Whey Protein (Post-workout)

The aim of the current parallel randomized controlled trial was to compare the effects of ingesting a dietary supplement admixture providing carbohydrates, leucine-fortified whey protein, creatine, β-hydroxy-β-methylbutyrate, and vitamin D3 (Master Recovery 1:1, Crown Sport Nutrition, Spain), versus an isoenergetic carbohydrate-only comparator on body composition, muscle thickness, muscle strength, and performance over a 6-week resistance training program, performed three times per week, in aging, physically active individuals. Twenty participants (10 peri- and post-menopausal females and 10 males) -completed the study after being randomly assigned to one of the following groups: post-workout multi-ingredient (PWS: n = 10, 52.0 ± 5 years, body mass 82.0 ± 18.0 kg) or a comparator (COM: n = 10, 51 ± 3 years, body mass 85.9 ± 17.0 kg). Treatment consisted of ingesting 60.0 g of the assigned supplement immediately after each workout. Compared to baseline, only PWS increased fat-free mass (+1.34 ± 1.2 kg, p = 0.003), reduced fat mass (-1.09 ± 0.7 kg, p < 0.001), waist circumference (-2.5 ± 1.8 cm, p < 0.001), and waist-to-hip ratio (-0.03 ± 0.03 cm, p = 0.007). At post-intervention, waist circumference reduction was different between groups (p = 0.02, d = 1.19). Both treatments similarly improved vastus lateralis and elbow flexor thickness, medicine ball throw, and endurance performance. Although countermovement jump improved for both treatments, the PWS group showed a significantly higher performance increase compared to COM (p < 0.01, d = 1.47). Compared to ingesting carbohydrates only, the use of a targeted multi-ingredient promoted noticeable body composition outcomes and better vertical jump improvements with no further effects on hypertrophy, upper body, and endurance performance. The study was registered as a clinical trial at ClinicalTrials.gov (NCT05769088).

Objectives: The aim of this study was to explore the combined effects of resistance exercise and whey protein supplementation on plasma irisin levels in patients with metabolic dysfunction-associated steatotic liver disease (MASLD) under a 30% calorie-restricted weight loss diet. Methods: Thirty adult patients with MASLD were randomized into the following three groups for a 4-week intervention: calorie restriction group (CR) (n = 8), CR with resistance exercise group (EX) (n = 11), and CR with resistance exercise and whey protein group (EX + P) (n = 11; 0.7 g/kg per day). All participants received boxed meals providing 70% of their total energy expenditure. The participants in the resistance exercise groups performed full-body resistance exercises 5 days/week (50-75% one-repetition maximum). Plasma irisin level, controlled attenuation parameter (CAP), and body composition were assessed before and after the intervention. Results: Plasma irisin levels significantly increased in the EX (+2.24 ng/mL, p = 0.016) and EX + P (+4.86 ng/mL, p = 0.004) groups but not in the CR group. Muscle mass increased significantly only in the EX + P group. The CAP decreased in all groups. The change in irisin level was negatively correlated with the change in CAP (r = -0.459, p = 0.032). Conclusions: Resistance exercise under calorie-restricted conditions effectively increased plasma irisin levels in patients with MASLD, whereas caloric restriction alone did not. Furthermore, a stronger increasing trend in the plasma irisin levels was observed with whey protein supplementation. An increase in irisin levels was significantly associated with hepatic fat reduction, suggesting that irisin may serve as a biomarker reflecting improvements in hepatic steatosis following lifestyle intervention.

