Christof Andreas Leicht

Study Design Randomised, single blind, sham-controlled parallel trial Objectives To determine the feasibility of delivering and acceptability of an upper-limb ischaemic preconditioning (IPC) protocol and to explore its acute effect on elbow extension strength and endurance in chronic spinal cord injury (SCI). Setting Outpatient spinal injuries centre, UK Methods Thirty-eight community-dwelling adults at least one-year post-SCI (m. triceps brachii Medical Research Council grade at least 4/5) were randomised (19 IPC, 19 sham) from 770 screened, of which 37 received the allocated intervention. Feasibility was assessed via adherence, adverse events and retention; acceptability via the Theoretical Framework of Acceptability questionnaire, McGill Pain Questionnaire and pain and discomfort ratings. Maximal isometric elbow extension force, intermittent isometric time to exhaustion and m. triceps brachii surface electromyography were assessed pre- and post- intervention. Results Adherence was 100% and retention rate was 97%. No adverse events were reported. IPC was rated more uncomfortable than sham (p < 0.001), but acceptability did not differ between the groups (p ≥ 0.257). Post-intervention strength and TTE did not differ between groups after adjusting for baseline (p = 0.292, p = 0.438). A significant interaction (p = 0.003) reflected lower triceps brachii sEMG at task failure following IPC. Conclusions Upper-limb IPC is feasible and acceptable in community dwelling adults with chronic SCI, but a single session protocol produced no significant changes in maximal elbow extension strength or endurance. The neuromuscular findings warrant investigation in an adequately powered efficacy trial.

Passive heat therapy can improve cardiometabolic health outcomes in some clinical populations, making it a potential therapeutic tool for individuals with spinal cord injury (SCI), who exhibit elevated cardiometabolic disease risk and face barriers to physical activity. Following a no‐intervention run‐in of 8 weeks (Control), 10 adults with chronic SCI (age: 48 ± 14 years; lesion level: C4–T12, body mass index: 29 ± 2) attended thrice weekly sessions over 8 weeks (Intervention), during which sublingual temperature was raised by 1°C using a water‐perfused suit and heated blankets. An oral glucose tolerance test, resting plasma interleukin 6, C‐reactive protein and tumour necrosis factor α concentration, as well as the skin hyperaemic response to local heating of 39°C and 45°C were assessed at baseline, after Control and Intervention. Adherence, safety and tolerability was monitored throughout the intervention. While one participant dropped‐out after 18 intervention sessions due to a medical issue unrelated to the intervention, adherence was 100% in the remaining nine participants and tolerated well. Glucose tolerance did not differ between Control and Intervention (glucose area under the curve Control: 7410 ± 6088 mg/dl*180min, Intervention: 8253 ± 2139 mg/dl*180min; P = 0.857). Similarly, neither inflammatory markers ( P > 0.055) nor hyperaemic responses to local skin heating ( P > 0.829) changed after intervention. In summary, passive heat therapy that raised sublingual temperature by 1°C was well tolerated, but did not change outcomes associated with cardiometabolic health and inflammation in persons with chronic SCI.

Individuals of South Asian (SA) descent display a higher risk for cardiovascular disease and type 2 diabetes mellitus than their White European (WE) counterparts. Heat therapy, such as hot water immersion (HWI), can improve microvascular function and glycaemic control, although effects across racial groups are unknown. This study compared how repeated HWI influenced microvascular function, glycaemic control and markers of inflammation in males of WE and SA descent. Ten WE and SA males completed ten 60 min HWI sessions over 14 days. Before and after HWI, forearm and great toe cutaneous vascular conductance (CVC) responses to postocclusive reactive hyperaemia and local heating (LH) were measured, resting blood samples were collected, and an oral glucose tolerance test (OGTT) was conducted. Baseline great toe CVC did not differ between racial groups ( P = 0.670), but forearm CVC was lower in SA ( P = 0.010). For postocclusive reactive hyperaemia, forearm and great toe peak CVC and area under the curve were unchanged by HWI ( P ≥ 0.300), whereas CVC during 42°C LH increased at both sites after HWI ( P ≤ 0.037), as did great toe CVC during 44°C LH ( P = 0.021). Glucose and insulin concentrations were elevated in SA during the OGTT ( P ≤ 0.035); glucose concentration and peak insulin reduced after HWI in SA ( P ≤ 0.024), but not in WE. The interleukin‐6:interleukin‐10 ratio was unchanged by HWI ( P = 0.159), but elevated in SA ( P = 0.006). Repeated HWI increased microvascular responses to LH to a similar extent between racial groups and reduced early‐phase OGTT glucose concentrations in SA, although insulin sensitivity was unchanged. These findings support HWI as a health‐promoting intervention.

