Athletes utilise numerous strategies to reduce body weight or body fat prior to competition. The ... more Athletes utilise numerous strategies to reduce body weight or body fat prior to competition. The traditional approach requires continuous energy restriction (CER) for the entire weight loss phase (typically days to weeks). However, there is some suggestion that intermittent energy restriction (IER), which involves alternating periods of energy restriction with periods of greater energy intake (referred to as ‘refeeds’ or ‘diet breaks’) may result in superior weight loss outcomes than CER. This may be due to refeed periods causing transitory restoration of energy balance. Some studies indicate that intermittent periods of energy balance during energy restriction attenuate some of the adaptive responses that resist the continuation of weight and fat loss. While IER—like CER—is known to effectively reduce body fat in non-athletes, evidence for effectiveness of IER in athletic populations is lacking. This review provides theoretical considerations for successful body composition adjustm...
Journal of strength and conditioning research, Jan 2, 2017
Twenty young women (20.3+1.5 years, 164+6 cm, 68.7+13.8 kg) without prior structured resistance t... more Twenty young women (20.3+1.5 years, 164+6 cm, 68.7+13.8 kg) without prior structured resistance training experience were recruited for this study. Body composition (BodPod), compartmental water (Bioelectrical Impedance), 7-site skinfold, and arm and thigh CSA were assessed pre- and post- 8 week training. Performance testing consisted of vertical jump, 3 kg chest pass initial velocity, squat 1RM and overhead press 1RM. Following 2 weeks of familiarization training, subjects were matched for body composition and relative squat strength, and randomly assigned to either a high- (HL: n=10; 4 sets of 5-7 repetitions) or moderate-load (ML: n=10; 2 sets of 10-14 repetitions) group that completed 6-7 exercises per day performed to momentary muscular failure. Training was divided into two lower and one upper body training sessions per week performed on non-consecutive days for 8 weeks. There were no statistically significant main effects for group or group x time interactions for any variable...
Protein quantity and quality at a meal affect muscle protein synthesis (MPS); however, long-term ... more Protein quantity and quality at a meal affect muscle protein synthesis (MPS); however, long-term effects of protein distribution at individual meals on adult muscle mass remain unknown. We used a precise feeding protocol in adult rats to determine if optimizing postmeal MPS response by modifying the meal distribution of protein, and the amino acid leucine (Leu), would affect muscle mass. Two studies were conducted with the use of male Sprague-Dawley rats (∼300 g) trained to consume 3 meals/d, then assigned to diet treatments with identical macronutrient contents (16% of energy from protein, 54% from carbohydrates, and 30% from fat) but differing in protein quality or meal distribution. Study 1 provided 16% protein at each meal with the use of whey, egg white, soy, or wheat gluten, with Leu concentrations of 10.9%, 8.8%, 7.7%, and 6.8% (wt:wt), respectively. Study 2 used whey protein with 16% protein at each meal [balanced distribution (BD)] or meals with 8%, 8%, and 27% protein [unb...
Journal of the International Society of Sports Nutrition, 2015
Background Maintaining energy balance by consuming the required distribution of macronutrients (n... more Background Maintaining energy balance by consuming the required distribution of macronutrients (nutritional status) is important to support performance and health in collegiate athletes; however, less than 10% of NCAA athletes possess adequate sports nutrition knowledge or maintain nutritional status (Torres-McGehee et al., 2012). A recent study demonstrated that a sports nutrition education intervention (SNEI) improved nutritional knowledge and nutritional status in Division I volleyball players. This study investigated the effects of an SNEI on nutritional status, knowledge, body composition, and performance in NCAA Division I baseball players.
High-performance physical activity and postexercise recovery lead to significant changes in amino... more High-performance physical activity and postexercise recovery lead to significant changes in amino acid and protein metabolism in skeletal muscle. Central to these changes is an increase in the metabolism of the BCAA leucine. During exercise, muscle protein synthesis decreases together with a net increase in protein degradation and stimulation of BCAA oxidation. The decrease in protein synthesis is associated with inhibition of translation initiation factors 4E and 4G and ribosomal protein S6 under regulatory controls of intracellular insulin signaling and leucine concentrations. BCAA oxidation increases through activation of the branched-chain alpha-keto acid dehydrogenase (BCKDH). BCKDH activity increases with exercise, reducing plasma and intracellular leucine concentrations. After exercise, recovery of muscle protein synthesis requires dietary protein or BCAA to increase tissue levels of leucine in order to release the inhibition of the initiation factor 4 complex through activat...
