Measured and predicted resting metabolic rate of Dutch and Norwegian Paralympic athletes.

BACKGROUND: While the resting metabolic rate (RMR) is crucial for understanding athletes' energy requirements, limited information is available on the RMR of Paralympic athletes. OBJECTIVE: To determine RMR and its predictors in a diverse cohort of Paralympic athletes and evaluate the agreement between measured and predicted RMR from both newly developed and preexisting equations. DESIGN: This cross-sectional study, conducted between September 2020 and September 2022 in the Netherlands and Norway, assessed RMR in Paralympic athletes by ventilated hood indirect calorimetry and body composition by dual energy X-ray absorptiometry. PARTICIPANTS: Sixty-seven Paralympic athletes (male: n=37; female: n=30) competing in various sports, with a spinal cord disorder (SCD; n=22), neurological condition (n=8), limb deficiency (n=18), visual or hearing impairment (n=7) or other disability (n=12) participated. MAIN OUTCOME MEASURES: RMR, fat-free mass (FFM), body mass, and triiodothyronine (T3) concentrations were assessed. STATISTICAL ANALYSES: Multiple regression analyses were conducted with height, FFM, body mass, sex, T3 concentration, and disabilities as potential predictors of RMR. Differences between measured and predicted RMRs were analyzed for individual accuracy, root mean square error (RMSE), and intraclass correlation (ICC). RESULTS: Mean RMR was 1386±258 kcal/day for females and 1686±302 kcal/day for males. Regression analysis identified FFM, T3 concentrations and the presence of a spinal cord disorder (SCD), as the main predictors of RMR (adjusted R2=0.71; F=50.3; P<0.001). The novel prediction equations based on these data, as well as pre-existing equations of Chun et al. and Nightingale and Gorgey performed well on accuracy (>60% of participants within 10% of measured RMR), had a good reliability (ICC >0.78), and low RMSE (≤141 kcal). CONCLUSION: FFM, total T3 concentrations, and the presence of SCD are the main predictors of RMR in Paralympic athletes. Both the current study's prediction equations and those by Chun et al. and Nightingale and Gorgey align well with measured RMR, offering accurate prediction equations for the RMR of Paralympic athletes.

Do Paralympic athletes suffer from brittle bones? Prevalence and risk factors of low bone mineral density in Paralympic athletes.

Background: Bone health may be a concern in Paralympic athletes, given the presence of multiple risk factors predisposing these athletes to low bone mineral density (BMD). Objective: We aimed to assess the prevalence of low BMD among Paralympic athletes participating in various sport disciplines, and to identify potential risk factors for low BMD. Methods: Seventy Paralympic athletes, of whom 51 % were wheelchair-dependent, were included in this cross-sectional study. BMD of the whole-body, lumbar spine, total hip, and femoral neck were assessed by dual-energy x-ray absorptiometry. Comparisons between groups were conducted by one-way ANOVA, and regression analyses were conducted to identify potential risk factors for low BMD. Results: The prevalence of low BMD (Z-score < -1.0) was highest at femoral neck (34 %), followed by total hip (31 %), whole-body (21 %), and lumbar spine (18 %). Wheelchair-dependent athletes had significantly lower BMD Z-scores compared to the non-wheelchair-dependent athletes at whole-body level (-0.5 ± 1.4 vs 0.2 ± 1.3; P = 0.04), total hip (-1.1 ± 1.2 vs 0.0 ± 1.1; P < 0.01), and femoral neck (-1.0 ± 1.3 vs -0.1 ± 1.2; P < 0.01). At the lumbar spine, low BMD was completely absent in wheelchair basketball and tennis players. Regression analyses identified body mass, wheelchair dependence, and type of sport, as the main risk factors for low BMD. Conclusions: In this cohort of Paralympic athletes, low BMD is mainly present at the hip, and to a lesser extent at the whole-body and lumbar spine. The most prominent risk factors for low BMD in Paralympic athletes are related to mechanical loading patterns, including wheelchair use, the type of sport, and body mass.

"It gave me a sense of achievement and a sense of purpose"-a qualitative study of patient experiences of a virtually supervised exercise program for adults with advanced cancer and cachexia.

