INTRODUCTION AND CURRENT PROTEIN RECOMMENDATIONS FOR STRENGTH BASED ATHLETES
Controversy surrounds the timing of ingesting protein recommendations (from food or supplements) following resistance training. Therefore, the aim of this review is to advise coaches on practical recommendations for optimal protein intake in resistance trained athletes and explore the data surrounding consumption and timing of protein post exercise.
Ausport.gov.au (2015) recommends more protein for athletes of a younger resistance training age. Athletes in the early stages of training should have 1.5-1.7g/kg. When the athletes reaches a “steady state” it is suggested that protein intake decrease to 1.0-1.2 g/kg per day. Ausport.gov.au (2015) advocates lowering protein because when athletes have adapted to the total amount of work or volume (reps x sets x weight lifted) they’re able to recover quicker than a younger athlete of a lower training age.
HOW MUCH PROTEIN ARE ATHLETES CONSUMING?
Athlete’s protein consumption varies depending on the sport they participate in. For instance, athletes concerned with increasing muscle magnitude and power may increase their protein intake. In contrast, athletes who are more inclined to participate in endurance sports are more likely to eat carbohydrate dense food in order to fuel their training needs and skimp on the protein as protein has a satiating effect and might displace other foods in the diet (Ausport.gov.au, 2015). It would appear that amino acids are a popular supplement amongst high level athletes (Apostolidis et al., 2013). This finding suggests that athletes strive to ingest high levels of protein to possibly facilitate athletic performance. This statement doesn’t go without any weight either. For instance, Breitbach et al (2011) found that that athletes consume 2.0g/kg/d of protein. Further, athletes thought they needed up to 2.4 g/kg/d. Another interesting finding was that 67% of athletes didn’t know how much protein they needed or were consuming. Future education interventions should strive to educate athletes on how much protein they need and how to track and count their macronutrient intakes.
IS PRE AND POST WORKOUT NUTRITION REALLY THAT IMPORTANT?
There is much controversy surrounding pre and post workout nutrition amongst the food and fitness community, and resistance training athletes. Therefore, this section of the paper aims to critique currently literature surrounding pre, intra and post workout nutrition in an attempt to provide practical recommendations for coaches, nutritionists, and sports dieticians in regards to protein intake for their athletes. For a much more extensive review of the literature, more specific to the nutrient timing please see Aragon and Schoenfeld, (2013)
19 untrained women consumed 18.3 g of essential amino acids or cellulose at an equal dose which they took 20 minutes before and after training. A 3 day resistance training intervention was undertaken for a total of 6 weeks. Body composition was measured by DXA scans which have been considered the gold standard of measuring body composition (Whiteford et al., 2010). Researchers found that there was no significant difference between the placebo group and the group consuming essential amino acids 20 minutes before and after resistance training (Antonio et al., 2000). A limitation of this study was that the women participating in the resistance training program were untrained. Untrained individuals experience rapid gains in lean muscle when they first start a resistance training regimen. It is possible that individuals who have been training longer may have experienced statistically significant gains with a greater focus on meal timing. However, the results still suggest that meal timing is irrelevant in untrained women whose goal is to improve body composition through resistance training. Similarly, protein timing doesn’t appear to be that important in elderly men either. 17 untrained elderly men consumed 12 g of essential amino acids and 72 g of fructose and dextrose as soon as they finished exercise for 12 weeks. There was no significant difference between groups in both 1RM bench press and increases in muscle cross sectional area (Godard, Williamson and Trappe, 2002). This study was limited by the fact that participants were “elderly men.” Elderly individuals have reduced levels of muscle protein synthesis (Churchward-Venne & Phillips, 2014). Therefore, this study may have been restricted by the fact that the participants couldn’t gain as much muscle as younger trainees and thus can’t be generalised to more youthful training populations.
But what about younger men? A study by Rankin et al., (2004) found that 13 young men who drank chocolate milk after resistance training (0.21g/kg/protein) or a carbohydrate electrolyte drinks saw no significant difference in 1RM strength and a reduction in fat mass, mean mass gain or change in circumference. Similarly Vieillevoye et al., (2010) found that there was no significant difference between muscle strength and size in groups who consumed 15 g of essential amino acids and 15 g of saccharose 30 g saccharose with breakfast and after exercise. This study was limited by the fact that the trainees were beginners. Beginners gain unquestionable amounts of fat free mass upon initiation of a resistance training program. Consequently, results may have been similar between both groups because newbie lifters can gain lots of muscle by undertaking in just about any resistance training intervention. However, the question still lies in whether protein timing is important in well trained young men who supplement protein close too or right after exercise.
