A Little Health & Fitness Science – FAT OXIDATION
When we hit the gym, regardless of the level of intensity or reason for the workout, maximizing fat oxidation is what we’re aiming for, whether you know it or not. Fat oxidation in its simplest form, is the process of breaking down fatty acids. Fat oxidation is at its best when the process results in fatty acids not only being broken down, but also used as fuel. This happens when the fatty acids are transported into the mitochondria – the energy hub of body cells. ATP is the energy molecule primarily produced by this process. Intramuscular triglycerides (fat located in muscle fibers) generally supply the fatty acids used for fat oxidation for up to two hours of continuous exercise. However, individuals with higher fitness have a greater storage capacity for, and ability to metabolize intramuscular triglycerides. In essence, their bodies use energy more efficiently.
At a very low intensity (25% of a VO2max), fat oxidation contributes approximately 90% of energy expenditure. You would be able to carry on a conversation while you are exercising at this intensity, and be able to maintain it for hours if you really wanted to. Maximal fat oxidation varies due to sex and training status and occurs at the higher thresholds of steady state exercise between 60 and 65% VO2 max.
There are a number of training programs that maximize fat oxidation.
Low-Intensity Endurance Training
Low-intensity endurance training refers to cardio based exercise, such as walking, running, cycling, and swimming, performed at an intensity at 50% or less VO2max for 20 to 60 minutes. Low-intensity endurance training is particularly great for those who are traditionally inactive, have lower fitness levels, or who suffer from clinical limitations (i.e., arthritis, chronic pain). In a recent study, 8 weeks of low intensity cycling at 50% VO2max for one hour, done four times per week improved fat oxidation by approximately 30% in overweight and obese adults. These results show that low-intensity endurance training, one of the most accessible forms of exercise, increases the proportion of fat oxidation for energy production and overweight and obese adults. Again, this is what we want – breaking down fatty acids to be used as fuel (energy).
Moderate-Intensity Continuous Training
Moderate-intensity continuous training refers to continuous, cardio-based training performed at or near the threshold of maximal fat oxidation, approximately 60% VO2max. If you are using the talk test, moderate-intensity continuous training is training where most individuals can barely maintain a conversation during exercise. If you can only say a few words before needing to take a breath, you’re probably above the threshold…dial it back! Moderate intensity continuous training triples the amount of fatty acids in circulation and improves fatty acid transport into skeletal muscle mitochondria for oxidation. A 40-minute session of moderate intensity continuous training performed three times a week for 12 weeks resulted in a 10% increase in fat oxidation and a 12% increase in VO2max. This is a great outcome that shows not only improved fatty acid availability for energy metabolism, but also a near direct correlation between improved fitness and fat oxidation with moderate-intensity continuous training.
Low- and High-Volume Resistance Training
Resistance training has been largely encouraged to prevent the age-related loss of bone density as well as muscle mass and strength. New evidence shows that resistance training is also effective at burning fat. Four months of low volume resistance training (3 sets of 8 to 12 reps at 70% 1RM for 9 upper- and lower-body exercise) increases muscular strength by 41% and decreases body fat by 3%. Additionally, decreases in waist circumference, which is an indicator of abdominal obesity, occurred in the high-volume exercise group that completed six sets per exercise. Researchers concluded that the high-volume exercise group had greater energy expenditure from the increased workload, which may have had the added effect of reducing abdominal fat.Every training cycle and program we offer is resistance training based and intentionally developed to include low-intensity endurance training and moderate-intensity continuous training to maximize fat oxidation. They are scientifically based and proven to maximize your results, with a little bit of creativity mixed in to keep them fun and interesting. Check out our offerings and experience maximum results that these cycles and programs produce.