Exercise and Protein Supplements

Original Editor - Megan Landwehr as part of the University of Oklahoma Exercise Science Project Top Contributors -

Introduction[edit | edit source]

Protein powder.jpeg

Containers of protein powders line the shelves of many supplement stores and are typically a highly purchased product. Protein supplements can be used for a variety of reasons such to help build muscle mass, help with exercise recovery, and can even be used as a meal replacement. Due to the wide variety of usages, this supplement will be used by many types of people and found commonly in a physical therapy clinic.

As a physical therapist it is helpful to know:

  • how protein metabolizes,
  • the different types of protein supplements
  • the effects on timing of ingestion of protein supplements
  • how protein effects different types of exercise
  • how age influences protein supplementation
  • any additional side effects protein supplements may have.
  • encourage optimising nutritional intake through the introduction of protein-rich whole-foods, isolated proteins and nutrient compounds, and query the need for additional protein (possible dietician referral)

Regular dietary supplementation with protein or essential amino acids (EAA)

Shown to augment skeletal muscle strength and mass in:

  1. Healthy adults
  2. Patients with a chronic condition eg:coronary artery disease, chronic heart failure, type 2 diabetes mellitus, chronic obstructive pulmonary disease, osteoporosis, the metabolic syndrome and dementia.

This is most likely due to the capacity of dietary protein and/or EAA supplementation to stimulate the mammalian target of rapamycin (mTOR) pathway and muscle anabolism.

Protein and/or EAA supplementation may therefore help to improve strength and muscle performance in such patients.[1]

Types of Protein Supplements [edit | edit source]

There are many different types of protein powders but most consist of powdered forms of protein from soy, pea or dairy (whey or casein) with or without carbohydrates and other performance-enhancing ingredients like creatine, ‘fat metabolisers’, vitamins and minerals. When you mix them with water or milk, they turn into a milkshake or smoothie-type drink.

  • Take a look at the ingredients list and check for additives such eg vegetable gums, thickeners, artificial sweeteners, artificial flavours and indigestible fibre (inulin), some of which commonly cause symptoms like bloating, gas, nausea and diarrhoea[2]. Try to avoid these.

Protein powders come from a variety of sources and are available in several formulations. People use them to increase muscle mass, improve overall body composition and help meet their protein needs.

The most common types of supplementation include: Whey, Casein, and Soy.

Image 2: % of Hydrolysis graphed against time. Hydrolysis is a form of digestion that breaks down proteins into smaller peptides, or amino acid chains.[3]

  1. Whey
Degree of Hydrolysis vs. Time in Different Protein Types

The leucine, isoleucine, and valine content in whey and its ease of digestibility make it one of the highest-quality proteins [4]. Whey is a protein that is a by-product in cheese production. Whey accounts for 20% of the protein found in milk. This protein metabolizes fast and is the most popular type of the three. Whey is also high in muscle-building amino acids like leucine, isoleucine, and valine. There are two main types of whey protein sold as well as a blend of the two together. These variations are Whey Isolate and Whey Concentrate. Isolate tends to be higher quality and contains between 90 and 98% protein. Concentrate contains between 70 and 85% protein [5]. Muscle hypertrophy occurs at a greater rate with the consumption of whey protein over soy or casein[4].

2. Casein

Casein is a protein that makes up the remaining 80% of the protein in milk. Casein digests slowly and is a popular choice as a weight gainer. It contains a little more than 90% protein in general and encourages the body to metabolize carbs and fats first. Casein is also a popular choice for muscle building.

3. Soy

Soy protein is a fast digesting protein that is of high quality. It is not as efficient as the milk proteins; therefore, it is not as desirable for those looking to build muscle.

Soy protein supplementation has had a lot of controversy over its effect on muscle through use with resistance training, but also the positives and negatives of some of its potential side effects. The main content of soy protein supplements is the soy bean. In a 2006 study, the effects of whey and soy protein with resistance training young men and women in comparison to a blinded control group. The results showed that soy protein in combination with resistance training produces the same effects as whey protein supplementation. [6][7]

Protein Metabolism and Effects on the Body[edit | edit source]

Digestion and Absorption of Proteins

Protein metabolism in the body occurs differently from the other macronutrients, as there is no type of storage for proteins (there are three macronutrients: protein, fats and carbohydrates).

  • Proteins are composed of Carbon, Hydrogen, and Oxygen, and Nitrogen.
  • Amino acids are the building blocks of proteins, and are connected by peptide bonds [8].

There are

  1. 9 essential amino acids that must be consumed
  2. 11 non-essential amino acids that can be synthesized in the body.

