Saturday, 14 September 2013


Learning and Review: Cardiovascular Exercise

Cardiovascular Exercise: Cardio: Aerobic exercise which intends to improve the oxygen system.  The heart rate is maintained at at least 50% of its maximum level.

Some science facts:

Ways of burning glucose/sugar: 1. Aerobic (with oxygen) or 2. Anaerobic (without oxygen. leads to lactate) 

ATP: energy currency of muscle cells. 
It is produced in the mitochondria in cells ("the energy factory" of a cell). Mitochondria produce energy (ATP). Mitochondria is able to increase in size and number. Increased size and number leads to an increased availability of energy. Break down carbohydrate and fat for fuel.

Calorie = unit of energy.

Sources at rest: Fats 80–90%; carbohydrates 5–18% and protein 2–5%

Sources during exercise: muscle carbohydrate stores (glycogen), blood sugar, blood fatty acids, and intramuscular triacylglycerols (fat that is stored in muscle and fat tissues).

Factors: intensity and duration of exercise, the initial muscle glycogen levels, and supplementation with carbohydrates during exercise.

Light-Moderate use mainly glycogen, glucose and fat. 
Endurance sport relies on mainly Glycogen. 

Muscle growth (hypertrophy) occurs by satellite cells, providing there is sufficient amino acids available i.e. a positive nitrogen status by ingesting more protein than is lost. (amino acids --> protein synthesis: MUSCLE IS A PROTEIN). 

Steady State Cardio vs HIIT

Steady state/LISS:
-burn calories and increase fitness/endurance. 
-low- moderate: able to hold a conversation
-e.g. walking on treadmill, riding bike
-heart rate at >65% of its maximum ability. 
-Aerobic system. 
- The muscle fibres used are Slow Twitch: Contract slowly, but keep going for a long time. 
Slow twitch fibres are red; they rely on a rich supply of oxygenated blood as they use oxygen to produce energy for muscle contraction. (AEROBIC)
Cardiac output = Heart Rate Stroke Volume
i.e. The volume of blood pumped from the heart in one minute is the sum of the number of beats of the heart per minute and the volume of blood pumped by the heart in each contraction. This enables the oxygen demands of the exercising muscles to be met.
Aerobic fitness is largely determined by Stroke Volume (which in itself is largely determined by Pre-load- i.e. how much blood is inside the ventricle). 


-spike your heart rate (>85%)
-aim of burning fat and increasing your fitness. 
-Short sprint intervals are coupled with low-moderate intensity. (bursts of speed at your full maximum)
-Examples include alternating a sprint (for, say 15 seconds), with a slower paced walk/jog (for, say 60 seconds), doing burpees, weight lifting. 
-Anaerobic system: generates Lactate.  
- The muscle fibres used are Fast Twitch: 
Contract quickly, but rapidly get tired
Fast twitch fibres don't use oxygen to make energy, so they don't need such a rich blood supply (typically lighter in colour) (ANAEROBIC)

Calories burnt
  • 15minutes of steady state cardio reads more kcal burnt than if you had done 15minutes of HIIT (alternating 1m sprint with 1m walk, for example). 
  • LISS: burn calories at precise moment
  • However, HIIT training is known for its 'afterburn' i.e calories are burned not only at the moment that you are exercising, but also for hours after: 24 hours. This is due to an elevated EPOC, which is the oxygen consumption - and thus caloric expenditure- after an exercise session. This has been depicted in LaForgia, Withers& Gore study whereby EPOC has a greater increase in HIIT than in steady state cardio.
Problem with endurance training:
-Body adapts to physiological stresses: Typically, 30-60minutes 3-7x week of endurance training leads to long term adaptions such as increased thickness of heart muscle, to become more effective and efficient as a pump. 
Improved cardiovascular function leads to an increased VO2 Max. 

VO2 MAX: ability to consume, distribute and use oxygen as a means to provided energy. It is a predictor of exercise performance. Increased VO2 max leads to improved exercise performance.

Having to challenge the body after it adapts (as aerobic fitness increases)
  • increasing the duration of the exercise: PROBLEM: Now if you are already doing a 45 minute run, and you have to increase it to 60minutes --> boring or time consuming. 

A study by Wilson et al  showed a temporary boost in weight loss with steady state cardio, that was short-lived once the metabolism adjusted. The study also showed there was more muscle loss in steady state cardio than in HIIT. 
Another 8week study by Daussin et al showed HIIT produced physiological gains, such as an increase in VO2 Max (15% in HIIT, 9% in steady state cardio), and an overall increase in performance and health. This is supported by Helgerud et al. 

How to changing your metabolism
  1. increase muscle muss
  2. Increase muscle’s oxidative capacity (mitochondria: number and activity: produce ATP and burn fats)

Gibala et al: 
HIIT: increase in the number and size of mitochondria 
Burgomaster et al, MacDougall et al:
increase in oxidative enzymes within the mitochondria

In terms of Fat burning
Perry et al:
-increase in fat burning with HIIT in 6 weeks 
Talanian et al:
-also presented this finding but in a 2 week study. 

Horowitz & Klein:
-ncrease in fat burning with steady state cardiovascular exercise also. 

Remember: If you see a form of exercise as a chore, something you really hate the idea of doing, guess what... YOU WONT BE DOING IT FOR LONG.. you will resent it, and resent your workouts, and mentally that will hinder your progress. Do what you love and love what you do. Do what gets you pumped and rearing to go, and if that is a 30-45minute run then DO THAT and ENJOY IT and F anyone who judges. Whatever works for you will WORK and lead to results. LIFESTYLE CHANGE- not short term fixes.

Cardio: more fat burnt as fuel but this is short term. I.e. short term studies show that steady state cardio is best for fat burning.
HIIT: Due to the changes in the Mitochondria, HIIT is ultimately the best. i.e. Long term studies show HIIT has the best change in overall body fat composition.

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