1. Fakultas Kedokteran Universitas Andalas
FISIOLOGI OLAHRAGA
Rahmatina B. Herman
Bagian Fisiologi
Fakultas Kedokteran Universitas Andalas

2. Introduction
No other normal stresses that nearly approach the extreme stresses of heavy exercise
If some of extremes of exercise were continued for even slightly prolonged periods, they might easily be lethal
Therefore, Sports Physiology, in the main, is a discussion of the ultimate limits to which most of the bodily mechanisms can be stressed
Comparison:
- Extremely high fever approaching the level of lethality, body metabolism increases to about 100%
- During marathon race, body metabolism increases to % above normal

3. Strength of Muscles in Exercise
Determined mainly by its size
Maximum contractile force: 3-4 kg/cm2 of muscle cross-sectional area
The holding strength is ± 40% greater than contractile strength

4. Power of Muscles in Exercise
- a measure of the total amount of work that the muscle performs in a unit of time:
- determined by:
> strength of muscle contraction
> distance of contraction
> number of times it contracts each minute
- measured in kg-m/ minute
- power of 1 kg-m/minute, that is a muscle
> that can lift 1 kg weight to a height of 1 m in 1 min, or
> that can move object laterally against a force of
1 kg for a distance of 1 m in 1 min

5. Endurance Final measures of muscle performance
The efficiency for translation of muscle power output into athletic performance is often much less during rapid activity than during less rapid but sustained activity
Depends on nutritive support for muscle, more than anything else on the amount of glycogen that has been stored in muscle before the period of exercise
A person on a high-carbohydrate diet stores far more glycogen in muscles than a person on mixed diet or high-fat diet → endurance is greatly enhanced by a high-carbohydrate diet

6. …..Endurance Type of Diet Glycogen stored Complete exhaustion
(gm/ kg muscles)
Complete exhaustion
(minutes)
High-carbohydrate 40
240
Mixed 20
120
High-fat 6 85

7. Muscle Metabolic System in Exercise
The same basic metabolic systems are present in muscle as in all other parts of body
However, the activities of 3 metabolic systems are exceedingly important in understanding the limits of physical activity:
1. Phosphagen system
2. Glycogen-lactic acid system (anaerobic)
3. Aerobic system
The amount of ATP present in the muscles, even in well-trained athlete , is sufficient to sustain maximal muscle power for only ± 3 seconds/ one half of a 50-m dash

8. …..Muscle Metabolic System in Exercise
Phosphocreatine
Creatine + PO3
ATP
Energy
For
Muscle
contraction
Glycogen
Lactic acid
ADP
Glucose
Fatty acid
Amino acids
AMP
+ O2
CO2 + H2O
+ Urea

9. …..Muscle Metabolic System in Exercise
M of ATP/ min
Time
Phosphagen system 4
8 – 10 sec
Glycogen-lactic acid system
2.5
1.3 – 1.6 min
Aerobic system 1
Unlimited time (as long as nutrients last)

10. Recovery of Metabolic System After Exercise
1. Repaid of oxygen debt: ± 11.5 L
Body normally contains ± 2 L of stored O2:
- 0.5 L in lungs
L dissolved in body fluids
- 1 L combined with Hb
- 0.3 L combined with myoglobin
In heavy exercise , almost all O2 is used
After exercise over, the stored oxygen must be replenished by breathing
± 9 L more to provide for reconstituting phosphagen and lactic acid system

11. ....Recovery of Metabolic System After Exercise
2. Recovery of muscle glycogen
Not a simple matter
Often requires days
- A high carbohydrate diet: full recovery in ± 2 days
- A high -fat/ high-protein diet: little recovery even after 5 days
- Important for athlete to have a high carbohydrate diet before a grueling athletic event
- not to participate in exhaustive exercise during the 48 hours preceding the event

12. Effect of Training on Muscles
Muscles that function under no load, even if they are exercised for hours on end, increase little in strength
Muscle that contract at > 50% maximal force of contraction will develop strength rapidly even if the contractions are performed only a few times each day
Experiments on muscle building: maximal muscle contractions performed in three sets 3 days a week give approximately optimal increase in muscle strength and without producing chronic muscle fatigue

13. Fast-twitch and Slow-twitch Muscle Fibers
- twice as large in diameter
- the enzymes that promote rapid release of energy are 2-3 times as active in fast-twitch as in slow- twitch
Slow-twitch:
- mainly organized for endurance especially for generation of aerobic energy
- contain more myoglobin
- the enzymes of aerobic metabolic system more active than fast-twitch
- the number of capillaries per mass of fibers is greater than in fast-twitch

14. Cardio-respiratory Function in Exercise
Oxygen consumption and total pulmonary ventilation increase ± 20-fold between the resting state and maximum intensity of exercise in the well-trained athlete
O2 diffusing capacity, that is the rate at which O2 can diffuse from alveoli into the blood: 3-fold increase
Respiration is stimulated mainly by neurogenic mechanisms
Venous return and COP ↑
Hypertrophy of myocardium

15. Effect of Training on VO2 Max
VO2 max is abbreviation for the rate of oxygen usage under maximal aerobic metabolism
Experiments:
- Athletic training for 7-13 weeks: VO2 max increased only ±10 %, and the frequency of training had little effect on the increase in VO2 max
- Marathon training: VO2 max increased > 10 %

16. Body Heat in Exercise
During endurance athletics, body temperature often rises to 40°C even under normal environmental conditions
With very hot and humid conditions or excess clothing, the body temperature can easily rise to 42°C → heat stroke → destructive to tissue cells, especially to brain cells:
- extreme weakness
- exhaustion
- headache, dizziness, nausea
- profuse sweating
- confusing, staggering gait, collapse, unconsciousness

17. Body Fluids in Exercise
5-10 pound weight loss has been recorded in athletes in a period of 1 hour during endurance athletic events under hot and humid conditions
Essentially results from loss of sweat
Loss of sweat to decrease body weight
- 3%: can significantly diminish performance
- 5-10% rapid decrease can often be serious, leading to muscle cramps, nausea and other effects
Therefore it is essential to replace fluid as it is lost including replacement of salt and potassium

18. Thank You