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Qu, C, Wu, Z, Xu, M, Lorenzo, S, Dong, Y, Wang, Z, Qin, F, and Zhao, J. Cryotherapy on subjective sleep quality, muscle, and inflammatory response in Chinese middle- and long-distance runners after muscle damage. J Strength Cond Res 36(10): 2883-2890, 2022-The purpose of this investigation was to explore the effects of cold-water immersion (CWI), contrast-water therapy (CWT), and whole-body cryotherapy (CRY) on subjective sleep quality, muscle damage markers, and inflammatory markers in middle- and long-distance runners after muscle damage. Twelve male runners from Beijing Sport University completed a muscle damage exercise protocol and were treated with different recovery methods (CWI, CWT, CRY, or control [CON]) immediately after exercise and at 24-, 48-, and 72-h postexercise. The Pittsburgh Sleep Quality Index questionnaire score, lactate dehydrogenase (LDH) activity, myoglobin (Mb) activity, interleukin-6 (IL-6) activity, and soluble intercellular adhesion molecule-1 (sICAM-1) activity were measured at 7 time points (preexercise; immediately postexercise; and at 1-, 24-, 48-, 72-, and 96-h postexercise). Pittsburgh Sleep Quality Index scores indicated that the CRY condition had improved sleep quality compared with the CON and CWI conditions (p0.05). In terms of LDH activity, the CRY and CWT conditions had improved recovery compared with the CON and CWI conditions (p0.05). In terms of Mb activity, the CRY condition exhibited improved recovery compared with that of the CON and CWI conditions (p0.05), and the CWT condition showed better recovery than that of the CON condition (p0.05). In terms of IL-6 activity, the CRY condition showed improved recovery compared with the CWI condition (p0.05). Finally, in terms of sICAM-1 activity, the CRY condition had enhanced recovery compared with the other 3 conditions (p0.05). The results from this study suggest that CRY improves subjective sleep quality and reduces muscle damage and inflammatory responses in middle- and long-distance runners. In addition, CWT reduced muscle damage and inflammatory responses, but its effects on the other parameters were inconclusive.

Context Lower back pain (LBP) is prevalent and is a leading contributor to disease burden worldwide. Osteopathic manipulative treatment (OMT) can alleviate alterations in the body that leads to musculoskeletal disorders such as LBP. Bio-electromagnetic Energy Regulation (BEMER; BEMER International AG), which has also been shown to relieve musculoskeletal pain, is a therapeutic modality that deploys a biorhythmically defined stimulus through a pulsed electromagnetic field (PEMF). Therefore, it is possible that combined OMT and BEMER therapy could reduce low back pain in adults more than the effect of either treatment modality alone. Objectives To investigate the individual and combined effects of OMT and BEMER therapy on LBP in adults. Methods Employees and students at a medical college were recruited to this study by email. Participants were included if they self-reported chronic LBP of 3 months’ duration or longer; participants were excluded if they were experiencing acute LBP of 2 weeks’ duration or less, were currently being treated for LBP, were pregnant, or had a known medical history of several conditions. Ultimately, 40 participants were randomly assigned to four treatment groups: an OMT only, BEMER only, OMT+BEMER, or control (light touch and sham). Treatments were given regularly over a 3 week period. Data on LBP and quality of life were gathered through the Visual Analog Scale (VAS), Short Form 12 item (SF-12) health survey, and Oswestry Low Back Pain Questionnaire/Oswestry Disability Index prior to treatment and immediately after the 3 week intervention protocol. One-way analysis of variance (ANOVA) was performed retrospectively and absolute changes for each participant were calculated. Normal distribution and equal variances were confirmed by Shapiro–Wilk test (p>0.05) and Brown-Forsythe, respectively. Significance was set at p Results Despite a lack of statistical significance between groups, subjective reports of pain reported on the VAS showed a substantial mean percentage decrease (50.8%) from baseline in the OMT+BEMER group, compared with a 10.2% decrease in the OMT-only and 9.8% in BEMER-only groups when comparing the difference in VAS ratings from preintervention to postintervention. Participants also reported in quality of life assessed on the Oswestry Low Back Pain Questionnaire/Oswestry Disability Index, with the OMT+BEMER group showing a decrease of 30.3% in score, the most among all groups. The OMT+BEMER group also reported the greatest improvement in score in the physical component of the SF-12, with an increase of 21.8%. Conclusions The initial data from this study shows a potential additive effect of combination therapy (OMT and BEMER) for management of LBP, though the results did not achieve statistical significance.

