1. Muscular Fatigue Mechanisms
Dehydration
Muscular Fatigue Mechanisms

2. VCE Physical Education - Unit 3
Dehydration
Sweating causes;
A loss of salt, electrolytes and water.
This can cause;
Impaired coordination, decision making and endurance levels.
An impact on the cardiovascular system
A rise in body temperature
Levels of dehydration are affected by;
Duration and intensity of session
Environmental conditions and acclimatisation.
The individual physiological characteristics
Fluid intake
Athletes can become dehydrated due to;
Not having access to fluids during competition
Not tolerating drinking while exercising
Inability to match intake with loss of fluids
If dehydrated, athletes are more prone to; Cramp, heat stress and heat stroke, poor performances and increase the risk of injury.
VCE Physical Education - Unit 3

3. VCE Physical Education - Unit 3
Dehydration
Sweating is the body’s natural process for regulating body temperature during exercise.
As an athlete’s core temperature increases so does the rate of sweat production.
Sweat contains electrolytes, salts and water, and dehydration is the loss of this body fluid. Varying rates of sweat, work, fluid intake and individual physiological characteristics all contribute to the level of dehydration that may be experienced.
VCE Physical Education - Unit 3

4. VCE Physical Education - Unit 3
Dehydration
p.141
Signs of dehydration;
Mild to severe thirst
Rapid loss in weight (1 kg of weight lost = 1L of sweat lost).
Dry lips and tongue, confusion
Decreased urine volume
Dark urine
Increased breathing rate
Light headedness nausea and headache
Confusion, nausea, headache
faster breathing rate than normal,
Fluid loss can be prevented by;
Drinking water prior, during and after events.
Use sports drinks for extended activities
Use a fluid replacement routine
Avoid being dehydrated before sport
Written Report p.140
Case Study p.141
VCE Physical Education - Unit 3

5. Dehydration continued
Combination of dehydration and electrolyte loss can make the athlete more susceptible to cramp, heat stress and heat stroke.
A loss of 2% of body weight (just 1 kg for a 50-kg person) causes an increase in perceived effort and could reduce performance by %.
Loss exceeding 3-5% of body weight reduces aerobic exercise performance noticeably and impairs reaction time, judgment, concentration, cognitive abilities and decision making.
Complete hydration is vital for achieving optimal performance and minimising the negative effects of fatigue.
VCE Physical Education - Unit 3

6. Guidelines for Reducing Dehydration
Do not wait until you are thirsty - thirst is a poor indicator of hydration levels.
Drink cool water - absorbed more rapidly
Use a sports drink if exercise is 1 hour +.
Avoid starting exercise dehydrated.
500 mL of water mins prior to the game.
Drink at least 200 mL of water every 15mins during
Weighing yourself before and after sport is a good way to assess fluid levels.
One kilogram of weight lost = one litre of fluid lost.
After participating, aim to replace more than the fluid lost as sweating and fluid loss continues after exercise.
VCE Physical Education - Unit 3

7. VCE Physical Education - Unit 3
Web Links – Chapter 6
Nicholas Institute of Sports Medicine and Athletic Trauma – exercise physiology:
Information on skeletal muscles in the human body:
Sport science (site for sports research):
Anaerobic management (training and recovery):
Biophysical journal online:
PubMed (includes links to full text articles and other related resources):
Article – Unravelling the Process of Muscle Fatigue:
Physiology online magazine (American Physiological Society):
Science-a-go-go (science news, research and discussion):
University of Western Australia, physiology department:
Innovations Report – Forum for science, industry and business: report.com
Australian Sports Commission:
Find 30 promotion (Government of WA Department of Health):
Walking School Bus promotion (UK):
Ministry of Health (New Zealand) toolkits:
The 10,000 Steps Rockhampton project:
Travelsmart Australia:
World Health Organisation:
Heart Foundation Australia:
VicHealth (The Victorian Health Promotion Foundation):
Be Active promotion (Government of South Australia):
Go For Your Life:
Physical Activity Resources for Health Professionals – Introduction (Centre for disease control and prevention – USA):
Health Promotion (Public Health Agency of Canada):
Strategic Inter-Governmental Forum on Physical Activity and Health (SIGPAH):
Healthy youth (Centre for disease control and prevention (USA):
America On The Move promotion:
Papers from the International Journal of Behavioural Nutrition and Physical Activity:
Department of health and aging (Australian government):
Building a healthy, active Australia (Australian government):
National Public Health Partnership:
Sport and Recreation Australia:
VCE Physical Education - Unit 3

8. 22/09/2018