As mentioned earlier, guidelines recommend up to 150 minutes of regular/moderate physical activity or 75 minutes of vigorous/intense Exercise per week to achieve a holistic goal of Health and Fitness.
Why is Regular Physical Activity Important?
The important role played by regular physical activity came to light after a 1953 study, which demonstrated that bus conductors have a consistently lower risk of heart attack vs. the sedentary bus drivers (Morris et al, The Lancet, 1953). Fifty years later (in 2012), the same journal published data suggesting that mortality related to physical inactivity (5.3 million in 1 year) exceeded that related to smoking (5.1 million), leading to a campaign last year, titled “Sitting is the new Smoking”.
For hypertensives, regular Exercise is considered equivalent to 1 drug, suggesting that almost one-third of all patients could control their blood pressure (BP) without drugs. Considering c. 29% of India’s adult population suffers from high BP, this means literally millions of patients can be managed without medicines. Exercise reduces blood sugar by 20-40 mg/dl, or between 0.5-1 units of glycosylated haemoglobin (i.e. Hba1c or the 3-month average blood sugar). Furthermore, all-cause deaths and heart attack-related mortality demonstrate an incremental trend in relation to increased daily consumption of television, a frequent sedentary activity. Exercise can change all this.
The public health implication of exercise is huge. However, it is barely recognized. Think about it. If any new drug were shown to have similar efficacy, it would be the toast of International Media. But since it is just good old exercise, it is simply postponed for the pill.
Moderate activity for adults includes brisk walking, swimming, cycling, gardening, running household chores, dancing, walking a pet, playing games with children and carrying weights under 20 kg while walking. Vigorous activities are running/jogging, fast cycling or swimming, aerobic dancing, competitive sports or games and moving heavier weights (> 20 kg). Healthcare authorities believe that benefits will accrue even from low impact exercises such as brisk walking, which have a minimal potential for causing injury while improving the overall effort tolerance, blood pressure and sugar.
But How Can One Apply This on a Regular Basis Through Aerobic Exercise?
A fit adult can easily walk a kilometer in about 10-12 minutes, so 4-6 km is doable in 45 minutes to an hour. The minimum effective duration is at least 10 minutes a session. Is time really the issue then?
When done periodically (ideally 5-7 days a week, but minimum of 2 days a week), this should be enough to provide tangible health benefits, as noted above.
But that’s not to say that one can’t or should not do vigorous exercise: there is incremental benefit accrued up to about 750 minutes of exercise per week, or over 1.5 hours daily. Even more potent fitness and health benefits are gained from speed walking, dancing, aerobic dancing, playing games or moving weights; these have greater bang for the buck.
Walking or running on the treadmill or cross-trainer is favoured by many. Here one has the advantage of tracking burnt calories and the achieved heart rate, though accuracy of these devices can vary. Their monotonous nature as exercises can also create inertia after some time.
Keeping in mind the injury potential of regular long-term running (discussed earlier), walking may be a more suitable activity for adults, especially after 30 years of age. While habitual runners who have been running since childhood may consider continuing as they enter their 30s and 40s, people who begin an exercise program for the first time after 30 would be well advised to study the frequent injuries (foot, ankle, knee, back and neck) that they may face.
It is important to find the right shoes for the activity concerned, with the help of a coach or a podiatrist. Barefoot running or using shoes without any padding to mimic barefoot running is also in vogue.
The concept of target heart rate is also useful here. The maximum predicted heart rate (i.e. the number of heart beats per minute when the heart is working at its maximum) for an individual can be estimated by the simple formula of:
MPHR = 220 - age
For instance, a 40-year old has an MPHR of 180 approximately. The training effect is good at 70-85% of the MPHR, and this can be used to guide a newbie into the amount of stress needed to provide significant health benefits.
Older people over 60, especially those who are starting to exercise for the first time can start with smaller goals (aiming for a target heart rate around 120-130 beats per minute), before gradually moving to faster speeds and longer distances. They should aim for a session of at least 10 minutes at a time, while striving progressively for 20-60 minutes per session in the long run, and a total weekly exercise duration of 150-300 minutes for best results.
Cycling has become very popular of late. There are safe cycling tracks available in many cities, and several regular groups too. They make for social bonding opportunities, in addition to endurance and strength training with remarkable long-term benefits.
Swimming is one of the best exercises – injuries are rare (ear/nose/throat infections, if one is predisposed) and salutary improvements are seen in effort tolerance and weight loss. Perhaps, no other exercise comes close to it in terms of weight loss, especially if done in cool water, as the body needs to work twice as hard in cool water for the same output, so as to keep the body warm.
Younger and/or healthier people can manage by playing games such as badminton, football, cricket or table tennis. Apart from the social benefits, they are more effective in burning calories while being enjoyable activities. They also improve reflexes and build muscles, which are a big advantage especially as one ages.
In summary, regular Aerobic Exercise is an excellent investment, bringing improved BP, sugar, body weight and overall health, fitness and survival benefits, that is a must for all.
This is a recurring column published every Sunday under the title: A Guide to Exercise. Next week, we shall discuss the concept of resistance training and Anaerobic Exercise.
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