Final Review

What is Diabetes?

‘Diabetes Mellitus’: inability to maintain glucose and insulin levels in the body. Diabetes is a group of metabolic conditions characterized by a failure to sustain carbohydrate and lipid homeostasis due to disturbances in insulin function, leading to impaired glucose and fat metabolism.

Type 1 Diabetes

(Previously: Juvenile Onset Diabetes/ IDDM) INSULIN DEFICIENCY

Insulin deficiency due to pancreatic β-cell death results in decreased glucose uptake in the tissues and increased hepatic glucose output, as well as increased lipolysis in the adipose tissue.

Type 2 Diabetes

(Previously: Adult Onset Diabetes/ NIDDM) INSULIN RESISTANCE

Insulin resistance that results in decreased glucose uptake in the tissues and increased hepatic glucose output, as well as increased lipolysis in the adipose tissue. DOESN’T MEAN THEY ARE OVERWEIGHT

Type 1 diabetes risk factors

Immune mediated (Genetic)

Type 2 diabetes risk factors

• Hereditary (2x risk if parent has type 2 diabetes)

• Obesity (80% are overweight or obese at onset)

• Abdominal fat distribution

• Age (over 45)

• Sedentary lifestyle

• Hypertension

• Dyslipidemia (inability to regulate blood trigliceride (fat) levels)

Metabolic Syndrome

1. Diabetes

2. Hypertension

3. Obesity

4. Dyslipidemia

Mechanisms that cause Type 2 diabetes

Primary cause: impairments in insulin signaling in the tissue

• Insulin is present, but there is compensatory Hyperinsulinemia that eventually leads to β cell exhaustion and insulin deficiency (after many years )

• Gradual onset – usually a few years until first symptoms appear

• ~10% of world population have T2D (many are undiagnosed)Associated with obesity

• Prevalence rates are constantly on the rise

Mechanisms that cause Type 1 diabetes

• Primary cause: Immune system attacks the pancreas, causing β-cell death

• Complete insulin deficiency (within a few months)

• In fact, without exogenous insulin, the patient would die within a year

• Acute and fast onset – usually symptoms appear within a few weeks

• ~1% of world population have T1D (~10% of all diabetes cases)

• Prevalence rates are constantly on the rise

What is insulin resistance?

An impaired response of the body to insulin, resulting in elevated levels of glucose in the blood (a key component of type 2 diabetes and metabolic syndrome).

Insulin

Anabolic Hormone

• Secreted from pancreatic β cells (Islets of Langerhans) in response to increased blood glucose

• High sugar intake stimulates release; no food inhibits release

• Effects stomach, liver, skeletal muscle

Major Diabetes Complications

As a result of extended hyperglycemia (uncontrolled diabetes), damage to vessels, nerves, and other cells results in:

• Cardiovascular disease

• Hypertension

• Stroke

• Kidney disease

• Blindness

• Nerve damage

• Amputation

What are the three pillars of diabetes treatment?

Medication, Diet, Physical Activity (all play off on each other and affect one another)

Medications for Type 1 Diabetes

• Insulin

  • MDI (Multiple Daily Injections)

  • Insulin Pump

Hyperglycemia

• Blood glucose > 250 mg/dl

• Too little insulin

• Polydipsia, Polyuria, Weakness, Impaired Vision, Changes in Mood, ‘Acetone Breath’

• Catabolic process utilizing protein as an energy substrate

• Ketoacidosis (the body does not have enough insulin to use glucose (sugar) for energy)

• Might induce a diabetic coma

Hypoglycemia

• Blood glucose < 60 mg/dl

• Too much insulin

• Confusion, Weakness, Tremor, Cold Sweat, Impaired Vision, Unresponsiveness

• Neuroglucopenia (brain doesn’t have enough glucose)

• Might cause loss of consciousness and death

• Must consume sugar ASAP in order to increase blood glucose levels

Insulin stimulated glucose uptake

With no Insulin, can tissues uptake glucose?

