Dietary supplementation with New Zealand blackcurrant extract enhances fat oxidation during submaximal exercise in the heat

Objectives. This study investigated the effect of 7 days’ supplementation with New Zealand blackcurrant extract on thermoregulation and substrate metabolism during running in the heat. Design. Randomized, double-blind, cross-over study. Methods. Twelve men and six women (mean ± SD: Age 27 ± 6 years, height 1.76 ± 0.10 m, mass 74 ± 12 kg, V˙ O2max 53.4 ± 7.0 mL kg−1 min−1) completed one assessment of maximal aerobic capacity and one familiarisation trial (18 ◦C, 40% relative humidity, RH), before ingesting 2 × 300 mg day−1 capsules of CurraNZTM (each containing 105 mg anthocyanin) or a visually matched placebo (2 × 300 mg microcrystalline cellulose M102) for 7days (washout 14 days). On day 7 of each supplementation period, participants completed 60 min of fasted running at 65% V˙ O2max in hot ambient conditions (34 ◦C and 40% relative humidity). Results: Carbohydrate oxidation was decreased in the NZBC trial [by 0.24 g min−1 (95% CI: 0.21–0.27 g min-1)] compared to placebo (p = 0.014, d = 0.46), and fat oxidation was increased in the NZBC trial [by 0.12 g min−1 (95% CI: 0.10 to 0.15 g min−1)], compared to placebo (p = 0.008, d = 0.57). NZBC did not influence heart rate (p = 0.963), rectal temperature (p = 0.380), skin temperature (p = 0.955), body temperature (p = 0.214) or physiological strain index (p = 0.705) during exercise. Conclusions. Seven-days intake of 600 mg NZBC extract increased fat oxidation without influencing cardiorespiratory or thermoregulatory variables during prolonged moderate intensity running in hot conditions

Muscle dysmorphia: Could it be classified as an addiction to body image?

BACKGROUND: Muscle dysmorphia (MD) describes a condition characterised by a misconstrued body image in which individuals who interpret their body size as both small or weak even though they may look normal or highly muscular. MD has been conceptualized as a type of body dysmorphic disorder, an eating disorder, and obsessive–compulsive disorder symptomatology. METHOD AND AIM: Through a review of the most salient literature on MD, this paper proposes an alternative classification of MD – the ‘Addiction to Body Image’ (ABI) model – using Griffiths (2005) addiction components model as the framework in which to define MD as an addiction. RESULTS: It is argued the addictive activity in MD is the maintaining of body image via a number of different activities such as bodybuilding, exercise, eating certain foods, taking specific drugs (e.g., anabolic steroids), shopping for certain foods, food supplements, and the use or purchase of physical exercise accessories). In the ABI model, the perception of the positive effects on the self-body image is accounted for as a critical aspect of the MD condition (rather than addiction to exercise or certain types of eating disorder). CONCLUSIONS: Based on empirical evidence to date, it is proposed that MD could be re-classified as an addiction due to the individual continuing to engage in maintenance behaviours that may cause long-term harm

The impact of submaximal exercise during heat and/or hypoxia on the cardiovascular and monocyte HSP72 responses to subsequent (post 24 h) exercise in hypoxia

BACKGROUND: The aims of this study were to describe the cellular stress response to prolonged endurance exercise in acute heat, hypoxia and the combination of heat and hypoxia and to determine whether prior acute exposure to these stressors improved cellular tolerance to a subsequent exercise bout in hypoxia 24 h later. METHODS: Twelve males (age 22 ± 4 years, height 1.77 ± 0.05 m, mass 79 ± 12.9 kg, VO(2) max 3.57 ± 0.7 L · min(-1)) completed four trials (30-min rest, 90-min cycling at 50% normoxic VO(2) max) in normothermic normoxia (NORM; 18°C, F(I)O(2) = 0.21), heat (HEAT; 40°C, 20% RH), hypoxia (HYP; F(I)O(2) = 0.14) or a combination of heat and hypoxia (COM; 40°C, 20% RH, F(I)O(2) = 0.14) separated by at least 7 days. Twenty-four hours after each trial, participants completed a hypoxic stress test (HST; 15-min rest, 60-min cycling at 50% normoxic VO(2) max, F(I)O(2) = 0.14). Monocyte heat shock protein 72 (mHSP72) was assessed immediately before and after each exercise bout. RESULTS: mHSP72 increased post exercise in NORM (107% ± 5.5%, p > 0.05), HYP (126% ± 16%, p < 0.01), HEAT (153% ± 14%, p < 0.01) and COM (161% ± 32%, p < 0.01). mHSP72 had returned to near-resting values 24 h after NORM (97% ± 8.6%) but was elevated after HEAT (130% ± 19%), HYP (118% ± 17%) and COM (131% ± 19%) (p < 0.05). mHSP72 increased from baseline after HST(NORM) (118% ± 12%, p < 0.05), but did not increase further in HST(HEAT), HST(HYP) and HST(COM). CONCLUSIONS: The prior induction of mHSP72 as a result of COM, HEAT and HYP attenuated further mHSP72 induction after HST and was indicative of conferred cellular tolerance

