MI and HIIT exercise

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Burning high and low

Which is best for your body – quick and dirty or slow and steady? Charlotte Watts investigates.

Human beings are designed to do a wide range of motions, at differing intensities and paces. Much movement is necessitated by actions we need at particular moments throughout our day, like walking up the stairs or running for a bus, but our primal movement patterns evolved from varied movement and speed: walking upright for nomadic long distances, sprinting for the hunt, running away from predators, and building shelters and other life-saving activities.

Modern exercise programmes often look to replicate these features, but most of us simply don’t have the time to cover the full range required and so gravitate towards a regime that suits our own inclinations – moderate intensity for those who have less energy to spare and high intensity for those wanting more of a buzz or a fast track to a firmer body.

How hard and fast should you exercise? Should it be a hard or slow burn? This very question is under constant discussion in the fitness world, with some preferring the steady pace of moderate intensity training and others attracted to the rush of high-intensity training.

Exercise – fast or slow?
Moderate intensity training includes any steady-state training where your heart rate is raised but kept relatively constant for anywhere from 20 minutes upwards, building stamina and endurance. A regime of 15-20 minutes of moderate intensity exercises daily, often cited as a foundation for basic fitness, can include walking, doubles tennis, physical tasks like housework and gardening, jogging, swimming, weight training, cycling and yoga.
High intensity training raises your heart rate very quickly; one distinct characteristic of it is that you’re working so hard that you lose the ability to speak. This can involve any moderate activity but ramped up in intensity: running faster, cycling quickly or uphill, swimming continual laps, a singles tennis game or any other activity requiring that you train harder and faster. Although moderate-intensity activities are a kinder transition to body tissues, joints and the heart, one minute of high intensity exercise is said to offer the same results in half the time, a big draw for those who don’t like exercise or can’t seem to fit it in.

High Intensity Interval Training (HIIT) is a particular form of high intensity workout that has become popular recently as an especially quick route to weight loss and improved muscle tone. It involves performing high intensity exercises (eg. squats, star jumps, burpees) for about 50 seconds, followed by about 10 seconds of rest so that some five different exercises can be covered in just five minutes.

There’s no question that high intensity outperforms slow and steady when it comes to weight loss. High intensity has shown to lose more fat and weight (especially around the middle) than doing traditional aerobic exercise for hours on end (J Obes. 2011; doi: 10.1155/2011/868305) and this may be related to its benefits on glucose regulation (Obes Rev.: 2015; 942-61). Another study compared HIIT running and MI endurance running, showing the impact on cardiometabolic health was more favourable for HI (Dtsch Med Wochenschr.: 2015; 7-13). Gillen et al. (2014) have shown that as little as three 10 min sessions per week, with only 3 x 20s at high intensity, could have significant effects on muscle oxidative capacity and several markers of cardiometabolic health.

Nevertheless, when it comes to improving overall fitness, more intense does not mean better, even for young people. A 2015 study on fitness levels compared aerobic activity where we use oxygen in normal (if heightened) respiration and anaerobic where short, HI exercise from seconds up to around two minutes means training without oxygen (J Sports Sci Med. 2015; 747–755). Fifty-five 18-28 year old volunteers, who had previously been doing less than 2 hours exercising low-moderate exercise a week were compared in MI exercise in two groups; 20 mins of steady state moderate to vigorous exercise or 20 minutes MI interval training, resting between 13 sets of exercise. Another group was 4 minutes total of 20 seconds of 8 sets HI interval training. All had five minute warm-up and cool-down periods.

Substantially equivalent fitness gains were seen in all groups, but the shorter HI time was misleading, as those exercising at MI were fully recovered and ready to ‘return to normal life’ immediately after, whilst the HIIT participants were “still visibly distressed at the end and often required an extended period of time to recover to the point where they could again pursue normal activities.” After eight weeks of training, the HIIT participants were found to have enjoyed their training far less than those carrying out moderate intensity exercises – a key factor for maintaining any activity

Many studies show advantages of high intensity over moderate intensity, although it doesn’t necessarily improve overall fitness. What is agreed is that “it remains ‘unclear’ whether one type of exercise training regimen elicits a superior improvement in cardiorespiratory fitness relative to its counterpart.” (J Sports Sci Med.: 2014; 702-7). A 2011 meta-analysis of six randomised controlled trials of a total 153 participants (40 overweight/obesity, 19 with metabolic syndrome and 94 with heart disease) showed that HI is superior to MI in terms of improving exercise capacity, but that further high quality studies with larger sample size are required to confirm this finding in adults with cardiometabolic disorders (J Cardiopulm Rehabil: 2011; 378-85).

