Diagnostic value of dynamic contrast-enhanced CT with perfusion imaging in the quantitative assessment of tumor response to sorafenib in patients with advanced hepatocellular carcinoma: A feasibility study

PurposeTo investigate the feasibility of perfusion-CT (p-CT) measurements in quantitative assessment of hemodynamic changes related to sorafenib in patients with advanced hepatocellular carcinoma (HCC).Materials and methodsTwenty-two patients with advanced HCC underwent p-CT study (256-MDCT scanner) before and 2 months after sorafenib administration. Dedicated perfusion software generated a quantitative map of arterial and portal perfusion and calculated the following perfusion parameters in target liver lesion: hepatic perfusion (HP), time-to-peak (TTP), blood volume (BV), arterial perfusion (AP), and hepatic perfusion index (HPI). After the follow-up scan, patients were categorized as responders and non-responders, according to mRECIST. Perfusion values were analyzed and compared in HCC lesions and in the cirrhotic parenchyma (n = 22), such as between baseline and follow-up in progressors and non-progressors.ResultsBefore treatment, all mean perfusion values were significantly higher in HCC lesions than in the cirrhotic parenchyma (HP 47.8 ± 17.2 vs 13.3 ± 6.3 mL/s per 100 g; AP 47.9 ± 18.1 vs 12.9 ± 10.7 mL/s; p < 0.001). The group that responded to sorafenib (n = 17) showed a significant reduction of values in HCC target lesions after therapy (HP 29.2 ± 23.3 vs 48.1 ± 15.1; AP 29.4 ± 24.6 vs 49.2 ± 17.4; p < 0.01), in comparison with the non-responder group (n = 5) that demonstrated no significant variation before and after treatment of HP (46.9 ± 25.1 vs 46.7 ± 24.1) and AP (43.4 ± 21.7 vs 43.5 ± 24.6). Among the responder group, HP percentage variation (Δ) in target lesions, during treatment, showed a significantly different (p = 0.04) ΔHP in the group with complete response (79%) compared to the group with partial response or stable disease (16%).Conclusionsp-CT technique can be used for HCC quantitative assessment of changes related to anti-angiogenic therapy. Identification of response predictors might help clinicians in selection of patients who may benefit from targeted-therapy allowing for optimization of individualized treatment.     

Difference in diaphragmatic motion during tidal breathing in a standing position between COPD patients and normal subjects: Time-resolved quantitative evaluation using dynamic chest radiography with flat panel detector system (“dynamic X-ray phrenicography”)

ObjectivesTo quantitatively compare diaphragmatic motion during tidal breathing in a standing position between chronic obstructive pulmonary disease (COPD) patients and normal subjects using dynamic chest radiography.Materials and methodsThirty-nine COPD patients (35 males; age, 71.3 ± 8.4 years) and 47 normal subjects (non-smoker healthy volunteers) (20 males; age, 54.8 ± 9.8 years) underwent sequential chest radiographs during tidal breathing using dynamic chest radiography with a flat panel detector system. We evaluated the excursions and peak motion speeds of the diaphragms. The results were analyzed using an unpaired t-test and a multiple linear regression model.ResultsThe excursions of the diaphragms in COPD patients were significantly larger than those in normal subjects (right, 14.7 ± 5.5 mm vs. 10.2 ± 3.7 mm, respectively, P < 0.001; left, 17.2 ± 4.9 mm vs. 14.9 ± 4.2 mm, respectively, P = 0.022). Peak motion speeds in inspiratory phase were significantly faster in COPD patients compared to normal subjects (right, 16.3 ± 5.0 mm/s vs. 11.8 ± 4.2 mm/s, respectively, P < 0.001; left, 18.9 ± 4.9 mm/s vs. 16.7 ± 4.0 mm/s, respectively, P = 0.022). The multivariate analysis demonstrated that having COPD and higher body mass index were independently associated with increased excursions of the bilateral diaphragm (all P < 0.05), after adjusting for other clinical variables.ConclusionsTime-resolved quantitative evaluation of the diaphragm using dynamic chest radiography demonstrated that the diaphragmatic motion during tidal breathing in a standing position is larger and faster in COPD patients than in normal subjects.     

