Toxicology evaluation of radiotracer doses of 3'-deoxy-3'-[18F]fluorothymidine (18F-FLT) for human PET imaging: Laboratory analysis of serial blood samples and comparison to previously investigated therapeutic FLT doses

Background

Transient arrhythmias can affect transient ischemic dilation (TID) ratios. This study was initiated to evaluate the frequency and effect of normal heart rate change on TID measures in routine clinical practice.

Methods

Consecutive patients undergoing stress/rest sestamibi gated myocardial perfusion scintigraphy were studied (N = 407). Heart rate at the time of stress and rest imaging were recorded. TID ratios were analyzed in relation to absolute change in heart rate (stress minus rest) for subjects with normal perfusion and systolic function (Group 1, N = 169) and those with abnormalities in perfusion and/or function (Group 2, N = 238).

Results

In Group 1, mean TID ratio was inversely correlated with the change in heart rate (r = -0.47, P < 0.0001). For every increase of 10 BPM in heart rate change, the TID ratio decreased by approximately 0.06 (95% confidence interval 0.04–0.07). In Group 2, multiple linear regression demonstrated that the change in heart rate (beta = -0.25, P < 0.0001) and the summed difference score (beta = 0.36, P < 0.0001) were independent predictors of the TID ratio.

Conclusion

Normal variation in heart rate between the stress and rest components of myocardial perfusion scans is common and can influence TID ratios in patients with normal and abnormal cardiac scans.     

Retrospective Analysis of TREC Based Newborn Screening Results and Clinical Phenotypes in Infants with the 22q11 Deletion Syndrome

Purpose

Population-based newborn screening using T-cell receptor excision circles (TREC) identifies infants with severe T-lymphopenia, seen in severe combined immunodeficiencies (SCID), but also infants with the 22q11 deletion syndrome (22q11DS). Methods for analysis of kappa-deleting recombination excision circles (KREC) help identifying infants with B-lymphopenia. We aimed to evaluate the occurrence of abnormal TREC or KREC newborn screening results in 22q11DS patients and assessed the clinical relevance of abnormal screening reports.

Methods

Simultaneous TREC and KREC analysis was performed on stored original Guthrie cards. Patients with abnormal screening reports were compared to patients with normal reports, regarding lymphocyte counts and clinical severity, obtained by retrospective analysis of medical charts.

Results

Of 48 included patients, nine (19 %) had abnormal TREC copy numbers. All 22q11DS patients with abnormal TRECs had CD3+ T-lymphopenia at the time of diagnosis, but only one patient had the complete DiGeorge syndrome. Identified 22q11DS patients with abnormal TREC copy numbers showed significantly lower CD8+ T-lymphocytes at time-of-diagnosis and were significantly more prone to viral infections, compared to 22q11DS patients with normal TREC copy numbers. All 22q11DS patients showed KREC copies within the normal range.

Conclusions

In this retrospective study a high proportion of 22q11DS patients were identified by TREC-based newborn screening. Although only one of them had the complete DiGeorge syndrome with no T-lymphocytes, all of them had T-lymphopenia and most of them had recurrent viral infections, as well as other medical problems, warranting early recognition of the syndrome.     

Breast cancer detection using sonography in women with mammographically dense breasts

Background

The European Society of Cardiology recommends that patients with >10% area of ischemia should receive revascularization. We investigated inter-observer variability for the extent of ischemic defects reported by different physicians and by different software tools, and if inter-observer variability was reduced when the physicians were provided with a computerized suggestion of the defects.

Methods

Twenty-five myocardial perfusion single photon emission computed tomography (SPECT) patients who were regarded as ischemic according to the final report were included. Eleven physicians in nuclear medicine delineated the extent of the ischemic defects. After at least two weeks, they delineated the defects again, and were this time provided a suggestion of the defect delineation by EXINI Heart^TM (EXINI). Summed difference scores and ischemic extent values were obtained from four software programs.

