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Wafi AM, Alhazmi OA, Jathmi AJ, Otaif AA, Sharif MA, Ismael AI, Qadry EA, Shaikh AY, Alfaify FH, Jesudoss HJ, Salih S. Protein supplement intake by non-athlete gym attendees in Jazan region: misconceptions and gender differences. J Sports Med Phys Fitness 2024; 64:151-159. [PMID: 38093639 DOI: 10.23736/s0022-4707.23.15251-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
BACKGROUND Protein supplements (PSs) have gained widespread popularity among non-athlete gym attendees, who often perceive them as essential tools for muscle growth and recovery. However, misinformation surrounding PSs may lead to inappropriate use and negative health consequences. This study aimed to assess whether non-athlete gym attendees using PSs have greater misconceptions than non-users while also examining the prevalence of PS consumption and gender differences. METHODS A cross-sectional study of 387 participants in the Jazan region was conducted. Customers of 10 fitness centers were screened with a questionnaire comprising questions to measure PS misconceptions. Participants were divided into PS users and non-users. Data were analyzed using descriptive statistics and the Chi-square test to assess the associations between variables. An independent t-test was used to compare the PS Misconception Index Score between the two groups. RESULTS A total of 82.4% of non-athlete gym attendees consumed at least one PS. Our findings revealed a significant association between gender and PS utilization (P<0.001), with a higher proportion of females (90.8%) consuming PS than males (77.6%). PS users had a significantly lower PS Misconception Index Score than non-users (26.8 vs. 28.3; P=0.006), indicating that PS users had a higher number of misconceptions. The internet (41.37%) and coaches (gym instructors/trainers) (34.48%) were the most common sources of information about PSs, with muscle gain being the primary reason for consumption (82.75%). CONCLUSIONS PS consumption is highly prevalent among non-athlete gym attendees in the Jazan region, with many individuals having misconceptions about their benefits and potential risks. Targeted educational interventions are needed to promote evidence-based knowledge about PSs for gym attendees, as well as for coaches, given that they were among the primary sources of information on supplements.
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Affiliation(s)
- Ahmed M Wafi
- Physiology Department, Faculty of Medicine, Jazan University, Jazan, Saudi Arabia -
| | | | - Ali J Jathmi
- Faculty of Medicine, Jazan University, Jazan, Saudi Arabia
| | | | - Murad A Sharif
- Faculty of Medicine, Jazan University, Jazan, Saudi Arabia
| | - Ahmed I Ismael
- Faculty of Medicine, Jazan University, Jazan, Saudi Arabia
| | - Esam A Qadry
- Faculty of Medicine, Jazan University, Jazan, Saudi Arabia
| | - Ali Y Shaikh
- Faculty of Medicine, Jazan University, Jazan, Saudi Arabia
| | | | | | - Sarah Salih
- Department of Family and Community Medicine, Faculty of Medicine, Jazan University, Jazan, Saudi Arabia
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Kostopoulos N, Zacharakis E, Bolatoglou T, Kostopoulos P, Ktistakis I, Xirouchaki CE. Nutritional habits and knowledge in elite and professional basketball players. GAZZETTA MEDICA ITALIANA ARCHIVIO PER LE SCIENZE MEDICHE 2020. [DOI: 10.23736/s0393-3660.19.04068-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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3
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Antonio J, Candow DG, Forbes SC, Ormsbee MJ, Saracino PG, Roberts J. Effects of Dietary Protein on Body Composition in Exercising Individuals. Nutrients 2020; 12:E1890. [PMID: 32630466 PMCID: PMC7353221 DOI: 10.3390/nu12061890] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 06/17/2020] [Accepted: 06/19/2020] [Indexed: 12/26/2022] Open
Abstract
Protein is an important component of a healthy diet and appears to be integral to enhancing training adaptations in exercising individuals. The purpose of this narrative review is to provide an evidence-based assessment of the current literature examining increases in dietary protein intake above the recommended dietary allowance (RDA: 0.8 g/kg/d) in conjunction with chronic exercise on body composition (i.e., muscle, fat and bone). We also highlight acute and chronic pre-sleep protein studies as well as the influence of exercise timing on body composition. Overall, a high-protein diet appears to increase muscle accretion and fat loss and may have beneficial effects on bone when combined with exercise. Pre-sleep protein is a viable strategy to help achieve total daily protein goals. Importantly, there appears to be no deleterious effects from a high-protein diet on muscle, fat or bone in exercising individuals.
