Augmented Rehabilitation Program for Patients 60 Years and Younger Following Total Hip Arthroplasty-Feasibility Study.

The purpose of this study is to examine the feasibility, safety and outcomes of a study comparing a 6-week post-operative rehabilitation program to usual care in patients ≤60 years undergoing elective unilateral total hip arthroplasty (THA). Methods: A cohort of 24 THA patients were recruited during their 6-week postoperative visit to their surgeons. The community-based rehabilitation program, which was designed to improve function and increase activity, consisted of 12 structured exercise classes on land and water over 6 weeks. Physical activity was assessed using a Sense Wear Pro Armband (SWA). Participants completed the Hip Osteoarthritis Outcome Score (HOOS) and THA satisfaction questionnaire before and immediately after the intervention. Results: 14 participants received the augmented rehabilitation, and 10 participants were in the control group. All except one in the intervention group completed at least 80% of the sessions. The intervention group took significantly more steps/day (mean difference = 2440 steps/day, 95% CI = 1678, 4712) (p < 0.05), at the follow-up compared to baseline. The intervention group had a higher mean change of number of weekly PA bouts than the control group. Within the intervention group, all HOOS subscales were significantly higher at the follow-up compared to baseline. Conclusion: Findings provided pragmatic insight regarding the intervention and assessments of implementing an augmented rehabilitation program for elective THA.

Sedentary behavior and physical activity in cardiac rehabilitation participants.

BACKGROUND: There is a deleterious association between sedentary behavior and mortality risk factors. Elevated sedentary time has been reported in several studies that involved cardiac rehabilitation (CR) participants. OBJECTIVES: To examine the changes in sedentary behavior, breaks in sedentary time, and physical activity (PA) in CR participants. METHODS: This was a prospective repeated measures study. Sedentary behavior and PA were assessed using accelerometer at baseline, 12 weeks, and 6 months after CR entry. RESULTS: At 12 weeks, participants (n = 58) spent more time in moderate-vigorous PA (MVPA) and tended to be less sedentary. However, the changes were lost by 6 month follow-up. Although the majority of participants met the recommended MVPA, our participants demonstrated elevated sedentary time. We found a strong positive correlation between time in light PA and number of breaks in sedentary time; neither of which showed any changes over time. CONCLUSIONS: By promoting MVPA as their main target, current CR programs may have little impact on changing the elevated sedentary behavior of their participants. Further, interrupting sedentary time with light PA could be an achievable strategy to reduce sedentary behavior in CR participants.

Impact of Cardiac Resynchronization Therapy on Daily Physical Activity in Heart Failure Patients.

PURPOSE: Cardiac resynchronization therapy (CRT) has emerged as a beneficial therapy for heart failure (HF) patients. It has been shown to enhance cardiac pump function and increase exercise capacity in patients with HF who display wide QRS complex on their electrocardiogram. To date, few studies have assessed daily physical activity (PA) in CRT patients. The objective of this pilot study was to assess the impact of CRT on the physical function and daily PA of HF patients who met the standard indications for CRT implantation. METHODS: The daily PA of 18 CRT patients was measured using a SenseWear Armband for ∼3 d. Daily PA measurements included steps/d and time spent sedentary (≤1.5 metabolic equivalent tasks), in light PA (1.6-2.9 metabolic equivalent tasks), and in moderate-vigorous PA (≥3 metabolic equivalent tasks). To assess exercise capacity, a 6-min walk test was performed pre- and post-CRT. RESULTS: There was no significant change in the 6-min walk test distance from pre- to post-CRT (383 ± 99 m at baseline vs 402 ± 104 m post-CRT). There was a decrease in total steps/d from 3405 ± 2334 pre-CRT to 2553 ± 1692 post-CRT (P = .017). Furthermore, no significant changes were observed pre- to post-CRT with regard to the additional PA assessments. CONCLUSIONS: Our patients exhibited a sedentary lifestyle pre- and post-CRT. These findings underscore the need for a cardiac rehabilitation program that encourages post-CRT patients to decrease sedentary time.

