Conduct problems, hyperactivity, and screen time among community youth: can mindfulness help? an exploratory study.

Background: The influence of mindfulness-based intervention (MBI) programs on behavioural problems among community youth is largely understudied. While technology continues to evolve and the prevalence of screen-based activities is rising, limited studies have accounted for screen time when examining the efficacy of an MBI. Accordingly, this study investigated the impact of MBI on conduct problems and hyperactivity among community youth, accounting for sociodemographic characteristics and four types of screen time. Method: Linear regression models were used to investigate 1) the association between four types of screen time and behavioural problems (i.e., conduct problems and hyperactivity) and 2) the efficacy of online mindfulness programs in reducing behavioural problems among community youth. The data were collected at baseline, intervention completion and 1-month follow-up (Spring 2021 to Spring 2022) in Ontario, Canada (n=117, mean age=16.82, male=22%, non-White=21%). Results: The average score for conduct problems was within the normal range, while the average score for hyperactivity was considered borderline at baseline. Accounting for other types of screen time, time spent playing video games was significantly associated with increased conduct problems (ß= 1.75, p=.03), albeit rendering non-significant after correcting for multiple comparisons. The online mindfulness program was significantly associated with reduced hyperactivity, controlling for baseline mental health, age, sex and screen time. Conclusion: The current findings suggest a 12-week online mindfulness program may play a positive role in reducing hyperactivity even when accounting for screen time. Our findings advocate the evidence base on the efficacy of MBI in managing hyperactivity.

Can mindfulness play a role in building social-emotional capacities among youth exposed to screens?

Introduction: Increased screen time coupled with public safety restrictions may pose a serious challenge to adequate social-emotional development in youth during the pandemic. Social-emotional competence (resilience, self-esteem, and self-compassion) are essential for youth to adapt to the "new normal" in the prolonged pandemic timeline. The current study investigated the efficacy of a mindfulness-based intervention on youth social-emotional capacity while accounting for screen time. Methods: One hundred and seventeen youth participated in a 12-week, online mindfulness-based program and completed pre-, post- and follow-up surveys across five cohorts during the COVID-19 pandemic (spring 2021 to spring 2022). Changes in youths' resilience (RS), self-esteem (SE), and self-compassion (SC) between the three-time points were examined using linear regression analyses (unadjusted, partially adjusted for screen time, and fully adjusted for demographic and screen time variables). The regression models accounted for demographic (age, sex), baseline mental health status, and screen time (passive, social media, video games, and educational types of screen-based behaviours) factors. Results: In an unadjusted regression model, resilience [ß = 3.68, 95%CI = 1.78-5.50, p < 0.001], self-compassion [ß = 0.50, 95%CI = 0.34-0.66, p < 0.001], and self-esteem [ß = 2.16, 95%CI = 0.98-3.34, p < 0.001] significantly increased after the mindfulness program, and the effects were maintained in the follow-up. The efficacy of the mindfulness program persisted after controlling for five types of screen time [RS: ß = 2.73, 95%CI = 0.89-4.57, p < 0.01; SC: ß = 0.50, 95%CI = 0.32-0.67, p < 0.001; SE: ß = 1.46, 95%CI = 0.34-2.59, p < 0.01] and in a fully adjusted model which additionally accounted for the baseline mental health status and demographic factors [RS: ß = 3.01, 95%CI = 1.20, p < 0.01; SC: ß = 0.51, 95%CI = 0.33-0.68, p < 0.001; SE: ß = 1.64, 95%CI = 0.51-2.77, p < 0.01] and maintained its impact in the follow-up. Discussion: Our findings reinforce the evidence base on the efficacy of mindfulness and support the use of online mindfulness programs in building social-emotional competencies (i.e., self-compassion, self-esteem, and resilience) among youth exposed to screens during the pandemic.

Exogenous Ketone Salt Supplementation and Whole-Body Cooling Do Not Improve Short-Term Physical Performance.

