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1.
Blood Cancer Discov ; 2024 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-38953781

RESUMO

This real-world prospective observational study across 21 Italian centers (CART-SIE) compares axicabtagene ciloleucel (axi-cel) and tisagenlecleucel (tisa-cel) outcomes in 485 relapsed-refractory large B-cell lymphoma patients with baseline characteristics matched by Stabilized Inverse Propensity-Score Weighting. Axi-cel versus tisa-cel had higher all-grade cytokine release syndrome (78.6% vs 89.3%, p=0.0017) and neurotoxicity (9.9% vs 32.2%, p<0.0001), but also superior progression-free survival (PFS) at one year (46.5% vs 34.1%, p=0.0009). Even among patients who failed bridging therapy, axi-cel PFS was superior to tisa-cel (37.5% vs 22.7%, p=0.0059). Differences in overall survival (OS) and high-grade immune toxicities were not significant. The CAR-HEMATOTOX score not only predicted hematologic toxicity but also 1-year survival outcomes (51.5% in CAR-HEMATOTOX high vs. 77.2% in CAR-HEMATOTOX low, p<0.0001). Twenty patients developed second primary malignancies, including two cases of T-cell neoplasms. These findings enable more informed selection of anti-CD19 CAR T-cell therapy balancing bridging, safety and efficacy considerations for individual patients.

2.
Cereb Cortex ; 34(3)2024 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-38494417

RESUMO

During NREM sleep, hippocampal sharp-wave ripple (SWR) events are thought to stabilize memory traces for long-term storage in downstream neocortical structures. Within the neocortex, a set of distributed networks organized around retrosplenial cortex (RS-network) interact preferentially with the hippocampus purportedly to consolidate those traces. Transient bouts of slow oscillations and sleep spindles in this RS-network are often observed around SWRs, suggesting that these two activities are related and that their interplay possibly contributes to memory consolidation. To investigate how SWRs interact with the RS-network and spindles, we combined cortical wide-field voltage imaging, Electrocorticography, and hippocampal LFP recordings in anesthetized and sleeping mice. Here, we show that, during SWR, "up-states" and spindles reliably co-occur in a cortical subnetwork centered around the retrosplenial cortex. Furthermore, retrosplenial transient activations and spindles predict slow gamma oscillations in CA1 during SWRs. Together, our results suggest that retrosplenial-hippocampal interaction may be a critical pathway of information exchange between the cortex and hippocampus.


Assuntos
Neocórtex , Sono de Ondas Lentas , Camundongos , Animais , Giro do Cíngulo , Hipocampo , Sono
3.
Blood Adv ; 8(8): 1968-1980, 2024 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-38359407

RESUMO

ABSTRACT: CD19-directed chimeric antigen receptor (CAR) T cells can induce durable remissions in relapsed/refractory large B-cell lymphomas (R/R LBCLs), but 60% of patients do not respond or relapse. Biological mechanisms explaining lack of response are emerging, but they are largely unsuccessful in predicting disease response at the patient level. Additionally, to maximize the cost-effectiveness of CAR T-cell therapy, biomarkers able to predict response and survival before CAR T-cell manufacturing would be desirable. We performed transcriptomic and functional evaluations of leukapheresis products in 95 patients with R/R LBCL enrolled in a prospective observational study, to identify correlates of response and survival to tisagenlecleucel and axicabtagene ciloleucel. A signature composed of 4 myeloid genes expressed by T cells isolated from leukapheresis products is able to identify patients with a very short progression-free survival (PFS), highlighting the impact of monocytes in CAR T-cell therapy response. Accordingly, response and PFS were also negatively influenced by high circulating absolute monocyte counts at the time of leukapheresis. The combined evaluation of peripheral blood monocytes at the time of leukapheresis and the 4-gene signature represents a novel tool to identify patients with R/R LBCL at very high risk of progression after CAR T-cell therapy and could be used to plan trials evaluating CAR T cells vs other novel treatments or allogeneic CAR T cells. However, it also highlights the need to incorporate monocyte depletion strategies for better CAR T production.


