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Exercise training and protein metabolism: Influences of contraction, protein intake, and sex-based differences
Abstract
Muscle contraction during exercise, whether resistive or endurance in nature, has profound affects on muscle protein turnover that can persist for up to 72 h. It is well established that feeding during the postexercise period is required to bring about a positive net protein balance (muscle protein synthesis - muscle protein breakdown). There is mounting evidence that the timing of ingestion and the protein source during recovery independently regulate the protein synthetic response and influence the extent of muscle hypertrophy. Minor differences in muscle protein turnover appear to exist in young men and women; however, with aging there may be more substantial sex-based differences in response to both feeding and resistance exercise. The recognition of anabolic signaling pathways and molecules are also enhancing our understanding of the regulation of protein turnover following exercise perturbations. In this review we summarize the current understanding of muscle protein turnover in response to exercise and feeding and highlight potential sex-based dimorphisms. Furthermore, we examine the underlying anabolic signaling pathways and molecules that regulate these processes.
... Exercise, primary resistance-based, enhances MPS. However, the consumption of protein post-exercise is necessary to maximize the rates of MPS and overall stimulation of skeletal muscle hypertrophy [223]. ...
... No studies are currently available that specifically address the protein requirements of female athletes across the menstrual cycle or with the use of hormonal contraceptives. In eumenorrheic women, evidence suggests protein catabolism is higher at rest and following aerobic endurance exercise in the luteal phase, when estrogen and progesterone are elevated, compared to the early follicular phase when estrogen and progesterone concentrations are low [81,164,223,224]. Moreover, it has been shown that protein oxidation during exercise appears to be greater during the mid-luteal phase [164,223] and that females require more lysine during the luteal phase than the follicular phase [81] with a lower ability to uptake and utilize amino acids for protein synthesis. ...
... In eumenorrheic women, evidence suggests protein catabolism is higher at rest and following aerobic endurance exercise in the luteal phase, when estrogen and progesterone are elevated, compared to the early follicular phase when estrogen and progesterone concentrations are low [81,164,223,224]. Moreover, it has been shown that protein oxidation during exercise appears to be greater during the mid-luteal phase [164,223] and that females require more lysine during the luteal phase than the follicular phase [81] with a lower ability to uptake and utilize amino acids for protein synthesis. Although the blood amino acid profiles of COC users are shown to differ from non-users [225], the impact of COC on protein metabolism needs at rest or in response to exercise is yet to be elucidated. ...
Based on a comprehensive review and critical analysis of the literature regarding the nutritional concerns of female athletes, conducted by experts in the field and selected members of the International Society of Sports Nutrition (ISSN), the following conclusions represent the official Position of the Society: 1. Female athletes have unique and unpredictable hormone profiles, which influence their physiology and nutritional needs across their lifespan. To understand how perturbations in these hormones affect the individual, we recommend that female athletes of reproductive age should track their hormonal status (natural, hormone driven) against training and recovery to determine their individual patterns and needs and peri and post-menopausal athletes should track against training and recovery metrics to determine the individuals' unique patterns. 2. The primary nutritional consideration for all athletes, and in particular, female athletes, should be achieving adequate energy intake to meet their energy requirements and to achieve an optimal energy availability (EA); with a focus on the timing of meals in relation to exercise to improve training adaptations, performance, and athlete health. 3. Significant sex differences and sex hormone influences on carbohydrate and lipid metabolism are apparent, therefore we recommend first ensuring athletes meet their carbohydrate needs across all phases of the menstrual cycle. Secondly, tailoring carbohydrate intake to hormonal status with an emphasis on greater carbohydrate intake and availability during the active pill weeks of oral contraceptive users and during the luteal phase of the menstrual cycle where there is a greater effect of sex hormone suppression on gluconogenesis output during exercise. 4. Based upon the limited research available, we recommend that pre-menopausal, eumenorrheic, and oral contraceptives using female athletes should aim to consume a source of high-quality protein as close to beginning and/or after completion of exercise as possible to reduce exercise-induced amino acid oxidative losses and initiate muscle protein remodeling and repair at a dose of 0.32-0.38 g·kg-1. For eumenorrheic women, ingestion during the luteal phase should aim for the upper end of the range due to the catabolic actions of progesterone and greater need for amino acids. 5. Close to the beginning and/or after completion of exercise, peri- and post-menopausal athletes should aim for a bolus of high EAA-containing (~10 g) intact protein sources or supplements to overcome anabolic resistance. 6. Daily protein intake should fall within the mid- to upper ranges of current sport nutrition guidelines (1.4-2.2 g·kg-1·day-1) for women at all stages of menstrual function (pre-, peri-, post-menopausal, and contraceptive users) with protein doses evenly distributed, every 3-4 h, across the day. Eumenorrheic athletes in the luteal phase and peri/post-menopausal athletes, regardless of sport, should aim for the upper end of the range. 7. Female sex hormones affect fluid dynamics and electrolyte handling. A greater predisposition to hyponatremia occurs in times of elevated progesterone, and in menopausal women, who are slower to excrete water. Additionally, females have less absolute and relative fluid available to lose via sweating than males, making the physiological consequences of fluid loss more severe, particularly in the luteal phase. 8. Evidence for sex-specific supplementation is lacking due to the paucity of female-specific research and any differential effects in females. Caffeine, iron, and creatine have the most evidence for use in females. Both iron and creatine are highly efficacious for female athletes. Creatine supplementation of 3 to 5 g per day is recommended for the mechanistic support of creatine supplementation with regard to muscle protein kinetics, growth factors, satellite cells, myogenic transcription factors, glycogen and calcium regulation, oxidative stress, and inflammation. Post-menopausal females benefit from bone health, mental health, and skeletal muscle size and function when consuming higher doses of creatine (0.3 g·kg-1·d-1). 9. To foster and promote high-quality research investigations involving female athletes, researchers are first encouraged to stop excluding females unless the primary endpoints are directly influenced by sex-specific mechanisms. In all investigative scenarios, researchers across the globe are encouraged to inquire and report upon more detailed information surrounding the athlete's hormonal status, including menstrual status (days since menses, length of period, duration of cycle, etc.) and/or hormonal contraceptive details and/or menopausal status.
... Hem endürans hem de direnç egzersizleri sonrasında protein alımının kas protein sentezini indüklediği bilinmektedir. 31,32 Yüksek şiddetli egzersiz kas protein sentezini ve yıkımını artırırken net protein dengesini oluşturur. 31 Artan protein döngüsü iskelet kasının remodelasyonunu ve plastisitesini destekleyen bir fonksiyon görür. ...
... 31,32 Yüksek şiddetli egzersiz kas protein sentezini ve yıkımını artırırken net protein dengesini oluşturur. 31 Artan protein döngüsü iskelet kasının remodelasyonunu ve plastisitesini destekleyen bir fonksiyon görür. 33 Direnç egzersizleriyle kasların diyetteki proteine 24 saat kadar duyarlı kaldığı gösterilmiş ve bu süre gelişmiş kas remodelasyonu ve adaptasyonu için "fırsat penceresi" olarak nitelendirilmiştir. ...
... 42,43 Kuvvet çalışmaları söz konusu olduğunda egzersizin indüklediği kassal büyümeyi de geliştirirler. 31 Bu nedenle diyetteki protein, kaslarda protein remodelasyonunu geliştirdiği için sporcularda toparlanma döneminde temel beslenme komponentlerinden birisi olmaktadır. Egzersiz sonrası yüksek kaliteli protein desteği (0,25 gr/kg) sağlanmalıdır. ...
30 porcular temel performans parametrelerini geliştirmeye yönelik egzersizlere antrenman programlarında yer verirler. Optimal performans düzeyi için en önemli belirleyici antrenman olmakla birlikte beslenme de çok önemli ve etkili bir komponentdir. Doğru bir beslenme planı sporcuların optimal performansın gerek-tirdiği enerji düzeyine sahip olmalarını, ideal kilolarında kalmalarını ve antrenmanın programının bütün aşamalarında kendilerini iyi hissetmelerini sağlayacaktır. İdeal bir beslenme planı oluşturmak deneyimli sporcular için bile kolay bir durum değildir. 1 Sporcu Beslenmesi ve Antrenman İlişkisi Nasıl Sağlanmalı? Ö ÖZ ZE ET T Sporda başarıyı sağlayan pek çok faktör olmakla birlikte beslenme anahtar bir rol üstlen-mektedir. Araştırma sonuçları planlı ve bilimsel bir beslenme stratejisinin sportif performansı ge-liştirdiği yönünde sonuçlar vermektedir. Sporcuya özel ve antrenman periyodizasyonuna uygun bireysel beslenme stratejisinin spor türü, performans beklentisi, hedefleri, sporcunun beslenme alış-kanlıkları ve tercihlerinin dikkate alınarak oluşturulması gerekmektedir. Sporcularda egzersiz ön-cesi optimal beslenmenin sağlanması ve egzersiz sonrası toparlanmanın desteklenmesi için yeterli düzeyde günlük enerji alımı şarttır. Total enerji ihtiyacının sağlanması kaydıyla sporcunun tercih-lerine ve toleransına göre düzenleme yapılabilir. Dengeli bir beslenme fiziksel aktivite nedeniyle artan enerji ihtiyacını karşılayabilmelidir. İyi bir beslenme, yoğun antrenman programını destek-lediği gibi kassal toparlanma ve endürans egzersizlerine olan metabolik adaptasyonu kolaylaştırır. Bu derlemede, sporcu beslenmesi ve antrenman ilişkisinin öneminden bahsedilecek ve beslenme yaklaşımları ile fizyolojik yanıtlar hakkında pratik önerilere yer verilecektir. A An na ah ht ta ar r K Ke el li im me el le er r: : Sporcular; egzersiz; beslenme durumu; spor performansı A AB BS ST TR RA AC CT T A number of factors contribute to success in sport, and diet is a key component. Research findings show that a planned scientific nutritional strategy is related to better sports performance. Individualized and periodized nutritional strategy according to training program should depend on several aspects, including the sport, the athlete's goals, the environment, and practical issues. Daily energy intake is essential in athletes, and should be timed according to training sessions in order to ensure optimal pre-workout nutrition, as well as to encourage recovery post workout. If this is not possible during the day, the intake should be tailored according to individual preference and tolerance, provided that the total daily requirements are met. Maintenance of the energy balance in individuals with increased requirements because of physical activity is important. Good nutrition assists in the ability to train intensely, as well as in muscle recovery and metabolic adaptations to endurance exercise. This review will focus on the importance of the interaction between sports nutrition and training status, and discuss practical recommendations about nutritional approaches and physiological responses. K Ke ey y W Wo or rd ds s: : Athletes; exercise; nutritional status; sports performance T Tu ur rk ki iy ye e K Kl li in ni ik kl le er ri i J J S Sp po or rt ts s M Me ed d-S Sp pe ec ci ia al l T To op pi ic cs s 2 20 01 16 6; ;2 2((3 3)):
... Muscle mass maintenance is regulated by the balance between muscle protein breakdown and synthesis rates, and muscle synthesis is highly responsive to dietary protein intake (1) . The postprandial muscle protein synthetic response to feeding is regulated on a number of levels, including dietary protein digestion, amino acid absorption, splanchnic amino acid metabolism, postprandial insulin release, amino acid uptake by muscle and cellular signalling in the muscle (1) . ...
... Muscle mass maintenance is regulated by the balance between muscle protein breakdown and synthesis rates, and muscle synthesis is highly responsive to dietary protein intake (1) . The postprandial muscle protein synthetic response to feeding is regulated on a number of levels, including dietary protein digestion, amino acid absorption, splanchnic amino acid metabolism, postprandial insulin release, amino acid uptake by muscle and cellular signalling in the muscle (1) . Previous work as reviewed by Gorissen et al. (2) has shown that the muscle protein synthetic response to feeding can be modulated by changing the amount of protein ingested and the source of dietary protein. ...
... Comparison of milk protein fractions (milk contains an 80:20 mix of casein and whey) showed that whey proteins produced a rapid, short-lived peak in plasma amino acid concentrations, whereas the plasma amino acid peak was more moderate and prolonged with casein when given as a single protein meal (3) . These differences are due to the speed at which the protein is released into the small intestine, digested and the amino acids absorbed (1,3,4) . In some studies (5,6) , the gastric emptying rate of soya protein was similar to that of milk, but stable isotope experiments (7) showed that intestinal processing of soya protein was faster overall, leading to earlier appearance of most amino acids in peripheral blood for soya (8) . ...
Soya-dairy protein blends can extend post-exercise muscle synthesis in young people more than whey protein control. Older adults differ metabolically from young people, and their ability to absorb amino acids from dietary protein is important for muscle function. The objective was to determine how protein source affects postprandial plasma amino acid response and/or metabolomic profile in older adults via a single-blind randomised crossover trial (n 16, males 50-70 years), using three nutritionally equivalent meal replacement drinks containing 30 g protein, from a 1:1 (mass ratio) soya:dairy blend, a 1:2 soya:dairy blend or whey protein. The outcome measures were plasma amino acid concentrations at 0-300 min postprandially and urine metabolomic fingerprint. Soya:dairy drinks gave similar amino acid response in plasma over time and similar urinary metabolite fingerprints. However, there were significant differences in plasma amino acid concentrations and AUC values for the soya:dairy drinks v. the whey protein drink. AUC for Leu, Trp and Lys was lower and AUC for Phe and Pro was higher for the soya:dairy drinks. Differences partly reflected the amino acid profiles of the drinks, but overall plasma amino acid response patterns were qualitatively unchanged. Plasma amino acid differences between the whey protein drink and the soya:dairy blends were reflected in urine metabolite patterns. In conclusion, postprandial plasma amino acid responses were broadly similar, irrespective of protein source (and soya:dairy ratio). There were significant differences for some plasma amino acid concentrations, reflecting different amino acid profiles of the protein source and influencing urine metabolite fingerprints.
... BCAA supplement was made of partially hydrolyzed whey protein isolates, which present the advantage of being assimilated very quickly and thereby providing essential, immediately available nutrients to muscles [72]. In our study, BCAA supplementation was ingested for lunch. ...
... In our study, BCAA supplementation was ingested for lunch. As patients were involved in physical activities, in both morning and afternoon, midday supplementation to favor muscle protein synthesis and recovery from the morning activities seemed more appropriate and relevant than intake in the evening or during breakfast [72]. Some authors have reported lower muscular gain when protein ingestion is delayed (2 h) after exercise as compared with immediate consumption [73]. ...
... Patients of both sexes were included in the study, and in each of the two groups there were approximately 1/3 women. Considering that body composition, muscle anabolism or substrate metabolism during exercise are influenced by hormones, it can be assumed that exercise rehabilitation effects may be affected by gender [72]. Nutritional adaptations are likewise impacted by sex-differences [82]. ...
