Have you been walking regularly and feel like you have hit a weight loss plateau? Has your doctor advised you to walk as a cardio exercise, but you just can’t find time to do a 60-minute routine daily?
Many of us have found ourselves unable to go out for walks on crowded city roads, or inclement weather has kept us indoors. Boredom is another common excuse.
The struggle is real, but the answer lies in walking itself — interval walking to be exact.
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What is interval walking?
High-intensity interval training (HIIT) is in vogue in fitness circles these days. Interval walking works on the same principle as HIIT — a short period of intense workout, followed by a period of recovery, either through rest or through a less intense activity. This cycle is repeated for anywhere between 20 and 45 minutes.
However, since HIIT is inherently intense, it may not suit everyone. For some, especially the aged or those carrying injuries or health conditions, performing jumping jacks, squat jumps or lunges (exercises in a typical HIIT routine) is not advisable. But almost everyone can perform brisk walking (at their own comfortable pace) as it does not put undue pressure on the joints or the heart. This idea forms the basis of interval walking, a low impact yet highly efficient workout.
How to do interval walking?
A typical routine starts with a minute or two of walking at a comfortable pace. This is followed by a 30-second to a minute of fast walking or power walking, and a 30 second to a minute of slow or regular walking, recovering before the next burst of intensive walking. This cycle is repeated for 20 to 45 minutes.
The duration of the fast and slow intervals can be varied depending on the comfort level, health status and fitness targets. Advanced interval walkers do up to three minutes of fast walking, interspersed with one to three minutes of slow walking.
Sachin Pal, a fitness consultant who runs Garage studio in New Delhi, employs a simple test to hit upon the right walking pace. “Slow walking should allow you to walk and talk — talk easily while you are at it,” says Pal. “On the other hand, while you are fast walking, you should still be able to talk, but it takes a bit more effort to do so.”
The endurance and speed can slowly be improved by increasing the speed and/or interval durations. With consistent training, the resting heart rate goes down over time, improving fitness. The key is to make sure the increments are gradual.
So, interval walking could also be used by people training to eventually start jogging or running. “A simpler protocol would be eight jogging/running intervals of approximately 30 seconds, interspersed with approximately 120 seconds of low-intensity walking,” says Dr C Raghu, cardiologist, Aster Prime Hospital, Hyderabad.
Hydration between workouts is important too. That would ensure the fluid, sugar and salt levels in the bloodstream do not go down. Hydration need not mean having sports drinks. Natural drinks such as lemon water and tender coconut water work best, says Pal.
The right pattern of walking is also something to be mindful of, says Pal. The heel should land first, and then the toe.
“The stepping distance (distance between one foot and another), and the speed should be little on the higher side than the regular ‘walk and talk’ speed for fat burning to occur,” says Pal. “When your step distance is longer, then your quadriceps muscles are more active and get more oxygenated.”
To time the walks, interval timers or HIIT timer apps on smartphones can be used. If walking on a timer feels overwhelming, laps of the fast and slow-paced walk can be performed over a measured distance. Interval walks can be done indoors too, so weather or pollution or busy roads are not deterrents here!
Health benefits of walking
“Regular exercise improves glycemic control and reduces cardiovascular risk and mortality in patients with type 2 diabetes,” according to a 2018 review paper published in the journal Current Diabetes Reviews. “Continuous moderate to high-intensity exercise has been recommended to manage type 2 diabetes; however, only approximately 30 per cent of diabetic patients achieve the recommended levels of physical activity.
“The reasons for not engaging in regular exercise vary; however, one of the common reasons is lack of time. Recently, the effectiveness of short-duration interval exercise such as high-intensity interval training and interval walking has been observed.”
Nagpur-based Dr Bishakha Swain (MD, general medicine) agrees with the research findings. “Any kind of workout, any walking or aerobic exercise which helps cut down your fat would increase your insulin sensitivity,” she says.
But is interval walking better than regular walking? The physiological changes it induces might be small, but the benefits are many.
“Even if interval walking workout might not bring about a significant change in insulin sensitivity as compared to regular walking, it most definitely would help with increased calorie burning, comparatively, for those aiming for a weight loss,” says Dr Swain. “Walking can decrease your systolic blood pressure by few units (mm Hg), which can help with hypertension too. Further, incidence of heart attacks may decrease with regular exercise and a healthy diet.”
Pal elaborates on the role the workout duration has in the rate of calorie burning — the “19-minute mark” in workouts, be it aerobic or anaerobic. “When a workout is continued beyond the 19-20 minutes, the ATP process goes faster, the body is more active and sweating, and starts burning calories and, eventually, fats,” says Pal. ATP (adenosine triphosphate) is a molecule that is the energy currency of the cells in our body. Sugars (or carbohydrates) in our diet are broken down into glucose and energy molecules or ATP, and this process is part of our digestive metabolism.