Assuntos
Linfoma Difuso de Grandes Células B , Receptores de Antígenos Quiméricos , Humanos , Imunoterapia Adotiva/efeitos adversos , Receptores de Antígenos Quiméricos/genética , Monócitos , Leucaférese , Recidiva Local de Neoplasia , Linfoma Difuso de Grandes Células B/terapia , Antígenos CD19
4.
Cell Rep ; 42(9): 113015, 2023 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-37632747

RESUMO

The execution of cognitive functions requires coordinated circuit activity across different brain areas that involves the associated firing of neuronal assemblies. Here, we tested the circuit mechanism behind assembly interactions between the hippocampus and the medial prefrontal cortex (mPFC) of adult rats by recording neuronal populations during a rule-switching task. We identified functionally coupled CA1-mPFC cells that synchronized their activity beyond that expected from common spatial coding or oscillatory firing. When such cell pairs fired together, the mPFC cell strongly phase locked to CA1 theta oscillations and maintained consistent theta firing phases, independent of the theta timing of their CA1 counterpart. These functionally connected CA1-mPFC cells formed interconnected assemblies. While firing together with their CA1 assembly partners, mPFC cells fired along specific theta sequences. Our results suggest that upregulated theta oscillatory firing of mPFC cells can signal transient interactions with specific CA1 assemblies, thus enabling distributed computations.


Assuntos
Hipocampo , Ritmo Teta , Ratos , Animais , Hipocampo/fisiologia , Neurônios/fisiologia , Córtex Pré-Frontal/fisiologia
5.
Elife ; 122023 07 18.
Artigo em Inglês | MEDLINE | ID: mdl-37462671

RESUMO

Oscillations occurring simultaneously in a given area represent a physiological unit of brain states. They allow for temporal segmentation of spikes and support distinct behaviors. To establish how multiple oscillatory components co-vary simultaneously and influence neuronal firing during sleep and wakefulness in mice, we describe a multivariate analytical framework for constructing the state space of hippocampal oscillations. Examining the co-occurrence patterns of oscillations on the state space, across species, uncovered the presence of network constraints and distinct set of cross-frequency interactions during wakefulness compared to sleep. We demonstrated how the state space can be used as a canvas to map the neural firing and found that distinct neurons during navigation were tuned to different sets of simultaneously occurring oscillations during sleep. This multivariate analytical framework provides a window to move beyond classical bivariate pipelines for investigating oscillations and neuronal firing, thereby allowing to factor-in the complexity of oscillation-population interactions.


Assuntos
Hipocampo , Sono , Camundongos , Animais , Hipocampo/fisiologia , Sono/fisiologia , Neurônios/fisiologia , Encéfalo
6.
Blood Adv ; 7(19): 5996-6004, 2023 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-37450382

RESUMO

Infections are a major cause of morbidity and mortality during neutropenia after hematopoietic stem cell transplantation (HSCT). The use of a low-microbial protective diet (PD) in the peritransplantation period is a standard of care, although its efficacy has never been tested prospectively. We conducted a multicenter, randomized, noninferiority trial, enrolling all consecutive adult patients undergoing high-dose induction chemotherapy or HSCT with the objective to compare nonrestrictive diet (NRD) vs PD. Overall, 222 patients were enrolled, randomly assigned, and analyzed. One hundred seventy-five subjects (79%) received autologous HSCT (auto-HSCT), 41 (18%) received allogeneic HSCT (allo-HSCT), and 6 (3%) patients received high-dose induction chemotherapy. There was no significant difference in terms of incidence of grade ≥2 infections and death during neutropenia in the 2 arms. In multivariable analysis, only multiple myeloma diagnosis, fluoroquinolone prophylaxis, and the absence of mucositis were associated with a lower incidence of grade ≥2 infections. We did not report any significant variation in terms of hospitalization length, incidence of mucositis and gastrointestinal infections, body weight, and serum albumin variations in the 2 arms. In allo-HSCT recipients, the incidence of acute graft-versus-host disease grade ≥3 was similar. NRD was associated with higher patient-reported satisfaction. In conclusion, NRD is not inferior to a traditional PD during neutropenia after HSCT, and our results demonstrated that implementing a restrictive diet unnecessary burdens patients' quality of life. The clinical trial was registered prospectively in the clinical trial registry of the Istituto Nazionale dei Tumori of Milan as INT54/16.