Backgroung
Muscle wasting is frequent in chronic obstructive lung disease (COPD) and associated with low branched-chain amino acids (BCAA). We hypothesized that BCAA supplementation could potentiate the effect of a pulmonary rehabilitation program (PRP) by inducing muscular change.
Materials and methods
Sixty COPD patients (GOLD 2-3) were involved in an ambulatory 4-week PRP either with BCAA oral daily supplementation or placebo daily supplementation in a randomized double-blind design. Maximal exercise test including quadriceps oxygenation measurements, functional exercise test, muscle strength, lung function tests, body composition, dyspnea and quality of life were assessed before and after PRP.
Results
Fifty-four patients (64.9 ± 8.3 years) completed the protocol. In both groups, maximal exercise capacity, functional and muscle performances, quality of life and dyspnea were improved after 4-week PRP (p≤0.01). Changes in muscle oxygenation during the maximal exercise and recovery period were not modified after 4-week PRP in BCAA group. Contrarily, in the placebo group the muscle oxygenation kinetic of recovery was slowed down after PRP.
Conclusion
This study demonstrated that a 4-week PRP with BCAA supplementation is not more beneficial than PRP alone for patients. A longer duration of supplementation or a more precise targeting of patients would need to be investigated to validate an effect on muscle recovery and to demonstrate other beneficial effects.
... SKM mass is regulated by the dynamic relationship between muscle protein synthesis (MPS) and muscle protein breakdown (MPB). In the postabsorptive state, net MPB exceeds MPS whilst net MPS exceeds MPB in the postprandial state; therefore achieving net protein balance across diurnal fasted-fed cycles [5,6]. Following a protein feed, MPS increases~2e3 fold, peaking between~1.5 and 2 h post-feed whilst MPB is transiently inhibited by~50% in young healthy muscle, though this effect (i.e., increases in MPS/inhibition of MPB) is significantly blunted in older muscle [7e9]. ...
... Following a protein feed, MPS increases~2e3 fold, peaking between~1.5 and 2 h post-feed whilst MPB is transiently inhibited by~50% in young healthy muscle, though this effect (i.e., increases in MPS/inhibition of MPB) is significantly blunted in older muscle [7e9]. Indeed, both MPS and MPB are responsive to dietary protein feeding, both alone and when combined with various modalities of exercise (i.e., resistance, endurance, and concurrent exercise) [5,6], but also to periods of inactivity and disease [10e13]. ...
Muscle protein synthesis (MPS) and muscle protein breakdown (MPB) are influenced through dietary protein intake and physical (in)activity, which it follows, regulate skeletal muscle (SKM) mass across the lifespan. Following consumption of dietary protein, the bio-availability of essential amino acids (EAA), and primarily leucine (LEU), drive a transient increase in MPS with an ensuing refractory period before the next MPS stimulation is possible (due to the "muscle full" state). At the same time, MPB is periodically constrained via reflex insulin actions. Layering exercise on top of protein intake increases the sensitivity of SKM to EAA, therefore extending the muscle full set-point (∼48 h), to permit long-term remodelling (e.g., hypertrophy). In contrast, ageing and physical inactivity are associated with a premature muscle full set-point in response to dietary protein/EAA and contractile activity. Of all the EAA, LEU is the most potent stimulator of the mechanistic target of rapamycin complex 1 (mTORC1)-signalling pathway, with the phosphorylation of mTORC1 substrates increasing ∼3-fold more than with all other EAA. Furthermore, maximal MPS stimulation is also achieved following low doses of LEU-enriched protein/EAA, negating the need for larger protein doses. As a result, LEU supplementation has been of long term interest to maximise muscle anabolism and subsequent net protein accretion, especially when in tandem with resistance exercise. This review highlights current knowledge vis-à-vis the anabolic effects of LEU supplementation in isolation, and in enriched protein/EAA sources (i.e., EAA and/or protein sources with added LEU), in the context of ageing, exercise and unloading states.
... Additionally, it should be noted that it is not just the leucine content of the protein, or even the postprandial leucinemia, that solely determines postprandial myoFSR. Factors such as age, sex, health, nutritional and training status (and the interactions between them) differentially affect anabolism [25,26]. For example, ingestion of 40 g of soy protein was shown to be ineffective at increasing resting myoFSR in older men, whereas ingestion after RET led to robust increases in the myoFSR [9]. ...
... For example, ingestion of 40 g of soy protein was shown to be ineffective at increasing resting myoFSR in older men, whereas ingestion after RET led to robust increases in the myoFSR [9]. Similarly, sexually dimorphic postprandial MPS rates have been reported in older, but not younger, men and women [25][26][27][28]. Indeed, a novel aspect of the present study was the use of a mixed-sex cohort, whereas most research in this area is limited to single-sex studies (i.e., mostly men). ...
The aim of the present study was to evaluate the effect of feeding fava bean (Vicia faba L.) protein (FBP) on resting and post-exercise myofibrillar fractional synthetic rate (myoFSR). In a parallel, double-blind, randomised control trial, sixteen young, healthy recreationally active adults (age = 25 (5) years, body mass = 70 (15) kg, stature = 1.72 (0.11) m, mean (SD)) ingested 0.33 g·kg−1 FBP (n = 8) or a negative control (CON, i.e., EAA-free mixture) (n = 8), immediately after a bout of unilateral knee-extensor resistance exercise. Plasma, saliva, and m. vastus lateralis muscle samples were obtained pre-ingestion and 3 h post-ingestion. MyoFSR was calculated via deuterium labelling of myofibrillar-bound alanine, measured by gas chromatography–pyrolysis–isotope ratio mass spectrometry (GC-Pyr-IRMS). Resistance exercise increased myoFSR (p = 0.012). However, ingestion of FBP did not evoke an increase in resting (FBP 29 [−5, 63] vs. CON 12 [−25, 49]%, p = 0.409, mean % change [95% CI]) or post-exercise (FBP 78 [33, 123]% vs. CON 58 [9, 107]%, p = 0.732) myoFSR. Ingestion of 0.33 g·kg−1 of FBP does not appear to enhance resting or post-exercise myoFSR in young, healthy, recreationally active adults.
... This equilibrium has many more interweaving than it seems: for example, amino acids derived from MPB represent 80% of the daily synthetized protein whilst only 20% of the new protein derive from diet protein intake [40]. In general, nutrients intake, hormones, and activity (considered as muscle contraction) influence the balance between MPS and MPB hence the whole muscle protein balance [41]. At basal fasting conditions the muscle protein balance is negative because MPB is higher (≅ 30%) than MPS [42]. ...
... 70-85% 1RM) and related medium-low number of repetitions (6-12 reps) to optimize skeletal muscle hypertrophy, whilst higher load and relative lower repetitions are suggested to implement muscle strength [59]. Even though many metabolic mechanisms were adduced to support the superiority of medium-low number of repetitions [62], recent findings suggest that low load (thus high repetition number) could be, at least, efficient as the highest load for muscle hypertrophy [41,63,64]. These data suggest that heavy load/high-intensity training is not mandatory to elicit an increase in muscle protein synthesis which is a prerequisite for skeletal muscle hypertrophy. ...
Coronavirus disease 2019 (COVID-19) is a worldwide pandemic illness that is impacting the cardiovascular, pulmonary, musculoskeletal, and cognitive function of a large spectrum of the worldwide population. The available pharmacological countermeasures of these long-term effects of COVID-19 are minimal, while myriads of non-specific non-pharmacological treatments are emerging in the literature. In this complicated scenario, particular emphasis should be dedicated to specific exercise interventions tailored for subjects and athletes recovering from COVID-19. Specific guidelines on adapted physical activity in this critical population are unavailable so far, therefore, in this position statement of the Società Italiana di Scienze Motorie e Sportive (SISMeS) the members of the steering committee of the research group Attività Motoria Adattata, Alimentazione, Salute e Fitness have indicated the adapted physical activity approaches to counteract the long-term effects of the COVID-19, both in good health people and athletes.
... 10 In contrast to the definition of a protein requirement, a protein recommendation serves to optimise metabolic function and improve health and functional outcomes in a given population group. 11 12 Experimental studies conducted in healthy young (18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) year old) adults without PKU provide useful insight into the impact of L-AA supplementation on plasma amino acid kinetics. [13][14][15][16][17] The rapid rise in plasma amino acid concentrations observed with ingestion of L-AA has been shown to result in greater amino acid oxidation rates and lower protein retention at the whole-body level in comparison with whole protein. ...
... [18][19][20][21][22][23][24] Furthermore, age, sex and physical activity status are all known to modify the metabolic fate of ingested protein. [23][24][25][26][27] These variables are also relevant when considering research undertaken to determine protein status in individuals with PKU. In addition, there are factors unique to the dietary regimen of people with PKU that warrant consideration such as type of protein substitute (L-AA vs CGMP vs protein substitutes using prolonged release technologies), dose and timing of protein substitute ingestion, the proportion of total protein intake from dietary protein versus protein substitutes, adherence to protein substitute prescription and the period of time spent on and off a phenylalanine restricted diet. ...
Introduction
Phenylketonuria (PKU) is a disorder of protein metabolism resulting in an accumulation of phenylalanine in the body. Dietary management consists of altering the sources of ingested protein to limit phenylalanine intake. Current dietary protein guidelines for PKU are based on limited scientific evidence, thus it remains unclear whether current practice leads to optimal protein status in people with PKU. To date, no attempt has been made to systematically evaluate the protein status of people with PKU, using a combination of validated anthropometric, biochemical and functional measurement tools. Furthermore, factors known to influence protein status in the general population warrant consideration when determining protein status in individuals with PKU, alongside factors unique to PKU such as the type of protein substitute consumed. Understanding the impact of these variables on protein status is crucial to developing a personalised approach to protein recommendations for optimising health and functional outcomes in people with PKU. Therefore, the aim of this scoping review is to examine existing evidence regarding the protein status of people with PKU, and to investigate the nutritional and lifestyle variables that influence protein status.
Methods and analysis
This review will be guided by Arksey and O’Malley’s framework, along with guidance from Levac et al , Pawliuk et al and the Joanna Briggs Institute. The following databases will be searched: MEDLINE (Ovid), Embase, CENTRAL, Web of Science and Scopus, alongside grey literature. Identified literature will be assessed by two independent reviewers for inclusion. Descriptive numerical analysis will be performed and a narrative summary will accompany the tabulated results describing how study findings relate to the review questions.
Ethics and dissemination
This review protocol does not require ethical approval. Findings will be disseminated through peer-reviewed publication, presented at relevant conferences, and shared with a patient research advisory group to inform discussions on future research.
... L-leucine has been shown to independently upregulate MPS by activating the mammalian target of rapamycin complex-1 (42). Generally, it is recognized that 8-10 g (1.8-2.0 g leucine) of essential amino acids maximizes MPS with whey protein specifically leading to a rapid rise in blood amino acid concentrations and therefore MPS (43,44). Nonetheless, it is generally recognized that the total daily intake of protein and wholebody protein balance (i.e., nitrogen balance) are key determinants compared to the timing of protein intake in the context of muscle recovery (45). ...
British Army basic training (BT) is physically demanding with new recruits completing multiple bouts of physical activity each day with limited recovery. Load carriage is one of the most physically demanding BT activities and has been shown to induce acute exercise-induced muscle damage (EIMD) and impair muscle function. Protein supplementation can accelerate muscle recovery by attenuating EIMD and muscle function loss. This study investigated the impact of an additional daily bolus of protein prior to sleep throughout training on acute muscle recovery following a load carriage test in British Army recruits. 99 men and 23 women (mean ± standard deviation [SD]: age: 21.3 ± 3.5 yrs., height: 174.8 ± 8.4 cm, body mass 75.4 ± 12.2 kg) were randomised to dietary control (CON), carbohydrate placebo (PLA), moderate (20g; MOD) or high (60g; HIGH) protein supplementation. Muscle function (maximal jump height), perceived muscle soreness and urinary markers of muscle damage were assessed before (PRE), immediately post (POST), 24-hours post (24h-POST) and 40-hours post (40h-POST) a load carriage test. There was no impact of supplementation on muscle function at POST (p=0.75) or 40h-POST (p=0.989) load carriage but jump height was greater in PLA compared to HIGH at 24h-POST (p=0.037). There was no impact of protein supplementation on muscle soreness POST (p=0.605), 24h-POST (p=0.182) or 40h-POST (p=0.333). All groups had increased concentrations of urinary myoglobin and 3-methylhistidine, but there was no statistical difference between groups at any timepoint (p>0.05). We conclude that pre-sleep protein supplementation does not accelerate acute muscle recovery following load carriage in British Army recruits during basic training. The data suggests that consuming additional energy in the form of CHO or protein was beneficial at attenuating EIMD, although it is acknowledged there were no statistical differences between groups. Although EIMD did occur as indicated by elevated urinary muscle damage markers, it is likely that the load carriage test was not arduous enough to reduce muscle function, limiting the impact of protein supplementation. Practically, protein supplementation above protein intakes of 1.2g⸱kg-1⸱day-1 following load carriage over similar distances (4km) and carrying similar loads (15-20kg) does not appear to be warranted.
... Protein synthesis and turnover were upregulated both in response to acute AE and the combination of acute AE and PI but not in response to PI alone, which indicated that acute AE had a strong effect on protein synthesis and turnover and this effect may be enhanced when PI was added. This is reasonable in that muscle contraction during exercise, whether RE or EE, has a profound effect on muscle protein turnover [72]. These findings were also consistent with the reports from previous RCTs [73,74], which indicated that PI alone could not modulate myofibrillar protein synthesis (MyoPS) rates that were caused by disuse, while pre-sleep protein ingestion could stimulate myofibrillar and mitochondrial protein synthesis during an overnight recovery from AE. ...
This study aimed to provide a more comprehensive molecular insight into the effects of aerobic exercise (AE), protein intake (PI), and AE combined with PI on human skeletal muscle by comparing their transcriptomic profiles. Fourteen published datasets obtained from the Gene Expression Omnibus (GEO) database were used. The hub genes were identified in response to acute AE (ACTB, IL6), training AE (UBB, COL1A1), PI (EZH2), acute AE combined with PI (DDIT3), and training AE combined with PI (MYC). Both FOS and MYC were upregulated in response to acute AE, and they were, respectively, downregulated by higher PI and a combination of AE and PI. COL1A1 was upregulated by training AE but was downregulated by higher PI. Results from the gene set enrichment analysis (p < 0.05 and FDR < 25%) showed that AE and PI delivered their impacts on human skeletal muscle in analogous pathways, including aerobic respiration, mitochondrial complexes, extracellular matrix (ECM) remodeling, metabolic process, and immune/inflammatory responses, whereas, PI may attenuate the response of immune/inflammation and ECM remodeling which would be promoted by AE, irrespective of its types. Compared to PI alone, acute AE combined with PI would further promote protein turnover and synthesis, but suppress skeletal muscle contraction and movement.
