Objective Nutritional intervention studies have indicated that whey protein- and leucine-enriched multi-nutrient formulas high in vitamin D3 are optimal medical nutrition recipes for treating sarcopenia. The present study undertakes a scoping review of research on whey protein- and leucine-enriched multi-nutrient formulas high in vitamin D3 in older adults with sarcopenia to highlight the impact of feeding and feeding with exercise on body composition, strength, and physical function. Design Online databases identified studies published from 2005-2023, for which we selected 11 English-language studies that experimented with a whey protein—and leucine-enriched multi-nutrient formula(e) high in vitamin D3 on measures of sarcopenia as the primary outcome variables in older adults diagnosed as sarcopenic. Results Nine registered human clinical trials and two unregistered human clinical trials were included in the analysis. All studies included sarcopenic older adults ages 66.5 y to 86.5 y. Two intervention types were identified: nutrition only or nutrition + exercise rehabilitation. The nutritional interventions improved lean mass, strength, and physical function. Conclusion There is evidence for the effectiveness of several types of whey protein- and leucine-enriched multi-nutrient formulas high in vitamin D3 in improving lean mass and physical performance in older adults recovering from sarcopenia. This is the first scoping review to show that specific formula(e) used with rehabilitation programs can alleviate sarcopenic obesity, support skeletal bone, and improve body composition, lean mass, and physical function with or without exercise (CRD42022342953).

Leucine is a critical amino acid stimulating myofibrillar protein synthesis (MyoPS). The consumption of higher leucine-containing drinks stimulates MyoPS, but we know less about higher leucine solid foods. Here, we examined the effect of short-term resistance exercise training (STRT) combined with supplementation of a protein and leucine-enriched bar, com-pared with STRT alone, on integrated (%/day) rates of MyoPS and anabolic protein signaling. In a nonblinded, randomized crossover trial, eight young adults performed four sessions of STRT without or while consuming the study bar (STRT+Leu, 16 g of protein containing similar to 3 g of leucine) for two 4-day phases, separated by 2 days nonexercise (Rest) washout. In combination with serial muscle biopsies, deuterated water permitted the measurement of MyoPS and protein signaling phosphorylation. MyoPS during STRT (1.43 +/- 0.06%/day) and STRT+Leu (1.53 +/- 0.06%/day) were greater than Rest (1.31 +/- 0.05%/day), and MyoPS during STRT+Leu (1.53 +/- 0.06%/day) was greater than STRT alone (1.43 +/- 0.06%/day). STRT+Leu increased the ratio of phospho-rylated to total mechanistic target of rapamycin and 4EBP1 compared to Rest. Engaging in STRT increased integrated MyoPS and protein signaling in young adults and was enhanced with increased protein intake derived from a leucine-enriched protein bar. This study was registered at clinicaltrials.gov as NCT03796897.

BACKGROUND:Limited data are available examining dietary interventions for optimizing protein and leucine intake to stimulate muscle protein synthesis (MPS) in older humans. OBJECTIVES:We aimed to investigate the aminoacidemia and appetite responses of older adults after consuming breakfast, a meal frequently consumed with high-carbohydrate and below-par amounts of protein and leucine for stimulating MPS. METHODS:Five men and 3 women (means ± SD; age: 74 ± 7 y, BMI: 25.7 ± 4.9 kg/m2, fat- and bone-free mass: 63 ± 7 kg) took part in this experiment in which they consumed breakfasts with low-protein (LP = 13 ± 2 g), high-protein (HP = 32 ± 5 g), and LP followed by a protein- and leucine-enriched bar formulation 2 h later (LP + Bar = 29 ± 2 g). The LP, HP, and LP + Bar breakfast conditions contained 519 ± 86 kcal, 535 ± 83 kcal, and 739 ± 86 kcal, respectively. Blood samples were drawn for 6 h and analyzed for amino acid, insulin, and glucose concentrations. Visual analog scales were assessed for hunger, fullness, and desire to eat. RESULTS:The net AUC for essential amino acid (EAA) exposure was similar between the LP + Bar and HP conditions but greater in the HP condition compared with the LP condition. Peak leucinemia was higher in the LP + Bar condition compared with the HP, and both were greater than the LP condition. Net leucine exposure was similar between HP and LP + Bar, and both were greater than LP. Hunger was similarly reduced in LP + Bar and HP, and LP + Bar resulted in a greater hunger reduction than LP. Both LP + Bar and HP resulted in greater net fullness scores than LP. CONCLUSIONS:Consuming our bar formulation increased blood leucine availability and net exposure to EAAs to a similar degree as consuming a high-protein meal. High-protein at breakfast results in a greater net exposure to EAAs and leucine, which could support MPS in older persons. This study was registered at clinicaltrials.gov as NCT03712761.

