Nitrogen Residual and Muscle Gain

Guest article by Martin MacDonald

WHY NITROGEN?

For the last couple of years, an test question I have set my undergraduates is 'How practice proteins differ chemically from lipids and carbohydrates?' The respond is: While carbohydrates and fat contain Carbon, Hydrogen and Oxygen, proteins also contain nitrogen. For this reason, we can use measures of nitrogen in the torso to assess the adequacy of an individual's protein intake.

WHAT IS NITROGEN BALANCE?

Nitrogen remainder does non necessarily hateful someone is taking in the same corporeality of nitrogen as they are using. Nitrogen rest is simply the measure of nitrogen output subtracted from nitrogen input. Therefore, if someone is taking in less nitrogen than they are excreting they are said to be in 'negative nitrogen residuum'. A negative nitrogen balance is associated with malnourishment and/or overtraining i.due east. catabolic processes are overriding anabolic ones. Conversely, a positive value is often found during periods of adequate and particularly over nutrition as well equally when resistance grooming acts every bit a stimuli for nitrogen/protein accrual. The figure below shows the possible fates of protein and therefore nitrogen in the body.

Incorporation of Nitrogen and Urea

MEASURING NITROGEN Rest?

Nitrogen balance and muscle gainMeasuring nitrogen remainder is at all-time, an estimation of both intake of nitrogen and excretion. Because of the incorporation of nitrogen into urea as shown in the figure to a higher place, loss of nitrogen is usually measured using urine, faecal and sweat nitrogen content. Losses may also occur through exhalation although, during exercise the errors in this measurement get in unreliable. Other issues accept been establish such as one identified by Wolfe et al. (1984) who constitute that light exercise increased the oxidation of leucine without increasing urea production. If this is the case, then protein needs for maintenance of musculus tissue may exist underestimated.

Other techniques which are perhaps more than accurate apply tracer techniques which utilize radioactively labelled tracers that are either ingested or infused. For instance, by infusing an amino acid with a radioactively labelled carbon, hydrogen, or nitrogen atom into an individual it is possible to measure the corporeality that is needed to get a balance with the amount being excreted. It is and so possible to measure whole body amino acid oxidation and degradation past measuring the amounts of radioactive carbon or nitrogen in the participant's breath or urine.

A very new technique is now being employed in a number of studies to look at poly peptide requirements. This method is called the indicator amino acrid oxidation (IAAO) method. Hither is a piffling explanation of it past Elango and colleagues (2008) who have washed a lot of work in this area since, some of which we will discuss later.

"The indicator amino acrid oxidation (IAAO) method is based on the concept that when ane indispensable amino acid (IDAA) is deficient for protein synthesis, so all other IDAA, including the indicator amino acid, will be oxidized. With increasing intakes of the limiting amino acid, IAAO will decrease, reflecting increasing incorporation into poly peptide."

If you didn't get that, try this analogy. Nosotros have a nightclub (your muscle) that has quite a lot of men in it (muscle fibres) so the doormen finish letting in guys (indicator amino acid) into the club. Therefore there is an excess of guys outside the club who can't get in so they get oxidised (couldn't think of an analogy for that 1… experience free to requite suggestions!). Nevertheless, if a guy is with a girl (indispensable amino acid) and then they are consummate (protein) and can get into the club… so! If we go a coach load of girls to come down and each i goes in with one of our excess guys we get less oxidised guys outside and more incorporation into the lodge! (MacDonald, 2011).

Hopefully you followed that. This really makes sense if you know anything about complete and incomplete proteins. On acme of this, we see that foodstuffs higher in leucine give united states of america a lower (practiced) IAAO. Studies using the IAAO method have shown that casein has a higher metabolic availability (MA) than soy protein (Humayun et al, 2007) so it must be a skilful method right…. ? Studies using the IAAO method are finding errors in old studies using other methods and the results are seemingly supporting what strength trainers have known for years. Nosotros'll await at these later on.

FACTORS AFFECTING NITROGEN Remainder

There are many things that will affect nitrogen balance and how much protein is needed to maintain this. Two major factors are energy intake and carbohydrate condition. The reason I accept included this section is so that based on your situation yous have an idea of whether mayhap your poly peptide needs are elevated. Very oft I meet individuals who want to gain musculus, yet, they yet train for and play football 2-iii times per week. At the same time, they might exist trying to go lean for a holiday and so they have reduced carbohydrates, sometimes drastically, because they are following some internet craze diet. In these instances, with free energy expenditure being high and carbohydrates beingness low or simply non high plenty because of the loftier intensity exercise, protein needs are drastically increased.

Below is a figure adjusted from Lemon and Mullin (1981) that shows sweat urea nitrogen (mg/h; a measure of nitrogen loss) in 3 different conditions. As you lot can come across, nitrogen losses with depression muscle glycogen levels are hugely increased. One thing to note here is that if an private is very well fat adjusted, I would expect to see a blunting of this nitrogen loss which signifies amino acrid oxidation.

