Mid Sweden University

We investigated integrative physiological responses to eupnoeic exercise (EX), rebreathing exercise (RB), dynamic apnoea (DA) and dynamic apnoea with cold-water face immersion (DAFI) in 20 healthy participants. Trials involved non-steady-state cycle exercise at 60 W for an average duration of 66 s. With increases in heart rate and stroke volume, EX and RB increased cardiac output compared with baseline (mean [SD] EX +47 [13]%, RB +43 [15]%). During DA and DAFI, the increase in cardiac output was attenuated (DA +26 [23]%, DAFI +14 [21]%). EX and RB elicited reductions in total peripheral resistance (EX −37 [7]%, RB −23 [15]%). This reduction was absent during apnoeas (DA +3 [31]%, DAFI +15 [40]%). Pulmonary oxygen uptake was the lowest during DAFI. At the end of hypoxic trials, end-tidal partial pressures of O<inf>2</inf> were RB 50.3 [11.9], DA 57.9 [14.0] and DAFI 61.4 [13.6] mmHg, indicating a preservation of the central oxygen store during DA and DAFI. At the same time, peripheral tissue oxygen saturation, measured in the working rectus femoris muscle, declined the most during DA and DAFI (RB −1.4 [3.5]%, DA −4.7 [3.3]%, DAFI −5.6 [4.4]%). Splenic volume increased during EX (+8.4 [5.8]%) but decreased during RB (−10.5 [10.2]%), DA (−6.4 [10.8]) and DAFI (−13.3 [11.1]%) when compared with EX, suggesting erythrocyte mobilization in the threat of hypoxia. The non-steady-state apnoea interventions of the present study evoke a progressive shift from exercise-induced cardiovascular responses towards a diving response, including cardiac, vascular and splenic responses. These responses are amplified to some extent by cold-water face immersion. Apnoea-induced responses lead to central oxygen preservation and a decrease in peripheral oxygen stores. 

This study explores the implementation of a lifestyle programme within municipal mental health services from the perspectives of staff working with housing support, focusing on the challenges and facilitators that shaped its delivery over time. Drawing on longitudinal data collected across three time points, the findings highlight the complexity of implementing lifestyle programmes in fragmented service environments. While early stages were marked by staff engagement and contextual adaptation, sustainability was hindered by staff turnover, limited organisational anchoring, and unclear responsibilities. The Consolidated Framework for Implementation Research was used to analyse how organisational context, leadership, and timing influenced outcomes. The study underscores the importance of shared responsibility, embedded support structures, and flexible implementation strategies. It also points to the potential of cross-sector collaboration, particularly with third sector organisations, as a means of sustaining preventive efforts when internal resources are constrained. Overall, the findings contribute to a deeper understanding of how complex interventions can be adapted and maintained in real-world mental health settings.

To make higher education accessible for all students and to enable inclusive learning, teachers face high demands in pedagogic knowledge and skills. This assumes knowledge of students with neuropsychiatric disorders (NPDs) as well as specific skills on how to implement suitable pedagogical adaptations. Applicable pedagogic adaptations to this growing student group have also been shown to be beneficial for larger general student populations. However, teachers often indicate difficulties finding and executing adequate pedagogical approaches. There are also knowledge gaps regarding how teachers adapt and accommodate their education and what kind of support they need. The study was designed in two phases: in the first phase the aims were to explore (a) teachers’ knowledge of students with NPDs, and (b) teachers' need of support to implement suitable pedagogical adaptations. The aim of the second phase is to develop a digital technological support system for teachers to be used forhands-on inclusive learning skills. This study was conducted with an action research approach where two of the authors also have been teachers in some of the investigated courses. A questionnaire was constructed and distributed to teachers within various subjects at a Swedish university, targeting their experiences and needs ineducational practice with students with NPDs. The questionnaire involved a combination of background items and open-ended items. Experiences and needs were analysed with reflexive thematic analysis. The questionnaire was the first step in a process of developing a digital technological support system for teachers, based on specific gaps of knowledge and their need for support. 85 out of 260 teachers responded to the survey; 68 % of respondents were women. 42 % were seniorlecturing staff, 49 % junior staff and 9% PhD students. 57% reported that they had not sufficient knowledge about students with NPDs. Teachers described various pedagogical knowledge for accommodating students with NPDs, including universal, individual and relational strategies. Examples were to increase clarity and predictability in all educational efforts, being prepared to flexibly adapt to student needs including increasing teacher availability and strengthening the relation by creating trust and safe communication. Teachers also described their own needs of in-depth knowledge, hands-on guidance, expert advice, and common solutions/discussions with colleagues. They also saw the need for improved organisational structures and support. The findings indicate that despite university teachers being aware of different pedagogical strategies, they still need to develop their knowledge. The knowledge gained from this study will be used as the foundation for development of a digital technological support system for teachers, which can be motivated from three perspectives: to strengthen teachers’ knowledge and skills; to strengthen students’ opportunities to participate in higher education; and to enable the organisation to evaluate and reassure their commitments regulated by laws or regulations. Future research in line with this study may be to implement an artificial intelligence (AI) tool in the digital technological support system.