A complete protein contains all 9 essential amino acids ( eg.animal products and soy)

An incomplete protein lacks one or more essential amino acids (commonly seen in plant sources).

Protein metabolism

Each protein consists of as many as 2,000 amino acids connected by chemical links called peptide bonds. Whole proteins are too large to be absorbed into the bloodstream, so during digestion they're metabolized (ie broken down).

  • This process begins in the stomach, where the enzyme pepsinogen is converted to the active pepsin form when in the presence of the highly acidic hydrochloric acid (HCl). Pepsin begins to break down the peptide bonds to form dipeptides and amino acids.
  • Enzymes, including Trypsin, Chymotrypsin, and Carboxypeptidase, from the pancreas and small intestine are also secreted when needed to break any remaining peptide bonds that escaped the stomach.
  • The amino acids are then absorbed in the small intestine and released in the blood stream [9].
  • Your digestive tract can absorb up to 10 grams of amino acids per hour, so you'll absorb all the protein in a reasonably sized meal in the hours after eating. In the end, the body has plenty of time to absorb more than 90 percent of the protein ingested[10].
Protein image.jpeg

Proteins (image R: Molecular model of a protein). are responsible for a number of roles in the body. (carbohydrate and fats can be used for energy, proteins do not supply energy directly to the body).

  • Amino acids circulating in the bloodstream are used primarily to build new proteins. Protein synthesis takes place inside each cell. Special molecules collect amino acids from the bloodstream, take them back to the cell, then assemble them in the particular order needed to produce the protein. If you eat a balanced diet, you'll have all the amino acids required for protein synthesis from your food. If you aren't eating enough, though, your body might start breaking down muscle tissue as a source of amino acids.[10] (see eg sarcopenia, muscle function and protein))
  • Proteins: play a central role in biological processes. For example: proteins catalyse reactions in our bodies (enzymes); transport molecules such as oxygen (the oxygen-binding protein hemoglobin); build muscles; keep us healthy as part of the immune system (eg Antibodies); transmit messages from cell to cell (cytokines). [11][8].

Timing of Protein Supplementation[edit | edit source]

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Before and/or During Exercise:

  • Minimal research exists supporting the positive impact of protein supplementation before or during exercise. The majority of studies completed have been inconclusive[12]

After Exercise:

  • Protein plays a very important role in the recovery process following exercise. Whether ingested in in the form a powder supplement listed above or a high quality, whole foods meal, protein acts as a catalyst to jumpstart and improve muscular adaptations. One study showed that, "A post-exercise protein meal accelerates recovery of static force and dynamic power production during the delayed onset muscle soreness (DOMS) period"[13]. A recent systematic review showed that the intake of protein after exercise has "beneficial effects such as reduced muscle soreness and markers of muscle damage"[14].
  • Besides exercise recovery, research shows post-exercise consumption of protein supplements can also result in improved muscular adaptations. "The intake of protein after resistance training increases plasma amino acids, which results in the activation of signaling molecules leading to increased muscle protein synthesis and muscle hypertrophy"[15]. "Dietary protein ingestion after exercise increases post-exercise muscle protein synthesis rates, stimulates net muscle protein accretion, and facilitates the skeletal muscle adaptive response to prolonged exercise training"[12].
  • Researchers have investigated the impact of amino acid (lysine, proline, alanine, and arginine) and/or conjugated linoleic acid (CLA) supplements administered before and after aerobic exercise on body weight, percentage body fat, waist-hip circumference, triglycerides and LDL-cholesterol levels [16]. When compared to the placebo group, results showed that waist-hip circumferences and BMI improvements of the experimental group after aerobic exercise were clinically significant.

Types of Exercise and Protein Supplementation[edit | edit source]

Aerobic Exercise 

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  • Energy and macronutrient needs, especially carbohydrate (CHO) and protein (Pro), must be met during times of high physical activity to maintain body weight, replenish glycogen stores, and provide adequate protein to build and repair tissue. 
  • Endurance athletes usually take CHO supplements during long bouts of exercise to replenish their glycogen stores in order to continue their workout. Studies have been done to prove that carbohydrate-protein (CHO-Pro) supplementation taken after a bout of exercise improves the performance of an endurance athlete and if ingested during a bout of exercise protein oxidation is increased[17].
  • Improved recovery and less muscle damage have been associated with CHO-Pro drinks post-exercise.
  • CHO-Pro drinks have a lot of potential for endurance athletes during and post-exercise.