We investigated the effects of ingesting a leucine-enriched essential amino acid (EAA) gel alone or combined with resistance exercise (RE) versus RE alone (control) on plasma aminoacidemia and intramyocellular anabolic signaling in healthy younger (28 ± 4 years) and older (71 ± 3 years) adults. Blood samples were obtained throughout the three trials, while muscle biopsies were collected in the postabsorptive state and 2 h following RE, following the consumption of two 50 mL EAA gels (40% leucine, 15 g total EAA), and following RE with EAA (combination (COM)). Protein content and the phosphorylation status of key anabolic signaling proteins were determined via immunoblotting. Irrespective of age, during EAA and COM peak leucinemia (younger: 454 ± 32 µM and 537 ± 111 µM; older: 417 ± 99 µM and 553 ± 136 µM) occurred ~60–120 min post-ingestion (younger: 66 ± 6 min and 120 ± 60 min; older: 90 ± 13 min and 78 ± 12 min). In the pooled sample, the area under the curve for plasma leucine and the sum of branched-chain amino acids was significantly greater in EAA and COM compared with RE. For intramyocellular signaling, significant main effects were found for condition (mTOR (Ser2481), rpS6 (Ser235/236)) and age (S6K1 (Thr421/Ser424), 4E-BP1 (Thr37/46)) in age group analyses. The phosphorylation of rpS6 was of similar magnitude (~8-fold) in pooled and age group data 2 h following COM. Our findings suggest that a gel-based, leucine-enriched EAA supplement is associated with aminoacidemia and a muscle anabolic signaling response, thus representing an effective means of stimulating muscle protein anabolism in younger and older adults following EAA and COM.

The Dietary Reference Intakes set the protein RDA for persons >19 y of age at 0.8 g protein ⋅ kg body weight-1 ⋅ d-1. A growing body of evidence suggests, however, that the protein RDA may be inadequate for older individuals. The evidence for recommending a protein intake greater than the RDA comes from a variety of metabolic approaches. Methodologies centered on skeletal muscle are of paramount importance given the age-related decline in skeletal muscle mass and function (sarcopenia) and the degree to which dietary protein could mitigate these declines. In addition to evidence from short-term experimental trials, observational data show that higher protein intakes are associated with greater muscle mass and, more importantly, better muscle function with aging. We are in dire need of more evidence from longer-term intervention trials showing the efficacy of protein intakes that are higher than the RDA in older persons to support skeletal muscle health. We propose that it should be recommended that older individuals consume ≥1.2 g protein · kg-1 · d-1 and that there should be an emphasis on the intake of the amino acid leucine, which plays a central role in stimulating skeletal muscle anabolism. Critically, the often-cited potential negative effects of consuming higher protein intakes on renal and bone health are without a scientific foundation in humans.

Purpose of review Skeletal muscle mass with aging, during critical care, and following critical care is a determinant of quality of life and survival. In this review, we discuss the mechanisms that underpin skeletal muscle atrophy and recommendations to offset skeletal muscle atrophy with aging and during, as well as following, critical care. Recent findings Anabolic resistance is responsible, in part, for skeletal muscle atrophy with aging, muscle disuse, and during disease states. Anabolic resistance describes the reduced stimulation of muscle protein synthesis to a given dose of protein/amino acids and contributes to declines in skeletal muscle mass. Physical inactivity induces: anabolic resistance (that is likely exacerbated with aging), insulin resistance, systemic inflammation, decreased satellite cell content, and decreased capillary density. Critical illness results in rapid skeletal muscle atrophy that is a result of both anabolic resistance and enhanced skeletal muscle breakdown. Summary Insofar as atrophic loss of skeletal muscle mass is concerned, anabolic resistance is a principal determinant of age-induced losses and appears to be a contributor to critical illness-induced skeletal muscle atrophy. Older individuals should perform exercise using both heavy and light loads three times per week, ingest at least 1.2 g of protein/kg/day, evenly distribute their meals into protein boluses of 0.40 g/kg, and consume protein within 2 h of retiring for sleep. During critical care, early, frequent, and multimodal physical therapies in combination with early, enteral, hypocaloric energy (∼10–15 kcal/kg/day), and high-protein (>1.2 g/kg/day) provision is recommended.

We examined the aminoacidemic, glycemic, and insulinemic responses following ingestion of 25 g of native whey protein, micellar casein, and a 1:1 blend of whey and casein in randomized order in young adult men. Blood samples were drawn at baseline and at regular intervals for 6 h following ingestion. Area under curve and peak plasma essential amino acid concentrations after the ingestion of the protein blend were similar to whey and greater compared with casein.

