Posted: February 11, 2005

Science of Sport: Can Supplements Make You Stronger And Faster?

By Owen Anderson, Ph. D. (copyright © 2003-2005)

Dietary-supplement producers have cleverly marketed dozens of different products which are said to boost muscular strength. Do any of these supplements actually work?

In an attempt to determine whether the majority of "strength-boosting" supplements pad the pocketbooks of supplement makers rather than the muscles of supplement takers, researchers Steven Nissen and Rick Sharp of Iowa State University recently carried out a "meta-analysis" of published scientific studies concerning dietary supplementation and changes in strength and lean body mass (1). The not-so-shocking result of the meta-analysis: Only two supplements - creatine and HMB (beta-hydroxy-beta-methylbutyrate) - were found to increase lean mass and muscular strength significantly.

To carry out the meta-analysis, Nissen and Sharp first compiled a list of supplements from the product lists of eight major dietary-supplement companies - and from a review of six magazines targeted at the athletic community, as well as five published scientific reviews on dietary supplements. 250 different supplements made the final list for analysis.

For each supplement on the list, the Iowa-State investigators carried out a thorough, PubMed examination of the scientific literature published between 1967 and 2001, using the search terms body composition, anthropometry, exercise, and human - combined with the word "supplement" and the actual name of the supplement (for example, "chromium"). Nissen and Sharp trimmed down the large, resulting list of studies by confining their analysis to clinical trials and by rejecting investigations which did not involve resistance exercise or which included individuals suffering from abnormal health conditions.

To be included in the meta-analysis, the published studies also had to meet the following criteria:

(1) Full-body resistance training had to be carried out at least two times a week.
(2) A placebo control had to be utilized.
(3) The study had to last for at least three weeks.
(4) The "investigation" could not be a thesis, abstract, round-table discussion, letter, or comment.
(5) No dietary restrictions which might compromise muscular growth could be imposed on the subjects.
(6) The supplement had to be ingested in an amount in excess of the daily requirement.
(7) The supplement had to be consumed orally on a daily basis.

Only 48 studies (out of the hundreds in the initial "trawl") met all the inclusion criteria, and just six supplements (creatine, HMB, chromium, DHEA, androstenedione, and protein) had been scrutinized in more than one high-quality study. Seven supplements had been examined in just one decent investigation; these supplements were not included in the final analysis because of the inability to conduct statistical analysis on the published data set (statistical analysis hinges on variation in data, and where there is just one data point there is no variation). Out of these seven non-included supplements, amino acids, androstenediol, boron, and bovine colostrum had positive results in their solitary studies; meanwhile, pyruvate, tribulus terrestris, and vanadyl sulfate all had negative results. However, none of these findings attained statistical significance in the original work (statistical analysis was possible in the original investigations because the data from many subjects - rather than from a single study - was being analyzed).

In contrast with this non-magnificent seven, creatine featured a whopping 18 studies which met the inclusion criteria, with most of these investigations published between 1997 and 2001. The creatine studies averaged eight weeks in duration, the average loading dose was 19 grams of creatine per day for five days, and the mean maintenance dose was seven grams each day. Overall, creatine supplementation resulted in a net gain in lean mass of .36% per week, compared with placebo. Of course, the placebo-takers were strength-training, too, so they had to add on some lean tissue as well, right? In fact, the placebo participants achieved a lean-mass gain of about .20% per week, while the creatine athletes prospered with .56% each week, producing the .36% (.56 minus .20) net gain for creatine over placebo. In case you are wondering, a .56% weekly advancement in lean tissue for a strength-training creatine supplementer who starts with 60 kg of lean tissue would result in a gain of around .34 kg of muscle per week, or about three-fourths of a pound every seven days.

Creatine did pretty well in terms of strength gains, too, chalking up a net gain of 1.09% per week (the actual numbers were 2.09% for creatine and about 1% for placebo). A 2.09-% weekly gain would mean that if you started an eight-week period of training with a max bench press of 60 kg (132 pounds), trained diligently and appropriately, and supplemented with creatine during the period (as outlined above), you'd be pressing well over 70 kg (154 pounds) after your eight weeks of work (naturally, your strength augmentation might be more or less than this, depending on your prior training status and your overall exercise program).

Nine studies involving HMB supplementation qualified for the meta-analysis; all of these studies involved the supplementation of three grams of HMB per day (the apparent "gold standard" for HMB intake). In these nine studies, the net increase in lean-mass gain for HMB was a statistically significant .28% per week (.49% for HMB vs. .21% for placebo), and the net increase in strength was 1.4% weekly (about 5% against 3.6% for placebo). A 5-percent weekly uptick in bench-press max strength would have you pressing - from a baseline of 60 kg - around 85 kg (187 pounds) in eight weeks.