The aim of this study was to determine whether inflammatory and vascular responses to passive heating differ between the early follicular phase (EFP) and the mid‐luteal phase (MLP) of the menstrual cycle. Ten healthy, naturally menstruating females (26 ± 3 years of age; body mass index 21.4 ± 1.9 kg/m²) were assessed during EFP and MLP. Participants underwent 60 min whole‐body passive heat exposure (71°C ± 2°C, dry heat) in both phases. Outcomes included body temperature, interleukin‐6, interleukin‐1 receptor antagonist and plasma nitrite concentrations, cutaneous vascular conductance, blood pressure, arterial stiffness and perceptual responses. Rectal temperature and mean skin temperature increased during heat exposure but did not differ between EFP and MLP. Likewise, heat exposure increased interleukin‐6, interleukin‐1 receptor antagonist and plasma nitrite concentrations, with no differences between menstrual cycle phases. However, brachial (EFP, 75 ± 4 mmHg vs MLP, 72 ± 5 mmHg; p = 0.040) and central (EFP, 75 ± 4 mmHg vs MLP, 72 ± 5 mmHg; p = 0.042) mean arterial pressures were higher in EFP than in MLP at 40 min of heat exposure. Additionally, arterial stiffness declined more in EFP (−13% ± 7%) than in MLP (−5% ± 6%; p = 0.019) from the end of heat exposure to 30 min into recovery. Perceptual responses, including thermal sensation and comfort, were similar between menstrual cycle phases, but skin wetness perception was heightened during EFP. In conclusion, the inflammatory and plasma nitrite responses to passive heating did not differ between EFP and MLP. However, some vascular function and perception parameters were affected by the menstrual cycle phase.

A disability determines exercise modality, movement patterns, and the amount of active skeletal muscle mass; these all affect athletic performance and generally reduce the physiological responses to exercise. As a result, people with disabilities are more prone to physical inactivity and are often at increased risk for cardiovascular and inflammation-related diseases. However, due to the wide range of physical disabilities, the physiological response to exercise is not uniform across individuals with a disability. Several factors, such as autonomic dysfunction, the extent to which active skeletal muscle mass is reduced, and the ability to increase body temperature through activity, influence the inflammatory response to exercise. Disabilities such as spinal cord injury, which are characterised by autonomic dysfunction, as well as a limited skeletal muscle mass and physical capacity to raise body temperature through exercise, may hence result in an impaired inflammatory response. Additionally, ageing may further deteriorate the inflammatory state. Whilst chronic studies in populations with disabilities are scarce, the available evidence indicates that the inflammatory resting profile is a modifiable risk factor, and exercise as well as interventions that mimic part of the exercise stimulus have been shown to result in favourable inflammatory responses across the disability spectrum.

Background/Objectives: Rates of depression, anxiety, sleep disturbances, and chronic pain are higher in people with spinal cord injury (SCI) compared with able-bodied individuals. Passive heat therapy (PHT), which raises core body temperature, may be an accessible therapeutic intervention. The effects of PHT on mental health, sleep, and pain in persons with SCI are unknown. Methods: We performed a time-controlled pre–post intervention pilot study in which ten veterans with chronic SCI underwent an 8-week supervised PHT intervention to raise oral temperature by 1 °C each session. Outcome measures were the 5-item Mental Health Inventory, Epworth Sleepiness Scale, and International Spinal Cord Injury Pain Extended Data Sets version 1.0. Results: There were no adverse events related to the intervention and nine out of ten participants completed all their intervention sessions. There was a reduction in pain intensity (p = 0.039) upon completing the intervention (from a median (IQR) of 2.0 (0.0, 3.5) to 1.0 (0.0, 4.5) on a 0–10 scale). However, there were no improvements in self-reported mental health or sleep outcomes (p > 0.339). Conclusions: This pilot study suggests that supervised repeated passive heat therapy may confer benefits for chronic pain in veterans with chronic SCI. Follow-up studies with larger sample sizes and more extensive sets of chronic pain outcomes are needed to confirm these findings.

