Thermoregulation is not impaired in breast cancer survivors during moderate-intensity exercise performed in warm and hot environments.

This study aimed to assess how female breast cancer survivors (BCS) respond physiologically, hematologically, and perceptually to exercise under heat stress compared to females with no history of breast cancer (CON). Twenty-one females (9 BCS and 12 CON [age; 54 ± 7 years, stature; 167 ± 6 cm, body mass; 68.1 ± 7.62 kg, and body fat; 30.9 ± 3.8%]) completed a warm (25℃, 50% relative humidity, RH) and hot (35℃, 50%RH) trial in a repeated-measures crossover design. Trials consisted of 30 min of rest, 30 min of walking at 4 metabolic equivalents, and a 6-minute walk test (6MWT). Physiological measurements (core temperature (Tre ), skin temperature (Tskin ), heart rate (HR), and sweat analysis) and perceptual rating scales (ratings of perceived exertion, thermal sensation [whole body and localized], and thermal comfort) were taken at 5- and 10-min intervals throughout, respectively. Venous blood samples were taken before and after to assess; IL-6, IL-10, CRP, IFN-γ, and TGF-ß1 . All physiological markers were higher during the 35 versus 25℃ trial; Tre (~0.25℃, p = 0.002), Tskin (~3.8℃, p < 0.001), HR (~12 beats·min-1 , p = 0.023), and whole-body sweat rate (~0.4 L·hr-1 , p < 0.001), with no difference observed between groups in either condition (p > 0.05). Both groups covered a greater 6MWT distance in 25 versus 35℃ (by ~200 m; p = 0.003). Nevertheless, the control group covered more distance than BCS, regardless of environmental temperature (by ~400 m, p = 0.03). Thermoregulation was not disadvantaged in BCS compared to controls during moderate-intensity exercise under heat stress. However, self-paced exercise performance was reduced for BCS regardless of environmental temperature.

Exercise heat acclimation and post-exercise hot water immersion improve resting and exercise responses to heat stress in the elderly.

OBJECTIVES: To investigate the efficacy of heat acclimation (HA) in the young (YEX) and elderly (EEX) following exercise-HA, and the elderly utilising post-exercise hot water immersion HA (EHWI). DESIGN: Cross-sectional study. METHOD: Twenty-six participants (YEX: n = 11 aged 22 ±â€¯2 years, EEX:n = 8 aged 68 ±â€¯3 years, EHWI: n = 7 aged 73 ±â€¯3 years) completed two pre-/post-tests, separated by five intervention days. YEX and EEX exercised in hot conditions to raise rectal temperature (Trec) ≥38.5 °C within 60 min, with this increase maintained for a further 60 min. EHWI completed 30 min of cycling in temperate conditions, then 30 min of HWI (40 °C), followed by 30 min seated blanket wrap. Pre- and post-testing comprised 30 min rest, followed by 30 min of cycling exercise (3.5 W·kg-1 Hprod), and a six-minute walk test (6MWT), all in 35 °C, 50% RH. RESULTS: The HA protocols did not elicit different mean heart rate (HR), Trec, and duration Trec ≥ 38.5 °C (p > 0.05) between YEX, EEX, and EHWI groups. Resting Trec, peak skin temperature, systolic and mean arterial pressure, perceived exertion and thermal sensation decreased, and 6MWT distance increased pre- to post-HA (p < 0.05), with no difference between groups. YEX also demonstrated a reduction in resting HR (p < 0.05). No change was observed in peak Trec or HR, vascular conductance, sweat rate, or thermal comfort in any group (p > 0.05). CONCLUSIONS: Irrespective of age or intervention, HA induced thermoregulatory, perceptual and exercise performance improvements. Both exercise-HA (EEX), and post-exercise HWI (EHWI) are considered viable interventions to prepare the elderly for heat stress.

Short-term heat acclimation prior to a multi-day desert ultra-marathon improves physiological and psychological responses without compromising immune status.

Multistage, ultra-endurance events in hot, humid conditions necessitate thermal adaptation, often achieved through short term heat acclimation (STHA), to improve performance by reducing thermoregulatory strain and perceptions of heat stress. This study investigated the physiological, perceptual and immunological responses to STHA prior to the Marathon des Sables. Eight athletes (age 42 ± 4 years and body mass 81.9 ± 15.0 kg) completed 4 days of controlled hyperthermia STHA (60 min·day‒1, 45°C and 30% relative humidity). Pre, during and post sessions, physiological and perceptual measures were recorded. Immunological measures were recorded pre-post sessions 1 and 4. STHA improved thermal comfort (P = 0.02), sensation (P = 0.03) and perceived exertion (P = 0.04). A dissociated relationship between perceptual fatigue and Tre was evident after STHA, with reductions in perceived Physical (P = 0.04) and General (P = 0.04) fatigue. Exercising Tre and HR did not change (P > 0.05) however, sweat rate increased 14% (P = 0.02). No changes were found in white blood cell counts or content (P > 0.05). Four days of STHA facilitates effective perceptual adaptations, without compromising immune status prior to an ultra-endurance race in heat stress. A greater physiological strain is required to confer optimal physiological adaptations.

Similar Inflammatory Responses following Sprint Interval Training Performed in Hypoxia and Normoxia.

Sprint interval training (SIT) is an efficient intervention capable of improving aerobic capacity and exercise performance. This experiment aimed to determine differences in training adaptations and the inflammatory responses following 2 weeks of SIT (30 s maximal work, 4 min recovery; 4-7 repetitions) performed in normoxia or hypoxia. Forty-two untrained participants [(mean ± SD), age 21 ±1 years, body mass 72.1 ±11.4 kg, and height 173 ±10 cm] were equally and randomly assigned to one of three groups; control (CONT; no training, n = 14), normoxic (NORM; SIT in FiO2: 0.21, n = 14), and normobaric hypoxic (HYP; SIT in FiO2: 0.15, n = 14). Participants completed a [Formula: see text] test, a time to exhaustion (TTE) trial (power = 80% [Formula: see text]) and had hematological [hemoglobin (Hb), haematocrit (Hct)] and inflammatory markers [interleukin-6 (IL-6), tumor necrosis factor-α (TNFα)] measured in a resting state, pre and post SIT. [Formula: see text] (mL.kg(-1).min(-1)) improved in HYP (+11.9%) and NORM (+9.8%), but not CON (+0.9%). Similarly TTE improved in HYP (+32.2%) and NORM (+33.0%), but not CON (+3.4%) whilst the power at the anaerobic threshold (AT; W.kg(-1)) also improved in HYP (+13.3%) and NORM (+8.0%), but not CON (-0.3%). AT (mL.kg(-1).min(-1)) improved in HYP (+9.5%), but not NORM (+5%) or CON (-0.3%). No between group change occurred in 30 s sprint performance or Hb and Hct. IL-6 increased in HYP (+17.4%) and NORM (+20.1%), but not CON (+1.2%), respectively. TNF-α increased in HYP (+10.8%) NORM (+12.9%) and CON (+3.4%). SIT in HYP and NORM increased [Formula: see text], power at AT and TTE performance in untrained individuals, improvements in AT occurred only when SIT was performed in HYP. Increases in IL-6 and TNFα reflect a training induced inflammatory response to SIT; hypoxic conditions do not exacerbate this.