This content is from the experts at Men's Fitness magazine.
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Doing steady-state cardio exercise a few times a week is a great first step on the road to fitness if you’ve never trained or are coming back from a long lay-off. If, however, you don’t regularly push your limits in your sessions, your progress will soon stall. ‘If you want to jump-start your cardio fitness, intervals give you more bang for your buck than any other form of training,’ says running coach Martin Yelling (yellingperformance.com).
Formalised by German coach Woldemar Gerschler in the 1930s, interval training is a method of exercise that uses alternating periods of work and rest. The idea is that intense exertion followed by rest reaps more fitness rewards than sustained gentle exercise. Studies have shown interval training is better at boosting stamina, developing VO2 max and even burning fat than longer sessions at a consistent, lower intensity.
‘Intervals can be applied to any kind of cardio training, but the session needs to be structured,’ says Joe Turner from personal trainer academy the Training Room (thetrainingroom.com). ‘Decide how long each period will be, how hard your intense periods will be, how many intervals you’ll do and how much recovery you'll have.’
‘The balance of effort and recovery needs to be just right,’ says Yelling. ‘This will be different depending on your fitness level and what you want to achieve. For example, to develop top-end running speed you need to run faster for less duration with longer recovery. For endurance, you need to run at a lower intensity for longer with less recovery.’
Consistency is important. ‘It’s no good going hard on the first few intense periods, then being too tired for the remaining ones,’ says Turner. ‘Start off conservatively and slowly increase the intensity once you can complete each session.’
Intervals aren’t easy, but that’s the point. The almost immediate fitness gains you make – and keep making – mean they’re worth the effort and are far more effective than slow plods that only serve to wear out your trainers. These benefits include an increased metabolism, the stimulation of natural production of the human growth hormone (HGH) by up to 450%, and even the slowing of the ageing process.
A recent study carried out at Bowling Green State University, the University of Alabama and the University of South Carolina revealed that HIIT is optimised at a 2:1 work-to-rest ratio of training at your optimal speed for a minute, with 30 seconds of rest in between the next one-minute burst. Over a ten-minute period this would bring about better results than endurance training, according to the American College of Sports Medicine. Indeed, their study shows that two weeks of HIIT would amount to the same as between six to eight weeks of traditional endurance workouts.
Provided it is done intensely and alongside weight training, the notion that this method of exercise scuppers muscle gain has been disproved. That muscle is retained at the expense of weight marks a major feather in the cap of this highly versatile form of workout. Its flexibility is premised on the general rule being followed: train at maximum effort for a short period of time, recover and repeat.