8.
Cell Rep ; 42(2): 112022, 2023 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-36709427

RESUMO

Theta sequences and phase precession shape hippocampal activity and are considered key underpinnings of memory formation. Theta sequences are sweeps of spikes from multiple cells, tracing trajectories from past to future. Phase precession is the correlation between theta firing phase and animal position. Here, we reconsider these temporal processes in CA1 and the computational principles that they are thought to obey. We find stronger heterogeneity than previously described: we identify cells that do not phase precess but reliably express theta sequences. Other cells phase precess only when medium gamma (linked to entorhinal inputs) is strongest. The same cells express more sequences, but not precession, when slow gamma (linked to CA3 inputs) dominates. Moreover, sequences occur independently in distinct cell groups. Our results challenge the view that phase precession is the mechanism underlying the emergence of theta sequences, suggesting a role for CA1 cells in multiplexing diverse computational processes.


Assuntos
Células de Lugar , Camundongos , Animais , Potenciais de Ação , Ritmo Teta , Modelos Neurológicos , Hipocampo
9.
Proc Natl Acad Sci U S A ; 119(44): e2204959119, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36279469

RESUMO

Hippocampus-neocortex interactions during sleep are critical for memory processes: Hippocampally initiated replay contributes to memory consolidation in the neocortex and hippocampal sharp wave/ripples modulate cortical activity. Yet, the spatial and temporal patterns of this interaction are unknown. With voltage imaging, electrocorticography, and laminarly resolved hippocampal potentials, we characterized cortico-hippocampal signaling during anesthesia and nonrapid eye movement sleep. We observed neocortical activation transients, with statistics suggesting a quasi-critical regime, may be helpful for communication across remote brain areas. From activity transients, we identified, in a data-driven fashion, three functional networks. A network overlapping with the default mode network and centered on retrosplenial cortex was the most associated with hippocampal activity. Hippocampal slow gamma rhythms were strongly associated to neocortical transients, even more than ripples. In fact, neocortical activity predicted hippocampal slow gamma and followed ripples, suggesting that consolidation processes rely on bidirectional signaling between hippocampus and neocortex.


Assuntos
Consolidação da Memória , Neocórtex , Ritmo Gama , Hipocampo/fisiologia , Sono/fisiologia , Memória/fisiologia , Neocórtex/fisiologia
10.
Nat Rev Neurosci ; 23(10): 628-640, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-35970912

RESUMO

The spontaneous replay of patterns of activity related to past experiences and memories is a striking feature of brain activity, as is the coherent activation of sets of brain areas - particularly those comprising the default mode network (DMN) - during rest. We propose that these two phenomena are strongly intertwined and that their potential functions overlap. In the 'cascaded memory systems model' that we outline here, we hypothesize that the DMN forms the backbone for the propagation of replay, mediating interactions between the hippocampus and the neocortex that enable the consolidation of new memories. The DMN may also independently ignite replay cascades, which support reactivation of older memories or high-level semantic representations. We suggest that transient cortical activations, inducing long-range correlations across the neocortex, are a key mechanism supporting a hierarchy of representations that progresses from simple percepts to semantic representations of causes and, finally, to whole episodes.


Assuntos
Rede de Modo Padrão , Neocórtex , Hipocampo/fisiologia , Humanos , Neocórtex/fisiologia
11.
Clin Cancer Res ; 28(15): 3378-3386, 2022 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-35583610

RESUMO

PURPOSE: In clinical trials, the expansion and persistence of chimeric antigen receptor (CAR) T cells correlate with therapeutic efficacy. However, properties of CAR T cells that enable their in vivo proliferation have still to be consistently defined and the role of CAR T bag content has never been investigated in a real-life setting. EXPERIMENTAL DESIGN: Residual cells obtained after washing 61 anti-CD19 CAR T product bags were analyzed to identify tisagenlecleucel/Tisa-cel and axicabtagene ciloleucel/Axi-cel phenotypic features associated with postinfusion CAR T-cell in vivo expansion and with response and survival. RESULTS: While Tisa-cel was characterized by a significant enrichment in CAR+CD4+ T cells with central memory (P < 0.005) and effector (P < 0.005) phenotypes and lower rates of CAR+CD8+ with effector memory (P < 0.005) and naïve-like (P < 0.05) phenotypes as compared with Axi-cel, the two products displayed similar expansion kinetics. In vivo CAR T-cell expansion was influenced by the presence of CAR T with a CD8+ T central memory signature (P < 0.005) in both Tisa-cel and Axi-cel infusion products and was positively associated with response and progression-free survival (P < 0.05). CONCLUSIONS: Our data indicate that despite the great heterogeneity of Tisa-cel and Axi-cel products, the differentiation status of the infused cells mediates CAR T-cell in vivo proliferation that is necessary for antitumor response.


