Jørgen Jensen

• Hansen, Anders A.; Egebjerg, Jacob M.; Solem, Kristian; Kolnes, Kristoffer Jensen; Wüstner, Daniel & Wojtaszewski, Jørgen F.P. [Show all 8 contributors for this article] (2026). A semantic segmentation model to predict subcellular glycogen localization using transmission electron microscopy images. PLOS ONE. 21(6 June). doi: 10.1371/journal.pone.0351502. Full text in Research Archive
• Uluvar, Burulça; Williamson, Alice; Kolnes, Kristoffer Jensen; Jeppesen, Per Bendix; Kolnes, Anders Jensen & Koprulu, Mine [Show all 20 contributors for this article] (2026). Tissue origins of the plasma proteomic response to glucose ingestion in humans. Diabetologia. ISSN 0012-186X. doi: 10.1007/s00125-026-06800-8. Full text in Research Archive
• Dæhli, Malin Rasen; Clauss, Matthieu; Skattebo, Øyvind; Johansen, Egil Ivar; Jeppesen, Per B. & Jensen, Jørgen (2026). Caffeine Increases Rate of Fat Oxidation During Exercise in Healthy Young Males and Females. Journal of Science in Sport and Exercise (SSEJ). ISSN 2096-6709. doi: 10.1007/s42978-026-00388-6. Full text in Research Archive
• Kolnes, Kristoffer Jensen; Turner, Lauren V.; Brufladt, Steffen Johnsen; Nilsen, Emelie; Kolnes, Anders Jensen & O’Rahilly, Stephen [Show all 8 contributors for this article] (2026). Marked Increases in Continuous Glucose Monitor-Detected Hypoglycemia During a Seven-Day Water-Only Fast in Healthy Men and Women. Journal of Diabetes Science and Technology. doi: 10.1177/19322968261421956. Full text in Research Archive
• Jensen, Jørgen & Puissant, Claire (2025). Claude Bernard’s route to the isolation of glycogen: the journey that changed scientific views on the physiological role of the liver and animal metabolism. European Journal of Applied Physiology. ISSN 1439-6319. 126(2), p. 629–647. doi: 10.1007/s00421-025-06080-x. Full text in Research Archive
• Solem, Kristian; Clauss, Matthieu & Jensen, Jørgen (2025). Glycogen supercompensation in skeletal muscle after cycling or running followed by a high carbohydrate intake the following days: a systematic review and meta-analysis. Frontiers in Physiology. 16. doi: 10.3389/fphys.2025.1620943. Full text in Research Archive Show summary

  Introduction Bergström and Hultman demonstrated that exhaustive exercise depleting muscle glycogen followed by three days on a carbohydrate-rich diet resulted in a doubling of the glycogen content. Although many studies have confirmed this finding, the magnitude of glycogen supercompensation and the mechanisms behind elevated glycogen content after exercise remain unclear. This systematic review meta-analyzed investigations on muscle glycogen supercompensation after exercise and 3–5 days on a high-carbohydrate diet. Meta-regression analyses were conducted to explore the influence of specific variables on muscle glycogen supercompensation. Methods A systematic search was performed for published studies in PubMed and Web of Science in March 2025. Inclusion criteria were: 1) reported basal glycogen values after a mixed diet; 2) included an exercise session prior to the dietary intervention; 3) utilized high carbohydrate intake after exercise to supercompensate glycogen stores; 4) measured muscle glycogen content after 3–5 days on a high-carbohydrate diet; and 5) reported quantitative data on glycogen. Data were extracted to compare muscle glycogen supercompensation following cycling and running exercises, followed by a 3–5-day high-carbohydrate diet. Meta-analyses were performed using the mean difference (MD) with 95% confidence intervals (CI). Results A total of 30 studies published between 1966 and 2020 were included, comprising 319 participants (271 males and 48 females). Glycogen increased by 269.7 ± 29.2 mmol⋅kg −1 dry weight (dw) (95%CI [212.4, 327.0]; p < 0.001) after cycling exercise and by 156.5 ± 48.6 mmol⋅kg −1 dw (95%CI [61.3, 251.7]; p = 0.001) after running exercise. Muscle glycogen supercompensation after cycling was positively associated with percent carbohydrate in the diet (p < 0.001) and negatively associated with basal glycogen concentration (p = 0.011) and glycogen concentration after exercise (p < 0.001). Conclusion Muscle glycogen supercompensation occurs following both cycling and running after 3–5 days on a high-carbohydrate diet, with a greater magnitude observed after cycling compared to running. The magnitude of glycogen supercompensation after cycling is influenced by basal glycogen levels, glycogen content after exercise, and the relative carbohydrate content of the diet.