Hoffman et al., (2009) conducted research on 33 well trained young men who consumed 42 g of protein and 2 g of carbohydrates either right before or right after exercise. The control group consumed the same amount of protein and carbohydrates later in the night and earlier in the morning. There was no significant difference between increases in squat and bench press strength, body mass or gains in fat free mass. This study might be limited in the fact that participants were “trained” subjects. Beginners to resistance training can gain a lot of muscle very quickly. The opposite is true for athletes who have been lifting weights for an extended period of time. Nevertheless, if coaches are really looking for that extra edge Norton and Wilson, (n.d.) suggest that 3 g of leucine per meal is needed to maximise the muscle protein synthesis response. The muscle protein synthesis response only lasts 3 hours. Therefore, it might be beneficial to consume several meals throughout the day containing 3 g of leucine.
NEGATIVE SIDE EFFECTS ASSOCIATED WITH TOO MUCH PROTEIN
It’s unlikely that an intake of protein below 2g/kg/day is going to cause athletes any harm in the short term. However, it’s important to consider that there is limited research to suggest that long term protein intake is safe or not safe (Ausport.gov.au, 2015).
There may be a correlation between heart disease and increased protein intake. High protein diets are generally high in saturated fats due to the inclusion of certain high fat meats (Kelemen, 2005). However, correlation doesn’t always equal causation and it’s therefore unclear whether the protein or saturated fat causes or contributes to the development of heart disease. It may be that the high fat content of the meat increases overall energy intake leading to overweight and obesity thereby increasing risk of heart disease.
Increases in protein intake may also shift the ratio of calcium and protein thereby contributing to the excretion of calcium. This may cause adult bone loss or osteoporosis (Whitney et al.). However, not all the research is in favour of protein contributing to poor bone health. It may depend on what type and/or form of the protein consumed. For instance Spencer et al., (1983) suggests that when the protein comes from meat it doesn’t alter calcium metabolism. This is significant because it gives us insight in to whether or not it’s in fact the protein that causes increases in calcium excretion.
PUTTING THE INFORMATION INTO PRACTICE – WHAT DOES THIS MEAN FOR THE STRENGTH TRAINING COMMUNITY?
Protein is needed for the maintenance of growth and muscle mass which may thereby increase athletic performance in the weight room (Jones et al., 2008). Protein recommendations range from as little as 1g/kg/d to 4.4g/kg/d for both gains and maintenance in lean tissue (Antonio et al., 2014; Ausport.gov.au, 2015). The bulk of evidence suggests that consuming more than 4g/kg/d is far too high and that 1g/kg is far too low (Ausport.gov.au, 2015; Lemon et al., 1992; Lemon, 2000; Phillips, 2006). Based on the body of evidence protein recommendations for strength training athletes should be between 1.5-2.5 g/kg of bodyweight depending on total daily energy consumption in order to maximise muscle strength and size. Furthermore, it is evident that meal timing interventions where athletes over-stress about the amount of protein that they consume following a workout is irrelevant in the face of a solid resistance training program and total protein intake for the day. Diet interventions should be made as effortless and as easily manageable as possible to ensure consistency amongst sports personal and high retention rates. For strength training athletes, the number one goal should be consuming a high protein diet and meeting daily protein requirements.
REFERENCES
Antonio, J., Peacock, C., Ellerbroek, A., Fromhoff, B. and Silver, T. (2014). The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals. J Int Soc Sports Nutr, 11(1), p.19.
Antonio, J., Sanders, M., Ehler, L., Uelmen, J., Raether, J. and Stout, J. (2000). Effects of exercise training and amino-acid supplementation on body composition and physical performance in untrained women. Nutrition, 16(11-12), pp.1043-1046.
Aragon, A. and Schoenfeld, B. (2013). Nutrient timing revisited: is there a post-exercise anabolic window?. J Int Soc Sports Nutr, 10(1), p.5.
Ausport.gov.au, (2015). Protein : AIS : Australian Sports Commission. [online] Available at: http://www.ausport.gov.au/ais/nutrition/factsheets/basics/protein_-_how_much [Accessed 11 Mar. 2015].