People with advanced cancer and cachexia experience significant body weight loss, adversely impacting physical function and quality of life (QOL). Effective, evidence-based treatments for cancer cachexia are lacking, leaving patients with unmet needs. Exercise holds promise to improve patient QOL. However, information on patients' experiences of exercise, including their ability to cope with structured exercise, is limited. PURPOSE: To explore patient experiences completing a structured, supervised exercise program for people with cachexia due to advanced cancer. METHODS: Semi-structured interviews were conducted with participants enrolled in a phase II feasibility, randomized controlled trial to explore their experiences of an 8-week virtually supervised exercise program delivered via videoconference technology. Interviews were analysed using reflexive thematic analysis. RESULTS: Seventeen participants completed interviews (female n = 9, 53%). Main interview themes included the following: (1) Deciding to exercise involves balancing concerns and expectations, (2) the exercise program is a positive experience, and (3) moving forward after the exercise program. While some participants initially held doubts about their physical capabilities and exercise safety, most wanted to exercise to enhance their wellbeing. Participants described the exercise program as a positive experience, offering diverse benefits. Some would have preferred in-person exercise, but all agreed the virtual format increased convenience. Participants emphasized the need to recommend the program to others in similar circumstances. They underscored the necessity and desire for ongoing support to sustain their new exercise habits. CONCLUSION: Based on patient experiences, virtually supervised exercise programming appears to be feasible and meaningful to people with advanced cancer and cachexia.

Comparison of intramyocellular lipid metabolism in patients with diabetes and male athletes.

Despite opposing insulin sensitivity and cardiometabolic risk, both athletes and patients with type 2 diabetes have increased skeletal myocyte fat storage: the so-called "athlete's paradox". In a parallel non-randomised, non-blinded trial (NCT03065140), we characterised and compared the skeletal myocyte lipid signature of 29 male endurance athletes and 30 patients with diabetes after undergoing deconditioning or endurance training respectively. The primary outcomes were to assess intramyocellular lipid storage of the vastus lateralis in both cohorts and the secondary outcomes were to examine saturated and unsaturated intramyocellular lipid pool turnover. We show that athletes have higher intramyocellular fat saturation with very high palmitate kinetics, which is attenuated by deconditioning. In contrast, type 2 diabetes patients have higher unsaturated intramyocellular fat and blunted palmitate and linoleate kinetics but after endurance training, all were realigned with those of deconditioned athletes. Improved basal insulin sensitivity was further associated with better serum cholesterol/triglycerides, glycaemic control, physical performance, enhanced post insulin receptor pathway signalling and metabolic sensing. We conclude that insulin-resistant, maladapted intramyocellular lipid storage and turnover in patients with type 2 diabetes show reversibility after endurance training through increased contributions of the saturated intramyocellular fatty acid pools. Clinical Trial Registration: NCT03065140: Muscle Fat Compartments and Turnover as Determinant of Insulin Sensitivity (MISTY).

Quantification and interpretation of postprandial whole-body protein metabolism using stable isotope methodology: a narrative review.

Stable isotopes are routinely applied to determine the impact of factors such as aging, disease, exercise, and feeding on whole-body protein metabolism. The most common approaches to quantify whole-body protein synthesis, breakdown, and oxidation rates and net protein balance are based on the quantification of plasma amino acid kinetics. In the postabsorptive state, plasma amino acid kinetics can easily be assessed using a constant infusion of one or more stable isotope labeled amino acid tracers. In the postprandial state, there is an exogenous, dietary protein-derived amino acid flux that needs to be accounted for. To accurately quantify both endogenous as well as exogenous (protein-derived) amino acid release in the circulation, the continuous tracer infusion method should be accompanied by the ingestion of intrinsically labeled protein. However, the production of labeled protein is too expensive and labor intensive for use in more routine research studies. Alternative approaches have either assumed that 100% of exogenous amino acids are released in the circulation or applied an estimated percentage based on protein digestibility. However, such estimations can introduce large artifacts in the assessment of whole-body protein metabolism. The preferred estimation approach is based on the extrapolation of intrinsically labeled protein-derived plasma bioavailability data obtained in a similar experimental design setting. Here, we provide reference data on exogenous plasma amino acid release that can be applied to allow a more accurate routine assessment of postprandial protein metabolism. More work in this area is needed to provide a more extensive reference data set.

Access to a pre-sleep protein snack increases daily energy and protein intake in surgical hospitalized patients.

