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Fasted Cardio

Bigtex

Bigtex

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Aug 14, 2012
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Doing cardio in a fasted state may not be such a good idea unless want to lose muscle. However, by taking casein before you train you can avoid the muscle loss and actually increase fatty acid oxidation during and after training.

Bradley T. Gieske, Richard A. Stecker, Charles R. Smith, Kyle E. Witherbee, Patrick S. Harty, Robert Wildman and Chad M. Kerksick. Metabolic impact of protein feeding prior to moderate-intensity treadmill exercise in a fasted state: a pilot study. Journal of the International Society of Sports Nutrition 2018 15:56
https://jissn.biomedcentral.com/articles/10.1186/s12970-018-0263-6


Abstract
Background

Augmenting fat oxidation is a primary goal of fitness enthusiasts and individuals desiring to improve their body composition. Performing aerobic exercise while fasted continues to be a popular strategy to achieve this outcome, yet little research has examined how nutritional manipulations influence energy expenditure and/or fat oxidation during and after exercise. Initial research has indicated that pre-exercise protein feeding may facilitate fat oxidation while minimizing protein degradation during exercise, but more research is needed to determine if the source of protein further influences such outcomes.

Methods
Eleven healthy, college-aged males (23.5 ± 2.1 years, 86.0 ± 15.6 kg, 184 ± 10.3 cm, 19.7 ± 4.4%fat) completed four testing sessions in a randomized, counter-balanced, crossover fashion after observing an 8–10 h fast. During each visit, baseline substrate oxidation and resting energy expenditure (REE) were assessed via indirect calorimetry. Participants ingested isovolumetric, solutions containing 25 g of whey protein isolate (WPI),25 g of casein protein (CAS),25 g of maltodextrin (MAL),or non-caloric control (CON). After 30 min, participants performed 30 min of treadmill exercise at 55–60% heart rate reserve. Substrate oxidation and energy expenditure were re-assessed during exercise and 15 min after exercise.

Results
Delta scores comparing the change in REE were normalized to body mass and a significant group x time interaction (p = 0.002) was found. Post-hoc comparisons indicated the within-group changes in REE following consumption of WPI (3.41 ± 1.63 kcal/kg) and CAS (3.39 ± 0.82 kcal/kg) were significantly greater (p < 0.05) than following consumption of MAL (1.57 ± 0.99 kcal/kg) and tended to be greater than the non-caloric control group (2.00 ± 1.91 kcal/kg, p = 0.055 vs. WPI and p = 0.061 vs. CAS). Respiratory exchange ratio following consumption of WPI and CAS significantly decreased during the post exercise period while no change was observed for the other groups. Fat oxidation during exercise was calculated and increased in all groups throughout exercise. CAS was found to oxidize significantly more fat (p < 0.05) than WPI during minutes 10–15 (CAS: 2.28 ± 0.38 g; WPI: 1.7 ± 0.60 g) and 25–30 (CAS: 3.03 ± 0.55 g; WPI: 2.24 ± 0.50 g) of the exercise bout.

Conclusions
Protein consumption before fasted moderate-intensity treadmill exercise significantly increased post-exercise energy expenditure compared to maltodextrin ingestion and tended to be greater than control. Post-exercise fat oxidation was improved following protein ingestion. Throughout exercise, fasting (control) did not yield more fat oxidation versus carbohydrate or protein, while casein protein allowed for more fat oxidation than whey. These results indicate rates of energy expenditure and fat oxidation can be modulated after CAS protein consumption prior to moderate-intensity cardiovascular exercise and that fasting did not lead to more fat oxidation during or after exercise.

From the Discussion
The purpose of this investigation was to compare the effects of consuming supplemental levels of whey and casein, as well as carbohydrate, 30 min prior to a moderate intensity bout of treadmill exercise in comparison to completing an identical bout of exercise in a fasted state. The findings from this study indicate that exercising while fasted did not appreciably impact energy expenditure or substrate utilization either during or after exercise. Pre-exercise casein protein supplementation significantly increased rates of post-exercise fat oxidation and energy expenditure while whey protein resulted in less total fat oxidized during the exercise bout compared to casein (Fig. 5 and Fig. 6).