The Dietary Reference Intakes set the protein RDA for persons >19 y of age at 0.8 g protein.kg body weight(-1).d(-1). A growing body of evidence suggests, however, that the protein RDA may be inadequate for older individuals. The evidence for recommending a protein intake greater than the RDA comes from a variety of metabolic approaches. Methodologies centered on skeletal muscle are of paramount importance given the age-related decline in skeletal muscle mass and function (sarcopenia) and the degree to which dietary protein could mitigate these declines. In addition to evidence from short-term experimental trials, observational data show that higher protein intakes are associated with greater muscle mass and, more importantly, better muscle function with aging. We are in dire need of more evidence from longer-term intervention trials showing the efficacy of protein intakes that are higher than the RDA in older persons to support skeletal muscle health. We propose that it should be recommended that older individuals consume >= 1.2 g protein.kg(-1).d(-1) and that there should be an emphasis on the intake of the amino acid leucine, which plays a central role in stimulating skeletal muscle anabolism. Critically, the often-cited potential negative effects of consuming higher protein intakes on renal and bone health are without a scientific foundation in humans.

The purposes of this study were to: (a) examine the age-related patterns of differences in height (HT), body mass (BM), percent body fat (% fat), body mass index (BMI), and skinfolds (SF) in 11- to 18-year-old wrestlers; (b) determine the coherence of direct (% fat) and indirect (BMI and SFs) indicators of adiposity in the wrestlers; and (c) compare the age-related patterns and mean values for HT, BM, BMI, subscapular, and triceps SF for the wrestlers to those of national samples of boys from the National Health and Nutrition Examination Survey (NHANES) database. One hundred thirty wrestlers were divided into 8 independent yearly age groups (AG): AG11-AG18 years. Height, BM, BMI, subscapular SF, triceps SF, medial calf SF, thigh SF, sum of SFs, and % fat were assessed. There were no differences between the wrestlers and NHANES samples for age-related patterns of BMI (0.61 and 0.63 kg·m·y), subscapular SF (0.47 and 0.37 mm·y), or triceps SF (-0.31 and -0.39 mm·y). Furthermore, the wrestlers displayed no differences in % fat between age groups. The results indicated that: (a) dissociations existed between the direct and indirect indicators of adiposity; (b) the wrestlers were similar in height but had smaller upper-body SFs when compared with NHANES samples; and (c) participation in wrestling (1-8 years) had no adverse effects on the normal age-related growth patterns for HT, but favorable effects on measures of adiposity.

OBJECTIVE: This study examined the effects of gender on peak torque (PT), average power (AP), and the time (AMP) and frequency (MPF) domain parameters of the electromyographic (EMG) and mechanomyographic (MMG) signals following very short-term resistance training (VST) of the forearm flexors. Based on the results of previous studies it was hypothesized that three training sessions would increase PT, EMG MPF, and MMG MPF of the forearm flexors at 60 and 180 degrees/s in men only, without changes to AP, EMG AMP, or MMG AMP for either men or women.METHODS: Nine men and nine women completed two pretests, three training sessions, and a posttest that included concentric isokinetic muscle actions of the forearm flexors at 60 and 180 degrees/s. The AMP and MPF of the EMG and MMG signals were recorded from the biceps brachii.RESULTS: The results indicate increases in PT, AP, and MMG AMP at 60 and 180 degrees/s for the men only, but no changes in EMG AMP, EMG MPF, or MMG MPF for either the men or women.CONCLUSION: There were gender differences in the PT and AP responses to VST of the forearm flexors that were not associated with increased agonist muscle activation. These findings have implications for the development of gender-specific VST programs for the forearm flexors in clinical settings.

