Physiology of Aging: The Challenge of the 50+ Adult
The 50+ adult faces many anatomical and physiological changes. These
changes will occur as we age but regular physical activity can greatly affect the degree in which they functionally affect you. It has well be documented that physical activity is as close as we have come to finding the fountain of youth.
The aging process is multi-dimensional and the result of;
Physiological Changes with Age
1. Loss of Muscle Mass, Strength & Endurance
– Loss of 3 kg (6.6lbs.) of muscle mass each decade after age 45 (male~ 5%, female~2.5%).
- Decrease number & size of muscle fibres. Replaced by connective tissue.
- Decrease number of motor units (primarily FT motor units)
- Loss > in lower extremities.
Loss due to;
- Decrease in Growth Hormone production
- Decrease in Physical activity (Primary reason)
2. Decrease in Joint Flexibility
– Decreases after the age of 30
3. Cardiovascular Function
1. Left Ventricle
– after age 25 increase in wall thickness by 30%.(maybe due in response to age related increase in systolic BP)
2. Max Heart Rate
– Decreases ~ 5-10bpm every 10 yrs.
-HR adaptation to & recovery from exercise slower with age
Formula to calculate maximum Heart Rate;
- HRmax = 207-(.7 x age)
- HRmax = 220-age (males) or 226-age (females)
3. Stoke Volume (SV)
– moderate decrease with age due to;
- Decrease in amount of blood flow in ventricle to be ejected.
- Increase in resistance when blood is forced out.
4. Cardiac Output (Q)
Q = SV x HR
– No major changes in Q at rest or submax exercise.
2. Blood Pressure
– Increase with age due to an increase rigidity of blood vessels.
3. Blood Flow
– Decrease ability to redirect blood flow from internal organs, skin & inactive regions to the working muscles. Therefore the efficiency of delivering oxygen to our working muscles is lower in moderate to heavy exercise.
4. Neuro Control of Heart & Blood Vessels
– With increase age the heart & blood vessels become less sensitive to neurologic stimulation.This results in;
- Decrease HRmax
- Longer adaptation to increase workload (increase O2Debt).
- Postural Hypo tension-BP does not respond well when moving from lying down to standing up. Therefore get dizzy, confused, weak, fainting.
5. Aorta & Arterial Tree
– Becomes thicker & less compliant with age.
6. Total Peripheral Resistance (Blood flow from smallest arteries into capillaries)
-increases ~ 1% /yr due to;
- Increase in rigidity of blood vessels
- Decrease vasodilation function (ability of blood vessels to expand from neurologic stimulation.
Summary – With age there is a decrease in maximum heart rate and an increase in blood pressure but generally the cardiovascular function in non-diseased older adults remains adequate for resting & light physical activity.
4. Pulmonary Function (exchange of O2 & CO2 in blood stream)
Lung Volume– doesn’t change with age.
Tidal Volume(TV)(amount of air inspired/expired during each breath)- no change.
Respiratory Rate – no change
Vital Capacity (VC)(Max air on inhalation/exhalation)-decrease 4-5% every 10 years due to the lungs & chest muscles become less elastic.
Amount of work required to perform mechanics of breathing (Ventilation- amount of air we breathe each minute)- increase 3-5% each year due to the lungs & chest muscles becoming less elastic.
Summary – all pulmonary systems work well under rest & sub-maximal conditions
5. Anaerobic Capacity
Decreases due to:
- Decrease in muscle mass (primarily FT muscle fibers)
- Decrease Blood flow inside the muscles therefore decrease of Latic Acid.
6. Work Capacity (VO2Max) (O2 exchange efficiency)
– Decrease ~1%/year and a big decrease in VO2Max between ages 65-75 & 75-85. This is due to a decrease in;
- Total body muscle mass
- Ability to redirect blood to the working muscles
- Ability of working muscles to use available O2 (less blood flow through the working muscles).
7. Balance, Coordination and Agility
These decrease due to;
- Decrease in number of motor units therefore decrease in fine motor control.
- Slowing down of CNS function.
- Biological breakdown in neural networks
Gait– becomes shorter with broader strides and decrease ankle movement. There is a longer period of time when both feet are in contact with ground (double support).
Slower initiation, coordination , reaction time & speed of movement
This is due to a Due to a decrease ability to organize movement into;
- Proper sequence.
- Proper amount of force
(The more complex the task- the slower the reaction time)
8. Body Composition
- Height– decrease after age 30.
- Wt- progressive increase to ~ age 60
- Body Mass Index – BMI= Kg/m2 Highest – for men between ages 45 & 50 and for females between ages 60 & 70
- Body Water Content– Normal is 60-65% of our body weight but this decreases to ~50% in the elderly.
- Body Fat -increase with age (70 yr old male-21%, female 39%)
- Bone development– bone loss after age 35 by 1%/yr.
- Skin- wrinkle formation results from a loss of circulation to deep layers of skin, the skin unable to reproduce its cells as quickly. As well, collagen and elastic components breakdown therefore skin appears thinner & less resilient with age.
9. Sensory, Mental & Emotional Ability
-decrease sensory (hearing & vision), physical and mental ability (intellectual impairment, loss of memory) requires a constant psychological readjustment by the older adult to maintain self esteem & emotional wellbeing/control.
10. Social Interaction
-decrease with age as the older adult becomes more physically dependent on others
-Malnutrition is common in the older adult. This is due to;
- Sensory changes & food fondness,
- Gastric-intestinal disorders,
- Lack of motivation to cook.
- Lack of ability/motivation to shop properly.
If you’d like more info please contact Mike.