BACKGROUND: High‑protein diets are widely used by athletes but may disturb the gut environment and increase production of odor‑related metabolites. Probiotic supplementation has been proposed as a strategy to support gastrointestinal function under such dietary stress. This study aimed to explore the effects of Bifidobacterium longum BB536 on gastrointestinal symptoms, gut microbiota, and odor‑related metabolites in male athletes consuming a high‑protein diet. METHODS: In an exploratory, randomized, double‑blind, placebo‑controlled trial, 60 healthy male athletes (mean age: 18.62 ± 0.75 years; mean BMI: 22.35 ± 1.80 kg/m2) consumed a whey protein supplement (70 g/day) together with either BB536 (46 billion CFU/day, as measured at the start of the intervention) or placebo for 4 weeks. Gastrointestinal symptoms, gut microbiota composition, skin‑emitted volatile compounds, and fecal metabolites were assessed. Subgroup analyses based on responder status and baseline enterotype were conducted post hoc to generate hypotheses regarding microbiota‑dependent responses. RESULTS: In the overall cohort, no significant between‑group differences were observed across gastrointestinal outcomes, gut microbiota indices, or metabolite profiles. Within the BB536 group, diarrhea‑related scores improved from baseline. Post hoc analyses suggested that increases in Faecalibacterium were evident among responders. Enterotype‑based patterns also emerged: individuals with Ruminococcus‑dominant microbiota showed higher skin‑emitted short‑chain fatty acids after BB536 intake, whereas those with Faecalibacterium‑dominant microbiota exhibited reductions in odor‑related metabolites, including methyl mercaptan and ammonia. Corresponding fecal metabolite shifts were modest. CONCLUSION: BB536 supplementation was associated with improvements in diarrhea‑related symptoms and odor‑related metabolites in specific microbiota‑defined subgroups. As these findings did not extend to the full cohort, they should be interpreted as exploratory and hypothesis‑generating. Baseline gut microbiota composition may influence probiotic responsiveness, warranting confirmatory trials with prespecified endpoints.

PURPOSE: Aging and sarcopenia are associated with metabolic inflexibility. This study investigated the effects of resistance exercise (RE) and a high protein diet (PRO) on metabolic flexibility (the ability to adjust rates of substrate oxidation to changes in fuel availability) in older men. METHODS: In a pooled groups analysis, 33 healthy older men [(mean±SE) age: 67±1 years; BMI: 25.4±0.4 kg/m2] were randomized to either RE (2×/week; n=17) or no exercise (NE; n=16), and either high protein diet [∼1.6 g/kg/day (∼25% of energy intake (EI))] via twice daily (25 g) whey protein supplementation (PRO; n=17) or control (CON, 2 × 23.75 g maltodextrin/day; n=16). An exploratory sub-analysis was also conducted between RE+CON (n=8) and RE+PRO (n=9). At baseline and 12 weeks, participants resided in whole-room indirect calorimeters for 24 h for measurement of metabolic flexibility via changes in relative substrate utilization [non-protein respiratory quotient (npRQ)] under different conditions (fasting sleep to awake, step exercise, and 2-h postprandial meal consumption, and peak step exercise to exercise end). RESULTS: Compared to NE, RE significantly increased (indicating medium-to-large effects on improved metabolic flexibility) ΔnpRQ (awake-sleep) (+0.02±0.004 vs. 0.00±0.05, p=0.01, f=0.48), and ΔnpRQ (steady state exercise-sleep) (p ≤0.045) and ΔnpRQ (peak exercise-exercise end) (p ≤0.04, f=0.39-0.64) for two step exercise bouts performed ∼2 h postprandially. Compared to CON, PRO increased ΔnpRQ (steady state-sleep) for one step exercise bout (+0.02±0.01 vs. -0.002±0.01, p=0.047, f=0.39). No significant differences occurred between the RE+CON and RE+PRO groups (p ≥0.06). CONCLUSION: In older men, RE improved metabolic flexibility. PRO had a limited benefit. No synergistic effects were observed.

