HIIT: Fit & trim in 25 minutes
Losing weight and achieving a slim, toned body – preferably in the shortest possible time – is a desire shared by an increasing number of people worldwide.
HIIT (High Intensity Interval Training) is a type of cardiovascular training that burns excess body fat faster and more effectively than any traditional training method. Furthermore, HIIT increases cardiovascular capacity and improves mood, thereby promoting overall well-being.
HIIT consists of short but intense workouts based on the alternation of high heart-rate and low heart-rate exercises. It is precisely the transition from moderate to high heart rates during the same bout of exercise that makes HIIT so effective.
Versatile and customisable
Extremely versatile, the HIIT method can be applied to a variety of sports activities, including training with equipment like cardiofitness machines, treadmills, stationary bikes, rowers and steppers, as well as sports like swimming, running and skiing. The method can also be tailored to individual needs. Even people with limited training, reduced mobility or heart conditions can benefit from HIIT by including it in their personalised exercise programmes.
High intensity, short time
HIIT starts with an exercise at moderate intensity – i.e. with heart rate approximately 60-70% of the maximum heart rate – for 2 minutes, followed by an immediate increase in intensity up to 80 to 90% of the maximum heart rate for approximately 1 minute before reverting to moderate intensity. This cycle can be repeated 5 to 7 times per training session; however, it should be noted that such frequencies are only suitable for healthy individuals and in the absence of contraindications.
It is advisable to start the programme with a 5-minute warm-up and follow it with cool-down exercises for 5 minutes.
The session has a total duration of 25 to 30 minutes: 5’ warm-up + 15-21’ HIIT + 5’ cool-down.
The perfect combination of aerobic and anaerobic training
During moderate-intensity intervals, HIIT exploits aerobic metabolism which prevalently consumes lipids, whereas high-intensity intervals stimulate anaerobic metabolism, resulting in the prevalent consumption of carbohydrates. This combination induces an increase in the basal metabolic rate that lasts 24 hours after the workout, effectively reducing body fat.
Proven efficacy
In recent years, several studies have proved the benefits of HIIT.
One of the first studies in this field was conducted in 1994. Tremblay et al. were able to demonstrate that a 15-week HIIT programme resulted in a reduction in body fat nine-fold greater than that obtained with other types of physical activity.
The benefits of HIIT are not limited to weight loss. In research conducted by Tjønna et al. (2008), HIIT proved extremely effective in reducing the risk and severity of metabolic syndrome.
Trapp et al. (2008) investigated the effectiveness of HIIT in reducing subcutaneous and trunk fat and relieving insulin resistance.
Recent research shows that practising HIIT 3 days a week over a period of 8 weeks results in a 10% increase in heart volume and a 12% increase in cardiac mass of the left ventricle. Such potential for improvement in cardiovascular function has led some rehabilitation centres to include HIIT in their programmes for patients suffering from heart conditions.
One of the most extraordinary effects of HIIT, however, is obtained after just a few weeks of training and consists of the increase in the number and size of mitochondria – the body’s power stations. This corresponds to a significant increase not only in the amount of energy available to the muscles, but also in terms of general well-being.
MD Stefania Mazzieri
Gianluigi Cenciai, fitness trainer and Personal coach