Results

The median extent values obtained from the 11 physicians varied between 8% and 34%, and between 9% and 16% for the software programs. For all 25 patients, mean extent obtained from EXINI was 17.0% (± standard deviation (SD) 14.6%). Mean extent for physicians was 22.6% (± 15.6%) for the first delineation and 19.1% (± 14.9%) for the evaluation where they were provided computerized suggestion. Intra-class correlation (ICC) increased from 0.56 (95% confidence interval (CI) 0.41-0.72) to 0.81 (95% CI 0.71-0.90) between the first and the second delineation, and SD between physicians were 7.8 (first) and 5.9 (second delineation).

Conclusions

There was large variability in the estimated ischemic defect size obtained both from different physicians and from different software packages. When the physicians were provided with a suggested delineation, the inter-observer variability decreased significantly.     

CAG正常伴心绞痛症状患者行核素心肌灌注显像的临床意义

目的:探讨核素心肌显像在冠状动脉造影(CAG)正常伴心绞痛症状患者中的临床意义。方法:应用99Tcm-MIBI负荷/静息门控心肌灌注断层显像(MPT)分析上述患者显像特点。A组(心血管神经症)15例,B组(原发性高血压)24例,C组(X综合征)20例,D组(Ⅱ型糖尿病)18例。结果:A组有2例3个节段可逆性缺损,评分均为1;B、C、D组均有多节段可逆性或部分可逆性缺损,异常机率明显高于A组(P<0.001),评分为1.12±0.28、1.08±0.36、1.42±0.56,B、C组无明显差异(P>0.05),D组与B或C组有差异(P<0.01)。比较静息LVEF,A组与B、C组无明显差异(P>0.05),D组略低于A组(P<0.01)。结论:MPT可反映CAG正常伴心绞痛患者心肌血流的分布状况,显示病变的范围及程度。     

Thallium scintigraphy in prediction of occlusion of bypass grafts in asymptomatic and symptomatic patients

To evaluate thallium scintigraphy in predicting coronary artery bypass graft patency, exercise thallium scintigraphy and selective graft and native vessel angiograms were performed in 22 asymptomatic and 29 symptomatic consecutive patients three months after coronary artery bypass grafting (CABG). Twelve out of 22 asymptomatic patients (55%) had reversible thallium defects on postoperative images; in 10 patients the postoperative scans were normal. The graft patency was significantly lower in asymptomatic patients with abnormal thallium perfusion compared to those with normal perfusion after CABG (68% vs. 91%, p less than 0.05). The rate of graft patency in symptomatic patients was 66/87 (76%). Thallium scintigraphy was 77% sensitive and 78% specific in detecting one or more stenosed or occluded bypass grafts in patients without angina (accuracy 77%). When data from exercise electrocardiography were combined with scintigraphy, all but one patient with incomplete revascularization could be detected (positive predictive accuracy 92%). In symptomatic patients, thallium scintigraphy accurately predicted the presence or absence of graft occlusion in 24/29 (83%) cases. Thus, abnormal myocardial perfusion due to stenosis or occlusion of bypass grafts is common in both asymptomatic and symptomatic patients after CABG. Thallium scintigraphy together with exercise electrocardiography appear to be useful non-invasive methods in detecting painless myocardial ischemia and in predicting bypass graft occlusion after CABG.     

A statistical investigation of normal regional intra-subject heterogeneity of brain metabolism and perfusion by F-18 FDG and O-15 H2O PET imaging

Background

The definite evaluation of the regional cerebral heterogeneity using perfusion and metabolism by a single modality of PET imaging has not been well addressed. Thus a statistical analysis of voxel variables from identical brain regions on metabolic and perfusion PET images was carried out to determine characteristics of the regional heterogeneity of F-18 FDG and O-15 H₂O cerebral uptake in normal subjects.