Nitrogen Balance Article

POSITIVE NITROGEN BALANCE

Clearly different people have different goals and grooming modalities. This means recommendations for protein intake will vary accordingly. While strength and ability trainers may want to increase muscle size and therefore, desire extra protein for musculus growth, endurance trainers actually intermission downward a far greater amount of protein and take increased needs likewise. Something I accept to tell endurance athletes, peculiarly females, time and fourth dimension again is that eating poly peptide is not going to make them 'majority up'. Similarly, I spend a lot of time trying to get endurance athletes to understand that consuming protein immediately after training is benign not because it will 'rebuild their muscles' but because it volition stimulate synthesis of new enzymes (proteins) and mitochondrion (besides proteins!) which is part of adapting to preparation!

Every bit I take previously covered, older studies, employing less accurate measures of nitrogen balance may need to be discarded from time to come meta-analysis. Similarly, studies that only look at maintaining nitrogen balance, do not give united states of america an indication of the optimal protein intake for muscle gain! Very ofttimes studies are trying to ascertain the minimal protein requirement to maintain nitrogen remainder however, this clearly does not equate to an optimal protein intake. Strength athletes/trainers and bodybuilders are often interested in muscular hypertrophy, which volition require intakes well beyond levels required for maintenance. Interestingly, in that location is prove to suggest that nitrogen rest may exist able to occur at protein intakes that fall below those needed to optimize trunk limerick and performance measures.

A commonly cited study is the one shown in the figure below. Gontzea et al (1975) showed that when individuals undertake a new, unfamiliar, preparation schedule they become into negative nitrogen residue very rapidly simply that later on almost 2 weeks this normalises. The grooming used here was more than endurance based and therefore, nosotros however do not know what the difference would be if resistance exercise was used or if muscle hypertrophy was the goal.

PROTEIN INTAKES FOR POSITIVE NITROGEN Rest

Equally mentioned earlier, new techniques are becoming available to assess the adequacy of poly peptide intakes. Elango et al (2010) published a paper titled "Show that protein requirements have been significantly underestimated" in which they utilize the IAAO method to show that daily protein requirements are being grossly underestimated past other methods and that "at that place is an urgent need to reassess recommendations for poly peptide intake in adult humans." In this report they found requirement value should exist nearer of 1.2g/kg per 24-hour interval for sedentary individuals. Therefore, it is safety to presume if this technique is used to assess athlete's needs, the recommendations might be higher.

Currently the guidelines for exercising individuals are based on information in a newspaper by Lemon (1996). Recommendations for those who engage in regular endurance exercise are 1.two-1.4 g protein/kg body mass/d and for strength exercisers, 1.7-ane.8 g protein/kg trunk mass/d. Therefore, in coming years, we may see these recommendations going up to match what strength athletes are instinctively using which seems to be around 2-ii.5g/kg. In my stance, in non-drug using trainers, intakes of one.5-2g per kilogram are well in backlog of what is needed. Very high intakes of poly peptide merely lead to a greater breakdown and product of urea (waste product) whereas with normal, optimal, intakes of protein the salvage of urea via urea hydrolysis, is more efficient (Fouillet et al., 2008).

The unfortunate matter with many studies is that they but expect at 2-three levels of poly peptide intake to determine which is 'better' in relation to the goals they have outlined. Studies showing that 2.5g/kg BW of protein is better for strength and size gains versus ane.2g/kg BW practice not tell us whether 2.5g/kg is ameliorate than 2g/kg or indeed if 3g/kg would be better nonetheless. A written report published simply half-dozen months ago conducted at the Human Performance Laboratory, Birmingham, looked at the upshot of increased dietary protein on tolerance to intensified training. Witard and colleagues examined the effect of increased protein intake on short-term decrements in endurance operation during a block of high-intensity training. The control group consumed i.5g/kg BW protein while the intervention group consumed 3g/kg BW. The group concluded that

"Additional protein intake reduced symptoms of psychological stress and may result in a worthwhile amelioration of the performance refuse experienced during a block of loftier-intensity training."

Again, the reason I include this is that many people 'cross train' in the sense that they both run, cycle, play football and weight train all in the same week!

Some say that eating a very loftier protein diet produces a benign anabolic hormonal surround and it is this reason individuals should consume more than than is recommended by experts. Nonetheless, this does non seem to be the example and in fact, eating as well much protein at the expense of saccharide may well reduce the torso's levels of anabolic hormones such as testosterone. A study in 2007 past Ormsbee and colleagues also looked at the upshot of increased poly peptide intakes on levels of IGF-one, IGF-I, IGFBP-1, and IGFBP-3 which are hormones involved in musculus building. Intakes were l g, 100 g, or 200 g and showed no differences in serum concentrations of any of the hormones. Yet, what was noted was that the l thou/d of protein resulted in a negative nitrogen balance, whereas 100 g/d and 200 g/d resulted in a positive nitrogen balance with 200g/d existence significantly greater than 100 g.

For the individuals using advisable training methodologies to gain musculus, including periodization of this training, protein intakes of 2-2.5g/kg seem appropriate. If using supplementation such as creatine, leucine and whey protein, the protein needs may well be increased above normal because of the increased power to stimulate poly peptide synthesis and other anabolic processes. It is also useful to note that some class of protein cycling may be benign. So that when a new cake of training is started, more than poly peptide is consumed. Also, when energy intake or carbohydrate intake go down, poly peptide intake must get upward concomitantly.