Charlene Hutsebaut, an experienced personal trainer who creates individually tailored programmes for clients, recommends that beginners don’t jump right into HIIT as they can get injured or their hearts may not be ready for them. She favours moderate intensity for many of her city-dwelling clients as most suffer from some level of stress and she is keen to avoid client burn-out, even lowering the intensity where needed.

“If someone is doing HIIT continually and is constantly fatigued, they need to change what they are doing,” says Charlotte. Not only is this regime tiring, but it can cause injuries, particularly for those driven by constant achievement, who may ignore their body’s warning signals and push even harder.

Even when not injurious, harder is not always better, when it comes to exercise; varying programmes can actually result in far better fitness. One study showed that adding just one HIIT session into a week with usual MI exercise (J Sports Sci Med.: 2014; 702-7) can have meaningful improvements in cardiorespiratory fitness and that this combination of training can be well-tolerated in previously inactive overweight/obese individuals.

The healthiest approach, according to Hutsebaut, is to combine medium and high intensity in what athletes call periodizing. As both have their merits and effects, a smart blend can create the most sustainable and effective training. The switch from slow to faster allows for the bodily repair that ultimately increases muscle mass and reduces the likelihood of injury (Strength & Conditioning Journal: 1999; 56).

Much injury is rooted in muscle held in stress patterns or from the inflammation caused by the stress response. Inflammation is a protective mechanism to bring immune factors that prevent bacterial infection and protect tissues and seal potential wounds in the damage that can occur during fight-or-flight. Even if this is simply a perceived, emotional ‘danger’, our bodies still elicit this survival response. Whether you’re an athlete or a total beginner, if you’re going through a period of stress, mixing up different training methods is even more important, to avoid the body burnout and fatigue that can come from overtraining.

The level of intensity for you depends on your fitness – if you’re out of practice, a moderate activity can hit high intensity for you pretty quickly. If your typical day’s journey is from bed to car to desk to car to sofa to bed, suddenly switching from this mode to a high intensity activity could be a real shock to the system.

Listening to your own body and trusting what you feel rather than mindlessly following instructions barked out at you to ‘go for it’ is a mindful skill to cultivate towards fitness. This is particularly important if you are mainly working out to videos, where you are simply told what to do, but the instructor cannot be there in the room to give you individual assessment, attention and modifications. By slowing down or doing fewer repetitions where appropriate, you will ultimately feel more benefit and be able keep up without injury or exhaustion.

25-Minute Medium Intensity Strength Training Routine – by Charlene Hutsebaut

This routine is designed for all-body toning and strengthening. For those happy to stay at medium intensity, this is a great sequence to return to if your fitness levels drop and you need to build up again.

If you are wanting to move towards HIIT, but have a sedentary lifestyle, this sequence is a good entry route. Many HIIT movements need a decent amount of strength and flexibility – these are best built up at medium intensity so your body can carry them out without strain or injury. If you’re pumped full of adrenaline during an HIIT session, it can be easy to overlook that you’re doing yourself harm until afterward.

Practising the following sequence about 4-5 times a week for 8-12 weeks, alongside other moderate intensity activities including daily walking (minimum 15 minutes) can build a base of fitness, so that after this first block of time you can try a block of HIIT to see how you respond.

If you are a beginner, aim to do this quick strength workout once or twice a week. If you are intermediate or advanced, go for up to four times a week, ensuring ythat ou have rest days or perform different physical activities between workouts. And do ensure that you warm up first walk, gently jog and march, or walk up and down stairs on the spot for five minutes.

It should take you around 25–30 minutes to complete this exercise series, depending on the number of sets you do. Beginners can begin with the lower number of repetitions and work up towards 12; if intermediate or advanced you can do the higher amount listed, but everyone should complete all sets. The weight used for each set should challenge but not exhaust you by the end of your sequence.