Methods

Fourteen normal subjects with normal CT and/or MRI and physical examination including MMSE were scanned by both F-18 FDG and O-15 H₂O PET within same day with head-holder and facemask. The images were co-registered and each individual voxel counts (Q) were normalized by the gloabl maximal voxel counts (M) as R = Q/M. The voxel counts were also converted to z-score map by z = (Q - mean)/SD. Twelve pairs of ROIs (24 total) were systematically placed on the z-score map at cortical locations 15-degree apart and identically for metabolism and perfusion. Inter- and intra-subject correlation coefficients (r) were computed, both globally and hemispherically, from metabolism and perfusion: between regions for the same tracer and between tracers for the same region. Moments of means and histograms were computed globally along with asymmetric indices as their hemispherical differences.

Results

Statistical investigations verified with data showed that, for a given scan, correlation analyses are expectedly alike regardless of variables (Q, R, z) used. The varieties of correlation (r's) of normal subjects, showing symmetry, were mostly around 0.8 and with coefficient of variations near 10%. Analyses of histograms showed non-Gaussian behavior (skew = -0.3 and kurtosis = 0.4) of metabolism on average, in contrast to near Gaussian perfusion.

Conclusion

The co-registered cerebral metabolism and perfusion z maps demonstrated regional heterogeneity but with attractively low coefficient of variations in the correlation markers.     

Abnormal ECG Patterns in Chronic Post-War PTSD Patients: A Pilot Study

Background

Posttraumatic stress disorder (PTSD) is a psychiatric syndrome associated with high levels of sympathetic activation of the autonomic nervous system. Individuals diagnosed with PTSD have a high propensity for electrocardiogram (ECG) abnormalities, atrioventricular conductive defects, and cerebrovascular incidents.

Purpose

The aim of this study was to investigate ECG abnormalities in post-war PTSD patients.

Method

This pilot study compared patients diagnosed with chronic post-war PTSD (n?=?30) to patients diagnosed with major depressive disorder (MDD; n?=?24) and healthy controls (n?=?20). Following the completion of the Structured Clinical Interview for the DSM (SCID), participants were assessed with a standard 12-lead ECG.

Results

ECG abnormalities were observed in 66.7% of PTSD patients and 70.8% of MDD patients. In contrast, only 28.6% of the healthy control group showed ECG abnormalities. Multivariate logistic regression was used to adjust for participants' sex, smoking rate, education level, disease duration, and marital status. The results indicated that PTSD and MDD patients were more likely to have ECG abnormalities than the normal population (odds ratio for PTSD?=?12.7, 95% confidence interval 1.9–83.9; and odds ratio for MDD?=?14.9, 95% confidence interval 1.3–170.5).

Conclusion

PTSD and MDD patients showed elevated rates of ECG abnormalities compared to healthy controls. These findings have important implications for the medical treatment of PTSD and MDD given that both of these patient groups appear to be at increased risk of cardiovascular disorder.     

Cardiovascular Risk: Gender Differences in Lifestyle Behaviors and Coping Strategies

Background

Although cardiovascular disease (CVD) does not occur until mid to late life for most adults, the presence of risk factors, such as high blood pressure (BP) and cholesterol, has increased dramatically in young adults.

Purpose

The present study examined the relationships between gender and coping strategies, lifestyle behaviors, and cardiovascular risks.

Method

The sample consisted of 297 (71% female) university students. Participants completed a survey to assess demographics, lifestyle behaviors, and coping strategies, and a physiological assessment including lipid and blood pressure (BP) measurements. Data collection occurred from January 2007 to May 2008.

Results

Analyses revealed that age, ethnicity, greater body mass index (BMI), greater use of social support, and less frequent exercise were associated with higher cholesterol, while gender, age, greater BMI, and less frequent exercise were associated with higher systolic BP. There were two significant interactions: one between gender and avoidant coping and the other between gender and exercise on systolic BP, such that for men greater use of avoidant coping or exercise was associated with lower systolic BP.

Conclusion

Understanding how young adults manage their demands and cope with stress sets the stage for understanding the developmental process of CVD. Both coping strategies and lifestyle behaviors must be considered in appraising gender-related cardiovascular risk at an early age before the disease process has begun.     

Elevated white cell count in acute coronary syndromes: relationship to variants in inflammatory and thrombotic genes

Background

Elevated white blood cell counts (WBC) in acute coronary syndromes (ACS) increase the risk of recurrent events, but it is not known if this is exacerbated by pro-inflammatory factors. We sought to identify whether pro-inflammatory genetic variants contributed to alterations in WBC and C-reactive protein (CRP) in an ACS population.