... The reasons for such interrogations are twofold. First, data in the field indicate that muscle protein synthesis (rather than muscle proteolysis) is more responsive to mechanical loading during well-fed states (579,580), and Brook et al. (581) have similarly suggested that ". . .the measurement of [muscle protein synthesis] remains a cornerstone for understanding the control of hypertrophy-mainly because it is the underlying driving force behind skeletal muscle hypertrophy." ...
Mechanisms underlying mechanical overload-induced skeletal muscle hypertrophy have been extensively researched since the landmark report by Morpurgo (1897) of "work-induced hypertrophy" in dogs that were treadmill-trained. Much of the pre-clinical rodent and human resistance training research to date supports that involved mechanisms include enhanced mammalian/mechanistic target of rapamycin complex 1 (mTORC1) signaling, an expansion in translational capacity through ribosome biogenesis, increased satellite cell abundance and myonuclear accretion, and post-exercise elevations in muscle protein synthesis rates. However, several lines of past and emerging evidence suggest additional mechanisms that feed into or are independent of these processes are also involved. This review will first provide a historical account as to how mechanistic research into skeletal muscle hypertrophy has progressed. A comprehensive list of mechanisms associated with skeletal muscle hypertrophy is then outlined and areas of disagreement involving these mechanisms are presented. Finally, future research directions involving many of the discussed mechanisms will be proposed.
... The smaller changes in lean body mass in women might be due to older women"s decreased hypertrophy capacity in response to RE and their impaired ability to increase muscle protein synthesis after protein consumption. 40 However, more research is needed to substantiate this. ...
... Since there is little evidence to suggest sex differences in the anabolic response from RET with similar training statues [20], we opted to include male and female subjects. While hormonal variation does appear to uniquely impact women physiologically, there is no clear evidence that the menstrual cycle or oral contraceptive use significantly influences physical performance [21,22]. ...
Background
Resistance exercise training (RET) is a common and well-established method to induce hypertrophy and improvement in strength. Interestingly, fish oil supplementation (FOS) may augment RET-induced adaptations. However, few studies have been conducted on young, healthy adults.
Methods
A randomized, placebo-controlled design was used to determine the effect of FOS, a concentrated source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), compared to placebo (PL) on RET-induced adaptations following a 10-week RET program (3 days·week⁻¹). Body composition was measured by dual-energy x-ray absorptiometry (LBM, fat mass [FM], percent body fat [%BF]) and strength was measured by 1-repetition maximum barbell back squat (1RMSQT) and bench press (1RMBP) at PRE (week 0) and POST (10 weeks). Supplement compliance was assessed via self-report and bottle collection every two weeks and via fatty acid dried blood spot collection at PRE and POST. An a priori α-level of 0.05 was used to determine statistical significance and Cohen’s d was used to quantify effect sizes (ES).
Results
Twenty-one of 28 male and female participants (FOS, n = 10 [4 withdrawals]; PL, n = 11 [3 withdrawals]) completed the 10-week progressive RET program and PRE/POST measurements. After 10-weeks, blood EPA+DHA substantially increased in the FOS group (+109.7%, p< .001) and did not change in the PL group (+1.3%, p = .938). Similar between-group changes in LBM (FOS: +3.4%, PL: +2.4%, p = .457), FM (FOS: −5.2%, PL: 0.0%, p = .092), and %BF (FOS: −5.9%, PL: −2.5%, p = .136) were observed, although, the between-group ES was considered large for FM (d = 0.84). Absolute and relative (kg·kg [body mass]⁻¹) 1RMBP was significantly higher in the FOS group compared to PL (FOS: +17.7% vs. PL: +9.7%, p = .047; FOS: +17.6% vs. PL: +7.3%, p = .011; respectively), whereas absolute 1RMSQT was similar between conditions (FOS: +28.8% vs. PL: +20.5%, p = .191). Relative 1RMSQT was higher in the FOS group (FOS: +29.3% vs. PL: +17.9%, p = .045).
Conclusions
When combined with RET, FOS improves absolute and relative 1RM upper-body and relative 1RM lower-body strength to a greater extent than that observed in the PL group of young, recreationally trained adults.
... Endurance exercise, such as jogging or walking, enhances moderately the loads on the skeleton above gravity, so it does not increase muscle cross-sectional area (CSA), which is directly related to muscle strength and power. [17,18] However, resistance exercise, such as weight training, is known to prevent the pathology of osteoporosis. [19,20] Therefore, a combination of walking and resistance exercise is expected to have a greater impact on muscle mass and bone structure or bone density than just walking. ...
Background:
This study aimed to analyze the effects of walking and resistance exercises on bone structure, bone mineral density (BMD), and skeletal muscle mass. We used data from the fourth Korean National Health and Nutrition Examination Survey (KNHANES).
Methods:
A total of 3,477 participants aged ≥19 years underwent hip structural analysis (HSA), BMD, and skeletal muscle index (SMI). All radiologic evaluations were performed using dual energy X-ray absorptiometry (DXA). The Korean short version of the International Physical Activity Questionnaire was used to measure physical activity status. The physical activity recommendations of the American College of Rheumatology Work Group Panel were used to evaluate the extent of activity.
Results:
The BMD and SMI in the group in which walking activity was performed 5 days or more per week for at least 30 min per day were significantly higher than those in the group in which walking activity was not performed. HSA and SMI in the group in which resistance exercise was performed 2 days or more per week for at least 30 min per day were found to be significantly higher than those in the group in which strengthening exercises were not performed.
Conclusions:
If resistance exercise and walking are combined, bone loss and muscle loss are prevented maintaining cortical thickness in the elderly. Walking for more than 5 days a week and resistance exercise for more than 2 days a week will help to maintain the skeletal muscle as well as the cortex around the femur neck, thus helping to prevent fragility fractures in older individuals.
... While initial research had suggested a greater muscle protein synthetic response to resistance training when nutritional support was provided before compared with after resistance exercise (Tipton et al., 2001), this has not been replicated elsewhere (Fujita et al., 2009;Tipton et al., 2007). Consequently, current guidelines advocate protein ingestion at a time that coincides with maximal stimulation of muscle protein synthesis, which is after exercise (Burd, Tang, Moore, & Phillips, 2009). ...
... Acute exercise combined with protein or amino acid intake can enhance muscle protein anabolic response by activating the mTORC1 pathway, which is beneficial to promoting post-exercise recovery [55]. In this study, although the supplementation with L-PS23 or HK-PS23 probiotics alone may promote the absorption and utilization of protein in the diet, thereby promoting muscle recovery ( Figure 3A,B), further research is still needed. ...
Excessive, high-intensity or inappropriate exercise may cause muscle damage. How to speed up recovery and reduce exercise discomfort are currently very important issues for athletes and sports people. Past research has shown that probiotics can improve inflammation and oxidative stress, as well as improve exercise performance and antifatigue. However, further research is needed to confirm the recovery benefits for muscle damage. In this double-blind design study, all subjects were randomly assigned to placebo, a live Lactobacillus paracasei group (L-PS23, 2 × 1010 colony forming unit (CFU)/day), or a heat-killed L. paracasei group (HK-PS23, 2 × 1010 cells/day), and supplemented for six consecutive weeks. Afterwards, subjects completed 100 maximal vertical jumps to bring about exercise-induced muscle damage (EIMD). Countermovement jump (CMJ), isometric mid-thigh pull (IMTP), and Wingate anaerobic test (WAnT), as well as blood tests for markers of muscle damage and inflammation were made pre-exercise and 3, 24, 48 h post exercise. The results show that both L-PS23 and HK-PS23 supplementation significantly slowed the loss of muscle strength after muscle injury, and they significantly reduced the production of markers of muscle damage and inflammation (p < 0.05). In addition, L-PS23 and HK-PS23 had the benefits of accelerating the recovery and improvement of muscle strength, the blood markers of muscle injury and inflammation, and slowing the decline in testosterone concentrations (p < 0.05). Especially in the HK-PS23 supplemented group, there was a better trend. In conclusion, we found that L-PS23 or HK-PS23 supplementation for six weeks prevented strength loss after muscle damage and improved blood muscle damage and inflammatory markers, with protective, accelerated recovery and anti-fatigue benefits.
... Participants were considered resistance trained if they were engaged in resistance training >3 times per week for >3 months prior to taking part in the study. This population was selected as training status impacts the anabolic response to exercise (16) . Therefore, selecting resistance trained individuals ensured optimal exercise execution, (more) ecological validity (to exercise training) and an assumed greater homogeneity of responses to exercise. ...
Ingestion of mycoprotein stimulates skeletal muscle protein synthesis (MPS) rates to a greater extent than concentrated milk protein when matched for leucine content, potentially attributable to the whole-food nature of mycoprotein. We hypothesised that bolus ingestion of mycoprotein as part of its whole food matrix would stimulate MPS rates to a greater extent compared with a leucine matched bolus of protein concentrated from mycoprotein. Twenty-four healthy young (age; 21±2 y, BMI; 24±3 kg.m ² ) males received primed, continuous infusions of L-[ ring - ² H 5 ]phenylalanine and completed a bout of unilateral resistance leg exercise before ingesting either 70 g mycoprotein (MYC; 31.4 g protein, 2.5 g leucine; n =12) or 38.2 g of a protein concentrate obtained from mycoprotein (PCM; 28.0 g protein, 2.5 g leucine; n =12). Blood and muscle samples ( vastus lateralis ) were taken pre- and (4 h) post- exercise/protein ingestion to assess postabsorptive and postprandial myofibrillar protein fractional synthetic rates (FSRs) in resting and exercised muscle. Protein ingestion increased plasma essential amino acid and leucine concentrations ( P <0.0001), but more rapidly (both 60 vs 90 min; P <0.0001) and to greater magnitudes (1367 vs 1346 μmol·L ⁻¹ and 298 vs 283 μmol·L ⁻¹ , respectively; P <0.0001) in PCM compared with MYC. Protein ingestion increased myofibrillar FSRs ( P <0.0001) in both rested (MYC, Δ0.031±0.007%·h ⁻¹ and PCM, Δ0.020±0.008%·h ⁻¹ ) and exercised (MYC, Δ0.057±0.011%·h ⁻¹ and PCM, Δ0.058±0.012%·h ⁻¹ ) muscle, with no differences between conditions ( P >0.05). Mycoprotein ingestion results in equivalent postprandial stimulation of resting and post-exercise myofibrillar protein synthesis rates irrespective of whether it is consumed within or without its whole-food matrix.
... Maintaining the mass of skeletal muscle is of great importance in maintaining functional capacity and metabolic health. Muscle mass persistence is regulated by fluctuations in muscle protein synthesis and breakdown (7). Proteins obtained as a result of feed consumption stimulate muscle protein synthesis by providing substrates (i.e. ...
This study aimed to determine the metabolomic characteristics associated with the fattening performance of the Awassi lamb breed under intensive fattening for 90 days. Twenty-four lambs were used in the research. The lambs were divided into two groups according to their fattening performance (good fattening performance, n = 12, and poor fattening performance, n = 12), and their metabolomic properties were evaluated. The differences between the two research groups in the amino acids of alloisoleucine, aspartic acid, histidine, hydroxylysine, isoleucine, lysine, methionine, phenylalanine, tryptophan, valine, and 1-methylhistidine were found to be statistically significant (P ≤ 0.001). Moderately significant negative correlations were found between daily concentrate feed intake and 3-methylhistidine (r = −0.469; P = 0.021), hydroxylysine (r = −0.408; P = 0.048), and serotonin (r= −0.467; P = 0.021); as well as between the average daily weight gain (ADWG) and alloisoleucine (r = −0.528; P = 0.008), 3-methylhistidine (r = −0.440; P = 0.032), and hydroxylysine (r = −0.577; P = 0.003). A moderate positive correlation was found between hydroxyisovalerylcarnitine and ADWG (r = 0.476; P = 0.019), and a negative correlation was found between hydroxyisovalerylcarnitine and the feed conversion ratio (r = −0.430; P = 0.036). Pathway analysis revealed that the most important biological pathway was the phenylalanine, tyrosine, and tryptophan biosynthesis pathway. The results of the research reveal the potential for plasma free amino acid and carnitine profiles to be used as candidate biomarkers in the evaluation of fattening performance in lambs.
... Protein synthesis may be stimulated by different factors, including resistance training and dietary proteins (amino acids). It has been shown that resistance training and protein consumption independently stimulate muscle protein synthesis with (leg press) synergistic effects on skeletal muscle anabolism [29][30][31]. Thus, the association of these strategies may be considered a more effective alternative to promote an increase in lean body mass and attenuate the progression of sarcopenia in older individuals. ...
Background:
There are some controversial findings regarding the benefits of combining protein supplementation with resistance training in order to optimize adaptations to training in older adults.
Objective:
The aim of this review was to summarize the evidence from meta-analyses assessing the effects of protein supplementation combined with resistance training on body composition and muscle strength in the older population.
Methods:
We included systematic reviews with meta-analyses of randomized clinical trials that examined the effects of protein and/or amino acid supplementation associated with resistance training compared with resistance training alone on lean body mass, muscle mass, and muscle strength in older people. The search was performed using the MEDLINE (PubMed), Embase, Cochrane Database of Systematic Reviews, Google Scholar, and OpenGrey databases. Methodological quality was assessed using the Assessing the Methodological Quality of Systematic Reviews 2 checklist, and the quality of evidence was determined using the Grading of Recommendations Assessment, Development and Evaluation system. The pooled effect estimates were computed from the standardized mean difference and the 95% confidence interval achieved by each meta-analysis, using random effects models.
Results:
Five reviews were included, all of moderate methodological quality. In the analyses, protein supplementation combined with resistance training was associated with greater increases in lean body mass and muscle mass when compared with resistance training alone. However, no differences were observed between the interventions on muscle strength increases. The quality of evidence ranged from moderate to very low.
Conclusion:
Protein supplementation associated with resistance training induces greater increases in lean body mass compared with resistance training alone. In addition, it is suggested that the use of protein supplementation enhances gains in muscle mass but does not promote greater increases in muscle strength.
... Therefore, under the two synergistic effects, it has the benefit of increasing net muscle protein synthesis (Tipton et al., 1999;Franceschi et al., 2018). In addition, acute exercise combined with the ingestion of protein or amino acids can enhance the muscle protein anabolic response by activating the mTORC1 pathway, which is beneficial for promoting recovery following exercise and may improve muscle mass and quality over the long term (Burd et al., 2009). However, resistance training and protein supplementation are not as effective for the elderly as for the young, which is called the chronic slow response of the elderly (Kumar et al., 2009). ...
Background/Purpose: In recent years, the aging population has gradually increased, and the aging process is accompanied by health-associated problems, such as loss of muscle mass and weakness. Therefore, it is important to explore alternative strategies for improving the health status and physical fitness of the aged population. In this study, we investigated the effect of soy protein supplementation combined with resistance training on changes in the muscle mass, muscle strength, and functional activity performance of aging mice.