Context Standard pulmonary rehabilitation (SPR) does not use osteopathic manipulative treatment (OMT), but OMT has potential to improve lung function and patient perception of breathing. Objective To analyze the immediate effects of OMT and SPR techniques on pulmonary function using spirometry and subjective ratings in young, healthy persons. Methods Participants were healthy students recruited from the Lake Erie College of Osteopathic Medicine-Bradenton and were randomly assigned to either the OMT or SPR group. During the first 4 weeks, each participant in the OMT group received 1 OMT technique (rib raising, doming of the diaphragm, thoracic lymphatic pump, and thoracic high velocity, low amplitude), and each participant in the SPR group received 1 SPR treatment (tapotement, pursed lip breathing, saline nebulizer, and rest) per week. Treatments were then ranked based on positive change in pulmonary function as measured by forced expiratory volume in the first second of expiration (FEV1) and forced vital capacity (FVC). During the fifth week, the OMT group received the 2 highest-ranked OMT techniques, and the SPR group received the 2 highest-ranked SPR treatments. During the sixth week, the OMT group received the highest-ranked OMT and SPR treatment, while the SPR group received the same treatment combination but in the reverse order. Pulmonary function, as measured through FEV1, FVC, and FEV1/FVC, were collected before and after each treatment or treatment combination. Participants subjectively rated change in breathing after each treatment. Results A total of 53 students participated in the study, with 28 in the OMT group and 25 in the SPR group. In the OMT group, rib raising yielded the highest positive mean (SD) change of 0.001 (0.136) L in FEV1 and 0.052 (0.183) L in FVC, followed by lymphatic pump, with a change of 0.080 (0.169) L in FEV1 and −0.031 (0.229) L in FVC. In the SPR group, pursed lip breathing yielded the highest positive mean (SD) change of 0.101 (0.278) L in FEV1 and 0.031 (0.179) L in FVC, followed by tapotement, with a change of 0.045 (0.229) L in FEV1 and 0.061 (0.239) L in FVC. Saline treatment significantly decreased lung function. All other treatments did not result in any significant changes in lung function. Overall, SPR subjective ratings were significantly lower than ratings for both OMT and combination (OMT+SPR) treatments. Conclusions Saline significantly reduced lung function and had low subjective posttreatment ratings in young healthy adults. Additionally, OMT and combination OMT and SPR significantly improved subjective breathing more than SPR alone. Future applications of this study include evaluating OMT and SPR effects on lung function in patients with various pulmonary conditions.

This study aimed to test the hypothesis that different neurotransmitters and hormones are presented at exercise fatigue in hot temperatures with differing relative humidities (RH).Eight trained male athletes performed a graded maximum oxygen consumption (VO2max) test in five different environmental conditions, namely, 21°C/20% RH (Normal), 33°C/20% RH (Hot 20%), 33°C/40% RH (Hot 40%), 33°C/60% RH (Hot 60%), and 33°C/80% RH (Hot 80%). Blood samples were taken pre- and post-exercise and analyzed for noradrenaline (NA), adrenaline (ADR), dopamine (DA), serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), and prolactin (PRL). Weight and oral and skin temperatures were recorded pre- and post-exercise. Heart rate was continuously monitored throughout the exercise.Hot 20%, Hot 40%, and Hot 80% had lower VO2max levels compared with Normal (P0.05). The data pooled from all five conditions indicated that the NA (P0.0001), PRL (P0.0001), 5-HT (P=0.002), 5-HIAA (P=0.029), and DA (P=0.016) levels were affected by exercise. Accordingly, NA level was significantly associated with performance time. However, ADR did not show any significant effect between pre- and post-exercise (P=0.187).The maximal aerobic capacity was impaired in high temperature and most humidity conditions. NA was strongly associated with exercise time, which suggested that exercise duration and intensity had an important influence on NA neurotransmitter level irrespective of the environmental conditions.