BACKGROUND & AIM: In hospitalized patients, daily protein intake remains far below WHO requirements for healthy adults (0.8 g·kg-1·d-1) as well as ESPEN guidelines for patients (1.2-1.5 g·kg-1·d-1). Providing access to a pre-sleep protein dense snack between dinner and going to bed may serve as a great opportunity to increase daily energy and protein intake in hospitalized patients. However, it remains to be assessed whether protein provision prior to sleep effectively increases protein intake, or may reduce food intake throughout the remainder of the day(s). The present study evaluated the impact of giving access to a pre-sleep snack on daily energy and protein intake in patients throughout their hospitalization. METHODS: Patients admitted to the surgical wards of the Maastricht University Medical Centre+ were randomly allocated to usual care (n = 51) or given access to a pre-sleep snack (n = 50). The pre-sleep snack consisted of 103 g cheese cubes (30 g protein) provided between 7:30 and 9:30 PM, prior to sleep. All food provided and all food consumed was weighed and recorded throughout (2-7 days) hospitalization. Daily energy and protein intake and distribution were calculated. Data were analyzed by independent T-Tests with P < 0.05 considered as statistically significant. RESULTS: Daily energy intake was higher in the pre-sleep group (1353 ± 424 kcal d-1) when compared to the usual care group (1190 ± 402 kcal·d-1; P = 0.049). Providing patients access to a pre-sleep snack resulted in a 17% (11 ± 9 g) higher daily protein intake (0.81 ± 0.29 g·kg-1·d-1) when compared to the usual care group (0.69 ± 0.28 g·kg-1·d-1; P = 0.045). Protein intake at breakfast, lunch, and dinner did not differ between the pre-sleep and usual care groups (all P > 0.05). CONCLUSION: Providing access to a pre-sleep protein snack, in the form of protein dense food items such as cheese, represents an effective dietary strategy to increase daily energy and protein intake in hospitalized patients. Patients consuming pre-sleep protein snacks do not compensate by lowering energy or protein intake throughout the remainder of the days. Pre-sleep protein dense food provision should be implemented in hospital food logistics to improve the nutritional intake of patients. TRIAL REGISTER NO: NL8507 (https://trialsearch.who.int/).

Coingestion of Collagen With Whey Protein Prevents Postexercise Decline in Plasma Glycine Availability in Recreationally Active Men.

Whey protein ingestion during recovery from exercise increases myofibrillar but not muscle connective protein synthesis rates. It has been speculated that whey protein does not provide sufficient glycine to maximize postexercise muscle connective protein synthesis rates. In the present study, we assessed the impact of coingesting different amounts of collagen with whey protein as a nutritional strategy to increase plasma glycine availability during recovery from exercise. In a randomized, double-blind, crossover design, 14 recreationally active men (age: 26 ± 5 years; body mass index: 23.8 ± 2.1 kg·m-2) ingested in total 30 g protein, provided as whey protein with 0 g (WHEY), 5 g (WC05); 10 g (WC10), and 15 g (WC15) of collagen protein immediately after a single bout of resistance exercise. Blood samples were collected frequently over 6 hr of postexercise recovery to assess postprandial plasma amino acid kinetics and availability. Protein ingestion strongly increased plasma amino acid concentrations (p < .001) with no differences in plasma total amino acid availability between treatments (p > .05). The postprandial rise in plasma leucine and essential amino acid availability was greater in WHEY compared with the WC10 and WC15 treatments (p < .05). Plasma glycine and nonessential amino acid concentrations declined following whey protein ingestion but increased following collagen coingestion (p < .05). Postprandial plasma glycine availability averaged -8.9 ± 5.8, 9.2 ± 3.7, 23.1 ± 6.5, and 39.8 ± 11.0 mmol·360 min/L in WHEY, WC05, WC10, and WC15, respectively (incremental area under curve values, p < .05). Coingestion of a small amount of collagen (5 g) with whey protein (25 g) is sufficient to prevent the decline in plasma glycine availability during recovery from lower body resistance-type exercise in recreationally active men.

Energy expenditure and dietary intake in professional female football players in the Dutch Women's League: Implications for nutritional counselling.

In contrast to male football players, research on the nutritional requirements of female football players is limited. This study aimed to assess total daily energy expenditure (TDEE) in professional female football players, along with body composition, physical activity and dietary intake. This observational study included 15 professional football players playing in the highest Dutch Women's League. TDEE was assessed by doubly labelled water over 14 days, along with resting metabolic rate (RMR; ventilated hood), fat-free mass (FFM; dual-energy x-ray absorptiometry), and dietary intake (24-h recalls). Physical activity energy expenditure (PAEE) was derived from subtracting RMR and estimated diet-induced thermogenesis (10%) from TDEE. TDEE was 2882 ± 278 kcal/day (58 ± 5 kcal/kg FFM) and significantly (p < 0.05) correlated with FFM (r = 0.62). PAEE was 1207 ± 213 kcal/d. Weighted energy intake was 2344 kcal [2023-2589]. Carbohydrate intakes were 3.2 ± 0.7, 4.4 ± 1.1 and 5.3 ± 1.9 g/kg body mass for rest, training and match days, respectively, while weighted mean protein intake was 1.9 ± 0.4 g/kg body mass. In conclusion, the energy requirements of professional female football players are moderate to high and can be explained by the substantial PAEE. To fuel these requirements, sports nutritionists should consider shifting the players' focus towards prioritizing adequate carbohydrate intakes, rather than emphasizing high protein consumption.

Becoming a World Champion Powerlifter at 71 Years of Age: It Is Never Too Late to Start Exercising.

