2009 Studies & Research Blog

One of the added benefits of including exercise in your day is for many people it will help to suppress the appetite, making it easier to stick with your diet and lose weight.

Recently though, researchers wanted to assess how the timing of that meal would impact the effect on the appetite that was seen.

They had twelve men perform three different trials in random order.  The first situation was to just eat a single meal, the second was to exercise two hours after the meal was eaten, and the third situation was to exercise one hour before the meal was to be consumed.

In each situation, they exercised at a rate of 60% of their VO2 max for 50 minutes and the meal they ate had a composition of 70% fat, 26% carbohydrate, and 4% protein.

Hunger ratings and plasma concentrations were measured at baseline and at 1, 3, 5, and 7 hours after the meal had been eaten, while ghrelin and PYY (appetite hormone regulators) were assessed at baseline, 1, 3, 5, and 7 hours after the meal.

The study found that when exercise was performed 2 hours after meal consumption, the appetite suppressing benefits of the exercise was extended and when the subjects exercised before eating the meal, appetite was decreased while there was an increase in plasma ghrelin concentrations.  

There was no impact on leptin levels regardless of meal timing though.  

Thus, the take home message from this study is that exercising after eating one of your meals might help you decrease the appetite even further, making it easier to stick with your diet program.

Reference:
Bushnell, D. et al. (2009) Appetite regulation via exercise prior or subsequent to high-fat meal consumption.  School of Exercise and Nutritional Sciences, San Diego State University. Appetite. Feb;52(1):193-8.

Most of us know already that females cannot build nearly the same amount of muscle volume as males are able to build, nor can they build muscle as quickly.  This is due to the different hormonal profile in a male’s body in comparison with that of a male - primarily the difference in testosterone, growth hormone, and then the female sex hormones.

Typically females will build muscle at about half the rate a male will (given proper training and diet conditions are in place, of course), with males generally able to synthesize one pound of dry muscle mass a month and females about half a pound.

Recently though researchers looked into another difference between males and females, that of the sensation of fatigue when muscular contraction was taken place.

The study included 12 males and 15 females with no history of neuromuscular disorders.  They were to perform sustained static gripping, in which the demand was gradually increased over time.  They started out with 10 seconds of 20% maximal voluntary contraction, then 20 seconds for the values of 30, 40, 50, 60, and 70% max voluntary contraction.

The study demonstrated that the forces exerted during the demand values of 70-80% of maximal voluntary contraction were significantly lower in males than in females and that there was a gender difference between the subjective muscular fatigue sensation between the male and female subjects at the demand values of 40-60% max voluntary contraction.

Therefore, we can conclude from this study, that males may experience a greater sensation of fatigue at any given workload in comparison with females.

So, while males may have the advantage of being able to build more muscle quicker, females appear to have the advantage over feelings of fatigue during various muscular tension levels.

Reference:
Demura, S. et al. (2008) Gender difference in subjective muscle-fatigue sensation during sustained muscle force exertion. Tohoku J Med. Jul; 215(3): 287-94.

Many individuals partake in the practice of using an ice bath to help speed along the recovery process and improve performance.  

But research studies are now demonstrating that this may not actually be the best process to be utilizing.

Researchers out of the Institute of Sport and Exercise Science at the James Cook University studied the effects of cold water immersion on recovery from anaerobic cycling.  They had seventeen participates go through the testing process, which involved two different bouts of cycling exercise spread 2-6 days apart.

The test involved doing two 30-second maximal cycling efforts followed by a one hour recovery period consisting of 10 minutes of easy cycling as a cool-down followed by either plain resting, or a 15 minute cold water immersion, with water temperatures of 13-14 degrees Celsius.

After the study was completed, it was noted that peak power, total work and post-exercise blood lactate were significantly reduced after the cold water immersion test in comparison to those who just used passive rest.

In addition to this, the peak heart rate the athletes experienced was significantly lower after the cold water immersion in comparison to the control subjects.

These results can indicate then that while ice baths may help to cool the body down and potentially reduce inflammation, if you’re looking for performance enhancing benefits, you may want to stay away from using them.

Reference:
Crowe MJ. Et al. (2007)  Cold water recovery reduced anaerobic performance.  International Journal of Sports Medicine. Dec;28(12)994-8.