Fig. 5
fig-5.jpg

Fig. 6
fig-6.jpg


Results from this preliminary investigation suggest that consumption of 25 g of whey protein isolate or 25 g of casein protein 30 min before moderate-intensity treadmill exercise while fasted significantly increased rates of post-exercise energy expenditure when compared to the pre-exercise consumption of 25 g of maltodextrin or a non-caloric control. While differences in RER during exercise were not observed during either fasted cardiovascular exercise or post-prandial exercise, significantly more fat was oxidized following ingestion of casein vs. whey protein compared at two time points. Additional research is needed with longer exercise durations, varying exercise intensities, and nutrients consumed to better determine the impact of these findings.
 
Mike_RN

Mike_RN

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Aug 13, 2013
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I’ve read studies where whey and WPI were more easily converted to glucose through gluconeogenesis than more complex proteins. So this makes sense that casein would be tougher to convert and therefore increase fat oxidation . I’d like to see Egg and animal flesh studied as well. I hate fasted anything so this is music to my ears.
 
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Bigtex

Bigtex

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I’ve read studies where whey and WPI were more easily converted to glucose through gluconeogenesis than more complex proteins. So this makes sense that casein would be tougher to convert and therefore increase fat oxidation . I’d like to see Egg and animal flesh studied as well. I hate fasted anything so this is music to my ears.

I am like you, I hate being hungry. I have a feeling casein showed such an improvement because it is a very slow digesting protein. Whey digests quickly and causes a rush of amino acids which in turn boosts protein synthesis much better. The more fat in a protein the longer it takes to digest and the higher the thermic effect of food is with digestion. Slow proteins are also known for preserving muscle mass better. I agree this study makes a lot of sense.

Thanks Rag, I will start putting more of these up.
 
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FlyingDragon

FlyingDragon

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How is this fasted cardio if protein is taken before the cardio?????
 
BovaJP

BovaJP

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@Bigtex the article is great, and thank you for that find. Very interesting for sure.
One thing that I have observed or my philosophy on cardio in relation to this article is that I think this all is details for perhaps the hardcore competitor. In relation to let's say a person that is just wanting to maintain a fit lifestyle or trying to lost a little fat, i think as long as they do the cardio, no matter what time of day/fasted or non fasted. But this is only my philosophy on this subject, based on no science whatsoever. That is why it is helpful for these articles. Thanks man!
 
Bigtex

Bigtex

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I agree, as a hard core competitor the only objective is to win. The slightest advantage could mean the difference between 1st place and losing. Someone who is involved in being physically fit these difference really mean little. Thanks for your comments and appreciation. I have quite a few studies I will start putting on this page.
 
Snachito1

Snachito1

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Jan 12, 2018
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If your doing fasted cardio, won't it be different if you or on Vitamin S as far as losing muscle while doing it fasted?
 
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Bigtex

Bigtex

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For most of us it probably doesn't matter at all. For someone that is competing at a high level that small, possibly statistically insignificant figure even when steroids are combined, might mean the difference between 1st and 2nd place.

If I was competing at that level and doing cardio 1st thing in the morning, I would do GH, take casein . SInce GH his its Cmax (peak) at about 4 hours I would do the GH (2iu) 30 minutes before training along with the casein. Maybe 5-6 hours later another 2iu of GH, and maybe another dose at about bed time.

Something also interesting to note is the effect of thermic effect of food on fatty acid oxidation during exercise. Because casein is considered a slow digesting protein, it takes much more energy to digest and assimilate it. This also raises your basal metabolism during training causing you to further oxidize fatty acids. Doing a HIIT type exercise while fasting, adding GH and casein would boost the metabolism for 24 hours post-exercise. Now something to remember when doing all of this, its one thing to oxidize fatty acids, but its another thing to use them as energy, If we don't use the fatty acid we oxidize through lipolysis, it is stored again as fat through lipogenesis. Thus, smaller doses of GH spread out during the day.

So here is my opinion with all of this.......if you are doing exercise 1st thing in the morning fasted and drug free, you are almost shooting yourself in the foot, If you are doing GH and increasing IGF-1 levels you are preventing cortisol from rising and stopping any loss of muscle. Adding casein to either method would also help prevent amino acids from going through gluconeogenesis thus losing muscle mass. In otherwords, if you are just a fitness enthusiast hone of this shit even matters. If you are a competitive BB, you might want to consider it all.
 
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