BACKGROUND/OBJECTIVES: The primary outcome of this 8-week randomized, controlled, parallel trial was to assess longitudinal shifts in gut microbiota structure and predicted metabolic potential in 45 elite football players following protein supplementation. METHODS: Participants combined resistance training with daily intake (30 g) of whey protein concentrate (WPC), pea protein isolate (PPI), rice protein isolate (RPI), or a plant-protein blend (MIX). For the acquisition of prokaryotic metataxonomic data, the V3-V8 region of the 16S rRNA gene was sequenced using Oxford Nanopore Technology (ONT). Functional potential was inferred through the MACADAM database and STAMP software. Strict dietary monitoring and gravimetric adherence checks were performed to isolate the intervention effect. RESULTS: While microbial alpha-diversity indices (Chao1, Shannon, Simpson) remained stable across all groups, significant source-specific shifts in taxonomic structure and predicted metabolic activity were identified. Whey protein concentrate (WPC) was associated with an increase in Bacteroidetes abundance and greater balance within the microbial community structure, whereas pea protein isolate (PPI) and the MIX correlated with reduced fermentative bacteria and elevated taxa potentially involved in cadaverine biosynthesis. Rice protein isolate (RPI) supplementation was associated with a higher predicted representation of taxa involved in succinate-to-butyrate fermentation pathways. These functional markers and differential responses of selected bacterial groups to particular protein types were observed. CONCLUSIONS: The data indicate complex interactions between supplement type, exposure duration, and microbiome response, underscoring the necessity for individualized dietary recommendations and supplementation strategies to optimize gut health and training adaptation in professional football players.

This study investigated the acute effects of different protein sources consumed at sahur on anaerobic power and strength performances in trained male combat sport athletes during Ramadan fasting. Using a single blind, randomized, placebo-controlled, counterbalanced crossover study design, 24 male combat sports' athletes (mean age: 27.3 ± 3.8 years, Tier 3 national level) completed four experimental conditions: (1) non-fasting control, (2) fasting + placebo (maltodextrin), (3) fasting + whey protein isolate (WPI), and (4) fasting + micellar casein (MC). In each condition, a standardized sahur meal (6.3-7.7 kcal/kg body weight) and supplementation (0.4 g/kg for WPI/MC and 0.4 g/kg for Placebo) were administered. Physical Performances was assessed 11-13 hours post-sahur (or 3-5 hours post-lunch for control) including the Wingate anaerobic test, bench press, leg press, and countermovement jump (CMJ), and handgrip strength tests. Ramadan fasting significantly lowered Wingate peak power, mean power, and bench press strength compared to the non-fasting control. MC supplementation reduced these declines, outperforming WPI and the placebo in peak power and mean power, and surpassing the placebo in bench press strength, although not WPI. Leg press, countermovement jump, and handgrip strength showed no significant differences across conditions. MC supplementation at sahur provides partial protection against fasting-induced declines in anaerobic power and upper body endurance, but does not fully restore performance to non-fasting levels. These findings emphasize the importance of protein timing and selection in mitigating performance decrements during Ramadan fasting, highlighting the need for further research on optimal nutritional strategies for athletes training and competing under fasting conditions. Copyright: © 2026 Demirli et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

As the global population ages, frailty and sarcopenia have emerged as pressing public health challenges due to their impact on functional decline and increased health care burden. This study assessed the efficacy of lactic acid bacteria-fermented whey protein (LAB-FWP) supplementation for improving physical function and nutritional markers in community-dwelling older Korean adults. A total of 45 individuals aged 65 years and older (body mass index 18.5-30) who had not used protein supplements in the prior 6 months were enrolled in a 10-week, randomized, blinded trial. Participants were assigned to either the intervention group (n = 22), which received 38 g/day of LAB-FWP, or the control group (n = 23), which received a taste- and texture-matched dextrin placebo. The intervention group demonstrated significant improvements in physical performance, including an increase in electronic Short Physical Performance Battery (eSPPB) scores (P = .034) and hand grip strength (P = .043). Nutritional biomarkers also improved markedly: dietary vitamin D intake increased from 2.2 to 11.6 µg, calcium intake from 280.9 to 566.7 mg, and magnesium intake from 135.5 to 316.3 mg (all P < .001). Compared with controls, the intervention group showed greater gains in skeletal muscle mass index (Δ = 1.5, P = .004) and eSPPB scores (Δ = 1.4, P = .017). Regression analysis revealed that physical function was positively associated with improvements in nutrition. Daily supplementation with LAB-FWP led to clinically meaningful enhancements in both functional capacity and nutritional status, suggesting its potential as a practical strategy to mitigate age-related frailty and sarcopenia.

