Does sex matter in the cheetah? Insights into the skeletal muscle of the fastest land animal.

The cheetah is considered the fastest land animal, but studies on their skeletal muscle properties are scarce. Vastus lateralis biopsies, obtained from male and female cheetahs as well as humans, were analysed and compared for fibre type and size, and metabolism. Overall, cheetah muscle had predominantly type IIX fibres, which was confirmed by the myosin heavy chain isoform content (type I: 17±8%, type IIA: 21±6%, type IIX: 62±12%), whereas humans contained predominantly type I and IIA fibres (type I: 49±14%, type IIA: 43±8%, type IIX: 7±7%). Cheetahs had smaller fibres than humans, with larger fibres in the males compared to their female counterparts. Citrate synthase (16±6 vs. 28±7 µmol/min/g prot, P<0.05) and 3-hydroxyacetyl co-enzyme a dehydrogenase (30±11 vs. 47±15 µmol/min/g prot, P<0.05) activities were lower in cheetahs, whereas lactate dehydrogenase activity was 6 times higher in cheetahs (2159±827 vs. 382±161 µmol/min/g prot, P<0.001). The activities of creatine kinase (4765±1828 vs. 6485±1298, P<0.05 µmol/min/g prot) and phosphorylase (111±29 vs. 216±92 µmol/min/g prot) were higher in humans, irrespective of higher type IIX fibres in cheetahs. Superoxide dismutase and catalase, markers of antioxidant capacity, were higher in humans, but overall antioxidant capacity was higher in cheetahs. To conclude, fibre type, fibre size and metabolism differ between cheetahs and humans, with limited differences between the sexes.

Detailed description of multidisciplinary prehabilitation in patients admitted to nerve sparring radical prostatectomy - A randomized feasibility study protocol.

Background: Localized prostate cancer treated with radical prostatectomy is highly effective, though severe side-effects are common after the surgery. Prehabilitation is an approach to optimize patient's physical and mental resources before surgery, to improve postoperative outcomes. The feasibility of a multi-modal home-based prehabilitation program, delivered using telehealth in patients awaiting radical prostatectomy is unknown. This paper describes the development of a prehabilitation program for patients awaiting radical prostatectomy. Method: A model by The Medical Research Council for developing and evaluating complex interventions (MRC Framework) was used in the development process. The Template for Intervention Description and Replication (TIDieR) checklist was applied for ensuring sufficient description of the interventions. A total of 40 patients will be randomized to either intervention or control group. Patients in the control group will follow standard care. The 4-week prehabilitation programme consists of exercise, pelvic floor exercise, sexual counseling, stress management and nutritional support. The interventions are home-based and delivered using telehealth. Feasibility outcomes will include recruitment, attrition rates, adherence, safety and suitability. Conclusion: We have developed a multimodal prehabilitation programme, which has the potential to bring tangible health benefits to men with prostate cancer awaiting radical prostatectomy. The results of the feasibility study will inform the design of a fully powered randomized controlled trial.

A comparative analysis of fear of cancer recurrence in patients with small renal masses: Active surveillance versus cryoablation.

BACKGROUND AND PURPOSE: The aim of this study was to evaluate and compare the fear of cancer recurrence (FCR) in patients diagnosed with a small renal mass (SRM) and managed with either active surveillance (AS) or minimal invasive renal cryoablation (CA). PATIENTS/MATERIAL AND METHODS: A total of 398 patients with SRMs (263 AS and 135 CA patients) were retrospectively identified across three institutions and invited to complete the Fear of Cancer Recurrence-Short Form (FCRI-SF) questionnaire. RESULTS: No statistically significant differences in FCRI-SF score were observed between the AS (mean = 10.9, standard deviation [SD] = 6.9) and CA (mean = 10.2, SD = 7.2) (p = 0.559) patients, with the mean scores of both groups being below the suggested clinically significant cut-off of 16. A total of 25% of AS and 28% of CA patients reported sub-clinical or clinical levels of FCR (FCRI-SF score > 16). Within the AS group, a weak negative association between FCR severity and age was observed (r = -0.23, p = 0.006), and a statistically significant difference in FCRI-SF score between patients aged more or less than 73 years (p = 0.009). INTERPRETATION: FCR levels were comparable between AS and CA patients, suggesting that treatment decisions should prioritise clinical factors. Up to 28% of AS and CA patients report clinically significant FCR, highlighting the importance of considering the possibility of FCR, especially in younger patients.