In a double blind placebo controlled study using  15 resistance trained men as subjects for four weeks.  This study measured changes in plasma nitrate/nitrate(NOx) which is the primary method to measure nitric oxide(NO) changes. After a 5 minute period of wearing a  blood pressure cuff, subject performed isometric contractions using a hangrip device for one minute.

Following the one minute of hangrip contractions, blood samples were collected immediately following and at 3 and 10 minutes post handgrip contractions. NOx values for GPLC where statistically higher than the placebo at 3 and 10 minute pot protocol. How much of an increase in NOx you ask, 16 and 17% increases at minutes 3 and 10.

The exact mechanism of action of how GPLC increases NO is not fully understood, but one theory has been suggested, is  that GPLC decreases the activation of NADPH oxidase, the enzyme that decreases NO bioavailability.  Additionally, it is believed that the PLC component increases endothelial nitric oxide synthase, the primary enzyme involved in NO production.

Bloomer RJ, Smith WA, Fisher-Wellman KH
Glycine propionyl-L-carnitine increases plasma nitrate/nitrite in resistance trained men
Journal of the International Society of Sports Nutrition 2007, 4:22 (3 December 2007)

By:Athletic Edge Nutrition

Growth hormone is one of the most talked about supplements among those who are really looking to pack on quality mass and are against going on steroids.  Many are curious as to whether using growth hormone might be their ticket to more muscle mass – muscle mass that they’re really struggling to put on naturally.

Because of the interest in this hormone, many researchers have set out to study the effects upon its body in a variety of different situations.

The objective of this particular study was to look at the effects of growth hormone on the metabolism, body composition, muscle mass, and strength levels of adults.

After looking at the treatment groups the researchers findings were that it appeared as though daily GH and IGF-1 treatments did slightly increase the nitrogen retention in the body in normal adults, but only for a short period of time of approximately one month.

After prolonged GH administration however, the body started showing resistance to the anabolic actions of GH, therefore making it less effective over time.    In comparing groups of individuals taking growth hormone against those that weren’t using it, it was doubtful that the nitrogen retention associated with daily GH treatment resulted in an increase in contractile protein, improved muscle function, strength and athletic performance, says the study author, K.E. Yarasheski.

He goes on to state that even in catabolic or GH-deficient populations, Growth Hormone treatment provides only modest increments in nitrogen retention, muscle size, strength, and exercise capacity.

So, to summarize the findings of this study, next time you’re tempted to start using growth hormone in hopes it’s going to completely transform your physique, you may want to think again.  

Growth hormone is going to have much larger effects on the body during the early ages when large amounts of physical growth are still taking place, but after that it’s not going to do a great deal in the way of muscle mass promotion.

Yarasheki, KE. (1994) Growth Hormone effects on metabolism, body composition, muscle mass, and strength. Exercise Sport Science Review. 22:285-312.

Research has repeatedly shown that whey protein hydrolysate(WPH) increases blood plasma concentrations of amino-acids,  both faster and to a greater extent than regular intact whey. But, we also know, that WPH has a different impact on hormone levels such as insulin.

A recent study measuring the blood plasma insulin response between a WHP, that was 30% hydrolyzed was compared to a whey protein isolate(WPH). Sixteen healthy males ingested 45g of either WPH or WPI.  What was found was the WPH brought about a 28% greater plasma insulin response than the WPI and the area under curve was 43% greater with the WPH compared to the WPI.

Research has shown only a small amount of insulin is needed to prime protein synthesis and increasing insulin above 10-15U/ml does not increase protein synthesis or decrease protein degradation to any further extent.  Another recently completed study Koopmen R, Beelen M,. et al showed hydrolyzed protein(PeptoPro) increased plasma insulin levels to 16.5 U/ml and showed that adding carbohydrates to it had no additional impact on muscle protein synthesis.

This makes sense, as it through spiking insulin that carbohydrates exert their anabolic and anticatabolic effects. But the hydrolyzed protein without carbohydrates, easily increased the maximum amount of insulin shown needed to prime protein synthesis.

Based off these two studies finding and others, it appears, that extensively hydrolyzed whey, in these two studies cases, hydrolyzed  30% or greater can be used post-workout, without carbohydrate to maximally stimulate net muscle protein synthesis.

Power O, Hallihan A, Jakeman P.
Amino Acids. 2008 Aug 5. [Epub ahead of print]
Human insulinotropic response to oral ingestion of native and hydrolysed whey protein.

Written by:ATHLETIC EDGE NUTRITION