Introduction The pulmonary oxygen uptake is reduced during apnea, compared to eupneic baseline, preserving the pulmonary oxygen store. This study elucidates the time course for this reduction, comparing it to the time course for apnea-induced cardiovascular responses.Methods and results Experiments involved two groups, performing apneas during rest, both without and with cold-water face immersion (A and AFI). The first group (n = 18) performed A and AFI of gradually increasing durations (from 15 to 120 s, order unknown to participant), allowing analysis of the time course for apneic pulmonary gas exchange. The second group (n = 18) performed A and AFI of identical durations (mean: 137 s), allowing analysis of cardiovascular and respiratory responses. The time course for pulmonary oxygen uptake was similar to the time courses for heart rate and cardiac output, i.e., following a brief increase from eupneic baseline during the initial 15 s of A and AFI, the oxygen uptake was gradually reduced during apnea, reaching a sub-eupneic level from 30 s of apnea and onwards. Changes were augmented during AFI compared to A. Observations confirmed that cardiovascular responses to apnea, including a reduced cardiac output, reduced peripheral blood flow, and most likely a peripheralization of blood volume, preserved the pulmonary oxygen store, while the peripheral venous oxygen stores were depleted to a greater extent.Conclusions We conclude that the central, pulmonary oxygen store is preserved with augmented cardiovascular responses to apnea, at the expense of peripheral venous oxygen stores, with a time course similar to that of the cardiovascular responses.

The spleen contracts during apnea, releasing stored erythrocytes, thereby increasing systemic hemoglobin concentration (Hb). We compared apnea and rebreathing periods, of equal sub-maximal duration (mean 137 s; SD 30), in eighteen subjects to evaluate whether respiratory arrest or hypoxic and hypercapnic chemoreceptor stimulation is the primary elicitor of splenic contraction and cardiovascular responses during apnea. Spleen volume, Hb, cardiovascular variables, arterial (SaO2), cerebral (ScO2), and deltoid muscle oxygen saturations (SmO2) were recorded during the trials and end-tidal partial pressure of oxygen (PETO2) and carbon dioxide (PETCO2) were measured before and after maneuvers. The spleen volume was smaller after apnea, 213 (89) mL, than after rebreathing, 239 (95) mL, corresponding to relative reductions from control by 20.8 (17.8) % and 11.6 (8.0) %, respectively. The Hb increased 2.4 (2.0) % during apnea, while there was no significant change with rebreathing. The cardiovascular responses, including bradycardia, decrease in cardiac output, and increase in total peripheral resistance, were augmented during apnea compared to during rebreathing. The PETO2 was higher, and the PETCO2 was lower, after apnea compared to after rebreathing. The ScO2 was maintained during maneuvers. The SaO2 decreased 3.8 (3.1) % during apnea, and even more, 5.4 (4.4) %, during rebreathing, while the SmO2 decreased less during rebreathing, 2.2 (2.8) %, than during apnea, 8.3 (6.2) %. We conclude that respiratory arrest per se is an important stimulus for splenic contraction and Hb increase during apnea, as well as an important initiating factor for the apnea-associated cardiovascular responses and their oxygen-conserving effects. 

Breath-hold diving (freediving) is an underwater sport that is associated with elevated hydrostatic pressure, which has a compressive effect on the lungs that can lead to the development of pulmonary edema. Pulmonary edema reduces oxygen uptake and thereby the recovery from the hypoxia developed during freediving, and increases the risk of hypoxic syncope. We aimed to examine the efficacy of SpO2, via pulse-oximetry, as a tool to detect pulmonary edema by comparing it to lung ultrasound B-line measurements after deep diving. SpO2 and B-lines were collected in 40 freedivers participating in an international deep freediving competition. SpO2 was measured within 17 ± 6 min and lung B-lines using ultrasound within 44 ± 15 min after surfacing. A specific symptoms questionnaire was used during SpO2 measurements. We found a negative correlation between B-line score and minimum SpO2 (rs = −0.491; p = 0.002) and mean SpO2 (rs = −0.335; p = 0.046). B-line scores were positively correlated with depth (rs = 0.408; p = 0.013), confirming that extra-vascular lung water is increased with deeper dives. Compared to dives that were asymptomatic, symptomatic dives had a 27% greater B-line score, and both a lower mean and minimum SpO2 (all p &lt; 0.05). Indeed, a minimum SpO2 ≤ 95% after a deep dive has a positive predictive value of 29% and a negative predictive value of 100% regarding symptoms. We concluded that elevated B-line scores are associated with reduced SpO2 after dives, suggesting that SpO2 via pulse oximetry could be a useful screening tool to detect increased extra-vascular lung water. The practical application is not to diagnose pulmonary edema based on SpO2 – as pulse oximetry is inexact – rather, to utilize it as a tool to determine which divers require further evaluation before returning to deep freediving.