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Affiliation(s)
- Jose Antonio
- Department of Health and Human Performance, Nova Southeastern University, Davie, FL 33314, USA
| | - Darren G. Candow
- Faculty of Kinesiology and Health Studies, University of Regina, Regina, SK S4S0A2, Canada;
| | - Scott C. Forbes
- Faculty of Education, Department of Physical Education, Brandon University, Brandon, MB R7A6A9, Canada;
| | - Michael J. Ormsbee
- Department of Nutrition, Food & Exercise Sciences, Institute of Sports Sciences & Medicine, Florida State University, Tallahassee, FL 32313, USA; (M.J.O.); (P.G.S.)
- Discipline of Biokinetics, Exercise and Leisure Sciences, University of KwaZulu-Natal, Durban 4041, South Africa
| | - Patrick G. Saracino
- Department of Nutrition, Food & Exercise Sciences, Institute of Sports Sciences & Medicine, Florida State University, Tallahassee, FL 32313, USA; (M.J.O.); (P.G.S.)
| | - Justin Roberts
- Cambridge Centre for Sport and Exercise Sciences, Anglia Ruskin University, Cambridge CB11PT, UK;
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Affiliation(s)
- Peter W. R. Lemon
- School of Physical Education, Recreation and Dance, Applied Physiology Research Laboratory, Kent State University, Kent, Ohio 44242, USA
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Jäger R, Kerksick CM, Campbell BI, Cribb PJ, Wells SD, Skwiat TM, Purpura M, Ziegenfuss TN, Ferrando AA, Arent SM, Smith-Ryan AE, Stout JR, Arciero PJ, Ormsbee MJ, Taylor LW, Wilborn CD, Kalman DS, Kreider RB, Willoughby DS, Hoffman JR, Krzykowski JL, Antonio J. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr 2017; 14:20. [PMID: 28642676 PMCID: PMC5477153 DOI: 10.1186/s12970-017-0177-8] [Citation(s) in RCA: 326] [Impact Index Per Article: 46.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Accepted: 06/05/2017] [Indexed: 01/03/2023] Open
Abstract
The International Society of Sports Nutrition (ISSN) provides an objective and critical review related to the intake of protein for healthy, exercising individuals. Based on the current available literature, the position of the Society is as follows:An acute exercise stimulus, particularly resistance exercise, and protein ingestion both stimulate muscle protein synthesis (MPS) and are synergistic when protein consumption occurs before or after resistance exercise.For building muscle mass and for maintaining muscle mass through a positive muscle protein balance, an overall daily protein intake in the range of 1.4-2.0 g protein/kg body weight/day (g/kg/d) is sufficient for most exercising individuals, a value that falls in line within the Acceptable Macronutrient Distribution Range published by the Institute of Medicine for protein.Higher protein intakes (2.3-3.1 g/kg/d) may be needed to maximize the retention of lean body mass in resistance-trained subjects during hypocaloric periods.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 regarding the optimal protein intake per serving for athletes to maximize MPS 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.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 ideally be evenly distributed, every 3-4 h, across the day.The optimal time period during which to ingest protein is likely a matter of individual tolerance, since benefits are derived from pre- or post-workout ingestion; however, the anabolic effect of exercise is long-lasting (at least 24 h), but likely diminishes with increasing time post-exercise.While it is possible for physically active individuals to obtain their daily protein requirements through the consumption of whole foods, supplementation is a practical way of ensuring intake of adequate protein quality and quantity, while minimizing caloric intake, particularly for athletes who typically complete high volumes of training. Rapidly digested proteins that contain high proportions of essential amino acids (EAAs) and adequate leucine, are most effective in stimulating MPS. Different types and quality of protein can affect amino acid bioavailability following protein supplementation. Athletes should consider focusing on whole food sources of protein that contain all of the EAAs (i.e., it is the EAAs that are required to stimulate MPS). 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. Pre-sleep casein protein intake (30-40 g) provides increases in overnight MPS and metabolic rate without influencing lipolysis.