Respiration-induced Deformations of the Superior Mesenteric and Renal Arteries in Patients with Abdominal Aortic Aneurysms

PurposeTo quantify respiration-induced deformations of the superior mesenteric artery (SMA), left renal artery (LRA), and right renal artery (RRA) in patients with small abdominal aortic aneurysms (AAAs).Materials and MethodsSixteen men with AAAs (age 73 y ± 7) were imaged with contrast-enhanced magnetic resonance angiography during inspiratory and expiratory breath-holds. Centerline paths of the aorta and visceral arteries were acquired by geometric modeling and segmentation techniques. Vessel translations and changes in branching angle and curvature resulting from respiration were computed from centerline paths.ResultsWith expiration, the SMA, LRA, and RRA bifurcation points translated superiorly by 12.4 mm ± 9.5, 14.5 mm ± 8.8, and 12.7 mm ± 6.4 (P < .001), and posteriorly by 2.2 mm ± 2.7, 4.9 mm ± 4.2, and 5.6 mm ± 3.9 (P < .05), respectively, and the SMA translated rightward by 3.9 mm ± 4.9 (P < .01). With expiration, the SMA, LRA, and RRA angled upward by 9.7° ± 6.4, 7.5° ± 7.8, and 4.9° ± 5.3, respectively (P < .005). With expiration, mean curvature increased by 0.02 mm^?1 ± 0.01, 0.01 mm^?1 ± 0.01, and 0.01 mm^?1 ± 0.01 in the SMA, LRA, and RRA, respectively (P < .05). For inspiration and expiration, RRA curvature was greater than in other vessels (P < .025).ConclusionsWith expiration, the SMA, LRA, and RRA translated superiorly and posteriorly as a result of diaphragmatic motion, inducing upward angling of vessel branches and increased curvature. In addition, the SMA exhibited rightward translation with expiration. The RRA was significantly more tortuous, but deformed less than the other vessels during respiration.     

Uterine fibroids: Influence of “T2-Rim sign” on immediate therapeutic responses to magnetic resonance imaging-guided high-intensity focused ultrasound ablation

ObjectivesTo investigate the influence of a high-signal-intensity peripheral rim on T2-weighted MR images (i.e., T2-rim sign) on the immediate therapeutic responses of MR-guided high intensity focused ultrasound (MR-HIFU) ablation of uterine fibroids.MethodsThis retrospective study was approved by the institutional review board, and patient informed consent was obtained for MR-HIFU ablation. In total, 196 fibroids (diameter 6.2 ± 2.6 cm) in 123 women (age 43.4 ± 5.0 years) who underwent MR-HIFU ablation from January 2013 to April 2016 were included. The effects of a T2-rim sign on the immediate therapeutic responses (non-perfused volume [NPV] ratio, ablation efficiency [NPV/treatment cell volume], ablation quality [grade 1-5, poor to excellent]) were investigated with univariable and multivariable analyses using generalized estimating equation (GEE) analysis. In multivariable analysis, T2 signal intensity ratio of fibroids-to-skeletal muscle, relative peak enhancement of fibroids, and subcutaneous fat thickness were also considered.ResultsThe presence of a T2-rim sign significantly lowered the NPV ratio (54.0 ± 28.0% vs. 83.7 ± 17.7%), ablation efficiency (0.6 ± 0.5 vs. 1.3 ± 0.6), ablation quality (3.1 ± 1.2 vs. 4.2 ± 0.8), (P < 0.0001). GEE analysis showed that the presence of a T2-rim sign was independently significant for ablation efficiency and ablation quality (P < 0.05).ConclusionUterine fibroids with a T2-rim sign showed significantly poorer immediate therapeutic responses to MR-HIFU ablation.     