BACKGROUND & AIMS: Dietary anti-inflammatory interventions have shown promise in the prevention and management of sarcopenia. However, the efficacy of various anti-inflammatory diets/supplements in improving muscle strength, mass, and physical performance in patients with sarcopenia remains unclear. The objective of this study was to systematically assess the efficacy of various anti-inflammatory supplements in alleviating symptoms in patients with sarcopenia, thereby providing robust evidence to inform clinical practice and nutritional recommendations. METHODS: This study systematically searched 11 Chinese and English databases in August 2025 to include randomized controlled trials (RCTs) evaluating the intervention effects of anti-inflammatory diets or supplements on elderly patients with sarcopenia. Primary outcomes included handgrip strength, gait speed, the five times sit-to-stand test (FTSST), and the appendicular skeletal muscle mass index (ASMI). Secondary outcomes included the Short Physical Performance Battery (SPPB) score, fat-free mass (FFM), and laboratory parameters (triglycerides, high-density lipoprotein, low-density lipoprotein, and C-reactive protein). For primary outcomes, both pairwise and network meta-analyses were performed to compare the effects of different interventions. For secondary outcomes, only pairwise meta-analysis was conducted. RESULTS: Finally, 42 randomized controlled trials were included, involving 3063 elderly patients with sarcopenia, covering seven categories of anti-inflammatory supplements: combined supplements (combinations of at least two anti-inflammatory supplements), amino acids, whey protein, β-Hydroxy-β-methylbutyrate (HMB), Vitamin D, n-3 polyunsaturated fatty acids (PUFAs), and epicatechin. Network meta-analysis results indicated that whey protein (SMD=0.78, 95% CI: 0.07, 1.48), vitamin D (SMD=1.44, 95% CI: 0.76, 2.11), and Epicatechin (SMD=2.44, 95% CI: 1.69, 3.18) are the most effective measures to improve handgrip strength, gait speed, and ASMI, respectively. For FTSST, a significant improvement was only found for combined supplements in the pairwise meta-analysis (SMD = -0.34, 95% CI: -0.63, -0.05). Notably,

BACKGROUND: Aging is accompanied by reduced muscle protein synthesis and increased circulating acid, both of which contribute to declines in muscle health. OBJECTIVES: To determine the effects of whey protein (WP) and alkali (potassium bicarbonate, KHCO3) supplementation on muscle performance and mass in healthy older adults. METHODS: In this randomized, 2 × 2 factorial, placebo-controlled study, healthy adults aged ≥65 years were assigned to either WP (1.5 g/kg/d) plus KHCO3 (81 mmol/d), WP plus placebo-KHCO3, placebo-WP plus KHCO3, or double placebo. Double leg press muscle power (primary outcome), physical performance, lean mass by dual energy x-ray absorptiometry, muscle mass by D3-creatine dilution, and serum insulin-like growth factor 1 (IGF-1) were measured at baseline and 24 weeks. Primary analyses estimated main effects of WP compared with placebo-WP and KHCO3 compared with placebo-KHCO3 using factorial comparisons "at-the-margins," following CONSORT/SPIRIT recommendations for factorial trials. Between-group differences in the 24-wk outcomes were estimated using analysis of covariance adjusted for baseline value, age, and sex. RESULTS: In the intention-to-treat sample (n = 128), 47.7% were female, mean ± SD age was 74 ± 6 y, and baseline protein intake was 0.85 ± 0.30 g/kg/d. Neither WP nor KHCO3 affected muscle power compared with their respective placebo {WP to placebo-WP difference 4.7 watts [95% confidence interval (CI): -21.1,30.5; P = 0.72]; KHCO3 to placebo-KHCO3 difference -13.6 watts [95% CI: -39.6, 12.4; P = 0.30]}. No group differences were noted in physical performance or muscle mass. However, 24-wk mean IGF-1 level was higher in the WP and KHCO3 groups compared with their respective placebo [WP to placebo-WP difference 14.2 ng/mL (95% CI: 7.5, 21.0; P < 0.01); KHCO3 to placebo-KHCO3 difference 7.2 ng/mL (95% CI: 0.4, 13.9; P = 0.04)]. CONCLUSIONS: In healthy free-living older adults reporting a protein intake at the current recommended daily allowance, neither increasing protein to 1.5 g/kg/d with WP nor adding a KHCO3 supplement for 24 wk improved measures of muscle power, physical performance, or muscle mass despite achieving higher circu

