Abstract Aims To compare the effects of high-intensity interval training (HIIT) alone versus HIIT-plus-resistance exercise training (ReHIIT) on multiple indices of physical function when delivered as surgical prehabilitation for colorectal cancer (CRC) patients scheduled for surgery with curative intent. Methods CRC patients scheduled for curative resection were recruited into a single-centre randomised trial. Participants were allocated to either HIIT or ReHIIT for a period of up to 31-days during the window between decision-to-treat and surgery. Functional assessments were conducted at baseline, prior to surgery, and 6-weeks post-operatively. Outcomes included handgrip strength (HGS), 6-minute walk test (6MWT) distance, timed up-and-go (TUG) time, short physical performance battery (SPPB) performance, and lower-limb strength. Data was analysed via 2-way ANOVA (group x time) with significance accepted as p<0.05. Results Forty participants were recruited. Only ReHIIT was able to elicit a significant improvement in lower-limb strength and was also able to prevent declines in strength after surgery. No significant change in any other outcome was observed during the prehabilitation or recovery period in either group. Conclusions Neither HIIT nor ReHIIT prehabilitation elicited improvements in clinically utilised measures of physical function. The improvements in lower-limb strength seen in those who completed ReHIIT does not appear to be reflected in these measures. It should be considered that both forms of prehabilitation may have mitigated post-surgery declines in physical function which cannot be seen in the absence of a control group, and that other key measures of physical function (i.e., cardiorespiratory fitness) may be improved by these interventions.

CONTEXT:Insulin resistance (IR) contributes to the pathogenesis of type 2 diabetes mellitus and is a risk factor for cardiovascular and neurodegenerative diseases. Amino acid and lipid metabolomic biomarkers associate with future type 2 diabetes mellitus risk in several epidemiological cohorts. Whether these biomarkers can accurately monitor changes in IR status following treatment is unclear. OBJECTIVE:Herein we evaluated the performance of clinical and metabolomic biomarker models to forecast altered IR, following lifestyle-based interventions. DESIGN:We contrasted the performance of two distinct insulin assay types (high-sensitivity ELISA and immunoassay) and built IR diagnostic models using cross-sectional clinical and metabolomic data. These models were used to stratify IR status in preintervention fasting samples, from 3 independent cohorts (META-PREDICT (n = 179), STRRIDE-AT/RT (n = 116), and STRRIDE-PD (n = 149)). Linear and Bayesian projective prediction strategies were used to evaluate models for fasting insulin and homeostatic model assessment 2 for insulin resistance and change in fasting insulin with treatment. RESULTS:Both insulin assays accurately quantified international standard insulin (R2 > 0.99), yet agreement between fasting insulins was less congruent (R2 = 0.65). A mean treatment effect on fasting insulin was only detectable using the ELISA. Clinical-metabolomic models were statistically related to fasting insulin (R2 0.33-0.39) but with modest capacity to classify IR at a clinically relevant homeostatic model assessment 2 for insulin resistance threshold. Furthermore, no model predicted treatment responses in any cohort. CONCLUSION:We demonstrate that the choice of insulin assay is critical when quantifying the influence of treatment on fasting insulin, whereas none of the clinical-metabolomic biomarkers, identified in cross-sectional studies, are suitable for monitoring longitudinally changes in IR status.

Background:Post-viral issues following acute infection with coronavirus disease 2019 (COVID-19), referred to widely as long COVID, are associated with episodic, persistent, and disabling symptoms affecting quality of life and functional status. Evidence demonstrates a significant impairment and long disease course, but there remains limited empirical data to profile and determine the fluctuating symptom profile of long COVID. Methods:We devised a 16-week, multicentre prospective cohort observation study to profile changes in patient-reported outcomes, and biological, physiological, psychological, and cognitive parameters following diagnosis and/or referral to an established long COVID clinic. Following baseline assessments, participants completed four face-to-face visits interspersed with telephone consultations. Face-to-face visits included physiological assessment, patient-reported outcome measures (PROMs), functional status, and respiratory function. Telephone consultations involved PROMs and symptom profiling. Results:Patient-reported outcomes improved from baseline to week sixteen, but demonstrated between visit fluctuations in frequency and severity. Further findings highlight the severity and frequency of long COVID symptom profiles and the extent of quality of life and functional status impairment. Conclusions:The data presented here highlight the episodic and relapsing nature and should be used to help characterise long COVID disability. They can inform the development of long COVID-specific guidelines and support services that can adequately respond to the reductions in patient well-being.

