Creatine, Caffeine And Fuel Use!

I received a number of questions about some types of creatine recently; even though we know it works for most users (research shows about 75% of users see results), there are a number of other questions aside from “will it increase my bench.” I also included a study on nutrient oxidation since my mailbox has also been flooded with questions about getting in shape for summer.

Caffeine Is Ergogenic

After Supplementation Of Oral Creatine Monohydrate

Although a majority of studies have tested caffeine’s effects on endurance performance, some research protocols have also measured caffeine’s effects on short-term high-intensity exercise.

The purpose of the study was to determine if supplementation with creatine monohydrate would negate the known ergogenic effects of caffeine, as one previous study had demonstrated.

Fourteen male subjects were tested on four different occasions. A preliminary test was first utilized to obtain a VO2 max (maximal oxygen uptake).

Next, during the pretreatment period, all subjects were provided with creatine and underwent a loading regimen for 6-days (0.3 g/kg bodyweight taken at 4 regular intervals throughout the day) and completed a test at a running speed of 125% of their previously measured VO2 max.

Next, 12-24 hours after the completion of the creatine loading phase, subjects were provided with caffeine (5mg/kg) or placebo and completed the same abovementioned VO2 max test.

VO2 Max Calculator: Enter the total distance covered in meters in 12 minutes and then press the ‘Calculate’ button.

* 1600 meters = 1 mile
* 5280 feet = 1 mile
* 3 feet = 1 meter

The moral of the story is that this study demonstrated that acute ingestion of caffeine still has ergogenic benefits for short-term exercise regardless of previous creatine ingestion.

Resistance & Aerobic Exercise

Have Similar Effects On 24-h Nutrient Oxidation

The primary aim of this study was to compare the effects of aerobic vs. anaerobic training on energy expenditure (EE) and substrate oxidation. It has been discussed ad nauseam whether cardiovascular exercise or weight lifting is better for weight loss; however, much of the discussions have been based on anecdotal evidence rather than actual research.

This study tested 10 non-obese male subjects on four separate occasions using whole-room, indirect calorimetry. The first measurement was utilized to obtain a baseline EE.

Next, In Random Order, 3 More EE Measurements Were Completed Over A 4-Week Period:

  1. An aerobic-exercise test (stationary bike at 70% VO2 max)
  2. Resistance-exercise (4 sets of 10 different exercises at 70% of exercise-specific 1 RM)
  3. A non-exercise control day.

During the bike session, subjects exercised for 49 ± 2 minutes and expended 546 ± 16 kcal. The 60-minute circuit training lifting regimen resulted in a 448 ± 21 kcal EE. Both exercise regimens had similar effects on substrate oxidation (there were no differences in fat oxidation over 24 hours, but there was an increase in the amount of carbohydrates oxidized).

1 Rep Max Calculator

What I can infer from this and other similar studies is what reader in their right mind wants to lose their hard-earned lean body mass by only doing aerobics? Looking only at the results from this study, we can infer that if the primary goal with an exercise program is weight loss (with no regard to the composition of that loss) there is a greater EE during aerobic exercise than a circuit type anaerobic exercise program.

Granted, most of the research coming from this group of scientists is with overweight and obese subjects; therefore, and they did mention this, these results cannot be extrapolated to bodybuilding or powerlifting type routines, but is still useful if you have clients you train.

Creatine Supplementation

Influences Substrate Utilization At Rest

Researchers are finally starting to branch out with their hypotheses about creatine’s functions, instead of just trying to determine if creatine supplementation increases lean body mass- we’ve known that for years now. To my knowledge, this was the only study of its kind to measure how creatine supplementation effects substrate utilization at rest.

The authors of this study hypothesized that creatine supplementation would result in a downward shift from fat, the typical resting substrate utilization, to an increase in carbohydrate utilization.

Subjects have participated in a 12-week resistance training program and in a double-blind, crossover design, were given creatine (20g/4 days, followed by 2g/day for 17 days) or placebo in two separate trials.

Each trial was separated by a 4-week washout period, research has shown it takes about 30 days for creatine stores to return back to normal after supplementation and was then again given supplemental creatine or placebo.

Although the primary outcome of the study was to determine the effects of creatine on substrate utilization, what creatine study would be complete without measuring gains in strength?


So, just to completely cover the report, here’s my quick description. In creatine group vs. the placebo group, strength (measured by 1-RM bench press) increased, and no major differences in body composition were found.

As with the use of substrates, carbohydrate oxidation increased during creatine supplementation (since there was a trend towards a rise in the respiratory exchange ratio (RER); higher RER implies more carbs are “burned,” and lower RER indicates greater usage of fat).

The exact mechanism is unknown, so there is certainly a need for further studies. The authors concluded that these findings indicate individuals who can supplement with creatine due to the increase in RER may decrease their ability to lose weight.

So What Have We Learned Today?

  1. Caffeine intake may enhance performance, regardless of simultaneous creatine ingestion.
  2. Aerobic exercise will utilize more energy in a shorter amount of time than a circuit-training anaerobic regimen.
  3. Creatine supplementation may inhibit fat loss.

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