Jefferson Lima de Santana

Active postural transitions impose rapid orthostatic stress that requires coordinated cardiovascular compensation. Whether the magnitude and timing of these responses differ by gravitational load, age, and sex during common daily movements remains unclear. This study compared short-term cardiovascular regulation during sit-to-stand (lower gravitational load) and lie-to-stand (higher gravitational load) transitions in younger and older adults. Fifty-six healthy participants (younger and older females and males; n = 14 per group) completed both transitions in a randomized, counterbalanced design. Beat-to-beat blood pressure and hemodynamic responses were assessed at baseline, immediately on standing, and across four predefined compensatory phases. General linear models examined the effects of condition, age, sex, and age-sex interactions, with cardiovascular medication included as a covariate. Lie-to-stand elicited larger immediate reductions in systolic, diastolic, and mean arterial pressure, alongside greater heart rate increases, compared with sit-to-stand (all p < 0.001). Older adults demonstrated larger drops in blood pressure and systemic vascular resistance, and blunted heart rate and cardiac output responses, particularly under higher gravitational load. In contrast, older adults maintained relatively higher stroke volume during lie-to-stand, suggesting greater reliance on mechanical compensation. Sex-related differences were condition-specific: younger males exhibited higher cardiac output during sit-to-stand, while older females showed higher late-phase mean arterial pressure and vascular resistance during lie-to-stand. These findings indicate that gravitational load strongly influences short-term cardiovascular compensation during active standing and amplifies age-related differences. Sit-to-stand and lie-to-stand transitions provide complementary information, highlighting the importance of considering transition type when evaluating orthostatic cardiovascular regulation.

Background: Frailty is a multifactorial condition that significantly impacts older adults’ health and independence, which can be mitigated through training. This study examined the effects of a 12-week progressive strength training (PST) program on frailty status and short-term autonomic compensatory responses during postural transitions. Methods: Eight older adults (60–79 years) classified as pre-frail or frail according to the frailty index (FI) participated in a 12-week PST program. Time and frequency-domain heart rate variability (HRV) in the supine position, cardiac parasympathetic modulation (CPM) determined from the HR 30:15 ratio (longest RR interval around the 30th heartbeat divided by the shortest RR interval around the 15th heartbeat after standing), and cardiac baroreceptor gain (CBG) assessed as the ratio of heart rate change to systolic blood pressure drop (ΔHR/ΔSBP) at 30, 60, 180, and 420 s after standing were assessed at pre-test, 8 weeks and 12 weeks (autonomic function outcomes). Physical activity levels (PAL), handgrip strength (HGS), and gait speed (GS) were assessed, and orthostatic intolerance (OI) symptoms were self-reported at pre-test, 8 weeks, and 12 weeks. Results: After 12 weeks of PST, FI scores decreased from 0.18 to 0.04 (78% reduction). PAL, HGS, and GS improved by 152%, 13%, and 11%, respectively. Three of eight participants reported OI symptoms at pre-test, with no reported symptoms at week 12. Despite this, PST did not enhance short-term autonomic responses. Conclusions: PST counteracted frailty and improved physical and muscular function but did not enhance indices of short-term autonomic regulation in frail older people.