3 sets of 6–12 repetitions

Level 1: Start on your hands and knees, hands just wider than shoulder-width apart, hips over knees.
Level 2: Start on your hands and knees, hands just wider than shoulder-width apart. Form a long board position from your shoulders to knees (imagine a straight line from your shoulders through hips to knees).
Level 3: Start on hands and toes – keep the body straight like a board from the shoulders to the toes.

All levels:
Inhale to bring chest towards the floor or exercise mat, bending your elbows only to a 90-degree angle. Exhale back up, straightening your elbows.

Keep your abdominal muscles gently tight throughout, pulling your belly button towards your spine and shoulder blades floating flat on the back/rib cage, down towards the hips.
Lead with your chest, keeping your head and neck in line with your spine. The old school ‘take your nose to the floor’ can overstretch your neck.

First set: 6-12 press-ups at your chosen level.
If you can do 12 of a level, then try some repetitions of the next level up.
If you can do 12 of Level 3, then add more repetitions in a set.

Wall Squats with Bicep Curls
3 sets of 10–15 repetitions
Equipment: dumbbells or plastic water bottles. Use a weight level that challenges you without making muscles hurt (beginner – 1.5kg dumbbells or small, full water bottle, intermediate/advanced 3kg dumbbells and above – 750ml-1L full water bottles)

Start in the position shown against a wall.
Your legs will work isometrically (without movement) by keeping you in position.
Feet should be at least 30 cm from the wall, pelvis, mid-back and shoulder blades against the wall for support to lift up through the spine.
The only movement to occur is with the arms.
Inhale to ease the dumbbells down beside your legs.
Exhale, pull the dumbbells back up, bending your elbows to the start position.
To get the most efficient use of the arm muscles keep the elbows tucked in to the sides of your body throughout entire movement.
Keep your abdominal wall gently tight throughout without pushing your lower back into the wall.

Double Arm Rows
3 sets of 8–12
Equipment: dumbbells, food tins, kettlebells or bags of groceries.

Both knees bent, then bend from the waist to tip over so that your torso is at a 45-degree angle to the floor.
Engage abdominal and lower back muscles to work your core muscles with safety.
Begin with cans, dumbbells, kettlebells or bags full of groceries below your shoulders (1), arms hanging, inhale here, then exhale to pull both arms up at the same time, hands to touch the hips, elbows to a 90-degree angle (2). Inhale arms back to start position.

3 sets of 6–12 on each side
Equipment: dumbbells, tins or kettlebells.

From feet together, holding dumbbells, cans or kettlebells in hands, take a long step forward with one foot.
Keeping your torso upright, inhale to the position shown here, just where your knees feel comfortable. You will still achieve a good (joint safe) workout even if you only do a quarter or half of the position shown.
Stand up to the start position on an out-breath.
Complete 6–12 repetitions on one side, then switch to the other leg.
Keep abdominal muscles gently tight while moving, and torso upright.

The Bridge
3–6 held for 10 seconds each

Lay down, knees bent and feet hip-width apart and comfortably close to the buttocks – settle the lower back here for at least 10 breaths.
Inhale and lift the pelvis off the floor one vertebra at a time.
Push back from the base of the big toe, roll the thighs in, flatten the belly and lift the breastbone towards the chin.
Stay as long as you can lift your chest with easy breath.
Roll the spine down and rest until back muscles settle.

Oblique Abdominal Rollback
2 lots of 3 on each side

1                                                                                       2                                                                         3

Begin in the seated position (1).
Breathe in, staying centred. Breathe out, drop the sacrum (triangular bum bone) down to floor as you twist to the left, pulling your belly button and breastbone through your back to create strong belly support (2). Extend your left hand (3), following it with your eyes.
Breathe in back to the starting position (1).
Repeat the movement to the right.

Don’t simply spring up out of these exercises and leave in a flurry of stress. Spend a minute or two stretching your muscles and relaxing.

If you’re looking for more opportunities to do moderate intensity training, try yoga. To practice yoga with Charlotte, click here.

  1. Dora Phill

    Charlotte, This post is quite descriptive and helpful. Thanks a bundle for sharing it. High intensity can be this much helpful I did not know that. thanks to you now, I know, I will certainly be using this post as a guide. Thanks a bundle for keeping this valuable info at one place. 🙂

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