Background: Obesity is traditionally defined by excess fat mass; however, the preservation of fat-free mass (FFM), particularly skeletal muscle, has gained increasing relevance due to its metabolic, endocrine, and functional roles. Weight loss interventions, including hypocaloric diets, pharmacological treatments, and bariatric surgery, are frequently associated with unintended loss of skeletal mass, increasing the risk of sarcopenic obesity and related complications. Objective: This study aimed to systematically evaluate the effectiveness of whey protein supplementation in preserving fat-free mass and muscle-related outcomes in adults with obesity undergoing weight loss interventions. Methods: A systematic review was conducted in accordance with PRISMA guidelines. Randomized controlled trials published in English were identified through searches of PubMed/MEDLINE, CENTRAL, Embase, Scopus, ClinicalTrials.gov, and WHO ICTRP, searched up to September 2025. Eligible studies included adults (>18 years) with obesity receiving whey protein supplementation as part of a hypocaloric diet, compared with placebo or standard interventions. Primary outcomes were changes in fat-free mass assessed by validated methods (DXA, BIA, MRI), while secondary outcomes included body weight, fat mass, metabolic parameters, adherence, and safety. Risk of bias was assessed using the Cochrane RoB 2.0 tool, and certainty of evidence was evaluated with GRADE. The abstract was registered in PROSPERO with code CRD420251069996. There was no funding and no conflicts of interest. Results: Fourteen randomized controlled trials were included. Whey protein supplementation generally supported the maintenance or modest improvement of fat-free mass, particularly when combined with resistance exercise or anabolic-enriched formulations such as leucine or vitamin D. Several trials, however, reported neutral effects, especially in the absence of structured physical activity. Overall, effect estimates ranged from small gains to null or uncertain differences, and the certainty of evidence was frequently downgraded due to limited sample sizes, wide confidence intervals, heterogeneity across interventions and a

OBJECTIVE: Postprandial stimulation of muscle protein synthesis depends on intracellular amino acid (AA) availability and effective transmembrane AA transporters (AATs). AA transport may be impaired in sedentary and older adults. We compared skeletal muscle AATs between young and older adults and examined effects of resistance training combined with increased protein intake. DESIGN: Secondary analysis from two randomized controlled trials SETTING: Participants were enrolled in trials comparing milk and native whey effects on anabolic signaling, muscle mass, and strength. PARTICIPANTS: Healthy young (n = 32; 14♀/18♂, 20-45 yrs) and older (n = 28; ♀/17♂, 70-80 yrs) adults INTERVENTION: Whole-body progressive resistance training 3×/week for 11-12 weeks with protein supplementation. MEASUREMENTS: Pre- and post-intervention assessments included lean leg mass (LLM), one-repetition maximum (1RM) leg press, and AAT protein levels in m. vastus lateralis biopsies. Western blots quantified L-Type Amino Acid Transporter 1 (LAT1) and 3 (LAT3), 4 F2 heavy chain (CD98) and solute carrier 38 member 9 (SNAT9) in cytosol (C), membrane (M) and nuclear (N) fractions. LAT1 membrane (IF-M) and intracellular (IF-IC) distribution were assessed by immunofluorescence. RESULTS: Training increased LLM by ∼1 kg and 1RM leg press by ∼31% in both groups (p < 0.001). At baseline, older adults showed higher SNAT9M and IF-M LAT1 and lower LAT1C versus young (p < 0.05). Training produced age-dependent changes: LAT3C increased in young (p = 0.39) and CD98M increased in old (p = 0.26) yielding significant time × age interactions (p < 0.05). Across groups, training reduced LAT1 intensity and SNAT9M and increased CD98N (p < 0.01-05). In young participants, IF-IC LAT1 decreased 9 ± 14% (p < 0.05) and CD98N increased 59 ± 97%(p < 0.01). Posttraining, older adults displayed higher IF-M LAT1 and lower CD98M than young (p < 0.05). CONCLUSION: Resistance training with protein supplementation improved muscle mass and strength and modified AAT profiles. Age was associated with higher membrane LAT1 and SNAT9, while training attenuated some age-related differences and produced distinct effects on LAT3 and CD98

