Muscular Development – July 2019

July 2019 musculardevelopment.com MD 61

nitric oxide in the body, but they can also work

by counteracting the vasoconstrictive actions

of certain enzymes in the body, such as

angiotensin-converting enzyme (ACE).

Now, in regard to boosting nitric oxide,

supplements accomplish this via one of two

distinct NOS (nitric oxide synthase) pathways

in the body— the NOS-dependent pathway or

the NOS-independent pathway.

The NOS-dependent pathway is the most

well known among bodybuilders, and it’s where

L-arginine is converted to nitric oxide (NO) via a

set of nitric oxide synthases.^7 Now, a number of

arginine-based compounds have been released

over the years, yielding mixed results in terms

of effectively boosting nitric oxide.

The problem with arginine is that it has

rather poor bioavailability in the body, meaning

that in order to get any tangible increase in

blood flow and cellular swelling, you would

have to take rather large doses of it (>10g).

However, taking large doses while potentially

yielding greater NO production also comes with

the rather unwanted side effect of horrendous

gastrointestinal distress and diarrhea.^8

Fortunately, scientists have stumbled on

an ingredient that is more bioavailable (and

effective) than L-arginine, as well as one that

doesn’t come with horrendous gastrointestinal

distress in L-citrulline malate. Composed of

L-citrulline (an amino acid found in watermelon)

and malic acid (an organic acid naturally

occurring in apples, citrulline malate is more

efficiently used by the body and not subject

to breakdown by arginase, the enzyme that
degrades arginine and ultimately limits nitric
oxide production, vasodilation and muscle
pumps.^9 Clinical trials have demonstrated that
a pre-workout containing 8 grams of citrulline
malate per serving will improve repetitions
completed and total work performed during
multiple sets taken to failure.10,11,12 Other studies
note that citrulline malate supplementation
enhances oxygen kinetics, time to exhaustion
and total work performed during a high-
intensity exercise.
Basically, powerful vasodilators, such as
citrulline malate, increase blood flow to the
working muscle, enabling you to perform
higher amounts of work and drive more blood
JASON BREEZE to the muscle, which increases metabolites and

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