Browsing by Author "Hoogervorst, D."

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The association between gastrointestinal injury, complaints, and food intake in 60-km ultramarathon runners.
Venrooij, N.F.J. van ; Wardenaar, F.C. ; Hoogervorst, D. ; Senden, J.M.G. ; Dijk, J.W. van ; Jonvik, K.L.
2022, Article / Letter to editor (Applied Physiology, Nutrition, and Metabolism, vol. 47, iss. 5, (2022), pp. 547-554)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. Novelty: No association between gastrointestinal complaints and gastrointestinal injury (I-FABP response) or food intake was present. There was an inverse correlation between energy intake and plasma I-FABP response, suggesting that higher energy intakes may prevent gastrointestinal injury as assessed by the I-FABP response.
The impact of beetroot juice supplementation on muscular endurance, maximal strength and countermovement jump performance.
Jonvik, K.L. ; Hoogervorst, D. ; Peelen, H.B. ; Niet, M. de ; Verdijk, L.B. ; Loon, L.J.C. van ; Dijk, J.W. van
2021, Article / Letter to editor (European Journal of Sport Science, vol. 21, iss. 6, (2021), pp. 871-878)Purpose: Dietary nitrate has been shown to enhance muscle contractile function and has, therefore, been linked to increased muscle power and sprint exercise performance. However, the impact of dietary nitrate supplementation on maximal strength, performance and muscular endurance remains to be established. Methods: Fifteen recreationally active males (25 ±4 y, BMI 24 ±3 kg/m(2)) participated in a randomized double-blinded cross-over study comprising two 6-d supplementation periods; 140 mL/d nitrate-rich (BR; 985 mg/d) and nitrate-depleted (PLA; 0.37 mg/d) beetroot juice. Three hours following the last supplement, we assessed countermovement jump (CMJ) performance, maximal strength and power of the upper leg by voluntary isometric (30° and 60° angle) and isokinetic contractions (60, 120, 180 and 300°•s(-1)), and muscular endurance (total workload) by 30 reciprocal isokinetic voluntary contractions at 180°•s(-1). Results: Despite differences in plasma nitrate (BR: 879 ±239 vs. PLA: 33 ±13 μmol/L, Pn<n0.001) and nitrite (BR: 463 ±217 vs. PLA: 176 ±50 nmol/L, Pn<n0.001) concentrations prior to exercise testing, CMJ height (BR: 39.3 ±6.3 vs. PLA: 39.6 ±6.3 cm; Pn=n0.39) and muscular endurance (BR: 3.93 ±0.69 vs. PLA: 3.90 ±0.66 kJ; Pn=n0.74) were not different between treatments. In line, isometric strength (Pn>n0.50 for both angles) and isokinetic knee extension power (Pn>n0.33 for all velocities) did not differ between treatments. Isokinetic knee flexion power was significantly higher following BR compared with PLA ingestion at 60°•s(-1) (Pn=n0.001), but not at 120°•s(-1) (Pn=n0.24), 180°•s(-1) (Pn=n0.066), and 300°•s(-1) (Pn=n0.36). Conclusion: Nitrate supplementation does not improve maximal strength, countermovement jump performance and muscular endurance in healthy, active males.

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