Ureteroenteric strictures after cystectomy: Side-specific risk factors and radiological assessment.

Objective: To evaluate risk factors contributing to side-specific benign ureteroenteric strictures following radical cystectomy with an ileal conduit. Materials and Methods: Data obtained from patients with bladder cancer who underwent radical cystectomy with ileal conduit surgery between 2015 and 2018 were retrospectively analysed. Imaging prior to surgery was analysed, regarding calcifications in the aorta, sarcopenia and postoperatively for length of remaining left ureter. Descriptive analyses were performed on preoperative and perioperative data, comparing patients who developed unilateral left- or right-sided strictures, bilateral strictures, to those who remained free of strictures. COX regression analysis was employed to calculate crude and adjusted hazard ratio for side-specific strictures. Results: The study included 395 patients. Strictures developed in 19% (75/395) of the patients, within a median period of 9 months: 57% (43/75) unilateral left sided, 20% (15/75) unilateral right sided and 23% (17/75) bilateral. Unilateral left-sided stricture was associated with higher body mass index (p = 0.077) and hypercholesterolemia (p = 0.007). Right-sided stricture was associated with a history of prior abdominal surgery (p = 0.029) and postoperative leakage (p = 0.004). Bilateral stricture was associated with smoking (p = 0.006) and high BMI (p = 0.015). The adjusted HR comparing patients with and without previous abdominal surgery was only significantly higher for right-sided ureteroenteric strictures (HR 3.18 [95% CI: 1.11; 9.05]) compared with patients without strictures. No association was identified between strictures and preoperative aortic calcification of the abdominal aorta or sarcopenia as estimated from imaging. Conclusion: The aetiology of ureteroenteric strictures appears multifactorial. Our findings suggest that development of left-sided stricture is influenced by factors associated with metabolic syndrome, indicating a potential role of distal ureteric ischemia. On the other hand, right-sided stricture was more frequent in patients with previous abdominal surgery and postoperative leakage.

Super Resolution Ultrasound Imaging using the Erythrocytes: I: Density Images.

A new approach for vascular super resolution imaging using the erythrocytes as targets (SURE imaging) is described and investigated. SURE imaging does not require fragile contrast agent bubbles, making it possible to use the maximum allowable mechanical index for ultrasound scanning for an increased penetration depth. A synthetic aperture ultrasound sequence was employed with 12 virtual sources using a 10 MHz GE L8-18i-D linear array hockey stick probe. The axial resolution was 1.20λ,(185.0µm) and the lateral resolution was 1.50λ,(231.3µm). Field IIpro simulations were conducted on 12.5 µm radius vessel pairs with varying separations. A vessel pair with a separation of 70 µm could be resolved, indicating a SURE image resolution below half a wavelength. A Verasonics research scanner was used for the in vivo experiments to scan the kidneys of Sprague-Dawley rats for up to 46 s to visualize their microvasculature by processing from 0.1 up to 45 s of data for SURE imaging, and for 46.8 s for super resolution (SR) imaging with a SonoVue contrast agent. Afterward, the renal vasculature was filled with the ex vivo micro-CT contrast agent Microfil, excised, and scanned in a micro-CT scanner at both a 22.6 µm voxel size for 11 hours, and for 20 hours in a 5 µm voxel size for validating the SURE images. Comparing the SURE and micro-CT images revealed that vessels with a diameter of 28 µm, five times smaller than the ultrasound wavelength, could be detected, and the dense grid of microvessels in the full kidney was shown for scan times between 1 to 10 s. The vessel structure in the cortex was also similar for the SURE and SR images. Fourier ring correlation indicated a resolution capability of 29 µm. SURE images are acquired in seconds rather than minutes without any patient preparation or contrast injection, making the method translatable to clinical use.