Methods: Female Institute of Cancer Research (ICR) mice were divided into four groups ( n = 8 per group): sedentary control (SC), isolated soy protein (ISP) supplementation, resistance training (RT), and a combination of ISP and RT (ISP + RT). The mice in designated groups received oral ISP supplementation (0.123 g/kg/day), RT (5 days/week for a period of 4 weeks), or a combination of both ISP plus RT for 4 weeks. Afterward, we assessed muscle strength, endurance, and anaerobic endurance performance and analyzed blood biochemical and pathological tissue sections to investigate whether there were adverse effects or not in mice.
Results: ISP supplementation effectively improved the muscle mass, muscle endurance, and endurance performance of aging female mice. The RT group not only showed similar results with ISP but also increased muscle strength and glycogen content. Nevertheless, the combination of ISP supplementation and RT had greater beneficial effects on muscle strength, physical performance, and glycogen levels ( p < 0.05). In addition, the combination of ISP supplementation and RT had significantly increased type II muscle percentage and cross-sectional area ( p < 0.05).
Conclusion: Although ISP or RT alone improved muscle mass and performance, the combination of ISP with RT showed greater beneficial effects in aging mice. Our findings suggest that regular exercise along with protein supplementation could be an effective strategy to improve overall health and physical fitness among the elderly.
... One of the tissues that has been intensively studied in relation to the effect of postprandial increase in blood amino acids, is skeletal muscle. Muscle tissue is in a constant state of turnover and muscle mass is maintained by a tightly controlled balance between muscle protein synthesis and breakdown (Burd et al. 2009). ...
It is well-known that the postprandial muscle protein synthetic response to protein ingestion is regulated on various levels, including dietary protein digestion and amino acid (AA) absorption, splanchnic AA retention, the availability of dietary protein-derived AA in the circulation, delivery of AA to the muscle, uptake of AA by the muscle, and intramuscular signaling. AA availability after consumption of dairy products is primarily determined by the rate of gastric emptying of milk proteins, which is mainly linked to coagulation of milk proteins in the stomach. Caseins form gastric coagula, which make their gastric emptying and subsequent postprandial aminoacidemia notably slower than that of whey proteins. Only recently, the role of processing, food structure, preservation and matrix on coagulation herein has been getting attention. In this review we describe various processes, that affect gastric coagulation of caseins and therewith control gastric emptying, such as the conversion to caseinate, heat treatment in the presence of whey proteins, conversion to stirred yoghurt and enzymatic hydrolysis. Modulating product characteristics by processing can be very useful to steer the gastric behavior of protein, and the subsequent digestion and AA absorption and muscle anabolic response to maintain or increase muscle mass.
... Thus, the preservation or even increase of skeletal muscle mass and strength are of fundamental importance to sustain and improve many physiological functions including a healthy aging process with the longest possible maintenance of activities of daily living (Wang et al., 2020). Resistance exercise in combination with protein ingestion is known to be a potent stimulator of skeletal muscle protein synthesis and the timely coordinated combination of both has been demonstrated to augment net muscle protein synthesis (Burd et al., 2009;Wirth et al., 2020). ...
Previous evidence suggests that resistance training in combination with specific collagen peptides (CP) improves adaptive responses of the muscular apparatus. Although beneficial effects have been repeatedly demonstrated, the underlying mechanisms are not well understood. Therefore, the primary objective of the present randomized trial was to elucidate differences in gene expression pathways related to skeletal muscle signal transduction following acute high-load resistance exercise with and without CP intake. Recreationally active male participants were equally randomized to high-load leg extension exercise in combination with 15 g CP or placebo (PLA) supplementation. Muscle biopsies from the vastus lateralis muscle were obtained at baseline as well as 1, 4 and 24 h post exercise to investigate gene expression using next generation sequencing analysis. Several important anabolic pathways including PI3K-Akt and MAPK pathways were significantly upregulated at 1 and 4 h post-exercise. Significant between-group differences for both pathways were identified at the 4 h time point demonstrating a more pronounced effect after CP intake. Gene expression related to the mTOR pathway demonstrated a higher visual increase in the CP group compared to PLA by trend, but failed to achieve statistically significant group differences. The current findings revealed a significantly higher upregulation of key anabolic pathways (PI3K-Akt, MAPK) in human skeletal muscle 4 h following an acute resistance training combined with intake of 15 g of specific collagen peptides compared to placebo. Further investigations should examine potential relationships between upregulated gene expression and changes in myofibrillar protein synthesis as well as potential long-term effects on anabolic pathways on the protein level.
... Feeding induces overall protein accrual in skeletal muscle by increasing the rate of protein synthesis and concomitantly decreasing, although to lower extent, that of protein breakdown in muscle (Burd et al., 2009). Among nutrients, amino acids are the most powerful stimuli for increasing protein synthesis in muscle (Wolfe, 2002). ...
Studies investigating the proteome of skeletal muscle present clear evidence that protein metabolism is altered in muscle of humans with obesity. Moreover, muscle quality (i.e., strength per unit of muscle mass) appears lower in humans with obesity. However, relevant evidence to date describing the protein turnover, a process that determines content and quality of protein, in muscle of humans with obesity is quite inconsistent. This is due, at least in part, to heterogeneity in protein turnover in skeletal muscle of humans with obesity. Although not always evident at the mixed-muscle protein level, the rate of synthesis is generally lower in myofibrillar and mitochondrial proteins in muscle of humans with obesity. Moreover, alterations in the synthesis of protein in muscle of humans with obesity are manifested more readily under conditions that stimulate protein synthesis in muscle, including the fed state, increased plasma amino acid availability to muscle, and exercise. Current evidence supports various biological mechanisms explaining impairments in protein synthesis in muscle of humans with obesity, but this evidence is rather limited and needs to be reproduced under more defined experimental conditions. Expanding our current knowledge with direct measurements of protein breakdown in muscle, and more importantly of protein turnover on a protein by protein basis, will enhance our understanding of how obesity modifies the proteome (content and quality) in muscle of humans with obesity.
... From a practical perspective (at least for players who perform on pitch soccer training in the morning), it would therefore seem pertinent to perform strength training in the afternoon following both recovery from morning soccer training and high CHO intake at lunch (i.e., >2 g.kg −1 ). Additionally, CHO and protein should be consumed immediately post-resistance training to augment muscle glycogen resynthesis and ensure sufficient energy availability to promote MPS (Burd et al., 2009;van Loon et al., 2000). Given that concurrent training days involve twice per day training and hence a greater absolute energy demand, it is suggested that daily CHO intake should at least equate to 6 g. kg −1 body mass. ...
Despite more than four decades of research examining the physical demands of match-play, quantification of the customary training loads of adult male professional soccer players is comparatively recent. The training loads experienced by players during weekly micro-cycles are influenced by phase of season, player position, frequency of games, player starting status, player-specific training goals and club coaching philosophy. From a macronutrient perspective, the periodization of physical loading within (i.e., match versus training days) and between contrasting micro-cycles (e.g., 1, 2 or 3 games per week schedules) has implications for daily carbohydrate (CHO) requirements. Indeed, aside from the well-recognised role of muscle glycogen as the predominant energy source during match-play, it is now recognised that the glycogen granule may exert regulatory roles in activating or attenuating the molecular machinery that modulate skeletal muscle adaptations to training. With this in mind, the concept of CHO periodization is gaining in popularity, whereby CHO intake is adjusted day-by-day and meal-by-meal according to the fuelling demands and specific goals of the upcoming session. On this basis, the present paper provides a contemporary overview and theoretical framework for which to periodize CHO availability for the professional soccer player according to the "fuel for the work" paradigm.
... At the molecular level, the mechanistic target of rapamycin complex 1 (mTORC1) signaling cascade appears to be a key mediator of acute exercise [47,48] and amino acid [49] mediated increases in MPS. Repeated bouts of resistance exercise coupled with the ingestion of dietary protein are thought to result in the repeated stimulation of MPS with each exercise bout, that over time culminates in the accretion of skeletal muscle protein and leads to increases in muscle size [50][51][52]. In support of this notion, meta-analyses [53,54] have demonstrated that protein supplementation during prolonged isolated resistance exercise training significantly enhances resistance exercise training-mediated increases in muscle size and strength in healthy adults. ...
Background
Engaging in both resistance and endurance exercise within the same training program, termed ‘concurrent exercise training,’ is common practice in many athletic disciplines that require a combination of strength and endurance and is recommended by a number of organizations to improve muscular and cardiovascular health and reduce the risk of chronic metabolic disease. Dietary protein ingestion supports skeletal muscle remodeling after exercise by stimulating the synthesis of muscle proteins and can optimize resistance exercise-training mediated increases in skeletal muscle size and strength; however, the effects of protein supplementation on acute and longer-term adaptive responses to concurrent resistance and endurance exercise are unclear.
Objectives
The purpose of this systematic review is to evaluate the effects of dietary protein supplementation on acute changes in muscle protein synthesis and longer-term changes in muscle mass, strength, and aerobic capacity in responses to concurrent resistance and endurance exercise in healthy adults.
Methods
A systematic search was conducted in five databases: Scopus, Embase, Medline, PubMed, and Web of Science. Acute and longer-term controlled trials involving concurrent exercise and protein supplementation in healthy adults (ages 18–65 years) were included in this systematic review. Main outcomes of interest were changes in skeletal muscle protein synthesis rates, muscle mass, muscle strength, and whole-body aerobic capacity (i.e., maximal/peak aerobic capacity [VO2max/peak]). The quality of studies was assessed using the National Institute of Health Quality Assessment for Controlled Intervention Studies.
Results
Four acute studies including 84 trained young males and ten longer-term studies including 167 trained and 391 untrained participants fulfilled the eligibility criteria. All included acute studies demonstrated that protein ingestion enhanced myofibrillar protein synthesis rates, but not mitochondrial protein synthesis rates during post-exercise recovery after an acute bout of concurrent exercise. Of the included longer-term training studies, five out of nine reported that protein supplementation enhanced concurrent training-mediated increases in muscle mass, while five out of nine studies reported that protein supplementation enhanced concurrent training-mediated increases in muscle strength and/or power. In terms of aerobic adaptations, all six included studies reported no effect of protein supplementation on concurrent training-mediated increases in VO2max/peak.
Conclusion
Protein ingestion after an acute bout of concurrent exercise further increases myofibrillar, but not mitochondrial, protein synthesis rates during post-exercise recovery. There is some evidence that protein supplementation during longer-term training further enhances concurrent training-mediated increases in skeletal muscle mass and strength/power, but not whole-body aerobic capacity (i.e., VO2max/peak).
... Muscle mass can be increased effectively by accelerating muscle protein synthesis (MPS) using resistance exercise training (RET) [6]. Furthermore, daily total protein intake is an important factor associated with RET-induced muscle accretion [7]. ...
Objective
To observe the relationship of the protein intake at each meal and daily total with change in lean tissue mass with progressive resistance exercise training (RET) in healthy middle-aged women.
Research Methods & Procedures
Twenty-two healthy Japanese women were recruited from Shiga Prefecture, Japan, and a supervised whole-body RET program was conducted twice a week for 16 weeks. The dietary intake was assessed using 3-day dietary records. Dual-energy X-ray absorptiometry was used to measure the whole-body lean soft tissue mass (WLTM). Multiple regression analysis was performed to examine the relationship between the protein intake and RET-induced changes in the WLTM after adjusting for age, sleep quality, physical activity, and energy intake.
Results
The 16-week RET caused a significant gain in the WLTM (1.46 ± 0.45 %, P = 0.004). Multiple regression analysis showed that the baseline protein intake at breakfast was negatively associated with the % change in the WLTM. (β = -1.598; P = 0.022). In addition, the % change (β = 0.624; P = 0.018) in the protein intake at breakfast was positively associated with the % change in the WLTM.
Conclusion
Increasing protein intake at breakfast may contribute to RET-induced muscle hypertrophy in middle-aged women, especially among those who habitually consume low protein levels at breakfast. However, future studies with larger sample sizes are still needed to confirm the importance of protein intake at breakfast.
... The mechanisms behind weight-loss-induced reductions in LBM are not fully understood, however; the impact of energy restriction on protein turnover and net muscle protein balance may be a contributing factor [6]. Skeletal muscle mass is determined by a balance between muscle protein synthesis (MPS) and muscle protein breakdown (MPB), which remains equal during energy balance [7]. Conversely, during short-term, continuous energy restriction, both post-prandial and post-absorptive MPS are reduced [8], which may lead to an overall negative protein balance, higher protein catabolism to supply amino acids and reductions in muscle mass [6]. ...
Purpose
The objective of this study was to compare the effects of 12 weeks of resistance training combined with either 5:2 intermittent fasting or continuous energy restriction on body composition, muscle size and quality, and upper and lower body strength.
Methods
Untrained individuals undertook 12 weeks of resistance training plus either continuous energy restriction [20% daily energy restriction (CERT)] or 5:2 intermittent fasting [~ 70% energy restriction 2 days/week, euenergetic consumption 5 days/week (IFT)], with both groups prescribed a mean of ≥ 1.4 g of protein per kilogram of body weight per day. Participants completed 2 supervised resistance and 1 unsupervised aerobic/resistance training combination session per week. Changes in lean body mass (LBM), thigh muscle size and quality, strength and dietary intake were assessed.
Results
Thirty-four participants completed the study (CERT = 17, IFT = 17). LBM was significantly increased (+ 3.7%, p < 0.001) and body weight (− 4.6%, p < 0.001) and fat (− 24.1%, p < 0.001) were significantly reduced with no significant difference between groups, though results differed by sex. Both groups showed improvements in thigh muscle size and quality, and reduced intramuscular and subcutaneous fat assessed by ultrasonography and peripheral quantitative computed tomography (pQCT), respectively. The CERT group demonstrated a significant increase in muscle surface area assessed by pQCT compared to the IFT group. Similar gains in upper and lower body strength and muscular endurance were observed between groups.
Conclusion
When combined with resistance training and moderate protein intake, continuous energy restriction and 5:2 intermittent fasting resulted in similar improvements in body composition, muscle quality, and strength. ACTRN: ACTRN12620000920998, September 2020, retrospectively registered.
... Growth performance can be partly reflected in the dynamic balance of muscle protein synthesis and degradation (Zeitz et al., 2019). Skeletal muscle protein turnover is the ratio between protein synthesis and protein breakdown rates (Burd et al., 2009). When positive, protein synthesis is higher than breakdown, and results in muscle mass gain. ...
