Protein
has many essential roles in the body and is a nutrient that is
found in many animal and plant foods. Dietary protein has two
possible fates – it can either be used in growth and repair
(eg muscle, haemoglobin or antibodies) or burned for energy like
carbohydrate and fat. About 15% of body weight is made up of protein,
and most of this is found in skeletal muscle, which explains the
importance of protein for athletes.
The protein we eat is made up of 20 amino acids (building blocks);
the process of digestion breaks down dietary protein into its
amino acids, which are then absorbed and reassembled to make various
kinds of human protein such as muscle, connective tissue and immune
proteins.
Protein activity in the body is in a constant state of change;
when dietary protein is insufficient, muscle protein can be broken
down to provide amino acids for essential body functions such
as immune function. This explains why muscle mass is often lost
during times of stress, disease or poor nutrition. On the other
hand, when dietary protein is in plentiful supply, muscle mass
can be maintained or increased.
Do
athletes need more protein?
In a word, yes. Strength and power is generated by muscles and
strength athletes benefit from maximising muscle mass. Endurance
athletes need to maintain sufficient muscle mass as high training
volumes increase the use of protein as a fuel. However it is not
as simple as just loading up on protein foods or supplements without
considering the diet as a whole.
Research
has shown that even though protein requirements of athletes are
higher than those of sedentary people, there is a limit to the
amount of protein that the body can use to increase muscle strength
– amounts above about 1.8g/kg body weight will generally
be stored as fat. What is more important is the timing of protein
intake, that is, when protein is eaten in relation to training
schedules.
Protein
requirements:
| Type
of Athlete |
Daily
protein requirements per kg body weight |
| Endurance
– moderate or heavy training |
1.2
– 1.4g |
| Strength
and power |
1.4
– 1.8g |
| Fat
loss programme |
1.6
– 2.0g |
| Weight
gain programme |
1.6
– 2.0g |
Ready
reckoner of protein foods
Food
portions containing approximately 20g of animal protein
| Animal
Source |
Approx
weight |
Calories |
Handy
measure |
| Beef,
lamb, pork
Turkey, chicken
Grilled liver
Grilled fish
Grilled fish fingers
Salmon in brine
Tuna in brine
Prawns
Eggs
Cheddar cheese
Edam cheese
Cottage cheese
Milk, semi-skimmed
Yogurt, low fat
|
75g
75g
100g
100g
100g
100g
100g
100g
-
75g
75g
150g
1 pint
500g
|
3oz
3oz
4oz
4oz
4oz
4oz
4oz
4oz
-
3oz
3oz
6oz
20oz
|
115
105
190
95
200
165
100
105
240
300
230
150
280
450
|
2
medium slices
1 small fillet
2 tablespoons
1 small fillet
6 fish fingers
1 small tin
1 small tin
2 tablespoons
3 medium size
2 matchbox size pieces
2 matchbox size pieces
4 tablespoons
1 pint
4 cartons
|
Foods
portions containing 10g of vegetable protein
| Vegetable
Source |
Approx
weight |
Calories |
Handy
measure |
| Nuts
(peanuts, cashews)
Seeds (sunflower, sesame)
Baked beans
Kidney beans/split peas/lentils
Tofu (soya bean curd)
Soya milk
Peanut butter
Bread
Pasta eg spaghetti
Noodles
Rice
Potatoes
Cornflakes
Weetabix
Digestive biscuits
|
50g
50g
200g
150g
125g
350ml
50g
125g
250g
450g
450g
600g
125g
100g
100g
|
2oz
2oz
8oz
6oz
5oz
14fl
2oz
5oz
9oz
16oz
16oz
21oz
5oz
4oz
4oz
|
295
290
160
150
90
110
310
270
260
280
555
480
460
340
700
|
1
medium packet
4 tablespoons
4 tablespoons
5 tablespoons – cooked
½ packet
approx 2/3 pint
1 ½ tablespoons
4 large slices
8 tablespoons – cooked
12 tablespoons
12 tablespoons – cooked
8 medium
2 large bowls
5 weetabix
9 biscuits |
Timing
of intake
Straight
after hard training is when muscle protein synthesis is increased.
Therefore it is important that the right raw materials are available
to maximise this. However increasing protein intake at the expense
of carbohydrate is a bad strategy for athletes in heavy training,
because without sufficient carbohydrate, the muscle glycogen stores
cannot be refuelled and energy available for the next exercise
session will suffer. So the ideal recipe is to take both carbohydrate
and protein straight after hard sessions, to maximise muscle conditioning
and start refuelling. Athletes should aim to consume 1g carbohydrate
per kilo body weight and 0.25g high quality protein per kilo body
weight within 30 minutes of finishing training. In addition to
this plan, athletes should include protein at all other meal times
to ensure a steady supply of amino acids to body cells.
Type
of protein
There is much debate on what the ‘best’ type of protein
is. Whey protein and casein are the two major types of protein
found in milk, and are often the ones used in protein supplements.
All animal protein (from milk, eggs, meat, fish and poultry) provide
the highest quality rating of food sources. However plant proteins
(breads, cereals, peas, beans, pulses, nuts) also contain significant
amounts of protein, but need to be combined to produce the same
quality as animal sources. A food-based approach to meeting protein
requirement should be the focus for athletes.
Protein
supplements
These are popular with athletes trying to increase muscle size.
Whereas it is accepted that athletes need more protein than non-athletes,
there is no evidence that supplements offer advantages over dietary
sources of protein. The mistake athletes often make is to take
a protein supplement at the expense of carbohydrate straight after
training; what is needed at this time is both protein and carbohydrate.
This can be taken as ordinary food or as a liquid supplement (that
includes both high quality protein and carbohydrate). For athletes
who are liable to be drug tested, remember taking any supplement
is at their own risk.
Are
very high protein intakes harmful?
There is not much evidence to show that high protein intakes are
harmful, but there are concerns around the effects they can have
on hydration and bone health. Very high protein intakes increase
water and calcium loss due to the increased excretion of protein
waste products. Often high protein intakes result in athletes
not consuming enough carbohydrate foods to support their fuel
needs for intensive training.
Ruth
Wood-Martin
Accredited Sports Dietitian |