Perioperative management of upper tract urothelial carcinoma in the Nordic countries.

BACKGROUND: Upper tract urothelial carcinoma (UTUC) is a rare malignancy, with typically only few new cases annually per urological department. Adherence to European association of urology (EAU) guidelines on UTUC in the Nordic countries is unknown. The objective of this survey was to examine the implementation of EAU guidelines, the perioperative management and organization of the treatment of UTUC in the Nordic countries. METHODS: The electronic survey was distributed to 93 hospitals in the Nordic countries performing radical nephroureterectomy (NU). The survey consisted of 57 main questions and data was collected between December 1st, 2021 and April 23rd, 2022. RESULTS: Overall response rate was 47/93 (67%) with a completion rate of 98%. Five out of the 6 examined subjects on diagnostic practice are applied by ≥ 72% of the participating centers. NU as treatment for high-risk UTUC is performed by 37/47 (79%), and 91% include a bladder cuff excision. CONCLUSIONS: Adherence to EAU guidelines is high on diagnostic practice in the Nordic countries, whereas disease management is less coherent.

Super Resolution Ultrasound Imaging Using the Erythrocytes: II: Velocity Images.

Super resolution ultrasound imaging using the erythrocytes (SURE) has recently been introduced. The method uses erythrocytes as targets instead of fragile microbubbles (MBs). The abundance of erythrocyte scatterers makes it possible to acquire SURE data in just a few seconds compared to several minutes in ultrasound localization microscopy (ULM) using MBs. A high number of scatterers can reduce the acquisition time, however, the tracking of uncorrelated and high-density scatterers is quite challenging. This paper hypothesizes that it is possible to detect and track erythrocytes as targets to obtain vascular flow images. A SURE tracking pipeline is used with modules for beamforming, recursive synthetic aperture imaging, motion estimation, echo canceling, peak detection, and recursive nearest neighbor tracker. The SURE tracking pipeline is capable of distinguishing the flow direction and separating tubes of a simulated Field II phantom with 125 to 25 µm wall-to-wall tube distances, as well as a 3D-printed hydrogel micro-flow phantom with 100 to 60 µm wall-to-wall channel distances. The comparison of an in-vivo SURE scan of a Sprague-Dawley rat kidney with ULM and micro-CT scans with voxel sizes of 26.5µm and 5µm demonstrated consistent findings. A microvascular structure composed of 16 vessels exhibited similarities across all imaging modalities. The flow direction and velocity profiles in the SURE scan were found to be concordant with those from ULM.

Underestimation of Flow Velocity in 2-D Super-Resolution Ultrasound Imaging.

Velocity estimation in ultrasound imaging is a technique to measure the speed and direction of blood flow. The flow velocity in small blood vessels, i.e., arterioles, venules, and capillaries, can be estimated using super-resolution ultrasound imaging (SRUS). However, the vessel width in SRUS is relatively small compared with the full-width-half-maximum of the ultrasound beam in the elevation direction (FWHMy), which directly impacts the velocity estimation. By taking into consideration the small vessel widths in SRUS, it is hypothesized that the velocity is underestimated in 2-D super-resolution ultrasound imaging when the vessel diameter is smaller than the FWHMy. A theoretical model is introduced to show that the velocity of a 3-D parabolic velocity profile is underestimated by up to 33% in 2-D SRUS, if the width of the vessel is smaller than the FWHMy. This model was tested using Field II simulations and 3-D printed micro-flow hydrogel phantom measurements. A Verasonics Vantage 256™ scanner and a GE L8-18i-D linear array transducer with FWHMy of approximately 770 µm at the elevation focus were used in the simulations and measurements. Simulations of different parabolic velocity profiles showed that the velocity underestimation was 36.8%±1.5% (mean±standard deviation). The measurements showed that the velocity was underestimated by 30%±6.9%. Moreover, the results of vessel diameters, ranging from 0.125×FWHMy to 3×FWHMy, indicate that velocities are estimated according to the theoretical model. The theoretical model can, therefore, be used for the compensation of velocity estimates under these circumstances.