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Affiliation(s)
| | - Chad M. Kerksick
- Exercise and Performance Nutrition Laboratory, School of Health Sciences, Lindenwood University, St. Charles, MO USA
| | - Bill I. Campbell
- Performance & Physique Enhancement Laboratory, University of South Florida, Tampa, FL USA
| | - Paul J. Cribb
- Metabolic Precision Certifications, Queensland, Australia
| | | | | | | | | | - Arny A. Ferrando
- Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, AR USA
| | - Shawn M. Arent
- IFNH Center for Health & Human Performance, Department of Kinesiology & Health, Rutgers, the State University of New Jersey, New Brunswick, New Jersey USA
| | - Abbie E. Smith-Ryan
- Applied Physiology Laboratory, Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, NC USA
| | - Jeffrey R. Stout
- Institute of Exercise Physiology and Wellness, University of Central Florida, Orlando, FL USA
| | - Paul J. Arciero
- Human Nutrition and Metabolism Laboratory, Health and Exercise Sciences Department, Skidmore College, Saratoga Springs, NY 12866 USA
| | - Michael J. Ormsbee
- Department of Nutrition, Food and Exercise Sciences, Institute of Sport Sciences and Medicine, Florida State University, Tallahassee, USA
- Biokinetics, Exercise and Leisure Studies, University of KwaZulu-Natal, Durban, 4000 South Africa
| | - Lem W. Taylor
- Human Performance Laboratory, University of Mary Hardin-Baylor UMHB, Belton, TX 76513 USA
| | - Colin D. Wilborn
- Human Performance Laboratory, University of Mary Hardin-Baylor UMHB, Belton, TX 76513 USA
| | - Doug S. Kalman
- Department of Nutrition & Endocrinology, QPS, Miami, FL USA
| | - Richard B. Kreider
- Exercise & Sport Nutrition Lab, Human Clinical Research Facility, Department of Health & Kinesiology, Texas A&M University, College Station, TX USA
| | - Darryn S. Willoughby
- Exercise and Biochemical Nutrition Laboratory, Department of Health, Human Performance, and Recreation, Baylor University, Waco, TX USA
| | - Jay R. Hoffman
- Institute of Exercise Physiology and Wellness, University of Central Florida, Orlando, FL USA
| | | | - Jose Antonio
- Department of Health and Human Performance, Nova Southeastern University, Davie, FL USA
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Poortmans JR, Carpentier A. Protein metabolism and physical training: any need for amino acid supplementation? ACTA ACUST UNITED AC 2016. [DOI: 10.1186/s41110-016-0022-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Schröder S, Fischer A, Vock C, Böhme M, Schmelzer C, Döpner M, Hülsmann O, Döring F. Nutrition concepts for elite distance runners based on macronutrient and energy expenditure. J Athl Train 2009; 43:489-504. [PMID: 18833312 DOI: 10.4085/1062-6050-43.5.489] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
CONTEXT Elite distance runners (EDR) must optimize their nutrition to maintain their demanding training schedules. OBJECTIVE To develop a nutrition concept for EDR based on energy and macronutrient expenditures. DESIGN This theoretical study provides calculations for macronutrient and energy expenditures of EDR. Anthropometric and metabolic characteristics of EDR were assumed based on average real EDR. SETTING University of Kiel. PATIENTS OR OTHER PARTICIPANTS Three prototypic types of male EDR described in the literature as type I (TI; body mass = 72 kg, respiratory quotient = 0.9 at rest, fast-twitch muscle fibers = 60% to 70%), type II (TII; body mass = 67 kg, respiratory quotient = 0.82 at rest, fast-twitch muscle fibers = 50%), and type III (TIII; body mass = 60 kg, respiratory quotient = 0.75 at rest, fast-twitch muscle fibers = 30% to 40%). MAIN OUTCOME MEASURE(S) We calculated the macronutrient and energy expenditures of the 3 types of EDR according to body mass, respiratory quotient, and percentage of fast-twitch muscle fibers. RESULTS We found that the average energy expenditure was 3750 kcal . d(-1) for TI runners, 3463 kcal . d(-1) for TII runners, and 3079 kcal . d(-1) for TIII runners. The carbohydrate (CHO) expenditure reached an average value of 10.0 g . kg(-1) . d(-1) for TI runners, 8.0 g . kg(-1) . d(-1) for TII runners, and 4.7 g . kg(-1) . d(-1) for TIII runners. When the EDR accomplished running sessions at a pace >or=100% of maximum oxygen consumption, all types of runners had a CHO demand of about 10 g . kg(-1) . d(-1). The TI and TII runners need a CHO intake of 8 to 10 g . kg(-1) . d(-1). For the TIII runners, a CHO intake >6 g . kg(-1) . d(-1) is necessary during anaerobic training sessions. CONCLUSIONS Nutrition concepts must be differentiated for EDR according to metabolic and anthropometric characteristics of the runners and their special training emphases.