The aim of the present study was to determine whether 10 days of repeated local heating could induce peripheral adaptations in the cutaneous vasculature and to investigate potential mechanisms of adaptation. We also assessed maximal forearm blood flow to determine whether repeated local heating affects maximal dilator capacity. Before and after 10 days of heat training consisting of 1-h exposures of the forearm to 42°C water or 32°C water (control) in the contralateral arm (randomized and counterbalanced), we assessed hyperemia to rapid local heating of the skin ( n = 14 recreationally active young subjects). In addition, sequential doses of acetylcholine (ACh, 1 and 10 mM) were infused in a subset of subjects ( n = 7) via microdialysis to study potential nonthermal microvascular adaptations following 10 days of repeated forearm heat training. Skin blood flow was assessed using laser-Doppler flowmetry, and cutaneous vascular conductance (CVC) was calculated as laser-Doppler red blood cell flux divided by mean arterial pressure. Maximal cutaneous vasodilation was achieved by heating the arm in a water-spray device for 45 min and assessed using venous occlusion plethysmography. Forearm vascular conductance (FVC) was calculated as forearm blood flow divided by mean arterial pressure. Repeated forearm heating did not increase plateau percent maximal CVC (CVCmax) responses to local heating (89 ± 3 vs. 89 ± 2% CVCmax, P = 0.19), 1 mM ACh (43 ± 9 vs. 53 ± 7% CVCmax, P = 0.76), or 10 mM ACh (61 ± 9 vs. 85 ± 7% CVCmax, P = 0.37, by 2-way repeated-measures ANOVA). There was a main effect of time at 10 mM ACh ( P = 0.03). Maximal FVC remained unchanged (0.12 ± 0.02 vs. 0.14 ± 0.02 FVC, P = 0.30). No differences were observed in the control arm. Ten days of repeated forearm heating in recreationally active young adults did not improve the microvascular responsiveness to ACh or local heating. NEW & NOTEWORTHY We show for the first time that 10 days of repeated forearm heating is not sufficient to improve cutaneous vascular responsiveness in recreationally active young adults. In addition, this is the first study to investigate cutaneous cholinergic sensitivity and forearm blood flow following repeated local heat exposure. Our data add to the limited studies regarding repeated local heating of the cutaneous vasculature.

The quantification and interpretation of cardiorespiratory fitness (CRF) in obesity is important for adequately assessing cardiovascular conditioning, underlying comorbidities, and properly evaluating disease risk. We retrospectively compared peak oxygen uptake (VO(2)peak) (ie, CRF) in absolute terms, and relative terms (% predicted) using three currently suggested prediction equations (Equations R, W, and G).There were 19 nonobese and 66 obese participants. Subjects underwent hydrostatic weighing and incremental cycling to exhaustion. Subject characteristics were analyzed by independent t test, and % predicted VO(2)peak by a two-way analysis of variance (group and equation) with repeated measures on one factor (equation).VO(2)peak (L/min) was not different between nonobese and obese adults (2.35 ± 0.80 [SD] vs 2.39 ± 0.68 L/min). VO(2)peak was higher (P.02) relative to body mass and lean body mass in the nonobese (34 ± 8 mL/min/kg vs 22 ± 5 mL/min/kg, 42 ± 9 mL/min/lean body mass vs 37 ± 6 mL/min/lean body mass). Cardiorespiratory fitness assessed as % predicted was not different in the nonobese and obese (91% ± 17% predicted vs 95% ± 15% predicted) using Equation R, while using Equation W and G, CRF was lower (P.05) but within normal limits in the obese (94 ± 15 vs 87 ± 11; 101% ± 17% predicted vs 90% ± 12% predicted, respectively), depending somewhat on sex.Traditional methods of reporting VO(2)peak do not allow adequate assessment and quantification of CRF in obese adults. Predicted VO(2)peak does allow a normalized evaluation of CRF in the obese, although care must be taken in selecting the most appropriate prediction equation, especially in women. In general, otherwise healthy obese are not grossly deconditioned as is commonly believed, although CRF may be slightly higher in nonobese subjects depending on the uniqueness of the prediction equation.