Renal perfusion, the delivery of oxygenated blood to kidney tissues, is important in the pathophysiology of acute and chronic kidney diseases. Despite this, accessible methods do not exist in clinical practice to measure renal perfusion or monitor the response to interventions in real time. Contrast-enhanced ultrasound (CEUS) is an emerging technique which uses a microbubble contrast agent which allows for continuous imaging of the vasculature and blood flow. The expected values for perfusion parameters of CEUS in healthy individuals and chronic kidney disease are not currently known. We conducted a prospective, observational study that recruited three groups of participants. Group 1 was comprised of healthy volunteers ≤40 years old, group 2 were healthy volunteers aged ≥70 years, and group 3 were people with CKD (eGFR 15–45 ml/min/1.73 m2). CEUS was performed using a Philips EPIQ ELITE ultrasound machine and an intravenous infusion of SonoVue® (Bracco) contrast. After achieving systemic steady-state of contrast, five destruction-reperfusion sequences were recorded for each participant, and videoclips were analysed using VueBox software. A time-intensity curve was generated from which mean transit time (mTT), the time taken to reach 50% maximal intensity, was derived. The median mTT across destruction-reperfusion sequences was used to generate a single mTT value per participant that were compared between the three groups using one-way ANOVA. For this analysis, 37 participants (10 healthy volunteers ≤40 years, 10 healthy volunteers ≥70 years and 7 patients with CKD) were included. Mean age was 30.5 ± 4.8 years in young healthy volunteers, 75.7 ± 3.0 years in older healthy volunteers, and 70.7 ± 4.2 years in the CKD group. Median eGFR was 110.0 [IQR 85.5–118.8] ml/min/1.73 m2 in the young volunteers, 85.5 [IQR 75.5–89.3] ml/min/1.73 m2 in the older volunteers, and 31.0 [IQR 26.0–38.0] ml/min/1.73 m2 in the CKD cohort. Cause of CKD was diabetic nephropathy in 3 participants, IgA nephropathy in 3 participants and tubulointerstitial nephritis in 1 participant. Mean mTT was significantly slower in individuals with CKD (3.6 ± 1.4 seconds) compared to both older (2.3 ± 0.6 seconds, P = 0.01) and young (1.8 ± 0.3 seconds, P < 0.001) healthy volunteers (Fig. 1). The difference between young and older volunteers was not significant (P = 0.4). The CKD group also displayed much greater dispersion of the mTT values (range: 2.1–4.7 seconds), compared with older (2.0–2.5) and younger (1.6–2.0) volunteers. CEUS is able to detect a difference in kidney cortical perfusion between healthy kidneys and those with CKD. These changes are distinct from age-related changes in perfusion. The higher degree of variability in the CKD cohort suggests greater heterogeneity between patients in the degree to which reductions in perfusion are associated with lower kidney function.

Resistance exercise (RE) enhances functionality in older adults and has proven effective as a means of cross-education in scenarios of unilateral disuse. However, the extent to which older adults demonstrate cross-limb transfer at the motor unit (MU) level following a single bout of unilateral RE is unclear. Thirteen healthy older adults (74.9 ± 4.8 years; 5 females) underwent bilateral neuromuscular assessments pre- and post- a single bout of unilateral RE consisting of sets of 12 repetitions of leg extension of the dominant (exercise) leg, at 75% of 1 repetition maximum, performed to failure. Maximum voluntary contraction (MVC) and force steadiness (FS) were measured. Central and peripheral features of individual MU were recorded using high-density surface electromyography and intramuscular electromyography (HDs/iEMG), during contractions normalised to 25% MVC. Following unilateral RE, MVC reduced in exercise (-14.8%, p < 0.001) and control (-6.9%, p = 0.003) legs, with reduced FS performance in the exercise leg compared to the control (p = 0.002). MU firing rate increased during contractions normalised to 25% baseline MVC in the exercised leg (p < 0.05), with no adaptation in the control leg (p > 0.05). All iEMG recorded measures of MU potentials remained unchanged in both legs (all p > 0.05). Acute unilateral RE leads to bilateral MVC reduction in older males and females, demonstrating the cross-limb transfer effect. However, adaptation of MU features was only apparent in the exercised limb, and mechanisms underlying the force decline in the non-exercised limb remain uncertain.