Exogenous ketone supplementation and whole-body cooling (WBC) have shown to independently influence exercise metabolism. Whether readily available ketone salts, with and without WBC, would provide similar metabolic benefits during steady-state aerobic and time-trial performances was investigated. Nine active males (VO2peak: 56.3 ± 2.2 mL·kg-1·min-1) completed three single-blind exercise sessions preceded by: (1) ingestion of placebo (CON), (2) ketone supplementation (0.3 g·kg-1 ß-OHB) (KET), and (3) ketone supplementation with WBC (KETCO). Participants cycled in steady-state (SS, 60% W max) condition for 30-min, immediately followed by a 15-min time trial (TT). Skin and core temperature, cardio-metabolic, and respiratory measures were collected continuously, whereas venous blood samples were collected before and after supplementation, after SS and TT. Venous ß-OHB was elevated, while blood glucose was lower, with supplementation vs. CON (p < 0.05). TT power output was not different between conditions (p = 0.112, CON: 190 ± 43.5 W, KET: 185 ± 40.4 W, KETCO: 211 ± 50.7 W). RER was higher during KETCO (0.97 ± 0.09) compared to both CON (0.88 ± 0.04, p = 0.012) and KET (0.88 ± 0.05, p = 0.014). Ketone salt supplementation and WBC prior to short-term exercise sufficiently increase blood ß-OHB concentrations, but do not benefit metabolic shifts in fuel utilization or improve time trial performance.

Metabolic flexibility is unimpaired during exercise in the cold following acute glucose ingestion in young healthy adults.

PURPOSE: Metabolic flexibility is compromised in individuals suffering from metabolic diseases, lipo- and glucotoxicity, and mitochondrial dysfunctions. Exercise studies performed in cold environments have demonstrated an increase in lipid utilization, which could lead to a compromised substrate competition, glycotoxic-lipotoxic state, or metabolic inflexibility. Whether metabolic flexibility is altered during incremental maximal exercise to volitional fatigue in a cold environment remains unclear. METHODS: Ten young healthy participants performed four maximal incremental treadmill tests to volitional fatigue, in a fasted state, in a cold (0 °C) or a thermoneutral (22.0 °C) environment, with and without a pre-exercise ingestion of a 75-g glucose solution. Metabolic flexibility was assessed via indirect calorimetry using the change in respiratory exchange ratio (ΔRER), maximal fat oxidation (ΔMFO), and where MFO occurred along the exercise intensity spectrum (ΔFatmax), while circulating lactate and glucose levels were measured pre and post exercise. RESULTS: Multiple linear mixed-effects regressions revealed an increase in glucose oxidation from glucose ingestion and an increase in lipid oxidation from the cold during exercise (p < 0.001). No differences were observed in metabolic flexibility as assessed via ΔRER (0.05 ± 0.03 vs. 0.05 ± 0.03; p = 0.734), ΔMFO (0.21 ± 0.18 vs. 0.16 ± 0.13 g min-1; p = 0.133) and ΔFatmax (13.3 ± 19.0 vs. 0.6 ± 21.3 %V̇O2peak; p = 0.266) in cold and thermoneutral, respectively. CONCLUSIONS: Following glucose loading, metabolic flexibility was unaffected during exercise to volitional fatigue in a cold environment, inducing an increase in lipid oxidation. These results suggest that competing pathways responsible for the regulation of fuel selection during exercise and cold exposure may potentially be mechanistically independent. Whether long-term metabolic influences of high-fat diets and acute lipid overload in cold and warm environments would impact metabolic flexibility remain unclear.

Maximal Fat Oxidation: Comparison between Treadmill, Elliptical and Rowing Exercises.

Fat oxidation during exercise is associated with cardio-metabolic benefits, but the extent of which whole-body exercise modality elicits the greatest fat oxidation remains unclear. We investigated the effects of treadmill, elliptical and rowing exercise on fat oxidation in healthy individuals. Nine healthy males participated in three, peak oxygen consumption tests, on a treadmill, elliptical and rowing ergometer. Indirect calorimetry was used to assess maximal oxygen consumption (V̇O2peak), maximal fat oxidation (MFO) rates, and the exercise intensity MFO occurred (Fatmax). Mixed venous blood was collected to assess lactate and blood gases concentrations. While V̇O2peak was similar between exercise modalities, MFO rates were higher on the treadmill (mean ± SD; 0.61 ± 0.06 g·min-1) compared to both the elliptical (0.41 ± 0.08 g·min-1, p = 0.022) and the rower (0.40 ± 0.08 g·min-1, p = 0.017). Fatmax values were also significantly higher on the treadmill (56.0 ± 6.2 %V̇O2peak) compared to both the elliptical (36.8 ± 5.4 %V̇O2peak, p = 0.049) and rower (31.6 ± 5.0 %V̇O2peak, p = 0.021). Post-exercise blood lactate concentrations were also significantly lower following treadmill exercise (p = 0.021). Exercising on a treadmill maximizes fat oxidation to a greater extent than elliptical and rowing exercises, and remains an important exercise modality to improve fat oxidation, and consequently, cardio-metabolic health.