The relationship between exercise performance and lactate and ventilatory thresholds under two distinct environmental conditions is unknown. We examined the relationships between six lactate threshold methods (blood- and ventilation-based) and exercise performance in cyclists in hot and cool environments. Twelve cyclists performed a lactate threshold test, a maximal O2 uptake (V̇o2max) test, and a 1-h time trial in hot (38°C) and cool (13°C) conditions, before and after heat acclimation. Eight control subjects completed the same tests before and after 10 days of identical exercise in a cool environment. The highest correlations were observed with the blood-based lactate indexes; however, even the indirect ventilation-based indexes were well correlated with mean power during the time trial. Averaged bias was 15.4 ± 3.6 W higher for the ventilation- than the blood-based measures ( P < 0.05). The bias of blood-based measures in the hot condition was increased: the time trial was overestimated by 37.7 ± 3.6 W compared with only 24.1 ± 3.2 W in the cool condition ( P < 0.05). Acclimation had no effect on the bias of the blood-based indexes ( P = 0.51) but exacerbated the overestimation by some ventilation-based indexes by an additional 34.5 ± 14.1 W ( P < 0.05). Blood-based methods to determine lactate threshold show less bias and smaller variance than ventilation-based methods when predicting time-trial performance in cool environments. Of the blood-based methods, the inflection point between steady-state lactate and rising lactate (INFL) was the best method to predict time-trial performance. Lastly, in the hot condition, ventilation-based predictions are less accurate after heat acclimation, while blood-based predictions remain valid in both environments after heat acclimation.

The aim of this study was to explore heat acclimation effects on cutaneous vascular responses and sweating to local ACh infusions and local heating. We also sought to examine whether heat acclimation altered maximal skin blood flow. ACh (1, 10, and 100 mM) was infused in 20 highly trained cyclists via microdialysis before and after a 10-day heat acclimation program [two 45-min exercise bouts at 50% maximal O2 uptake (V̇o2max) in 40°C ( n = 12)] or control conditions [two 45-min exercise bouts at 50% V̇o2max in 13°C ( n = 8)]. Skin blood flow was monitored via laser-Doppler flowmetry (LDF), and cutaneous vascular conductance (CVC) was calculated as LDF ÷ mean arterial pressure. Sweat rate was measured by resistance hygrometry. Maximal brachial artery blood flow (forearm blood flow) was obtained by heating the contralateral forearm in a water spray device and measured by Doppler ultrasound. Heat acclimation increased %CVCmax responses to 1, 10, and 100 mM ACh (43.5 ± 3.4 vs. 52.6 ± 2.6% CVCmax, 67.7 ± 3.4 vs. 78.0 ± 3.0% CVCmax, and 81.0 ± 3.8 vs. 88.5 ± 1.1% CVCmax, respectively, all P < 0.05). Maximal forearm blood flow remained unchanged after heat acclimation (290.9 ± 12.7 vs. 269.9 ± 23.6 ml/min). The experimental group showed significant increases in sweating responses to 10 and 100 mM ACh (0.21 ± 0.03 vs. 0.31 ± 0.03 mg·cm−2·min−1 and 0.45 ± 0.05 vs. 0.67 ± 0.06 mg·cm−2·min−1, respectively, all P < 0.05), but not to 1 mM ACh (0.13 ± 0.02 vs. 0.18 ± 0.02 mg·cm−2·min−1, P = 0.147). No differences in any of the variables were found in the control group. Heat acclimation in highly trained subjects induced local adaptations within the skin microcirculation and sweat gland apparatus. Furthermore, maximal skin blood flow was not altered by heat acclimation, demonstrating that the observed changes were attributable to improvement in cutaneous vascular function and not to structural changes that limit maximal vasodilator capacity.

Attenuation correction (AC) for myocardial perfusion SPECT (MPS) had not been evaluated separately in women despite specific considerations in this group because of breast photon attenuation. We aimed to evaluate the performance of AC in women by using automated quantitative analysis of MPS to avoid any bias. Methods: Consecutive female patients—134 with a low likelihood (LLk) of coronary artery disease (CAD) and 114 with coronary angiography performed within less than 3 mo of MPS—who were referred for rest–stress electrocardiography-gated 99mTc-sestamibi MPS with AC were considered. Imaging data were evaluated for contour quality control. An additional 50 LLk studies in women were used to create equivalent normal limits for studies with AC and with no correction (NC). An experienced technologist unaware of the angiography and other results performed the contour quality control. All other processing was performed in a fully automated manner. Quantitative analysis was performed with the Cedars-Sinai myocardial perfusion analysis package. All automated segmental analyses were performed with the 17-segment, 5-point American Heart Association model. Summed stress scores (SSS) of ≥3 were considered abnormal. Results: CAD (≥70% stenosis) was present in 69 of 114 patients (60%). The normalcy rates were 93% for both NC and AC studies. The SSS for patients with CAD and without CAD for NC versus AC were 10.0 ± 9.0 (mean ± SD) versus 10.2 ± 8.5 and 1.6 ± 2.3 versus 1.8 ± 2.5, respectively; P was not significant (NS) for all comparisons of NC versus AC. The SSS for LLk patients for NC versus AC were 0.51 ± 1.0 versus 0.6 ± 1.1, respectively; P was NS. The specificity for both NC and AC was 73%. The sensitivities for NC and AC were 80% and 81%, respectively, and the accuracies for NC and AC were 77% and 78%, respectively; P was NS for both comparisons. Conclusion: There are no significant diagnostic differences between automated quantitative MPS analyses performed in studies processed with and without AC in women.