Cardiorespiratory fitness (CRF) and skeletal muscle mass (SMM) are both key parameters of intrinsic capacity. To date, the impact of adherence to physical activity guidelines by older adults on these facets is poorly understood. Therefore, this study aimed to assess the impact of 4 weeks adherence to UK physical activity guidelines on parameters of intrinsic capacity in older adults, with a secondary aim to determine the utility of a bedside-suitable predictive model of assessing CRF for predicting change in this parameter.

Background: owing to altered protein metabolism during critical illness, skeletal muscles are utilised as a source of protein, with subsequent debilitating effects on both muscle structure and function. Protein nutrition has been shown to improve clinical outcomes in critically unwell patients; however, the impact on muscle function is less established. Therefore, the aim of this review was to systematically determine the effect of protein dose on skeletal muscle strength in critically ill patients. Methods: we searched five databases (Ovid MEDLINE, Embase, Emcare, CINAHL, and PubMed) and clinical trial registers for randomised controlled trials (RCTs) of non-pregnant, adult patients admitted to an intensive care unit (ICU), which assessed the impact of different doses of protein nutrition on muscle strength. Studies investigating only muscle structure or with co-interventions were excluded. Six RCTs were eligible for inclusion, and five were suitable for meta-analysis. Results: there was a significant difference in skeletal muscle strength with higher versus lower protein intakes, with a mean difference of 2.36 kg (95% CI: 0.37–4.35). The mean difference in protein dose was 0.46 g/kg/d (95% CI: 0.29–0.64). Inconsistency was evident across the included studies, with risk of bias ranging from moderate to high. Conclusion: muscle strength of ICU patients does appear to be affected by different protein doses. However, trials focusing on muscle function are limited by number and quality, highlighting a clear need for future work.

Objectives: The impact of combining animal and plant protein sources on digestibility is unclear, despite their increasing clinical use. Using a non-invasive dual stable isotope tracer approach, we assessed the digestibility, bioavailability and utilization of distinct protein blends in older adults, and associated plasma amino acid profiles and muscle protein synthesis (MPS) rates. Methods: Thirty-two older men (69 ± 3 y) consumed one of four protein blends (A (51:49, casein/soy); B and C (35:25:20:20, whey/casein/soy/pea); D (80:20, casein/whey)) alongside primed constant infusions of [1,2-13C2] leucine for 8 h. Arterialized blood and vastus lateralis muscle biopsies were collected during a trickle feed protocol with all blends providing 20 g total protein, universally labeled 13C-spirulina, and 2H-cell free amino acid mix to determine digestibility. This trial was registered at Clinicaltrials.gov (ID-NCT07038655). Results: No differences (13C:2H ratios) were found in digestibility between the protein blends (p > 0.05). Mean (±SEM) fed state MPS at 2.5 h was 0.078 ± 0.009%/h, 0.075 ± 0.012%/h, 0.085 ± 0.007%/h and 0.065 ± 0.011%/h for drinks A, B, C and D, respectively, with a main time effect observed (p < 0.01), but no significant differences between drinks. Plasma essential amino acids (EAAs) increased significantly from baseline for all blends by 40 min (p < 0.05), with no differences between blends at any time point. Conclusions: These findings suggest that protein quantity (and/or leucine content), rather than composition, appears to be the most important factor driving MPS. Future work should focus on clinical populations where protein requirements and digestibility characteristics may differ.

