Kristin Lundanes Jonvik

• Weijer, Vera C.R.; Jonvik, Kristin Lundanes; van Dam, Lotte; Risvang, Linn; Raastad, Truls & van Loon, Luc J.C. [Show all 7 contributors for this article] (2024). Measured and Predicted Resting Metabolic Rate of Dutch and Norwegian Paralympic Athletes. Journal of the Academy of Nutrition and Dietetics. ISSN 2212-2672. doi: 10.1016/j.jand.2024.05.010.
• Weijer, Vera C.R.; van Dijk, Jan-Willem; van Dam, Lotte; Risvang, Linn; Bons, Judith & Raastad, Truls [Show all 8 contributors for this article] (2024). Do Paralympic athletes suffer from brittle bones? Prevalence and risk factors of low bone mineral density in Paralympic athletes. Bone Reports. ISSN 2352-1872. 21. doi: 10.1016/j.bonr.2024.101767.
• Weijer, Vera C. R.; Jonvik, Kristin Lundanes; Van Dam, Lotte; Risvang, Linn; Plasqui, Guy & Sandbakk, Øyvind Bucher [Show all 9 contributors for this article] (2024). Energy Requirements of Paralympic Athletes: Insights from the Doubly Labeled Water Approach. Medicine & Science in Sports & Exercise. ISSN 0195-9131. 56(5), p. 963–971. doi: 10.1249/MSS.0000000000003379.
• Jonvik, Kristin Lundanes; Torstveit, Monica Klungland; Sundgot-Borgen, Jorunn & Mathisen, Therese Fostervold (2022). Do we need to change the guideline values for determining low bone mineral density in athletes? [Viewpoint]. Journal of applied physiology. ISSN 8750-7587. 132(5), p. 1320–1322. doi: 10.1152/japplphysiol.00851.2021. Full text in Research Archive
• van Venrooij, Niek F.J.; Wardenaar, Floris C.; Hoogervorst, Daan; Senden, Joan M.G.; van Dijk, Jan-Willem & Jonvik, Kristin Lundanes (2022). The association between gastrointestinal injury, complaints, and food intake in 60-km ultramarathon runners. Applied Physiology, Nutrition and Metabolism. ISSN 1715-5312. 47(5), p. 547–554. doi: 10.1139/apnm-2021-0711. Full text in Research Archive Show summary

  We aimed to assess the association between gastrointestinal (GI) injury, complaints, and food intake in 60-km ultramarathon runners. Thirty-three ultramarathon runners provided pre- and post-race blood samples for assessment of GI injury by intestinal fatty-acid binding protein (I-FABP), and inflammatory response by interleukin (IL)-6, IL-8, tumour necrosis factor alpha (TNF-α), and C-reactive protein (CRP). GI complaints and nutritional intake were reported by a post-race questionnaire. GI complaints were reported by 73% of the runners, of which 20% reported 1 or 2 severe complaints. IL-6, IL8, TNF-α, and CRP increased significantly from pre- to post-race (P < 0.001 for all biomarkers), while I-FABP did not (1375 [IQR: 1264–2073] to 1726 [IQR: 985–3287] pg/mL; P = 0.330). The ‘GI complaints score’, as the integral of the number and severity of GI complaints, did not correlate with ΔI-FABP (rs: –0.050, P = 0.790) or energy intake (rs: 0.211, P = 0.260). However, there was a significant negative correlation between energy intake and ΔI-FABP (rs: –0.388, P = 0.031). In conclusion, GI complaints were neither associated with food intake nor GI injury as assessed by plasma I-FABP response. Energy intake, however, was inversely related to the I-FABP response to exercise. This finding suggests that substantial energy intakes during exercise may prevent exercise-induced GI injury as assessed by the I-FABP response.

• Shannon, Oliver M.; Allen, Jason D.; Bescos, Raul; Burke, Louise; Clifford, Tom & Easton, Chris [Show all 16 contributors for this article] (2022). Dietary Inorganic Nitrate as an Ergogenic Aid: An Expert Consensus Derived via the Modified Delphi Technique. Sports Medicine. ISSN 0112-1642. 52(10), p. 2537–2558. doi: 10.1007/s40279-022-01701-3. Full text in Research Archive Show summary

