Exercise Physiology on Obesity and Weight Loss Kenji Sudoh MD Medical Orthopaedics

What percentage of people are physically active in the United States?

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88% 66% 44% 22% 11%

Weight gain and weight loss: not rocket science

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Total Energy Consumed - Total Energy Expended = Total gain or loss.

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Total in – total out = +/-

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Stuff analogy

BMR and RMR

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J. Arthur Harris and Francis G. Benedict

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Basal Metabolic Rate (BMR). Daily energy expenditure for the functioning of vital organs at rest in a post absorptive state at a neutral temperature.

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Heart, lungs, nervous sys, kidneys, liver, intestine, sex organs, muscles, and skin.

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Measured by gas analysis through direct or indirect calorimetry.

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Resting Metabolic Rate (RMR) less restrictive parameters than BMR

BMR

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BMR= 60-70% of daily energy expenditure , – Liver 27% – Brain 19% – Heart 7% – Kidneys 10% – Skeletal muscle 18% – Other organs 19%

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Decreases with age and with decreased lean body mass.

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Can be estimated through various equations using age, sex, height, weight, or lean body mass. Spennewyn et al. discovered that 16 kcal/d per pound of lean body mass

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Estimating calorie needs per day

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Total in – total out = gain or loss

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Total Energy Expenditure= BMR(70%) + activity(20%) + post prandial thermogenisis(10%)

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BMR or RMR account for majority in most individuals – Activity can account for as low as 5% in sedentary – Can be up to 75% in highly trained endurance athletes

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www.caloriesperhour.com

Why lose Weight?

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Accumulation of abdominal and visceral fat are linked to the development of Metabolic syndrome and it’s disorders: – Hypertension – Insulin Resistance – Glucose intolerance – Diabetes Mellitus – Dyslipidemia

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As little as 5% wt. loss can show benefits

Exercise and weight loss

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Which is the best way to lose weight?

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Marathon training program Daily walks Weight lifting program Aerobics Exercise bicycle Running sprints Swimming

Diet alone

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Calorie restriction is effective for wt loss • Total in – total out = gain or loss

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Decrease Fat Free Mass up to 36% Decrease Resting Metabolic Rate (RMR) up to 30% Lead to increased adipose tissue after intervention ceases

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For lasting results, important to maintain Fat Free Mass and Metabolic Rate

Aerobic exercise

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Decrease Fat Mass RMR increase up to 48h after exercise Increase β-adrenergic receptor sensitivity on adipose tissue Cardiovascular benefits Improved fitness Improved quality of life

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Limited effect on Fat Free Mass Limits on calories expended with activity

“Fat burning zone” of aerobic exercise

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Low intensity exercise (50% of max HR) – 60% of calories burned are from fat stores High intensity exercise (75% of max HR) – 35% of calories burned are from fat stores

Low intensity

High intensity

kcal/min

4

7

Fat cal/min

2.4

2.45

kcal 30min

120

210

Fat cal 30min

72

73.5

% of fat cal burned

60%

35%

High Intensity Interval Training

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Repeated brief high intensity sprinting (90% VO2max) followed by low intensity exercise or rest. Wingate test: 30s intense cycling followed by 4 min recovery 4-6 times, 3 times a week Other protocols: 8sec sprint 12 sec low intensity for 20 min.

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Catecholamine response: epinepherine drive lipolysis assist in releasing fat from subcutaneous fat stores

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Increase Aerobic fitness (VO2max) Improvement of 7-13% short term (2-6wk) Up to 46% in long term program. (6mo.)

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Supresses appetite

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Decrease subcutaneous fat mass

HIIT

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Trapp et al 15 wk HIIT program 20 min 8s/12s 3x/wk

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10% reduction in subcutaneous fat 10% reduction in abdominal trunk fat 2% reduction in body mass 26% increase in VO2max 33% increase in insulin sensitivity

Combination of HIIT and Aerobic Exercise

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Mourier et al. 8 weeks 2 days/wk 45 min cycling @ 75% VO2 max 1 day/wk HIIT 25 min 2min/3min rest » 18% decrease in subcutaneous fat 48% decrease in abdominal fat 2% decrease in body mass 41% increase in VO2max 46% increase in insulin sensitivity

(HIIT alone) (10%) (10%) (2%) (26%) (33%)

Resistance Training

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Known as weight training

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Decrease Visceral fat and subcutaneous fat Increase RMR Increase FFM Decrease FM Improved insulin sensitivity Increase HDL Increase VO2 max (3-4%) up to 10 % with circuit training

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Increased strength allows for increased participation of aerobic exercise – Ades et al. After 12 week RET 38% improvement in submaximal walking time

RT Programs

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Minimum of 6-8 exercises focuses on major muscle groups Back, Chest, Legs, Shoulders, Abdominals, Low back 2-3 times a week Minimum of 1 set of 12-15 reps to near fatigue.

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1 hour 3 time a week 2 sets of 12 rep 1 ab, 6 upper body, 5 lower body 50% of 1RM building to 67% of 1RM

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3 times a week 2 ab, 7 upper body, 1 set of 15 reps 5 lower body, 2 sets of 15 reps 90% of 3RM

Comparison of Resistance training and Aerobic training •

Ross et al. 16 week program, 24 obese women

Diet and Aerobic exercise

Diet and Resistance training

Exercise protocol

5 x week 15-60 min Stationary bike Treadmill Stair stepper 50%-80% max HR

3 x week 1 set of 8-12 reps 6 upper body 2 lower body

Reduction in Body Wt

11.4%

11.7%

Reduction in SubQ fat

22.6%

22.6%

Reduction in Visceral fat 34.2%

30%

Differences

20% strength increase

14%VO2max increase

Structured exercise vs. Lifestyle modification

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Andersen et al. 40 obese women, BMI 32.9kg/m2 Diet + structured aerobic program Diet + lifestyle coaching

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Instructed on a low fat low calorie diet 1200kcal/day

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16wk program Follow up at 1 year

Diet + exercise

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16 weeks 3 x 45 min step aerobic classes/wk Intensity varied from 7-11 METS Estimated 450-500kcal expended per session

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At the end, Instructed on long term individualized program Video provided

Diet + lifestyle

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16 week session Structured course on lifestyle change and weight loss Activity and diet journal Advised to increase activity 30 min/day – Take stairs instead of elevator – Walk instead of drive short distances 3D accelerometers to estimate activity

Results Weight Loss

Diet + Lifestyle change

Diet + Structured Exercise

Total weight loss @ 16wk

7.9kg

8.3 kg

Total Weight loss @ 1yr

7.1kg

6.9kg

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