The drumbeat for chromium as a strength-boosting supplement has been sounding strongly and wildly throughout much of the last 15 years or so, but the Nissen-Sharp meta-analysis of the 12 included chromium investigations detected just a small (and statistically non-significant) upswing in chromium-related lean mass of only .08% (yes, that's about one-twelfth of one percent) per week. The strength gain associated with chromium usage was also non-significant.

Three androstenedione investigations made the final cut, and two DHEA works were in there, too. However, both androstenedione and DHEA failed to significantly influence gains in lean mass or strength. Androstenedione supplementation was actually linked with a strength loss of .06% per week, although this wasn't significant.

Four studies involving protein supplementation made Sharp's final cut, but - perhaps surprisingly - none of the studies documented increases in lean mass or muscular strength associated with extra protein intake. The reason for this may simply be that most individuals routinely ingest adequate protein to meet their daily needs, even when they are engaged in regular strength training; the vast majority of individuals included in published strength-training studies follow European or North-American diets, both of which tend to be fairly high in protein. In effect, most general-protein supplementation may be superfluous. Nonetheless, protein-containing products are the most extensively used supplements in the strength-training market.

Creatine supplementation has been covered extensively in the pages of Running Research News; a quick search of the Running-Research-News archives (please view at http://www.rrnews.com/archive.htm) reveals 11 creatine stories published since January, 1993. In fact, RRN was the first popular publication to detail the benefits of creatine supplementation for athletes - and to reveal that a select group of Olympic medalists had secretly been taking creatine prior to the 1992 Olympic Games.

We have focused much less attention on HMB, however (just one article in November, 1996). So - what exactly is HMB, and how is it supposed to work in an athlete's muscles?

HMB is actually a metabolite of an important "branched-chain" amino acid called leucine. There are two other branched-chain aminos (isoleucine and valine); the branched chains have aroused considerable interest primarily because some research has shown that they may have a special capacity to boost protein synthesis and inhibit protein breakdown. Out of the three branched-chain amino acids, leucine has appeared to be the most potent, and some scientists have speculated that it is actually HMB (the leucine metabolite) which makes leucine look so powerful in various scientific efforts.

In fact, there is evidence that HMB-supplemented chickens grow faster, increase muscle size to a greater extent, and die less often, compared with placebo pullets (2). In addition, the effects of HMB supplementation have not been exactly sheepish in some of the studies carried out with lambs; lambs dosed with adequate levels of HMB improve "feed efficiency," compared with placebo black-sheep (feed efficiency is simply the percentage of ingested food which is actually used to increase body mass, a key variable for the sheep-industrial complex). As it turns out, placebo sheep in the HMB studies often turn out to be sore losers; lambs taking HMB have a greater-than-50-% lower incidence of "soremouth disease," a troubling disorder in lamb flocks. In soremouth disease, oral proteins break down at abnormally high rates, so it is suspected that HMB's special protein-conserving properties may be at work here.

At the risk of making you think that you are now reading The Iowa Farm Journal, we should also mention that pigs taking HMB on a regular basis gain more weight, lose more "backfat", and produce richer milk for their offspring, compared with razorbacks who stumble through life without HMB. HMB supplementation is also associated with higher "carcass quality grades" in castrated male cattle and lower mortality rates in young calves who are engaged in interstate travel.

With all due respect to our farm friends, however, they are not people (you heard it here first), and - most to the point - they are not athletes in training; they are simply organisms trying to live and grow normally without getting caught up in the rigors of strength or endurance training. And, this seems to be where one HMB "catch" comes in. Although HMB has looked pretty good in studies carried out with previously untrained people, the popular supplement has not been so pretty in research conducted with real-live athletes. For example, in an investigation carried out by outstanding supplement researcher Gary Slater and his colleagues at the Sports Science Division of the Singapore Sports Council, six weeks of HMB supplementation failed to boost strength or body composition in resistance-trained male athletes, compared with strength-trained athletes ingesting a placebo (3). In this study, in which both standard and time-release capsules of HMB were utilized (with the conventional dosage of three grams per day), HMB not only had no influence on strength and lean mass; it also failed to improve muscle protein turnover or ameliorate muscle damage (the exact things which HMB should theoretically be able to do).