Background/Objectives: Rates of depression, anxiety, sleep disturbances, and chronic pain are higher in people with spinal cord injury (SCI) compared with able-bodied (AB) individuals. Passive heat therapy (PHT) that raises core body temperature may be an accessible alternative to exercise in SCI. The effects of PHT on mental health, sleep, and pain in persons with SCI are unknown. Methods: We performed a pre-post intervention pilot study in which ten veterans with chronic SCI underwent an 8-week supervised passive heat therapy intervention to raise oral temperature by 1℃. Outcome measures were the 5-item Mental Health Inventory, Epworth Sleepiness Scale, and International Spinal Cord Injury Pain Extended Data Sets version 1.0. Results: There were no adverse events related to the intervention and nine out of ten participants completed all their intervention sessions. There was a reduction in pain intensity (p=0.039) upon completing the intervention. However, there were no improvements in self-reported mental health nor sleep outcomes (p=0.339). Conclusions: This pilot study suggests that supervised repeated passive heat therapy may confer benefits for chronic pain in veterans with chronic SCI. Follow-up study with a larger sample size and a more extensive set of chronic pain outcomes is needed to confirm these findings.

Purpose: Heat therapy is recognised to promote cardiovascular health, and whilst most recent heat therapy investigations have focussed on continuous heat exposure, traditional sauna use often includes recovery periods. This study compared the acute effects of continuous versus intermittent whole-body heating on cardiovascular function markers in males and females. Methods: Twenty healthy participants (25 ± 3 years; 10 males, 10 females) were exposed to 2 passive heating regimens: continuous heating (CH) for 60 min and intermittent heating (IH) comprised of 3 × 20-min blocks interspersed by 15-min cooling breaks. Skin perfusion, blood pressure (BP), plasma nitrite, interleukins, body temperature, and thermal perceptual responses were assessed. Results: Greater increases in rectal temperature (T_rec) (CH: 1.2 ± 0.1 °C; IH: 0.5 ± 0.1 °C), skin perfusion, systolic blood pressure (SBP), heart rate (HR), interleukin-6 (IL-6) and plasma nitrite were found in CH compared to IH (p ≤ 0.01), but the thermal perceptual response was more unfavourable during CH (p < 0.01). Females had higher skin perfusion and plasma nitrite concentrations (p ≤ 0.04), but lower brachial and central BP than males in both conditions (p ≤ 0.01). Furthermore, females reached a higher T_rec and more unfavourable thermal perception in CH (p ≤ 0.02). Conclusion: More pronounced cardiovascular responses were associated with higher T_rec and discomfort. Females exhibited higher skin perfusion and plasma nitrite concentrations than males and reported less favourable thermal perception in CH, but not in IH.

Passively elevating body temperature can trigger a potentially beneficial acute inflammatory response. However, heat therapy often causes discomfort and negative thermal perceptions, particularly in females who generally have lower heat tolerance than males. This study aimed to evaluate the impact of facial cooling on thermal comfort and interleukin-6 concentration in response to 60 minutes of dry heat exposure, and to investigate sex differences in physiological responses and perceptions. 22 healthy young adults (10 females, 12 males; age: 24.4 ± 3.3 years) completed three trials in randomized order using a dry sauna device: 1) Hyperthermia (71.1 ± 1.9°C; HEAT), 2) Hyperthermia with facial cooling via fans (71.1 ± 3.0°C; FAN), and 3) Normothermia (27.0 ± 0.9°C; CON). Blood samples to determine interleukin-6 (IL-6) plasma concentration were collected before and after exposure; basic affect and thermal comfort, rectal and skin temperature were assessed throughout the intervention. Rectal temperature following HEAT (38.0 ± 0.3°C) and FAN (37.8 ± 0.3°C) did not differ between males and females (p = 0.57). Females had higher forehead skin temperatures than males (p ≤ 0.019). Thermal comfort remained more positive in FAN compared to HEAT (p ≤ 0.002). Females felt more thermal discomfort than males in HEAT (p ≤ 0.03), but not in FAN (p = 0.28). The increase in IL-6 plasma concentration was similar between HEAT and FAN (p = 1.00), and higher than CON (p ≤ 0.02); there was no difference between males and females (p = 0.69). This study showed that facial cooling alleviated the thermal discomfort during heat exposure, particularly benefitted females, and did not impede the acute IL-6 response.