Assuntos
Linfoma Difuso de Grandes Células B , Receptores de Antígenos Quiméricos , Antígenos CD19/uso terapêutico , Humanos , Imunoterapia Adotiva , Linfoma Difuso de Grandes Células B/patologia , Fenótipo , Receptores de Antígenos Quiméricos/genética , Linfócitos T
12.
Artigo em Inglês | MEDLINE | ID: mdl-35457430

RESUMO

The aim of this study was to investigate the acute effects of a warm-up on balance control and inter-limb balance asymmetries by analyzing the influence of the nature of the sport practiced by participants. Twelve sportspeople were recruited. They had to stand on a force plate for 30 s in a one-leg stance on their dominant (used to perform skilled movements) and non-dominant leg (used to support the body) before and 2, 5, 10, 15 and 20 min after a 10 min warm-up exercise performed at moderate intensity on a cycle ergometer. The center of foot pressure displacements was recorded. Statistical analysis was performed by considering one group of all participants and with two subgroups according to the symmetrical or asymmetrical nature of the sport they practiced. The warm-up exercise improved acute balance control only on the dominant leg after a 20 min rest without significantly reducing inter-limb balance asymmetries. This effect was more characteristic of participants with experience in asymmetric sports. These results confirm previous findings of the greater sensitivity of the dominant leg to the physiological state and reveal that between-leg differences in balance control appear mainly in subjects with experience in asymmetric sports in a specific physiological condition (post-warm-up state).


Assuntos
Exercício de Aquecimento , Pé/fisiologia , Humanos , Perna (Membro)/fisiologia , Movimento/fisiologia , Equilíbrio Postural/fisiologia
13.
J Sport Health Sci ; 11(1): 30-39, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-32439501

RESUMO

PURPOSE: This study aimed to compare biomechanical aspects of a novel "running" diagonal stride (DSRUN) with "conventional" diagonal stride (DSCONV) skiing techniques performed at high speed. METHODS: Ten elite Italian male junior cross-country skiers skied on a treadmill at 10 km/h and at a 10° incline utilizing both variants of the diagonal stride technique. The 3-dimensional kinematics of the body, poles, and roller skis; the force exerted through the poles and foot plantar surfaces; and the angular motion of the leg joints were determined. RESULTS: Compared to DSCONV, DSRUN demonstrated shorter cycle times (1.05 ± 0.05 s vs. 0.75 ± 0.03 s (mean ± SD), p < 0.001) due to a shorter rolling phase (0.40 ± 0.04 s vs. 0.09 ± 0.04 s, p < 0.001); greater force applied perpendicularly to the roller skis when they had stopped rolling forward (413 ± 190 N vs. 890 ± 170 N, p < 0.001), with peak force being attained earlier; prolonged knee extension, with a greater range of motion during the roller ski-stop phase (28° ± 4° vs. 16° ± 3°, p = 0.00014); and more pronounced hip and knee flexion during most of the forward leg swing. The mechanical work performed against friction during rolling was significantly less with DSRUN than with DSCONV (0.04 ± 0.01 J/m/kg vs. 0.10 ± 0.02 J/m/kg, p < 0.001). CONCLUSION: Our findings demonstrate that DSRUN is characterize by more rapid propulsion, earlier leg extension, and a greater range of motion of knee joint extension than DSCONV. Further investigations, preferably on snow, should reveal whether DSRUN results in higher acceleration and/or higher peak speed.


Assuntos
Corrida , Esqui , Fenômenos Biomecânicos , Teste de Esforço , Humanos , Articulação do Joelho , Masculino
14.
Curr Biol ; 31(19): R1138-R1140, 2021 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-34637718

RESUMO

Can the neural activity expressing the same mental processes in two different individuals be somehow aligned? Recent evidence suggests that in some cases it can, in mice, at least when they think about space, but possibly even when conjuring up something more abstract.


Assuntos
Processos Mentais , Animais , Camundongos
15.
eNeuro ; 8(5)2021.
Artigo em Inglês | MEDLINE | ID: mdl-34330819

RESUMO

Shifts in spatial patterns produced during the execution of a navigational task can be used to track the effects of the accumulation of knowledge and the acquisition of structured information about the environment. Here, we provide a quantitative analysis of mice behavior while performing a novel goal localization task in a large, modular arena, the HexMaze. To demonstrate the effects of different forms of previous knowledge we first obtain a precise statistical characterization of animals' paths with sub-trial resolution and over different phases of learning. The emergence of a flexible representation of the task is accompanied by a progressive improvement of performance, mediated by multiple, multiplexed time scales. We then use a generative mathematical model of the animal behavior to isolate the specific contributions to the final navigational strategy. We find that animal behavior can be accurately reproduced by the combined effect of a goal-oriented component, becoming stronger with the progression of learning, and of a random walk component, producing choices unrelated to the task and only partially weakened in time.