Whole-genome Mutational Analysis for Tumor-informed Detection of Circulating Tumor DNA in Patients with Urothelial Carcinoma.

BACKGROUND AND OBJECTIVE: Circulating tumor DNA (ctDNA) can be used for sensitive detection of minimal residual disease (MRD). However, the probability of detecting ctDNA in settings of low tumor burden is limited by the number of mutations analyzed and the plasma volume available. We used a whole-genome sequencing (WGS) approach for ctDNA detection in patients with urothelial carcinoma. METHODS: We used a tumor-informed WGS approach for ctDNA-based detection of MRD and evaluation of treatment responses. We analyzed 916 longitudinally collected plasma samples from 112 patients with localized muscle-invasive bladder cancer who received neoadjuvant chemotherapy (NAC) before radical cystectomy. Recurrence-free survival (primary endpoint), overall survival, and ctDNA dynamics during NAC were assessed. KEY FINDINGS AND LIMITATIONS: We found that WGS-based ctDNA detection is prognostic for patient outcomes with a median lead time of 131 d over radiographic imaging. WGS-based ctDNA assessment after radical cystectomy identified recurrence with sensitivity of 91% and specificity of 92%. In addition, genomic characterization of post-treatment plasma samples with a high ctDNA level revealed acquisition of platinum therapy-associated mutational signatures and copy number variations not present in the primary tumors. The sequencing depth is a limitation for studying tumor evolution. CONCLUSIONS AND CLINICAL IMPLICATIONS: Our results support the use of WGS for ultrasensitive ctDNA detection and highlight the possibility of plasma-based tracking of tumor evolution. WGS-based ctDNA detection represents a promising option for clinical use owing to the low volume of plasma needed and the ease of performing WGS, eliminating the need for personalized assay design. PATIENT SUMMARY: Detection of tumor DNA in blood samples from patients with cancer of the urinary tract is associated with poorer outcomes. Disease recurrence after surgery can be identified by the presence of tumor DNA in blood before it can be detected on radiography scans.

Use of Bladder-Related Medication in Non-Muscle Invasive Bladder Cancer Patients.

Repeated transurethral bladder resections (TURBs) and instillation treatments in non-muscle invasive bladder cancer (NMIBC) might influence bladder function and, therefore, quality of life. Bladder-related medication is a surrogate marker of compromised bladder function. The objective was to investigate whether TURBs and adjuvant instillation therapy are associated with the use of anticholinergics, ß3-agonists, and cystitis-relevant antibiotics. We divided all Danish patients diagnosed with primary NMIBC during 2002-2017 registered in the Danish National Patient Registry (DNPR) based on TURB-load within the first five years from diagnosis (1 TURB, 2-4 TURBs, ≥5 TURBs). Instillation therapy with either mitomycin C (MMC) or bacillus Calmette-Guerin vaccine (BCG) was independent exposure (yes or no). We included 17,774 patients; 76% men, median age: 70 years (IQR: 63, 77). Patients exposed to ≥5 TURBs had a higher risk of using bladder-relaxing medication than patients exposed to 1 TURB, HR = 4.01 [3.33; 4.83], and higher risk of cystitis, HR = 2.27 [2.05; 2.51]. BCG-exposed patients had a higher risk of bladder-relaxing medication use compared to non-exposed, HR = 1.92 [1.69; 2.18], and a higher risk of cystitis, HR = 1.39 [1.31; 1.48]. Repeated TURBs have the highest impact on bladder function. Adjuvant instillation therapy is also associated with the use of bladder-related medication.