Methods

WBC and genotype of interleukin 6 (IL-6 G-174C) and of interleukin-1 receptor antagonist (IL1RN intronic repeat polymorphism) were investigated in 732 Caucasian patients with ACS in the OPUS-TIMI-16 trial. Samples for measurement of WBC and inflammatory factors were taken at baseline, i.e. Within 72 hours of an acute myocardial infarction or an unstable angina event.

Results

An increased white blood cell count (WBC) was associated with an increased C-reactive protein (r = 0.23, p < 0.001) and there was also a positive correlation between levels of β-fibrinogen and C-reactive protein (r = 0.42, p < 0.0001). IL1RN and IL6 genotypes had no significant impact upon WBC. The difference in median WBC between the two homozygote IL6 genotypes was 0.21/mm³ (95% CI = -0.41, 0.77), and -0.03/mm³ (95% CI = -0.55, 0.86) for IL1RN. Moreover, the composite endpoint was not significantly affected by an interaction between WBC and the IL1 (p = 0.61) or IL6 (p = 0.48) genotype.

Conclusions

Cytokine pro-inflammatory genetic variants do not influence the increased inflammatory profile of ACS patients.     

Inflammatory Bowel Disease and T cell Lymphopenia in G6PC3 Deficiency

Purpose

G6PC3 deficiency presents as a complex and heterogeneous syndrome that classically associates severe congenital neutropenia with cardiac and urogenital developmental defects. Here we investigate the findings of T cell lymphopenia and inflammatory bowel disease in a child with G6PC3 deficiency due to compound heterozygous mutations in intron 3 (c.IVS3-1 G>A) and exon 6 (c.G778G/C; p.Gly260/Arg).

Methods

Histological examination was conducted on all biopsy specimens. Immunophenotyping and lymphocyte proliferation assays were performed. Immunoglobulin levels and vaccine responses were measured.

Results

The patient showed persistent global T cell lymphopenia, with only 8 to 13 % of thymic naive CD31⁺CD45RA⁺ cells among CD4 T cells (normal range 27–60 %). Proliferation assays and vaccine responses were within normal limits. The gastrointestinal inflammatory lesions were very closely related to those of glycogen storage disease type 1b, with a Crohn’s-like appearance but without granuloma or increased cryptic abscesses. The gastrointestinal disease responded to infliximab therapy. These findings were associated with a polyclonal hypergammaglobuliemia G.

Conclusion

G6PC3 deficiency may present with inflammatory bowel disease and T cell lymphopenia. The diagnosis should thus be considered in a patient with chronic congenital neutropenia and gastrointestinal symptoms. Patients with confirmed disease should also undergo T cell phenotyping to rule out cellular immunodeficiency.     

Predicting Automaticity in Exercise Behaviour: The Role of Perceived Behavioural Control,Affect, Intention,Action Planning,and Behaviour

Background

Habit formation has been proposed as a way to maintain behaviour over time.

Purpose

Recent evidence suggests that constructs additional to repeated performance may predict physical automaticity, but no research has yet explored possible direct impacts of intention, planning, affect, and perceived behavioural control (PBC) on automaticity.

Method

In a prospective study over a 2-week period amongst 406 undergraduate students (M _age?=?21.5 years [SD?=?2.59], 27.4 % males), we investigated main and interaction effects of past exercise behaviour, PBC, intention, planning, and affect on exercise automaticity.

Results

Results showed that — controlling for past behaviour — PBC, affect, and planning were significant and positive predictors of exercise automaticity. Decomposing a significant interaction between PBC and planning when to exercise revealed that planning became less predictive of exercise automaticity at higher levels of PBC.

Conclusion

Findings show that exercise automaticity is predicted by repeated performance and social–cognitive constructs. Further, interactions between social–cognitive predictors may be different for behavioural automaticity than for behavioural frequency.     

