Matthew R. Kuennen

Thermotolerance and heat acclimation may share a common mechanism in humans

Thermotolerance and heat acclimation are key adaptation processes that have been hitherto viewed as separate phenomena. Here, we provide evidence that these processes may share a common basis, as both may potentially be governed by the heat shock response. We evaluated the effects of a heat shock response-inhibitor (quercetin; 2,000 mg/day) on established markers of thermotolerance [gastrointestinal barrier permeability, plasma TNF-α, IL-6, and IL-10 concentrations, and leukocyte heat shock protein 70 (HSP70) content]. Heat acclimation reduced body temperatures, heart rate, and physiological strain during exercise/heat stress) in male subjects (n = 8) completing a 7-day heat acclimation protocol. These same subjects completed an identical protocol under placebo supplementation (placebo). Gastrointestinal barrier permeability and TNF-α were increased on the 1st day of exercise/heat stress in quercetin; no differences in these variables were reported in placebo. Exercise HSP70 responses were increased, and plasma cytokines (IL-6, IL-10) were decreased on the 7th day of heat acclimation in placebo; with concomitant reductions in exercise body temperatures, heart rate, and physiological strain. In contrast, gastrointestinal barrier permeability remained elevated, HSP70 was not increased, and IL-6, IL-10, and exercise body temperatures were not reduced on the 7th day of heat acclimation in quercetin. While exercise heart rate and physiological strain were reduced in quercetin, this occurred later in exercise than with placebo. Consistent with the concept that thermotolerance and heat acclimation are related through the heat shock response, repeated exercise/heat stress increases cytoprotective HSP70 and reduces circulating cytokines, contributing to reductions in cellular and systemic markers of heat strain. Exercising under a heat shock response-inhibitor prevents both cellular and systemic heat adaptations.

Exercise, but not acute sleep loss, increases salivary antimicrobial protein secretion.

Abstract Gillum, TL, Kuennen, MR, Castillo, MN, Williams, NL, and Jordan-Patterson, AT. Exercise, but not acute sleep loss, increases salivary antimicrobial protein secretion. J Strength Cond Res 29(5): 1359–1366, 2015—Sleep deficiencies may play a role in depressing immune parameters. Little is known about the impact of exercise after sleep deprivation on mucosal immunity. The purpose of this study was to quantify salivary antimicrobial proteins (AMPs) in response to sleep loss before and after exercise. Four men and 4 women (age: 22.8 ± 2; : 49.1 ± 7.1 ml·kg−1·min−1) completed 2 exercise trials consisting of 45 minutes of running at 75% after a normal night of sleep (CON) and after a night without sleep (WS). Exercise trials were separated by 10 ± 3 days. Saliva was collected before, immediately after, and 1 hour after exercise. LL-37, HNP1-3, Lactoferrin (Lac), and Lysozyme (Lys) were measured. Sleep loss did not affect the concentration or secretion rate of AMPs before or in response to exercise. However, exercise increased the concentration from pre- to post-exercise of LL-37 (pre: 15.5 ± 8.7; post: 22.3 ± 16.2 ng·ml−1), HNP1-3 (pre: 2.2 ± 2.3; post: 3.3 ± 2.5 &mgr;g·ml−1), Lac (pre: 5,234 ± 4,202; post: 12,283 ± 10,995 ng·ml−1), and Lys (pre: 5,831 ± 4,465; post: 12,542 ± 10,755 ng·ml−1), p ⩽ 0.05. The secretion rates were higher immediately after and 1 hour after exercise compared with before exercise for LL-37 (pre: 3.1 ± 2.1; post: 5.1 ± 3.7; +1: 6.9 ± 8.4 ng·min−1), HNP1-3 (pre: 0.38 ± 0.38; post: 0.80 ± 0.75; +1: 0.84 ± 0.67 &mgr;g·min−1), Lac (pre: 1,096 ± 829; post: 2,948 ± 2,923; +1: 2,464 ± 3,785 ng·min−1), and Lys (pre: 1,534 ± 1,790; post: 3,042 ± 2,773; +1: 1,916 ± 1,682 ng·min−1), p ⩽ 0.05. These data suggest that the major constituents of the mucosal immune system are unaffected by acute sleep loss and by exercise after acute sleep loss. Exercise increased the concentration and secretion rate of each AMP suggesting enhanced immunity and control of inflammation, despite limited sleep.