Patient-Reported Outcomes after Laser Ablation for Bladder Tumours Compared to Transurethral Resection-A Prospective Study.

The standard procedure for diagnosis and treatment of bladder tumours, transurethral resection of bladder tumour (TURBT), is associated with a complication rate of up to 26% and potentially has severe influence on patient-reported outcomes (PRO). Outpatient transurethral laser ablation (TULA) is an emerging new modality that is less invasive with a lower risk of complications and, thereby, possibly enhanced PRO. We collected PRO following transurethral procedures in treatment of bladder tumours to evaluate any clinically relevant differences in symptoms and side effects. This prospective observational study recruited consecutive patients undergoing different bladder tumour-related transurethral procedures. Patients filled out questionnaires regarding urinary symptoms (ICIQ-LUTS), postoperative side effects, and quality of life (EQ-5D-3L) at days 1 and 14 postoperatively. In total, 108 patients participated. The most frequently reported outcomes were postoperative haematuria and pain. Patients undergoing TURBT reported longer lasting haematuria, a higher perception of pain, and a more negative impact on quality of life compared to patients undergoing TULA. TURBT-treated patients had more cases of acute urinary retention and a higher need for contacting the healthcare system. Side effects following transurethral procedures were common but generally not severe. The early symptom burden following TURBT was more extensive than that following TULA.

Active Surveillance of Small Renal Masses in a Large Danish Cohort: Assessing Proficiency in Patient Selection.

Small renal masses (SRMs) are often benign or early-stage cancers with low metastatic potential. The risk of overtreating SRMs is a particular concern in elderly or comorbid patients, for whom the risks associated with active surveillance (AS) are lower than the risks of surgical management. The aim is to systematically analyse a large cohort of AS patients to provide valuable insights into patient selection and outcomes concerning delayed intervention (DI) and AS termination. We retrospectively analysed data from 563 AS patients across three institutions from 2012 to 2023. Patients were classified into three groups: those currently in AS (n=283), those who underwent DI (n=75), and those who terminated AS (n=205). DI patients were younger, and had larger initial tumour size and higher growth rates (GRs) than AS patients. A significant number of patients terminated their AS, mainly due to comorbidities and death from non-kidney cancer causes, suggesting unsuitability for initial AS enrolment. AS appears to be a safe initial management strategy for SRMs, with an overall low GR and only one patient developing metastasis. The patient selection for AS appears inconsistent, highlighting the need for improved criteria to identify AS candidates, especially considering comorbidities and the possibility of subsequent active treatment in the event of progression.

Consumer preferences for attributes in sweet beverages and market impacts of beverage innovation.

Consumption of sugar-sweetened beverages (SSB) is considered as an important risk factor for the development of overweight and obesity in populations worldwide, with a particular focus on the risks in the younger parts of the population - children and adolescents. Together with fiscal measures and information tools, innovation-based approaches such as the development of sugar-free or sugar-reduced versions of established beverages and development of new beverage products have been used to reduce this challenge, but the effects of product innovation on sugar intake are not well understood from the literature, as previous studies have largely ignored substitution effects of product innovation in the beverage domain. The objective of the present study was to investigate the potential effectiveness of product innovation as a strategy to affect consumers' intake of energy from sweetened non-alcoholic beverages. Using household panel shopping data from approximately 3000 Danish households over the years 2006-2014, we developed a hedonic pricing approach to estimate the influence of product attributes on consumers' utility, based on observed data for Danish households' purchases of sweet drinks. Overall, the study found that beverages' degree of sweetness positively affected the satiation effect of beverage consumption and in turn made the demand for these beverages less sensitive to e.g. price changes or introduction of competing products, whereas the energy density of the beverages positively affected the demand sensitivity to market changes. Findings like these can be useful for assessing market effects as well as environmental and public health impacts of changes to the market environment.