Journey to work:exploring difficulties, solutions and the impact of aging

A study was conducted in the UK, as part of the New Dynamics of Ageing Working Late project, of the journey to work among 1215 older workers (age groups 45-49, 50-55, 56-60 and 60 + ). The aim was to identify problems or concerns that they might have with their commute, strategies that have been adopted to address them, and the role that employers can play to assist them. Follow-up interviews with 36 employees identified many strategies for assisting with the problems of journeys to work, ranging from car share and using public transport to flexible working and working some days from home. Further interviews with a sample of 12 mainly larger companies showed that employers feel a responsibility for their workers’ commute, with some offering schemes to assist them, such as adjusting work shift timings to facilitate easier parking. The research suggests that the journey to work presents difficulties for a significant minority of those aged over 45, including issues with cost, stress, health, fatigue and journey time. It may be possible to reduce the impact of these difficulties on employee decisions to change jobs or retire by assisting them to adopt mitigating strategies. It does not appear that the likelihood of experiencing a problem with the journey to work increases as the employee approaches retirement; therefore, any mitigating strategy is likely to help employees of all ages. These strategies have been disseminated to a wider audience through an online resource at www.workinglate.org

‘‘Beet-ing’’ the Mountain: A Review of the Physiological and Performance Effects of Dietary Nitrate Supplementation at Simulated and Terrestrial Altitude

Exposure to altitude results in multiple physiological consequences. These include, but are not limited to, a reduced maximal oxygen consumption, drop in arterial oxygen saturation, and increase in muscle metabolic perturbations at a fixed sub-maximal work rate. Exercise capacity during fixed work rate or incremental exercise and time-trial performance are also impaired at altitude relative to sea-level. Recently, dietary nitrate (NO3-) supplementation has attracted considerable interest as a nutritional aid during altitude exposure. In this review, we summarise and critically evaluate the physiological and performance effects of dietary NO3- supplementation during exposure to simulated and terrestrial altitude. Previous investigations at simulated altitude indicate that NO3- supplementation may reduce the oxygen cost of exercise, elevate arterial and tissue oxygen saturation, improve muscle metabolic function, and enhance exercise capacity/ performance. Conversely, current evidence suggests that NO3- supplementation does not augment the training response at simulated altitude. Few studies have evaluated the effects of NO3- at terrestrial altitude. Current evidence indicates potential improvements in endothelial function at terrestrial altitude following NO3- supplementation. No effects of NO3- supplementation have been observed on oxygen consumption or arterial oxygen saturation at terrestrial altitude, although further research is warranted. Limitations of the present body of literature are discussed, and directions for future research are provided

Influence of dietary nitrate supplementation on local sweating and cutaneous vascular responses during exercise in a hot environment.

Purpose We investigated the influence of inorganic nitrate (NO−3) supplementation on local sweating and cutaneous vascular responses during exercise in hot conditions. Method Eight healthy, young subjects were assigned in a randomized, double-blind, crossover design to receive NO−3 -rich beetroot (BR) juice (140 mL/day, containing ~8 mmol of NO−3) and NO−3-depleted placebo (PL) juice (140 mL/day, containing ~0.003 mmol of NO−3) for 3 days. On day 3 of supplementation, subjects cycled at an intensity corresponding to 55% of V̇ O2max for 30 min in hot conditions (30 °C, 50% relative humidity). Chest and forearm sweat rate (SR) and skin blood flow (SkBF), were measured continuously. Cutaneous vascular conductance (CVC) was calculated by SkBF/mean arterial pressure (MAP). Results Prior to exercise, plasma NO− 3 (21±6 and 581±161 µM) and nitrite (NO− 2 , 87±28 and 336±156 nM) concentrations were higher after BR compared to PL supplementation (P≤0.011, n=6). Oesophageal, mean skin, and mean body temperatures during exercise were not different between conditions. In addition, BR supplementation did not affect SR, SkBF, and CVC during exercise. A lower MAP was found after 30 min of exercise following BR supplementation (112±6 and 103±6 mmHg for PL and BR, respectively, P=0.021). Conclusion These results suggest that inorganic NO− 3 supplementation, which increases the potential for O2-independent NO production, does not affect local sweating and cutaneous vascular responses, but attenuates blood pressure in young healthy subjects exercising in a hot environment

Cross Adaptation - Heat and Cold Adaptation to Improve Physiological and Cellular Responses to Hypoxia