This case study assessed body composition, muscle strength, cardiorespiratory fitness, and metabolic health of the present female world champion powerlifter in the 70+ age category who started resistance exercise training at 63 years of age with no prior experience with structured exercise training. Measures of body composition (magnetic resonance imaging, computed tomography, and dual-energy X-ray absorptiometry scanning, leg volume); strength (one-repetition maximum leg press and extension, maximum voluntary contraction, and handgrip strength); physical function (short physical performance battery); cardiorespiratory fitness (peak oxygen consumption); and metabolic health (oral glucose tolerance test) were assessed. In addition, a muscle biopsy was collected to assess muscle fiber type distribution and cross-sectional area (CSA). Where possible, data were compared with previously (un)published sex- and age-matched data using z scores. Skeletal muscle mass index was calculated by dividing limb muscle mass by height squared. Data from the control groups are expressed as mean ± 95% confidence interval. Our participant (age: 71 years; body mass: 64.5 kg; body mass index: 27.6 kg/m2) reported a good bone mineral density of 1.09 g/cm2 (T score between -1 and +1) and very low values of abdominal and organ body fat (i.e., between 20% and 70% lower compared with a reference group of postmenopausal women). In addition, she showed a 33% greater skeletal muscle mass index when compared with healthy, older female control subjects (7.9 vs. 5.9 [5.7-6.2] kg/m2; n = 61) as well as 37% greater muscle quadriceps CSA (63.8 vs. 46.6 [44.5-48.7] cm2; n = 48) and 46% greater Type II muscle fiber CSA (4,536 vs. 3,097 [2,707-3,488] µm2; n = 19). Absolute leg press muscle strength was 36% greater (190 vs. 140 [132-147] kg; n = 30) and handgrip strength was 33% greater (33 vs. 25 [23-26] kg; n = 48) when compared with healthy, age-matched controls. In conclusion, even for resistance exercise naïve individuals, starting exercise at an advanced age can lead to improvements in body composition and muscle strength allowing older adults to reduce the risk for developing metabolic syndrome, live independently, and even compete at a world class level.

The muscle protein synthetic response following corn protein ingestion does not differ from milk protein in healthy, young adults.

Plant-derived proteins are generally believed to possess lesser anabolic properties when compared with animal-derived proteins. This is, at least partly, attributed to the lower leucine content of most plant-derived proteins. Corn protein has a leucine content that is highest among most plant-derived proteins and it even exceeds the levels observed in animal-derived proteins such as whey protein. Therefore, this study aimed to compare muscle protein synthesis rates following the ingestion of 30 g corn protein and a 30 g blend of corn plus milk protein with 30 g milk protein. In a randomized, double blind, parallel-group design, 36 healthy young males (26 ± 4 y) received primed continuous L-[ring-13C6]-phenylalanine infusions and ingested 30 g corn protein (CORN), 30 g milk protein (MILK), or a 30 g proteinblend with 15 g corn plus 15 g milk protein (CORN + MILK). Blood and muscle biopsies were collected for 5 h following protein ingestion to assess post-prandial plasma amino acid profiles and myofibrillar protein synthesis rates. The results show that Ingestion of protein increased myofibrillar protein synthesis rates from basal post-absorptive values in all treatments(P < 0.001). Post-prandial myofibrillar protein synthesis rates did not differ between CORN vs MILK (0.053 ± 0.013 vs 0.053 ± 0.013%∙h-1, respectively; t-test P = 0.90), or between CORN + MILK vs MILK (0.052 ± 0.024 vs 0.053 ± 0.013%∙h-1, respectively; t-test P = 0.92). Ingestion of 30 g corn protein, 30 g milk protein, or a blend of 15 g corn plus 15 g milk protein robustly increases muscle protein synthesis rates in young males. The muscle protein synthetic response to the ingestion of 30 g corn-derived protein does not differ from the ingestion of an equivalent amount of milk protein in healthy, young males. Clinical Trial Registry number. NTR6548 (registration date: 27-06-2017) https://www.trialregister.nl/ .

Daily blood flow restriction does not preserve muscle mass and strength during 2 weeks of bed rest.