Purpose: Splenic contraction increases circulating hemoglobin (Hb) with advantages during hypoxia. As both hypoxia and exercise have been shown to be important separate triggers of splenic contraction we aimed to investigate if the spleen response to simulated high altitude (HA) is enhanced by superimposing exercise. Method: Fourteen healthy volunteers (seven females) performed the following protocol in a normobaric environment sitting on an ergometer cycle: 20 min rest in normoxia; 20 min rest while breathing hypoxic gas simulating an altitude of 3500 m; 10 min exercise at an individually set intensity while breathing the hypoxic gas; 20 min rest in hypoxia; and finally 20 min rest in normoxia. Spleen measurements were collected by ultrasonic imaging and venous Hb measured at the end of each intervention. Result: Mean ± SD baseline spleen volume during normoxic rest was 280 ± 107 mL, the volume was reduced by 22% during rest in hypoxia to 217 ± 92 mL (p < 0.001) and by 33% during exercise in hypoxia (189 mL; p < 0.001). Hb was 140.7 ± 7.0 g/L during normoxic rest and 141.3 ± 7.4 g/L during hypoxic rest (NS), but increased by 5.3% during hypoxic exercise (148.6 ± 6.3 g/L; p < 0.001). Spleen volume and Hb were stepwise changed back to baseline at cessation of exercise and return to normoxia. Conclusion: Splenic contraction is induced by hypoxia and further enhanced by superimposing exercise, and reduced when exercise ceases, in a step-wise manner, showing that the tonic but partial contraction observed in long-term field expeditions to HA may occur also in the short term. This “graded response” may be beneficial during acclimatization to HA, to cope with moderate chronic hypoxia during rest while allowing additional enhancement of oxygen carrying capacity to overcome short bouts of extreme hypoxia caused by exercise. 

Robertson, C, Lodin-Sundström, A, O'Hara, J, King, R, Wainwright, B, and Barlow, M. Effects of pre-race apneas on 400-m freestyle swimming performance. J Strength Cond Res 34(3): 828–837, 2020—This study aimed to establish whether a series of 3 apneas before a 400-m freestyle time-trial affected swimming performance when compared with and combined with a warm-up. Nine (6 males and 3 females) regional to national standard swimmers completed four 400-m freestyle time-trials in 4 randomized conditions: without warm-up or apneas (CON), warm-up only (WU), apneas only (AP), and warm-up and apneas (WUAP). Time-trial performance was significantly improved after WUAP (275.79 ± 12.88 seconds) compared with CON (278.66 ± 13.31 seconds, p = 0.035) and AP (278.64 ± 4.10 seconds, p = 0.015). However, there were no significant differences between the WU (276.01 ± 13.52 seconds, p > 0.05) and other interventions. Spleen volume compared with baseline was significantly reduced after the apneas by a maximum of ∼45% in the WUAP and by ∼20% in WU. This study showed that the combination of a warm-up with apneas could significantly improve 400-m freestyle swim performance compared with a control and apnea intervention. Further investigation into whether long-term apnea training can enhance this response is justified.

Ingestion of dietary nitrate ([Formula: see text]) is associated with improved exercise tolerance and reduced oxygen (O2) cost of exercise, ascribed to enhanced mitochondrial efficiency, muscle contractile function, or other factors. Nitrate ingestion has also been found to attenuate the reduction in arterial oxygen saturation ([Formula: see text]) during apnea and to prolong apneic duration. The spleen serves as a dynamic blood pool expelling erythrocytes into the circulation during apnea, and [Formula: see text] and nitric oxide donors may induce vasoactive effects in the mesenteric and splanchnic circulation. Our aim was to investigate the effect of ingestion of concentrated organic [Formula: see text]-rich beetroot juice (BR) on spleen volume and spleen contraction during apnea, and the resulting hemoglobin (Hb) concentration. Eight volunteers performed two apneas of submaximal and maximal duration during prone rest ∼2.5 h after ingesting 70 mL of BR (∼5 mmol [Formula: see text]) or placebo (PL; ∼0.003 mmol [Formula: see text]), on separate days in weighted order. Heart rate and [Formula: see text] were monitored continuously and spleen diameters were measured every minute for triaxial volume calculation. Capillary Hb samples were collected at baseline and after the maximal apnea. Baseline spleen volume was reduced by 66 mL after BR ingestion (22.9%; P = 0.026) and Hb was elevated (+3.0%; P = 0.015). During apneas, spleen contraction and Hb increase were similar between BR and PL conditions (NS). The study shows that dietary [Formula: see text]reduces spleen volume at rest, resulting in increased Hb. This spleen-induced Hb elevation following [Formula: see text] ingestions represents a novel mechanism that could enhance performance in conditions involving exercise, apnea, and hypoxia.NEW & NOTEWORTHY This is the first study to examine changes of spleen volume and circulating Hb following dietary [Formula: see text] supplementation. After dietary [Formula: see text] ingestion, the spleen volume at rest was reduced and Hb was elevated. The spleen contains a dynamic red blood cell reservoir, which can be mobilized and facilitate oxygen transport during various types of physiological stress. This study has revealed an additional, previously unexplored mechanism possibly contributing to the ergogenic effects of dietary [Formula: see text].