Bergstrom, HC, Housh, TJ, Zuniga, JM, Traylor, DA, Lewis, RW Jr, Camic, CL, Schmidt, RJ, and Johnson, GO. Differences among estimates of critical power and anaerobic work capacity derived from five mathematical models and the three-minute all-out test. J Strength Cond Res 28(3): 592-600, 2014-Estimates of critical power (CP) and anaerobic work capacity (AWC) from the power output vs. time relationship have been derived from various mathematical models. The purpose of this study was to examine estimates of CP and AWC from the multiple work bout, 2- and 3-parameter models, and those from the 3-minute all-out CP (CP3min) test. Nine college-aged subjects performed a maximal incremental test to determine the peak oxygen consumption rate and the gas exchange threshold. On separate days, each subject completed 4 randomly ordered constant power output rides to exhaustion to estimate CP and AWC from 5 regression models (2 linear, 2 nonlinear, and 1 exponential). During the final visit, CP and AWC were estimated from the CP3min test. The nonlinear 3-parameter (Nonlinear-3) model produced the lowest estimate of CP. The exponential (EXP) model and the CP3min test were not statistically different and produced the highest estimates of CP. Critical power estimated from the Nonlinear-3 model was 14% less than those from the EXP model and the CP3min test and 4-6% less than those from the linear models. Furthermore, the Nonlinear-3 and nonlinear 2-parameter (Nonlinear-2) models produced significantly greater estimates of AWC than did the linear models and CP3min. The current findings suggested that the Nonlinear-3 model may provide estimates of CP and AWC that more accurately reflect the asymptote of the power output vs. time relationship, the demarcation of the heavy and severe exercise intensity domains, and anaerobic capabilities than will the linear models and CP3min test.

The purpose of this study was to examine the effects of anatabine supplementation in conjunction with unilateral, maximal eccentric isokinetic muscle actions on serum markers of muscle damage and pro-inflammatory cytokines in humans. Seventeen men (mean±S.D. age=22.4±3.2 yrs) participated in this double-blinded, placebo-controlled, crossover study. Participants were randomly assigned to two 10-day conditions (anatabine and placebo) separated by a 2–4 week washout period. After seven days of supplementation, blood was sampled immediately prior to PRE, immediately following POST, and 24, 48, and 72h after 6 sets of 10 repetitions of unilateral, maximal eccentric isokinetic forearm flexion exercise. Concentrations of serum creatine kinase, lactate dehydrogenase, myoglobin, high sensitivity c-reactive protein, and TNF-α were measured. Creatine kinase, myoglobin, and lactate dehydrogenase increased (P<0.05), while high sensitivity c-reactive protein and TNF-α did not change (P>0.05) after the eccentric exercise during both conditions. Lactate dehydrogenase was higher (P<0.05) during the anatabine condition. The primary findings of this study were two-fold: (a) anatabine had no beneficial effects on traditional markers of muscle damage (creatine kinase, lactate dehydrogenase, and myoglobin) compared to placebo after the eccentric exercise protocol, and (b) the eccentric exercise protocol did not elicit increase in the pro-inflammatory cytokines (c-reactive protein and TNF-α). Future studies are needed to examine the effects of anatabine on naturally-occurring inflammation that is common with aging or obesity. Furthermore, additional research is needed to examine the relationship between muscle damage and inflammation after eccentric exercises of different modes, durations, and intensities.

This study examined the time courses of recovery for isometric peak torque and rate of torque development (RTD) after eccentric-induced muscle damage. 18 men completed 6 sets of 10 maximal eccentric isokinetic muscle actions at 30 degrees s(-1). Peak torque, peak RTD and RTD at 10 (RTD10), 50 (RTD50), 100 (RTD100) and 200ms (RTD200), serum creatine kinase and lactate dehydrogenase were measured before (PRE), immediately after (POST), 24, 48 and 72h after eccentric exercise. Creatine kinase and lactate dehydrogenase increased from 139 to 6457 and from 116 to 199IUL(-1) from PRE to 72h, respectively. Peak torque and all RTDs decreased at POST. Peak torque and RTD200 remained lower than PRE through 72h. Peak RTD remained lower than PRE through 48h, but was not different from PRE at 72h. RTD10 and RTD100 were lower than PRE through 24h, but were not different from PRE at 48 and 72h. RTD50 decreased at POST, but was not different from PRE at 24h. Early phase RTDs recovered more quickly than PT and RTD200. Early phase RTDs may reflect neural mechanisms underlying eccentric-induced force decrements, while late RTDs may describe the same physiological mechanisms as PT.

The purpose of the current study was to examine the patterns of responses for torque, mechanomyographic (MMG) amplitude, MMG frequency, electromyographic (EMG) amplitude, and EMG frequency across 30 repeated maximal eccentric muscle actions of the leg extensors. Eleven moderately trained females performed an eccentric fatigue protocol at 30°/s with MMG and EMG signals recorded from the vastus lateralis. The results indicated there were significant (P<.05) decreases in MMG frequency (linear, r2=.395), EMG frequency (linear, r2=.177), and torque (linear, r2=.570; % decline=9.8±13.3%); increases in MMG amplitude (linear, r2=.783); and no change in EMG amplitude (r2=.003). These findings suggested that the neural strategies used to modulate torque during fatiguing eccentric muscle actions involved de-recruitment of motor units, reduced firing rates, and synchronization. In addition, the decreases in eccentric torque were more closely associated with changes in MMG frequency than EMG frequency. Thus, these findings indicated that MMG frequency, compared with EMG frequency, more accurately tracks fatigue during repeated maximal eccentric muscle actions.

