Effect of Exercise Training and +Gz Acceleration Training on Men

Countermeasures for reduction in work capacity (maximal oxygen uptake and strength) during spaceflight and enhanced orthostatic intolerance during re-entry, landing and egress from the return vehicle are continuing problems. The purpose for this study was to test the hypothesis that passive-acceleration training; supine, interval, exercise plus acceleration training and exercise combined with acceleration training would improve orthostatic tolerance in ambulatory men; and that addition of the aerobic exercise conditioning would not alter this improved tolerance from that of passive-acceleration training. Seven men (24-38 yr) underwent "Passive" training on the Ames human-powered centrifuge (HPC) for 30 min, "Exercise" training on the cycle ergometer with constant +Gz acceleration; and "Combined" exercise training at 40% to 90% of the HPC +Gz(max) exercise level. Maximal supine exercise loads increased significant (P<0.05) by 8.3% (Passive), 12.6% (Exercise), and by 15.4% (Combined) after training, but their post-training maximal oxygen uptakes and maximal heart rates were unchanged. Maximal time to fatigue (endurance) was unchanged with Passive was increased (P<0.05) with Exercise and Combined training. Thus, the exercise in the Exercise and Combined training Phases resulted in greater maximal loads and endurance without effect on maximal oxygen uptake or heart rate. There was a 4% to 6% increase (P<0.05) in all four quadriceps muscle volumes (right and left) after post-Combined training. Resting pre-tilt heart rate was elevated by 12.9% (P<0.05) only after Passive training suggesting that the exercise training attenuated the HR response. Plasma volume (% Delta) was uniformly decreased by 8% to 14% (P<0.05) at tilt-tolerance pre- vs. post-training indicating essentially no effect of training on the level of hypovolemia. Post-training tilt-tolerance time and heart rate were increased (P<0.05) only with Passive training by 37.8% and by 29.1%, respectively. Thus, addition of exercise training appeared to attenuate the increased Passive tilt-tolerance

Prevalence of self-reported polycystic ovary syndrome and profiles of health among women of different generations: a cross sectional study

Published 6 September 2019Objective: Although polycystic ovary syndrome (PCOS) is considered a lifelong disorder, very little is understood about the diagnosis and impact of this condition in women outside of the peak reproductive years. We examined the frequency of diagnosed PCOS and concurrent health conditions in women across the lifespan. Methods: Data were analysed from 1509 women aged 15–95 years participating in a cross-sectional, face-to-face population survey in South Australia, 2015. We assessed the prevalence of PCOS in 10-year age groups and the frequency of comorbidities in women with and without PCOS subgrouped by age (< 45, ≥ 45 years). The main outcome measures were Diagnosed PCOS and other chronic conditions; lifestyle factors. Logistic regression analyses determined the risk of comorbidities in women with PCOS adjusting for age and BMI. Results: Overall prevalence of PCOS was 5.6% (95% confidence interval (CI) 4.6–6.9%), peaking in the 35–44 year age group (9.1%), and lowest in those aged 15–24 (4.1%) or ≥ 65 (3.7%) years. Women with PCOS and aged < 45 years were more likely to report diabetes (16.7% vs. 3.8%), cardiovascular disease (15.5% vs. 7.2%) and arthritis (15.5% vs. 7.2%) than their peers; these differences were diminished in the ≥ 45 year age group. The odds of diabetes and cardiovascular disease were more than doubled among women with PCOS (adjOR 2.23, 95% CI 1.49–4.31; adjOR 3.18, 95% CI 1.31–7.68). Conclusion: PCOS is underdiagnosed in young and post-menopausal women. Diabetes and cardiovascular disease are key comorbidities requiring greater attention in younger women with PCOS.Jodie C. Avery, Lisa J. Moran, Vivienne Moore, Renae C. Fernandez, Melissa Whitrow, Nigel Stocks, Tiffany K. Gill, Michael Musker, Michael Davies, Alice Rumbol

Compartmental changes in the body-fluid contributions to the plasma volume restoration during recovery from dehydration following heat acclimation

Meeting abstract

Whole-body fluid distribution in humans during dehydration and recovery, before and after humid-heat acclimation induced using controlled hyperthermia

Aim This experiment was designed to test the hypothesis that the plasma volume is not selectively defended during exercise- and heat-induced dehydration following humid-heat acclimation. Methods Eight physically active males were heat acclimated (39.8 °C, relative humidity 59.2%) using 17 days of controlled hyperthermia (core temperature: 38.5 °C). Inter-compartmental fluid losses and movements were tracked (radioisotopes and Evans blue dye) during progressive dehydration (cycling) in these same conditions and also during a resting recovery without fluid replacement (28 °C), before (day 1), during (day 8) and after heat acclimation (day 22). Results On days 8 and 22, there were significant increases in total body water, interstitial fluid and plasma volume (P \u3c 0.05), but the intracellular compartments did not change (P \u3e 0.05). The baseline plasma volume remained expanded throughout: 43.4 [±2.6 (day 1)], 49.1 [±2.4 (day 8); P \u3c 0.05] and 48.9 mL kg−1 [±3.0 (day 22); P \u3c 0.05]. During progressive dehydration, plasma reductions of 9.0% (±0.9: day 1), 12.4% (±1.6: day 8) and 13.6% (±1.2: day 22) were observed, with day 8 and 22 losses significantly exceeding day 1 (P \u3c 0.05). During recovery, plasma volume restoration commenced, with the intracellular fluid contribution becoming more pronounced as acclimation progressed. Conclusion It is concluded that the plasma volume was not defended more vigorously following humid-heat acclimation. Indeed, a greater fluid loss may well underlie the mechanisms for enhancing plasma volume recovery when heat acclimation is induced using the controlled-hyperthermia technique

Thermal protective clothing and cardiovascular function

While the primary purpose of thennal protective uniforms is to minimise heat loading from hostile working environments, such uniforms also add to the physiological load by increasing metabolic rate, and limiting evaporative heat dissipation (I). Before one can provide physiological specifications for the design of thennal protective garments, one requires a thorough understanding ofthe physiological effects of wearing such unifonns. However, research in this area is dominated by field studies, with few cardiovascular variables being investigated. These field studies, while important, often bypass clothing trials under controlled laboratory conditions. As a consequence, very little is known about the cardiac output, skin blood flow orplasma volume responses associated with wearing thermal protective clothing. Therefore, weundertook a laboratorybased project to explore the mechanisms underlying the cardiovascular strain accompanying the use of thermal protective ensembles, relative to the unclothed state, during fatiguing exercise. We hypothesised that subjects would experience greater cardiovascular strain when wearing such clothing, and that this would limit their ability to perform maximal exercise