Raw-data-based iterative reconstruction versus filtered back projection: image quality of low-dose chest computed tomography examinations in 87 patients

ObjectiveThe objective was to compare standard-dose chest computed tomography (CT) reconstructed with filtered back projection (FBP) versus low-dose images with FBP and raw-data-based iterative reconstruction.MethodsEighty-seven consecutive patients (46 male; mean age, 54.54±16.12; mean body mass index, 24.58±4.07) referred for initial chest CT with full-dose examinations [mean dose–length product (DLP), 183.37±44.13 mGy·cm] and follow-up chest CT with half-dose examinations (mean DLP, 91.08±23.81 mGy·cm) were included. The full-dose protocol was reconstructed with FBP; the half-dose protocol was reconstructed with FBP and sinogram-affirmed iterative reconstruction (SAFIRE). Noise and signal-to-noise ratio were compared using a paired Student’s t test; subjective image quality and lesion conspicuity were compared using Wilcoxon signed ranks test.ResultsActual radiation dose of follow-up CT was about 50% (49.26%±2.62%) of standard-dose protocol. Compared to full-dose images with FBP, there was no significant difference in half-dose images with SAFIRE in the objective noise (ascending aorta: P= .38, descending aorta: P= .70, trachea on mediastinal images: P= .37) and SNR (ascending aorta: P= .14, descending aorta: P= .72, trachea on mediastinal images: P= .06) on mediastinal images. Noise was significantly lower (P< .001) and SNR was significantly higher (P< .001) in half-dose images with SAFIRE on lung images. Noise was significantly higher (P< .001) and SNR was significantly lower (P< .001) in half-dose images with FBP. Subjective image quality was similar on both mediastinal images (P= .317) and lung images (P= .614) of half-dose SAFIRE images versus full-dose FBP images. Lesion conspicuity was also similar. Subjective image quality was significantly lower on both mediastinal images (P< .001) and lung images (P< .001) of half-dose FBP images versus full-dose FBP images. The conspicuity of some lesions was significantly lower (ground-glass opacity, P< .0001; ill-defined micronodule, P< .0001; lung cyst, P< .0001; emphysematous lesion, P= .003) on half-dose FBP versus full-dose FBP images.ConclusionCompared to full-dose CT images reconstructed with the conventional FBP algorithm, SAFIRE with three iterations could provide similar or better image quality at 50% less dose.     

Normative values for three clinical measures of motor performance used in the neurological assessment of sports concussion

Postural control and motor coordination are essential components of normal athletic activity. Tasks involving balance and coordination are used to determine neurological function in sports-related concussion. Determining normative values for these tasks is therefore essential to provide sports medicine professionals with a frame of reference with which to interpret clinical measures obtained from players suspected of sustaining a concussion. One hundred and seventytwo healthy subjects (16–37 yrs) performed three timed tests: Tandem Gait (TG); Finger-to-Nose (FTN); Single-Leg-Stance (SLS) on firm and foam surfaces. Unadjusted geometric means (±SD) for each measure were averaged across three trials. Time to complete TG was 11.2 ± 1.2 s. FTN for the dominant and non-dominant arm were 2.9 ± 1.1 s and 3.0 ± 1.2 s, respectively. SLS values for dominant and non-dominant leg were 20.4 ± 3.0 s (firm), 3.4 ± 1.6 s (foam), and 21.0 ± 2.9 s (firm), 3.3 ± 1.6 s (foam), respectively. For TG, there was an order effect (P < .001) but no age, sex or BMI effects. FTN demonstrated a dominant arm preference (P < .001), sex (P = .006), BMI (P = .043) and order effects (P < .001). SLS demonstrated an order effect on the firm surface (P = .009) and an order (P < .001) and BMI (P = .001) effect on foam. Intra-rater reliability, as measured by ICC (3,3), demonstrated that TG and FTN had excellent reliability compared to SLS. FTN and TG should continue to be used in test batteries to determine neurological function in sports-related concussion.     

