Week 2 - Overweight and Obesity - Part 2.pdf
Transcript
WEEK 2: OVERWEIGHT AND OBESITY – PART 2 EHR522: EXERCISE FOR METABOLIC AND MENTAL HEALTH CONDITIONS Subject Coordinator: Tim Miller [email protected] 02 6338 4442 Clinical Exercise Physiology, 5th Edition - Chapter 9 DIAGNOSTIC TEST...
WEEK 2: OVERWEIGHT AND OBESITY – PART 2 EHR522: EXERCISE FOR METABOLIC AND MENTAL HEALTH CONDITIONS Subject Coordinator: Tim Miller [email protected] 02 6338 4442 Clinical Exercise Physiology, 5th Edition - Chapter 9 DIAGNOSTIC TESTING Laboratory testing (conducted by a GP) should screen for Diabetes (fasting BGL +/- OGTT) Lipid profile (total cholesterol, HDL, LDL +/- triglycerides) Clinical or subclinical hypothyroidism (thyroid-stimulating hormone (TSH) and free T4) Comprehensive chemistry profiles can screen for non-alcoholic fatty liver and renal disease ECG is rarely necessary except to evaluate specific cardiovascular problems such as elevated blood pressure and palpitations EXERCISE TESTING There are no specific obesity-related guidelines that provide recommendations for exercise testing ACSM – Routine exercise testing in the overweight and obese population is often not necessary, particularly for those beginning a low- to moderate-intensity exercise program. When an exercise test is performed in those who are overweight or obese, the purpose is typically to assess for the presence of coronary artery disease EXERCISE TESTING Exercise testing may also be performed to determine functional capacity and develop an exercise prescription based on heart rate Although walking is the preferred mode of exercise for testing, it is not always practical in those who are obese Seated devices such as upper body ergometers, stationary cycles or recumbent stepping machines offer excellent alternatives that allow patients to achieve maximal exercise effort in a non-weight- bearing mode Because of the potential for a low peak exercise capacity, a low-level protocol with small increments (eg. 0.5 – 1.0 MET) may be preferred EXERCISE TESTING There are no specific recommendations for assessing muscular strength, muscular endurance and range of motion. A normal sequence of testing can generally be followed EXERCISE TESTING TREATMENT Treatment goals need to consider both the medical benefits of modest (10%) weight loss and the patient’s expectations International guidelines recommend a 10% weight loss within 4 – 6 months and weight loss maintenance as an initial weight loss goal because this amount is associated with several health- related benefits Patients, on the other hand, commonly want to lose 35% of their weight to attain their dream weight Few commonly prescribed weight loss programs achieve average weight losses that match patients’ expectations DIET THERAPY To lower weight, energy balance must be negative and calorie reduction is the essential first step For normal adults, 22 kcal/kg is required daily to maintain weight A bell-shaped curve describes a variation in average energy expenditure of about 20%. Hence, some individuals will require 26 kcal/kg and others only 18 kcal/kg per day to maintain weight The lowest calorie level for weight maintenance is about 1,200 kcal daily, even for those at bed rest Exercise and activity levels affect maintenance calorie levels by 25% or more, depending on the degree of physical activity MEDICAL MANAGEMENT SUMMARY DIET THERAPY Typically a deficit of 7,700 kcal is needed to lose 1kg, so typically appropriate diets can yield about 0.5kg of weight loss per week Because of the high calorie content of fat (9 kcal per gram) compared with carbohydrate and protein (4 kcal per gram) and the heart health benefits for cholesterol lowering, most national guidelines (including Australia) recommend low-fat diets Recently, higher-protein and lower-carbohydrate diets have been favoured by patients because of greater weight losses and better satiety. Higher- protein diets tend to promote satiety; and lower- carbohydrate levels can promote greater fat utilisation (ketosis), which can boost the rate of weight loss DIET THERAPY – RAPID WEIGHT LOSS When rapid weight loss is critical, medically supervised very low-calorie diets ( 30 or with a BMI > 27 if they have obesity-related comorbidities In addition to the medications listed on the previous slide, Ozempic (Semaglutide) and Saxenda (Liraglutide) are relatively new injectable diabetes medications that can be used at higher doses for weight loss. They achieve modest weight loss in completers (~ 4-5% of baseline weight) in trials of up to one year SURGICAL THERAPY SURGICAL THERAPY The fastest-growing area of obesity treatment is surgical procedures to restrict the stomach or cause malabsorption of food, or both Newer laparoscopic techniques can cause patients to lose one third of their weight (>50% of their excess weight) within 18 months Research has confirmed improved mortality rates with weight loss surgery, however there are significant risks (up to 1% for death and 15% for morbidity) Importantly, patients undergoing bariatric surgery must commit to a lifelong program of restricted diet, lifestyle changes, vitamin supplementation and follow-up testing to ensure safety Surgery is typically restricted to those with a BMI ≥ 40 of those with a BMI ≥ 35 if they have obesity-related comorbid conditions EXERCISE PRESCRIPTION EXERCISE PRESCRIPTION Exercise for weight gain prevention The amount of exercise required is in the range of 150 – 200 minutes/week (1,200 – 2,000 kcal/week) Exercise alone for weight loss High amounts of total caloric expenditure, likely in the range of >3,000 kcal/week (225 – 420 minutes/week), are required to lose weight by exercise without a caloric intake reduction.There is a dose- response relationship between physical activity and the magnitude of weight loss achieved Exercise and caloric reduction for weight loss Along with caloric reduction, aerobic exercise increases the weekly rate of weight loss by approximately 1kg over caloric reduction alone Minimally, this requires 150 minutes/week but will vary based on the amount of caloric reduction Exercise for weight loss maintenance Regular exercise of 60 to 90 minutes on most days of the week is generally recommended for