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Duellman MC, Lukaszuk JM, Prawitz AD, Brandenburg JP. Protein Supplement Users Among High School Athletes Have Misconceptions About Effectiveness. J Strength Cond Res 2008; 22:1124-9. [DOI: 10.1519/jsc.0b013e31817394b9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
AbstractThe use of nutritional supplements in sport is widespread and few serious athletes do not, at some stage in their career, succumb to the temptation to experiment with one or more nutritional supplements. Nutritional ergogenic aids are aimed primarily at enhancing performance (either by affecting energy metabolism or by an effect on the central nervous system), at increasing lean body mass or muscle mass by stimulation of protein synthesis and at reducing body fat content. Although not strictly ergogenic (i.e. capable of enhancing work performance), supplements aimed at increasing resistance to infection and improving general health are seen by athletes as important in reducing the interruptions to training that minor illness and infection can cause. Creatine is perhaps the most widely used supplement in sport at the moment. Supplementation can increase muscle creatine phosphate levels and, although not all published studies show positive results, there is much evidence that performance of short-term high-intensity exercise can be improved by supplementation. Ingestion of large doses of bicarbonate can enhance performance of exercise where metabolic acidosis may be a limiting factor, but there is a significant risk of adverse gastrointestinal side effects. Caffeine can also improve performance, in part by a stimulation of fatty acid mobilization and sparing of the body's limited carbohydrate stores, but also via direct effects on muscle and possibly by central nervous system effects on the perception of effort and fatigue. Carnitine plays an essential role in fatty acid oxidation in muscle but, although supplements are used by athletes, there is no good evidence of a beneficial effect of supplementation. None of these products contravenes the International Olympic Committee regulations on doping in sports, although caffeine is not permitted above a urine concentration of 12 mg/l. Supplementation is particularly prevalent among strength and power athletes, where an increase in muscle mass can benefit performance. Protein supplements have not been shown to be effective except in those rare cases where the dietary protein intake is otherwise inadequate. Individual amino acids, especially ornithine, arginine and glutamine, are also commonly used, but their benefit is not supported by documented evidence. Cr and hydroxymethylbutyrate are also used by strength athletes, but again there are no well-controlled studies to provide evidence of a beneficial effect. Athletes use a wide variety of supplements aimed at improving or maintaining general health and vitamin and mineral supplementation is widespread. There is a theoretical basis, and limited evidence, to support the use of antioxidant vitamins and glutamine during periods of intensive training, but further evidence is required before the use of these supplements can be recommended.
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10
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Maughan RJ, Shirreffs SM, Leiper JB. Errors in the estimation of hydration status from changes in body mass. J Sports Sci 2007; 25:797-804. [PMID: 17454547 DOI: 10.1080/02640410600875143] [Citation(s) in RCA: 163] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Hydration status is not easily measured, but acute changes in hydration status are often estimated from body mass change. Changes in body mass are also often used as a proxy measure for sweat losses. There are, however, several sources of error that may give rise to misleading results, and our aim in this paper is to quantify these potential errors. Respiratory water losses can be substantial during hard work in dry environments. Mass loss also results from substrate oxidation, but this generates water of oxidation which is added to the body water pool, thus dissociating changes in body mass and hydration status: fat oxidation actually results in a net gain in body mass as the mass of carbon dioxide generated is less than the mass of oxygen consumed. Water stored with muscle glycogen is presumed to be made available as endogenous carbohydrate stores are oxidized. Fluid ingestion and sweat loss complicate the picture by altering body water distribution. Loss of hypotonic sweat results in increased osmolality of body fluids. Urine and faecal losses can be measured easily, but changes in the water content of the bladder and the gastrointestinal tract cannot. Body mass change is not always a reliable measure of changes in hydration status and substantial loss of mass may occur without an effective net negative fluid balance.
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Affiliation(s)
- Ronald J Maughan
- School of Sport and Exercise Sciences, Loughborough University, Loughborough, UK.