In an excellent, double-blind, randomized study carried out with experienced athletes, Rich B. Kreider and investigators from the University of Memphis (Kreider is now at Baylor University) divided 40 experienced strength trainers who averaged about an hour of training per day into three groups; athletes in the three groups supplemented their diets for 28 days with a fortified, carbohydrate/protein powder containing either 0, 3, or 6 grams per day of HMB (4). In this investigation, HMB supplementation did manage to do two things: It increased both blood and urinary concentrations of HMB. Unfortunately, HMB had no effect at all on protein construction or destruction, lean mass, fat mass, percent body fat, or one-repetition-max strength (the one-repetition max is the maximum amount of weight which can be lifted one - and only one - time). It is interesting that the athletes in this study, who trained seriously on a nearly daily basis, are exactly the kinds of individuals who would be most interested in purchasing HMB. Kreider, by the way, is a renowned supplement researcher who has carried out excellent work documenting the ergogenic effects of creatine (as well as the safety of creatine supplementation).

Some very well-conducted animal research has also failed to detect any of HMB's alleged protein-conserving properties. In a study carried out in France, HMB had no positive effect on the protein quality of two-month-old, growing lambs, for example (5). In this investigation, feeding a high dose of HMB (four grams per kilogram of body weight) did lead to a significant upswing in levels of some plasma amino acids, but the HMB regimen had no effect on whole-body protein turnover - or on skeletal-muscle protein synthesis.

So, let's say that you are a runner and that you would like to strengthen your legs by carrying out around six weeks of general work, another six of running-specific sessions, six weeks of hills, and a further six weeks of - dare we suggest it - explosive training. Or, let's simply say that you are a runner with sub-optimal body composition, featuring just a bit too much fat in various places and perhaps not enough propulsive sinew in your lower limbs, and you would like to engage in whole-body strengthening, both for fatigue-resistance and aesthetic reasons. Would it make some sense to use a dietary supplement to nudge your rather reluctant body in the right direction, or will exercise alone do the trick? If so, which supplement would probably provide the biggest bang for the buck (we should actually say "bucks"; supplements certainly do not come home with us cheaply)?

The answer is that it would make sense to use a supplement, as long as that supplement happened to be creatine. The Nissen-Sharp meta-analysis revealed that creatine supplementation produced a net gain in strength of about 1% weekly, compared to walking down the lonely strength-training trail without any supplementation at all. While that might seem like a small effect, it could lead to substantial differences in strength over time between creatine and cold-turkeyism (you remember that old story about one plus one equals two, and so on).

True, there is no scientific evidence to support the idea that creatine supplementation directly boosts endurance-running performance. However, distance-running success hinges on running speed, running speed is a function of the amount of force applied to the ground by the legs, and creatine supplementation - combined with great, running-specific strength training - could magnify that propulsive force. The only caveat is that muscle storage of creatine is associated with simultaneous water storage, which would make an endurance runner a bit heavier than usual. We'll wait to see what future investigations reveal about creatine and endurance-running performance; once the studies begin popping up, we'll even carry out a meta-analysis to see what's really going on. As for HMB, there is not enough support right now for its use by serious athletes. In fact, if Nissen and Sharp had carried out a meta-analysis only with the HMB studies which focused on trained subjects, it is extremely unlikely that HMB would have been linked with positive changes in body composition or strength. ©

References

(1) "Effect of Dietary Supplements on Lean Mass and Strength Gains with Resistance Exercise: A Meta-Analysis," Journal of Applied Physiology, Vol. 94, pp. 651-659, 2003
(2) "HMB: What Worked with Chickens May Now Help Strength Trainers and Endurance Athletes," Running Research News, Vol. 12(9), pp. 1-4, 1996
(3) "Beta-Hydroxy-Beta-Methylbutyrate (HMB) Supplementation Does Not Affect Changes in Strength or Body Composition during Resistance Training in Trained Men," International Journal of Sports Nutrition and Exercise Metabolism, Vol. 11(3), pp. 384-396, 2001
(4) "Effects of Calcium Beta-Hydroxy-Beta-Methylbutyrate (HMB) Supplementation during Resistance Training on Markers of Catabolism, Body Composition, and Strength," International Journal of Sports Medicine, Vol. 20(8), pp. 503-509, 1999
(5) "The Effect of a High-Dose of 3-Hydroxy-3-Methylbutyrate on Protein Metabolism in Growing Lambs," British Journal of Nutrition, Vol. 77(6), pp. 885-896, 1997

To learn about Owen-Anderson's running camps in California, please send a note to Owen at owen@rrnews.com.

Copyright © 1998-2004 by Running Research News