We measured the impact of blood flow restriction on muscle protein synthesis rates, muscle mass and strength during 2 weeks of strict bed rest. Twelve healthy, male adults (age: 24 ± 3 years, body mass index: 23.7 ± 3.1 kg/m2 ) were subjected to 14 days of strict bed rest with unilateral blood flow restriction performed three times daily in three 5 min cycles (200 mmHg). Participants consumed deuterium oxide and we collected blood and saliva samples throughout 2 weeks of bed rest. Before and immediately after bed rest, lean body mass (dual-energy X-ray absorptiometry scan) and thigh muscle volume (magnetic resonance imaging scan) were assessed in both the blood flow restricted (BFR) and control (CON) leg. Muscle biopsies were collected and unilateral muscle strength (one-repetition maximum; 1RM) was assessed for both legs before and after the bed rest period. Bed rest resulted in 1.8 ± 1.0 kg lean body mass loss (P < 0.001). Thigh muscle volume declined from 7.1 ± 1.1 to 6.7 ± 1.0 L in CON and from 7.0 ± 1.1 to 6.7 ± 1.0 L in BFR (P < 0.001), with no differences between treatments (P = 0.497). In addition, 1RM leg extension strength decreased from 60.2 ± 10.6 to 54.8 ± 10.9 kg in CON and from 59.2 ± 12.1 to 52.9 ± 12.0 kg in BFR (P = 0.014), with no differences between treatments (P = 0.594). Muscle protein synthesis rates during bed rest did not differ between the BFR and CON leg (1.11 ± 0.12 vs. 1.08 ± 0.13%/day, respectively; P = 0.302). Two weeks of bed rest substantially reduces skeletal muscle mass and strength. Blood flow restriction during bed rest does not modulate daily muscle protein synthesis rates and does not preserve muscle mass or strength. KEY POINTS: Bed rest, often necessary for recovery from illness or injury, leads to the loss of muscle mass and strength. It has been postulated that blood flow restriction may attenuate the loss of muscle mass and strength during bed rest. We investigated the effect of blood flow restriction on muscle protein synthesis rates, muscle mass and strength during 2 weeks of strict bed rest. Blood flow restriction applied during bed rest does not modulate daily muscle protein synthesis rates and does not preserve muscle mass or strength. Blood flow restriction is not effective in preventing muscle atrophy during a prolonged period of bed rest.

Post-prandial muscle protein synthesis rates following the ingestion of pea-derived protein do not differ from ingesting an equivalent amount of milk-derived protein in healthy, young males.

PURPOSE: Plant-derived proteins have received considerable attention as an alternative to animal-derived proteins. However, plant-derived proteins are considered to have less anabolic properties when compared with animal-derived proteins. The lower muscle protein synthesis rates following ingestion of plant- compared with animal-derived protein have been attributed to the lower essential amino acid content of plant-derived proteins and/or their specific amino acid deficiencies. This study aimed to compare post-prandial muscle protein synthesis rates following the ingestion of 30 g pea-derived protein with 30 g milk-derived protein in healthy, young males. METHODS: In a randomized, double-blind, parallel-group design, 24 young males (24 ± 3 y) received a primed continuous L-[ring-13C6]-phenylalanine infusion after which they ingested 30 g pea (PEA) or 30 g milk-derived protein (MILK). Blood and muscle biopsies were collected frequently for 5 h to assess post-prandial plasma amino acid profiles and subsequent post-prandial muscle protein synthesis rates. RESULTS: MILK increased plasma essential amino acid concentrations more than PEA over the 5 h post-prandial period (incremental area under curve 151 ± 31 vs 102 ± 15 mmol∙300 min∙L-1, respectively; P < 0.001). Ingestion of both MILK and PEA showed a robust muscle protein synthetic response with no significant differences between treatments (0.053 ± 0.013 and 0.053 ± 0.017%∙h-1, respectively; P = 0.96). CONCLUSION: Post-prandial muscle protein synthesis rates following the ingestion of 30 g pea-derived protein do not differ from the response following ingestion of an equivalent amount of milk-derived protein. International Clinical Trials Registry Platform (NTR6548; 27-06-2017).

Energy Requirements of Paralympic Athletes: Insights from the Doubly Labeled Water Approach.

PURPOSE: Advanced insight in energy requirements of Paralympic athletes is imperative for optimizing their nutritional counseling. Given the lack of accurate data on total daily energy expenditure (TDEE) of Paralympic athletes, this study aimed to assess energy expenditure and nutritional intake of a large cohort of Paralympic athletes, across different sports and disabilities. METHODS: In this cross-sectional study, 48 Dutch and Norwegian Paralympic athletes (19 male/29 female) with various disabilities, competing in Para cycling, wheelchair tennis, wheelchair basketball, Para Nordic skiing, and alpine skiing participated. TDEE was assessed by the gold standard doubly labeled water method over a 14-d period, resting metabolic rate by ventilated hood indirect calorimetry, energy intake by three unannounced 24-h dietary recalls, body composition by dual-energy x-ray absorptiometry, and exercise training duration by a training log. RESULTS: Mean TDEE was 2908 ± 797 kcal·d -1 , ranging from 2322 ± 340 kcal·d -1 for wheelchair basketball players to 3607 ± 1001 kcal·d -1 for Para cyclists. Regression analysis identified fat-free mass, exercise duration, and the presence of a spinal cord disorder as the primary predictors of TDEE, explaining up to 73% of the variance in TDEE. Athletes' energy intake (2363 ± 905 kcal·d -1 ) was below their TDEE, whereas their body mass remained constant, indicating underreporting. Carbohydrate intake (4.1 ± 1.9 g·kg -1 body mass) was low, even when considering underreporting, whereas protein intake (1.8 ± 0.6 g·kg -1 body mass) was relatively high. CONCLUSIONS: Paralympic athletes display moderate- to high-energy expenditure, varying across sports and individuals. Much of the variation in TDEE can be attributed to individual differences in fat-free mass and exercise duration. This study establishes the benchmarks for energy requirements of Paralympic athletes, serving as the foundation for future dietary guidelines within this population.

