Many supplements never even make it to the "research phase" as it is well-understood that there is no possible physiological mechanism. Others show promise on paper, but do not produce the desired results that individuals are looking for.
This week I'm going to cover a few recent studies about popular supplements - antioxidants and HMB - and their effects on muscle damage. Finally, the last study discussed is regarding green tea and its effects on endurance capacity and fat oxidation. It's time to cut through the hype and get to the science.
It is well established that exercise-specifically eccentric exercise-increases the production of something called reactive oxygen species (ROS).
ROS have been associated with muscular fatigue and muscular damage. Subsequently, it is theorized that having increased levels of antioxidants in the blood may attenuate this normal increase in ROS, thereby reducing muscle damage. If true, this could be of utmost importance. Athletes have rigorous training regimens and might not provide the necessary stimuli for recovery and repair.
Eighteen, nontrained women (19-31 years of age) participated in a double-blind, placebo controlled trial in which researchers provided participants an antioxidant supplement (400 IU of vitamin E, 1 gram vitamin C, and 90 g selenium per 3 tablets) or placebo. Subjects were asked to consume either supplement 3 times per day for 14 days prior to the protocol and for 2 days post-protocol.
The protocol consisted of 4 sets of 12 reps using non dominant arm elbow flexors (biceps) over a full range of motion to elicit greater muscle damage. Subjects were also instructed to take 5 seconds to complete the eccentric portion of the exercise to ensure adequate muscle damage.
The researchers then used a number of known plasma markers of muscle damage to determine what, if any, effects the antioxidant combination product provided.
As expected, the exercises did in fact elicit biomarkers of oxidative stress. The antioxidant therapy used in this study significantly reduced the normal rise in protein oxidation (one marker of oxidative stress) and had a modest, but significant effect on another biomarker as well.
Considering this was the first study to date in women, more research is clearly necessary. It is also important to note that these were untrained women; it would be interesting to see if the same results would be seen in trained individuals, who are more accustomed to exercise stressors.
The first line of defense should be foods that are high in antioxidants; fruits and vegetables are great sources of vitamins C and A, almonds and wheat germ are great sources of vitamin E, and fish and meat are great sources of selenium. In addition, recommending a complete multivitamin, though, that has sufficient doses of vitamins C, E, and selenium, among others, may actually be potentially helpful too.
There is some evidence in untrained individuals that HMB possesses some anti-catabolic properties (i.e., prevents muscle breakdown). Since research is still very limited on this supplement and there is some promise in certain populations, HMB was put to the test in a more unique population: highly trained competitive athletes.
The theory was that because this caliber of athlete often participates in high-volume, high-intensity training, if a product could enhance recovery and act as an anticatabolic agent, it would be very useful.
Twenty-six NCAA DIII football players from various field positions were involved in this single blind experiment. Players were randomly assigned to either 3 g HMB or placebo.
The researchers tested the players before and after 10 days of preseason training. Various blood measures were taken, including testosterone and cortisol levels (anabolic and catabolic hormones, respectively) and performance measures were completed too. Finally, questionnaires asking about intensity, soreness and fatigue were completed by the athletes.
Over the 10-day period, subjects participated in 19 practices and 3 resistance training sessions. There were no significant changes in levels of intensity, soreness, or fatigue. There were also no significant differences in the hormone levels measured between groups. In addition, there were no significant differences in any of the performance measurements completed.
This study does not support the use of HMB for its purported anticatabolic or improved strength gain claims.
The effects of green tea on endurance capacity, energy metabolism, and fat oxidation were studied over a 10-week period in mice. After feeding the mice green tea extract, swimming times were increased by 8-24% and the mice had higher rates of fat oxidation.
The mechanisms utilized by the researchers allowed them to determine that the increased effects in endurance performance and increased fat oxidation were mediated in part by something called epigallocatechin (EGCG), which is the primary catechin in green tea.
Although this small study was conducted in mice, these findings support previous work with similar outcomes.
What Has Been Learned This Week?
- A combination of vitamins C and E, along with selenium might help attenuate the normal muscular damage response to training.
- HMB is useless for trained individuals.
- Green tea shows serious promise for enhancing endurance performance and increasing endurance capacity. The study above is just one of many. Drinking several cups of green tea has numerous other health benefits; try that before supplementing with an extract.
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