  Introduction: Dietary inorganic nitrate is a popular nutritional supplement, which increases nitric oxide bioavailability and may improve exercise performance. Despite over a decade of research into the effects of dietary nitrate supplementation during exercise there is currently no expert consensus on how, when and for whom this compound could be recommended as an ergogenic aid. Moreover, there is no consensus on the safe administration of dietary nitrate as an ergogenic aid. This study aimed to address these research gaps. Methods: The modified Delphi technique was used to establish the views of 12 expert panel members on the use of dietary nitrate as an ergogenic aid. Over three iterative rounds (two via questionnaire and one via videoconferencing), the expert panel members voted on 222 statements relating to dietary nitrate as an ergogenic aid. Consensus was reached when > 80% of the panel provided the same answer (i.e. yes or no). Statements for which > 80% of the panel cast a vote of insufficient evidence were categorised as such and removed from further voting. These statements were subsequently used to identify directions for future research. Results: The 12 panel members contributed to voting in all three rounds. A total of 39 statements (17.6%) reached consensus across the three rounds (20 yes, 19 no). In round one, 21 statements reached consensus (11 yes, 10 no). In round two, seven further statements reached consensus (4 yes, 3 no). In round three, an additional 11 statements reached consensus (5 yes, 6 no). The panel agreed that there was insufficient evidence for 134 (60.4%) of the statements, and were unable to agree on the outcome of the remaining statements. Conclusions: This study provides information on the current expert consensus on dietary nitrate, which may be of value to athletes, coaches, practitioners and researchers. The effects of dietary nitrate appear to be diminished in individuals with a higher aerobic fitness (peak oxygen consumption [V̇O2peak] > 60 ml/kg/min), and therefore, aerobic fitness should be taken into account when considering use of dietary nitrate as an ergogenic aid. It is recommended that athletes looking to benefit from dietary nitrate supplementation should consume 8–16 mmol nitrate acutely or 4–16 mmol/day nitrate chronically (with the final dose ingested 2–4 h pre-exercise) to maximise ergogenic effects, taking into consideration that, from a safety perspective, athletes may be best advised to increase their intake of nitrate via vegetables and vegetable juices. Acute nitrate supplementation up to ~ 16 mmol is believed to be safe, although the safety of chronic nitrate supplementation requires further investigation. The expert panel agreed that there was insufficient evidence for most of the appraised statements, highlighting the need for future research in this area.

• Jonvik, Kristin Lundanes; Vardardottir, Birna & Broad, Elizabeth (2022). How Do We Assess Energy Availability and RED-S Risk Factors in Para Athletes? Nutrients. ISSN 2072-6643. 14(5). doi: 10.3390/nu14051068. Full text in Research Archive Show summary

  Low energy availability (LEA) is considered to be the underlying cause of a number of maladaptations in athletes, including impaired physiological function, low bone mineral density (BMD), and hormonal dysfunction. This is collectively referred to as ‘Relative Energy Deficiency in Sport’ (RED-S). LEA is calculated through assessment of dietary energy intake (EI), exercise energy expenditure (EEE) and fat-free mass (FFM). The incidence of LEA in Paralympic athletes is relatively unknown; however, there are legitimate concerns that Para athletes may be at even higher risk of LEA than able-bodied athletes. Unfortunately, there are numerous issues with the application of LEA assessment tools and the criterion for diagnosis within the context of a Para population. The calculation of EEE, in particular, is limited by a distinct lack of published data that cover a range of impairments and activities. In addition, for several RED-S-related factors, it is difficult to distinguish whether they are truly related to LEA or a consequence of the athlete’s impairment and medical history. This narrative review outlines deficits and complexities when assessing RED-S and LEA in Para athletes, presents the information that we do have, and provides suggestions for future progress in this important area of sports nutrition.

• Jonvik, Kristin Lundanes; Torstveit, Monica Klungland; Sundgot-Borgen, Jorunn & Mathisen, Therese Fostervold (2022). Last Word on Viewpoint: Do we need to change the guideline values for determining low bone mineral density in athletes? Journal of applied physiology. ISSN 8750-7587. 132(5), p. 1325–1326. doi: 10.1152/japplphysiol.00227.2022.
• Jonvik, Kristin Lundanes; King, Michelle; Rollo, Ian; Stellingwerff, Trent & Pitsiladis, Yannis (2022). New Opportunities to Advance the Field of Sports Nutrition. Frontiers in Sports and Active Living. ISSN 2624-9367. 4. doi: 10.3389/fspor.2022.852230. Full text in Research Archive Show summary

