Heat Stress but Not Capsaicin Application Alleviates the Hypertensive Response to Isometric Exercise

Heat stress and cutaneous capsaicin application act independently to reduce mean arterial blood pressure (MAP) at rest. The present study investigated whether a mixed intervention might alleviate to a greater extent the hypertensive response to isometric exercise. An end-exercise systolic blood pressure (SBP) lower than 215 mmHg or higher than 220 mmHg was set for the inclusion in the group observed with typical (CON, n = 9) or hypertensive (HRE, n = 8) response to dynamic exercise, respectively. The participants performed four trials held in thermoneutral (TN:23 °C) or hot (HT:33 °C) conditions with capsaicin (CA:4.8 mg·patch−1) or placebo (PL) patches (12 × 18 cm2) applied to their two quadriceps, left pectoralis major and left scapula. The trials comprised: a 5 min baseline period preceding patch application, a 30 min rest period and a 5 min isometric handgrip exercise (20% maximal voluntary contraction, 10.1 ± 1.9 kg). Thermoregulatory and cardiovascular data were analyzed using mixed three-way ANOVA. End-resting MAP and pain sensation were higher in PL-TN (p = 0.008) and CA-HT (p = 0.012), respectively. End-exercise SBP tended to be higher in HRE individuals across environments (p = 0.10). Total peripheral resistance and MAP remained lower in HT across groups (p < 0.05). Despite the alleviating effect of the heat stressor, an augmented burning sensation-induced peripheral vasoconstriction might have blunted the pressure-lowering action of capsaicin

THE ROLE OF ACTIVE MUSCLE MASS ON EXERCISE-INDUCED CARDIOVASCULAR DRIFT

The purpose of this study was to examine the role of active muscle mass on cardiovascular drift (CVdrift) during prolonged exercise. Twelve subjects with peak oxygen uptake (VO2peak) of 3.52 ± 0.52 L·min-1 (mean ± SD) cycled for 55 min with 80 revolutions per minute with either two legs (2-legged) or one leg (1-legged). Oxygen uptake was at 60% of VO2peak throughout the 2-legged trial and at half of this value in 1- legged condition. Cardiac output (CO-CO2 rebreathing), heart rate (HR) and quadriceps integrated electromyographic activity (iEMG) were higher (p < 0.01) during 2-legged than 1- legged exercise. Changes in stroke volume from 20 to 50 min of exercise were greater in 2-legged than in 1-legged (∆SV: -20.8 ± 0.8 vs. -13.3 ± 1.3 ml·beat-1, p < 0.05). Similarly, changes in heart rate (∆HR) were +18.5 ± 0.8 and +10.7 ± 1.0 beats·min-1, in 2-legged and 1-legged, respectively (p < 0.01). Calculated blood volume changes declined significantly in 2-legged exercise (∆BV: -4.25 ± 0.43%, p < 0.05). Sympathetic activation as indicated by the ratio of low and high frequency in spectral analysis of HR (LF HF-1 ratio) was higher in 2-legged than in 1- legged trial (p < 0.05). At the end of exercise, CO had a tendency to decrease from 20th min in 2-legged (changes in CO = -0.92 ± 0.3 L·min-1, p = 0.07), whereas it was maintained in 1- legged cycling (∆CO = -0.15 ± 0.2 L·min-1, p = 0.86). Multiple regression analysis showed that HR rise and blood volume decline were predictors of SV drop whereas heart rate increase was explained by rectal temperature and magnitude of muscle mass activation, as indicated by iEMG (p < 0.05) in 2-legged cycling. In conclusion, apart from the well-known factors of thermal status and blood volume decline, it seems that muscle mass involved plays also a role on the development of CVdrif

Physiological responses of anemic women to exercise under hypoxic conditions

When combining two conditions of reduced oxygen availability, anemia and hypoxia, human physiological responses are highly challenged to maintain arterial oxygen delivery, especially during whole-body exercise. The aim of this study was to compare the cardiorespiratory responses of mildly anemic women with those of healthy controls, while cycling in normobaric hypoxia. Two groups of young females were matched for age, weight, height, and involvement in physical activity, one with normal hemoglobin, hematocrit, and ferritin levels and another suffering from mild iron deficiency anemia (10 &lt; (Hb) &lt; 12 g/dL, 34 &lt; Hct &lt; 37%, ferritin &lt; 15 μg/L). They cycled to exhaustion under normoxia and hypoxia (FIO2 0.21 and 0.14), and their physiological responses were compared at 40, 80, and 100% VO2max of the specific condition. The two groups differed (p &lt; 0.05) mainly at the higher exercise intensities; the anemic participants exhibited similar heart rate but lower oxygen pulse than their control counterparts, as well as a larger drop in maximal oxygen uptake. However, they sustained maximal effort by employing the anaerobic metabolism to a larger extent, which stimulated a greater ventilatory response. It appears that iron deficiency anemia of mild severity, which is commonly observed in young athletic females, impacts physiological responses during whole-body exercise in the presence of moderate hypoxia.QCR 20230412</p

The Effect of Chronic Dietary Protein Manipulation on Amino Acids’ Profile and Position Sense in the Elderly Suffering from Type 2 Diabetes Mellitus

Dietary protein with adequate essential amino acids effectively stimulates protein synthesis and improves muscle mass. Musculoskeletal disorders in lower or upper limbs are not uncommon among patients with type II diabetes mellitus (T2DM). Therefore, this study primarily examines the effects of chronic dietary protein manipulation on amino acids’ profile and position sense in the elderly suffering from T2DM. A total of 26 individuals suffering from non-insulin-dependent T2DM (age > 55 years old) participated in a 12 week nutritional intervention. The subjects were randomly assigned and the control group received 0.8–1.0 g protein/kg/day, while the intervention group received 1.2–1.5 g protein/kg/day. Lean body mass, muscle strength, and position sense were assessed at baseline, as well as at the 6th and 12th week of the intervention. Only in the intervention group, the essential amino acids intake met the current nutritional recommendations (p p p p p = 0.072). In the present investigation, it was revealed that the higher protein intake in the intervention group seemed to have positive effects on muscle strength and nearly positive effects on position sense