Comparación de la calidad de imagen y dosis de radiación en angio-tomografía computarizada de arterias periféricas con 80 y 100 kV

ObjectiveTo compare the image quality and dose of radiation in two groups of patients undergoing CT angiography of the lower limbs, one with tube voltage of 80 kV and the other with tube voltage of 100 kV.Material and methodsWe performed CT angiography of the lower limbs in 60 patients with suspected peripheral arterial disease. Patients were randomly assigned to one of two groups; in one group, CT angiography was performed using a tube voltage of 80 kV, whereas in the other it was performed using 100 kV. The remaining acquisition parameters were the same in both groups. The images were analyzed by quantifying vascular density (VD) and noise (N) and by calculating the quotients density/noise (QVDN) and contrast/noise (QCN). Two radiologists working independently evaluated the subjective quality of the images. We calculated the estimated effective dose (EED) based on the dose-length product (DLP).ResultsIn the group studied at 80 kV, VD was significantly higher (462.5 UH ± 95.6 vs. 372 UH ± 100.9; P <. 001), QVDN was significantly higher (241.9 ± 48.1 vs. 194.3 ± 49.6; P < .001), and there were trends toward higher N (21.3 UH ± 13 vs. 16.3 UH ± 3.5; P = .098) and toward higher QCN (21.4 ± 12.1 vs. 22.9 ± 9.1; P = .15). No significant differences were found in the subjective quality of the images. The EED was significantly lower in the group studied at 80 kV (4.73 mSv ± 1.1 vs. 9.6 mSv ± 2.2; P <. 001).ConclusionUsing 80 kV instead of 100 kV for CT angiography of the lower limbs reduces the dose of radiation without affecting the diagnostic efficacy of the study.     

Impact of Intrahepatic Venovenous Shunt on Hepatic Venous Pressure Gradient Measurement

PurposeTo quantitatively analyze the impact of intrahepatic venovenous shunt (IHVS) on hepatic venous pressure gradient (HVPG) measurement.Materials and MethodsFrom 2015 to 2019, 222 HVPG measurements performed during transjugular intrahepatic portosystemic shunt creation were eligible for this study. Digital subtraction angiography (DSA) software color-coded each pixel of a two-dimensional DSA series by time-intensity curve to classify IHVS. Different degrees of IHVS were found in 36.5% of patients (81/222). Mild IHVS was found in 10.8% of patients (24/222), moderate IHVS was found in 10.8% of patients (24/222), and severe IVHS was found in 14.9% of patients (33/222).ResultsMean wedged hepatic vein pressure (WHVP) and HVPG were significantly lower in patients with IHVS compared with patients without IHVS (WHVP: 17.78 mm Hg ± 7.00 vs 24.89 mm Hg ± 8.69, P = .001; HVPG: 11.93 mm Hg ± 5.76 vs 18.6 mm Hg ± 6.85, P < .001). Mild IHVS had little effect on WHVP and HVPG. Mean WHVP and HVPG were 11 mm Hg lower in patients with moderate IHVS (WHVP: 20.38 mm Hg ± 8.38 vs 31.5 mm Hg ± 9.39, P = .026; HVPG: 13.88 mm Hg ± 6.33 vs 25.00 mm Hg ± 9.81, P < .001) and 15 mm Hg lower in patients with severe IHVS (WHVP: 13.45 mm Hg ± 5.28 vs 28.64 mm Hg ± 6.38, P = .017; HVPG: 8.27 mm Hg ± 3.85 vs 23.45 mm Hg ± 6.95, P < .001) than mean portal vein pressure and portal vein gradient.ConclusionsFor patients with moderate or severe IHVS, HVPG might greatly underestimate the actual value of portal vein pressure, and the portal vein should be catheterized to measure portal pressure.     

Effects of active vs. passive recovery on repeated rugby-specific exercises

The aim of this study was to determine the effects of active vs. passive recovery on performance of a rugby-specific intermittent test in rugby union players. Seven male rugby players (20.6 ± 0.5 yrs; 181.9 ± 10.0 cm; 94.5 ± 12.8 kg) performed in random order, over two separate sessions, a specific repeated-sprint rugby test, the Narbonne test (6 × 4 consecutive actions: 1, scrummaging; 2, agility sprinting; 3, tackling; 4, straight sprinting) with 30 s of passive or active recovery (running at 50% of maximal aerobic speed). The Narbonne tests were completed before (pre-test) and after (post-test) a 30-min rugby match. During the Narbonne test, scrum forces, agility and sprint times, heart rate and rate of perceived exertion were measured. Scrum forces were lower in active (74.9 ± 13.4 kg) than in passive recovery (90.4 ± 20.9 kg), only during the post-test (p < 0.05). Fatigue index (%) (p < 0.05) and total sprint time (s) (p < 0.01) were significantly greater in active than in passive recovery, both during the pre-test (11.5 ± 5.7% vs. 6.7 ± 4.5% and 18.1 ± 1.3 s vs. 16.9 ± 0.9 s) and the post-test (7.3 ± 3.3% vs. 4.3 ± 1.5% and 18.3 ± 1.6 s vs. 16.9 ± 1.1 s). Consequently, the results indicated that passive recovery enabled better performance during the Narbonne test. However, it is obviously impractical to suggest that players should stand still during and following repeated-sprint bouts: the players have to move to ensure they have taken an optimal position.     