Intensive care unit-acquired weakness (ICU-AW) research focuses predominantly on intrinsic muscle pathology rather than integrated systemic interactions, which are commonly studied in exercise science. Peak oxygen uptake (V˙O2peak), V˙O2 on/off kinetics, and skeletal muscle oxygenation provide a quantitative evaluation of exercise capacity and are infrequently measured in intensive care unit (ICU) survivors. Routine cardiopulmonary exercise test (CPET) research separates V˙O2peak and V˙O2 kinetics assessments into multiple sessions. Yet, a combined experimental approach may enhance diagnosis, follow-up retention, and mechanistic insight for patients with ICU-AW. This prospective cross-sectional observational study aims to develop a standardized, single-session CPET protocol for combined assessment of V˙O2peak, V˙O2 kinetics, and skeletal muscle microvascular oxygenation in ICU survivors, enabling quantitative and integrated assessment of ICU-AW. Adults mechanically ventilated for ≥7 days will be recruited to participate 6 months post-ICU discharge in a modified CPET exercise session on an upright cycle ergometer. The proposed standardization will involve (1) the estimation of V˙O2peak using a priori formulas with a V˙O2peak correction factor for the ICU population, (2) V˙O2 on-kinetics (constant work rate) targeting relative 30% V˙O2reserve, (3) an incremental ramp exercise based on self-reported functional status, and (4) a 10-minute recovery to quantify V˙O2 off-kinetics. In addition, near-infrared spectroscopy will be placed on the vastus lateralis muscle to simultaneously collect tissue saturation index and deoxyhemoglobin during each phase of the protocol. Recruitment is anticipated to begin in June 2026 and is expected to be completed in 2029/2030. The anticipated sample size will be approximately 48 participants based on the feasibility of recruiting 1 participant per month and a sample size calculation based on Bland-Altman limits of agreement between predicted and measured V˙O2peak. The intensive care unit combined assessment of cardiorespiratory exercise (ICU-CARE) CPET protocol will enable the quantitative evaluation of V˙O2peak, V˙O2 on/off kinetics, and local microvascular skeletal muscle oxygenation during a single exercise session, facilitating the integrated physiological study of ICU-AW.

Background: Frailty is a multifactorial condition that significantly impacts older adults' health and independence, which can be mitigated through training. This study examined the effects of a 12-week progressive strength training (PST) program on frailty status and short-term autonomic compensatory responses during postural transitions. Methods: Eight older adults (60-79 years) classified as pre-frail or frail according to the frailty index (FI) participated in a 12-week PST program. Time and frequency-domain heart rate variability (HRV) in the supine position, cardiac parasympathetic modulation (CPM) determined from the HR 30:15 ratio (longest RR interval around the 30th heartbeat divided by the shortest RR interval around the 15th heartbeat after standing), and cardiac baroreceptor gain (CBG) assessed as the ratio of heart rate change to systolic blood pressure drop (ΔHR/ΔSBP) at 30, 60, 180, and 420 seconds after standing were assessed at pre-test, 8 weeks and 12 weeks (autonomic function outcomes). Physical activity levels (PAL), handgrip strength (HGS), and gait speed (GS) were assessed, and orthostatic intolerance (OI) symptoms were self-reported at pre-test, 8 weeks, and 12 weeks. Results: After 12 weeks of PST, FI scores decreased from 0.18 to 0.04 (78% reduction). PAL, HGS, and GS improved by 152%, 13%, and 11%, respectively. Three of eight participants reported OI symptoms at pre-test, with no reported symptoms at week 12. Despite this, PST did not enhance short-term autonomic responses. Conclusion: PST counteracted frailty and improved physical and muscular function but did not enhance indices of short-term autonomic regulation in frail older people.

Background. Frailty is a multifactorial condition that significantly impacts older adults' health and independence, which can be mitigated through training. This study examined the effects of a 12-week progressive strength training (PST) program on frailty status and short-term autonomic compensatory responses during postural transitions. Methods: Eight older adults (60-79 years) classified as pre-frail or frail according to the frailty index (FI) participated in a 12-week PST program. Time and frequency-domain heart rate varia-bility (HRV) in the supine position, cardiac parasympathetic modulation (CPM) deter-mined from the HR 30:15 ratio (longest RR interval around the 30th heartbeat divided by the shortest RR interval around the 15th heartbeat after standing), and cardiac baroreceptor gain (CBG) assessed as the ratio of heart rate change to systolic blood pressure drop (ΔHR/ΔSBP) at 30, 60, 180, and 420 seconds after standing were assessed at pre-test, 8 weeks and 12 weeks (autonomic function outcomes). The level of physical activity (LPA), handgrip strength (HGS), and gait speed (GS) were assessed, and orthostatic intolerance (OI) symptoms were self-reported at pre-test, 8 weeks and 12 weeks. Results: After 12 weeks of PST, FI scores decreased from 0.18 to 0.04 (78% reduction). LPA, HGS, and GS improved by 152%, 13%, and 11%, respectively. Three of eight participants reported OI symptoms at pre-test, with no reported symptoms at week 12. Despite this, PST did not enhance short-term autonomic responses. Conclusion: PST counteracted frailty and im-proved physical and muscular function but did not enhance indices of short-term auto-nomic regulation in frail older people.