two extremes. The question of protein quantity at a meal and frequency of protein consumption has... more two extremes. The question of protein quantity at a meal and frequency of protein consumption has been debated almost as often as total protein consumption. Quite often we see the question, "what is the max level of protein that one can benefit from at a meal and how often should I consume it?" Fortunately for us, this question actually has
This study examined the impact of leucine (Leu) derived from complete meals on stimulation of ske... more This study examined the impact of leucine (Leu) derived from complete meals on stimulation of skeletal muscle protein synthesis (MPS). Expt. 1 examined time course changes in translation initiation and MPS after a meal. Male rats (;300 g) were trained for 5 d to eat 3 meals/d providing 20, 50, and 30% of energy from whey protein, carbohydrates, and fats, respectively. Plasma and skeletal muscle were collected at time 0 (baseline) after 12 h of food deprivation and then at 45, 90, 135, 180, and 300 min after a 4-g meal. Plasma Leu increased at 45 min and remained elevated through 180 min. MPS peaked at 45-90 min and returned to baseline by 180 min. Plasma Leu correlated with phosphorylation of ribosomal protein p70 S6 kinase (r ¼ 0.723; P , 0.05), eukaryotic initiation factor 4E binding protein-1 (r ¼ 0.773; P , 0.05), and MPS (r ¼ 0.608; P , 0.05) over time. Expt. 2 examined 3 levels of protein intake (10, 20, and 30% of energy) from 2 sources (wheat and whey) with different Leu contents (;6.8 and ;10.9%, respectively) on stimulation of initiation and MPS. Rats were trained to eat 3 meals/d providing 14, 56, and 30% of energy from protein, carbohydrates, and fats. On d 6, MPS was evaluated at 90 min after rats consumed 1 of the 6 test meals. Whey protein stimulated initiation and MPS more than wheat and the differential response related to greater plasma Leu responses in the whey groups. These studies demonstrate that peak activation but not duration of MPS is proportional to the Leu content of a meal.
The purpose of the present study was to determine the effects of short-term supplementation with ... more The purpose of the present study was to determine the effects of short-term supplementation with the free acid form of β-hydroxy-β-methylbutyrate (HMB-FA) on indices of muscle damage, protein breakdown, recovery and hormone status following a high-volume resistance training session in trained athletes. A total of twenty resistance-trained males were recruited to participate in a high-volume resistance training session centred on full squats, bench presses and dead lifts. Subjects were randomly assigned to receive either 3 g/d of HMB-FA or a placebo. Immediately before the exercise session and 48 h post-exercise, serum creatine kinase (CK), urinary 3-methylhistadine (3-MH), testosterone, cortisol and perceived recovery status (PRS) scale measurements were taken. The results showed that CK increased to a greater extent in the placebo (329 %) than in the HMB-FA group (104 %) (P= 0·004, d= 1·6). There was also a significant change for PRS, which decreased to a greater extent in the plac...
... No Caption A... Figure. No Caption A... Image Tools. Gabriel Wilson is a doctoral student in ... more ... No Caption A... Figure. No Caption A... Image Tools. Gabriel Wilson is a doctoral student in the Division of Nutritional Sciences at the University of Illinois. Figure. ... Lawton et al. ( 16 ) demonstrated that a traditional full-RM set was detrimental to acute repetition power output. ...
ABSTRACT GROUPS OF AMINO ACIDS, AS WELL AS INDIVIDUAL AMINO ACIDS, HAVE BEEN STUDIED FOR THEIR RO... more ABSTRACT GROUPS OF AMINO ACIDS, AS WELL AS INDIVIDUAL AMINO ACIDS, HAVE BEEN STUDIED FOR THEIR ROLES IN PROTEIN BALANCE, HORMONE SECRETION, IMMUNE FUNCTION, OR CAPACITY TO BE CONVERTED TO VARIOUS ANABOLIC OR ANTICATABOLIC METABOLITES. SPECIFIC AMINO ACIDS WITH EXTENSIVE ANALYSIS INCLUDE THE ESSENTIAL AMINO ACIDS, BRANCHED CHAIN AMINO ACIDS, ARGININE, TAURINE, GLUTAMINE, β-ALANINE, AND THE LEUCINE METABOLITE, β-HYDROXY-β-METHYLBUTYRATE. THE PURPOSE OF THIS ARTICLE IS TO ANALYZE THE POSSIBLE ROLES AND PRACTICAL APPLICATIONS OF THESE AMINO ACIDS IN THE REGULATION OF BODY COMPOSITION AND PERFORMANCE IN ANAEROBIC AND AEROBIC SPORTS.