Assuntos
Aprendizagem , Navegação Espacial , Animais , Comportamento Animal , Camundongos
16.
J Therm Biol ; 98: 102925, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-34016347

RESUMO

PURPOSE: To investigate the effects of a very short-term acclimation protocol (VSTAP) on performance, physiological and perceptual responses to exercise in the heat. METHODS: 12 trained male cyclists (age 31.2 ± 7; weight 71.3 ± 7 kg, VO2max: 58.4 ± 3.7 mL/kg/min) randomly performed two Time to Exhaustion Tests (TTE) at 75% of normothermic peak power output (PPO), one in normothermia (N,18°C-50% RH) and one in the heat (H,35°C-50% RH), before and after a VSTAP intervention, consisting of 3 days-90 min exercise (10min at 30% of PPO+80 min at 50% of PPO) in H (≈4.5h of heat exposure). Performance time of TTEs and physiological and perceptual variables of both TTEs and training sessions (T1, T2 and T3) were evaluated. RESULTS: Magnitude Based Inferences (MBI) revealed 92/6/1% and 62/27/11% chances of positive/trivial/negative effects of VSTAP of improving performance in H (+17%) and in N (+9%), respectively. Heart Rate (HR) decreased from T1 to T3 (p < 0.001) and T2 to T3 (p < 0.001), whereas Tympanic Temperature (TyT) decreased from T1 to T2 (p = 0.047) and from T1 to T3 (p = 0.007). Furthermore, despite the increased tolerance to target Power Output (PO) throughout training sessions, RPE decreased from T1 to T3 (p = 0.032). CONCLUSIONS: The VSTAP determined meaningful physiological (i.e. decreased HR and TyT) and perceptual (i.e. decreased RPE) adaptations to submaximal exercise. Furthermore, showing good chances to improve performance in the heat, it represents a valid acclimation strategy to be implemented when no longer acclimation period is possible. Finally, no cross-over effect of the VSTAP on performance in temperate conditions was detected.


Assuntos
Aclimatação/fisiologia , Ciclismo/fisiologia , Exercício Físico/fisiologia , Temperatura Alta , Adulto , Humanos , Masculino , Resistência Física , Adulto Jovem
17.
Eur J Appl Physiol ; 121(7): 2061-2076, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33811558

RESUMO

PURPOSE: This study investigated the effect of performing hypoxic exercise at the same heart rate (HR) or work rate (WR) as normoxic exercise on post-exercise autonomic and cardiovascular responses. METHODS: Thirteen men performed three interval-type exercise sessions (5 × 5-min; 1-min recovery): normoxic exercise at 80% of the WR at the first ventilatory threshold (N), hypoxic exercise (FiO2 = 14.2%) at the same WR as N (H-WR) and hypoxic exercise at the same HR as N (H-HR). Autonomic and cardiovascular assessments were conducted before and after exercise, both at rest and during active squat-stand manoeuvres (SS). RESULTS: Compared to N, H-WR elicited a higher HR response (≈ 83% vs ≈ 75%HRmax, p < 0.001) and H-HR a reduced exercise WR (- 21.1 ± 9.3%, p < 0.001). Cardiac parasympathetic indices were reduced 15 min after exercise and recovered within 60 min in N and H-HR, but not after H-WR (p < 0.05). H-WR altered cardiac baroreflex sensitivity (cBRS) both at rest and during SS (specifically in the control of blood pressure fall during standing phases) in the first 60 min after the exercise bout (p < 0.05). Post-exercise hypotension (PEH) did not occur in H-HR (p > 0.05) but lasted longer in H-WR than in N (p < 0.05). CONCLUSIONS: Moderate HR-matched hypoxic exercise mimicked post-exercise autonomic responses of normoxic exercise without resulting in significant PEH. This may relate to the reduced WR and the limited associated mechanical/metabolic strain. Conversely, WR-matched hypoxic exercise impacted upon post-exercise autonomic and cardiovascular responses, delaying cardiac autonomic recovery, temporarily decreasing cBRS and evoking prolonged PEH.


