I recently had a discussion with some training buddies what we considered was the most important supplement. The premise was, if you could take only one thing, what would you take? My answer was protein. Certainly, my response was influenced by the importance of protein in achieving success in the gym, but beyond that, protein is an essential component of virtually every cell in the body and also plays a crucial role in the formation of hormones, enzymes and antibodies, not to mention energy production. Clearly, anything but optimal levels of protein will affect you much more than just looking like a broomstick.
Telling you that a highly active person's protein needs are greater than those of the sedentary person is nothing new. If I said you should take in about 1-1.5 grams of protein per pound of bodyweight each day, you won't fall off your chair in amazement. But if I told you that the amount of protein you ingest should vary depending on how you exercise, now we're talking serious stuff. The problem is, we didn't really know too much about this until recently.
Peter Lemon, PhD, and colleagues from the applied physiology research laboratory at Kent State University in Ohio set out to determine to what degree protein needs may vary depending on how intensely you train. They recruited six healthy, physically active men who exercised on a treadmill for one hour at a low (42%), moderate (55%) and high (67%) level of intensity as determined by the subjects maximal oxygen consumption and use rates (VO2 max). To make sure diet didn't confound the results, each subject consumed the same kind of mixed diet throughout the experiment.
Now, the primary method to determine protein needs was to see how much nitrogen the subjects lost in response to training. Nitrogen is a byproduct of protein and amino-acid metabolism; so measuring the amount of nitrogen excreted can result in fairly accurate estimates of protein use. To increase the level of accuracy, Lemon and colleagues looked at subject's urine concentrations of nitrogen as well as that of sweat for two day's after exercising. As expected, both urine and sweat nitrogen levels increased in response to training. In fact, total nitrogen excretion was elevated 24-48 hours after exercise.
Let's be more specific: The moderately trained group lost 4.6 grams of nitrogen and the intensely trained group lost 7.2 grams over the three-day experimental period significantly more than what the low-intensity and control groups experienced. Moreover, this difference represents a 16%-25% increase in protein need for people exercising at moderate and high intensities.
Here's my take on this research. First, how intensely you train obviously affects your protein needs. Second, I don't consider training at 67%, of VO2 max as tremendously intense. For the most part, bodybuilders go quite a bit beyond that when they' train aerobically. Then we need to consider that they pump a considerable amount of iron, too, so protein needs could be even greater.
To me, here's the most important take-home lesson: You can't just increase your protein requirements by 25% and leave it at that. Consider how intensely you train and make adjustments accordingly. If you train hard, go for it and consume about 1.5 grams of protein per pound of bodyweight daily. If you follow a low-intensity training program, take in about 1-1.2 grams of protein each day. If you're taking time off, consume slightly less. My reasoning? Not only do your needs change in response to training, but consuming more protein than you need won't make you bigger. In fact, it could result in greater fat deposits and certainly a lighter wallet.