YES

• Glut 1 – continuous low-level uptake

• Contraction-mediated Glut 4 Translocation (during skeletal muscle contraction)

Counter-regulatory Hormones:

• Epinephrine/Norepinephrine (fight or flight response) (mobilize glucose)

• Glucagon (mobilize glucose)

• Growth Hormone

• Cortisol

• Catabolic, so their primary function is to mobilize substrates

• ↑ Lipolysis and FFA output from adipose tissue

• ↑ Hepatic glucose output

• ↓ Glucose Uptake

What Happens During Exercise

In order to maintain blood glucose: insulin levels DECREASE while counter-regulatory hormone levels INCREASE 

Which are the main effectors in blood glucose regulation, and how do they change

during exercise? (Think about insulin vs. counter-regulatory hormones and how they

maintain blood glucose levels in exercise)

Main effectors:

• Insulin → lowers blood glucose.

• Counter-regulatory hormones: glucagon, epinephrine, cortisol, and growth hormone → raise blood glucose.

During exercise:

• Insulin ↓ → limits glucose uptake in non-active tissues.

• Glucagon, epinephrine, cortisol, GH ↑ → increase hepatic glucose output and promote fat use.

• Muscle glucose uptake ↑ via insulin-independent (contraction-mediated) pathways.

• ➜ Result: Blood glucose maintained despite increased

What are the primary factors that increase glucose uptake, and what is the primary transporter molecule that facilitates glucose uptake by the skeletal muscle?

Exercise increases glucose uptake in active muscles, as well as insulin sensitivity. (Exercise has an insulin-like effect. Muscle contraction DIRECTLY promotes glucose uptake (insulin is not necessary). Glut4 Transporters are responsible for facilitating glucose into the skeletal muscle.

Exercise Increases Insulin Sensitivity Effects

• Insulin-stimulated glucose uptake and glycogen synthesis were markedly increased post-exercise.

• Increased uptake in the absence of Insulin (up to 1h post-exercise).

• Increase uptake only in the presence of insulin (from 2h post exercise).

• This effect could last up to 72h post-exercise

• Primarily due to increased Glut 4 protein levels

How to prevent exercise-induced hypoglycemia?

• If blood glucose < 100 mg/dl – Elevated risk for hypoglycemia

• Ingest Carbs before exercising and postpone the exercise 15-30 min

• In order to prevent hypoglycemia

• Inject Insulin in a non-active site

• DO NOT EXERCISE 2 hrs after insulin injection

• Reduce insulin dose by 20-50% (up to 90% reduction if using an insulin pump)

Exercise Benefits – T2DM

• Improves glucose uptake – less glucose in blood (immediate effect)

• Increases insulin sensitivity (short-term effect)

• Weight/fat loss improves insulin sensitivity (long-term effect)

• Reduced CVD risk factors, chronic illnesses

• Stress reduction

Physical activity plays an important role in preventing and treating T2DM

Exercise Benefits – T1DM

• Increases insulin sensitivity (can use less insulin)

• Helps maintain a healthy weight

• Reduced CVD risk factors, chronic illnesses

• Stress reduction

• Improves overall quality of life

Physical activity presents quite a few challenges in the treatment of T1DM. However, the potential benefits of well-planned exercise outweigh them.

Study the graphs that show plasma glucose response to aerobic vs resistance exercise

• A massive increase in counter-regulatory hormones

• results in increased hepatic glucose output

• with rates that surpass glucose uptake by the skeletal muscle

• So...

• Blood glucose does not drop as it does during aerobic exercise

• and might actually even increase

ADA Recommendation for PA in Diabetes

• at least 150 min/wk of moderate aerobic activity.

• 3 days/week, with no more than 2 consecutive days without activity.

• Alternatively, at least 75 min/week of vigorous intensity

• 2–3 sessions/week of resistance exercise on nonconsecutive days.

• Additionally, decrease the amount of time spent in daily sedentary behavior. Prolonged sitting should be interrupted every 30 minutes

• Finally, Flexibility training and balance training are recommended 2–3 times/week for older adults with diabetes.

