Altered carbohydrate oxidation during exercise in overreached endurance athletes is applicable to training monitoring with continuous glucose monitors.

PURPOSE: The purpose of the study was to investigate whether carbohydrate utilization is altered during exercise in overreached endurance athletes and examine the utility of continuous glucose monitors (CGM) to detect overreaching status. METHODS: Eleven endurance athletes (M:8, F:3) completed a 5-week training block consisting of 1 week of reduced training (PRE), 3 weeks of high-intensity overload training (POST), and 1 week of recovery training (REC). Participants completed a Lamberts and Lambert Submaximal Cycling Test (LSCT) and 5 km time-trial at PRE, POST, and REC time points, 15 min following the ingestion of a 50 g glucose beverage with glucose recorded each minute via CGM. RESULTS: Performance in the 5 km time-trial was reduced at POST (∆-7 ± 10 W, p = 0.04, η p 2 = 0.35) and improved at REC (∆12 ± 9 W from PRE, p = 0.01, η p 2 = 0.66), with reductions in peak lactate (∆-3.0 ± 2.0 mmol/L, p = 0.001, η p 2 = 0.71), peak HR (∆-6 ± 3 bpm, p < 0.001, η p 2 = 0.86), and Hooper-Mackinnon well-being scores (∆10 ± 5 a.u., p < 0.001, η p 2 = 0.79), indicating athletes were functionally overreached. The respiratory exchange ratio was suppressed at POST relative to REC during the 60% (POST: 0.80 ± 0.05, REC: 0.87 ± 0.05, p < 0.001, η p 2 = 0.74), and 80% (POST: 0.93 ± 0.05, REC: 1.00 ± 0.05, p = 0.003, η p 2 = 0.68) of HR-matched submaximal stages of the LSCT. CGM glucose was reduced during HR-matched submaximal exercise in the LSCT at POST (p = 0.047, η p 2 = 0.36), but not the 5 km time-trial (p = 0.07, η p 2 = 0.28) in overreached athletes. CONCLUSION: This preliminary investigation demonstrates a reduction in CGM-derived glucose and carbohydrate oxidation during submaximal exercise in overreached athletes. The use of CGM during submaximal exercise following standardized nutrition could be employed as a monitoring tool to detect overreaching in endurance athletes.

Cannabis containing THC impairs 20-min cycling time trial performance irrespective of the method of inhalation.

Herein, we examine the human exercise response following cannabis inhalation, taking into consideration varied cannabinoid concentrations and different inhalation methods. A semirandomized crossover study design was used, with measures of perceived exertion and physiological responses to submaximal and maximal exercise. Participants (n = 14, 9 males 5 females) completed exercise after 1) smoking Δ-9-tetrahydrocannabinol (THC)-predominant cannabis (S-THC), 2) inhaling aerosol (vaporizing) from THC-predominant cannabis (V-THC), 3) inhaling aerosol from cannabidiol (CBD)-predominant cannabis (V-CBD), or 4) under control conditions. All exercise was performed on a cycle ergometer, with submaximal testing performed at 100 W followed by an evaluation of maximal exercise performance using an all-out 20-min time trial. Metabolism was characterized via the analysis of expired gases while subjective ratings of perceived exertion (RPE) were reported. During submaximal cycling, heart rate was higher during S-THC and V-THC compared with both control and V-CBD (all P < 0.02). During maximal exercise, V̇e was lower in V-THC compared with control, S-THC, and V-CBD (all P < 0.03), as was S-THC compared with control (P < 0.05). Both V̇o2 and RPE were similar between conditions during maximal exercise (both P > 0.1). Mean power output during the 20-min time trial was significantly lower in the S-THC and V-THC conditions compared with both control and V-CBD (all P < 0.04). Cannabis containing THC alters the physiological response to maximal and submaximal exercise, largely independent of the inhalation method. THC-containing cannabis negatively impacts vigorous exercise performance during a sustained 20-min effort, likely due to physiological and psychotropic effects. Inhalation of cannabis devoid of THC and primarily containing CBD has little physiological effect on the exercise response or performance.NEW & NOTEWORTHY Inhalation of cannabis containing THC alters physiological responses to both submaximal and maximal exercise and reduces mean power output during a 20-min time trial, regardless of whether it is inhaled as smoke or aerosol. In contrast, cannabis devoid of THC and predominantly containing CBD has no effect on physiological responses to exercise or performance.

A Characterization of the Cardiac Physiology and Aortic Pulse Wave Properties of Artistic Swimmers Across Competitive Levels.

PURPOSE: The distinct physical and environmental stressors of artistic swimming (previously termed synchronized swimming) result in unique hemodynamic stimuli. Given that the hemodynamic stress associated with participation in an exercise modality drives adaptation of the heart and central vasculature, artistic swimming may produce a distinct cardiovascular phenotype. Presumably, athletes competing at the highest levels also have greater training exposure and, thus, exhibit more adaptation. The purpose of this study was to characterize cardiovascular form and function across the competitive spectrum of artistic swimmers. METHODS: Cardiovascular structure and function were compared in a cross-sectional study of healthy controls, varsity, and elite artistic swimmers, using pulse wave analysis, pulse wave velocity, and echocardiographic images both at rest and during isometric handgrip exercise. RESULTS: Aortic stiffness was similar across all groups, as were characteristics of the decomposed aortic pressure waveform. At rest, both varsity and elite swimmers demonstrated similar systolic function compared to controls. However, peak left ventricular twist was greater in varsity and elites (controls: 8.0 ± 3.9, varsity: 12.8 ± 8.6, elites: 13.4 ± 3.9; both p < 0.02). Furthermore, elites demonstrated greater peak left ventricular radial strain (controls: 29.2 ± 9.9, varsity: 32.5 ± 10.3, elites: 53.9 ± 15.1; both p < 0.001) and longitudinal strain (controls: -16.9 ± 1.6, varsity: -16.5 ± 1.8, elites: -19.5 ± 3.2; both p < 0.04). In contrast to controls, both varsity and elite artistic swimmers demonstrated no change in peak late diastolic transmitral filling velocity (controls: Δ0.2 ± 0.04 m/s, varsity: Δ0.06 ± 0.04 m/s, elites: Δ0.05 ± 0.04 m/s) during isometric handgrip exercise (both p > 0.05), with elites demonstrating lower peak velocity than varsity swimmers, (p = 0.048) indicating preservation of diastolic function. CONCLUSIONS: Artistic swimmers demonstrate distinct cardiac physiology at rest and during isometric handgrip, with a greater extent of distinguishing features observed in those competing at the highest level of competition.