Athletes utilise numerous strategies to reduce body weight or body fat prior to competition. The ... more Athletes utilise numerous strategies to reduce body weight or body fat prior to competition. The traditional approach requires continuous energy restriction (CER) for the entire weight loss phase (typically days to weeks). However, there is some suggestion that intermittent energy restriction (IER), which involves alternating periods of energy restriction with periods of greater energy intake (referred to as ‘refeeds’ or ‘diet breaks’) may result in superior weight loss outcomes than CER. This may be due to refeed periods causing transitory restoration of energy balance. Some studies indicate that intermittent periods of energy balance during energy restriction attenuate some of the adaptive responses that resist the continuation of weight and fat loss. While IER—like CER—is known to effectively reduce body fat in non-athletes, evidence for effectiveness of IER in athletic populations is lacking. This review provides theoretical considerations for successful body composition adjustm...
Journal of strength and conditioning research, Jan 2, 2017
Twenty young women (20.3+1.5 years, 164+6 cm, 68.7+13.8 kg) without prior structured resistance t... more Twenty young women (20.3+1.5 years, 164+6 cm, 68.7+13.8 kg) without prior structured resistance training experience were recruited for this study. Body composition (BodPod), compartmental water (Bioelectrical Impedance), 7-site skinfold, and arm and thigh CSA were assessed pre- and post- 8 week training. Performance testing consisted of vertical jump, 3 kg chest pass initial velocity, squat 1RM and overhead press 1RM. Following 2 weeks of familiarization training, subjects were matched for body composition and relative squat strength, and randomly assigned to either a high- (HL: n=10; 4 sets of 5-7 repetitions) or moderate-load (ML: n=10; 2 sets of 10-14 repetitions) group that completed 6-7 exercises per day performed to momentary muscular failure. Training was divided into two lower and one upper body training sessions per week performed on non-consecutive days for 8 weeks. There were no statistically significant main effects for group or group x time interactions for any variable...
Protein quantity and quality at a meal affect muscle protein synthesis (MPS); however, long-term ... more Protein quantity and quality at a meal affect muscle protein synthesis (MPS); however, long-term effects of protein distribution at individual meals on adult muscle mass remain unknown. We used a precise feeding protocol in adult rats to determine if optimizing postmeal MPS response by modifying the meal distribution of protein, and the amino acid leucine (Leu), would affect muscle mass. Two studies were conducted with the use of male Sprague-Dawley rats (∼300 g) trained to consume 3 meals/d, then assigned to diet treatments with identical macronutrient contents (16% of energy from protein, 54% from carbohydrates, and 30% from fat) but differing in protein quality or meal distribution. Study 1 provided 16% protein at each meal with the use of whey, egg white, soy, or wheat gluten, with Leu concentrations of 10.9%, 8.8%, 7.7%, and 6.8% (wt:wt), respectively. Study 2 used whey protein with 16% protein at each meal [balanced distribution (BD)] or meals with 8%, 8%, and 27% protein [unb...
Journal of the International Society of Sports Nutrition, 2015
Background Maintaining energy balance by consuming the required distribution of macronutrients (n... more Background Maintaining energy balance by consuming the required distribution of macronutrients (nutritional status) is important to support performance and health in collegiate athletes; however, less than 10% of NCAA athletes possess adequate sports nutrition knowledge or maintain nutritional status (Torres-McGehee et al., 2012). A recent study demonstrated that a sports nutrition education intervention (SNEI) improved nutritional knowledge and nutritional status in Division I volleyball players. This study investigated the effects of an SNEI on nutritional status, knowledge, body composition, and performance in NCAA Division I baseball players.
High-performance physical activity and postexercise recovery lead to significant changes in amino... more High-performance physical activity and postexercise recovery lead to significant changes in amino acid and protein metabolism in skeletal muscle. Central to these changes is an increase in the metabolism of the BCAA leucine. During exercise, muscle protein synthesis decreases together with a net increase in protein degradation and stimulation of BCAA oxidation. The decrease in protein synthesis is associated with inhibition of translation initiation factors 4E and 4G and ribosomal protein S6 under regulatory controls of intracellular insulin signaling and leucine concentrations. BCAA oxidation increases through activation of the branched-chain alpha-keto acid dehydrogenase (BCKDH). BCKDH activity increases with exercise, reducing plasma and intracellular leucine concentrations. After exercise, recovery of muscle protein synthesis requires dietary protein or BCAA to increase tissue levels of leucine in order to release the inhibition of the initiation factor 4 complex through activat...