ULTRA-SR Challenge: Assessment of Ultrasound Localization and TRacking Algorithms for Super-Resolution Imaging.

With the widespread interest and uptake of super-resolution ultrasound (SRUS) through localization and tracking of microbubbles, also known as ultrasound localization microscopy (ULM), many localization and tracking algorithms have been developed. ULM can image many centimeters into tissue in-vivo and track microvascular flow non-invasively with sub-diffraction resolution. In a significant community effort, we organized a challenge, Ultrasound Localization and TRacking Algorithms for Super-Resolution (ULTRA-SR). The aims of this paper are threefold: to describe the challenge organization, data generation, and winning algorithms; to present the metrics and methods for evaluating challenge entrants; and to report results and findings of the evaluation. Realistic ultrasound datasets containing microvascular flow for different clinical ultrasound frequencies were simulated, using vascular flow physics, acoustic field simulation and nonlinear bubble dynamics simulation. Based on these datasets, 38 submissions from 24 research groups were evaluated against ground truth using an evaluation framework with six metrics, three for localization and three for tracking. In-vivo mouse brain and human lymph node data were also provided, and performance assessed by an expert panel. Winning algorithms are described and discussed. The publicly available data with ground truth and the defined metrics for both localization and tracking present a valuable resource for researchers to benchmark algorithms and software, identify optimized methods/software for their data, and provide insight into the current limits of the field. In conclusion, Ultra-SR challenge has provided benchmarking data and tools as well as direct comparison and insights for a number of the state-of-the art localization and tracking algorithms.

Corrigendum: Effect of five hours of mixed exercise on urinary nitrogen excretion in healthy moderate-to-well-trained young adults.

[This corrects the article DOI: 10.3389/fnut.2024.1345922.].

Exploring the tumor genomic landscape of aggressive prostate cancer by whole-genome sequencing of tissue or liquid biopsies.

Treatment resistance remains a major issue in aggressive prostate cancer (PC), and novel genomic biomarkers may guide better treatment selection. Circulating tumor DNA (ctDNA) can provide minimally invasive information about tumor genomes, but the genomic landscape of aggressive PC based on whole-genome sequencing (WGS) of ctDNA remains incompletely characterized. Thus, we here performed WGS of tumor tissue (n = 31) or plasma ctDNA (n = 10) from a total of 41 aggressive PC patients, including 11 hormone-naïve, 15 hormone-sensitive, and 15 castration-resistant patients. Across all variant types, we found progressively more altered tumor genomic profiles in later stages of aggressive PC. The potential driver genes most frequently affected by single-nucleotide variants or insertions/deletions included the known PC-related genes TP53, CDK12, and PTEN and the novel genes COL13A1, KCNH3, and SENP3. Etiologically, aggressive PC was associated with age-related and DNA repair-related mutational signatures. Copy number variants most frequently affected 14q11.2 and 8p21.2, where no well-recognized PC-related genes are located, and also frequently affected regions near the known PC-related genes MYC, AR, TP53, PTEN, and BRCA1. Structural variants most frequently involved not only the known PC-related genes TMPRSS2 and ERG but also the less extensively studied gene in this context, PTPRD. Finally, clinically actionable variants were detected throughout all stages of aggressive PC and in both plasma and tissue samples, emphasizing the potential clinical applicability of WGS of minimally invasive plasma samples. Overall, our study highlights the feasibility of using liquid biopsies for comprehensive genomic characterization as an alternative to tissue biopsies in advanced/aggressive PC.

Definition of Benign Ureteroenteric Anastomotic Strictures in Ileal Conduits After Radical Cystectomy: Experience From a Single Center and Previously Published Literature.