This study was conducted to investigate the effects of substitution of dietary fishmeal (FM) by compound plant protein supplemented with essential amino acids on growth performance, plasma physiology, and muscle growth-related genes of gibel carp (Carassius auratus gibelio). Four diets with equal digestible protein were prepared, where 30FM (control feed) contained 30% FM and land animal protein as a protein source, 10FM contained 10% FM, PMAa contained full plant meal (PM) supplemented with crystalline amino acid, and PM contained full PM feed. There was no significant difference in the specific growth rate (SGR) with 30FM, 10FM, and PMAa diets (p > 0.05); however, the SGR of PM group was the lowest with significant difference (p < 0.05). Feed efficiency of the PM group was the lowest with significant difference (p < 0.05). The whole-body crude protein content of fish in PMAa group was significantly higher than that in each group with additional FM (p < 0.05). There were no significant differences in plasma total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) or low-density lipoprotein cholesterol (LDL-C), and free amino acid profile of 30FM, 10FM, and PMAa groups (p > 0.05); however, they were significantly higher than that in PM group (p < 0.05). The expression of key genes in the TOR signaling pathway (tor, s6k1, 4e-bp2, and eif4e), autophagy (ulk1 and atg13), and ubiquitin–proteasome (trim63 and znrf2) system of the PMAa group was similar to that of the FM group (p > 0.05), indicating that the muscle growth-related biomarker genes were positively regulated by the appropriate dietary amino acid composition at the transcriptional level. These results suggest that FM in gibel carp diet can be totally replaced by PM without negative impact on growth performance and muscle growth-related biomarkers at the transcriptional level, which provided the requirement of digestible protein and balanced amino acid profile is satisfied.
... The smaller changes in lean body mass in women might be due to older women's decreased hypertrophy capacity in response to RE and their impaired ability to increase muscle protein synthesis after protein consumption. 170 However, more research is needed to substantiate this. Conversely, two other meta-analyses found no difference in effects of RE and PS on changes in FFM between sexes. ...
... Protein ingestion enhances acute rates of MPS that, over time, promotes the accrual of muscle proteins forming the basis for muscle hypertrophy [56,57]. Dietary protein stimulates MPS by initiating the transfer and incorporation of amino acids from these dietary protein sources into skeletal muscle proteins. ...
Concurrent training incorporates dual exercise modalities, typically resistance and aerobic-based exercise, either in a single session or as part of a periodized training program, that can promote muscle strength, mass, power/force and aerobic capacity adaptations for the purposes of sports performance or general health/wellbeing. Despite multiple health and exercise performance-related benefits, diminished muscle hypertrophy, strength and power have been reported with concurrent training compared to resistance training in isolation. Dietary protein is well-established to facilitate skeletal muscle growth, repair and regeneration during recovery from exercise. The degree to which increased protein intake can amplify adaptation responses with resistance exercise, and to a lesser extent aerobic exercise, has been highly studied. In contrast, much less focus has been directed toward the capacity for protein to enhance anabolic and metabolic responses with divergent contractile stimuli inherent to concurrent training and potentially negate interference in muscle strength, power and hypertrophy. This review consolidates available literature investigating increased protein intake on rates of muscle protein synthesis, hypertrophy, strength and force/power adaptations following acute and chronic concurrent training. Acute concurrent exercise studies provide evidence for the significant stimulation of myofibrillar protein synthesis with protein compared to placebo ingestion. High protein intake can also augment increases in lean mass with chronic concurrent training, although these increases do not appear to translate into further improvements in strength adaptations. Similarly, the available evidence indicates protein intake twice the recommended intake and beyond does not rescue decrements in selective aspects of muscle force and power production with concurrent training.
Introduction Pea protein is an attractive non-animal derived protein source to support dietary protein requirements. However, while high in leucine, a low methionine content has been suggested to limit its anabolic potential. Mycoprotein has a complete amino acid profile which, at least in part, may explain its ability to robustly stimulate MyoPS rates. We hypothesised that an inferior post-exercise MyoPS response would be seen following ingestion of pea protein compared with mycoprotein, which would be (partially) rescued by blending the two sources. Methods Thirty-three healthy, young (age; 21±1 y, BMI; 24±1 kg٠m-2) and resistance trained participants received primed, continuous infusions of L-[ring-2H5]phenylalanine and completed a bout of whole-body resistance exercise before ingesting 25 g protein from mycoprotein (MYC, n=11), pea protein (PEA, n=11) or a blend (39% MYC, 61% PEA) of the two (BLEND, n=11). Blood and muscle samples were taken pre-, 2 h and 4 h post- exercise/protein ingestion to assess postabsorptive and postprandial post-exercise myofibrillar protein fractional synthetic rates (FSRs). Results Protein ingestion increased plasma essential amino acid and leucine concentrations (time effect; P<0.0001), but more rapidly in BLEND and PEA compared with MYC (time x condition interaction; P<0.0001). From similar postabsorptive values (MYC, 0.026±0.008%·h-1; PEA, 0.028±0.007%·h-1; BLEND, 0.026±0.006%·h-1), resistance exercise and protein ingestion increased myofibrillar FSRs (time effect; P<0.0001) over a 4 h postprandial period (MYC, 0.076±0.004%·h-1; PEA, 0.087±0.01%·h-1; BLEND, 0.085±0.01%·h-1), with no differences between groups (all; P>0.05). Conclusions These data show that all three non-animal derived protein sources have utility in supporting post-exercise muscle reconditioning.
ÖZET
Kuersetin ve Resveratrol Tüketiminin Elit Adölesan Atletizm Mesafe
Koşucularının Laktik Asit Düzeyleri ile Koşu Performansı Üzerine Etkilerinin
İncelenmesi
Bu çalışmanın amacı kuersetin ve resveratrol tüketiminin elit adölesan atletizm
mesafe koşucularının laktik asit düzeyleri ile koşu performansı üzerine etkilerinin
incelenmesidir.
Araştırmaya Isparta ilinde bulunan elit düzeyde atletizm ile ilgilenen 4 kadın
ve 4 erkek adölesan sporcu katılmıştır. Çalışmaya katılan elit adölesan atletlerin yaş
ortalamaları 16,13±2,03 yıl, sporcuların vücut ağırlığı ortalamaları 52,02±6,91 kg, boy
ortalamaları ise 168,3±10,61 cm olarak tespit edilmiştir. Adölesan sporcuların
performanslarına kuersetin ve resveratrolün etkisini ölçmek için çalışma birer hafta ara ile 3 hafta sürmüştür. Her haftanın belirlenen 2 günü kampa alınarak ilk hafta plasebo, ikinci hafta 500 mg kuersetin ve üçüncü hafta 100 mg resveratrol takviyeleri verilmiştir. Kampın ilk günü takviyesiz 1500 m koşmaları istenmiştir. Koşu öncesi ve sonrası laktik asit ölçümü alınmış ve koşu süreleri kaydedilmiştir. İkinci günü ise takviyeler verilerek aynı ölçümler tekrarlanmıştır. Araştırmada; lactate scout,
kronometre ve bioelektrik direnç ölçüm cihazı kullanılmıştır. Elde edilen verilerin
analizi için Paired – T Testi ve Korelasyon Testlerinden faydalanılmıştır, anlamlılık
düzeyi 0,05 olarak kabul edilmiştir.
Elde edilen bulgulara bakıldığında; Kuersetin takviyesinin akut etkisinin kadın
sporcularda biriken laktik asit seviyelerinde anlamlı düzeyde olduğu, erkeklerde ise
koşu süresinde fark oluşturmasına rağmen istatistiksel olarak anlamlı olmadığı,
resveratrol takviyesinde ise akut etkinin olmadığı dolayısıyla anlamlı bir sonuç
çıkmadığı tespit edilmiştir.
Sonuç olarak; kuersetin ve resveratrol müdahalelerinde yalnızca kuersetin
takviyesinin kadın elit adölesan atletlerde istatistiksel olarak anlamlı fark yarattığı
görülmüştür. Fakat istatistiksel olarak anlamlı çıkmasa da Atletizm spor dalı için çok
önemli olan koşu süresi farklılıkları ile karşılaşılmıştır. Dolayısıyla bu çalışmanın
özellikle kadın ve nispeten erkek sporcular için kuersetin takviyesinin laktik asit
seviyelerini azalttığı, yorgunluğun gecikmesini sağlayarak daha iyi bir performans
gösterebileceğini anlatan bir çalışma olduğu söylenebilmektedir.
Anahtar Kelimler: Kuersetin, Resveratrol, Laktik Asit, Yorgunluk, Sportif
Performans, Adölesan, Kadın Sporcular, Besin Takviyesi,
Atletizm
ABSTRACT
Investigation of the Effects of Quercetin and Resveratrol Consumption on
Lactic Acid Levels and Running Performance of Elite Adolescent Athletics
Distance Runners
The aim of this study is to investigate the effects of quercetin and resveratrol
consumption on the lactic acid levels and running performance of elite adolescent
athletics distance runners.
4 women and 4 male adolescent athletes interested in elite athletics in Isparta
province participated in the study. The average age of elite adolescent athletes
participating in the study was 16.13 ± 2.03 years, the average weight of athletes was 52.02 ± 6.91 kg, and the average height was 168.3 ± 10.61 cm. The study took 3 weeks, one week apart, to measure the effect of quercetin and resveratrol on the performance of adolescent athletes. The two days of each week were taken to the camp and the first week was given placebo, the second week was 500 mg quercetin and the third week was 100 mg resveratrol supplements. On the first day of the camp, they were asked to run 1500 m without reinforcement. Before and after the run, lactic acid measurement was taken and the running times were recorded. On the second day, the same measurements were repeated with supplements. In the study; lactate scout, stopwatch and bioelectric resistance measurement device were used. Paired - T Test and Correlation Tests were used for the analysis of the data obtained, the significance level was accepted as 0.05.
Considering the findings obtained; It has been determined that the acute
effect of quercetin supplement is significant in lactic acid levels accumulated in female athletes, although it is not statistically significant in males despite the difference in running time, and there is no significant result in resveratrol supplement due to the absence of acute effect.
As a result; In quercetin and resveratrol interventions, only quercetin
supplementation was found to make a statistically significant difference in female elite adolescent athletes. However, although not statistically significant, differences in running time, which are very important for Athletics sports branch, were encountered. Therefore, it can be said that this study is a study explaining that quercetin supplementation decreases lactic acid levels, especially for female and relatively male athletes, and provides a better performance by providing delay of fatigue.
Key Words: Quercetin, Resveratrol, Lactic Acid, Fatigue, Sporty Performance,
Adolescent, Women Athletes, Nutritional Supplement, Athletic
Collegiate athletes are valuable assets of the University. Their athletic performance requires a high level of competitiveness to achieve commendable record standing; thus, nutrition plays an important role. Their dietary habits and how knowledgeable they are about proper nutrition are the primary concern of this study that will probably affect their performance. The purpose of the study is to determine if there is a relationship between Dietary Habits and Nutritional Knowledge. Also, to investigate if these two variables serve as a predictor of Athletic Performance among selected UST collegiate athletes. The descriptive- Correlational design was used in the study. Respondents were identified using the purposive sampling technique and stratified random sampling. 100 Team A selected collegiate athletes from the University of Santo Tomas who participated in the UAAP Season '80 were surveyed and completed a Dietary Habits and Nutritional Knowledge Questionnaire developed by Paugh (2005). Data were analyzed using Regression and Pearson Correlation Coefficient at an alpha level of .05. The results revealed that respondents practiced good dietary habits and had a good knowledge of nutrition with a General Weighted Mean of 2.70 and 3.02, respectively. There is a significant relationship between dietary habits and nutritional knowledge. Dietary habit predicts athletic performance while nutritional knowledge does not predict athletic performance.The researchers highly recommend the full support/assistance of Coaches/Athletic Trainers/ Sports Conditioning Coach, and Parents in guiding the nutritional diet of student-athlete and the availability of Sport Dietician to implement a dietary plan for student-athletes to reach their optimal athletic performance.
Keywords: Dietary Habits, Nutritional Knowledge, Athletic Performance, Collegiate Athletes, Nutrition
This study investigated the aminoacidemia after ingestion of a poultry protein hydrolysate (PPH) and whey protein in healthy young and old participants. Protein-drinks were also digested using the INFOGEST static in vitro digestion model to simulate gastrointestinal changes in young and old adults. In fasted state, 10 young (20-40y) and 10 old (70-80y) ingested PPH or whey as a 20 g protein-drink and blood samples were collected. Plasma leucine concentration increased more when ingesting whey than PPH (young 62 ± 27 vs. 48 ± 27%, old 94 ± 57 vs. 66 ± 26%) but the peak concentration was reached faster after drinking PPH (p
Mass spectrometry has developed into a platform for the assessment of health, sensory, quality and safety aspects of food. Current nutrition research focuses on unravelling the link between acute or chronic dietary and nutrient intake and the physiological effects at cellular, tissue and whole body level. The bioavailability and bioefficacy of food constituents and dose-effect correlations are key to understanding the impact of food on defined health outcomes. To generate this information, appropriate analytical tools are required to identify and quantify minute amounts of individual compounds in highly complex matrices (such as food or biological fluids) and to monitor molecular changes in the body in a highly specific and sensitive manner. Mass spectrometry has become the method of choice for such work and now has broad applications throughout all areas of nutrition research. This book focuses the contribution of mass spectrometry to the advancement of nutrition research. Aimed at students, teachers and researchers, it provides a link between nutrition and analytical biochemistry. It guides nutritionists to the appropriate techniques for their work and introduces analytical biochemists to new fields of application in nutrition and health. The first part of the book is dedicated to the assessment of macro- and micro-nutrient status with a view to making dietary recommendations for the treatment of diet-related diseases. The second part shows how mass spectrometry has changed nutrition research in fields like energy metabolism, body composition, protein turnover, immune modulation and cardiovascular health.
Purpose
Exercise training plays an important role in maintaining the bone health and prevention of osteoporosis or age-related bone loss. Aerobic exercise, resistance exercise or a combination of both are used to maintain bone health. Mechanical loading induced by resistance exercise stimulates a number of mechanisms that help to maintain or improve bone mineral density. The present review article aims at summarizing the mechanisms and the use of resistance exercises for improving or maintaining the bone and muscle mass.
Methodology
Literature search was done using PubMed Central, CINAHL, sciencedirect.com with keywords resisted exercises, osteoporosis, postmenopausal and effect of resisted exercises in osteoporosis.
Results
Resistance exercises have a significant effect in maintaining the musculoskeletal health. Mechanical loading of the bone especially with high intensity exercises, leads to an improvement in the bone mineral density.
Conclusion
Resistance exercises may help to regulate the bone health and prevent the development of osteoporosis. These can be included in the exercise programmes designed for osteoporotic or postmenopausal patients.