So, even if you could walk for, say, 30 minutes, and gradually take it up to 45 to 60 minutes, it could lead to a reduction in waist circumference. Additionally, “this kind of workout is a stress buster, and makes your metabolic rate go up too,” says Pal.
Interval walking can help you reap maximum benefits in a shorter time span than your regular or continuous walking. The idea is to get your heart rate up by walking faster, then give it time to recover comfortably before you go for another lap of intense walking. Interval walking is also a great way to make your routine walks more interesting. It would surprise and challenge your mind to cope with the new, alternative pattern of walking, and get you out of the rut, monotony and weight-loss plateau.
Who is it for?
Experts say teenagers, young adults, healthy to older people, and those with conditions such as diabetes, obesity, thyroid, hypertension or even mild heart ailments could practise interval walking, staying within their comfort levels.
“This form of activity is feasible and has a low risk for people with lifestyle-related diseases, obesity, sedentary lifestyle, old age or cardiac disorders when performed at their own individual intensity,” says Dr Raghu.
“An interval walking exercise program provides comparable and, in some cases, greater health and fitness benefits compared to a traditional continuous walking exercise program in middle aged men and women as well as in post-menopausal women,” according to a research paper by Shawn Farrokhi et al., published in 2017 in the journal Gait & Posture. “Interval walking exercise programs may also reduce attrition (people leaving mid-way) within the first 24 weeks of an exercise program, and increase compliance compared to a continuous walking program.
“Walking exercise durations of 30 minutes or greater may lead to undesirable knee joint loading in patients with knee osteoarthritis, while performing the same volume of exercise in multiple bouts as opposed to one continuous bout may be beneficial for limiting knee pain.”
However, caution should be exercised when people with comorbid conditions and advanced cardiorespiratory diseases attempt interval walking.
“There is no clear contraindication to physical activity except in sick and comorbid persons with advanced cardiorespiratory diseases,” says Dr Swain. “The extent of physical activity may differ according to age and comorbid illnesses. For instance, in a heart condition called hypertrophic cardiomyopathy, endurance sports are absolutely contraindicated [advised against]. Other diseases like heart failure, coronary artery disease [blockage in heart vessels] and arrythmias [heart rhythm disturbances] also call for restriction in physical activity.”
Dr Raghu also insists on caution for those with heart conditions. “The role of intense physical activity for heart patients is controversial and not recommended by all authorities,” he says. “But this remains an excellent preventive tool for those without and at risk for developing heart disease.”
Dr Mohit Sharma, a diabetologist and hypertension specialist based in Chandigarh, says nutrition is also an important factor that needs to be monitored. “Deficiency in vitamins and other nutrients can lead to injuries and other health complications,” he says, recommending that a person should consult a physiologist and undergo a health and fitness check-up, including a nutrient panel, before starting any new workout regime. He stresses the importance of listening to one’s body during workouts, including routine walks, and being mindful and attentive to avoid overexertion.
How much is too much?
“The efficiency of exercise is determined by oxygen consumption or VO2 max, which is a potent barometer for cardiovascular fitness and overall heart outcomes, including death,” says Dr Raghu. “The intensity of exercise has been traditionally classified as moderate and heavy intensity.”
There is a basic concept by which anyone can monitor their ideal heartrate while working out, ensuring they remain in the green zone.
“For the prevention of heart diseases, a moderate intensity physical activity of 150 minutes per week or 75 minutes of vigorous intensity is recommended,” says Dr Raghu. “The target VO2 max or heart rate for this form of exercise [interval walking] is 70-85 per cent. An individual can calculate the target heart rate by subtracting age from 220, and 85 per cent of this number is the target heart rate. For example, for a 50-year-old, 220-50=170 and 85 per cent of this number, 145, is the target heart rate. So let us assume this 50-year-old wishes to achieve 75 per cent of target heart rate: his heart rate goal while exercising would be 109 beats per minute.”
However, a doubt lingers: is there a safe limit when it comes to interval walking?
“The exercise limit is not an ideal number; instead, it should be bespoke (customised) for that individual,” says Dr Raghu. “Personalised exercise schedules to improve endurance and consistent adherence to exercise would in fact lead to fall in resting heart rate, which is good.”
He says strength training is mandatory before starting an ambitious interval walking plan, lest the plans could get topsy-turvy due to a physical injury.
“Elderly, obese and sedentary individuals are prone for musculoskeletal injuries if they directly hit a heavy intensity protocol,” says Dr Raghu. “Compared to moderate workouts, heavy-intensity physical activity showed superior outcomes. But as you can see, before starting a heavy-intensity physical activity, a certified professional’s supervision is important.”