Salivary antimicrobial protein response to prolonged running.

Introduction Prolonged exercise may compromise immunity through a reduction of salivary antimicrobial proteins (AMPs). Salivary IgA (IgA) has been extensively studied, but little is known about the effect of acute, prolonged exercise on AMPs including lysozyme (Lys) and lactoferrin (Lac). Objective To determine the effect of a 50-km trail race on salivary cortisol (Cort), IgA, Lys, and Lac. Methods 14 subjects: (6 females, 8 males) completed a 50km ultramarathon. Saliva was collected pre, immediately after (post) and 1.5 hrs post race (+1.5). Results Lac concentration was higher at +1.5 hrs post race compared to post exercise (p < 0.05). Lys was unaffected by the race (p > 0.05). IgA concentration, secretion rate, and IgA/Osm were lower +1.5 hrs post compared to pre race (p < 0.05). Cort concentration was higher at post compared to +1.5 (p < 0.05), but was unaltered from pre race levels. Subjects finished in 7.81±1.2 hrs. Saliva flow rate did not differ between time points. Saliva Osm increased at post (p < 0.05) compared to pre race. Conclusions The intensity could have been too low to alter Lys and Lac secretion rates and thus, may not be as sensitive as IgA to changes in response to prolonged running. Results expand our understanding of the mucosal immune system and may have implications for predicting illness after prolonged running.

Fit persons are at decreased (not increased) risk of exertional heat illness.

In the review entitled ‘‘Influence of Aerobic Fitness on Thermoregulation during Exercise in the Heat,’’ Dr. MoraRodgriguez (3) stated that ‘‘When individuals can self-pace exerciseI fit individuals will be producing more heat and may fall into the higher risk category [than unfit] for heatrelated injuries.’’ We wish to challenge this statement. McLellan et al. (2) recently levied a similar challenge, arguing that because ‘‘aerobic fitness enhances thermotolerance,’’ trained persons can tolerate higher core temperatures than untrained. Our previous work (1) reaffirms the challenge by McLellan et al. (2) and lends credence to our own. In that study, eight subjects exercised (in athletic shorts/socks/shoes) to a core temperature of 39-C or higher for seven consecutive days. As shown in Panel A of the Figure, plasma endotoxin, interleukin-6 (IL-6), and IL-10 were reduced and heat shock protein 70 (HSP70) content (peripheral blood mononuclear cells) was increased after 7 d of repeated exercise-heat stress. We attributed the lack of increase in urinary lactulose excretion, plasma endotoxin, and tumor necrosis factor-> (TNF->) (indicators of gut permeability) preacclimation to the fact that this exercise was undertaken in fit subjects who had acquired some level of thermotolerance. These subjects also exhibited improvements (reduced core, skin, and mean body temperatures, heart rate, and physiologic strain) on a standardized heat tolerance test (1). We also assessed the impact that inhibiting the thermotolerance machinery (in the same eight subjects) had on endotoxin spillover, the ensuing inflammatory response, and achievement of the ‘‘heat-acclimated’’ state. We inhibited thermotolerance with an oral HSP70 blocker, which subjects began ingesting immediately before the first day of exercise-heat stress. As shown in Panel B of the Figure, gut permeability markers (urinary lactulose excretion, plasma endotoxin, TNF->) were elevated on the first day of exercise-heat stress. They remained elevated on the seventh day. Core, skin, and mean body temperatures did not improve (1). Improvements in heart rate and physiologic strain were attenuated (1). These data effectively underscore: 1) the existence of ‘‘enhanced thermotolerance in fit populations’’ (2); 2) the importance of thermotolerance in the heat acclimation response; and 3) the potential for thermotolerance to reduce risk for ‘‘heat-related injuries’’ (3) in fit populations. We conclude our letter with three observations:

Exercise does not increase salivary lymphocytes, monocytes, or granulocytes, but does increase salivary lysozyme

ABSTRACT An increase in salivary leukocytes may contribute to the exercise-induced increase in salivary antimicrobial proteins (AMPs). However, exercise-induced changes in salivary leukocytes have not been studied. The purpose of the study was to describe salivary leukocyte changes with exercise. Participants (n = 11, 20.3 ± 0.8 years, 57.2 ± 7.6 ml kg−1 min−1 peak oxygen uptake ((VO) ̇2peak), 11.1 ± 3.9% body fat) ran for 45 min at 75% of VO2peak. Stimulated saliva (12 mL) was collected pre- and immediately post exercise. Saliva was filtered through a 30 µm filter before analysis of leukocytes (CD45+), granulocytes (CD45+CD15+), monocytes (CD45+CD14+), T-cells (CD45+CD3+), and B-cells (CD45+CD20+) using flow cytometry. Saliva was analysed for Lysozyme (Lys) using ELISA. Exercise did not alter any leukocyte subset. The major constituent of leukocytes pre-exercise were granulocytes (57.9 ± 30.3% compared with monocytes: 5.1 ± 2.7%, T-cells: 17.1 ± 8.9%, B-cells: 12.1 ± 10.2%) (P < 0.05). In a subset of n = 6, Lys secretion rate increased after exercise (pre: 5,170 ± 5,215 ng/min; post: 7,639 ± 4,140 ng/min) (P < 0.05). Exercise does not result in increased granulocytes, but does increase Lys. Further, these data suggest that an increase in salivary leukocytes is not needed to increase Lys.

Sex differences in heat shock protein 72 expression in peripheral blood mononuclear cells to acute exercise in the heat.

Background: Heat shock protein 72 (Hsp72) is responsible for maintaining critical cellular function during heat stress. Hsp72 confers thermotolerance and may play a role in heat acclimation. Animal research suggests a difference between sexes in Hsp72 expression in response to exercise, however, human data is lacking. Objectives: To determine sex differences in intracellular heat shock protein 72 (Hsp72) following exercise in the heat. Patients and Methods: Nine non-heat acclimated women with normal menstrual cycles (VO2pk 58 ± 5 mL.kgFFM-1.min-1) and nine non-heat acclimated men (VO2pk 60 ± 7 ml.kgFFM-1.min-1) completed 2 treadmill bouts at 60% VO2pk for 60 min in a 42°C, 20% RH environment. Women were tested in follicular (fol) and luteal (lut) phases. The duplicate trials were separated by 12 days for men and women. Blood samples were drawn pre, immediately post, 1, and 4 hrs post-exercise. Results: Men and women differed in their Hsp72 response after exercise (time X sex X trial interaction; P < 0.05). Men increased Hsp72 after exercise more than women. Both men and women produced less Hsp72 during trial 2 compared to trial 1. Estrogen (r = 0.24; P > 0.05) and progesterone (r = 0.27, P > 0.05) concentrations were not correlated with Hsp72. Conclusion: Our findings suggest that men and women differ in their cellular stress response. Men up-regulated Hsp72 after a single bout of exercise in the heat, which persists for 12 days, suggesting an accumulation of Hsp72 which may lead to acquired cellular thermotolerance.