A Low or High Physical Activity Level Does Not Modulate Prostate Tumor Tissue Protein Synthesis Rates.

INTRODUCTION: Physical activity level has been identified as an important factor in the development and progression of various types of cancer. In this study, we determined the impact of a low versus high physical activity level on skeletal muscle, healthy prostate, and prostate tumor protein synthesis rates in vivo in prostate cancer patients. METHODS: Thirty prostate cancer patients (age, 66 ± 5 yr; body mass index, 27.4 ± 2.9 kg·m -2 ) were randomized to a low (<4000 steps per day, n = 15) or high (>14,000 steps per day, n = 15) physical activity level for 7 d before their scheduled radical prostatectomy. Daily deuterium oxide administration was combined with the collection of plasma, skeletal muscle, nontumorous prostate, and prostate tumor tissue during the surgical procedure to determine tissue protein synthesis rates throughout the intervention period. RESULTS: Daily step counts averaged 3610 ± 878 and 17,589 ± 4680 steps in patients subjected to the low and high physical activity levels, respectively ( P < 0.001). No differences were observed between tissue protein synthesis rates of skeletal muscle, healthy prostate, or prostate tumor between the low (1.47% ± 0.21%, 2.74% ± 0.70%, and 4.76% ± 1.23% per day, respectively) and high (1.42% ± 0.16%, 2.64% ± 0.58%, and 4.72% ± 0.80% per day, respectively) physical activity group (all P > 0.4). Tissue protein synthesis rates were nearly twofold higher in prostate tumor compared with nontumorous prostate tissue. CONCLUSIONS: A short-term high or low physical activity level does not modulate prostate or prostate tumor protein synthesis rates in vivo in prostate cancer patients. More studies on the impact of physical activity level on tumor protein synthesis rates and tumor progression are warranted to understand the potential impact of lifestyle interventions in the prevention and treatment of cancer.

Graded Replacement of Carbohydrate-Rich Breakfast Products with Dairy Products: Effects on Postprandial Aminoacidemia, Glycemic Control, Bone Metabolism, and Satiety.

BACKGROUND: Postprandial metabolic responses following dairy consumption have mostly been studied using stand-alone dairy products or milk-derived nutrients. OBJECTIVE: Assessing the impact of ingesting dairy products as part of a common breakfast on postprandial aminoacidemia, glycemic control, markers of bone metabolism, and satiety. METHODS: In this randomized, crossover study, 20 healthy young males and females consumed on 3 separate occasions an iso-energetic breakfast containing no dairy (NO-D), 1 dairy (ONE-D), or 2 dairy (TWO-D) products. Postprandial concentrations of amino acids, glucose, insulin, glucagon-like peptide-1 (GLP-1), calcium, parathyroid hormone (PTH), and markers of bone formation (P1NP) and resorption (CTX-I) were measured before and up to 300 min after initiating the breakfast, along with VAS-scales to assess satiety. RESULTS: Plasma essential and branched-chained amino acids availability (expressed as total area under the curve (tAUC)) increased in a dose-dependent manner (P<0.05 for all comparisons). Plasma glucose tAUCs were lower in ONE-D and TWO-D compared with NO-D (P<0.05 for both comparisons). Plasma GLP-1 tAUC increased in a dose-dependent manner (P<0.05 for all comparisons), whereas no differences were observed in plasma insulin tAUC between conditions (P>0.05 for all comparisons). Serum calcium tAUCs were higher in ONE-D and TWO-D compared with NO-D (P<0.05 for both comparisons), along with lower PTH tAUCs in ONE-D and TWO-D compared with NO-D (P=0.001 for both comparisons). In accordance, serum CTX-I concentrations were lower in the late postprandial period in ONE-D and TWO-D compared with NO-D (P<0.01 for both comparisons). No differences were observed in P1NP tAUCs between conditions (P>0.05). The tAUC for satiety was higher in TWO-D compared with NO-D and ONE-D (P<0.05 for both comparisons). CONCLUSIONS: Iso-energetic replacement of a carbohydrate-rich breakfast component with one serving of dairy improves postprandial amino acid availability, glycemic control, and bone metabolism. Adding a second serving of dairy in lieu of carbohydrates augments postprandial amino acid and GLP-1 concentrations while further promoting satiety. This study was registered at https://doi.org/10.1186/ISRCTN13531586 with Clinical Trial Registry number ISRCTN13531586.