General Exercise Plan for Type 1 Diabetes

Aerobic Exercise

• Intensity:

  • 50-90% of HRR

  • RPE 11-16

• Frequency: 3-7 d/wk

• Duration:

  • 20-60min total

  • 5-10min – Warmup

  • 5-10min – Cool down

Resistance Exercise (initial)

• Intensity:

  • 40-50% 1RM

  • Max weight at 20-10 reps

• Frequency: 2-3 d/wk

• Duration:

  • 5-10min –Warmup

  • 1-3 exercises per muscle group

  • 1-3 sets per exercise

  • 15-8 reps

General Exercise Plan for Type 2 Diabetes

Aerobic Exercise

• Intensity:

  • 50-90% of HRR

  • RPE 11-16

• Frequency: 3-7 d/wk

• Duration:

  • 20-60min total

  • 5-10min – Warmup

  • 5-10min – Cool down

Resistance Exercise (initial)

• Intensity:

  • 40-50% 1RM

  • Max weight at 20-10 reps

• Frequency: 2-3 d/wk

• Duration:

  • 5-10min –Warmup

  • 1-3 exercises per muscle group

  • 1-3 sets per exercise

  • 15-8 reps

• Circuit type training is recommended

• Target large muscle groups

• Use compounded movements (multi-joint)

• Beware of Isometric exercises

BMI

Body Mass Index — weight / height²

• No distinction between overweight and overfat

• Body fatness and BMI are only weakly related

• Relationship differs in different groups

  • Old vs. YoungOld vs. Young

  • Men vs. WomenMen vs. Women

  • Weight trained vs.Weight trained vs. Non-weight trainedNon-weight trained

• BMI IS NOT A BODY COMPOSITION MEASURE

• A disadvantage is that it cannot distinguish between fat and muscle so a muscular person could be labeled as “obese”

Normal BMI

<25 kg/m²

Overweight BMI

25-29 kg/m²

Obese BMI

≥ 30 kg/m²

Fat mass (FM)

• The absolute amount of body fat

• Includes all extractable lipids from adipose and other tissues

Fat-free mass (FFM)

• Lipid-free chemicals and tissue

• Water, muscle, bone, connective tissue, organs

• Basically, everything else that is not fat.

Relative body fat percentage (%BF)

• FM expressed as a percentage of total body mass (TBM)

Indirect Assessment of Body Comp Measures – Densitometry-based

Densitometry: assess the density of the body

Density = Mass / Volume

Archimedes’ Principle: an object repels water in a direct relation to its density

MRI / DXA

break body into components of muscle, bone, and fat and estimate their volumes (know body mass, can estimate density)

• Indirect Measures – Densitometry based

Dual-Energy X-Ray Absorbptiometry

Theory

• Transmit photons (X-rays) at 2 different energy levels and get different attenuation levels by fat, lean tissue, and bone

What does it measure?

1. Bone mineral density

2. Fat

3. Fat-free soft tissue

3 Component Model

• Potentially more accurate b/c it accounts for individual differences in 3 components

• Accuracy ± 3%Accuracy ± 3

Magnetic Resonance Imaging

High Accuracy ~ 1%

Issues:

• ExpensiveExpensive

• Labor intensive

Skinfold Thickness

assess subcutaneous fat at various places

• Indirect Measures – Densitometry based

Bioelectrical Impedance

Predict comp from resistance to the flow of electrical current

• Indirect Measures – Densitometry-based

• Resistance to current flow reflects the properties of different tissues

• Tissues that contain a high level of water (blood, muscle) are highly conductive

• Fat, bone, and air-filled spaces are not.

• Easy to use, appears sophisticated

Overweight vs Obese

• When body weight exceeds the normal or standard weight for a particular person based on height and frame size.

• Both involve having an excessive amount of body fat

• Usually determined by BMI (Overweight: BMI >25, Obese: BMI >30)

What is the % of overweight and obese people in the USA?