Background: The cardiovascular system of older adults is significantly impacted by aging, contributing to blood pressure (BP) dysregulation, particularly during postural transitions. This study compared the short-term cardiovascular compensatory responses of younger adults (YA) and older adults (OA) during sit-to-stand and lie-to-stand. Methods: Participants underwent two active standing orthostatic stress tests, involving 5 min of sitting or 10 min of lying, followed by up to 7 min of standing. Beat-to-beat cardiovascular parameters were assessed using a Finometer (Finapres Medical Systems). Systolic (SBP), diastolic (DBP), mean arterial pressure (MAP), cardiac output (CO), stroke volume (SV), systemic vascular resistance (SVR), and HR were measured at baseline, immediately on standing, and throughout four specific phases after standing: phase 1 (0–30 s), phase 2 (30–60 s), phase 3 (60–80 s), and phase 4 (300–420 s). CO-SVR matching was evaluated to assess BP regulation timing. Results: Compared to YA, OA exhibited higher SBP, DBP, MAP, and SVR but lower HR, CO, and SV at baseline. Immediately on standing, OA experienced a greater drop in SBP, DBP, MAP, and SVR, blunted HR, reduced CO, and higher SV. The short-term compensatory responses were delayed (30–60 s), particularly in lie-to-stand, due to a transient CO and SVR mismatch observed in phase 1 and subsequent BP stabilization from phases 2–4. Conclusions: OA exhibited short-term compensatory cardiovascular dysregulation, particularly during the transition from a lying to a standing position.

Background: As we age, our autonomic function declines, resulting in altered autonomic balance during postural transitions. These changes can affect the dynamic interplay between sympathetic and parasympathetic modulation, compromising short-term compensatory responses to active standing. Objectives: This study aimed to compare heart rate variability (HRV) at baseline, cardiac parasympathetic modulation (CPM), and cardiac baroreflex gain (CRG) between younger adults (YA) and older adults (OA) following active standing orthostatic stress. A secondary objective was to analyze the incidence of orthostatic intolerance (OI) symptoms. Methods: Participants (n = 76) completed sit-to-stand and lie-to-stand maneuvers with continuous beat-to-beat blood pressure and heart rate (HR, electrocardiogram). HRV at baseline was analyzed in both time and frequency domains. CPM was measured by the HR 30:15 ratio on standing. CBG was determined as the ratio of HR and SBP changes (ΔHR/ΔSBP) at specific phase time points (30 s, 60 s, 180 s, and 420 s). Results: At baseline, OA showed reduced Standard Deviation of RR intervals (SDRR), Root Mean Square of Successive Differences (RMSSD), low-frequency (LF), and high-frequency (HF) power, and elevated LF/HF ratio (all p < 0.05), indicating a shift toward sympathetic dominance. During active standing orthostatic stress, OA demonstrated a lower HR30:15 ratio and CBG in later phases (phases 2–4) (all p < 0.05). Also, OA reported more symptoms (14%) of OI than YA (0%) (p = 0.041). Conclusions: These findings indicate that older adults have impaired autonomic function characterized by reduced HRV, CPM and CBG responses. These impairments lead to diminished autonomic regulation under active-standing orthostatic stress and a higher incidence of OI symptoms.