AbstractBackgroundSkeletal muscle is a highly plastic tissue crucial for many functions associated with whole‐body health across the life course. Magnetic resonance imaging (MRI) is the current gold standard for measuring skeletal muscle size. However, MRI is expensive, and access to facilities is often limited. B‐mode ultrasonography (U/S) has been proposed as a potential alternative to MRI for the assessment of muscle size. However, to date, no work has explored the utility of U/S to assess disuse muscle atrophy (DMA) across muscles with different atrophy susceptibility profiles, an omission which may limit the clinical application of previous work.MethodsTo address this significant knowledge gap, 10 young men (22 ± years, 24.1 ± 2.3 kg/m2) underwent 15‐day unilateral leg immobilization using a knee‐brace and air boot. Cross‐sectional area (CSA) and muscle thickness (MT) of the tibialis anterior (TA) and medial gastrocnemius (MG) were assessed via U/S before and after immobilization, with CSA and muscle volume assessed via MRI.ResultsWith both muscles combined, there were good correlations between each U/S and MRI measure, both before (e.g., CSAMRI vs. MTU/S and CSAU/S: r = 0.88 and 0.94, respectively, both P < 0.0001) and after (e.g., VOLMRI vs. MTU/S and CSAU/S: r = 0.90 and 0.96, respectively, both P < 0.0001) immobilization. The relationship between the methods was notably stronger for MG than TA at each time‐point (e.g., CSAMRI vs. MTU/S: MG, r = 0.70, P = 0.0006; TA, r = 0.37, P = 0.10). There was no relationship between the degree of DMA determined by the two methods in either muscle (e.g., TA pre‐ vs. post‐immobilization, VOLMRI: 136 ± 6 vs. 133 ± 5, P = 0.08; CSAU/S: 6.05 ± 0.3 vs. 5.92 ± 0.4, P = 0.70; relationship between methods: r = 0.12, P = 0.75).ConclusionsBoth MTU/S and CSAU/S provide comparable static measures of lower leg muscle size compared with MRI, albeit with weaker agreement in TA compared to MG. Although both MTU/S and CSAU/S can discern differences in DMA susceptibility between muscles, neither can reliably assess degree of DMA. Based on the growing recognition of heterogeneous atrophy profiles between muscles, and the topical importance of less commonly studied muscles (i.e., TA for falls prevention in older adults), future research should aim to optimize accessible methods to determine muscle losses across the body.

Although muscle atrophy may partially account for age-related strength decline, it is further influenced by alterations of neural input to muscle. Persistent inward currents (PIC) and the level of common synaptic inputs to motoneurons influence neuromuscular function. However, these have not yet been described in the aged human quadriceps. High-density surface electromyography (HDsEMG) signals were collected from the vastus lateralis of 15 young (mean ± SD, 23 ± 5 y) and 15 older (67 ± 9 y) men during submaximal sustained and 20-s ramped contractions. HDsEMG signals were decomposed to identify individual motor unit discharges, from which PIC amplitude and intramuscular coherence were estimated. Older participants produced significantly lower knee extensor torque ( p < 0.001) and poorer force tracking ability ( p < 0.001) than young. Older participants also had lower PIC amplitude ( p = 0.001) and coherence estimates in the alpha frequency band ( p < 0.001) during ramp contractions when compared to young. Persistent inward currents and common synaptic inputs are lower in the vastus lateralis of older males when compared to young. These data highlight altered neural input to the clinically and functionally important quadriceps, further underpinning age-related loss of function which may occur independently of the loss of muscle mass.