The effects of compression garments on recovery of muscle performance following high-intensity sprint and plyometric exercise

This study compared the effects of compression garments on recovery of evoked and voluntary performance following fatiguing exercise. Eleven participants performed 2 sessions separated by 7 days, with and without lower-body compression garments during and 24 h post-exercise. Participants performed a 10-min exercise protocol of a 20-m sprint and 10 plyometric bounds every minute. Before, following, 2 h and 24 h post-exercise, evoked twitch properties of the knee extensors, peak concentric knee extension and flexion force were assessed, with blood samples drawn to measure lactate [La^?], pH, creatine kinase (CK), aspartate transaminase (AST) and c-reactive protein (C-RP). Heart rate, exertion (RPE) and muscle soreness (MS) measures were obtained pre- and post-exercise. No differences (P = 0.50–0.80) and small effect sizes (d < 0.3) were present for 20-m sprint (3.59 ± 0.22 vs. 3.59 ± 0.18 s) or bounding performance (17.13 ± 1.4 vs. 17.21 ± 1.7 m) in garment and control conditions. The decline and recovery in concentric force were not different (P = 0.40) between conditions. Full recovery of voluntary performance was observed 2 h post-exercise, however, evoked twitch properties remained suppressed 2 h post-exercise in both conditions. No differences (P = 0.40–0.80, d < 0.3) were present between conditions for heart rate, RPE, [La^?], pH, CK or C-RP. However, 24 h post-exercise a smaller change (P = 0.08; d = 2.5) in AST (23.1 ± 3.1 vs. 26.0 ± 4.0) and reduced (P = 0.01; d = 1.1) MS (2.8 ± 1.2 vs. 4.5 ± 1.4) were present in the garments. In conclusion the effects of compression garments on voluntary performance and recovery were minimal; however, reduced levels of perceived MS were reported following recovery in the garments.     

Effect of 5-aminolevulinic acid photodynamic therapy on keratinocyte proliferation and apoptosis in condyloma acuminatum

BackgroundThe effect of 5-aminolevulinic acid photodynamic therapy on keratinocyte proliferation and apoptosis in condyloma acuminatum tissues was evaluated.MethodsAn immunohistochemical method and TdT-mediated dUTP nick end labeling were performed to detect the positive expression of the keratinocyte proliferation-related gene Ki-67 and apoptosis, respectively, in condyloma acuminatum tissues.ResultsOf 52 cases, 44 showed positive expression of Ki-67 in condyloma acuminatum keratinocytes before the treatment, with a positive expression rate of 84.62% (44/52), an expression strength of mostly ++ − +++, and a Ki-67 proliferation index of 80.26 ± 5.07%. After treatment, 22 cases showed positive expression of Ki-67 in condyloma acuminatum keratinocytes, with a positive expression rate of 42.31% (22/52), an expression strength of mostly − − ++, and a proliferation index of 42.67 ± 3.06%. The differences in the positive expression rate, expression strength, and proliferation index in the before- and after-treatment groups were statistically significant (χ² = 20.070, P < 0.001). For visible apoptotic cells in condyloma acuminatum keratinocytes before the 5-aminolevulinic acid photodynamic treatment, the expression strength was mostly + − ++, and the average apoptotic index was 13.94 ± 2.35%; after treatment, the expression strength was mostly ++ − +++, and the average apoptotic index was 73.88 ± 7.65%; the difference in the apoptotic index between the before and after treatment groups was statistically significant (P < 0.001).Conclusion5-Aminolevulinic acid photodynamic therapy can inhibit the proliferation and promote the apoptosis of keratinocytes, and represents an effective mechanism for treating condyloma acuminatum.     

