Creatine supplementation: what all athletes need to know

Creatine (methylguanidine-acetic acid) was discovered in 1832, but athletes have been taking it – in hopes of improving their performances – for only the last 10 years. Over that time period, a scientific consensus has emerged that creatine supplementation can indeed increase muscular strength and power and improve performances in relatively short-duration, high-intensity activities. The potential benefits of creatine supplementation for longer-duration, lower-intensity exertion (i. e., for endurance-type athletes) have, however, been hotly debated.

To get a better insight into this debate, you should understand that muscle cells use creatine to form creatine phosphate, a high-energy compound which can be used to rapidly synthesize ATP, the ‘energy currency’ utilized by all cells in the human body. Whenever a nerve cell fires, a muscle fibre contracts, or a kidney cell actively filters some urine, ATP ‘pays the bills’ (i. e., furnishes the energy needed to carry out the activity).

Creatine phosphate is also a ‘buffer’ which tempers the increase in intramuscular acidity associated with intense exercise; in this role, creatine might help allay the fatigue which can be caused by a drop in muscular pH. Because of these two key actions of creatine (ATP creator and buffer), athletes have become extremely interested in supplementing their diets with this unique compound.

There is no question that creatine supplemen-tation increases the amount of creatine phosphate within muscle cells, sometimes by up to 50 per cent. Research support for creatine has been strong, and PP readers will be aware of a lot of it. Studies going as far back as 1986 have shown that when creatine phosphate concentrations drop within muscle cells, those fibres are unable to exhibit normal force production. In addition, a variety of different scientific investigations have linked creatine supplementation with greater muscular force production and power, as well as higher sprinting speeds, faster cycling velocities, and quicker swimming movements during very high-intensity efforts. As a result, there are few elite power athletes in the world who have not given creatine supplementation a try.

But what about endurance athletes?
In contrast, there’s no question that creatine is less popular with the endurance crowd, compared to the power people (one of creatine’s side effects – weight gain – has helped to minimize its popularity among endurance competitors). Somewhat surprisingly, little creatine research has been carried out with endurance athletes, and the few investigations which have been completed have yielded inconsistent results.

Thus, more work has been needed, and in a relatively new study, researchers at Kingston University in Surrey and the University of Tasmania in Australia looked at the effects of creatine on 16 endurance kayakers who possessed a high level of fitness (VO2max = 67.1 ml/kg.min). All 16 subjects took part in an initial workout which consisted of three work intervals which were completed on a kayak ergometer and which lasted for a duration of 90, 150, and 300 seconds. The athletes completed each interval at the highest-possible intensity and recovered completely (heart rate back to resting level) between intervals (‘The Effects of Creatine Supplementation on High-Intensity Exercise Performance in Elite Performers,’ European Journal of Applied Physiology, vol. 78, pp. 236-240, 1998).

The subjects were then randomly assigned to either a ‘creatine group’ or a placebo group. Creatine-group members took four five-gram doses of creatine monohydrate per day for a total of five days, while placebo-group athletes ingested four five-gram supplements of glucose daily. After five days, both the creatine and glucose athletes repeated the three-interval, max-intensity workout.

There followed a four-week ‘washout period’, during which the subjects took neither the creatine nor the glucose supplements. Research has shown that four weeks is long enough to bring an elevated muscle creatine-phosphate concentration back to ‘normal’. Following the four-week washout, all subjects participated in the three-interval workout yet again. Following this re-test, the previous placebo subjects ingested creatine for five days (4 x 5 grams per day) while the former creatine athletes took the glucose placebo (this is what’s called a ‘crossover’ design). After five days, the athletes tried the three-interval session one last time.

Fatter – but stronger
In just five-days time, the creatine supplements made the athletes gain weight. Creatine supplementers gained on average two kilograms (4.4 pounds), or almost one pound per day during creatine supplementation. Meanwhile, the placebo-subjects’ weights held steady.

Creatine also increased the quality of the athletes’ efforts during the three-interval workouts. During the 90-second interval, the kayakers completed about 16 per cent more work when they had supplemented with creatine, compared to taking the placebo or being in the control condition (at the beginning of the study and after the washout period). During the 150-second interval, the athletes completed 14 per cent more work with creatine, and for the five-minute (300-second) interval the creatine subjects hit 7 per cent more work. Blood-lactate levels were also higher for creatine athletes after the 150- and 300-second intervals, compared to control and placebo subjects. However, this was not a bad thing; it merely reflects the fact that the creatine-supplemented athletes were able to work at a higher intensity (and thus ‘cough up’ a bit more lactate).

Note that the advantage associated with creatine supplementation became smaller as the duration of the work interval increased. This is not terribly surprising. As work-interval duration increases, the relative amount of the energy which is needed to complete the interval which is actually coming from creatine phosphate decreases, as the creation of ATP from the breakdown of carbohydrate (rather than from the transfer of a phosphate group from creatine phosphate) becomes much more important. As work-interval duration increases, exercise intensity also declines, which means that creatine phosphate’s role as a buffer becomes less important.

