ACSM Information On…

PROTEIN INTAKE FOR OPTIMAL MUSCLE MAINTENANCE
Resistance training is an important part of a complete exercise regimen. Consuming the appropriate amount and type of protein tomaintain and build muscle is just as important.
A Complete Physical Activity Program
A well-rounded physical activity program includes
aerobic exercise and strength training exercise, but
not necessarily in the same session. This blend helps
maintain or improve cardiorespiratory and muscular
fitness and overall health and function. Regular physicalactivity will provide more health benefits than sporadic,
high intensity workouts, so choose exercises you arelikely to enjoy and that you can incorporate into yourschedule.
ACSM’s physical activity recommendations for healthy
adults, updated in 2011, recommend at least 30 minutesof moderate-intensity physical activity (working hardenough to break a sweat, but still able to carry on aconversation) five days per week, or 20 minutes of morevigorous activity three days per week. Combinationsof moderate- and vigorous-intensity activity can be
performed to meet this recommendation.
Examples of typical aerobic exercises are:
• Walking• Running• Stair climbing• Cycling• Rowing• Cross country skiing• Swimming
In addition, strength training should be performed aminimum of two days each week, with 8-12 repetitionsof 8-10 different exercises that target all major muscle
groups. This type of training can be accomplished using
body weight, resistance bands, free weights, medicine
balls or weight machines.

What is Protein?
In the human body, proteins are a part of every
cell and tissue, including our muscle. Ourbodies are constantly recycling proteins on adaily basis. The proteins that we eat in our dietcan be used to replace broken down proteins inorder to maintain balance.
Proteins contain essential and non-essential
amino acids. Amino acids are the building
blocks for all our proteins in the body. Essential
amino acids are those that our body cannot
make on its own and thus, these amino acids
must come from the foods we eat. A complete
protein is named just that because it willcontain all of the essential amino acids ourbody needs to repair and grow. These proteins
sources are animal-based and include meat,poultry, fish, eggs and cheese. Foods like rice
and dry beans also contain protein, but may nothave all the essential amino acids our bodies
need. However, when combined together, these
two foods can provide adequate amounts of all
the essential amino acids.
Protein can be found in relatively highconcentrations in the following foods:• meats, poultry, and fish
• legumes (dry beans and peas)• tofu• eggs• nuts and seeds• milk and milk products (cheese and yogurt)• grains, some vegetables and some fruits(provide only small amounts of protein
relative to other sources)

Protein intake from animal sources rather
than plant-based sources tend to have better
absorption rates. However, even vegetarians canachieve adequate protein intake when a varietyof plant sources are included ensuring intake ofall essential amino acids.
Here are some practical protein equivalents incommon foods:• One cup of milk has eight grams of protein• One cup of soy milk has about seven gramsof protein• One egg has six grams of protein• A three ounce piece of meat has about 21grams of protein• One cup of dry beans has about 16 grams ofprotein• An eight ounce container of yogurt has about
11 grams of protein

Recommended Intakes of Protein
In general, it is recommended that 10-35
percent of your daily energy intake comes fromprotein. If you consume 2,000 calories per day,this would work out to be between 200 to 700
calories of protein per day. The recommended
daily intakes (RDIs) can also be calculated
by a person’s body weight. The Academy ofNutrition and Dietetics recommends that theaverage individual should consume 0.8 grams ofprotein per kilogram or 0.35 grams per poundof body weight per day for general health. So a
person that weighs 75 kg (165 pounds) should
consume an average of 60 grams of protein perday. Since there are approximately four calories
per gram of protein, 60 grams of protein would
result in the intake of 240 calories.

Muscle mass is built when the net proteinbalance is positive: muscle protein synthesis
exceeds muscle protein breakdown. Researchshows muscle protein turnover is the greatest
after working out. Additionally, it has beenshown that muscle mass increases over time
when resistance exercise (i.e. weight lifting,body weight exercises, etc) is combined withnutrient intake.
However, as we age, we need to increase ourprotein intake. Around 50 years of age, weneed to increase the protein in our diets to
one gram per kilogram of our body weight tomaintain muscle mass. People that exercise
regularly also need to eat more protein than therecommended daily intake.
To increase muscle mass in combination withphysical activity, it is recommended that aperson that lifts weights regularly or is training
for a running or cycling event eat a range of
1.2-1.7 grams of protein per kilogram of bodyweight per day, or 0.5 to 0.8 grams per poundof body weight. Consequently, the same 75
kilogram individual should increase theirprotein intake to 75 grams (300 calories) to 128
grams (512 calories) in order to gain muscle
mass. This level of intake can generally be met
through diet alone and without additional
protein and amino acid supplementation.