Alteration of neuromuscular function in squash

The alteration in neuromuscular function of knee extensor muscles was characterised after a squash match in 10 trained players. Maximal voluntary contraction (MVC) and surface EMG activity of vastus lateralis (VL) and vastus medialis (VM) muscles were measured before and immediately after a 1-h squash match. M-wave and twitch contractile properties were analysed following single stimuli. MVC declined (280.5 ± 46.8 vs. 233.6 ± 35.4 N m, ?16%; P < 0.001) after the exercise and this was accompanied by an impairment of central activation, as attested by decline in voluntary activation (76.7 ± 10.4 vs. 71.3 ± 9.6%, ?7%; P < 0.05) and raw EMG activity of the two vastii (?17%; P < 0.05), whereas RMS/M decrease was lesser (VL: ?5%; NS and VM: ?12%; P = 0.10). In the fatigued state, no significant changes in M-wave amplitude (VL: ?9%; VM: ?5%) or duration were observed. Following exercise, the single twitch was characterised by lower peak torque (?20%; P < 0.001) as well as shorter half-relaxation time (?13%; P < 0.001) and reduced maximal rate of twitch tension development (?23%; P < 0.001) and relaxation (?17%; P < 0.05). A 1-h squash match play caused peripheral fatigue by impairing excitation–contraction coupling, whereas sarcolemmal excitability seems well preserved. Our results also emphasise the role of central activation failure as a possible mechanism contributing to the torque loss observed in knee extensors. Physical conditioners should consider these effects when defining their training programs for squash players.     

Spatial and temporal gait parameters in Alzheimer's disease and aging

Spatial and temporal gait parameters in 40 patients with early Alzheimer's disease (AD) were compared to that of 34 normal controls (NC) on a level ground and on a treadmill. Over-ground velocity, cycle-time, cadence, stride-length, stride-width and double-support time were captured on an electronic walkway. On the treadmill, cadence, cycle-time and double-support time were recorded at a preferred velocity using footswitches. The AD group were significantly slower on the Timed Up and Go task compared to NC (p < 0.05). AD patients differed significantly from the NC on their over-ground gait velocity (99 ± 19 cm/s vs 119 + 15 cm/s, p < 0.001), cadence (101 ± 9 steps/min vs 109 ± 9 steps/min, p = 0.001) and stride-length (118 ± 18 cm vs 131 ± 17 cm, p < 0.01). On the treadmill, only preferred speed was significantly different in the AD group compared to the NC group (60 ± 20 cm/s vs 74 ± 23 cm/s, p = 0.02). These results indicate that patients with early AD walk slower and with shorter strides than healthy older adults.     

High-intensity focused ultrasound combined with transarterial chemoembolization for unresectable hepatocellular carcinoma: Long-term follow-up and clinical analysis

ObjectiveHigh-intensity focused ultrasound (HIFU) combined with transarterial chemoembolization (TACE) has been used to treat unresectable HCC, but its long-term effects and major prognostic factors remain to be determined. The purpose of this study was to assess its long-term effects and find major prognostic factors to help us select eligible patients in the future.Methods73 patients with unresectable HCC received follow-up after HIFU + TACE. The variables of sex, age, AFP level, liver function, tumor location, tumor number, tumor size, TNM staging (5th edition), TNM staging (6th edition), portal vein invasion, ultrasonic pathway of HIFU, TACE session and ablation response were evaluated by univariate analysis. Those variables with significant difference were assessed by multivariate analysis.ResultsThe mean follow-up time was 11.7 ± 11.1 months (range, 1–60 months). The median survival time and overall survival rates of 1, 2, 3-year were 12 months, 49.1%, 18.8%, 8.4%, respectively. 45.2% patients achieved complete ablation. At the end of follow-up, 51 patients (69.9%) died from tumor progression (27 patients), liver function failure (18 patients), hemorrhage of upper digestive tract (3 patients) and infection (3 patients). 1 with liver abscess, 2 with serious skin burns and 2 with rib fracture were observed after HIFU. On univariate analysis, age (P = 0.017), tumor size (P = 0.000), tumor number (P = 0.039), the 5th edition of TNM staging (P = 0.023), portal vein invasion (P = 0.02) and ablation response (P = 0.000) had significant difference. On multivariate analysis, ablation response (P = 0.001) and tumor size (P = 0.013) were major prognostic factors.ConclusionHIFU combined with TACE is a safe method with a low rate of severe complications. As major prognostic factors, ablation response and tumor size may help us predict the survival and select eligible patients clinically.     