Around 70% of US adults are overweight (BMI>25) and 33% are obese (BMI≥30)

Body Weight Regulation

Energy Balance = (Intake – Expenditure)

• If intake and expenditure are equal, then weight will remain stable

• If intake exceeds expenditure, then weight will increase

• If intake is less than expenditure, then weight will decrease

Expenditure

• RMR (60-75%)

• Activity - exercise, non-exercise activity (15-30%)

• Thermic effect of feeding – energy required for digestion (10%)

Measuring Energy Expenditure

Substrate + ADP + Oxygen (O2) = ATP + Carbon Dioxide (CO2) + Heat

1. Measure Directly = measure heat

2. Measure Indirectly = measure other metabolic by-products (O2 and CO2)

These measures only estimate energy from AEROBIC METABOLISM

Indirect Calorimetry: Measuring Gas Exchange

Respiratory Exchange Ratio (RER)

• Respiratory quotient (RQ) is the ratio of CO22 production to O2 consumption at the cell (VCO2/VO2)

• When measured using expired gases, this ratio is called the respiratory exchange ratio (RER)

RER provides an index of energy derived from fat and carbs

1. RER = 1.0: 100% of the energy is derived from carbohydrates

2. RER = 0.7: 100% of the energy is derived from fats

3. RER = 0.85: ~50% of energy from CHO and 50% from fats

Caloric Equivalent for Oxygen

• Caloric value per liter of O2 depends on the substrate being oxidized.

• Glucose ~ 5 kcal/l O2

• Fat ~ 4.6 kcal/l O2

• RER can be used to determine the kcals per liter of O2 consumed, which is termed the caloric equivalent for oxygen.

Resting Metabolic Rate (RMR)

• Rate at which the body expends energy at rest

• Usually measured as whole body oxygen consumption

Basal Metabolic Rate (BMR)

• The minimum energy required for essential physiological functions (varies between 1,200 and 2,400 kcal a day)

• Directly related to the amount of muscle in the body

Daily Energy Use

• 1,800 to over 3,000 kcal a day

• Higher than RMR b/c of the energy required to move

Factors Affecting RMR

Fat-Free Mass (FFM)

1. Muscle uses energy

2. More muscle = more energy use

Body surface area (different than mass)

• More area = grater heat loss

• More area = more energy required to maintain body temp

• More area = higher metabolic rate

Other Factors

• Body Temperature

• Stress

• Hormones

Calculating RMR – the Weir Equation

RMR (kcal/day) = 1440  (3.941 * VO2 (l/min) + 1.106 * VCO2(l/min)).

Energy Intake

• Carbohydrates & Proteins = 4kcal/g

• Fats = 9kcal/g

• Alcohol= 7kcal/g

Energy Expenditure

• Walking/Running= 1kcal/1km/1kg BW

• Cycling = 0.25 kcal/1km/1kg BW

• Swimming= 4 kcal/1km/1kg BW

What is Gait?

An acquired skill consisting of several movements

 Getting up from a seated position

 Propelling the body forward

 Maintaining balance

 Direction changes in response to a changing environment

 Stopping

Gait Cycle – A Stride

• Stance – 60%, Swing – 40%

• Heel strike—>forefoot contact—>heel lift—>toe off

Walking/Gait Muscles

1. Tibialis Anterior (deceleration muscle—on shin, absorbs force)

2. Gastrocnemius

3. Hamstrings

4. Quadriceps

5. Gluteus Medius (Helps stabilize—not sway)

What to Look For in Gait

• Difficulty rising from a chair (muscle weakness, balance problems)

• Balance - do they veer off course? (cerebellar dysfunction)

• Widened base - if base width approaches two feet, The likelihood of psychogenic gait disorder rises, unless the patient has morbid obesity or an obvious structural explanation

• Shuffling gait

• Postural sway

• Rate of walking - start off slowly and then speed up or general slowness (joint degenerative disease, weakness)

• Steppage gait -lifting the leg higher than normal when walking (peroneal nerve injury, fibular injury, multiple sclerosis)

Antalgic Gait

painful gait, a limp to avoid pain

Ataxic gait

An unsteady, uncoordinated walk, a wide base of support, is seen. normally due to cerebellar disease

Festinating Gait

short, accelerating steps are used to move forward, often seen in people with Parkinson's disease

Hemiplegic gait

involves flexion of the hip because of the inability to clear the toes from the floor at the ankle and circumduction at the hip—unable to lift toes—feet are always flat

Steppage gait

A weak anterior tibialis muscle causes foot drop, and you must lift your foot up high to clear your toes over the ground.—can lead to knee pain since it is taking all of the force

Trenelenurg gait

Weak hip and gluteal muscles causing leaning over sideways a bit while walking

spastic gait

increased muscle tone due to CNS impairments

What is a Normal Gait in Elderly?