When Should I Consume My Protein?
The process of protein turnover is increasedwith resistance training and can remain
elevated for up to 48 hours in people beginninga new resistance training program. Therefore
it is important to provide enough energy
including protein so there is a sufficient pool ofamino acids available to repair and build newmuscle. Of course, you do not want to exercise
on an empty stomach. In fact, exercising in an
unfed state leads to an increase in protein loss
making it more difficult for the body to both
repair and build muscle.
Research suggests there are several benefits
to pre-exercise protein supplementation.
Pre-exercise protein supplementation helps
to improve body composition by increasing
resting energy expenditure up to 48 hours after
exercise. This is important because it suggeststhat pre-exercise protein ingestion will not
only help increase lean muscle mass and thus
strength, but will also simultaneously reduce
fat mass. However, the most scientificallysupported and most significant benefits ofconsuming protein prior to exercise may be
improved recovery and hypertrophy. This isthought to occur because of improved aminoacid delivery.
Protein supplementation after exercise may
have a more profound impact on skeletal
muscle hypertrophy. Several studies havedemonstrated that protein ingestion following
an acute bout of resistance training stimulates
muscle protein synthesis for up to threehours. In contrast, failing to eat after exercise
may limit protein synthesis and therefore
limit potential progress in lean muscle tissue
development. Research actually suggests
there may be an “anabolic window” such that
protein intake within an hour of exercise has
the greatest influence on resistance training
adaptations.

What Proteins Should I Consider?
Whey protein is beneficial in supportingmuscle adaptations due to its rapid absorption
rate in addition to casein that has a slower andmore sustained rate of amino acid absorption
over a few hours. Branched chain aminoacids are similarly beneficial and have beenshown to aid in recovery from exercise withrespect to not only protein synthesis but also
aiding in replacing our muscle glycogen anddelaying fatigue associated with exercise.
Generally, naturally occurring animal proteins
contain 2:1:1 ratio of leucine, isoleucine andvaline. These proteins have been identified
as providing optimal support of muscle
adaptations with exercise training. In order tomeet the recommended RDA a consumptionof approximately 45 mg/kg/day of leucine and22.5 mg/kg/day of isoleucine and valine issuggested.

Summary
Protein supplementation has been shown to
improve muscle building with regular exercise
training. A diet based on the current protein
intake recommendations may be achieved
through a balanced diet and does not require
additional supplementation. The benefits ofresistance training and protein timing are notlimited to sports performance or improving
physique but can also delay the onset of agerelated muscle loss and help preserve muscle
mass and strength in the elderly helping tomaintain independence and quality of life.

Staying Active Pays Off!
Those who are physically active tend to live longer,
healthier lives. Research shows that moderate physicalactivity—such as 30 minutes a day of brisk walking—significantly contributes to longevity. Even a personwith risk factors like high blood pressure, diabetes
or even a smoking habit can gain real benefits fromincorporating regular physical activity into their dailylife.
As many dieters have found, exercise can help you
stay on a diet and lose weight. What’s more – regularexercise can help lower blood pressure, control blood
sugar, improve cholesterol levels and build stronger,
denser bones.

The First Step
Before you begin an exercise program, take a fitness test,or substantially increase your level of activity, make sure
to answer the following questions. This physical activity
readiness questionnaire (PAR-Q) will help determine if
you’re ready to begin an exercise routine or program.
• Has your doctor ever said that you have a heart
condition or that you should participate in physicalactivity only as recommended by a doctor?
• Do you feel pain in your chest during physical activity?
• In the past month, have you had chest pain when you
were not doing physical activity?
• Do you lose your balance from dizziness? Do you everlose consciousness?
• Do you have a bone or joint problem that could bemade worse by a change in your physical activity?
• Is your doctor currently prescribing drugs for yourblood pressure or a heart condition?
• Do you know of any reason you should not participate
in physical activity?
If you answered yes to one or more questions, if you areover 40 years of age and have recently been inactive,
or if you are concerned about your health, consult aphysician before taking a fitness test or substantially
increasing your physical activity. If you answered no toeach question, then it’s likely that you can safely begin
exercising.

Prior to Exercise
Prior to beginning any exercise program, including
the activities depicted in this brochure, individuals
should seek medical evaluation and clearance to engage
in activity. Not all exercise programs are suitable foreveryone, and some programs may result in injury.
Activities should be carried out at a pace that is
comfortable for the user. Users should discontinue
participation in any exercise activity that causes pain ordiscomfort. In such event, medical consultation shouldbe immediately obtained.

ACSM grants permission to reproduce this brochure if it is reproduced in its entirety without alteration. The text may be reproduced in another publication if it is used in its entirety
without alteration and the following statement is added: Reprinted with permission of the American College of Sports Medicine. Copyright © 2015 American College of Sports Medicine.
This brochure was created and updated by Donna Cataldo, Ph.D. and Matthew Blair, B.S., and is a product of ACSM’s Consumer Information Committee.
Visit ACSM online at www.acsm.org.