Safety and efficacy of Y-90 microsphere treatment in patients with primary and metastatic liver cancer: The tumor selectivity of the treatment as a function of tumor to liver flow ratio

Background

Treatment records and follow-up data on 40 patients with primary and metastatic liver malignancies who underwent a single whole-liver treatment with Y-90 resin microspheres (SIR-Spheres^® Sirtex Medical, Lake Forest, IL) were retrospectively reviewed. The objective of the study was to evaluate the anatomic and physiologic determinants of radiation dose distribution, and the dose response of tumor and liver toxicity in patients with liver malignancies who underwent hepatic arterial Y-90 resin microsphere treatment.

Methods

Liver and tumor volume calculations were performed on pre-treatment CT scans. Fractional tumor and liver flow characteristics and lung shunt fractions were determined using hepatic arterial Tc-99m MAA imaging. Absorbed dose calculations were performed using the MIRD equations. Liver toxicity was assessed clinically and by liver function tests. Tumor response to therapy was assessed by CT and/or tumor markers.

Results

Of the 40 patients, 5 had hepatocellular cancer (HCC), and 35 had metastatic liver tumors (15 colorectal cancer, 10 neuroendocrine tumors, 4 breast cancer, 2 lung cancer, 1 ovarian cancer, 1 endometrial cancer, and 2 unknown primary adenocarcinoma). All patients were treated in a salvage setting with a 3 to 80 week follow-up (mean: 19 weeks). Tumor volumes ranged from 15.0 to 984.2 cc (mean: 294.9 cc) and tumor to normal liver uptake ratios ranged from 2.8 to 15.4 (mean: 5.4). Average administered activity was 1.2 GBq (0.4 to 2.4 GBq). Liver absorbed doses ranged from 0.7 to 99.5 Gy (mean: 17.2 Gy). Tumor absorbed doses ranged from 40.1 to 494.8 Gy (mean: 121.5 Gy). None of the patients had clinical venoocclusive disease or therapy-induced liver failure. Seven patients (17.5 %) had transient and 7 patients (17.5 %) had persistent LFT abnormalities. There were 27 (67.5%) responders (complete response, partial response, and stable disease). Tumor response correlated with higher tumor flow ratio as measured by Tc-99m MAA imaging.

Conclusion

Dosesup to99.5 Gy to uninvolved liver are tolerated with no clinical venoocclusive disease or liver failure.The lowest tumor dose producing a detectable response is 40.1 Gy.The utilization of MAA-based imaging techniques to determine tumor and liver blood flow for clinical treatment planning and the calculation of administered activity may improve clinical outcomes.     

Metabolic and cardiovascular responses during voluntary pedaling exercise with electrical muscle stimulation

Purpose

We aimed to test the effect of additional electrical muscle stimulation (EMS) during moderate-intensity voluntary pedaling exercise on metabolic and cardiovascular responses.

Methods

Eleven healthy male subjects performed moderate-intensity pedaling exercise at a constant workload (80 % of ventilatory threshold) for 20 min while EMS was applied to thigh muscles from 5 to 10 min and from 15 to 20 min during the exercise.

Results

A significantly higher oxygen uptake (VO₂), heart rate, and respiratory gas exchange ratio were observed during the exercise periods with EMS despite the constant workload. These changes were accompanied by an elevated blood lactate concentration, suggesting the existence of additional fast-twitch motor unit (MU) recruitment during the exercise with EMS.

Conclusion

Our data suggest that the use of intermittent EMS during a constant load exercise mimics the high-intensity interval training, possibly due to additional fast-twitch MU recruitment and co-contractions of the quadriceps and hamstrings muscles, leading to higher anaerobic metabolism and a lower mechanical efficiency.     

Influence of Self-Efficacy on Compliance to Workplace Exercise

Background

Continuous neck and shoulder pain is a common musculoskeletal complaint. Physical exercise can reduce pain symptoms, but compliance to exercise is a challenge. Exercise-specific self-efficacy has been found to be a predictor of participation in preplanned exercise. Little is known about the influence of exercise-specific self-efficacy on compliance to workplace physical exercise.