Interaction Between Race and Weight Loss Intervention Strategy: Effect on Markers of Inflammation and Fat Distribution in Overweight Women

TO THE EDITOR: I am writing regarding the articles by Fisher et al. titled “Markers of Inflammation and Fat Distribution Following Weight Loss in African-American and White Women” (1) and “Effect of Diet With and Without Exercise Training on Markers of Inflammation and Fat Distribution in Overweight Women” (2), which appeared in the April and June (2011) issues of this journal, respectively. The major conclusion of the first study was that all markers of inflammation (tumor necrosis factor-α, soluble tumor necrosis factor receptor-1, soluble tumor necrosis factor receptor II, interleukin-6, C-reactive protein) decreased with weight loss in whites, whereas only interleukin-6 and C-reactive protein decreased following weight loss in African Americans. Differences in tumor necrosis factor-α family members were attributed to higher intra-abdominal adipose tissue in whites at baseline, which allowed for a greater reduction of intra-abdominal adipose tissue during the weight loss intervention. The major conclusion of the second study was that diet alone (DIET), diet and aerobic exercise (AEROBIC), and diet and resistance training (RESISTANCE) all evoke similar reductions in markers of inflammation (tumor necrosis factor-α, soluble tumor necrosis factor receptor-1, soluble tumor necrosis factor receptor II, interleukin-6, C-reactive protein); i.e., when added to a weight loss regimen, exercise does not reduce inflammation beyond the effect of weight loss alone. The effects of weight loss in the second study were also attributed to changes in intraabdominal adipose tissue. The identical total N-size (Supplementary Figure S1) and overlapping language in the Methods section of these papers suggest both articles stemmed from the same intervention study. Is this true? If so, did the authors examine the interaction of race and exercise training regimen, which could have confounded the interpretation of both articles? Take, for example, the ~1 kg increase in lean mass reported in the 54 subjects who underwent RESISTANCE (2). Referencing prior work by the same authors, which employed an identical intervention strategy, we note that African-American women experience superior lean mass gains in response to RESISTANCE (vs. whites) (3). I wonder if this might account for the “tendency for African-Americans to show a preservation of lean mass with weight loss, whereas whites tended to show a decrease” (1). If more African Americans were enrolled in RESISTANCE, this might also account for the visually (but not statistically) lower values for intra-abdominal adipose tissue and tumor necrosis factor-α in RESISTANCE at baseline (2). Readers of this journal would likely benefit from knowing the distribution of African Americans and whites in the DIET, AEROBIC, and RESISTANCE intervention groups. I am also intrigued by the incredible preservation of lean mass reported in both papers; subjects either maintained or gained lean mass while simultaneously shedding ~12 kg, or ~20% of their total body fat (2). As an exercise physiologist who also moonlights in the weight loss arena, my clients constantly ask why their loss of fat is accompanied by some loss of lean mass; I respond by (i) explaining the importance of the rate of weight loss and (ii) advising my clients to add resistance training to their weight loss regimen. What puzzles me is that my clients are reducing their intake by a mere ~500 kcal/day (or ~25–30% caloric restriction), and still experiencing some loss of lean mass, while these subjects are maintaining or improving lean mass despite a much greater reduction in intake (~1,150 kcal or ~55–65% caloric restriction) (4). I first assumed this difference was due to the resistance training regimen in

Functional Respiratory Muscle Training During Endurance Exercise Causes Modest Hypoxemia but Overall is Well Tolerated.