Twenty-one men (mean +/- SD; age = 23.5 +/- 2.6 years, BMI = 26.0 +/- 2.4 kg.m(-2)) completed this randomized, double-blinded, placebo-controlled, crossover study to examine acute responses to a thermogenic nutritional supplement. Each testing session included: (a) 30 minutes resting, followed by placebo or thermogenic nutritional supplementation, (b) 50 minutes postsupplementation resting, (c) 60 minutes walking, and (d) 50 minutes postexercise recovery. Gas exchange variables and heart rate (HR) were recorded during each phase. Blood pressure was recorded during all phases except exercise. Ratings of perceived exertion (RPE) were recorded only during exercise. There were no significant differences for any of the measures between the supplement and placebo during the initial resting or postsupplementation phases. During exercise, energy expenditure (EE) (placebo = 18.98-19.06 kJ.min(-1) and supplement = 19.44-19.82 kJ.min(-1)) and (V) over dotO(2) (placebo = 11.27-11.35 ml.kg(-1).min(-1); supplement = 11.64-11.82 ml.kg(-1).min(-1)) were greater for the supplement than placebo. There were no differences in respiratory exchange ratio (RER), HR, or RPE between the supplement and placebo during exercise. Postexercise, only (V) over dotO(2) (placebo = 3.53-3.63 ml.kg(-1).min(-1); supplement = 3.71-3.84 ml.kg(-1).min(-1)) was greater for the supplement than placebo, but there were no differences in EE, RER, HR, or blood pressure. These findings suggested that the specific blend of ingredients in the thermogenic nutritional supplement, when combined with exercise, increased the metabolic rate with minimal changes in cardiovascular function and no effect on RPE.

OBJECTIVE: This cross-sectional study examined the relationships between age and absolute peak torque (PT) as well as PT covaried for body weight (BW), height (HT), and/or fat-free weight (FFW) in young girl swimmers.METHODS: Twenty-nine girl swimmers (age = 12.4 +/- 1.9 yr) were measured for isokinetic elbow flexion and extension PT at 30, 180, 300 degrees . s(-1), as well as BW, HT, and FFW. Zero-order correlations as well as first, second, and third-order partial correlations were used to determine the relationships for age versus PT and age versus PT covaried for BW, HT, and/or FFW.RESULTS: There were age-related increases for all absolute PT measures (r = 0.47 to 0.77), except elbow flexion at 300 degrees . s(-1). For all but one of the measures (forearm extension at 30 degrees . s(-1); r = 0.42 to 0.56), the increases in PT were accounted for by changes in BW, HT, and/or FFW.CONCLUSION: The results of this study indicated that agef-related increases in PT for four of the six measures were accounted for by BW, HT, and/or FFW. The age-related increases in PT for elbow flexion at 30 degrees . s(-1) independent of BW, HT, and/or FFW, may have been due to neuromuscular maturation.

OBJECTIVE: The purpose of the present study was to examine the effects of three sessions of concentric isokinetic training of the forearm flexors on peak torque (PT) at maximal voluntary isometric contraction (MVIC), 60, 180, and 300 degrees . s(-1) in males.METHODS: Ten adult males (mean age +/- SD = 21.8 +/- 1.2 years; body mass = 87.8 +/- 18.4 kg; height = 182 +/- 9.5 cm) completed two pretests (pretest 1 and pretest 2) and a posttest that included maximal unilateral isometric and concentric isokinetic forearm flexion (non-dominant arm) muscle actions at MVIC, 60, 180, and 300 degrees . s(-1). During the three days of training, the subjects performed five sets of ten maximal isokinetic concentric forearm flexion (non-dominant arm) repetitions at 60 degrees . s(-1).RESULTS: A three (pretest 1, pretest 2, and posttest) x four (MVIC, 60, 180, 300 degrees . s(-1)) repeated measures ANOVA indicated that there was no significant (p > 0.05) interaction, but significant main effects for time and velocity. The follow-up t-tests for marginal means indicated that the posttest (63.0 +/- 13.1 Nm) was significantly greater than pretest 1 (55.8 +/- 15.1 Nm) and pretest 2 (55.2 +/- 12.4 Nm).CONCLUSION: Thus, the very short-term resistance training (VST) resulted in the same pattern of increase in PT at each velocity. In addition, PT decreased significantly with velocity. The current findings indicated that three days of concentric isokinetic training for the forearm flexors were sufficient to elicit increases in PT across a velocity spectrum (MVIC to 300 degrees . s(-1)).