Jumping Exercise Combined With Collagen Supplementation Preserves Bone Mineral Density in Elite Cyclists.

This study assessed the effect of combined jump training and collagen supplementation on bone mineral density (BMD) in elite road-race cyclists. In this open-label, randomized study with two parallel groups, 36 young (21 ± 3 years) male (n = 8) and female (n = 28) elite road-race cyclists were allocated to either an intervention (INT: n = 18) or a no-treatment control (CON: n = 18) group. The 18-week intervention period, conducted during the off-season, comprised five 5-min bouts of jumping exercise per week, with each bout preceded by the ingestion of 15 g hydrolyzed collagen. Before and after the intervention, BMD of various skeletal sites and trabecular bone score of the lumbar spine were assessed by dual-energy X-ray absorptiometry, along with serum bone turnover markers procollagen Type I N propeptide and carboxy-terminal cross-linking telopeptide of Type I collagen. BMD of the femoral neck decreased in CON (from 0.789 ± 0.104 to 0.774 ± 0.095 g/cm2), while being preserved in INT (from 0.803 ± 0.058 to 0.809 ± 0.066 g/cm2; Time × Treatment, p < .01). No differences between treatments were observed for changes in BMD at the total hip, lumbar spine, and whole body (Time × Treatment, p > .05 for all). Trabecular bone score increased from 1.38 ± 0.08 to 1.40 ± 0.09 in CON and from 1.46 ± 0.08 to 1.47 ± 0.08 in INT, respectively (time effect: p < .01), with no differences between treatments (Time × Treatment: p = .33). Serum procollagen Type I N propeptide concentrations decreased to a similar extent in CON (83.6 ± 24.8 to 71.4 ± 23.1 ng/ml) and INT (82.8 ± 30.7 to 66.3 ± 30.6; time effect, p < .001; Time × Treatment, p = .22). Serum carboxy-terminal cross-linking telopeptide of Type I collagen concentrations did not change over time, with no differences between treatments (time effect, p = .08; Time × Treatment, p = .58). In conclusion, frequent short bouts of jumping exercise combined with collagen supplementation beneficially affects femoral neck BMD in elite road-race cyclists.

One Week of Single-Leg Immobilization Lowers Muscle Connective Protein Synthesis Rates in Healthy, Young Adults.

PURPOSE: Short periods of limb immobilization lower myofibrillar protein synthesis rates. Within skeletal muscle, the extracellular matrix of connective proteins is recognized as an important factor determining the capacity to transmit contractile force. Little is known regarding the impact of immobilization and subsequent recovery on muscle connective protein synthesis rates. This study examined the impact of 1 wk of leg immobilization and 2 wk of subsequent ambulant recovery on daily muscle connective protein synthesis rates. METHODS: Thirty healthy, young (24 ± 5 yr) men were subjected to 7 d of one-legged knee immobilization followed by 14 d of ambulant recovery. Deuterium oxide ingestion was applied over the entire period, and muscle biopsy samples were collected before immobilization, after immobilization, and after recovery to measure muscle connective protein synthesis rates and mRNA expression of key extracellular matrix proteins (collagen I, collagen III), glycoproteins (fibronectin, tenascin-C), and proteoglycans (fibromodulin, and decorin). A two-way repeated-measures (time-leg) ANOVA was used to compare changes in muscle connective protein synthesis rates during immobilization and recovery. RESULTS: During immobilization, muscle connective protein synthesis rates were lower in the immobilized (1.07 ± 0.30%·d -1 ) compared with the nonimmobilized (1.48 ± 0.44%·d -1 ; P < 0.01) leg. When compared with the immobilization period, connective protein synthesis rates in the immobilized leg increased during subsequent recovery (1.48 ± 0.64%·d -1 ; P < 0.01). After recovery, skeletal muscle collagen I, collagen III, fibronectin, fibromodulin, and decorin mRNA expression increased when compared with the postimmobilization time point (all P < 0.001). CONCLUSIONS: One week of leg immobilization lowers muscle connective protein synthesis rates. Muscle connective protein synthesis rates increase during subsequent ambulant recovery, which is accompanied by increased mRNA expression of key extracellular matrix proteins.

Muscle Mass and Strength Gains Following Resistance Exercise Training in Older Adults 65-75 Years and Older Adults Above 85 Years.