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11
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Abstract
The main determinants of an athlete's protein needs are their training regime and habitual nutrient intake. Most athletes ingest sufficient protein in their habitual diet. Additional protein will confer only a minimal, albeit arguably important, additional advantage. Given sufficient energy intake, lean body mass can be maintained within a wide range of protein intakes. Since there is limited evidence for harmful effects of a high protein intake and there is a metabolic rationale for the efficacy of an increase in protein, if muscle hypertrophy is the goal, a higher protein intake within the context of an athlete's overall dietary requirements may be beneficial. However, there are few convincing outcome data to indicate that the ingestion of a high amount of protein (2-3 g x kg(-1) BW x day(-1), where BW = body weight) is necessary. Current literature suggests that it may be too simplistic to rely on recommendations of a particular amount of protein per day. Acute studies suggest that for any given amount of protein, the metabolic response is dependent on other factors, including the timing of ingestion in relation to exercise and/or other nutrients, the composition of ingested amino acids and the type of protein.
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Affiliation(s)
- Kevin D Tipton
- Department of Surgery, University of Texas Medical Branch, Shriner's Hospital for Children, 815 Market Street, Galveston, TX 77550, USA.
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Gillies EM, Putman CT, Bell GJ. The effect of varying the time of concentric and eccentric muscle actions during resistance training on skeletal muscle adaptations in women. Eur J Appl Physiol 2006; 97:443-53. [PMID: 16685548 DOI: 10.1007/s00421-006-0192-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/22/2006] [Indexed: 10/24/2022]
Abstract
This study investigated the effect of manipulating the time to complete both the concentric (CON) and eccentric (ECC) muscle actions during resistance training on strength, skeletal muscle properties and cortisol in women. Twenty-eight women (mean +/- SE age = 24.3 +/- 1.1 year) with strength training experience completed three training sessions per week for 9 weeks. Two sets of four lower body exercises (leg press, parallel squat, knee extension and knee flexion) were completed using 6-8 RM intensity. The long CON (LC) group performed the CON action for 6 s and the ECC action for 2 s, while the long ECC (LE) group completed the CON and ECC phases for 2 and 6 s, respectively. Both groups experienced significant increases in leg press CON only, ECC only and combined ECC and CON maximal strength (1 RM). Immunohistochemical analyses demonstrated that both types I and IIA vastus lateralis fibre areas significantly increased following LC training while only type I fibre area increased following LE training. There was a decrease in MHCIId(x) with a concomitant increase in MHCIIa (P < 0.05) in both groups. Twenty-four hour urinary cortisol significantly increased after LC training only. It was concluded that LC resistance training was more effective than LE for increasing both types I and IIA fibre area and cortisol when time under tension and intensity of muscle actions were matched between the two modes of resistance training in young healthy women.
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Affiliation(s)
- Ellen M Gillies
- Exercise Biochemistry Laboratory, Faculty of Physical Education and Recreation, E424 Van Vliet Centre, University of Alberta, Edmonton, AB, Canada T6G 2H9
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13
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Abstract
The development of performance in competition is achieved through a training process that is designed to induce automation of motor skills and enhance structural and metabolic functions. Training also promotes self-confidence and a tolerance for higher training levels and competition. In general, there are two broad categories of athletes that perform at the highest level: (i) the genetically talented (the thoroughbred); and (ii) those with a highly developed work ethic (the workhorse) with a system of training guiding their effort. The dynamics of training involve the manipulation of the training load through the variables: intensity, duration and frequency. In addition, sport activities are a combination of strength, speed and endurance executed in a coordinated and efficient manner with the development of sport-specific characteristics. Short- and long-term planning (periodisation) requires alternating periods of training load with recovery for avoiding excessive fatigue that may lead to overtraining. Overtraining is long-lasting performance incompetence due to an imbalance of training load, competition, non-training stressors and recovery. Furthermore, annual plans are normally constructed in macro-, meso- and microcycles around the competitive phases with the objective of improving performance for a peak at a predetermined time. Finally, at competition time, optimal performance requires a healthy body, and integration of not only the physiological elements but also the psychological, technical and tactical components.
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Affiliation(s)
- David J Smith
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Alberta, Canada T2N 2N4.
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Abstract
Nutritional interventions have the potential to influence the outcome of athletic competition where opponents are closely matched. Sound dietary habits can also influence the adaptations that occur in response to training. This article summarizes some of the strategies that the athlete can use to enhance performance.
