Burst is a full body high intensity workout (primarily cardio) designed to improve your running speed, your muscle stamina, and your heart and lung functions. There's also en element of resistance to strengthen muscles from a functional point of view which also helps with the desired 'toning' effect. To bring about these outcomes you'll need to push yourself out of your comfort zone attempting to perform each of the exercises to the best of your ability. The best way to track your effort is using a heart rate monitor where you can expect to achieve a workout average between 80% and 90% of your maximum heart rate.
Pushing yourself to a max effort isn't easy and it's something we get better at the more we train at a high intensity. A max effort requires exercise competence (to be well-practiced), a high pain threshold, mental toughness and determination, adequate nutrition and rest, and arguably a motivational climate that spurs individuals on to give their all.
Your body does not like being pushed, it's designed to be conservative, but it's also very good at adapting to new stimulus (i.e. increased resistance, faster running speed, more reps). Challenging the body physically will result in temporary muscle pain (burning sensation), breathlessness, thirst, and an increased body temperature. In some cases you may feel slightly nauseous or light headed as blood is being diverted to the working muscles to meet the increased demand for oxidative energy metabolism.
The frequency or how many times your body is exposed to the training stimulus is also important. If you're new to training, once a week can be sufficient for initial improvement. If you're wanting to carry on improving you would need to increase the frequency of your training up to 3-4 times a week but it depends how far you want to progress with your training, and what you're training for. For example studies have shown that the health benefits of cardio exercise taper off after 3 sessions a week. With an average of 2 intense cardio sessions a week giving you the biggest bang for your buck when it comes to having a healthy circulatory system.
High intensity interval training (HIIT) will help you burn more calories, however you shouldn't concern yourself with how many calories you're burning from exercise. Believing exercise alone will make you lose weight is a common misconception. The best way to lose weight is to create a calorie deficit by reducing your food intake whilst eating a balanced diet including all food groups. Exercise will certainly complement your weight loss journey but the primary motivation to exercise should be for better health and well-being. We don't need to starve ourselves either, diet intervention studies show that a moderate calorie deficit (200-400 kcal less than your daily energy requirement) is more sustainable meaning you're more likely to lose weight through gradual changes to your diet than drastic short term measures (i.e. crash diets). In addition, people who do lose weight are more likely to maintain their new weight when exercising alongside a reduced calorie diet.
There are four parts to each round of Burst - treadmill running, resistance exercises using weights and the cable machine, high intensity exercises including boxing and cardio machines, plus bodyweight and core exercises on the mats.