Anaerobic Exercise

  • There has been limited research to show how protein supplementation effects anaerobic exercise.[18] But, increases in lean body mass correlates to resistance training and consumption of protein.
  • Some research has shown that "protein supplements following daily training for several weeks will enhance gain in VO2max in previously untrained individuals or athletes at the beginning of their seasonal training programs or result in improvements in tests of aerobic and anaerobic power for athletes during their normal trianing programs".
  • For some resistance trained individuals, strength is their goal for training. Muscles with a greater cross sectional area are able to produce more force. Protein supplementation has been proven to decrease the amount of muscle degeneration after a bout of exercise[4]
  • Further reasearch is needed to determine how protein supplementation can effect gains in anaerobic power. 

Protein Supplementation in Trained vs Untrained Athletes[edit | edit source]

  • Protein supplementation's ability to increase hypertrophy and decrease muscle soreness following resistance training makes it a popular choice among every level of athlete.[15][12] 
  • Recent research suggests that during the first few weeks of exercise, it is unlikely for protein supplements to show any impact on lean mass and muscle development in untrained individuals.[18] As intensity, frequency, and duration begin to increase and grow, protein supplements will then become advantageous.[18]

Implications for Physical Therapy[edit | edit source]

Protein shake.jpeg

It is important for a physical therapist to know if their patient is taking protein supplementation in order to help educate them about their protein intake routine and to inform them of potential side effects. Physical therapists can also use their platform to inform their patients about the benefits of protein. Research suggests protein can positively affect those with chronic obstructive pulmonary disease (COPD), heart failure, and chronic kidney disease (CKD) but research needs to be furthered to fully support these claims. These are only some examples of how protein intake can affect patients in the clinic. This section will further discuss some of the ways an increased protein intake can improve a patient’s functional abilities.

Cerebrovascular Accidents (CVA)

According to a study in 2014, strokes are the world's leading cause of disibility[19]. The American Heart Association found that 16% of patients with strokes admitted to the hospital are malnourished. After just one week in the hospital, 24% of patients with CVAs are considered malnourished. Patients who have experienced a stroke have lowered levels of protein synthesis when compared to a those who have not. Therefore, patients that experienced a CVA tend to have lower muscle mass and strength. If a patient is not synthesizing proteins correctly, there is a positive correlation with a poor outcome in rehabilitation[20].
Those who have suffered a stroke have difficulties with their non-paralyzed side of the body due to a “muscle fiber shift, an increase in intrasmuscular fat, spasticity, disuse, malnutrition, and muscle unloading[19]”. It was discovered that the unaffected side of the body becomes hypercatabolic due to excess of protein breakdown. Protein synthesis (anabolic activity) is lower in the unaffected side as compared to healthy individuals. In this double-blind randomized control trial, subjects were separated into two groups: a group to received essential amino acid supplements (2.5 g of leucine) and a control group and received a placebo. This study suggests amino acid infusion can increase the protein synthesis of myofibrillar, sarcoplasmic, and mitochondrial proteins by 30%[21]. Ultimately, protein ingestion can help decrease the natural degradation rate of muscle proteins in patients who have recently had a stoke. 

Obesity

Obese patients often have a reduced ability to move through full range of motion due to excess soft tissue. There have been multiple studies that suggest an increase in protein can help obese patients lose body fat and gain lean muscle, which in turn increases their range of motion (ROM).
According to a randomized control trial there is evidence showing consumption of whey-protein can decrease body fat while preserving lean muscle mass amongst those who are classified as obese. In this specific study, the patients who drank two protein shakes per day saw a decrease of 6.1% in their body weight. This amount decrease is statistically significant to support a lower risk for obesity related diseases. [22]
Another study focused on aging obese patients with a focus on increased protein levels naturally- not through supplementation. This study suggests protein intake is important because those who are obese often cannot “achieve a level of physical training sufficient to induce a negative energy balance”.[23] Patients who are looking to lose weight but cannot function enough to complete physical activity at the appropriate level can benefit from increasing their protein intake- either through supplementation or through a change of eating habits. A greater outcome in rehabilitation is expected if a patient can have a higher ROM. Protein intake can increase an obese patient’s functional performance.

Sarcopenia

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Sarcopenia is the gradual and progressive process of muscle mass loss and strength that is associated with aging. Participating in aerobic and resistance exercise programs has shown to lessen many aspects of sarcopenia. Along with regular exercise, proper nutrition- especially protein, is essential and can help reduce and treat declines in muscle mass. While sarcopenia is thought to be a natural part of the aging process, other factors should be considered. For instance, older adults tend to intake fewer calories, including less protein. Older adults are failing to meet their protein needs, which ultimately results in sarcopenia.[24] Patients suffering from sarcopenia can be a concern for health providers because it leads to fraility, which raises the concern for falls and fractures.  