Background: The cardiovascular system of older adults is significantly impacted by ageing, contributing to blood pressure (BP) dysregulation, particularly during postural transitions. This study compared short-term cardiovascular compensatory responses of younger adults (YA) and older adults (OA) during sit-to-stand and lie-to-stand. Methods: Participants underwent two active standing orthostatic stress tests, involving 5 minutes of sitting or 10 minutes of lying, followed by up to 7 minutes of standing. Beat-to-beat cardiovascular parameters were assessed using a Finometer (Finapres Medical Systems). Systolic (SBP), diastolic (DBP), mean arterial pressure (MAP), cardiac output (CO), stroke volume (SV), systemic vascular resistance (SVR), and HR were measured at baseline, immediately on standing, and throughout four specific phases after standing: phase 1 (0-30s), phase 2 (30-60s), phase 3 (60-80s), and phase 4 (300-420s). CO-SVR matching was evaluated to assess BP regulation timing. Results: Compared to YA, OA exhibited higher SBP, DBP, MAP, and SVR but lower HR, CO, and SV at baseline. Immediately on standing, OA experienced a greater drop in SBP, DBP, MAP, and SVR, blunted HR, reduced CO, and higher SV. The short-term compensatory responses were delayed (30-60s), particularly in lie-to-stand, due to a transient CO and SVR mismatch observed in phase 1 and subsequent BP stabilization from phases 2-4. Conclusion: OA exhibited short-term compensatory cardiovascular dysregulation, particularly during the transition from a lying to a standing position.

As we age, our autonomic function declines, resulting in altered autonomic balance during postural transitions. These changes can affect the dynamic interplay between sympathetic and parasympathetic modulation, compromising short-term compensatory responses to active standing. This study aimed to compare heart rate variability (HRV) at baseline, cardiac parasympathetic modulation (CPM), and cardiac baroreflex gain (CRG) between younger adults (YA) and older adults (OA) following active standing orthostatic stress. A secondary objective was to analyze the incidence of orthostatic intolerance (OI) symptoms. Participants completed sit-to-stand and lie-to-stand maneuvers with continuous beat-to-beat blood pressure and heart rate (HR, electrocardiogram). HRV at baseline was analyzed in both time and frequency domains. CPM was measured by the ratio between HR at the 30th beat and the 15th beat (HR 30:15) on standing. CBG was determined as the ratio of HR and SBP changes (ΔHR/ΔSBP) at specific phase time points (30s, 60s, 180s, and 420s). At baseline, OA exhibited reduced Standard Deviation of RR intervals (SDRR), Root Mean Square of Successive Differences (RMSSD), low-frequency (LF), and high-frequency (HF) power, and elevated LF/HF ratio, indicating a shift toward sympathetic dominance. During active standing orthostatic stress, OA demonstrated higher CPM and lower CBG in later phases (phases 2-4). Also, OA reported more symptoms (14%) of OI than YA (0%). In conclusion, these findings indicate that older adults have impaired autonomic function characterized by reduced HRV, higher CPM, and lower CBG. These impairments lead to diminished autonomic regulation under active-standing orthostatic stress and a higher incidence of OI symptoms.

Background: Paralympic powerlifting (PP) is performed on a bench press, aiming to lift as much weight as possible in a single repetition. Purpose: To evaluate thermal asymmetry and dynamic force parameters with 45 and 80% 1 Repetition Maximum (1 RM) in PP athletes. Methods: Twelve elite PP male athletes were evaluated before and after a training session regarding skin temperature (thermography) and dynamic force indicators (Average Propulsive Velocity-MPV, Maximum Velocity-VMax, and Power). The training consisted of five series of five repetitions (5 × 5) with 80% 1 RM. The force indicators and dynamics before and after (45% 1 RM) were evaluated in series “1” and “5” with 80% 1 RM. Results: The temperature did not present asymmetry, and there were differences between the moment before and after. In MPV, Vmax, and Power, with 45% 1 RM, there were differences both in asymmetry and in moments (p < 0.005). With 80% 1 RM, asymmetry was observed, but no differences between moments (p < 0.005). Conclusion: No thermal asymmetry was observed. There were reductions in MVP and VMax at 45 and 80% 1 RM but without significant differences between time points (before and after). However, there was asymmetry in the moments before and after within a safety standard, where Paralympic powerlifting was safe in terms of asymmetries.