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Affiliation(s)
- Ron Maughan
- Department of Biomedical Sciences, University Medical School, Aberdeen AB9 2ZD
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15
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Abstract
When talented, motivated and highly trained athletes meet for competition the margin between victory and defeat is usually small. When everything else is equal, nutrition can make the difference between winning and losing. Although the primary concern of many athletes is to supplement the diet with protein, vitamins and minerals, and a range of more exotic compounds, key dietary issues are often neglected. Athletes must establish their nutritional goals, and must also be able to translate them into dietary strategies that will meet these goals. Athletes are often concerned with dietary manipulations in the period around competition, but the main role of nutrition may be to support consistent intensive training which will lead to improved performance. Meeting energy demand and maintaining body mass and body fat at appropriate levels are key goals. An adequate intake of carbohydrate is crucial for maintaining muscle glycogen stores during hard training, but the types of food and the timing of intake are also important. Protein ingestion may stimulate muscle protein synthesis in the post-exercise period, promoting the process of adaptation in the muscles. Restoration of fluid and electrolyte balance after exercise is essential. If energy intake is high and a varied diet is consumed, supplementation of the diet with vitamins and minerals is not warranted, unless a specific deficiency is identified. Specific strategies before competition may be necessary, but this requirement depends on the demands of the sport. Generally, it is important to ensure high pre-competition glycogen stores and to maintain fluid balance. There is limited evidence to support the use of dietary supplements, but some, including perhaps creatine and caffeine, may be beneficial.
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Abstract
The nutritional requirements of the training and competition programmes of elite endurance cyclists are challenging. Notwithstanding the limitations of dietary survey techniques, studies of high-level male road cyclists provide important information about nutrient intake and food practices during training and major stage races. Typically, male cyclists undertaking intensive training programmes report a high energy intake (> or = 250 kJ/kg/day) and carbohydrate (CHO) intakes of 8 to 11 g/kg/day. Intakes of protein and micronutrients are likely to meet Recommended Dietary Intake levels, because of high energy intakes. Data on female cyclists are scarce. Stage racing poses an increased requirement for energy and CHO, with daily energy expenditure often exceeding 25 MJ. This must be achieved in the face of practical constraints on the time available for eating, and the suppression of appetite after exhausting exercise. However, studies show that male cyclists riding for professional teams appear to meet these challenges, with the assistance of their medical/scientific support crews. Current dietary practices during cycle tours appear to favour greater reliance on pre-stage intake and post-stage recovery meals to achieve nutritional goals. Recent reports suggest that current riding tactics interfere with previous practices of consuming substantial amounts of fluid and CHO while cycling. Further study is needed to confirm these practices, and to investigate whether these or other dietary strategies produce optimal cycling performance. Other issues that should receive attention include dietary practices of female cyclists, beliefs and practices regarding bodyweight control among cyclists, and the use of supplements and sports foods.
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Affiliation(s)
- L M Burke
- Department of Sports Nutrition, Australian Institute of Sport, Belconnen, Australian Capital Territory.
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18
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Smith DJ, Norris SR. Changes in glutamine and glutamate concentrations for tracking training tolerance. Med Sci Sports Exerc 2000; 32:684-9. [PMID: 10731013 DOI: 10.1097/00005768-200003000-00020] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE The purpose was to monitor high-performance athletes throughout training macrocycles and competitions and examine the changes in plasma glutamine (Gm) and glutamate (Ga) concentrations in order to develop a model of tolerance to training. METHODS Plasma glutamine and glutamate concentrations of 52 National team athletes (31 male and 21 female) divided into male and female groups of speed skating, swimming, and cross-country skiing were measured in an early season rested condition to determine highest Gm and lowest Ga concentrations and over 2-4 macrocycles, which included heavy training to establish lowest Gm and highest Ga concentrations. RESULTS In the rested condition, there were no differences within and between the male and female groups, excluding five athletes (OTA) who became overtrained in heavy training. The mean (+/-SD) Gm concentration was 585 +/- 54 micromol x L(-1), Ga concentration 101 +/- 16 micromol x L(-1), and Gm/Ga ratio 5.88 +/- 0.84 micromol x L(-1). The OTA had a significantly higher Ga concentration of 128 +/- 16 micromol x L(-1) and lower Gm/Ga ratio of 4.43 +/- 0.49 micromol x L(-1) than all the other groups. In heavy training, there was a significant decrease (P < 0.05) in Gm concentration to 522 +/- 53 micromol x L(-1), significant increase in Ga concentration to 128 +/- 19 micromol x L(-1) and significant decrease in Gm/Ga ratio to 4.15 +/- 0.57 micromol x L(-1). The OTA Gm concentration of 488 +/- 31 micromol x L(-1) was significant lower than only the male speed skating and swimming groups. However, the Ga concentration of 171 +/- 17 micromol x L(-1) and Gm/Ga ratio of 2.88 +/- 0.27 micromol x L(-1) were significantly higher and lower respectively than all other groups. CONCLUSIONS Based on the changes in Gm and Ga concentration under different training conditions, we propose an athlete tolerance to training model where glutamine concentration reflects tolerance to volume of work and glutamate concentration reflects tolerance to high intensity training. We suggest that the Gm/Ga ratio may globally represent overall tolerance to training.