This year’s 39th International Symposium on Diabetes and Nutrition in Anavyssos, Greece, hosted a series of presentations and plenary lectures with a focus on the effects of weight loss, micronutrients, nutritional supplements, and alternative dietary patterns in the prevention and management of Type 2 diabetes (T2D) and cardiovascular risk reduction. Michael Lean discussed how diabetes remission can be achieved through weight loss using a low-energy diet (LED) or very low-energy diet (VLED), accompanied by continued long-term support from specialised healthcare professionals. Jeffrey Mechanick discussed the importance and impact of early intervention on T2D and cardiovascular disease (CVD). He emphasised that T2D should be seen not just at the point of disease, but on a spectrum from prediabetes to complications, with early interventions having significant impact on not only the progression of T2D, but also into the latter stages.Simin Liu presented an integrative multilevel framework for causal inference to personalise cardiometabolic health, highlighting recent work investigating the roles of dietary minerals, environment metals, and genomics in relation to cardiovascular disease and diabetes. Several of the presentations included discussion of specific interventions. Daniel West discussed the use of whey protein (WP) and how it can help control postprandial glycaemic excursions (PGE) in people with T2D controlled on oral antihyperglycaemic drugs. Following this, Andrea Hawkinson discussed how a new supplement, mulberry leaf (Morus alba) extract (MLE), can significantly lower postprandial glucose response, as well as early insulin response, highlighting the need for further studies to evaluate its efficacy in people with T2D. Philip Atherton showed studies providing evidence that protein and essential amino acid (EAA) supplementation can help support muscle mass, which is especially essential for older people with T2D and sarcopenia. Finally, Jose-María López-Pedrosa spoke about how a supplement containing slow digestible carbohydrates (SDC), arginine, lysine, and β-hydroxy-β-methylbutyric acid (HMB) can help preserve muscle mass, as well as improve insulin resistance, in a rat model of diabetes.
Maintaining muscle quality throughout life is crucial to human health and well-being. Muscle is the most extensive form of protein storage in the human body; skeletal muscle mass is determined by the balance between muscle protein synthesis (MPS) and muscle protein breakdown (MPB). MPB provides amino acids needed by various organs; however, excessive MPB, especially with aging, may cause loss of muscle mass and a decline in motor function, even threatening life. The turnover of muscle protein is vital to the health of humans. Thus, while the study of MPS and MPB has theoretical and practical significance, the network that controls MPS is very complicated and we cannot discuss both MPS and MPB in a single review. Therefore, this review mainly discusses the regulation of MPS, especially by amino acids. Amino acids regulate protein synthesis in cell and animal models, but compelling evidence for amino acids promoting protein synthesis in human muscles is ambiguous. In particular, studies on the stimulation of human MPS by branched-chain amino acids (BCAAs) have been inconsistent. Amino acids other than BCAAs such as threonine and tryptophan may also have MPS-stimulating effects, and alternatives to BCAAs, such as Beta-Hydroxy-Beta-Methyl butyrate (HMB) and branched-chain ketoacids (BCKAs) are also worthy of further investigation explore. Amino acids coordinate protein synthesis and degradation through the mechanistic target of rapamycin complex 1 (mTORC1); however, the amino acid-mTORC1-protein synthesis pathway is complex, and new insights into amino acid control continue to emerge. Understanding how amino acids control MPS is of forward-looking significance for treating muscle mass loss during human aging.
Background:
Protein intake plays an important role in the synthesis and maintenance of skeletal muscles for the prevention of health risks. It is also widely known that physical activity influences muscle function. However, no large-scale studies have examined the relationship between daily dietary habits, especially the timing of protein intake, and daily physical activity.
Objective:
The purpose of this cross-sectional study was to investigate how protein intake and composition (involving the 3 major nutrients protein, fat, and carbohydrate) in the 3 traditional meals (breakfast, lunch, and dinner) are associated with physical activity.
Methods:
Using daily dietary data accumulated in the smartphone food log app "Asken" and a web-based cross-sectional survey involving Asken users (N=8458), we analyzed nutrient intake and composition, as well as daily activity levels. As very few individuals skipped breakfast (1102/19,319 responses, 5.7%), we analyzed data for 3 meals per day.
Results:
Spearman rank correlation analysis revealed that breakfast and lunch protein intakes had higher positive correlations with daily physical activity among the 3 major macronutrients (P<.001). These findings were confirmed by multivariate logistic regression analysis with confounding factors. Moreover, participants with higher protein intake and composition at breakfast or lunch tended to exhibit significantly greater physical activity than those with higher protein intake at dinner (P<.001).
Conclusions:
Among the 3 macronutrients, protein intake during breakfast and lunch was closely associated with daily physical activity.
Bodybuilding involves an intricate combination of training and dieting focused around periodic mesocycles to tailor time towards preparation and competition. In contrast to other muscle sports (such as weightlifting and powerlifting), bodybuilding competitors are judged on appearance (muscle size, definition and posing) as opposed to physical performance. Professional competitors achieve this by altering training variables (such as intensity and volume) as well as dietary and supplementation strategies throughout the 'season'. These mesocycles follow protocols based on a scientific literature, with the intention to achieve better results and preserve the health of each competitor. In order to achieve the long term improvements to health and skill-related components of fitness, a programme and strategy must be implemented that incorporates components of both dietary restriction as well as systematic variations to training and exercise selection. Because of the nature of body aesthetics and muscularity in bodybuilding, off-season training follows hypertrophic goals to increase muscular size. Increased caloric intake as well as increased training volume and intensity are the most common adaptations to a hypertrophic mesocycle. A positive energetic caloric balance (~10-20%) and high protein consumption provide necessary nutrients for muscle protein synthesis and energy storage and usage. During any cycle, weight gain and loss should not surpass 5% bodyweight per week to reduce the health concerns associated with rapid weight fluctuations. Current literature suggests that macronutrient intakes of protein 1.6-2.2 g•kg-1 •d-1 (25-30% TDC), carbohydrates 5-6 g•kg-1 •d-1 (50-60% TDC) and fat 1-1.5 g•kg-1 •d-1 (20-25% TDC) are suggested as optimal for professional bodybuilders to meet the physiological needs of an off-season mesocycle focusing on lean muscle gain. Bodybuilding • Nutrition • Hypertrophy • Performance • Physique
Original Article Abstract Purpose: Recently, the use of resistance training with restricted blood flow (BFR) has been recommended as an alternative to heavy resistance training for middle-aged and elderly people. Therefore, the aim of this research was to determine the effect of resistance training with and without BFR on levels of anabolic and catabolic hormones in middle-age sedentary male. Methods: In this semi-experimental study design, 20 voluntary middle-aged sedentary men (age 47.65 ± 2.53 years) were selected. Subjects were randomly divided into two groups of resistance training with and without BFR. Subjects in the 4-week BFR group performed knee extension and leg press at 20% 1-RM intensity, one set of 30 repetitions and two sets of 15 repetitions, and the non-BFR training group performed the same movements at 80% 1-RM intensity in three sets with 10 repetitions. Blood samples were also taken to measure testosterone and cortisol, growth hormone and insulin-like growth factor-1. Finally, Data were analyzed by analyses of variance and independent T test. The significance level was set at P < 0.05. Results: Resting concentrations of growth hormone (P = 0.001), IGF-I (P = 0.001), and serum testosterone (P = 0.001) response increased significantly after four weeks of resistance training. Also, the only increase in resting growth hormone was significantly higher in the BFR group (P = 0.04). However, four weeks of resistance training with (P = 0.11) and without Restricted blood flow (P = 0.55) did not significantly change cortisol concentration. Conclusion: It seems likely that performing resistance training with BFR during middle age is a good way to achieve the health benefits of exercise training due to hormonal adaptations. How to cite this article: Vakili J, Nikookheslat S, Pakzad Hassanlou F. The effect of four weeks of resistance training with and without blood flow restriction on levels of anabolic and catabolic hormonal markers in middle-age sedentary males. Journal of Sport and Exercise Physiology 2022;15(1):45-56
Background
The physical and functional outcomes of lifelong treatment with a phenylalanine restricted diet for the management of Phenylketonuria (PKU) remain unknown. Given that the mainstay of dietary management consists of modifying the sources of ingested protein, various aspects of body protein status could be compromised.
Objectives
To examine the existing evidence regarding the protein status of people with PKU and identify nutritional and lifestyle variables that influence protein status.
Eligibility criteria
Studies reporting anthropometric, biochemical and/or functional measurements of body protein status in people with PKU were eligible.
Source of evidence
MEDLINE (Ovid), Embase (Ovid), CENTRAL, Web of Science and Scopus, and conference abstracts.
Results
Seventy studies were included in the review. The majority of studies assessing protein status based on anthropometric measurements observed no differences between people with PKU and controls, although deficits in muscle mass were reported within PKU cohorts. Findings for biochemical assessment of protein status were mixed and limited studies assessed protein status using functional measures. Factors such as participant age, sex, metabolic control, protein source, type of protein substitute, and pharmacological treatments were found to modulate protein status of people with PKU.
Conclusions
Findings were inconclusive regarding body protein status in people with PKU. The relationship between diet and protein status outcomes remains unclear and further research is warranted to determine the impact of dietary regimens on physical and functional outcomes, and to understand the best clinical assessments to reliably monitor the protein status in people with PKU.
Pre-sleep protein intake is a topic that has been studied frequently in the recent years. Protein taken before sleep is thought to be effectively digested and absorbed during nighttime sleep, thus increasing the muscle protein synthesis rate during the night. The effects of pre-sleep protein intake are substantial, as physically active individuals and athletes want to maximize their physiological adaptation and improve their performance. The purpose of the present review is to examine the current studies on muscle protein synthesis, muscle mass and strength of pre-sleep protein intake, and provide up-to-date and complementary information on the subject by summarizing the acute and chronic effects.
Background: Resistance exercise leads to net muscle protein accretion through a synergistic interaction of exercise and feeding. Proteins from different sources may differ in their ability to support muscle protein accretion because of different patterns of postprandial hyperaminoacidemia.
Objective: We examined the effect of consuming isonitrogenous, isoenergetic, and macronutrient-matched soy or milk beverages (18 g protein, 750 kJ) on protein kinetics and net muscle protein balance after resistance exercise in healthy young men. Our hypothesis was that soy ingestion would result in larger but transient hyperaminoacidemia compared with milk and that milk would promote a greater net balance because of lower but prolonged hyperaminoacidemia.
Design: Arterial-venous amino acid balance and muscle fractional synthesis rates were measured in young men who consumed fluid milk or a soy-protein beverage in a crossover design after a bout of resistance exercise.
Results: Ingestion of both soy and milk resulted in a positive net protein balance. Analysis of area under the net balance curves indicated an overall greater net balance after milk ingestion (P < 0.05). The fractional synthesis rate in muscle was also greater after milk consumption (0.10 ± 0.01%/h) than after soy consumption (0.07 ± 0.01%/h; P = 0.05).
Conclusions: Milk-based proteins promote muscle protein accretion to a greater extent than do soy-based proteins when consumed after resistance exercise. The consumption of either milk or soy protein with resistance training promotes muscle mass maintenance and gains, but chronic consumption of milk proteins after resistance exercise likely supports a more rapid lean mass accrual.
The speed of absorption of dietary amino acids by the gut varies according to the type of ingested dietary protein. This could
affect postprandial protein synthesis, breakdown, and deposition. To test this hypothesis, two intrinsically 13C-leucine-labeled milk proteins, casein (CAS) and whey protein (WP), of different physicochemical properties were ingested
as one single meal by healthy adults. Postprandial whole body leucine kinetics were assessed by using a dual tracer methodology.
WP induced a dramatic but short increase of plasma amino acids. CAS induced a prolonged plateau of moderate hyperaminoacidemia,
probably because of a slow gastric emptying. Whole body protein breakdown was inhibited by 34% after CAS ingestion but not
after WP ingestion. Postprandial protein synthesis was stimulated by 68% with the WP meal and to a lesser extent (+31%) with
the CAS meal. Postprandial whole body leucine oxidation over 7 h was lower with CAS (272 ± 91 μmol⋅kg−1) than with WP (373 ± 56 μmol⋅kg−1). Leucine intake was identical in both meals (380 μmol⋅kg−1). Therefore, net leucine balance over the 7 h after the meal was more positive with CAS than with WP (P < 0.05, WP vs. CAS). In conclusion, the speed of protein digestion and amino acid absorption from the gut has a major effect
on whole body protein anabolism after one single meal. By analogy with carbohydrate metabolism, slow and fast proteins modulate
the postprandial metabolic response, a concept to be applied to wasting situations.
Six men were studied to determine the interrelationships among blood supply, motor unit (MU) activity and lactate concentrations during intermittent isometric contractions of the hand grip muscles. The subjects performed repeated contractions at 20% of maximal voluntary contraction (MVC) for 2 s followed by 2-s rest for 4 min with either unhindered blood circulation or arterial occlusion given between the 1st and 2nd min. The simultaneously recorded intramuscular MU spikes and surface electromyogram (EMG) data indicated that mean MU spike amplitude, firing frequency and the parameters of surface EMG power spectra (mean power frequency and root mean square amplitude) remained constant during the experiment with unhindered circulation, providing no electrophysiological signs of muscle fatigue. Significant increases in mean MU spike amplitude and frequency were, however, evident during the contractions with arterial occlusion. Similar patterns of significant changes in the surface EMG spectra parameters and venous lactate concentration were also observed, while the integrated force-time curves remained constant. These data would suggest that the metabolic state of the active muscles may have played an important role in the regulation of MU recruitment and rate coding patterns during exercise.
The nature of the deficit underlying age-related muscle wasting remains controversial. To test whether it could be due to a poor anabolic response to dietary amino acids, we measured the rates of myofibrillar and sarcoplasmic muscle protein synthesis (MPS) in 44 healthy young and old men, of similar body build, after ingesting different amounts of essential amino acids (EAA). Basal rates of MPS were indistinguishable, but the elderly showed less anabolic sensitivity and responsiveness of MPS to EAA, possibly due to decreased intramuscular expression, and activation (phosphorylation) after EAA, of amino acid sensing/signaling proteins (mammalian target of rapamycin, mTOR; p70 S6 kinase, or p70(S6k); eukaryotic initiation factor [eIF]4BP-1; and eIF2B). The effects were independent of insulin signaling since plasma insulin was clamped at basal values. Associated with the anabolic deficits were marked increases in NFkappaB, the inflammation-associated transcription factor. These results demonstrate first, EAA stimulate MPS independently of increased insulin availability; second, in the elderly, a deficit in MPS in the basal state is unlikely; and third, the decreased sensitivity and responsiveness of MPS to EAA, associated with decrements in the expression and activation of components of anabolic signaling pathways, are probably major contributors to the failure of muscle maintenance in the elderly. Countermeasures to maximize muscle maintenance should target these deficits.
