Øyvind Skattebo

• 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
• Skattebo, Øyvind; Martin-Rincon, Marcos; Calbet, Jose Antonio Lopez; Hallén, Jostein & Holmberg, Hans-Christer (2026). A Review of Central and Peripheral Limitations to Endurance Exercise Performance on the Road to the Milano-Cortina 2026 Olympics. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 36(3). doi: 10.1111/sms.70266. Full text in Research Archive
• Zambolin, Fabio; Vikmoen, Olav; Cumming, Kristoffer Toldnes; Skattebo, Øyvind; Ødemark, Hege Nymo & Øfsteng, Sjur Fortun [Show all 10 contributors for this article] (2026). Similar performance and muscle adaptations between intervals with and without blood flow restriction in well-trained cyclists. Journal of applied physiology. ISSN 8750-7587. 140, p. 699–709. doi: 10.1152/japplphysiol.01038.2025. Full text in Research Archive Show summary

  Background: Blood flow restriction (BFR) allows exercise at lower external load with similar or greater improvements compared with traditional training in non-trained individuals. However, the effect in well-trained competitive athletes is unclear. The aim of this study was to compare effort-matched high-intensity interval training (HIIT) microcycles performed with or without BFR on endurance performance and muscular adaptations in well-trained cyclists. Methods: 17 well-trained cyclists (31 ± 9 years; VO2max: 67 ± 6ml×kg-1×min-1) were randomized to groups performing five HIIT sessions (6 x 5 min intervals with 2.5 min of recovery) with (BFR) or without (HIIT) thigh cuffs occluding the legs. VO2max, power output at 4 mmoL/L blood lactate (LT4), mean power output during 5-minute maximal cycling (MPO5min), percentage of VO2max used at LT4 (%VO2max @LT4), haemoglobin mass and blood volume (BV) were assessed. Muscle biopsies from m. vastus lateralis evaluated muscle cross-sectional area (CSA), capillaries, citrate synthase (CS), Hydroxyacyl-Coenzyme A dehydrogenase (HADH) and cytochrome c oxidase 4 (COX4). Results: The BFR group trained at a 42% lower power output than HIIT group (177±3 W vs 307±8 W, respectively, p<0.01), but with no differences in heart rate or rate of perceived exertion. Both groups improved MPO5min by ⁓4%, with no changes in LT4, VO2max, haemoglobin mass and BV. HIIT showed a significant reduction in CSA for type 2 muscle fibers compared with BFR, whereas no changes were found in the other muscle analyses. Conclusions: BFR applied during a 6-day interval microcycle provides similar performance gains as traditional HIIT in well-trained cyclists.

• Skattebo, Øyvind; Martin-Rincon, Marcos; Rud, Bjarne; Nielsen, Joachim; Hegg, Lars Henrik N. & Kleive, Andreas Vileid [Show all 12 contributors for this article] (2025). Determinants of maximal oxygen uptake in highly trained females and males: a mechanistic study of sex differences using advanced invasive methods. Journal of Physiology. ISSN 0022-3751. doi: 10.1113/JP289218. Full text in Research Archive
• 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.

• Leahy, Michael G.; Thompson, Kyle M. A.; Skattebo, Øyvind; Paz, Jose A. de; Martin-Rincon, Marcos & Garcia-Gonzalez, Eduardo [Show all 11 contributors for this article] (2024). Assessing Leg Blood Flow and Cardiac Output During Running Using Thermodilution. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 34(8). doi: 10.1111/sms.14705. Full text in Research Archive Show summary

  Cardiac output (Q̇C) and leg blood flow (Q̇LEG) can be measured simultaneously with high accuracy using transpulmonary and femoral vein thermodilution with a single-bolus injection. The invasive measure has offered important insight into leg hemodynamics and blood flow distribution during exercise. Despite being the natural modality of exercise in humans, there has been no direct measure of Q̇LEG while running in humans. We sought to determine the feasibility of the thermodilution technique for measuring Q̇LEG and conductance during high-intensity running, in an exploratory case study. A trained runner (30 years male) completed two maximal incremental tests on a cycle ergometer and motorized treadmill. Q̇LEG and Q̇C were determined using the single-bolus thermodilution technique. Arterial and venous blood were sampled throughout exercise, with continuous monitoring of metabolism, intra-arterial and venous pressure, and temperature. The participant reached a greater peak oxygen uptake (V̇O2peak) during running relative to cycling (74 vs. 68 mL/kg/min) with comparable Q̇LEG (19.0 vs. 19.5 L/min) and Q̇C (27.4 vs. 26.2 L/min). Leg vascular conductance was greater during high-intensity running relative to cycling (82 vs. 70 mL/min/mmHg @ ~80% V̇O2peak). The “beat phenomenon” was apparent in femoral flow while running, producing large gradients in conductance (62–90 mL/min/mmHg @ 70% V̇O2peak). In summary, we present the first direct measure of Q̇LEG and conductance in a running human. Our findings corroborate several assumptions about Q̇LEG during running compared with cycling. Importantly, we demonstrate that using thermodilution in running exercise can be completed effectively and safely.

• 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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• Grindaker, Eirik; Mølmen, Knut Sindre; Skattebo, Øyvind; Almquist, Nicki Winfield & Lognseth, Stig (2024). Over 50 år med treningsforskning: hva gir best treningseffekter av langkjøring, hardintervaller eller sprinttrening? doi: https:/api.spreaker.com/v2/episodes/62637510/download.mp3. Full text in Research Archive Show summary

  I denne episoden presenterer og diskuterer vi funn fra en forskningsartikkel som undersøkte hvordan ulike treningsformer påvirker mitokondriemengden og kapillærtettheten til muskulaturen – faktorer som er avgjørende for aerob kapasitet og helse.

• Sperlich, Billy; Holmberg, Hans-Christer; Martin-Rincon, Marcos; Skattebo, Øyvind; Burr, Jamie F. & Hallén, Jostein [Show all 8 contributors for this article] (2024). Repeated Carbon Monoxide Inhalation in Sports: A New Frontier or a Dangerous Gamble? Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 34(12). doi: 10.1111/sms.70005. Full text in Research Archive
• Grindaker, Eirik; Mølmen, Knut Sindre; Almquist, Nicki Winfield & Skattebo, Øyvind (2024). Over 50 år med treningsforskning: hva gir best treningseffekter av langkjøring, hardintervaller og sprinttrening? [Radio]. Podkasten "Trening". Full text in Research Archive

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