Background & aims: Very-low calorie diets (VLCD) and the glucagon-like peptide-1 receptor agonist (GLP1RA) Semaglutide induce significant weight loss and improve glycaemic control in individuals with type 2 diabetes (T2D). This pilot study was conducted to explore the comparative short-term effects of these interventions individually, and in combination, on weight, body composition and metabolic outcomes. Methods: Thirty individuals with T2D (age 18-75 years, BMI 27-50 kg m-2)-2 ) were randomly assigned to receive Semaglutide (SEM), 800 kilocalorie/day VLCD (VLCD), or both in combination (COMB) for 12 weeks. Measurement of weight and glycated haemoglobin (HbA1c), dual energy X-ray absorptiometry, and intravenous glucose tolerance tests (IVGTT) were performed at baseline and post-intervention. Diet diaries were utilised to assess compliance. Insulin first phase response during IVGTT provided a marker of pancreatic beta-cell function, and insulin sensitivity was estimated using HOMA-IR. Results: Significantly greater reductions in body weight and fat mass were observed in VLCD and COMB, than SEM (p <0.01 v both). VLCD and COMB resulted in a 5.4 and 7 percentage-point greater weight loss than SEM, respectively. HbA1c and fasting glucose reduced significantly in all groups, however fasting insulin and HOMA-IR improved in VLCD and COMB only. Insulin first phase response during IVGTT increased in SEM and COMB, and this increase was significantly greater in COMB than VLCD (p < 0.01). Conclusion: VLCD elicited greater short-term losses of weight and fat mass than Semaglutide. Adding VLCD to Semaglutide stimulated further weight loss than Semaglutide alone. The combination did not yield any additive effects on weight and body composition above VLCD alone, but did provoke greater improvements in pancreatic beta-cell function. Thus, combination of Semaglutide and VLCD warrants further exploration as a novel approach to T2D management. (c) 2024 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

To investigate the effect of pre-operative exercise training on post-operative cognition. There are very few studies examining the effect of pre-operative exercise training on post-operative cognition. However, based on the results of previous studies, pre-operative exercise may increase post-operative cognition. More studies are needed to demonstrate the effect of pre-operative exercise training more clearly on post-operative cognition. Preoperative exercise training is a practice that may be effective on post-operative cognition, and studies are needed to examine its effect on older adults. With population aging and advances in surgical and anesthetic procedures, the incidence of surgery in patients over the age of 65 years is increasing. One post-operative complication often encountered by older surgical patients is post-operative cognitive dysfunction (POCD). Preoperative exercise training can improve the overall physiological resilience of older surgical patients, yet its impact on post-operative cognition is less well-established. Six databases (Medline (OVID); EMBASE (OVID); EMCARE (OVID); CINAHL (EBSCOHost), the Cochrane Library, and PubMed) were searched for studies reporting the effect of pre-operative physical training on post-operative cognition. The quality of evidence was assessed using the Mixed Methods Assessment Tool. A total of 3983 studies were initially identified, three of which met the inclusion criteria for this review. Two studies were pilot randomized trials, and one was a prospective randomized trial. Two of the studies were high-quality. Each study used a different type of physical exercise and cognition assessment tool. Across the studies, post-operative cognition (p = 0.005) and attention (p = 0.04) were found to be better in the intervention groups compared to control, with one study reporting no difference between the groups. Preoperative physical training may improve post-operative cognitive function, although more research with a consistent endpoint is required. Future studies should focus on patients at high risk of POCD, such as older adults, and explore the impact of different exercise regimes, including frequency, intensity, time, and type.

