Energy Balance & Exercise Flashcards
Name some physiological processes which expend dietary energy:
- Cellular maintenance
- Thermoregulation
- Growth
- Reproduction
- Immunity
- locomotion
Describe:
negative energy balance
positive energy balance
- Negative energy balance: is when expenditure is more than intake - induces weight loss
- Positive energy balance: is when energy intake increases/expenditure decreases - induces weight gain
e.g.: seasonal changes, injury, retirement
Define:
RMR
DIT
TEE
- RMR - resting metabolic rate
- DIT - Diet induced thermogenesis, absolute changes, e.g.: cost of eating. Dictated by the amount of food consumed
- TEE - Thermic effect of exercise
There are 4.18 per kilo Cal- The RMR of an athlete is usually the same on a rest day, to an active day
How many calories are in 1 gram of:
- Carbohydrate
- Protein
- Fat
- Alcohol
- 4
- 4
- 4
- 7
Describe how energy is stored in the body:
- Difference in fat distribution in body
- Adipose tissue as fat energy stores, 10.5kg, 94,500 kcal
- Glycogen stores in skeletal muscle, 0.4kg, 1600kcal
- Protein in skeletal muscle(energy reserve) - AA metabolised for energy, 12kg, 48,000kcal
- Liver storage of glycogen, 0.1kg, 400kcal
- Blood glucose energy store 10g
Explain energy balance:
what is the equation for EB?
Energy balance: Dietary energy intake - total energy expenditure
* EB is an output from the body’s physiological systems
* EB = EI - TEE
Explain energy availability:
what is the equation for EA?
Energy Availability: Dietary energy intake - exercise energy expenditure
* EA is an INPUT to the body’s physiological systems
* Amount of energy left to carry out all the other physiological requirements, e.g.: produce hormones, bone cells, muscle protein synthesis
* EA = EI - EEE
What is LEA?
What are the 2 types of low energy availability? (LEA)
Describe them:
Low energy availability: LEA
* Inadequate energy to support the functions required to maintain optimal health and performance
- Adaptable LEA - exposure to a reduction in energy availability associated with benign effects, short-term experience
- Problematic LEA - persistent disruption of various body systems, causing maladaptive responses
How can chronic energy deficiency impact female athletes?
Research found that the chronic energy deficiency status of female athletes lead to functional hypothalamic menstrual disorders and low bone mineral density
What are the 3 distinct energy deficiencies in athletes?
- Obsessive eating disorder - clinically mentally ill
- Intentional and rational mismanaged efforts to reduce body size & fatness to qualify/succeed in athletic competition - including disordered eating behaviour like fasting, diet pills, diuretics
- Inadvertent failure to increase energy intake to compensate for energy expended in exercise
What are the EA recommendations?
- growth/carb loading >45kcal/kg lean body mass
- weight maintenance ~ 45kcal/kg lean body mass
- weight loss = 30-45kcal/kg body mass
- never <30kcal/kg lean body mass
this is where we will begin to see the shutting down of physiological systems
What are some causes of LEA?
- Compulsive eating disorders
- Intentional efforts to improve performance by reducing body weight and body fat
- Inadvertent failure to match energy intake to energy expenditure
1kg of fat mass = 7,700kcal
How does exercise impact energy intake in the short-term?
People don’t eat more than usual even though they expend more calories - leads to lower energy availability in the short-term
What can cause inadvertent energy deficiency?
provide and example:
- 8 lean men living in a lab eating ad-libitum
- Everyone exercise to burn 840kcal per day for 7days (90mins of cycling)
- EA is the same, causing a knock on effect on EE over the 7 days
- Other physiological systems begin to shut down, as there is less energy available to them, causing an increase in EB
How does canagliflozin reduce energy intake?
- Canagliflozin(causes a release of glucose in the urine) vs a placebo for 52weeks
- Altering one side of the EB equation will lead to alterations in the other side of the equation
How might we prove that the psychological effects of exercise could be stronger than the physiological ones?
People increase their energy intake in anticipation to EE, but not after the exercise session.
- The psychological effects of anticipation of exercise can be seen as more strong than the physiological effects of exercise
Describe RED-S as a consequence of low energy availability:
How does RED-S affect male and female athletes differently?
How is research on RED-S going to be altered in the future?
- RED-S is a syndrome that progresses over a long period of time, injury and illness susceptibility increases
○ Decreases energy metabolism
○ Decreases reproductive function
○ Reduced musculoskeletal health
○ Reduced glycogen synthesis & cardiovascular health
○ Impairment of GI function (bloating, pain, cramps) - RED-S in males is associated with low libido and fewer morning erections as a consequence of LEA
- Linked to oestrogen deficiency in women and reduces the rate of bone protein synthesis, leading to amenorrhoea(loss of periods)
- The next 5 yrs to work on actually identifying these symptoms in athletes
Provide an example of how an athlete can develop RED-S:
- e.g.: an endurance athlete reducing their EI, reduces their EA during training, impacting performance due to their desire to modify their size/composition
How does LEA impact type 1&2 immunity?
- Type 1 immunity: defences are mounted against intracellular pathogens like viruses
- Type 2 immunity: defences are mounted against extracellular pathogens like bacteria
How does exercise affect the hormones for hunger/satiety?
Appetite is comprised of two drives. Hunger, which urges us to begin eating
* stimulated by the orexigenic hormone ghrelin
* satiety, which leads us to stop eating, is stimulated by several anorexigenic hormones including peptide YY (PYY), glucagon-like peptide 1 (GLP-1), and pancreatic polypeptide (PP)
* Research showed that hunger scores and concentrations of ghrelin were no higher after exercise than after rest, but PP was significantly increased after exercise.
What are some reasons that athletes can unintentionally develop RED-S?
1) Lack of knowledge and safe regulation of body weight and composition, while maintaining health
2) Ignorance of suitability of a particular body type and potential negative effects on health
3) Inadequate skills to safely promote health and performance, whilst limiting the development of RED-S, EDs