To prepare for extremes of heat, cold or low partial pressures of O2, humans can undertake a period of acclimation or acclimatization to induce environment specific adaptations e.g. heat acclimation (HA), cold acclimation (CA), or altitude training. Whilst these strategies are effective, they are not always feasible, due to logistical impracticalities. Cross adaptation is a term used to describe the phenomenon whereby alternative environmental interventions e.g. HA, or CA, may be a beneficial alternative to altitude interventions, providing physiological stress and inducing adaptations observable at altitude. HA can attenuate physiological strain at rest and during moderate intensity exercise at altitude via adaptations allied to improved oxygen delivery to metabolically active tissue, likely following increases in plasma volume and reductions in body temperature. CA appears to improve physiological responses to altitude by attenuating the autonomic response to altitude. While no cross acclimation-derived exercise performance/capacity data have been measured following CA, post-HA improvements in performance underpinned by aerobic metabolism, and therefore dependent on oxygen delivery at altitude, are likely. At a cellular level, heat shock protein responses to altitude are attenuated by prior HA suggesting that an attenuation of the cellular stress response and therefore a reduced disruption to homeostasis at altitude has occurred. This process is known as cross tolerance. The effects of CA on markers of cross tolerance is an area requiring further investigation. Because much of the evidence relating to cross adaptation to altitude has examined the benefits at moderate to high altitudes, future research examining responses at lower altitudes should be conducted given that these environments are more frequently visited by athletes and workers. Mechanistic work to identify the specific physiological and cellular pathways responsible for cross adaptation between heat and altitude, and between cold and altitude, is warranted, as is exploration of benefits across different populations and physical activity profiles

PRIOR SARS-COV-2 INFECTION DOES NOT INCREASE RISK OF EXERTIONAL HEAT STROKE OR CAUSE DETRIMENTAL CHANGES IN PLASMA CYTOKINES

Rachel Kowis, Rachael Badeau, Matthew Kuennen. High Point University, High Point, NC. Background. SARS-CoV-2 is a viral infection that can cause systemic inflammation with fever symptoms and impaired respiration. Data from animal models suggest that some forms of viral infection can increase risk for exertional heatstroke (EHS), possibly via reductions in the cellular stress response that lead to impaired stress tolerance.Purpose. To determine if persons with prior clinical diagnosis of SARS-CoV-2 infection exhibit any differences in thermoregulatory or cardiopulmonary responses to 60min of cycling exercise in hot, dry ambient conditions. Methods. Nine participants (Age: 22 ± 2 years, Stature: 1.74 ± 0.02 m, Mass: 71.3 ± 3.9 kg, VO2max: 46 ± 2 mL-1kg lean body mass-1.min-1) completed 1hr of cycling exercise in an environmental chamber (35°C / 35% RH) at an intensity that elicited 9.0 W/kg of metabolic heat production. Four participants had been previously diagnosed with SARS-CoV-2, and the other five participants served as the Control group. Heart rate (HR), esophageal temperature (Tc), mean body temperature (Tb), physiological strain index (PSI), minute ventilation (VE), and oxygen consumption (VO2) were examined throughout exercise. Interleukin 1 Receptor Antagonist (IL-1RA) and Interleukin 6 (IL-6) were assayed from plasma samples that were collected before (Pre), after (Post), and 1h after (1-Post) exercise. Differences between group data were determined with Two-Way RM-ANOVA with Tukey Post Hocs. Results: As compared to the Control group, persons with prior SARS-CoV-2 infection did not exhibit greater elevations in HR (84 ± 4% of HRmax vs 87 ± 2% of HRmax), Tc (1.4 ± 0.3 °C vs 1.1 ± 0.2 °C), Tb (1.2 ± 0.3 °C vs1.1 ± 0.2 °C), PSI (6.9 ± 1.0 vs 6.7 ± 0.6), VE (38.8 ± 4.3 L/min vs 40.5 ± 0.3 L/min) or VO2 (23.8 ± 1.1 ml/kg/min vs 21.0 ± 1.4 ml/kg/min) during 1hr of cycling exercise at a fixed rate of heat production in hot/dry ambient conditions [all P \u3e 0.05]. There were no differences in plasma IL-1RA between the two groups at any time-point [all P \u3e 0.05]. Despite having similar plasma IL-6 concentrations at baseline (0.5 ± 0.2 pg/ml vs 0.6 ± 0.3 pg/ml), the increase in IL-6 post-exercise was more than two-fold greater in the Control group (5.9 ±1.6 pg/ml vs 2.8 ± 0.6 pg/ml; P = 0.04). Conclusions. As compared to Control, we see no evidence of greater thermal or cardiovascular strain during 1hr of exertional heat stress in persons with prior SARS-CoV-2 infection. We also see no difference between groups in plasma IL-RA (which is anti-inflammatory), whereas the plasma IL-6 response to exercise appears to be diminished in persons with prior SARS-CoV-2 infection. While the exact physiologic relevance of this change remains to be determined, present study data do not provide any evidence of an adverse response to exertional heat stress in persons with prior SARS-CoV-2 infection