 Slowed speed (< 5 km/h)

 slowed postural support responses

 shorter step length

 increased time in double limb support

 Strength declines in leg and posture muscles

 Declined aerobic capacity

 Posture changes (stooped posture – increased pressure on posterior muscles)

 Neuromuscular declines

Step Length

1. Count #of steps it takes to cover 5 meters

2. Calculate: 500cm/step# = Step length (cm).

3. Do it twice and take the average

Comfortable Walking Speed

1. Measure the time it takes to cover 10 meters

2. Calculate: 10m / time (sec) = Speed (m/sec)

3. Do it twice and take the average

4. To convert: m/sec * 3.6 = Km/hr

Daily Walking Distance

1. Measure daily step # (pedometer/ smart watch/ phone app)

2. Measure step length

3. Calculate: Daily step # * Step length (cm) = Daily walking distance (cm)

4. To convert: cm / 100,000 = Km

Aging of The Motor System (Neuromuscular changes)

 Decreased muscle mass & strength

 Decreased muscle function

 Decreased dexterity

 Increased falls

 Increased disability

Sarcopenia

Decreased Muscle Mass

• Decreased fiber size

• Decreased fiber number

• Large, weight-bearing muscles – more susceptible

• results in systemic decrease in strength, so Grip strength will correlate with other muscles

Fiber Type Changes with Aging

• Decreased Type 2 fiber number (fast twitch)

Aging of the skeletal system

 Decreased bone density (osteoporosis)

 Increased fracture risk

 Decreased elasticity of connective tissue

 Decreased ROM in the joints

 Increased tendon stiffness

 Increased risk of tendon injury

 Most of these changes are due to disuse

 Physical activity offers protection

Aging of the Neural System

 Decreased neuron numbers

»» Ischemia, neurotoxins and apoptosis

 Decreased reaction time

 Decreased neural signal speed

 Decreased coordination

 Decreased dexterity

 Reduced cognitive function

Greater strength loss

• Rarely used muscles

• Concentric contraction

• High contraction velocity

• Maximal strength

• Power activities

• Large angles in the joint

• Women

Moderate Strength loss

• Daily used muscles

• Isometric + Eccentric contraction

• Slow velocity

• Muscle endurance

• Small angles in the joint

• Men

Benefits of Resistance Training in Elderly

 Improved mobility

 Improved ability to perform ADL

 Prolongs the period of functional independence

 Lowers the risk of falling

 Improved Bone Density

 Improves metabolic health

Resistance Training in The Elderly

 Most have chronic conditions – physician consent

 Avoid the Valsalva maneuver

 Longer warm up and cool down

 Incorporate functional exercises

 Multijoint, large muscle group exercises

 Machines are preferred over free weights

»» Less skill is required

»» Greater support

»» More gradual resistance adjustment

Aging of The Aerobic System

 VO2max ↓ 5ml/kg/min per decade

 12-14 ml/kg/min – Functional Threshold

 HRmax ↓ 10 bpm per decade

 Vascular stiffness + atherosclerosis

 Weakened respiratory muscles

 Stiffness of the costal joints

Benefits of Aerobic Training in Elderly

 Attenuates VO2max decline

 Attenuates SV and CO decline

 Improved mobility

 Improved ability to perform ADL

 Lowers the risk of falling

 Improves metabolic health

Functional Tests

• sit to stand test

• timed get up and go

• functional reach test

• Berg balance test

• timed one-legged stance

• 6 min walk test

• grip strength test: 30 kg for Men and 20kg for Women