Age Effects and Recommendations of Protein [edit | edit source]

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The recommendations for protein intake vary during different stages of life, gender, and activity level. The Estimated Average Requirements (EAR) for protein ranges from anywhere from 0.66 to about 1 gram of protein per kilogram of body weight. The Recommended Dietary Allowance (RDA) is similar to the EAR and suggests the daily requirement for adult men and women ranges from 46 to 56 grams each day[9]. Different ages and stages of life are also important to consider when recommending protein intake, due to varying requirements.

Protein requirements are increased at times of growth and development. Therefore, more protein is needed during the first year of life and during pregnancy and lactation. Protein requirements are also increased as men and women age, due to the decrease in efficiency of absorption and digestion, as well as the increase in excretion of protein in the urine.

  • Seniors may need 1.0-1.3 grams of protein for every kilogram of body weight. eg if you weight 82 kg this could mean consuming 80-104 grams of protein every day, regardless of your calorie intake. The current protein RDA does not appear to meet the optimal protein requirements for older people to maintain skeletal muscle mass[25].
  • During the first year of life, infants grow at an exponentially faster rate than at any other time in their life and have an increased need for protein. Infant’s nutrition comes from the mother’s milk, which is extremely rich in protein.
  • During pregnancy and lactation, it is suggested that women increase protein intake to about 71 grams per day, to support their child’s growth [9].

Additional Side Effects[edit | edit source]

Blood Glucose Levels.png
  • Several studies have shown that increased protein intake through the use of protein supplements can have the effect of lowering both systolic and diastolic blood pressure. Its use may therefore be beneficial in managing the blood pressure of those with hypertension. However, one needs to exercise caution with protein supplementation for those whose blood pressure is already low or who are taking medication that lowers blood pressure, as it may increase hypotension-related risks.[26][27][28][29][30] 
  • Because protein intake also causes an increase in blood insulin levels, studies have shown that it can significantly lower blood sugar levels. This effect is most pronounced following the ingestion of whey protein, but is still noticeable with the ingestion of protein from other sources.[31][32][33][34] The following graph is from a study comparing blood glucose levels after ingesting a plain glucose drink with blood glucose levels after ingesting the same glucose drink mixed with whey protein: 
  • Blood glucose levels were clearly much lower when whey protein was ingested.[33] It is important to be mindful of this effect on blood sugar levels when one already has low blood sugar or when one may be taking insulin for diabetes. Failing to do so could potentially increase dangerous hypoglycemia-related risks.

Conclusion[edit | edit source]

As a physical therapist, the likelihood of encountering protein supplementation in the clinic is high. Understanding its function within the body is important to properly educate the community and assure that supplementation is being used in a way that is research supported to efficiently maximize benefits for each individual person. 

References [edit | edit source]

 

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  29. He J, Gu D, Wu X, Chen J, Duang X, Chen J, Whelton P. Effect of soybean protein on blood pressure: A randomized, controlled trial. Annals of Internal Medicine 2005; 143(1): 1-9. doi:10.7326/0003-4819-143-1-200507050-00004
  30. Teunissen-Beekman K, Dopheide J, Geleijnse J, Bakker S, Brink E, Leeuw P, Baak M. Protein supplementation lowers blood pressure in overweight adults: Effect of dietary proteins on blood pressure (PROPRES), a randomized trial. American Journal of Clinical Nutrition 2012; 95(4): 966-971. doi:10.3945/ajcn.111.029116
  31. Pal S, Ellis V. The acute effects of four protein meals on insulin, glucose, appetite and energy intake in lean men. British Journal of Nutrition 2010; 104(8): 1241-1248. doi:10.1017/S0007114510001911
  32. Frid AH, Nilsson M, Holst JJ, Bjorck ME. Effect of whey on blood glucose and insulin responses to composite breakfast and lunch meals in type 2 diabetic subjects. American Society for Clinical Nutrition 2005; 82(1): 69-75.
  33. 33.0 33.1 O’Keefe JH, Gheewala NM, O’Keefe JO. Dietary Strategies for Improving Post-Prandial Glucose, Lipids, Inflammation, and Cardiovascular Health Journal of the American College of Cardiology 2008; 51(3): 249-255. doi:10.1016/j.jacc.2007.10.016.
  34. Petersen BL, Ward LS, Bastian ED, Jenkins AL, Campbell J, Vuksan V. A whey protein supplement decreases post-prandial glycemia. Nutrition Journal 2009; 8(47): doi: 10.1186/1475-2891-8-47