Patterns of energy availability of free-living athletes display day-to-day variability that is not reflected in laboratory-based protocols: Insights from elite male road cyclists

The physiological effects of low energy availability (EA) have been studied using a homogenous daily EA pattern in laboratory settings. However, whether this daily EA pattern represents those of free-living athletes and is therefore ecologically valid is unknown. To investigate this, we assessed daily exercise energy expenditure, energy intake and EA in 10 free-living elite male road cyclists (20 min Mean Maximal Power: 5.27 ± 0.25 W · kg−1) during 7 consecutive days of late pre-season training. Energy intake was measured using the remote-food photography method and exercise energy expenditure estimated from cycling crank-based power-metres. Seven-day mean ± SD energy intake and exercise energy expenditure was 57.9 ± 10.4 and 38.4 ± 8.6 kcal · kg FFM−1 · day−1, respectively. EA was 19.5 ± 9.1 kcal · kg FFM−1 · day−1. Within-participants correlation between daily energy intake and exercise energy expenditure was .62 (95% CI: .43 – .75; P < .001), and .60 (95% CI: .41 – .74; P < .001) between carbohydrate intake and exercise energy expenditure. However, energy intake only partially compensated for exercise energy expenditure, increasing 210 kcal · day−1 per 1000 kcal · day−1 increase in expenditure. EA patterns displayed marked day-to-day fluctuation (range: −22 to 76 kcal · kg FFM−1 · day−1). The validity of research using homogenous low EA patterns therefore requires further investigation

Effect of exogenous application of salt stress and glutamic acid on lettuce (Lactuca sativa L.)

Salinity is a serious environmental issue which can negatively affect crop growth and productivity worldwide. Lettuce is generally considered as a salt-sensitive crop; however, different cultivars may have different adaptive mechanisms to this environmental stress. The application of biostimulants has proven to be a strategic strategy to improve plant responses to abiotic stresses and to foster resilience of crops during cultivation. This study intended to explore the physiological mechanisms underlying Romaine lettuce plant responses to salt stress, also in combination with the exogenous application of glutamic acid. The glutamic acid treatment was applied as foliar spray for the first time before salt exposure, followed by three applications during the stress. To understand the effect of salinity and glutamic acid treatment, different physiological and molecular analytical determinations were performed. High salinity induced a general stimulation of PSII and chlorophyll content. In particular, the performance index (+102%) and the number of reaction centres per cross section (+75,7%) increased, whereas the energy dissipation as heat per reaction centres (-32,1%) and the net rate of the centres’ closure (Mo) (-39.4%) decreased. Moreover, a reduction of yield (-26,5%) was observed in plants grown under high salinity. The concentration of proline was stimulated by salinity whereas ABA levels were reduced. The analyses of the genes encoding for ROS scavenging enzymes showed a general downregulation in response to salinity with the only exception of LsSOD. The application of the glutamic acid did not show a clear effect of the amino acid on lettuce plants, regardless the different growing conditions