Introduction: Post-acute COVID-19 or Long COVID (LC) is a threat to health and well-being, and 1 in 10 infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) will develop persistent symptoms. LC is associated with >200 symptoms that impact quality of life and functional status. Many LC patients are being dismissed from care due to returning ‘normal’ results on ‘routine’ clinical investigations. Accordingly, the objective of the study was to explore the relationship between potential diagnostic biomarkers, symptom profile severity and functional status. Method: Participants with a confirmed history of COVID-19 were recruited from Long COVID clinics in the United Kingdom, as part of a 16-week cohort observation study. Venous blood samples were taken from 35 individuals [24 female] and assessed for standard clinical chemistry markers of inflammatory and metabolic status, including full blood count (white blood cells [WBC], red blood cells [RBC], platelets, haemoglobin, hematocrit, ferritin, mean corpuscular volume [MCV] mean corpuscular haemoglobin [MCH], mean corpuscular haemoglobin concentration [MCHC], red cell distribution width [RDW], basophils, neutrophils, lymphocytes, eosinophils, monocytes), CRP, d dimers, interleukin 6 (IL-6), and lactate dehydrogenase [LDH]. Patient-reported outcomes and symptoms were assessed by validated self-report methods including fatigue, dyspnoea, cognitive deficit, quality of life and symptom frequency and severity. Functional status was assessed via 6-Minute-Walk (6MWT). Results: Sixty-three percent of participants [17 female] had one or more values outside of expected reference ranges (WBC n=3, RBC n=6, haemoglobin n=3, haematocrit n=2, MCV n=3, MCH n=3, MCHC n= 1, RDW n=4, neutrophils n=3, lymphocytes n=5, monocytes n=1, basophils n=2, CRP n=3, ferritin n=3, d-dimer n=9). These changes were not linked to changes in function status or patient-reported outcomes ( p=>0.05), but there was a significant between-group difference with those outside of expected reference ranges completing less on the 6MWT on their final visit ( p=<0.05). Discussion: The pathophysiology of LC is complex and patients report broad symptoms across multiple organ systems, such as respiratory, gastrointestinal, cardiovascular, and the autonomic nervous system. Routine clinical investigations of biomarkers are vital, but assessments often return results within a pre-determined ‘normal’ range. Whilst routine testing is important, condition-specific investigations should also be explored. Further inspection of the data in reference to the symptom profile and reduced functional status demonstrates a need for more holistic approaches. Conclusion: The complex pathophysiology of LC requires further understanding and development of investigative approaches to LC diagnoses and treatment. Routine investigations of people with LC demonstrate abnormal responses, and even those that return ‘normal’ results experience debilitating symptom profiles and reduced quality of life. Due to the complex underlying mechanistic issues of LC, more specific biochemical profiling is required during clinical investigations. This study was supported by an unrestricted investigator-sponsored research grant from Gilead Sciences (#IN-UK-983-6080). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Parkinson’s disease (PD) is a neurodegenerative disorder with increasing prevalence into older age. Aerobic exercise (AE) is the most commonly prescribed exercise for PD, although an optimal protocol is undefined. This umbrella review aimed to summarise and synthesize existent evidence regarding the effectiveness of AE on balance, gait, functional mobility, and QoL in people with PD.

As a result of advances in medical treatments and associated policy over the last century, life expectancy has risen substantially and continues to increase globally. However, the disconnect between lifespan and 'health span' (the length of time spent in a healthy, disease-free state) has also increased, with skeletal muscle being a substantial contributor to this. Biological ageing is accompanied by declines in both skeletal muscle mass and function, termed sarcopenia. The mechanisms underpinning sarcopenia are multifactorial and are known to include marked alterations in muscle protein turnover and adaptations to the neural input to muscle. However, to date, the relative contribution of each factor remains largely unexplored. Specifically, muscle protein synthetic responses to key anabolic stimuli are blunted with advancing age, whilst alterations to neural components, spanning from the motor cortex and motoneuron excitability to the neuromuscular junction, may explain the greater magnitude of function losses when compared with mass. The consequences of these losses can be devastating for individuals, their support networks, and healthcare services; with clear detrimental impacts on both clinical (e.g., mortality, frailty, and post-treatment complications) and societal (e.g., independence maintenance) outcomes. Whether declines in muscle quantity and quality are an inevitable component of ageing remains to be completely understood. Nevertheless, strategies to mitigate these declines are of vital importance to improve the health span of older adults. This review aims to provide an overview of the declines in skeletal muscle mass and function with advancing age, describes the wide-ranging implications of these declines, and finally suggests strategies to mitigate them, including the merits of emerging pharmaceutical agents.