Purpose

To determine the influence of exercise-specific self-efficacy on compliance to specific strength exercises during working hours for laboratory technicians.

Methods

We performed a cluster-randomized controlled trial, including laboratory technicians from two industrial production units in Copenhagen, Denmark. The participants were randomized to supervised specific strength exercises for the neck and shoulder muscles for 20 minutes three times a week (n?=?282) or to a reference group (n?=?255). The participants answered baseline and follow-up questions regarding self-efficacy and registered all exercises in a diary.

Results

Overall compliance to exercises was 45 %. Compliance in company A (private sector) differed significantly between the three self-efficacy groups after 20 weeks. The odds ratio of compliance was 2.37 for moderate versus low self-efficacy, and 2.93 for high versus low self-efficacy. No significant difference was found in company B (public sector) or in the intervention group as a whole.

Conclusion

We did not find self-efficacy to be a general statistically significant predictor of compliance to exercises during 20 weeks, but found self-efficacy to be a predictor of compliance in a private sector setting. Workplace-specific differences might be present and should be taken into account.     

Influence of exercise intensity on respiratory muscle fatigue and brachial artery blood flow during cycling exercise

Purpose

During high intensity exercise, both respiratory muscle fatigue and cardiovascular reflexes occur; however, it is not known how inactive limb blood flow is influenced. The purpose of this study was to determine the influence of moderate and high exercise intensity on respiratory muscle fatigue and inactive limb muscle and cutaneous blood flow during exercise.

Methods

Twelve men cycled at 70 and 85 % \(\dot{V}{\text{O}}_{{ 2_{ {\rm max} } }}\) for 20 min. Subjects also performed a second 85 % \(\dot{V}{\text{O}}_{{ 2_{ {\rm max} } }}\) test after ingesting 1,800 mg of N-acetylcysteine (NAC), which has been shown to reduce respiratory muscle fatigue (RMF). Maximum inspiratory pressures (P _Imax), brachial artery blood flow (BABF), cutaneous vascular conductance (CVC), and mean arterial pressure were measured at rest and during exercise.

Results

Significant RMF occurred with 85 % \(\dot{V}{\text{O}}_{{ 2_{ {\rm max} } }}\) (P _Imax, ?12.8 ± 9.8 %), but not with 70 % \(\dot{V}{\text{O}}_{{ 2_{ {\rm max} } }}\) (P _Imax, ?5.0 ± 5.9 %). BABF and BA vascular conductance were significantly lower at end exercise of the 85 % \(\dot{V}{\text{O}}_{{ 2_{ {\rm max} } }}\) test compared to the 70 % \(\dot{V}{\text{O}}_{{ 2_{ {\rm max} } }}\) test. CVC during exercise was not different (p > 0.05) between trials. With NAC, RMF was reduced (p < 0.05) and BABF was significantly higher (~30 %) compared to 85 % \(\dot{V}{\text{O}}_{{ 2_{ {\rm max} } }}\) (p < 0.05).

Conclusions

These data suggest that heavy whole-body exercise at 85 % \(\dot{V}{\text{O}}_{{ 2_{ {\rm max} } }}\) leads to RMF, decreases in inactive arm blood flow, and vascular conductance, but not cutaneous blood flow.     

The effect of muscle fatigue on stimulus intensity requirements for central and peripheral fatigue quantification

Purpose

The present study was designed to determine the stimulation intensity necessary for an adequate assessment of central and peripheral components of neuromuscular fatigue of the knee extensors.

Methods

Three different stimulation intensities (100, 120 and 150 % of the lowest intensity evoking a plateau in M-waves and twitch amplitudes, optimal stimulation intensity, OSI) were used to assess voluntary activation level (VAL) as well as M-wave, twitch and doublet amplitudes before, during and after an incremental isometric exercise performed by 14 (8 men) healthy and physically active volunteers. A visual analog scale was used to evaluate the associated discomfort.