Reactive hyperaemia is the increase in blood flow following arterial occlusion. The exact mechanisms mediating this response in skin are not fully understood. The purpose of this study was to investigate the individual and combined contributions of (1) sensory nerves and large-conductance calcium activated potassium (BKCa) channels, and (2) nitric oxide (NO) and prostanoids to cutaneous reactive hyperaemia. Laser-Doppler flowmetry was used to measure skin blood flow in a total of 18 subjects. Peak blood flow (BF) was defined as the highest blood flow value after release of the pressure cuff. Total hyperaemic response was calculated by taking the area under the curve (AUC) of the hyperaemic response minus baseline. Infusates were perfused through forearm skin using microdialysis in four sites. In the sensory nerve/BKCa protocol: (1) EMLA cream (EMLA, applied topically to skin surface), (2) tetraethylammonium (TEA), (3) EMLA + TEA (Combo), and (4) Ringer solution (Control). In the prostanoid/NO protocol: (1) ketorolac (Keto), (2) NG-nitro-l-arginine methyl ester (L-NAME), (3) Keto + l-NAME (Combo), and (4) Ringer solution (Control). CVC was calculated as flux/mean arterial pressure and normalized to maximal flow. Hyperaemic responses in Control (1389 +/- 794%CVC max s) were significantly greater compared to TEA, EMLA and Combo sites (TEA, 630 +/- 512, P = 0.003; EMLA, 421 +/- 216, P < 0.001; Combo, 201 +/- 200, P < 0.001%CVC max s). Furthermore, AUC in Combo (Keto + l-NAME) site was significantly greater than Control (4109 +/- 2777 versus 1295 +/- 368%CVC max s). These data suggest (1) sensory nerves and BKCa channels play major roles in the EDHF component of reactive hyperaemia and appear to work partly independent of each other, and (2) the COX pathway does not appear to have a vasodilatory role in cutaneous reactive hyperaemia.

Post-occlusive and local thermal hyperemia are currently used as integrated tests to study microvascular function in microvascular diseases. However, further pathophysiological insight would require its association with microdialysis. The major limitation remains the microinvasive approach as local anaesthesia prior to fiber insertion could lead to confounding effects. The objective of our study was to determine whether EMLA® cream treatment, applied for 20 min, 40 or 60 min, significantly decreases the pain related to intradermal needle insertions, while not decreasing the microvascular response to post-occlusive and thermal hyperemia 2 h after cream removal. EMLA® cream, when applied during 40 min, induces a significant 75% decrease in the pain following intradermal needle insertion, while not modifying skin post-occlusive and thermal hyperemia 2 h after cream removal. Therefore, we recommend its use in such conditions before performing microdialysis coupled with laser Doppler flowmetry in cohort studies aimed at studying microvascular dysfunction in patients with microvascular diseases.