Churchward-Venne, T, Breen, L, & Phillips, S 2014, ‘Alterations in human muscle protein metabolism with aging: Protein and exercise as countermeasures to offset sarcopenia’, Biofactors, 40, 2, pp. 199-205, Academic Search Complete, EBSCOhost, viewed 26 March 2015.
Frost, D, Cronin, J, & Newton, R 2010, ‘A Biomechanical Evaluation of Resistance: Fundamental Concepts for Training and Sports Performance’, Sports Medicine, 40, 4, pp. 303-326, SPORTDiscus with Full Text, EBSCOhost, viewed 26 March 2015
Fox, E, McDaniel, J, Breitbach, A, & Weiss, E 2011, ‘Perceived protein needs and measured protein intake in collegiate male athletes: an observational study’, Journal Of The International Society Of Sports Nutrition, 8, 1, pp. 9-14, SPORTDiscus with Full Text, EBSCOhost, viewed 18 March 2015.
GODARD, M., WILLIAMSON, D. and TRAPPE, S. (2002). Oral amino-acid provision does not affect muscle strength or size gains in older men. Medicine & Science in Sports & Exercise, 34(7), pp.1126-1131.
Giannopoulou, I, Noutsos, K, Apostolidis, N, Bayios, I, & Nassis, G 2013, ‘Performance Level Affects the Dietary Supplement Intake of Both Individual and Team Sports Athletes’, Journal Of Sports Science & Medicine, 12, 1, pp. 190-196, SPORTDiscus with Full Text, EBSCOhost, viewed 18 March 2015.
Hoffman, J., Ratamess, N., Tranchina, C., Rashti, S., Kang, J. and Faigenbaum, A. (2009). Effect Of Protein Supplement Timing On Strength, Power And Body Compositional Changes In Resistance-trained Men. Medicine & Science in Sports & Exercise, 41(Supplement 1), p.303.
Jones, E., Bishop, P., Woods, A. and Green, J. (2008). Cross-Sectional Area and Muscular Strength.Sports Medicine, 38(12), pp.987-994.
Kelemen, L. (2005). Associations of Dietary Protein with Disease and Mortality in a Prospective Study of Postmenopausal Women. American Journal of Epidemiology, 161(3), pp.239-249.
Lemon, P. (2000). Beyond the Zone: Protein Needs of Active Individuals. Journal of the American College of Nutrition, 19(sup5), pp.513S-521S.
Lemon, Tarnopolsky, MacDougall, and Atkinson, (1992). Protein requirements and muscle mass/strength changes during intensive training in novice bodybuilders. Journal of Applied Physiology, [online] 2(73), pp.767-765. Available at: http://www.ncbi.nlm.nih.gov/pubmed/1400008.
Norton, L. and Wilson, G. (n.d.). Optimal protein intake to maximize muscle protein synthesis Examinations of optimal meal protein intake and frequency for athletes. . Division of Nutritional Sciences, University of Illinois, pp.54-57.
Phillips, S. (2006). Dietary protein for athletes: from requirements to metabolic advantage. Appl. Physiol. Nutr. Metab., 31(6), pp.647-654.
Rankin, J., Goldman, L., Puglisi, M., Nickols-Richardson, S., Earthman, C. and Gwazdauskas, F. (2004). Effect of Post-Exercise Supplement Consumption on Adaptations to Resistance Training.Journal of the American College of Nutrition, 23(4), pp.322-330.
Spencer, H., Kramer, L., DeBartolo, M., Norris, C. and Osis, D. (1983). Further studies of the effect of a high protein diet as meat on calcium metabolism. The American Journal of Clinical Nutrition, pp.924-929.
Vieillevoye, S., Poortmans, J., Duchateau, J. and Carpentier, A. (2010). Effects of a combined essential amino acids/carbohydrate supplementation on muscle mass, architecture and maximal strength following heavy-load training. Eur J Appl Physiol, 110(3), pp.479-488.
Whiteford, J., Ackland, T., Dhaliwal, S., James, A., Woodhouse, J., Price, R., Prince, R. and Kerr, D. (2010). Effects of a 1-year randomized controlled trial of resistance training on lower limb bone and muscle structure and function in older men. Osteoporos Int, 21(9), pp.1529-1536.
Whitney, E., Cameron-Smith, D., Crowe, T., Walsh, A. and Rady Rolfes, S. (n.d.). Understanding nutrition.