Exercise & weight loss part 3 - Cardiovascular exercises

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1 Exercise & weight loss part 3 - Cardiovascular exercises Dr James Tang, MBA, BDS, LDS RCS General Dental Practitioner, Level 3 Personal Trainer (REP registration no R ), Sports Nutritionist & Level 3 Sports Massage Therapist, with special interest in postural dysfunction and lower back problems Should you always do the same type of exercise? Running on a treadmill for about 45 minutes at a steady pace results in initial weight loss, but after a few weeks, the body adapts and becomes more efficient, so the same exercise requires less effort and weight loss reduces. However, you shouldn t exclusively rely on aerobic exercise. You could still lose substantial amounts of muscle tissue with aerobic exercise as these exercises do not act as sufficient stimuli to ensure muscle retention. So which exercise is best for losing weight? When it comes to weight loss, anything that builds muscle is a good thing, so resistance training should be part of your workout. This would also help to slow the process of sarcopenia, the loss of skeletal muscle mass due to ageing. Engaging in resistance training, or ideally, combining it with aerobic exercises, could help older adults to reduce their abdominal fat whilst increasing or preserving muscle mass. Extra muscle helps to burn more energy at rest, even if only to a small degree. This is called the resting metabolic rate of muscle or RMR. Extra muscle will also burn more fat in the active phase, the active metabolic rate, so having more muscle will definitely help to burn more energy and fat. A weight-training programme, however, may not burn as many calories as a cardiovascular workout, so it makes sense to increase your total caloric expenditure through some form of cardiovascular activities, such as high-intensity interval training. Furthermore, selecting the correct type of cardiovascular exercises can enhance your aerobic (muscular endurance) and 1

2 anaerobic base (strength and power), enabling you to perform your resistance training more effectively. Cardiovascular Session The cardiovascular session should follow on from the warm-up which can involve the same type of cardiovascular equipment. At the end of the warm-up, the heart rate should be at the level required for the main cardiovascular session. Ideal equipment for the warm-up cross trainers/rowing machines warm up the entire body (upper and lower limbs). These are much better than fitness machines, such as the treadmill, which primarily warm up the muscles of the lower limbs. The length of time spent warming up depends on the individual; for individuals who attend the gym regularly, the warm-up does not need to be too long. For an older person not used to exercise (deconditioned individuals), the warm-up needs to be longer up to 20 minutes. However, in general, a 5-minute warm-up is adequate. Warm-up: %MHR mins Warm-up increase the heart rate to 50% MHR in the first minute and maintain it at that rate for a further 4 minutes. Cardio training zones These zones relate to the heart-rate range in which certain benefits might be expected. They are not exact but are useful as a guide to cardiovascular training as the benefits relating to each zone are reasonably accurate. 2

3 These zones are based on a range of percentage maximum heart rate (MHR) which was previously estimated using the formula MHR = 220 minus age. However, this formula is so general and cannot represent each individual because this MHR is the same for everyone of the same age, irrespective of their levels of fitness. New method = The Karvonen Formula 220 age = MHR MHR RHR (Resting Heart Rate) = HRR (Heart Rate Reserve) HRR x 60% (assuming a 60% cardio training zone) + RHR = MHR (specific to that individual). For example: work out the HR training zone for a 40-year-old with a resting heart rate of 70 beats/min = (RHR) = 110 (HRR) (110 x 70%) + 70 (RHR) = 147. So, this is the HR to which the individual should be trained in order to achieve a 70% cardio training zone. Moderate Aerobic Zone 50 60% MHR This zone is mainly suitable for deconditioned individuals. Regular exercise in this zone will lead to slight improvements in cardiovascular functions. The goal is to sustain a minimum of 20 minutes before progressing to higher intensity levels. Weight-Management Zone 60 70% MHR Training within this range develops both endurance and aerobic capacity; more fat is burned at a higher rate than the previous zone and it is therefore effective for weight loss. The American College of Sports Medicine (ACSM) Guidelines suggest training for minutes at a frequency of 3 5 days per week. Clearly, a greater amount of energy will be expended at 70% of MHR compared to that expended at 60% for the same amount of time; this will affect the overall amount of fat used as fuel for the exercise. Aerobic Zone 70 80% MHR This is the fitness zone at moderate-to-vigorous intensity. This level is more appropriate for individuals who are used to exercising on a regular basis. Anaerobic Zone 80 90% MHR In this zone, the individual s anaerobic threshold is normally reached. The amount of fat utilised (in percentage terms) as the main source of energy in this zone is greatly reduced because intramuscular glycogen is the predominant source of fuel, although exercising within this zone may consume more calories overall. The by-product of anaerobic glycolysis is lactic acid and the greater the intensity, the greater the anaerobic contribution. To recap, 1g of these different food components produces the following energy values: 3