OBJECTIVE: To evaluate a cohort of patients diagnosed with benign ureteroenteric stricture (UES) after radical cystectomy with ileal conduits using a strict predefined definition of strictures. Additionally, we want to illustrate the UES debut, regarding symptoms and clinical findings. UES is a well-known long-term complication after radical cystectomy, affecting up to 20% of all patients. In the literature, different incidence rates are reported. However, these are based on various definitions of strictures. METHODS: We used strict predefined criteria to evaluate UES incidence including symptoms, timing, diagnostic methods, treatment, and outcome in all patients who underwent radical cystectomy with an ileal conduit between 2012 and 2018 at a single high-volume center. RESULTS: Of a total of 693 patients who underwent radical cystectomy with ileal conduit, we found 109 patients with 135 UES in total, corresponding to 15.7% of patients (CI: 13.2-18.6) and 10% of all included ureteroenteric anastomosis (CI: 8.5-11.6) after radical cystectomy. Median follow-up was 24months (interquartile range (IQR): 12-31), and postoperatively UES was diagnosed after a median of 6months (IQR: 3-16). A total of 56% was diagnosed with elevated creatinine. Every UES underwent a median of two (IQR: 1-2) treatment attempts and 122 UES were treated successfully. CONCLUSION: Benign UES is a significant cause of morbidity following radical cystectomy. Our findings contribute to the knowledge of timing, incidence, and recommended treatment of strictures. We argue the importance of establishing a clear gold standard when defining UES to ensure accurate reporting in future research.

Antimicrobial treatment and resistance in sexually transmitted bacterial infections.

Sexually transmitted infections (STIs) have been part of human life since ancient times, and their symptoms affect quality of life, and sequelae are common. Socioeconomic and behavioural trends affect the prevalence of STIs, but the discovery of antimicrobials gave hope for treatment, control of the spread of infection and lower rates of sequelae. This has to some extent been achieved, but increasing antimicrobial resistance and increasing transmission in high-risk sexual networks threaten this progress. For Neisseria gonorrhoeae, the only remaining first-line treatment (with ceftriaxone) is at risk of becoming ineffective, and for Mycoplasma genitalium, for which fewer alternative antimicrobial classes are available, incurable infections have already been reported. For Chlamydia trachomatis, in vitro resistance to first-line tetracyclines and macrolides has never been confirmed despite decades of treatment of this highly prevalent STI. Similarly, Treponema pallidum, the cause of syphilis, has remained susceptible to first-line penicillin.

Effect of five hours of mixed exercise on urinary nitrogen excretion in healthy moderate-to-well-trained young adults.

Introduction: Carbohydrates and fats are the primary energy substrates during exercise, but proteins can also contribute. When proteins are degraded in the body, the amino groups are mainly converted to urea and excreted. Therefore, nitrogen excretion has been used as a marker of protein degradation, but a clear conclusion has yet to be reached on the effect of exercise on nitrogen excretion. Thus, we tested whether exercise increases nitrogen excretion. Methods: Fifteen young, healthy, moderate-to-well-trained participants (4 females, 11 males, VO2max 54.4 ± 1.7 mL·kg-1·min-1; mean ± SEM) participated in a randomized, balanced cross-over design investigation consisting of 1 day with 5 h of exercise (exercise day, EX) and 1 day with no exercise (control day, CON). The participants recorded their dietary intake the day before from 16:00 and throughout the intervention day. They then repeated these dietary intakes on the second trial day. A standardized lunch was provided on both days. In addition, participants were allowed to consume almost protein-free snacks in EX to ensure the same energy balance during both trial days. Urine was collected throughout the whole testing period, and urinary 3-methylhistidine (3-MH) excretion was measured to examine muscular catabolism. The sweat rate was calculated during the exercise period. Results and discussion: The urinary nitrogen and 3-MH excretions did not differ significantly between EX and CON (p = 0.764 and p = 0.953). The sweat rate was 2.55 ± 0.25 L in EX and 0.14 ± 0.15 L in CON (p < 0.001), and by estimating sweat nitrogen excretion, total nitrogen excretion was shown to differ with exercise. Our results showed that 5 hours of mixed exercise did not significantly impact urinary nitrogen and 3-MH excretions in healthy moderate-to-well-trained young adults.