Assuntos
Sistema Nervoso Autônomo/fisiologia , Fenômenos Fisiológicos Cardiovasculares , Exercício Físico/fisiologia , Hipóxia/fisiopatologia , Adulto , Biomarcadores/sangue , Frequência Cardíaca/fisiologia , Monitorização Hemodinâmica , Humanos , Lactatos/sangue , Masculino
19.
Artigo em Inglês | MEDLINE | ID: mdl-32878130

RESUMO

We examined whether trained women exhibit similar cardiovascular and cardiac baroreflex alterations after a half-marathon compared to men. Thirteen women (39.1 ± 9.3 years; 165 ± 6 cm; 58.2 ± 7.5 kg; maximal aerobic speed (MAS): 13.7 ± 2.2 km·h-1) and 12 men (45.7 ± 10.5 years; 178 ± 7 cm; 75.0 ± 8.3 kg; MAS: 15.8 ± 2.2 km·h-1) ran an official half-marathon. Before and 60-min after, cardiovascular variables, parasympathetic (heart rate variability analysis) modulation and cardiac baroreflex function (transfer function and sequence analyses) were assessed during supine rest and a squat-stand test. Running performance was slower in women than in men (120 ± 19 vs. 104 ± 14 min for women and men, respectively). However, when expressed as a percentage of MAS, it was similar (78.1 ± 4.6% and 78.2 ± 5.4% of MAS for women and men, respectively). Before the run, women exhibited lower mean blood pressure (BP), cardiac output (CO) and stroke volume (SV) compared to men, together with higher parasympathetic indexes. After the race, parasympathetic indexes decreased in both sexes, but remained higher in women. Reduced SV, systolic BP and cardiac baroreflex were observed in men but not in women. Contrary to men, a competitive half-marathon did not trigger post-exercise hypotension and a reduced cardiac baroreflex in women.


Assuntos
Barorreflexo , Hipotensão Pós-Exercício , Corrida , Adulto , Pressão Sanguínea , Feminino , Frequência Cardíaca , Humanos , Masculino , Pessoa de Meia-Idade , Corrida/fisiologia
20.
High Alt Med Biol ; 21(3): 249-257, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32412801

RESUMO

Fornasiero, Alessandro, Aldo Savoldelli, Federico Stella, Alexa Callovini, Lorenzo Bortolan, Andrea Zignoli, David A. Low, Laurent Mourot, Federico Schena, and Barbara Pellegrini. Shortening work-rest durations reduces physiological and perceptual load during uphill walking in simulated cold high-altitude conditions. High Alt Med Biol. 21:249-257, 2020. Background: We investigated the effects of two different work-rest durations on the physiological and perceptual responses to a simulated mountain hike in a cold hypoxic environment. Materials and Methods: Twelve healthy nonacclimatized active men (age 31.3 ± 5.3 years, body mass index 22.4 ± 1.5 kg/m2) completed a 80-minute work-matched intermittent exercise on a motorized treadmill (25% incline, fixed self-selected speed), in a simulated mountain environment (-25°C, FiO2 = 11%, ≈5000 m a.s.l.), wearing extreme cold weather gear, once with short (20 × 3 minutes walking with 1 minute rest; SHORT) and once with long (10 × 6 minutes walking with 2 minutes rest; LONG) work-rest durations. Heart rate (HR), pulse oxygen saturation (SpO2), rate of perceived exertion (RPE), and thermal sensation (TS) were assessed throughout the exercise protocols. Cardiac autonomic modulation was assessed before (PRE) and after exercise (POST) in supine position, as well as during standing resting periods by means of HR recovery (HRR) assessment. Results: SpO2 and TS were similar (p > 0.05) in SHORT and LONG protocols. HR and RPE were increased, and HRR reduced during LONG compared to SHORT (p < 0.05). Parasympathetic activity indices were reduced at POST after both protocols (p < 0.05), but to a lesser extent after SHORT (p < 0.05). Conclusions: Reduced work-rest durations are associated with improved perceptual responses and less perturbation of cardiac autonomic balance, compared to longer work-rest durations. Shorter exercise periods from more frequent breaks during hikes at high altitude may represent a valid strategy to limit the impact of exercise under extreme environmental conditions.


Assuntos
Altitude , Caminhada , Adulto , Exercício Físico , Frequência Cardíaca , Humanos , Masculino , Descanso
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