Results

There was no difference (p > 0.05) in VAL between the three intensities before and after exercise. However, we found that stimulating at 100 % OSI may overestimate the extent of peripheral fatigue during exercise, whereas 150 % OSI stimulations led to greater discomfort associated with doublet stimulations as well as to an increased antagonist co-activation compared to 100 % OSI.

Conclusion

We recommend using 120 % OSI, as it constitutes a good trade-off between discomfort and reliable measurements.     

Central and peripheral adjustments during high-intensity exercise following cold water immersion

Purpose

We investigated the acute effects of cold water immersion (CWI) or passive recovery (PAS) on physiological responses during high-intensity interval training (HIIT).

Methods

In a crossover design, 14 cyclists completed 2 HIIT sessions (HIIT1 and HIIT2) separated by 30 min. Between HIIT sessions, they stood in cold water (10 °C) up to their umbilicus, or at room temperature (27 °C) for 5 min. The natural logarithm of square-root of mean squared differences of successive R–R intervals (ln rMSSD) was assessed pre- and post-HIIT1 and HIIT2. Stroke volume (SV), cardiac output ( $ \dot{Q} $ ), O₂ uptake ( $ \dot{V} $ O₂), total muscle hemoglobin (t _Hb) and oxygenation of the vastus lateralis were recorded (using near infrared spectroscopy); heart rate, $ \dot{Q} $ , and $ \dot{V} $ O₂ on-kinetics (i.e., mean response time, MRT), muscle de-oxygenation rate, and anaerobic contribution to exercise were calculated for HIIT1 and HIIT2.

Results

ln rMSSD was likely higher [between-trial difference (90 % confidence interval) [+13.2 % (3.3; 24.0)] after CWI compared with PAS. CWI also likely increased SV [+5.9 % (?0.1; 12.1)], possibly increased $ \dot{Q} $ [+4.4 % (?1.0; 10.3)], possibly slowed $ \dot{Q} $ MRT [+18.3 % (?4.1; 46.0)], very likely slowed $ \dot{V} $ O₂ MRT [+16.5 % (5.8; 28.4)], and likely increased the anaerobic contribution to exercise [+9.7 % (?1.7; 22.5)].

Conclusion

CWI between HIIT slowed $ \dot{V} $ O₂ on-kinetics, leading to increased anaerobic contribution during HIIT2. This detrimental effect of CWI was likely related to peripheral adjustments, because the slowing of $ \dot{V} $ O₂ on-kinetics was twofold greater than that of central delivery of O₂ (i.e., $ \dot{Q} $ ). CWI has detrimental effects on high-intensity aerobic exercise performance that persist for ≥45 min.     

The Effect of a Multifaceted Efficacy Intervention on Exercise Behavior in Relatives of Colon Cancer Patients

Background

Regular physical activity (PA) provides health benefits; however, at least 60% of the population fails to engage in the recommended amount of PA required to produce these health benefits.

Purpose

The primary purpose of the study was to examine over a 12-week structured exercise program the effect of a multifaceted efficacy intervention (MEI??i.e., task and specific types of self-regulatory efficacy) on objectively measured exercise behavior. Secondary purposes were to examine the effect of the MEI on both task and self-regulatory efficacy levels; and to determine whether efficacy beliefs could predict exercise behavior.

Methods

Relatives of colon cancer patients (N?=?140) were enrolled in an exercise program, and were randomized to either a MEI or attention control condition, and took part in classroom sessions. Behavior was assessed throughout the 12-week program using objective measures of frequency, duration, and intensity of exercise, and dropout rates, while self-reported task, barrier, scheduling, goal-setting, and relapse prevention efficacy were assessed at baseline and weeks?4, 8, and 12.

Results

The MEI group exercised for longer duration in the early phase of the program (i.e., 0?C4?weeks); however, no significant differences were noted for exercise frequency and intensity. Differential dropout was found favoring the MEI group at weeks?8 and 12. No treatment condition differences were found for reported efficacy beliefs. Proceeding self-efficacious beliefs were associated with objective measures of behavior.

Conclusions

A MEI grounded in Social Cognitive Theory was partially effective in influencing colon cancer relatives?? exercise behavior.