  Sports nutrition is a relatively new discipline; with ~100 published papers/year in the 1990s to ~3,500+ papers/year today. Historically, sports nutrition research was primarily initiated by university-based exercise physiologists who developed new methodologies that could be impacted by nutrition interventions (e.g., carbohydrate/fat oxidation by whole body calorimetry and muscle glycogen by muscle biopsies). Application of these methods in seminal studies helped develop current sports nutrition guidelines as compiled in several expert consensus statements. Despite this wealth of knowledge, a limitation of the current evidence is the lack of appropriate intervention studies (e.g., randomized controlled clinical trials) in elite athlete populations that are ecologically valid (e.g., in real-life training and competition settings). Over the last decade, there has been an explosion of sports science technologies, methodologies, and innovations. Some of these recent advances are field-based, thus, providing the opportunity to accelerate the application of ecologically valid personalized sports nutrition interventions. Conversely, the acceleration of novel technologies and commercial solutions, especially in the field of biotechnology and software/app development, has far outstripped the scientific communities' ability to validate the effectiveness and utility of the vast majority of these new commercial technologies. This mini-review will highlight historical and present innovations with particular focus on technological innovations in sports nutrition that are expected to advance the field into the future. Indeed, the development and sharing of more “big data,” integrating field-based measurements, resulting in more ecologically valid evidence for efficacy and personalized prescriptions, are all future key opportunities to further advance the field of sports nutrition.

• Jones, Andrew M.; Vanhatalo, Anni; Seals, Douglas R.; Rossman, Matthew J.; Piknova, Barbora & Jonvik, Kristin Lundanes (2020). Dietary Nitrate and Nitric Oxide Metabolism Mouth, Circulation, Skeletal Muscle, and Exercise Performance. Medicine & Science in Sports & Exercise. ISSN 0195-9131. doi: 10.1249/MSS.0000000000002470. Full text in Research Archive Show summary

  Nitric oxide (NO) is a gaseous signaling molecule that plays an important role in myriad physiological processes including the regulation of vascular tone, neurotransmission, mitochondrial respiration and skeletal muscle contractile function. NO may be produced via the canonical NOS-catalyzed oxidation of l-arginine and also by the sequential reduction of nitrate to nitrite and then NO. The body’s nitrate stores can be augmented by the ingestion of nitrate-rich foods (primarily green leafy vegetables). NO bioavailability is greatly enhanced by the activity of bacteria residing in the mouth which reduce nitrate to nitrite, thereby increasing the concentration of circulating nitrite which can be reduced further to NO in regions of low oxygen availability. Recent investigations have focused on promoting this nitrate-nitrite-NO pathway to positively impact indices of cardiovascular health and exercise tolerance. It has been reported that dietary nitrate supplementation with beetroot juice lowers blood pressure in hypertensive patients whereas sodium nitrite supplementation improves vascular endothelial function and reduces stiffening of large elastic arteries in older humans. Nitrate supplementation has also been shown to enhance skeletal muscle function and to improve exercise performance in some circumstances. Recently, it has been established that nitrate concentration in skeletal muscle is much higher than that in blood and that muscle nitrate stores are exquisitely sensitive to dietary nitrate supplementation and deprivation. In this review, we consider the possibility that nitrate represents an essential storage form of NO and discuss the integrated function of the oral microbiome, the circulation and skeletal muscle in nitrate-nitrite-NO metabolism as well as the practical relevance for health and performance.

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• Baumgart, Julia Kathrin; Jonvik, Kristin Lundanes; Severin, Anna Cecilia; Hrozanova, Maria & Solli, Guro Strøm (2023). Parautøveren. In Sandbakk, Øyvind Bucher; Solli, Guro Strøm & Staff, Hanne Cesilie (Ed.), Den kvinnelige idrettsutøveren. Fagbokforlaget. ISSN 9788245036930.
• Mathisen, Therese Fostervold; Jonvik, Kristin Lundanes & Kjellgren, Daniel (2022). "Det grønne skiftet". [Newspaper]. Aftenposten.
• Bieniek, Daniel; Jonvik, Kristin Lundanes; Stormoen, Kristiane; Lekhal, Samira; Mathisen, Therese Fostervold & Sundfør, Tine Mejlbo [Show all 9 contributors for this article] (2022). Flertallet av nordmenn tror fagpersoner er uenige om hva som er sunt. Det stemmer ikke. Forskning.no. ISSN 1891-635X.
• Jonvik, Kristin Lundanes (2021). Unknowns in endrurance nutrition. Gatorade sports science institute.

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