Muscle growth is associated with an activation of the mTOR signaling pathway and satellite cell regulators. The purpose of this study was to determine whether 17 selected genes associated with mTOR/muscle protein synthesis and the satellite cells/myogenic program are differentially expressed in young and older human skeletal muscle at rest and in response to a potent anabolic stimulus [resistance exercise + essential amino acid ingestion (RE+EAA)]. Twelve male subjects (6 young, 6 old) completed a bout of heavy resistance exercise. Muscle biopsies were obtained before and at 3 and 6 h post RE+EAA. Subjects ingested leucine-enriched essential amino acids at 1 h postexercise. mRNA expression was determined using qRT-PCR. At rest, hVps34 mRNA was elevated in the older subjects (P < 0.05) while there was a tendency for levels of myoD, myogenin, and TSC2 mRNA to be higher than young. The anabolic stimulus (RE+EAA) altered mRNAs associated with mTOR regulation. Notably, REDD2 decreased in both age groups (P < 0.05) but the expression of Rheb mRNA increased only in the young. Finally, cMyc mRNA was elevated (P < 0.05) in both young and old at 6 h post RE+EAA. Furthermore, RE+EAA also increased expression of several mRNAs associated with satellite function in the young (P < 0.05), while expression of these mRNAs did not change in the old. We conclude that several anabolic genes in muscle are more responsive in young men post RE+EAA. Our data provide new insights into the regulation of genes important for transcription and translation in young and old human skeletal muscle post RE+EAA.
The purpose of this study was to investigate the magnitude and time course for changes in muscle protein synthesis (MPS) after a single bout of resistance exercise. Two groups of six male subjects performed heavy resistance exercise with the elbow flexors of one arm while the opposite arm served as a control. MPS from exercised (ex) and control (con) biceps brachii was assessed 4 (group A) and 24 h (group B) postexercise by the increment in L-[1-13C]leucine incorporation into muscle biopsy samples. In addition, RNA capacity and RNA activity were determined to assess whether transcriptional and/or translational processes affected MPS. MPS was significantly elevated in biceps of the ex compared with the con arms of both groups (group A, ex 0.1007 +/- 0.0330 vs. con 0.067 +/- 0.0204%/h; group B ex 0.0944 +/- 0.0363 vs. con 0.0452 +/- 0.0126%/h). RNA capacity was unchanged in the ex biceps of both groups relative to the con biceps, whereas RNA activity was significantly elevated in the ex biceps of both groups (group A, ex 0.19 +/- 0.10 vs. con 0.12 +/- 0.05 micrograms protein.h-1.microgram-1 total RNA; group B, ex 0.18 +/- 0.06 vs. con 0.08 +/- 0.02 micrograms protein.h-1.microgram-1 total RNA). The results indicate that a single bout of heavy resistance exercise can increase biceps MPS for up to 24 h postexercise. In addition, these increases appear to be due to changes in posttranscriptional events.
Previous studies using indirect means to assess the response of protein metabolism to exercise have led to conflicting conclusions. Therefore, in this study we have measured the rate of muscle protein synthesis in normal volunteers at rest, at the end of 4 h of aerobic exercise (40% maximal O2 consumption), and after 4 h of recovery by determining directly the rate of incorporation of 1,2-[13C]leucine into muscle. The rate of muscle protein breakdown was assessed by 3-methylhistidine (3-MH) excretion, and total urinary nitrogen excretion was also measured. There was an insignificant increase in 3-MH excretion in exercise of 37% and a significant increase (P less than 0.05) of 85% during 4 h of recovery from exercise (0.079 +/- 0.008 vs. 0.147 +/- 0.0338 mumol.kg-1.min-1 for rest and recovery from exercise, respectively). Nonetheless, there was no effect of exercise on total nitrogen excretion. Muscle fractional synthetic rate was not different in the exercise vs. the control group at the end of exercise (0.0417 +/- 0.004 vs. 0.0477 +/- 0.010%/h for exercise vs. control), but there was a significant increase in fractional synthetic rate in the exercise group during the recovery period (0.0821 +/- 0.006 vs. 0.0654 +/- 0.012%/h for exercise vs. control, P less than 0.05). Thus we conclude that although aerobic exercise may stimulate muscle protein breakdown, this does not result in a significant depletion of muscle mass because muscle protein synthesis is stimulated in recovery.
Muscle biopsies of the vastus lateralis muscle taken before and after 18 weeks of resistance training were compared by preparing frozen cross sections for electron microscopy and using adjacent sections for fiber typing by myosin ATPase activity. Quantitative ultrastructural changes were observed in histochemically-identified muscle fiber types of twelve young women who underwent the training. The percentage of type IIB fibers decreased and IIA fibers increased. The cross-sectional area of all major fiber types increased with training. The absolute volume of myofibrils, intermyofibrillar space, and mitochondria increased with training for most major fiber types (type I, IIA and IIAB), but the relative volume percentages were not significantly changed because of corresponding fiber hypertrophy. Mean mitochondrial size for types I and IIA and myofibril size for types IIC and IIB increased significantly with training. The capillary number per fiber and density did not change with training. Activity levels were measured for selected glycolytic and oxidative enzymes. Cytochrome oxidase and hexokinase increased significantly with training, while creatine kinase, citrate synthase, phosphofructokinase, glyceraldehyde phosphate dehydrogenase and hydroxyacyl CoA dehydrogenase enzymes were not significantly altered. The results suggest that this type of high-repetition resistance training causes the intracellular components of all fiber types to increase proportionally with an increase in fiber size. In addition, the enzyme analysis indicates the muscle as a whole may increase its oxidative phosphorylation capacity in conjunction with the decreased percentage of type IIB fibers.
It has been shown that muscle protein synthetic rate (MPS) is elevated in humans by 50% at 4 hrs following a bout of heavy resistance training, and by 109% at 24 hrs following training. This study further examined the time course for elevated muscle protein synthesis by examining its rate at 36 hrs following a training session. Six healthy young men performed 12 sets of 6- to 12-RM elbow flexion exercises with one arm while the opposite arm served as a control. MPS was calculated from the in vivo rate of incorporation of L-[1,2-13C2] leucine into biceps brachii of both arms using the primed constant infusion technique over 11 hrs. At an average time of 36 hrs postexercise, MPS in the exercised arm had returned to within 14% of the control arm value, the difference being nonsignificant. It is concluded that following a bout of heavy resistance training, MPS increases rapidly, is more than double at 24 hrs, and thereafter declines rapidly so that at 36 hrs it has almost returned to baseline.
We investigated the effects of the nature of the flooding amino acid on the rate of incorporation of tracer leucine into human skeletal muscle sampled by biopsy. Twenty-three healthy young men (24.5 +/- 5. 0 yr, 76.2 +/- 8.3 kg) were studied in groups of four or five. First, the effects of flooding with phenylalanine, threonine, or arginine (all at 0.05 g/kg body wt) on the incorporation of tracer [13C]leucine were studied. Then the effects of flooding with labeled [13C]glycine [0.1 g/kg body wt, 20 atoms percent excess (APE)] and [13C]serine (0.05 g/kg body wt, 15 APE) on the incorporation of simultaneously infused [13C]leucine were investigated. When a large dose of phenylalanine or threonine was administered, incorporation of the tracer leucine was significantly increased (from 0.036 to 0. 067 %/h and 0.037 to 0.070 %/h, respectively; each P < 0.01). However, when arginine, glycine, or serine was administered as a flooding dose, no stimulation of tracer leucine incorporation could be observed. These results, together with those previously obtained, suggest that large doses of individual essential, but not nonessential, amino acids are able to stimulate incorporation of constantly infused tracer amino acids into human muscle protein.
The results of several recent studies indicate that bradykinin protects tissues against the deleterious effects of ischemia-reperfusion (I/R). However, other studies indicate that bradykinin can act as a proinflammatory agent, inducing P-selectin expression, the formation of chemotactic stimuli, and endothelial barrier disruption. In the present study, we used intravital microscopic techniques to examine the dose-dependent effects of bradykinin on leukocyte-endothelial cell interactions, the formation of platelet-leukocyte aggregates, and venular hemodynamics in rat mesentery in an attempt to explain these divergent findings. Superfusion of the mesentery with low concentrations of bradykinin (</=10(-7) M) increased venular erythrocyte velocity (V(RBC)) without increasing the number of adherent leukocytes, whereas higher concentrations (>/=10(-6) M) decreased V(RBC), increased the number of platelet-leukocyte aggregates, and induced leukocyte adhesion in single postcapillary venules. The formation of platelet-leukocyte aggregates and increased leukocyte adhesion induced by high-dose bradykinin were attenuated by administration of a B(2)-receptor (HOE-140) or a platelet-activating factor (PAF, WEB-2086) antagonist. Thus these adhesive interactions induced by high-dose bradykinin appear to be mediated by a mechanism that is dependent on B(2)-receptor activation and the formation of PAF or PAF-like lipids. The effects of bradykinin on venular V(RBC) and blood flow were also concentration dependent, with low doses producing nitric oxide-mediated vasodilation, whereas high doses decreased V(RBC) by a mechanism that is PAF independent.
Acute and long-term effects of resistance exercise combined with vascular occlusion on muscular function were investigated. Changes in integrated electromyogram with respect to time (iEMG), vascular resistive index, and plasma lactate concentration were measured in five men either during or after elbow flexion exercises with the proximal end of the arm occluded at 0-100 mmHg. The mean iEMG, postexercise hyperemia, and plasma lactate concentration were all elevated with the increase in occlusion pressure at a low-intensity exercise, whereas they were unchanged with the increase in occlusion pressure at high-intensity exercise. To investigate the long-term effects of low-intensity exercise with occlusion, older women (n = 24) were subjected to a 16-wk exercise training for elbow flexor muscles, in which low-intensity [ approximately 50-30% one repetition maximum (1 RM)] exercise with occlusion at approximately 110 mmHg (LIO), low-intensity exercise without occlusion (LI), and high- to medium-intensity ( approximately 80-50% 1 RM) exercise without occlusion (HI) were performed. Percent increases in both cross-sectional area and isokinetic strength of elbow flexor muscles after LIO were larger than those after LI (P < 0.05) and similar to those after HI. The results suggest that resistance exercise at an intensity even lower than 50% 1 RM is effective in inducing muscular hypertrophy and concomitant increase in strength when combined with vascular occlusion.
To evaluate the importance of protein digestion rate on protein deposition, we characterized leucine kinetics after ingestion of "protein" meals of identical amino acid composition and nitrogen contents but of different digestion rates. Four groups of five or six young men received an L-[1-13C]leucine infusion and one of the following 30-g protein meals: a single meal of slowly digested casein (CAS), a single meal of free amino acid mimicking casein composition (AA), a single meal of rapidly digested whey proteins (WP), or repeated meals of whey proteins (RPT-WP) mimicking slow digestion rate. Comparisons were made between "fast" (AA, WP) and "slow" (CAS, RPT-WP) meals of identical amino acid composition (AA vs. CAS, and WP vs. RPT-WP). The fast meals induced a strong, rapid, and transient increase of aminoacidemia, leucine flux, and oxidation. After slow meals, these parameters increased moderately but durably. Postprandial leucine balance over 7 h was higher after the slow than after the fast meals (CAS: 38 +/- 13 vs. AA: -12 +/- 11, P < 0.01; RPT-WP: 87 +/- 25 vs. WP: 6 +/- 19 micromol/kg, P < 0.05). Protein digestion rate is an independent factor modulating postprandial protein deposition.
The present study was designed to determine whether consumption of an oral essential amino acid-carbohydrate supplement (EAC) before exercise results in a greater anabolic response than supplementation after resistance exercise. Six healthy human subjects participated in two trials in random order, PRE (EAC consumed immediately before exercise), and POST (EAC consumed immediately after exercise). A primed, continuous infusion of L-[ring-(2)H(5)]phenylalanine, femoral arteriovenous catheterization, and muscle biopsies from the vastus lateralis were used to determine phenylalanine concentrations, enrichments, and net uptake across the leg. Blood and muscle phenylalanine concentrations were increased by approximately 130% after drink consumption in both trials. Amino acid delivery to the leg was increased during exercise and remained elevated for the 2 h after exercise in both trials. Delivery of amino acids (amino acid concentration times blood flow) was significantly greater in PRE than in POST during the exercise bout and in the 1st h after exercise (P < 0.05). Total net phenylalanine uptake across the leg was greater (P = 0.0002) during PRE (209 +/- 42 mg) than during POST (81 +/- 19). Phenylalanine disappearance rate, an indicator of muscle protein synthesis from blood amino acids, increased after EAC consumption in both trials. These results indicate that the response of net muscle protein synthesis to consumption of an EAC solution immediately before resistance exercise is greater than that when the solution is consumed after exercise, primarily because of an increase in muscle protein synthesis as a result of increased delivery of amino acids to the leg.
We used a previously developed compartmental model to assess the postprandial distribution and metabolism of dietary nitrogen (N) in the splanchnic and peripheral areas after the ingestion of a single mixed meal containing either (15)N-labeled milk or soy purified protein. Although the lower whole-body retention of dietary N from soy protein was measured experimentally, the splanchnic retention of dietary N was predicted by the model not to be affected by the protein source, and its incorporation into splanchnic proteins was predicted to reach approximately 35% of ingested N at 8 h after both meals. However, dietary N intestinal absorption and its appearance in splanchnic free amino acids were predicted to be more rapid from soy protein and were associated with a higher deamination, concomitant with a higher efficiency of incorporation of dietary N into proteins in the splanchnic bed. In contrast, soy protein was predicted to cause a reduction in peripheral dietary N uptake, as a consequence of both similar splanchnic retention and increased oxidation compared with milk protein. In addition, protein synthesis efficiency was reduced in the peripheral area after soy protein intake, leading to dietary N incorporation in peripheral proteins that fell from 26 to 19% of ingested N 8 h after milk and soy protein ingestion, respectively. Such a model thus enables a description of the processes involved in the differential metabolic utilization of dietary proteins and constitutes a valuable tool for further definition of the notion of protein quality during the period of protein gain.
The effects of resistance exercise combined with vascular occlusion on muscle function were investigated in highly trained athletes. Elite rugby players (n = 17) took part in an 8 week study of exercise training of the knee extensor muscles, in which low-intensity [about 50% of one repetition maximum] exercise combined with an occlusion pressure of about 200 mmHg (LIO, n = 6), low-intensity exercise without the occlusion (LI, n = 6), and no exercise training (untrained control, n = 5) were included. The exercise in the LI group was of the same intensity and amount as in the LIO group. The LIO group showed a significantly larger increase in isokinetic knee extension torque than that in the other two groups (P < 0.05) at all the velocities studied. On the other hand, no significant difference was seen between LI and the control group. In the LIO group, the cross-sectional area of knee extensors increased significantly (P < 0.01), suggesting that the increase in knee extension strength was mainly caused by muscle hypertrophy. The dynamic endurance of knee extensors estimated from the decreases in mechanical work production and peak force after 50 repeated concentric contractions was also improved after LIO, whereas no significant change was observed in the LI and control groups. The results indicated that low-intensity resistance exercise causes, in almost fully trained athletes, increases in muscle size, strength and endurance, when combined with vascular occlusion.