Although protein supplementation is a common sports nutrition strategy, there is little research on its effects in adolescent athletes. Our objective was to assess the effects of whey protein supplementation on athletic performance and body composition in adolescent soccer players over a 10-week competitive soccer season. Adolescent athletes (n = 22; 59% female, age: 15.6 ± 0.2 [mean ± SEM] years; BMI percentile: 55.9 ± 6.2%) were randomized to consume either whey protein (PRO; n = 10; 20 g protein) or an isocaloric placebo (CON; n = 12) twice daily. Outcome measures included: estimated V̇O2max (1.5 mile run), sprint time (30 yard dash), muscle strength and endurance (quadricep isometric leg extension; maximum voluntary contraction and repetitions to fatigue, respectively), and body composition (fat mass and fat-free mass). Assessments were conducted at baseline and postintervention. V̇O2max improved in both groups (p < 0.001), with greater (p = 0.04) increases in the PRO versus CON group. Sprint time improved in both groups (p = 0.03), with no significant differences between groups. Muscle strength was similar across the study for both groups. Muscular endurance declined in the PRO group compared to CON (p = 0.01). Fat-free mass increased in both groups (p = 0.02), whereas fat mass was unchanged. Our results indicate that whey protein supplementation during the competitive season in adolescent athletes improved V̇O2max compared to control. However, whey protein did not lead to improvements in sprint performance, musculoskeletal fitness, and body composition compared to control. clinicaltrials.gov (NCT05589129).

BACKGROUND/OBJECTIVES: Whether saponins aid in whey protein supplementation remains unclear. We aimed to investigate the effects of Astragalus and Panax saponins (APS) on whey protein absorption, intestinal permeability, and muscle function in healthy adults across different age groups. METHODS: A randomized, double-blind, placebo-controlled crossover trial was conducted with 30 healthy participants equally stratified into three age groups (18-25, 26-59, and 60-80 years), over two phases: a single-dose trial to measure immediate amino acid absorption from whey protein and a 4-week phase combining daily supplementation with resistance training to assess long-term effects on amino acid absorption kinetics, muscle function, and gut health. RESULTS: Immediate APS supplementation resulted in a 6.67% higher area under the curve for valine, 3.62% for leucine, and 0.15% for isoleucine, compared with the placebo. After 4 weeks, APS supplementation significantly increased the absorption of valine (14.07%) and leucine (8.34%) and improved the absorption of isoleucine (6.33%). The effects were most pronounced in older adults (60-80 years), who showed a 12.74% increase in total essential amino acid absorption. APS also caused a substantially greater increase (APS: +5.20% vs. placebo: +2.44%) in grip strength, an increase (APS: +0.85% vs. placebo: +0.68%) in muscle mass, and a reduction in blood zonulin levels (APS: -13.01% vs. placebo: -0.9%), indicating improved muscle function and intestinal barrier integrity, without adverse effects on liver or kidney function. CONCLUSIONS: APS supplementation enhances amino acid absorption from whey proteins, muscle function and gut barrier integrity, especially in older adults. These findings highlight its synergistic role in improving protein supplementation efficacy for those with age-related muscle loss.

Background/Objectives: Metabolic dysfunction-associated steatotic liver disease (MASLD) often requires caloric restriction (CR) to reduce hepatic fat, but CR can compromise muscle mass and function. Resistance training and whey protein are anabolic stimuli, yet their independent and combined effects under substantial CR are unclear. Methods: In a 4-week randomized, double-blind trial, adults with MASLD (n = 45) under ~30% CR were allocated to four groups: resistance training with whey protein supplementation (E-PRO), resistance training with placebo (E-PLA), whey protein supplementation only (PRO), or placebo only (PLA). PRO groups consumed 1.5 g·kg-1·day-1 protein, while PLA groups consumed 0.8 g·kg-1·day-1. Exercise groups performed supervised exercise 5 days/week. Outcomes included body composition and isokinetic muscle function. Results: Across ~30% CR, all groups reduced body weight and fat mass without skeletal muscle mass loss; no between-group differences in body composition changes were observed. For peak torque, E-PRO improved across all regions except trunk, E-PLA improved except non-dominant shoulder flexors and trunk flexors, PRO improved non-dominant knee flexors and shoulder extensors, and PLA showed no change. For total work, E-PRO and E-PLA increased across all regions PRO improved dominant knee extensors/flexors and shoulder extensors; PLA increased only non-dominant knee extensors. E-PRO and E-PLA exceeded PLA for multiple knee/shoulder/trunk outcomes. Conclusions: In individuals with MASLD undergoing severe CR, ≥0.8 g·kg-1·day-1 of protein preserves skeletal muscle mass. However, the anabolic synergy of resistance training and protein for functional adaptation appears to be blunted by the substantial energy deficit.