two extremes. The question of protein quantity at a meal and frequency of protein consumption has... more two extremes. The question of protein quantity at a meal and frequency of protein consumption has been debated almost as often as total protein consumption. Quite often we see the question, "what is the max level of protein that one can benefit from at a meal and how often should I consume it?" Fortunately for us, this question actually has
This study examined the impact of leucine (Leu) derived from complete meals on stimulation of ske... more This study examined the impact of leucine (Leu) derived from complete meals on stimulation of skeletal muscle protein synthesis (MPS). Expt. 1 examined time course changes in translation initiation and MPS after a meal. Male rats (;300 g) were trained for 5 d to eat 3 meals/d providing 20, 50, and 30% of energy from whey protein, carbohydrates, and fats, respectively. Plasma and skeletal muscle were collected at time 0 (baseline) after 12 h of food deprivation and then at 45, 90, 135, 180, and 300 min after a 4-g meal. Plasma Leu increased at 45 min and remained elevated through 180 min. MPS peaked at 45-90 min and returned to baseline by 180 min. Plasma Leu correlated with phosphorylation of ribosomal protein p70 S6 kinase (r ¼ 0.723; P , 0.05), eukaryotic initiation factor 4E binding protein-1 (r ¼ 0.773; P , 0.05), and MPS (r ¼ 0.608; P , 0.05) over time. Expt. 2 examined 3 levels of protein intake (10, 20, and 30% of energy) from 2 sources (wheat and whey) with different Leu contents (;6.8 and ;10.9%, respectively) on stimulation of initiation and MPS. Rats were trained to eat 3 meals/d providing 14, 56, and 30% of energy from protein, carbohydrates, and fats. On d 6, MPS was evaluated at 90 min after rats consumed 1 of the 6 test meals. Whey protein stimulated initiation and MPS more than wheat and the differential response related to greater plasma Leu responses in the whey groups. These studies demonstrate that peak activation but not duration of MPS is proportional to the Leu content of a meal.
The purpose of the present study was to determine the effects of short-term supplementation with ... more The purpose of the present study was to determine the effects of short-term supplementation with the free acid form of β-hydroxy-β-methylbutyrate (HMB-FA) on indices of muscle damage, protein breakdown, recovery and hormone status following a high-volume resistance training session in trained athletes. A total of twenty resistance-trained males were recruited to participate in a high-volume resistance training session centred on full squats, bench presses and dead lifts. Subjects were randomly assigned to receive either 3 g/d of HMB-FA or a placebo. Immediately before the exercise session and 48 h post-exercise, serum creatine kinase (CK), urinary 3-methylhistadine (3-MH), testosterone, cortisol and perceived recovery status (PRS) scale measurements were taken. The results showed that CK increased to a greater extent in the placebo (329 %) than in the HMB-FA group (104 %) (P= 0·004, d= 1·6). There was also a significant change for PRS, which decreased to a greater extent in the plac...
... No Caption A... Figure. No Caption A... Image Tools. Gabriel Wilson is a doctoral student in ... more ... No Caption A... Figure. No Caption A... Image Tools. Gabriel Wilson is a doctoral student in the Division of Nutritional Sciences at the University of Illinois. Figure. ... Lawton et al. ( 16 ) demonstrated that a traditional full-RM set was detrimental to acute repetition power output. ...
ABSTRACT GROUPS OF AMINO ACIDS, AS WELL AS INDIVIDUAL AMINO ACIDS, HAVE BEEN STUDIED FOR THEIR RO... more ABSTRACT GROUPS OF AMINO ACIDS, AS WELL AS INDIVIDUAL AMINO ACIDS, HAVE BEEN STUDIED FOR THEIR ROLES IN PROTEIN BALANCE, HORMONE SECRETION, IMMUNE FUNCTION, OR CAPACITY TO BE CONVERTED TO VARIOUS ANABOLIC OR ANTICATABOLIC METABOLITES. SPECIFIC AMINO ACIDS WITH EXTENSIVE ANALYSIS INCLUDE THE ESSENTIAL AMINO ACIDS, BRANCHED CHAIN AMINO ACIDS, ARGININE, TAURINE, GLUTAMINE, β-ALANINE, AND THE LEUCINE METABOLITE, β-HYDROXY-β-METHYLBUTYRATE. THE PURPOSE OF THIS ARTICLE IS TO ANALYZE THE POSSIBLE ROLES AND PRACTICAL APPLICATIONS OF THESE AMINO ACIDS IN THE REGULATION OF BODY COMPOSITION AND PERFORMANCE IN ANAEROBIC AND AEROBIC SPORTS.
Uploads
Papers by Layne Norton