Background:
The progressive loss of skeletal muscle mass with aging is attributed to a disruption in the regulation of skeletal muscle protein turnover.
Objective:
We investigated the effects on whole-body protein balance and mixed-muscle protein synthesis rates of the ingestion of carbohydrate with or without protein and free leucine after simulated activities of daily living.
Design:
Eight elderly (75 +/- 1 y) and 8 young (20 +/- 1 y) lean men were randomly assigned to 2 crossover experiments in which they consumed either carbohydrate (CHO) or carbohydrate plus protein and free leucine (CHO+Pro+Leu) after performing 30 min of standardized activities of daily living. Primed, continuous infusions with L-[ring-13C6]phenylalanine and L-[ring-2H2]tyrosine were applied, and blood and muscle samples were collected to assess whole-body protein turnover and the protein fractional synthetic rate in the vastus lateralis muscle over a 6-h period.
Results:
Whole-body phenylalanine and tyrosine flux were significantly higher in the young than in the elderly men (P < 0.01). Protein balance was negative in the CHO experiment but positive in the CHO+Pro+Leu experiment in both groups. Mixed-muscle protein synthesis rates were significantly greater in the CHO+Pro+Leu than in the CHO experiment in both the young (0.082 +/- 0.005%/h and 0.060 +/- 0.005%/h, respectively; P < 0.01) and the elderly (0.072 +/- 0.006%/h and 0.043 +/- 0.003%/h, respectively; P < 0.01) subjects, with no significant differences between groups.
Conclusions:
Co-ingestion of protein and leucine with carbohydrate after activities of daily living improves whole-body protein balance, and the increase in muscle protein synthesis rates is not significantly different between lean young and elderly men.
Resistance exercise is fundamentally anabolic and as such stimulates the process of skeletal muscle protein synthesis (MPS) in an absolute sense and relative to skeletal muscle protein breakdown (MPB). However, the net effect of resistance exercise is to shift net protein balance (NPB = MPS - MPB) to a more positive value; however, in the absence of feeding NPB remains negative. Feeding stimulates MPS to an extent where NPB becomes positive, for a transient time. When combined, resistance exercise and feeding synergistically interact to result in NPB being greater than with feeding alone. This feeding- and exercise-induced stimulation of NPB is what, albeit slowly, results in muscle hypertrophy. With this rudimentary knowledge we are now at the point where we can manipulate variables within the system to see what impact these interventions have on the processes of MPS, MPB, and NPB and ultimately and perhaps most importantly, muscle hypertrophy and strength. We used established models of skeletal muscle amino acid turnover to examine how protein source (milk versus soy) acutely affects the processes of MPS and MPB after resistance exercise. Our findings revealed that even when balanced quantities of total protein and energy are consumed that milk proteins are more effective in stimulating amino acid uptake and net protein deposition in skeletal muscle after resistance exercise than are hydrolyzed soy proteins. Importantly, the finding of increased amino acid uptake would be independent of the differences in amino acid composition of the two proteins. We propose that the improved net protein deposition with milk protein consumption is also not due to differences in amino acid composition, but is due to a different pattern of amino acid delivery associated with milk versus hydrolyzed soy proteins. If our acute findings are accurate then we hypothesized that chronically the greater net protein deposition associated with milk protein consumption post-resistance exercise would eventually lead to greater net protein accretion (i.e., muscle fiber hypertrophy), over a longer time period. In young men completing 12 weeks of resistance training (5d/wk) we observed a tendency (P = 0.11) for greater gains in whole body lean mass and whole as greater muscle fiber hypertrophy with consumption of milk. While strength gains were not different between the soy and milk-supplemented groups we would argue that the true significance of a greater increase in lean mass that we observed with milk consumption may be more important in groups of persons with lower initial lean mass and strength such as the elderly.
Muscle mass declines with aging. Amino acids alone stimulate muscle protein synthesis in the elderly. However, mixed nutritional supplementation failed to improve muscle mass. We hypothesized that the failure of nutritional supplements is due to altered responsiveness of muscle protein anabolism to increased amino acid availability associated with endogenous hyperinsulinemia. We measured muscle protein synthesis and breakdown, and amino acid transport in healthy young (30 +/- 3 yr) and elderly (72 +/- 1 yr) volunteers in the basal postabsorptive state and during the administration of an amino acid-glucose mixture, using L-[ring-(2)H(5)]phenylalanine infusion, femoral artery and vein catheterization, and muscle biopsies. Basal muscle amino acid turnover was similar in young and elderly subjects. The mixture increased phenylalanine leg delivery and transport into the muscle in both groups. Phenylalanine net balance increased in both groups (young, -27 +/- 8 to 64 +/- 17; elderly, -16 +/- 4 to 29 +/- 7 nmol/(min.100 mL); P: < 0.0001, basal vs. mixture), but the increase was significantly blunted in the elderly (P: = 0.030 vs. young). Muscle protein synthesis increased in the young, but remained unchanged in the elderly [young, 61 +/- 17 to 133 +/- 30 (P: = 0. 005); elderly, 62 +/- 9 to 70 +/- 14 nmol/(min.100 mL) (P: = NS)]. In both groups, protein breakdown decreased (P: = 0.012) and leg glucose uptake increased (P: = 0.0258) with the mixture. We conclude that the response of muscle protein anabolism to hyperaminoacidemia with endogenous hyperinsulinemia is impaired in healthy elderly due to the unresponsiveness of protein synthesis.
J Physiol 2001 August 15: 535(1): 301–11(1) Age-associated loss of skeletal muscle mass and strength can partly be counteracted by resistance training, causing a net synthesis of muscular proteins. Protein synthesis is influenced synergistically by post-exercise amino acid supplementation, but the importance of the timing of protein intake remains unresolved. (2) The study investigated the importance of immediate (P0) or delayed (P2) intake of an oral protein supplement upon muscle hypertrophy and strength over a period of resistance training in elderly males. (3) Thirteen men (age 74 ± 1 years; body mass index (BMI), 25 ± 1 kg m- 2 (means ± SEM)) completed a 12-week resistance training program (three times per week) receiving oral protein in liquid form (10 g protein, 7 g carbohydrate, 3 g fat) immediately after (P0) or 2 h after (P2) each training session. Muscle hypertrophy was evaluated by magnetic resonance imaging (MRI) and from muscle biopsies and muscle strength was determined using dynamic and isokinetic strength measurements. Body composition was determined from dual-energy X-ray absorptiometry (DEXA) and food records were obtained over 4 days. The plasma insulin response to protein supplementation was also determined. (4) In response to training, the cross-sectional area of m. quadriceps femoris (54.6 ± 0.5–58.3 ± 0.5 cm2) and mean fiber area (4047 ± 320–5019 ± 615 μ m2) increased in the P0 group, whereas no significant increase was observed in P2. For P0 both dynamic and isokinetic strength increased, by 46 and 15%, respectively (P P
In 1969, Pozefsky et al. ([8][1]) reported on the effects of systemic insulin infusion on forearm amino acid and glucose uptake. They noted that a large increase in insulin from 12 to 157 μU/ml resulted in a significant lowering of forearm (muscle) “…alpha amino nitrogen release by 74%…
The present study was performed to test the hypothesis that orally administered essential amino acids, in combination with carbohydrate, will stimulate net muscle protein synthesis in resting human muscle in vivo. Four volunteers ingested 500 mL of a solution containing 13.4 g of essential amino acids and 35 g sucrose (EAA). Blood samples were taken from femoral arterial and venous catheters over a 2-hour period following the ingestion of EAA to measure arteriovenous concentrations of amino acids across the muscle. Two muscle biopsies were taken during the study, one before administration of the drink and one approximately 2 hours after consumption of EAA. Serum insulin increased from normal physiologic levels at baseline (9.2 +/- 0.8 microU/mL) and peaked (48 +/- 7.1 microU/mL) 30 minutes after EAA ingestion. Arterial essential amino acid concentrations increased approximately 100 to 400% above basal levels between 10 and 30 minutes following drink ingestion. Net nitrogen (N) balance changed from negative (-495 +/- 128 nmol/mL) prior to consumption of EAA to a peak positive value (416 +/- 140 nmol/mL) within 10 minutes of ingestion of the drink. EAA resulted in an estimated positive net N uptake of 307.3 mg N above basal levels over the 2-hour period. Muscle amino acid concentrations were similar prior to and 2 hours following ingestion of EAA. We conclude that ingestion of a solution composed of carbohydrates to stimulate insulin release and a small amount of essential amino acids to increase amino acid availability for protein synthesis is an effective stimulator of muscle protein anabolism.
A fatty meal induces vasodilatation (of both resting and stimulated forearm flow) in healthy young adults, an effect most likely mediated by the vasodilator actions of insulin. We therefore hypothesized that an impaired meal-related vascular response might be an in vivo marker of vascular insulin resistance, related to the presence of diabetes and/or higher age. Postprandial vascular responses were assessed in three groups of subjects: 15 Type 2 diabetic subjects (age 58 +/- 8 yr), 15 age-, gender-, and body mass index (BMI)-matched older control subjects (age 57 +/- 9 yr), and 15 healthy young control subjects (age 33 +/- 7 yr). Studies were carried out before and 3 and 6 h after a standardized high-fat meal (1,030 kcal, 61 g fat). Forearm microvascular flows were measured by strain gauge plethysmography and large-artery function by ultrasound. Resting blood flow and hyperemic area under curve (AUC) flow were not significantly different in diabetic subjects (resting 117 +/- 42% and AUC 134 +/- 46% of premeal values) compared with age-matched controls (resting 131 +/- 39% and AUC 134 +/- 47%); however, the response in diabetic subjects was blunted compared with young controls (resting 171 +/- 67% and AUC 173 +/- 99% of premeal values; P = 0.02 and P = 0.18, respectively). On multiple regression analysis, we found that increasing age (but not BMI or diabetes) was significantly associated with impaired postprandial vascular responses (resting: r = -0.4, P = 0.002; AUC: r = -0.4, P = 0.006). Therefore, meal ingestion results in impaired vasodilator responses in older nondiabetic and diabetic adults, related to aging rather than insulin resistance.
The anabolic effect of resistance exercise is enhanced by the provision of dietary protein.
We aimed to determine the ingested protein dose response of muscle (MPS) and albumin protein synthesis (APS) after resistance exercise. In addition, we measured the phosphorylation of candidate signaling proteins thought to regulate acute changes in MPS.
Six healthy young men reported to the laboratory on 5 separate occasions to perform an intense bout of leg-based resistance exercise. After exercise, participants consumed, in a randomized order, drinks containing 0, 5, 10, 20, or 40 g whole egg protein. Protein synthesis and whole-body leucine oxidation were measured over 4 h after exercise by a primed constant infusion of [1-(13)C]leucine.
MPS displayed a dose response to dietary protein ingestion and was maximally stimulated at 20 g. The phosphorylation of ribosomal protein S6 kinase (Thr(389)), ribosomal protein S6 (Ser(240/244)), and the epsilon-subunit of eukaryotic initiation factor 2B (Ser(539)) were unaffected by protein ingestion. APS increased in a dose-dependent manner and also reached a plateau at 20 g ingested protein. Leucine oxidation was significantly increased after 20 and 40 g protein were ingested.
Ingestion of 20 g intact protein is sufficient to maximally stimulate MPS and APS after resistance exercise. Phosphorylation of candidate signaling proteins was not enhanced with any dose of protein ingested, which suggested that the stimulation of MPS after resistance exercise may be related to amino acid availability. Finally, dietary protein consumed after exercise in excess of the rate at which it can be incorporated into tissue protein stimulates irreversible oxidation.
We investigated how myofibrillar protein synthesis (MPS) and muscle anabolic signalling were affected by resistance exercise at 20-90% of 1 repetition maximum (1 RM) in two groups (25 each) of post-absorptive, healthy, young (24 +/- 6 years) and old (70 +/- 5 years) men with identical body mass indices (24 +/- 2 kg m(-2)). We hypothesized that, in response to exercise, anabolic signalling molecule phosphorylation and MPS would be modified in a dose-dependant fashion, but to a lesser extent in older men. Vastus lateralis muscle was sampled before, immediately after, and 1, 2 and 4 h post-exercise. MPS was measured by incorporation of [1,2-(13)C] leucine (gas chromatography-combustion-mass spectrometry using plasma [1,2-(13)C]alpha-ketoisocaparoate as surrogate precursor); the phosphorylation of p70 ribosomal S6 kinase (p70s6K) and eukaryotic initiation factor 4E binding protein 1 (4EBP1) was measured using Western analysis with anti-phosphoantibodies. In each group, there was a sigmoidal dose-response relationship between MPS at 1-2 h post-exercise and exercise intensity, which was blunted (P < 0.05) in the older men. At all intensities, MPS fell in both groups to near-basal values by 2-4 h post-exercise. The phosphorylation of p70s6K and 4EBP1 at 60-90% 1 RM was blunted in older men. At 1 h post-exercise at 60-90% 1 RM, p70s6K phosphorylation predicted the rate of MPS at 1-2 h post-exercise in the young but not in the old. The results suggest that in the post-absorptive state: (i) MPS is dose dependant on intensity rising to a plateau at 60-90% 1 RM; (ii) older men show anabolic resistance of signalling and MPS to resistance exercise.
Muscle mass accretion is accomplished by heavy-load resistance training. The effect of light-load resistance exercise has been far more sparsely investigated with regard to potential effect on muscle size and contractile strength. We applied a resistance exercise protocol in which the same individual trained one leg at 70% of one-repetition maximum (1RM) (heavy load, HL) while training the other leg at 15.5% 1RM (light load, LL). Eleven sedentary men (age 25 +/- 1 yr) trained for 12 wk at three times/week. Before and after the intervention muscle hypertrophy was determined by magnetic resonance imaging, muscle biopsies were obtained bilaterally from vastus lateralis for determination of myosin heavy chain (MHC) composition, and maximal muscle strength was assessed by 1RM testing and in an isokinetic dynamometer at 60 degrees /s. Quadriceps muscle cross-sectional area increased (P < 0.05) 8 +/- 1% and 3 +/- 1% in HL and LL legs, respectively, with a greater gain in HL than LL (P < 0.05). Likewise, 1RM strength increased (P < 0.001) in both legs (HL: 36 +/- 5%, LL: 19 +/- 2%), albeit more so with HL (P < 0.01). Isokinetic 60 degrees /s muscle strength improved by 13 +/- 5% (P < 0.05) in HL but remained unchanged in LL (4 +/- 5%, not significant). Finally, MHC IIX protein expression was decreased with HL but not LL, despite identical total workload in HL and LL. Our main finding was that LL resistance training was sufficient to induce a small but significant muscle hypertrophy in healthy young men. However, LL resistance training was inferior to HL training in evoking adaptive changes in muscle size and contractile strength and was insufficient to induce changes in MHC composition.