Background Alterations in respiratory mechanics predispose healthy obese individuals to low lung volume breathing, which places them at risk of developing expiratory flow limitation (EFL). The high ventilatory demand in endurance-trained obese adults further increases their risk of developing EFL and increases their work of breathing. The objective of this study was to investigate the prevalence and magnitude of EFL in fit obese (FO) adults via measurements of breathing mechanics and ventilatory dynamics during exercise. Methods Ten (seven women and three men) FO (mean ± SD, 38 ± 5 years, 38% ± 5% body fat) and 10 (seven women and three men) control obese (CO) (38 ± 5 years, 39% ± 5% body fat) subjects underwent hydrostatic weighing, pulmonary function testing, cycle exercise testing, and the determination of the oxygen cost of breathing during eucapnic voluntary hyperpnea. Results There were no differences in functional residual capacity (43% ± 6% vs 40% ± 9% total lung capacity [TLC]), residual volume (21% ± 4% vs 21% ± 4% TLC), or FVC (111% ± 13% vs 104% ± 15% predicted) between FO and CO subjects, respectively. FO subjects had higher FEV 1 (111% ± 13% vs 99% ± 11% predicted), TLC (106% ± 14% vs 94% ± 7% predicted), peak expiratory flow (123% ± 14% vs 106% ± 13% predicted), and maximal voluntary ventilation (128% ± 15% vs 106% ± 13% predicted) than did CO subjects. Peak oxygen uptake (129% ± 16% vs 86% ± 15% predicted), minute ventilation (128 ± 35 L/min vs 92 ± 25 L/min), and work rate (229 ± 54 W vs 166 ± 55 W) were higher in FO subjects. Mean inspiratory (4.65 ± 1.09 L/s vs 3.06 ± 1.21 L/s) and expiratory (4.15 ± 0.95 L/s vs 2.98 ± 0.76L/s) flows were greater in FO subjects, which yielded a greater breathing frequency (51 ± 8 breaths/min vs 41 ± 10 breaths/min) at peak exercise in FO subjects. Mechanical ventilatory constraints in FO subjects were similar to those in CO subjects despite the greater ventilatory demand in FO subjects. Conclusion FO individuals achieve high ventilations by increasing breathing frequency, matching the elevated metabolic demand associated with high fitness. They do this without developing meaningful ventilatory constraints. Therefore, endurance-trained obese individuals with higher lung function are not limited by breathing mechanics during peak exercise, which may allow healthy obese adults to participate in vigorous exercise training.

Obesity affects lung function and gas exchange and imposes mechanical ventilatory limitations during exercise that could disrupt the predictability of Pa(CO(2)) from end-tidal P(CO(2)) (P(ETCO(2))), an important clinical tool for assessing gas exchange efficiency during exercise testing. Pa(CO(2)) has been estimated during exercise with good accuracy in normal-weight individuals by using a correction equation developed by Jones and colleagues (P(JCO(2)) = 5.5 + 0.9 x P(ETCO(2)) – 2.1 x tidal volume). The purpose of this project was to determine the accuracy of Pa(CO(2)) estimations from P(ETCO(2)) and P(JCO(2)) values at rest and at submaximal and peak exercise in morbidly obese adults.Pa(CO(2)) and P(ETCO(2)) values from 37 obese adults (22 women, 15 men; age, 39 ± 9 y; BMI, 49 ± 7; [mean ± SD]) were evaluated. Subjects underwent ramped cardiopulmonary exercise testing to volitional exhaustion. P(ETCO(2)) was determined from expired gases simultaneously with temperature-corrected arterial blood gases (radial arterial catheter) at rest, every minute during exercise, and at peak exercise. Data were analyzed using paired t tests.P(ETCO(2)) was not significantly different from Pa(CO(2)) at rest (P(ETCO(2)) = 37 ± 3 mm Hg vs Pa(CO(2)) = 38 ± 3 mm Hg, P = .14). However, during exercise, P(ETCO(2)) was significantly higher than Pa(CO(2)) (submaximal: 42 ± 4 vs 40 ± 3, P.001; peak: 40 ± 4 vs 37 ± 4, P.001, respectively). Jones’ equation successfully corrected P(ETCO(2)), such that P(JCO(2)) was not significantly different from Pa(CO(2)) (submax: P(JCO(2)) = 40 ± 3, P = .650; peak: 37 ± 4, P = .065).P(JCO(2)) provides a better estimate of Pa(CO(2)) than P(ETCO(2)) during submaximal exercise and at peak exercise, whereas at rest both yield reasonable estimates in morbidly obese individuals. Clinicians and physiologists can obtain accurate estimations of Pa(CO(2)) in morbidly obese individuals by using P(JCO(2)).

