the circuits until breakdown.