High-intensity interval exercise in the cold regulates acute and postprandial metabolism.

High-intensity interval exercise (HIIE) has been shown to be more effective than moderate-intensity exercise for increasing acute lipid oxidation and lowering blood lipids during exercise and postprandially. Exercise in cold environments is also known to enhance lipid oxidation; however, the immediate and long-term effects of HIIE exercise in cold are unknown. The purpose of this study was to examine the effects cold stress during HIIE on acute exercise metabolism and postprandial metabolism. Eleven recreationally active individuals (age: 23 ± 3 yr, weight: 80 ± 9.7 kg, V̇O2peak: 39.2 ± 5.73 mL·kg-1·min-1) performed evening HIIE sessions (10 × 60 s cycling, 90% V̇O2peak interspersed with 90 s active recovery, 30% V̇O2peak) in thermoneutral (HIIE-TN, control; 21°C) and cold environment (HIIE-CO; 0°C), following a balanced crossover design. The following morning, participants consumed a high-fat meal. Indirect calorimetry was used to assess substrate oxidation, and venous blood samples were obtained to assess changes in noncellular metabolites. During acute exercise, lipid oxidation was higher in HIIE-CO (P = 0.002) without differences in V̇O2 and energy expenditure (P ≥ 0.162) between conditions. Postprandial V̇O2, lipid and CHO oxidation, plasma insulin, and triglyceride concentrations were not different between conditions (P > 0.05). Postprandial blood LDL-C levels were higher in HIIE-CO 2 h after the meal (P = 0.003). Postprandial glucose area under curve was 49% higher in HIIE-CO versus HIIE-TN (P = 0.034). Under matched energy expenditure conditions, HIIE demonstrated higher lipid oxidation rates during exercise in the cold; but only marginally influenced postprandial lipid metabolism the following morning. In conclusion, HIIE in the cold seemed to be less favorable for postprandial lipid and glycemic responses.NEW & NOTEWORTHY This is the first known study to investigate the effects of cold ambient temperatures on acute metabolism during high-intensity interval exercise, as well as postprandial metabolism the next day. We observed that high-intensity interval exercise in a cold environment does change acute metabolism compared to a thermoneutral environment; however, the addition of a cold stimulus was less favorable for postprandial metabolic responses the following day.

Muscle cooling modulates tissue oxidative and biochemical responses but not energy metabolism during exercise.

PURPOSE: This study investigated whether muscle cooling and its associated effects on skeletal muscle oxidative responses, blood gases, and hormonal concentrations influenced energy metabolism during cycling. METHODS: Twelve healthy participants (Males: seven; Females: five) performed two steady-state exercise sessions at 70% of ventilatory threshold on a cycle ergometer. Participants completed one session with pre-exercise leg cooling until muscle temperature (Tm) decreased by 6 °C (LCO), and a separate session without cooling (CON). They exercised until Tm returned to baseline and for an additional 30 min. Cardiovascular, respiratory, metabolic, hemodynamic variables, and skeletal muscle tissue oxidative responses were assessed continuously. Venous blood samples were collected to assess blood gases, and hormones. RESULTS: Heart rate, stroke volume, and cardiac output all increased across time but were not different between conditions. V̇O2 was greater in LCO when muscle temperature was restored until the end of exercise (p < 0.05). Cycling in the LCO condition induced lower oxygen availability, tissue oxygenation, blood pH, sO2%, and pO2 (p < 0.05). Insulin concentrations were also higher in LCO vs. CON (p < 0.05). Importantly, stoichiometric equations from respiratory gases indicated no differences in fat and CHO oxidation between conditions. CONCLUSION: The present study demonstrated that despite muscle cooling and the associated oxidative and biochemical changes, energy metabolism remained unaltered during cycling. Whether lower local and systemic oxygen availability is counteracted via a cold-induced activation of lipid metabolism pathways needs to be further investigated.