Neither Beetroot Juice Supplementation nor Increased Carbohydrate Oxidation Enhance Economy of Prolonged Exercise in Elite Race Walkers.

Given the importance of exercise economy to endurance performance, we implemented two strategies purported to reduce the oxygen cost of exercise within a 4 week training camp in 21 elite male race walkers. Fourteen athletes undertook a crossover investigation with beetroot juice (BRJ) or placebo (PLA) [2 d preload, 2 h pre-exercise + 35 min during exercise] during a 26 km race walking at speeds simulating competitive events. Separately, 19 athletes undertook a parallel group investigation of a multi-pronged strategy (MAX; n = 9) involving chronic (2 w high carbohydrate [CHO] diet + gut training) and acute (CHO loading + 90 g/h CHO during exercise) strategies to promote endogenous and exogenous CHO availability, compared with strategies reflecting lower ranges of current guidelines (CON; n = 10). There were no differences between BRJ and PLA trials for rates of CHO (p = 0.203) or fat (p = 0.818) oxidation or oxygen consumption (p = 0.090). Compared with CON, MAX was associated with higher rates of CHO oxidation during exercise, with increased exogenous CHO use (CON; peak = ~0.45 g/min; MAX: peak = ~1.45 g/min, p < 0.001). High rates of exogenous CHO use were achieved prior to gut training, without further improvement, suggesting that elite athletes already optimise intestinal CHO absorption via habitual practices. No differences in exercise economy were detected despite small differences in substrate use. Future studies should investigate the impact of these strategies on sub-elite athletes' economy as well as the performance effects in elite groups.

Acute human exposure assessment to tetrahydrocannabinol (Δ9-THC).

Delta-9-tetrahydrocannabinol (Δ9-THC) is a naturally occurring psychoactive compound derived from the hemp plant Cannabis sativa. In 2015, EFSA established an acute reference dose (ARfD) of 1 µg/kg body weight (bw) for Δ9-THC and assessed acute dietary exposure from milk and dairy products. This resulted at the most 3% and 13% of the ARfD for adults and toddlers, respectively. Following the European Commission Recommendation 2016/2115 on the monitoring of the presence of Δ9-THC in food and the issuing of a new mandate, EFSA assessed the acute human exposure to Δ9-THC. 'Standard' food categories were used as proxies for consumption of hemp and hemp-based products. Twelve independent scenarios based on single food categories were considered and acute exposure was assessed for consumption days only for all age groups excluding infants. Occurrence data for Total-Δ9-THC (588 samples in total) were used for this assessment up to the highest reliable percentile for each food category. The EFSA ARfD of 1 µg/kg bw was exceeded in the adult high consumers of most considered hemp and hemp-containing products, under the lower-bound (LB) and upper-bound (UB) scenario. At the UB, acute exposure in adult high consumers was estimated based on the highest reliable percentile of occurrence, for Hemp seeds (P95, up to 9 µg/kg bw), Hemp oil (P95, up to 21 µg/kg bw), Tea (Infusion) (P95, up to 208 µg/kg bw), Breakfast cereals (P50, up to 1.3 µg/kg bw), Pasta (Raw) (P75, up to 6.4 µg/kg bw), Bread and rolls (P75, up to 1.3 µg/kg bw), Bread and rolls from hemp flour (P90, up to 4.1 µg/kg bw), Cereal bars (P50, up to 0.3 µg/kg bw), Fine bakery wares (P75, up to 5.1 µg/kg bw), Chocolate (Cocoa) products (P75, up to 1.1 µg/kg bw), Energy drinks (P75, up to 0.2 µg/kg bw), Dietary supplements (P75, up to 9.9 µg/kg bw), Beer and beer-like beverages (P90, up to 41 µg/kg bw). The use of proxies for the consumption of hemp and hemp-containing products, the limited number of occurrence data and the analytical limitations in the quantification of Δ9-THC represent the most important sources of uncertainty. Overall, exposure estimates presented in this report are expected to represent an overestimation of acute exposure to Δ9-THC in the EU.