BackgroundMany adults do not meet physical activity recommendations for optimal health, and this is often because people find it difficult to maintain physical activity in the long term. This study focuses on identifying and synthesising factors that may influence the maintenance of physical activity in adults with and without known health conditions.MethodA systematic review and qualitative synthesis using thematic analysis was conducted. Four databases (MEDLINE, SPORT Discus, APA, and Web of Science) were systematically searched for studies published from inception to February 2023 that included qualitative data about people's experiences of maintaining physical activity.ResultsA total of 9337 abstracts were screened and 68 studies from 14 countries were included. Six main themes were identified: (1) influence of others (e.g. four forms of social support, accountability); (2) contextual and environmental influences (e.g. cost and access of physical activity, weather); (3) health-related influences (e.g. reflexivity about how physical activity improves health conditions, weight control); (4) making it work (e.g. flexibility, prioritising exercise); (5) habits; and (6) psychological processes (e.g. enjoyment, identifying as a physically active person).ConclusionPeople who maintained their participation in physical activity found it enjoyable, prioritised it, and integrated it into their daily routine. Participants were motivated to continue being physically active when they realised the benefits for their health. Social support, in particular companion support, was a key component facilitating continued engagement. Findings specific to maintenance of physical activity included reflexivity of how physical activity benefited health, flexibility, and identifying as a physically active person.

Insulin Resistance (IR) is a component of the pathogenesis of type 2 diabetes mellitus (T2DM), and risk factor for cardiovascular and neurodegenerative diseases. Amino acid and lipid metabolomic IR diagnostics associate with future T2DM risk in epidemiological cohorts. Whether these assays can accurately detect altered IR following treatment has not been established. In the present study we evaluated the ability of metabolomic diagnostics to predict altered IR following exercise treatment. We evaluated the performance of two distinct insulin assays and built combined clinical and metabolomic IR diagnostics. These were utilised to stratify IR status in the pre intervention fasting samples in three independent cohorts (META PREDICT (MP, n=179), STRRIDE AT/RT (S2, n=116) and STRRIDE PD (SPD, n=149)). Linear and Bayesian projective prediction strategies were used to evaluate biomarkers for fasting insulin and HOMA2IR and change in fasting insulin with treatment. Both insulin assays accurately quantified international standard insulin (R2>0.99), yet agreement for fasting insulin was less congruent (R2=0.65). Only the high-sensitivity ELISA assay could identify the mean effect of treatment on fasting insulin. Clinical metabolomic models were statistically related to fasting insulin (R2 0.33 0.39) but had modest capacity to classify HOMA2IR at a clinically relevant threshold. Furthermore, no model predicted treatment responses in any cohort. Thus, we demonstrate that the choice of insulin assay is critical when quantifying the influence of lifestyle on fasting insulin, while none of the clinical metabolomic biomarkers, validated in cross sectional data, are suitable for monitoring longitudinally changes in IR status ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial NCT01920659 ### Funding Statement The clinical data utilised in this study was funded by multiple sources: European Union Seventh Framework Programme (META-PREDICT, HEALTH-F2-2012-277936); STRRIDE II ([NCT00275145][1]) by NHLBI grant HL-057354 and STRRIDE-PD ([NCT00962962][2]) by NIDDK DK-081559 and R01DK081559. The data modelling was supported by Augur Precision Medicine LTD. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study was approved by local ethics committees at all sites (the University of Nottingham Medical School Ethics Committee: D8122011 BMS; the Regional Ethical Review Board Stockholm: 2012/753-31/2; the ethics committee of the municipality of Copenhagen and Frederiksberg in Denmark: H-3-2012-024; Comite etico de Investigacion Humana de la ULPGC: CEIH-2012-02; and the Loughborough University Ethics Approvals Human Participants Sub-Committee: 12/EM/0223) and complied with the 2008 Declaration of Helsinki. To ensure accurate results, we were obliged to discontinue training for individuals who: (i) failed to attend for more than 2 consecutive sessions, (ii) missed more than 3 (~15%) training sessions in total, or (iii) failed to complete their set exercise regime on 2 occasions or more. This was not the case for any participants. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The clinical and metabolomic Data and the analysis script can be found at 10.5281/zenodo.13819578. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00275145&atom=%2Fmedrxiv%2Fearly%2F2024%2F10%2F08%2F2024.10.06.24314962.atom [2]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00962962&atom=%2Fmedrxiv%2Fearly%2F2024%2F10%2F08%2F2024.10.06.24314962.atom