• Kolnes, Kristoffer Jensen; Nilsen, Emelie; Brufladt, Steffen Johnsen; Meadows, Allison; Jeppesen, Per Bendix & Skattebo, Øyvind [Show all 17 contributors for this article] (2025). Effects of seven days’ fasting on physical performance and metabolic adaptation during exercise in humans. Nature Communications. 16(1). doi: 10.1038/s41467-024-55418-0. Full text in Research Archive Show summary

  Humans have, throughout history, faced periods of starvation necessitating increased physical effort to gather food. To explore adaptations in muscle function, 13 participants (7 males and 6 females) fasted for seven days. They lost 4.6 ± 0.3 kg lean and 1.4 ± 0.1 kg fat mass. Maximal isometric and isokinetic strength remained unchanged, while peak oxygen uptake decreased by 13%. Muscle glycogen was halved, while expression of electron transport chain proteins was unchanged. Pyruvate dehydrogenase kinase 4 (PDK4) expression increased 13-fold, accompanied by inhibitory pyruvate dehydrogenase phosphorylation, reduced carbohydrate oxidation and decreased exercise endurance capacity. Fasting had no impact on 5’ AMP-activated protein kinase (AMPK) activity, challenging its proposed role in muscle protein degradation. The participants maintained muscle strength and oxidative enzymes in skeletal muscle during fasting but carbohydrate oxidation and high-intensity endurance capacity were reduced.

• Clauss, Matthieu & Jensen, Jørgen (2025). Effect of Exercise Intensity, Duration, and Volume on Protein Oxidation During Endurance Exercise in Humans: A Systematic Review With Meta-Analysis. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 35(4). doi: 10.1111/sms.70038. Full text in Research Archive Show summary

  Proteins are degraded and amino acids are metabolized in different quantities during endurance exercise. However, a clear consensus on protein oxidation during exercise has yet to be established. The main objective was to calculate estimates of protein oxidation during endurance exercise using available data. Additionally, we aimed to investigate the effects of exercise intensity, duration, and volume on protein oxidation. We systematically searched for research studies published in English in the online databases PubMed and Google Scholar in March 2023. The inclusion criteria were: (1) measurement of protein metabolism with nitrogen excretion, leucine oxidation, or indicator amino acid utilization method; (2) inclusion of an endurance exercise condition and a control condition without exercise; (3) inclusion of a description of the endurance exercise protocol (duration, intensity); and (4) inclusion of healthy participants over the age of 18. Endurance exercises were defined as exercise periods of at least 60 min' duration of running, cycling, or cross-country skiing. We included 30 articles (n = 286 participants). Protein oxidation increased by 1.02 ± 0.06 mg∙kg−1∙min−1 (95% CI [0.91, 1.14]) during endurance exercise, from the level of 0.81 ± 0.38 mg∙kg−1∙min−1 measured without exercise. Protein contributed 3.28% ± 0.15% (95% CI [2.97, 3.58]) of the total energy expenditure during exercise. Protein oxidation normalized by exercise duration significantly increased with exercise intensity. This review is the first to aggregate data on protein oxidation during endurance exercise, measured using different methods. Endurance exercise consistently increased protein oxidation, with protein metabolism more than doubling during exercise compared to rest. Protein oxidation increased with exercise intensity, but neither exercise duration nor volume augmented the rate of protein oxidation.

• Pietzner, Maik; Uluvar, Burulca; Kolnes, Kristoffer Jensen; Jeppesen, Per Bendix; Frivold, Victoria & Skattebo, Øyvind [Show all 14 contributors for this article] (2024). Systemic proteome adaptions to 7-day complete caloric restriction in humans. Nature Metabolism. 6, p. 764–777. doi: 10.1038/s42255-024-01008-9. Full text in Research Archive Show summary

  Surviving long periods without food has shaped human evolution. In ancient and modern societies, prolonged fasting was/is practiced by billions of people globally for religious purposes, used to treat diseases such as epilepsy, and recently gained popularity as weight loss intervention, but we still have a very limited understanding of the systemic adaptions in humans to extreme caloric restriction of different durations. Here we show that a 7-day water-only fast leads to an average weight loss of 5.7 kg (±0.8 kg) among 12 volunteers (5 women, 7 men). We demonstrate nine distinct proteomic response profiles, with systemic changes evident only after 3 days of complete calorie restriction based on in-depth characterization of the temporal trajectories of ~3,000 plasma proteins measured before, daily during, and after fasting. The multi-organ response to complete caloric restriction shows distinct effects of fasting duration and weight loss and is remarkably conserved across volunteers with >1,000 significantly responding proteins. The fasting signature is strongly enriched for extracellular matrix proteins from various body sites, demonstrating profound non-metabolic adaptions, including extreme changes in the brain-specific extracellular matrix protein tenascin-R. Using proteogenomic approaches, we estimate the health consequences for 212 proteins that change during fasting across ~500 outcomes and identified putative beneficial (SWAP70 and rheumatoid arthritis or HYOU1 and heart disease), as well as adverse effects. Our results advance our understanding of prolonged fasting in humans beyond a merely energy-centric adaptions towards a systemic response that can inform targeted therapeutic modulation.

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• Clauss, Matthieu; Puissant, Clair; Bastani, Nasser Ezzatkhah; Nielsen, Lotte L. K.; Skålhegg, Bjørn Steen & Jeppesen, Per Bendix [Show all 7 contributors for this article] (2025). Effect of high intakes of protein-only and carbohydrate-only on plasma metabolites and hormones, in addition to nitrogen excretion. doi: 10.1007/978-1-0716-4414-0_16. Full text in Research Archive

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