That doesn’t mean that the value of creatine supplements becomes negligible for the endurance athlete carrying out relatively long work intervals, however, because creatine supplementation did produce significant improvements in work output during the longest (five-minute) intervals utilized in this study. Thus, it is tempting to say that creatine supplementation would be very beneficial to endurance athletes during their training (150-second to five-minute intervals are commonly employed by endurance competitors).

Will it also be true for runners?
However, remember that the gains in this study associated with creatine supplementation were obtained by endurance kayakers, not runners. Endurance kayakers, of course, are seated during exercise, and therefore the gains in weight associated with taking creatine are not so troubling to them (the kayak and water – not the athletes’ working muscles – support most of the extra weight, and the only real drawback linked with weight gain is a slight uptick in drag, i. e., friction between the kayak and the water). The same is true for cyclists, but even one-pound gains can hurt the efficiency of runners; four-pound upswings will almost certainly slow them down.

What causes the gain in weight? Research indicates that most of the short-term weight gain associated with creatine supplementation is probably due to water retention. Eric Hultman and his outstanding team of researchers were able to show recently that as creatine storage by muscles increases, urinary volume tends to decline (‘Muscle Creatine Loading in Men,’ Journal of Applied Physiology, vol. 81, pp. 232-237, 1996). Over the long term, much of the weight gain associated with creatine could be produced by an actual increase in muscular mass, as the higher-quality workouts linked to creatine supplementation could lead to advances in muscle size, at least among athletes who are strength training with rather heavy resistances.

The answer is yes – but
Should endurance runners take creatine supplements? There is little doubt that creatine supplementation can improve the quality of endurance-runners’ workouts. Several years ago, scientists from England and Estonia asked five endurance runners at Tartu University in Estonia to supplement their diets with 30 grams (six five-gram doses per day) of creatine monohydrate per day for six consecutive days. During this six-day period, five other Estonian runners of comparable ability consumed a glucose placebo instead of creatine. All runners were unaware of the true compositions of their supplements (‘Creatine Propels British Athletes to Olympic Gold Medals: Is Creatine the One True Ergogenic Aid?’ Running Research News, vol. 9(1), pp. 1-5, 1993).

Prior to and following the six days of supplementation, the athletes ran four 300-metre and (on a separate day) four 1000-metre intervals, with three minutes of rest between the 300-metre work intervals and four minutes of recovery after the 1000-metre reps. Creatine dramatically improved the runners’ efforts. Compared to the placebo group, improvement in the final 300-metre interval (from pre- to post-supplementation) was more than twice as great for creatine users, and improvement was more than three times as great for creatine supplementers in the final 1000-metre interval. Total time required to run all four 1000-metre intervals improved from 770 to 757 seconds after creatine supplementation, a statistically significant change. Meanwhile, placebo-group members’ performances remained the same (about 775 seconds for the four intervals). Creatine supplementation improved the average quality of the 1000-metre intervals by a little over three seconds.

Of course, improvements in workout quality generally lead to improvements in competitive performances. Amazingly enough, workout-quality upgrades can occur after just five to six days of creatine supplementation. This all makes creatine sound wonderful, but there’s still that nagging problem of weight gain.

Will you always gain weight?
However, bear in mind that the water-retention-related gain in weight is primarily a function of the high creatine-loading doses (20 to 30 grams per day) used both in many research studies and by many athletes. In a very recent study, a lower loading dose (6g of creatine per day) produced only a one-pound gain in weight (‘Why Your Creatine Consumption Is Costing You Too Much,’ Running Research News, vol. 14(7), pp. 1-4, 1998).

And in fact researchers are finding that lower loading doses can be as effective as the big, 20-gram per day intakes at building up muscle creatine-phosphate concentrations, provided that the lower doses are taken over a little bit more time. Basically, the new research is revealing that six one-half gram doses of creatine per day (for a total of three grams daily) over the course of about 30 days will build muscle-creatine concentrations to a level comparable to that achieved with the whopping 20-gram ingestions. Very importantly, these three-gram per day intakes appear to be associated with very little water retention and weight gain.

Thus, it appears that creatine monohydrate can be a performance-boosting (and legal) supplement for endurance runners. The best way to take it is to simply sprinkle about a half-gram of the stuff on some food (and then of course eat the creatine and comestible) six times per day. Little creatine will be lost in the urine and faeces, creating a very economical intake pattern, little weight will be gained, and the resulting heightened intramuscular creatine-phosphate concentration should have a direct, positive impact on the quality of your high-intensity training sessions. Since intensity is the most potent producer of running fitness, your creatine-boosted sessions should eventually lead to some very nice PBs.

Bear in mind that there’s no need for you to buy ‘special’ creatine. ‘Micronized’ creatine and any commercial creatine product which supposedly can be absorbed more readily offers no special advantages; in fact, as the rate of creatine absorption increases, the urinary losses of creatine become greater.

Jim Bledsoe

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