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Affiliation(s)
- D J Smith
- Human Performance Laboratory, Faculty of Kinesiology, The University of Calgary and The National Sports Centre-Calgary, Alberta, Canada.
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19
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Maughan RJ. Supplements in news: creatine. NUTR BULL 1999. [DOI: 10.1111/j.1467-3010.1999.tb00900.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Maughan R, Burke L. L'alimentation du footballeur au cours de l'entraînement et de la compétition. Sci Sports 1999. [DOI: 10.1016/s0765-1597(00)88241-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
Este estudo foi realizado no primeiro semestre de 1996 e teve como alvo os freqüentadores das academias da cidade de Belém (PA). Além de pesquisa bibliográfica referente ao metabolismo energético e protéico, necessidades nutricionais de desportistas e suplementação com proteínas e aminoácidos, foi realizada uma pesquisa de campo com o objetivo de traçar o perfil de utilização de suplementos nutricionais, com ênfase em produtos a base de proteínas e aminoácidos, por sexo, idade e tempo de prática de atividade física. A pesquisa de campo envolveu uma amostra de 18 academias e 388 entrevistados, dos quais 103 (27%) faziam uso de algum tipo de suplemento, sendo que 45 destes (44%) utilizavam repositores protéicos. Das justificativas para opção de uso desses suplementos, destacou-se a "indicação profissional" que comparada ao quadro técnico existente nessas unidades, em que apenas 4 das 18 academias pesquisadas apresentavam nutricionistas ou médicos, indica que a utilização desses produtos por parte dos praticantes de atividades físicas está sendo indevida.
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22
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Saris WH, Asp NG, Björck I, Blaak E, Bornet F, Brouns F, Frayn KN, Fürst P, Riccardi G, Roberfroid M, Vogel M. Functional food science and substrate metabolism. Br J Nutr 1998; 80 Suppl 1:S47-75. [PMID: 9849354 DOI: 10.1079/bjn19980105] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The present review addresses the role of food constituents in the aetiology of metabolic conditions and chronic diseases, mostly related to energy metabolism and substrate regulation, such as obesity and non-insulin-dependent diabetes mellitus. Second, attention is paid to malnutrition, a major cause of mortality and morbidity in developing countries, which may be a cause of concern in Europe because of the increasing number of elderly people in the population. Finally, the role of diet during exercise, a condition of enormous substrate demands, is evaluated. Based on a critical evaluation of the existing knowledge in the literature, implications for future research in relation to functional foods are discussed.
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Affiliation(s)
- W H Saris
- Department of Human Biology, Maastricht University, The Netherlands.
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23
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Even PC, Rieth N, Roseau S, Larue-Achagiotis C. Substrate oxidation during exercise in the rat cannot fully account for training-induced changes in macronutrients selection. Metabolism 1998; 47:777-82. [PMID: 9667220 DOI: 10.1016/s0026-0495(98)90111-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
This study investigated spontaneous dietary adaptation to regular exercise in relation to substrate oxidation measured during exercise. Male Wistar rats were offered permanent access to the three sources of macronutrients supplemented with minerals and vitamins. The rats remained sedentary or were trained daily during 3 weeks at moderate intensity (20 m x min(-1), 2 hours). Body weight, total caloric intake, and macronutrients selection were recorded throughout the experiment. Energy expenditure and substrate oxidation were measured before, during, and after an exercise identical for trained and untrained rats (10 m x min(-1) 1 hour). Training reduced body weight gain (2.27 v 5.57 g x day(-1)), increased protein intake (52.6% v 39.2%), and decreased carbohydrate intake (21.3% v 39.5%). Basal and running energy expenditure, as well as glucose and lipid oxidation, remained essentially comparable in trained and untrained rats. The relative contribution of glucose oxidation (Gox) to total energy expenditure decreased during exercise (52.2%, average of all rats) relative to before exercise (60.8%). Gox during exercise was positively correlated with resting Gox before exercise, showing that preexercise substrate oxidation was a strong determinant of running substrate oxidation. However, the slope was smaller for the trained than for the untrained rats, showing that exercise increases Gox less in trained rats than in untrained ones. We conclude from this study that, since food selection but not substrate oxidation changed following training, food intake adapted to substrate requirements induced by regular training and not the contrary. However, large differences remained between the mixture ingested, in which lipids accounted for only 26% of the energy, and the mixture oxidized during exercise, in which lipids accounted for 50.7% of the substrate oxidized. Such a difference may be related to metabolic requirements during the rest of the day and/or to the distribution of macronutrients intake relative to exercise. This question deserves further investigation with recording of macronutrients selection, energy expenditure, and substrate oxidation over 24 hours.