Heat stress impairs proprioception but not running mechanics

ObjectivesTo determine the effects of heat stress on ankle proprioception and running gait pattern.DesignCounterbalanced repeated measures.Methods12 trained runners performed a proprioception test (active movement discrimination) before and immediately after a 30 min, self-paced treadmill run in HOT (39 °C) and COOL (22 °C) ambient conditions. Velocity was imposed during the first and last minute (70% of maximal aerobic velocity, 13.3 ± 0.8 km h⁻¹) for determination of running mechanics and spring–mass characteristics.ResultsRectal (39.7 ± 0.4 vs. 39.4 ± 0.4 °C), skin (36.3 ± 1.1 vs. 31.8 ± 1.1 °C) and average body (38.3 ± 0.2 vs. 36.4 ± 0.4 °C) temperatures together with heart rate (178 ± 8 vs. 174 ± 6 bpm) and thermal discomfort (6.5 ± 0.5 vs. 4.3 ± 1.3) were all higher at the end of the HOT compared to COOL run (all p < 0.05). Distance covered was lower in HOT than COOL (−5.1 ± 3.6%, p < 0.001). Average error during the proprioception test increased after running in HOT (+11%, p < 0.05) but not in COOL (−2%). There was no significant difference for most segmental and joint angles at heel contact, except for a global increase in pelvis retroversion and decrease in ankle dorsi-flexion angles with time (p < 0.05). Step frequency decreased (−2.5 ± 3.6%) and step length increased (+2.6 ± 3.8%) over time (p < 0.05), independently of condition. Spring–mass characteristics remained unchanged (all p > 0.05).ConclusionsHeat stress exacerbates thermal, cardiovascular and perceptual responses, while running velocity was slower during a 30 min self-paced treadmill run. Heat stress also impairs ankle proprioception during an active movement discrimination task, but it has no influence on gait pattern assessed at a constant, sub-maximal velocity.     

Physiological factors determining downhill vs uphill running endurance performance

ObjectivesRecent studies investigated the determinants of trail running performance (i.e., combining uphill (UR) and downhill running sections (DR)), while the possible specific physiological factors specifically determining UR vs DR performances (i.e., isolating UR and DR) remain presently unknown. This study aims to determine the cardiorespiratory responses to outdoor DR vs UR time-trial and explore the determinants of DR and UR performance in highly trained runners.DesignRandomized controlled trial.MethodsTen male highly-trained endurance athletes completed 5-km DR and UR time-trials (average grade: ±8%) and were tested for maximal oxygen uptake, lower limb extensor maximal strength, local muscle endurance, leg musculotendinous stiffness, vertical jump ability, explosivity/agility and sprint velocity. Predictors of DR and UR performance were investigated using correlation and commonality regression analyses.ResultsRunning velocity was higher in DR vs UR time-trial (20.4 ± 1.0 vs 12.0 ± 0.5 km·h^?1, p < 0.05) with similar average heart rate (95 ± 2% vs 94 ± 2% maximal heart rate; p > 0.05) despite lower average V?O₂ (85 ± 8% vs 89 ± 7% V?O_2max; p < 0.05). Velocity at V?O_2max (vV?O_2max) body mass index (BMI) and maximal extensor strength were significant predictors of UR performance (r² = 0.94) whereas vV?O_2max, leg musculotendinous stiffness and maximal extensor strength were significant predictors of DR performance (r² = 0.84).ConclusionsFive-km UR and DR running performances are both well explained by three independent predictors. If two predictors are shared between UR and DR performances (vV?O_2max and maximal strength), their relative contribution is different and, importantly, the third predictor appears very specific to the exercise modality (BMI for UR vs leg musculotendinous stiffness for DR).     