Although it has been reported that the work of breathing may be higher in women, inconsistencies among studies leaves this important question unresolved. Also, the association between the oxygen cost of breathing and rating of perceived breathlessness (RPB) during exercise has not been examined between women and men.This study aimed to measure oxygen cost of breathing during eucapnic voluntary hyperpnea and RPB (Borg 0-10 scale) during 6 min of constant work rate cycling at 60 and 90 W, respectively, in healthy, nonobese women and men.A total of 9 women (27 yr, body mass index = 21 kg·m(-2)) and 10 men (29 yr, body mass index = 25 kg·m(-2)) participated. All subjects underwent pulmonary function testing, exercise cycling, and determination of oxygen cost of breathing during eucapnic voluntary hyperpnea. Oxygen cost of breathing was obtained from the slope of the oxygen uptake (mL·min(-1)) and ventilation (L·min(-1)) relationship. RPB and cardiorespiratory measures were collected during minute 6 of the exercise. Data were analyzed by independent t-test and regression analysis.Age and pulmonary function were similar between the nonobese women and men. Oxygen cost of breathing was similar between the nonobese women (1.17 ± 0.26 mL·L(-1)) and men (1.21 ± 0.42 mL·(-1)L). RPB during exercise was similar between the women (2.1 ± 1.3) and men (2.6 ± 1.2) and was correlated (P0.05) with relative oxygen uptake (r = 0.55) but not the oxygen cost of breathing.In nonobese women and men, oxygen cost of breathing is not different over the ventilatory ranges studied and RPB is similar at the same relative exercise intensity. In addition, the oxygen cost of breathing was not associated with RPB during constant work rate exercise.

The Fick principle (cardiac output [Q(c)] = oxygen uptake [Vo(2)]/arteriovenous oxygen difference) can be used to calculate Q(c), with VO(2) frequently estimated by derived equations. To compare the accuracy of measured versus estimated VO(2), data were analyzed from 2 studies in which VO(2) at rest was measured using the Douglas bag technique. One study comprised adults with diabetes, and the other was an exercise study of healthy adults. VO(2) at rest was estimated as VO(2) (ml/min) = 125 ml/min/m(2) × body surface area (m(2)), with sensitivity analyses evaluating 2 other commonly used equations. Mean absolute difference (milliliters per minute) and ordinary least products regression were used to assess agreement between measured and estimated VO(2). Overall, mean measured versus estimated VO(2) differed significantly (307.2 ± 75.2 vs 259.9 ± 36.7 ml/min, p0.0001), with a mean absolute difference of 52.9 ± 43.2 ml/min (p0.0001); 20% of the estimates differed by25% from the measured VO(2). Mean absolute difference increased from 36.7 ml/min in the lowest body mass index group (25 kg/m(2)) to 91.7 ml/min in the highest group (≥40 kg/m(2)) (p for trend = 0.001) and was significantly higher in men than in women (65.6 vs 33.9 ml/min, p = 0.001); error was similar by median-split age (p = 0.65) and race (p = 0.34). Similar results were obtained when evaluating each of the other 2 estimating equations. Estimation of VO(2) at rest is inaccurate, especially in men and with increasing adiposity. In conclusion, when clinical hemodynamic assessment is performed, VO(2) should be measured, not estimated.

This study examined the impact of heat acclimation on improving exercise performance in cool and hot environments. Twelve trained cyclists performed tests of maximal aerobic power (V̇o2max), time-trial performance, and lactate threshold, in both cool [13°C, 30% relative humidity (RH)] and hot (38°C, 30% RH) environments before and after a 10-day heat acclimation (∼50% V̇o2max in 40°C) program. The hot and cool condition V̇o2max and lactate threshold tests were both preceded by either warm (41°C) water or thermoneutral (34°C) water immersion to induce hyperthermia (0.8–1.0°C) or sustain normothermia, respectively. Eight matched control subjects completed the same exercise tests in the same environments before and after 10 days of identical exercise in a cool (13°C) environment. Heat acclimation increased V̇o2max by 5% in cool (66.8 ± 2.1 vs. 70.2 ± 2.3 ml·kg−1·min−1, P = 0.004) and by 8% in hot (55.1 ± 2.5 vs. 59.6 ± 2.0 ml·kg−1·min−1, P = 0.007) conditions. Heat acclimation improved time-trial performance by 6% in cool (879.8 ± 48.5 vs. 934.7 ± 50.9 kJ, P = 0.005) and by 8% in hot (718.7 ± 42.3 vs. 776.2 ± 50.9 kJ, P = 0.014) conditions. Heat acclimation increased power output at lactate threshold by 5% in cool (3.88 ± 0.82 vs. 4.09 ± 0.76 W/kg, P = 0.002) and by 5% in hot (3.45 ± 0.80 vs. 3.60 ± 0.79 W/kg, P < 0.001) conditions. Heat acclimation increased plasma volume (6.5 ± 1.5%) and maximal cardiac output in cool and hot conditions (9.1 ± 3.4% and 4.5 ± 4.6%, respectively). The control group had no changes in V̇o2max, time-trial performance, lactate threshold, or any physiological parameters. These data demonstrate that heat acclimation improves aerobic exercise performance in temperate-cool conditions and provide the scientific basis for employing heat acclimation to augment physical training programs.