Endurance athletes have an increased risk of bone stress injuries due to high training and energy demands. Endurance training with inadequate recovery triggers a pro-inflammatory response, which can upregulate bone resorption for hours to days. Combined dietary protein and carbohydrate supplementation post-exercise has shown to attenuate bone resorption and pro-inflammatory cytokine responses, though the effect of dietary protein intake alone remains to be elucidated. This randomized cross-over, double-blinded study examined the acute effects of post-exercise protein supplementation on serum concentrations of osteokine and inflammatory cytokines in endurance runners. Fourteen young male and female (n = 7 each) endurance runners with a weekly training distance ≥40 km were included. Participants underwent (i) a protein treatment (0.5 g/kg whey isolate), and (ii) a control/water treatment; consumed immediately after a treadmill run to volitional exhaustion at 70% maximal oxygen consumption. Blood samples were taken at baseline, 0, 1, 2, 3, 4, and 24 h post-exercise, and analyzed with immunosorbent and multiplex assays. A linear mixed model assessed the effects of time and treatment for each marker, and interactions (sex, sequence, period, and baseline difference as covariates). There were no significant treatment by time effects for any blood markers. There were significant main effects of time for serum sclerostin (p < 0.0001), dickkopf-1 (p < 0.0001), osteoprotegerin (p < 0.0001), and tumor necrosis factor-alpha (p = 0.004); these markers increased immediately post-exercise and returned to baseline by 24 h. Acute whey protein supplementation did not induce a different bone or inflammatory response following exhaustive running exercise in young endurance runners compared to the control. Registration number: NCT06645119.

Erratum in Int J Sport Nutr Exerc Metab. 2026 Jan 20;36(2):169. doi: 10.1123/ijsnem.2026-0006. The effects of Greek yogurt and whey protein supplementation on markers of bone turnover and inflammation were compared in university athletes over a competitive season. Participants (n = 32, 16 females) followed their habitual diets for an 8-week control period and were then randomly assigned to one of two trial arms: two servings per day of either 175 g of Greek yogurt (17 g protein) or isonitrogenous whey protein for a 16-week intervention period. Morning, fasting blood was collected at Weeks 0 (precontrol), 8 (postcontrol/preintervention), 16 (midintervention), and 24 (postintervention) and analyzed for osteocalcin, amino-terminal propeptide of Type I collagen, insulin-like growth factor 1, osteoprotegerin, C-telopeptides of Type I collagen, sclerostin, receptor activator of nuclear factor kappa-B ligand, tumor necrosis factor-alpha, interleukin 6, and interleukin 10. No main effects or interactions were found for markers of bone formation. In the Greek yogurt group, C-telopeptides of Type I collagen increased from pre- to postcontrol and returned to baseline concentrations postintervention while remaining stable throughout the study in whey protein (Time × Group interaction, p = .048). Receptor activator of nuclear factor kappa-B ligand increased from pre- to postcontrol (time effect, p = .014), returning to baseline by midintervention across groups. Males had higher sclerostin (sex effect, p = .021) and interleukin 10 (sex effect, p = .004) with no interactions. Interleukin 6 showed no main effects or interactions. Tumor necrosis factor-alpha increased pre- to postcontrol (time effect, p = .053) then decreased to baseline levels postintervention. Although protein supplementation, independent of source (wholefood or isolates), showed potential bone and inflammatory benefits during athletic training, it remains unclear whether these effects were solely attributable to the supplements.