long-term weight loss maintenance CARDIORESPIRATORY EXERCISE Initially, exercise and physical activity should focus on cardiorespiratory (ie. aerobic) modes. The primary reason for this approach is that aerobic exercise is the only type linked to reductions in body mass Although resistance training may provide added benefits, particularly with respect to body composition, the caloric expenditure of resistance training is less than that of aerobic exercise because It is performed discontinuously A single training session incorporates less exercise time than an aerobic session does Resistance training is commonly performed only 2 to 3 days/week because it should not be done on consecutive days EXERCISE PRESCRIPTION SUMMARY EXERCISE FREQUENCY Behavioural changes in activity must be consistent and long lasting if the patient is to lose weight and maintain weight loss over the long term Some individuals will not be able to perform daily exercise, though most will be able to achieve this goal relatively quickly. Key factors are to minimise the duration and intensity initially to prevent excessive fatigue or muscle soreness (ie. DOMS) that may sabotage the patient’s willingness to return to exercise Altering the exercise mode between sessions may also help reduce the risk of injury or allow any mode- specific pain to subside EXERCISE INTENSITY The intensity of exercise must be adjusted so the patient can endure up to 60 minutes of activity each day For those who have never exercised previously, a moderate intensity in the range of 50 – 60% HRR is typically low enough for sustained exercise An intensity closer to 40% HRR may be required by some individuals, particularly those who have not exercised recently As an individual progresses, a goal of 60 – 80% HRR is adequate EXERCISE INTENSITY Some individuals who are obese are hypertensive and may be taking a beta blocker (ending in “lol”). This possibility must be considered if intensity is prescribed using heart rate. Typical RPE values of 11 – 15 (6 – 20 scale) may be substituted when assessing heart rate is not convenient Interval training is typically not part of an initial exercise routine, but some individuals who establish and tolerate a regular exercise and who are successful with weight loss may enjoy this form of training Consider risk stratification and co-morbid conditions EXERCISE DURATION For those with little or no previous recent exercise history, beginning with 20 to 30 minutes each day is appropriate Breaking this exercise time into two or three sessions per day of shorter duration (5 to 15 minutes) may be required for extremely deconditioned people The focus should be on duration before intensity An accumulation of time over several sessions in a day is as beneficial as one continuous work bout with respect to total caloric expenditure Individuals should be encouraged to increase the duration from 20 consecutive minutes/day to 60 minutes/day or more on every day of the week so they are expending >2,000 kcal/week Increased levels of incidental physical activity should also be encouraged RESISTANCE EXERCISE In general, the exercise prescription for obese people should include resistance intensity in the range of 60 – 80% of 1RM, performed for 8 to 12 reps and two sets (progressing to as many as four sets), with 2 to 3 minutes of rest after each bout This plan will allow the person to perform 6 to 10 exercises in a 30 to 40 minute session Resistance exercises can be performed maximally on 2 to 3 days/week, ideally without working the same muscle groups on consecutive days In general, target large muscle groups RANGE OF MOTION Obese patients have a reduced range of motion primarily due to an increased fat mass surrounding joints of the body, in conjunction with a lack of movement and routine stretching ROM may improve spontaneously with weight loss Normal flexibility routines are recommended as tolerated EXERCISE TRAINING – IMPORTANT CONSIDERATIONS EXERCISE TRAINING Low cardiorespiratory fitness adds to the risk of cardiovascular disease and mortality in overweight and obese people, including those with heart failure Ample evidence indicates that regular aerobic exercise training improves physical functioning, independent of weight loss, in those who are obese or overweight Exercise training is likely most important in the weight maintenance process of weight control Regular exercise training expending more than 2,000 kcal/week is a strong predictor of long-term weight loss maintenance EXERCISE TRAINING - CARDIORESPIRATORY EXERCISE With respect to balancing time required for implementation of weight loss methods, the focus of exercise training in the overweight or obese person should initially be on caloric expenditure, which is best achieved with aerobic-based training The expectations for cardiorespiratory exercise training regarding haemodynamic and other physiologic system adaptations are similar to those for people who are not obese or overweight EXERCISE TRAINING - CARDIORESPIRATORY EXERCISE Acute blood pressure declines following exercise, and accumulation of exercise over time, may chronically reduce blood pressure independent of weight loss Weight loss by any method will preferentially reduce visceral fat. However, there is evidence that aerobic, but not resistance, exercise will reduce visceral fat even if there is no weight loss EXERCISE TRAINING - CARDIORESPIRATORY EXERCISE Weight loss via caloric restriction not only affects fat tissue but can also lead to undesirable weight loss effects on the skeletal muscle, bones, heart, liver and kidneys These changes can have negative effects on muscle and bone strength, cardiorespiratory capacity (VO2 peak) and resting metabolic rate Regular aerobic exercise has been shown to protect against each of these potential effects EXERCISE TRAINING - RESISTANCE EXERCISE Resistance training is recommended for most weight loss programs, particularly for those individuals who desire to lose large amounts, because it may offset potential losses in lean mass This is despite the paucity of well-designed studies comparing the effects of aerobic, resistance, or combined aerobic and resistance training on fat mass and lean mass changes in obese individuals