Difference in the craniocaudal gradient of the maximum pixel value change rate between chronic obstructive pulmonary disease patients and normal subjects using sub-mGy dynamic chest radiography with a flat panel detector system

ObjectivesTo compare the craniocaudal gradients of the maximum pixel value change rate (MPCR) during tidal breathing between chronic obstructive pulmonary disease (COPD) patients and normal subjects using dynamic chest radiography.Materials and methodsThis prospective study was approved by the institutional review board and all participants provided written informed consent. Forty-three COPD patients (mean age, 71.6 ± 8.7 years) and 47 normal subjects (non-smoker healthy volunteers) (mean age, 54.8 ± 9.8 years) underwent sequential chest radiographs during tidal breathing in a standing position using dynamic chest radiography with a flat panel detector system. We evaluated the craniocaudal gradient of MPCR. The results were analyzed using an unpaired t-test and the Tukey–Kramer method.ResultsThe craniocaudal gradients of MPCR in COPD patients were significantly lower than those in normal subjects (right inspiratory phase, 75.5 ± 48.1 vs. 108.9 ± 42.0 s⁻¹ cm⁻¹, P < 0.001; right expiratory phase, 66.4 ± 40.6 vs. 89.8 ± 31.6 s⁻¹ cm⁻¹, P = 0.003; left inspiratory phase, 75.5 ± 48.2 vs. 108.2 ± 47.2 s⁻¹ cm⁻¹, P = 0.002; left expiratory phase, 60.9 ± 38.2 vs. 84.3 ± 29.5 s⁻¹ cm⁻¹, P = 0.002). No significant differences in height, weight, or BMI were observed between COPD and normal groups. In the sub-analysis, the gradients in severe COPD patients (global initiative for chronic obstructive lung disease [GOLD] 3 or 4, n = 26) were significantly lower than those in mild COPD patients (GOLD 1 or 2, n = 17) for both right and left inspiratory/expiratory phases (all P ≤ 0.005).ConclusionsA decrease of the craniocaudal gradient of MPCR was observed in COPD patients. The craniocaudal gradient was lower in severe COPD patients than in mild COPD patients.     

The influence of passive heat maintenance on lower body power output and repeated sprint performance in professional rugby league players

Objectives: The pre-competition warm-up mediates many temperature related physiological changes which generally lead to an improvement in performance. However, after ceasing exercise body temperature declines rapidly, which reduces some of the benefits of the initial warm-up. We examined the effects of a passive heat maintenance strategy on post-warm-up core temperature (T_core) and performance in professional rugby league players. Design: Twenty professional rugby league players completed this randomised and counter-balanced study. Methods: After a standardised warm-up, players completed a countermovement jump (CMJ) before resting for 15 min wearing normal training attire (control) or wearing a passive heat maintenance jacket (PHM), players then completed another CMJ and a repeated sprint protocol (RSA). T_core was measured at baseline, post-warm-up, pre-RSA and post-RSA. CMJ were analysed for peak power output (PPO), and RSA for fastest, mean and total sprint time. Results: Post-warm-up T_core (mean ± SD; control 37.70 ± 0.28; PHM 37.70 ± 0.27 °C; p = 0.741) and PPO (control 5220 ± 353 vs. PHM 5213 ± 331 W; p = 0.686) were similar between conditions. At pre-RSA, PHM was associated with greater T_core (control 37.14 ± 0.31 vs. PHM 37.51 ± 0.30 °C; p < 0.001) and PPO (control 4868 ± 345 vs. PHM 5056 ± 344 W; p < 0.001) when compared to control. The decline in PPO from post-warm-up to pre-RSA was related to the drop in T_core (r = 0.71; p < 0.001). During the RSA, fastest, mean and total sprint time were all improved under PHM compared to control (p < 0.05). Conclusions: Passive heat maintenance is an effective method of attenuating the post-warm-up decline in T_core and improves PPO and repeated sprint ability in professional rugby league players.