Abstract Granados, J, Gillum, TL, Castillo, W, Christmas, KM, and Kuennen, MR. “Functional” respiratory muscle training during endurance exercise causes modest hypoxemia but overall is well tolerated. J Strength Cond Res 30(3): 755–762, 2016—A novel commercial training mask purportedly allows for combined respiratory muscle training and altitude exposure during exercise. We examined the masks ability to deliver on this claim. Ten men completed three bouts of treadmill exercise at a matched workload (60%V[Combining Dot Above]O2peak) in a controlled laboratory environment. During exercise, the mask was worn in 2 manufacturer-defined settings (9,000 ft [9K] and 15,000 ft [15K]) and a Sham configuration (∼3,500 ft). Ventilation (VE), tidal volume (VT), respiratory rate (RR), expired oxygen (FEO2) and carbon dioxide (FECO2), peripheral oxygen saturation (SPO2), heart rate, and RPE were measured each minute during exercise, and subjects completed the Beck Anxiety Inventory (BAI) immediately after. The mask caused a reduction in VE of ∼20L/min in both the 9K and 15K configurations (p < 0.001). This was due to a reduction in RR of ∼10 b·min−1, but not VT, which was elevated by ∼250 ml (p < 0.001). FEO2 was reduced and FECO2 was elevated above Sham in both 9K and 15K (p < 0.001). V[Combining Dot Above]O2 was not different across conditions (p = 0.210), but V[Combining Dot Above]CO2 trended lower at 9K (p = 0.093) and was reduced at 15K (p = 0.016). VE/V[Combining Dot Above]O2 was 18.3% lower than Sham at 9K and 19.2% lower at 15K. VE/V[Combining Dot Above]CO2 was 16.2% lower than Sham at 9K and 18.8% lower at 15K (all p < 0.001). Heart rate increased with exercise (p < 0.001) but was not different among conditions (p = 0.285). SPO2 averaged 94% in Sham, 91% at 9K, and 89% at 15K (p < 0.001). RPE and BAI were also higher in 9K and 15K (p < 0.010), but there was no difference among mask conditions. The training mask caused inadequate hyperventilation that led to arterial hypoxemia and psychological discomfort, but the magnitude of these responses were small and they did not vary across mask configurations.

Exercise At Simulated Altitude Increases Gastrointestinal Barrier Damage And Promotes Leukocyte Activation: 1378 Board #186 May 31 8

gastrointestinal barrier, activates leukocytes, and promotes inflammation. METHODS: Subjects (N = 5) completed two 60 min bouts of matched-workload treadmill exercise (65% VO2max). One under control conditions (Normoxia, FIO2 = 20.9%) and the other at ~4000 m of simulated altitude (Hypoxia, FIO2 = 13.5%). Pulse oximetry was used to measure peripheral oxygen saturation (SpO2) and near-infrared spectroscopy was used to measure absolute tissue saturation (StO2) at 5 min intervals throughout exercise. Fatty acid-binding protein (I-FABP), markers of leukocyte activation (CD14, ICAM-1, IL-8, MCP-1, MPO), and cytokines (TNFα, IL-1β, IL-6, IL-10, IL-12) were measured in plasma samples that were collected Pre, Post, 1hr-Post, and 4hr-Post exercise. Data were analyzed with 2-Way (Condition x Time) RM ANOVAs with significance set at p ≤ 0.05. Post hocs (Newman-Keuls) were run where appropriate. RESULTS: Significant reductions in SpO2 and StO2 were shown during exercise at simulated altitude [(SpO2: Hypoxia = 79± 1% vs Normoxia = 94± 0.5%, p = 0.03) (StO2: Hypoxia = 61± 2 vs Normoxia = 69± 2, p < 0.01)]. A significant interaction effect was shown for I-FABP (p = 0.05), with post hoc analysis indicating I-FABP increased more from Pre to Post in Hypoxia (112%) than in Normoxia (30%). IL-8 increased more from Pre to Post (60%) and 1hr-Post (83%) in Hypoxia than in Normoxia (33% & 57%, respectively). Significant main effects were also shown for IL-6, ICAM-1, CD14, and MCP-1. All were higher in Hypoxia (p ≤ 0.05). MPO increased at Post in Normoxia (121%, p = 0.05) but did not increase until 1hr-Post in Hypoxia (129%, p = 0.02). CONCLUSIONS: Preliminary data suggest exercise at altitude may increase gastrointestinal barrier damage and leukocyte activation, as indicated by higher levels of I-FABP, IL-8, and MCP-1. Increased CD14 and ICAM-1 suggest TLR4-mediated inflammatory signaling may also be elevated, but the delayed increase in MPO following exercise at altitude warrants further investigation.