4 Carbohydrate 4kcal Fat 9kcal Protein 4kcal Alcohol 7kcal Please be aware that regardless of the exercise, all three energy systems contribute to the production of energy to some extent throughout the duration of the exercise. The amount of contribution, however, depends upon the intensity of the exercise. Therefore, one has to remember that even during high-intensity events, a good contribution from the aerobic system is required in addition to a contribution from the anaerobic system. Duration of Cardiovascular Training ACSM suggests a duration of minutes continuous or intermittent exercise, regardless of the training zone being used. Two types of intermittent training can be performed: fartlek and interval. Because of the highintensity levels associated with these types of training exercises, it is advisable to have adequate cardiovascular fitness before contemplating them. Fartlek this involves randomly alternating the intensity level and recovery period throughout the duration of the session. This is essentially a random form of interval training. Interval training this involves high-intensity exercise, even if only in short bursts, which may rev up the metabolism and get fat mobilised in the post-exercise period. Essentially, the more intense your cardiovascular workout, the greater the duration and the greater the frequency, the larger the number of calories expended. You can, however, only maintain peak intensity for a very short period of time (say 30 seconds to 1 minute), you must use intervals where you train at peak intensity for a short burst followed by moderate-pace cardio (active rest), and then start all over again. High-intensity cardio sessions help you to increase your metabolism and maintain an elevated metabolism for hours after you ve completed your workout. Consult your exercise professional to select the most appropriate type of interval training for you. There are different forms of interval training that are designed to target the different energy systems mentioned above. Going into great detail about this is beyond the scope of this article but the table below illustrates the various forms of interval training that are designed to target the different energy systems you wish to enhance. 4

5 Energy system to be targeted ATP CP (Creatine Phosphate) Time to fatigue Fuel used Predominant muscle fibre type % Maximum heart rate Work/rest ratio for intervals Number of intervals within the session ATP 3 seconds ATP Type 2b NA NA NA 10 Creatine Type 2a & Type 4 20 seconds Phosphate 2b Lactic Acid (good for enhancing lactic tolerance*) Aerobic (submaximal) seconds Long Glycogen Type 2a & Type % (depending on fitness level) Glycogen, fat & protein % 1:3 (1 minute of exercise:3 minutes of active rest) 1:3 Type 1 50%+ 1:1 *One of the by-products of anaerobic glycolysis is lactic acid. The body can normally remove and deal with low levels of lactic acid. However, as levels of lactic acid begin to increase, the body reaches a point at which it can no longer remove it from the working muscles quickly enough. This happens at a heart rate, and hence intensity, that is specific to each individual and is usually accompanied by a rapid rise in heart rate and a slowing of intensity. This point is known as the onset of blood lactate accumulation (OBLA). The correct type of interval training can increase the individual s lactate tolerance. Until recently, it was commonly believed that lactic acid was the major cause of fatigue during highintensity exercise. It has since been widely accepted that this is not the case, as it is the acid (H+) produced during glycolysis that is more likely to cause fatigue. In fact, lactate has been shown only to have beneficial effects as it actually decreases the level of hydrogen ions in the muscle and can also be converted to make glucose for energy production. Cool down After any exercise sessions, especially intense cardiovascular training, it is important to cool down to avoid blood pooling (the collection of blood in the lower limbs) and to help get blood back to the heart through the veins (with non-return valves). Cool down by contracting muscles which act as pumps to squeeze blood through the valves back to the heart (venous return). During exercise, your muscles aid the amount of blood returned to the heart by contracting with more force around the blood vessels. This causes the blood to easily resist the forces of gravity and return quickly to the heart for reoxygenation and recirculation. When you stop exercising quickly, the muscles are no longer contracting against your blood vessels gravity causes the blood to pool in the lower extremities. When this occurs, you may feel faint or dizzy or experience a loss of consciousness. spike heart rate up to 50% (CV Spike RPE5) in the first minute then gradually lower it in the next four minutes (RPE 1 2) CV Spike to remove waste products and lactic acid sending blood around to do just that. 5

6 Warm-up: %MHR 50 Cool-down 10 Summary We discussed earlier that in order to compensate for extra weight, the spine can become tilted and unevenly stressed. As a result, over time, the back may lose its proper support and an unnatural curvature of the spine may develop. In particular, pain and problems in the lower back may be aggravated by obesity. This occurs in people with extra weight in their stomachs because the excess weight pulls the pelvis forward and strains the lower back, creating lower back pain. Before beginning any weight loss programme, it is important to ensure that it is safe. It is advisable that the patient first meets with a health professional who will take account of any back problems or back pain the patient is experiencing and help to design an appropriate weight loss programme. Although all of the reasons why excess weight may cause or aggravate back pain are not known, it has been firmly established that a lack of exercise is a major cause, and conversely, a regular and sustained exercise programme will help to alleviate episodes of back pain and prevent (or minimise) future episodes. Movement and exercise are the only ways to foster blood flow which distributes nutrients into the disc space and soft tissues in and around the spine. This exchange of nutrients through exercise maintains the health of discs, muscles, ligaments and joints in the back. Put simply, obesity results when more calories are consumed than are burned by the body over a long period of time. Avoid consuming large, infrequent meals or lots of high GI meals as they will produce 6

7 large fluctuations in blood sugar and insulin, resulting in fat gain. High insulin levels stimulate the manufacture of cholesterol in the liver. If you have any questions, please do not hesitate to get in touch 7