We aimed to compare the automation and diagnostic performance in the detection of coronary artery disease (CAD) of the 4DMSPECT (4DM), Emory Cardiac Toolbox (EMO), and QPS systems for automated quantification of myocardial perfusion.We studied 328 patients referred for rest/stress Tc-99m sestamibi imaging, 140 low-likelihood patients and 188 with angiography. Contours were corrected when necessary. All other processing was fully automated. A 17-segment analysis was performed, and a summed stress score (SSS)or =4 was considered abnormal. The average SSSs (+/-SD) for 4DM, EMO, and QPS were 10.5 +/- 9.4, 11.1 +/- 8.3, and 10.1 +/- 8.9, respectively (P = .02 for QPS versus EMO). The receiver operator characteristics areas-under-the-curve for the detection of CAD (+/-SEM) were 0.84 +/- 0.03, 0.76 +/- 0.04, and 0.88 +/- 0.03 for 4DM, EMO, and QPS, respectively (P = .001 for QPS versus EMO, and P = .03 for 4DM versus EMO). Normalcy rate was higher for QPS and 4DM versus EMO, at 91% and 94% versus 77%, respectively (P = .02). Sensitivity was higher for QPS (87%) versus 4DM (80%) (P = .045). Specificity was higher for QPS (71%) versus EMO (49%) (P = .01). The accuracy rate was higher for QPS versus 4DM and EMO, at 83% versus 77% and 76%, respectively (P = .05).There are differences in myocardial-perfusion quantification, diagnostic performance, and degree of automation of software packages.

We aimed to compare normal limits and the detection of coronary artery disease (CAD) with attenuation-corrected (AC) and non-attenuation-corrected (NC) myocardial perfusion single photon emission computed tomography (MPS) by use of a recently improved automated quantification technique.We acquired 415 rest/stress technetium 99m MPS studies on a Vertex dual-detector camera with a gadolinium 153 line source (Vantage Pro). Gender-specific NC, AC, and gender-combined AC normal limits were created from rest/stress images of 50 women and 50 men with a low likelihood of CAD (5%) and a median body mass index (BMI) of 30 kg/m2 in each gender group. BMI-specific normal limits (30 kg/m2 andor = 30 kg/m2) were also compared. Total perfusion deficit and 17-segment summed scores in 174 patients were compared with angiography, and normalcy rates were established from 141 studies of low-likelihood patients. There were no differences between low-BMI and high-BMI normal limits for AC or NC studies. Male and female normal limits differed in 12 of 17 segments for NC stress studies and in 3 of 17 segments for AC stress studies (P.01). The sensitivity, specificity, and normalcy rates for stenoses with 70% narrowing or greater were 89%, 73%, and 91%, respectively, for NC studies and 87%, 80%, and 95%, respectively, for AC studies (P = not significant).Automated detection of CAD by AC and NC MPS demonstrated similar sensitivity, specificity, and normalcy rates. Some gender differences were noted for AC normal limits.

Previous studies suggest that the maximum oxygen uptake (VO2max) and the Wingate anaerobic test performances are decreased in hot environments, but it is unknown whether humidity changes in a hot environment further affect the results of the VO2max and Wingate anaerobic test. Nine male athletes performed VO2max and Wingate anaerobic tests under three environmental conditions: (1) 21 °C/20% relative humidity (R.H.) (control); (2) 33 °C/20% R.H. (hot–dry); and (3) 33 °C/80% R.H. (hot–wet). The participants' weight, oral temperature, and skin temperature were recorded pre-exercise and postexercise. The heart rate was monitored continuously throughout the exercise. Compared to the control condition, the hot–dry and the hot–wet conditions had lower VO2max values (control at 3779.0 ± 234.3 mL/min vs. hot–dry at 3528.2 ± 467.4 mL/min and hot–wet at 3595.9 ± 274.6 mL/min; p