Resistance exercise training (RET) can be applied effectively to increase muscle mass and function in older adults (65-75 years). However, it has been speculated that older adults above 85 years are less responsive to the benefits of RET. This study compares the impact of RET on muscle mass and function in healthy older adults 65-75 years versus older adults above 85 years. We subjected 17 healthy older adults 65-75 years (OLDER 65-75, n = 13/4 [female/male]; 68 ± 2 years; 26.9 ± 2.3 kg/m2) and 12 healthy older adults above 85 years (OLDER 85+, n = 7/5 [female/male]; 87 ± 3 years; 26.0 ± 3.6 kg/m2) to 12 weeks of whole-body RET (three times per week). Prior to, and after 6 and 12 weeks of training, quadriceps and lumbar spine vertebra 3 muscle cross-sectional area (computed tomography scan), whole-body lean mass (dual-energy X-ray absorptiometry scan), strength (one-repetition maximum test), and physical performance (timed up and go and short physical performance battery) were assessed. Twelve weeks of RET resulted in a 10% ± 4% and 11% ± 5% increase in quadriceps cross-sectional area (from 46.5 ± 10.7 to 51.1 ± 12.1 cm2, and from 38.9 ± 6.1 to 43.1 ± 8.0 cm2, respectively; p < .001; η2 = .67); a 2% ± 3% and 2% ± 3% increase in whole-body lean mass (p = .001; η2 = .22); and a 38% ± 20% and 46% ± 14% increase in one-repetition maximum leg extension strength (p < .001; η2 = .77) in the OLDER 65-75 and OLDER 85+ groups, respectively. No differences in the responses to RET were observed between groups (Time × Group, all p > .60; all η2 ≤ .012). Physical performance on the short physical performance battery and timed up and go improved (both p < .01; η2 ≥ .22), with no differences between groups (Time × Group, p > .015; η2 ≤ .07). Prolonged RET increases muscle mass, strength, and physical performance in the aging population, with no differences between 65-75 years and 85+ years older adults.

Resistance Exercise Training, a Simple Intervention to Preserve Muscle Mass and Strength in Prostate Cancer Patients on Androgen Deprivation Therapy.

Androgen deprivation therapy (ADT) forms the cornerstone in the treatment of advanced prostate cancer. However, by suppressing testosterone ADT results in a decrease of skeletal muscle mass. In this narrative review, we explore the magnitude and mechanisms of ADT-induced muscle mass loss and the consequences for muscle strength and physical performance. Subsequently, we elucidate the effectiveness of supervised resistance exercise training as a means to mitigate these adverse effects. Literature shows that resistance exercise training can effectively counteract ADT-induced loss of appendicular lean body mass and decline in muscle strength, while the effect on physical performances is inconclusive. As resistance exercise training is feasible and can be safely implemented during ADT (with special attention for patients with bone metastases), it should be incorporated in standard clinical care for prostate cancer patients (starting) with ADT.

Administration of Free Amino Acids Improves Exogenous Amino Acid Availability when Compared with Intact Protein in Critically Ill Patients: A Randomized Controlled Study.

BACKGROUND: Protein digestion and amino acid absorption appear compromised in critical illness. The provision of enteral feeds with free amino acids rather than intact protein may improve postprandial amino acid availability. OBJECTIVE: Our objective was to quantify the uptake of diet-derived phenylalanine after the enteral administration of intact protein compared with an equivalent amount of free amino acids in critically ill patients. METHODS: Sixteen patients who were mechanically ventilated in intensive care unit (ICU) at risk of malabsorption received a primed continuous infusion of L-[ring-2H5]-phenylalanine and L-[ring-3,5-2H2]-tyrosine after an overnight fast. Patients were randomly allocated to receive 20 g intrinsically L-[1-13C]-phenylalanine-labeled milk protein or an equivalent amount of amino acids labeled with free L-[1-13C]-phenylalanine via a nasogastric tube over a 2-h period. Protein digestion and amino acid absorption kinetics and whole-body protein net balance were assessed throughout a 6-h period. RESULTS: After enteral nutrient infusion, both plasma phenylalanine and leucine concentrations increased (P-time < 0.001), with a more rapid and greater rise after free amino acid compared with intact protein administration (P-time × treatment = 0.003). Diet-derived phenylalanine released into the circulation was 25% greater after free amino acids compared with intact protein administration [68.7% (confidence interval {CI}: 62.3, 75.1%) compared with 43.8% (CI: 32.4, 55.2%), respectively; P < 0.001]. Whole-body protein net balance became positive after nutrient administration (P-time < 0.001) and tended to be more positive after free amino acid in provision (P-time × treatment = 0.07). CONCLUSIONS: The administration of free amino acids as opposed to intact protein further increases postprandial plasma amino acid availability in critically ill patients, allowing more diet-derived phenylalanine to become available to peripheral tissues. This trial was registered at clinicaltrials.gov as NCT04791774.