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Affiliation(s)
- P C Even
- Laboratoire de Nutrition Humaine et Physiologie Intestinale, Institut National Recherche Agronomique-Institut National Agronomique Paris Grignon, France
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24
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Affiliation(s)
- C Williams
- Human Muscle Metabolism Research Group, Loughborough University, UK.
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25
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26
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Abstract
Athletes should eat a well-balanced diet made up of a wide variety of foods in sufficient quantity to cover their daily energy expenditures. Carbohydrate-containing foods should provide approximately 60-70% of their daily energy intake, protein approximately 12-15%, with the remainder being provided by fat. The higher carbohydrate intakes, however, are only recommended during preparation for, and immediate recovery from, heavy training and competition. Adopting nutritional strategies to increase muscle and liver glycogen stores before, during and after exercise can improve performance. The protein requirements of most athletes are fulfilled when their daily intake is between 1.2 and 1.7 g per kg body mass. This amount of protein is provided by a diet which covers the athlete's daily energy expenditure. Although fat metabolism contributes to energy production during exercise, and the amount increases with endurance training, there is no evidence to suggest that athletes should increase their fat intake as a means of improving their performance.
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Affiliation(s)
- C Williams
- Department of Physical Education, Sports Science and Recreation Management, Loughborough University of Technology, UK
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27
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Affiliation(s)
- R J Maughan
- University Medical School, Foresterhill, Aberdeen
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28
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Wootton S. Sports nutrition--theory into practice. JOURNAL OF THE ROYAL SOCIETY OF HEALTH 1994; 114:41-3. [PMID: 8164245 DOI: 10.1177/146642409411400109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- S Wootton
- Department of Human Nutrition, University of Southampton
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29
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Abstract
Inadequate diet inhibits optimal performance in otherwise well-trained athletes. Controversy exists regarding specific dietary requirements, particularly in the areas of protein and vitamin/mineral supplementation. This article reviews energy substrate utilization, provides an overview of nutrient requirements during exercise, discusses ergogenic aids, and where possible, makes specific dietary recommendations for athletes.
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Affiliation(s)
- C K Probart
- Department of Nutrition, Pennsylvania State University, University Park
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30
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Position of the American Dietetic Association and the Canadian Dietetic Association: nutrition for physical fitness and athletic performance for adults. JOURNAL OF THE AMERICAN DIETETIC ASSOCIATION 1993; 93:691-6. [PMID: 8509598 DOI: 10.1016/0002-8223(93)91681-f] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The importance of diet and healthful food choices in optimizing health status, fitness levels, and athletic performance has been recognized by both participants and professionals. There continues to be a need for the interpretation of new research findings in this fast-growing discipline and for the dissemination of nutrition information and training techniques for a broad spectrum of individuals involved in various forms of physical activity. The registered dietitian who has specialized in exercise physiology and sports nutrition has the knowledge and counseling skills to act as the provider of this nutrition information. Additional information may be obtained in the Sports Nutrition Manual, 2nd edition, published by The American Dietetic Association and the Sports and Cardiovascular Nutrition dietetic practice group as well as in Sport Nutrition for the Athletes of Canada, published by the Sport Nutrition Advisory Committee of the Sports Medicine and Science Council of Canada.
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31
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Etude du métabolisme des protéines au cours des sports de force. NUTR CLIN METAB 1993. [DOI: 10.1016/s0985-0562(05)80281-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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