How Protein Effects Athletes and Exercise

Recently I was doing research for a presentation. It was for one of my Nutrition classes, and I stumbled upon some interesting research. We hear all the time about athletes needing protein and taking supplements, but you hardly ever hear about the research. 

Well I am here to tell you how protein is important for athletes.

Every athlete is different and every sport is different. Each of these require different nutritional needs as well as their physical training needs. The changes that athletes aim to make in their bodies by doing exercise can be amplified or reduced depending on their nutrition.

Basically if you are eating unhealthy it can deter or diminish what you you are trying to accomplish physically. If you eat healthy and to the needs of your exercise regime you can increase your physical accomplishments. Especially when compared to utilizing a normal diet. 

Nutrition has a major impact on how well our body responds to the exercises we put it through. And the quality and quantity of our nutrition pre- and post-workout affect our ability to respond to said training. 

Effects of Protein on Exercise Performance

Most of the scientific research investigating the effects of protein intake on exercise performance has focused on supplemental protein intake. 

In a broad perspective, the dependent measures of these studies are categorized into two domains: 

• 􏰀  Endurance exercise performance 
• 􏰀  Resistance exercise performance (increases in maximal strength)
  

Protein and Endurance Exercise Performance

Dietary protein is not a preferred energy source for endurance athletes. Although more data is needed, it is shown that increasing protein intakes above recommended levels does not enhance endurance performance. Few studies have investigated the effects of prolonged periods (one week or more) of dietary protein effects on endurance performance. The data shows that adding protein to a carbohydrate beverage/gel during exhaustive endurance exercise suppresses markers of muscle damage (creatine kinase) 12 to 24 h post-exercise. As well as decreases the endurance athletes’ feelings of muscular soreness.

• Endurance athletes should focus on achieving adequate carbohydrate intake to promote optimal performance; the addition of protein may help to offset muscle damage and promote recovery.

Protein and Resistance Exercise Performance

The extent to which protein supplementation, used with resistance training, enhances maximal strength is dependent upon many factors, including:

•  Resistance-training program variables (such as intensity, volume, and progression) 
• Length of the resistance-training program/ intervention
• Training status of the participants engaging in the resistance-training program 
• Energy intake in the diet
• Quality and quantity of protein intake (with an emphasis on leucine content of the protein)
• Co-ingestion of additional dietary ingredients that may favorably impact strength (e.g. creatine, HMB) 

There are several conflicting studies on whether or not protein helps aid in strength for resistance exercise programs. But there are some general recommendations and findings among most of these studies. Greater protein intakes that are achieved from both dietary and supplemental sources have provide an advantage. One Study found found that protein supplementation with resistance training resulted in a 13.5 kg increase (95%) in lower-body strength when compared to changes seen when a placebo was provided. 

A similar conclusion was also found in another study done on untrained participants. Protein supplementation has very little benefit on strength during the initial weeks of a resistance training program. As duration, frequency and volume of resistance training increased, protein supplementation favorably impacted skeletal muscle hypertrophy and strength. 

• For building muscle mass and for maintaining muscle mass through a diet, a daily protein intake in the range of 1.4–2.0 g protein/kg body weight/day.
• Higher protein intakes (2.3–3.1 g/kg/d) are needed to maximize the retention of lean body mass in resistance-trained subjects during low caloric periods.

Protein Effects on Body Composition

Overall, it has been found that increasing dietary protein boost adaptations in body composition by using fat-free mass growth when combined with a high energy diet and a heavy resistance training program. It also aids the loss of fat mass when higher intakes of daily protein are combined with an exercise program and a high energy diet. 

• There is novel evidence that suggests higher protein intakes (>3.0 g/kg/d) may have positive effects on body composition in resistance-trained individuals (i.e., promote loss of fat mass). 

Recommendations on Protein for Athletes

Recommendations for protein intake for athletes to maximize muscle protein synthesis are mixed and are dependent upon age and recent resistance exercise stimuli. General recommendations are 0.25 g of a high-quality protein per kg of body weight, or an absolute dose of 20–40 g per serving.

• Acute protein doses should strive to contain 700–3000 mg of leucine and/or a higher relative leucine content. In addition to a balanced array of the essential amino acids (EAAs).
• These protein doses should be evenly distributed, every 3–4 h, across the day.
• The anabolic effect of exercise is long-lasting (at least 24 h), but likely diminishes with increasing time post-exercise.
• It is possible for physically active individuals to obtain their daily protein requirements through the consumption of whole foods. Supplementation is a way of ensuring intake of adequate protein quality and quantity, while minimizing caloric intake. This particularly works for athletes who typically complete high volumes of training.
• Rapidly digested proteins that contain high proportions of essential amino acids and adequate leucine, are most effective in stimulating MPS.
• Athletes should focus on whole food sources of protein that contain all of the EAAs.
• Pre-sleep casein protein intake (30–40 g) provides increases in overnight MPS and metabolic rate without influencing lipolysis.

REF: Journal of the International Society of Sports Nutrition, mainly the article; International Society of Sports Nutrition Position Stand: protein and exercise (2017).