Training in the red zone requires less oxygen and increases your anabolic threshold. Training above 92% in this zone will require short but intense maximum effort and fast energy to be able to sustain the work. This zone burns the highest total number of calories and the lowest percentage of fat calories.
This zone is beneficial to train your fast twitch muscle fibers that helps develop speed. It will maximize your oxygen uptake (VO2max), speed, efficiency, and performance. When exercising at and above 90 percent of your maximum heart rate, your breathing will be very rapid as your cardiovascular system works strenuously to provide enough oxygen and energy to your working muscles. Training at this intensity will be exhausting for your muscles and breathing.
Training in this zone is recommended for very experienced and fit athletes or individuals who are looking for short burst of interval training. When performing the high intensity interval sets, trainees will go in and out of this zone repeatedly. Your training graph will look like spikes that go up and down rapidly. For intervals of up to 10 minutes, adequate recovery is crucial. As you climb higher into this zone, heart rate recovery takes longer. This type of training should be performed at the most twice per week, should be preceded by a good warm-up, followed by a good cool-down, and generally be preceded and followed by an easier (Zones 1 / 2) day so you can obtain a high quality and effective workout.
Benefits: It effectively trains your fast twitch muscle fibers and helps to develop speed. Training in this zone will develop your lactic acid system, tone the nervous system of your muscles and requires maximal or near maximal effort for breathing and muscles. Maximizes oxygen uptake (VO2max), speed, efficiency, and performance.
Feels like: When exercising at and above 90 percent of your maximum heart rate, your breathing will be very rapid as your cardiovascular system works strenuously to provide enough oxygen and energy to your working muscles. Very exhausting for breathing and muscles. A deep unsustainable burn is felt when your heart rate is above 95%.