Volume and Patterns of Physical Activity Across the Health and Heart Failure Continuum.

BACKGROUND: The benefits of regular physical activity (PA) are well documented in patients with heart failure (HF), however the amount and intensity of objectively measured PA and sedentary behaviour in HF with preserved (HFPEF) or reduced ejection fraction (HFREF) is not well known. METHODS: In a cross-sectional observational study the energy expenditure of 151 participants (HFPEF: n = 53; HFREF: n = 16; at-risk for HF: n = 48; control participants: n = 34) using SenseWear Mini Armbands (Body Media, Inc, Pittsburgh, PA) were monitored. PA outcomes included time spent in different PA intensities (light and moderate-vigorous PA), sedentary time, steps per day, total daily energy expenditure, PA energy expenditure, and the patterns of PA in bouts of ≥ 10 minutes of moderate-vigorous PA. RESULTS: The patients with HFPEF had the lowest volume of activity across the 4 groups. After adjusting for covariates, only steps per day remained significantly different across groups (P = 0.0005). A comparison of HFPEF vs HFREF indicated a higher amount of time in bouts of ≥ 10 minutes of moderate-vigorous PA for patients with HFREF (median, 2.4 [interquartile range, 0-13.5] vs 26 [3.7-46.8]; P = 0.0075). In the at-risk group, PA was lower than the recommended levels in the guidelines. CONCLUSIONS: Our findings suggest step count as the most robust outcome in evaluating daily PA in this population. Also, patients with HFPEF showed to be the least active group in the HF continuum. Monitoring volume and pattern of PA for those at risk of HF and patients with HFPEF could help to identify sedentary individuals and to develop tailored behavioural interventions for them.

Assessing the accuracy of algorithm-derived cardiorespiratory fitness in surgical patients: a prospective cohort study.

PURPOSE: To determine if a non-exercise algorithm-derived assessment of cardiorespiratory fitness (CRFA) accurately predicted estimated values obtained using a six-minute walk test (CRF6MWD) and the Duke Activity Status Index (CRFDASI). METHODS: Following research ethics board approval, an observational cohort study was conducted in selected, consenting patients undergoing elective surgery. Participants completed questionnaires assessing their self-reported exercise capacity. Their height, weight, waist circumference, and vital signs were measured. A six-minute walk test was performed twice with a 45-min rest interval between tests. The correlation between CRFA and both CRF6MWD and CRFDASI was determined. RESULTS: Two hundred forty-two participants were included. Mean age was 62 (range 45-88 yr); 150 (62%) were male, 87 (36%) self-reported walking or jogging > 16 km per week, and 49 (20%) were current smokers. The CRFA and CRF6MWD were highly correlated (Pearson r = 0.878; P < 0.001). CRFA and CRFDASI were less strongly correlated (Pearson r = 0.252; P < 0.001). Among patients capable of walking > 427 m in the six-minute walk test, CRFA, CRF6MWD, and CRFDASI were equivalent. CONCLUSION: A non-exercise algorithm can estimate cardiorespiratory fitness in patients presenting for elective surgery. The variables required to compute CRFA can be obtained in a clinic setting without the need to engage in formal exercise testing. Further evaluation of CRFA as a predictor of long-term outcome in patients is warranted.

Long-term Physical Activity Behavior After Completion of Traditional Versus Fast-track Cardiac Rehabilitation.

BACKGROUND: Despite the health benefits associated with regular physical activity (PA), many cardiac patients fail to maintain optimal levels of PA after completing cardiac rehabilitation (CR). The long-term impact of different CR delivery models on the PA habits of cardiac patients is not completely understood. OBJECTIVE: The purpose of this study is to use a multisensor accelerometer to compare the long-term impact of a traditional versus fast-track CR on the PA of patients with coronary artery disease 6 months after CR entry. METHODS: Forty-four participants attended either traditional (twice a week, 12 weeks; n = 24) or fast-track (once a week, 8 weeks; n = 20) CR. Exercise capacity (ie, 6-minute walk test distance) and PA were assessed at baseline and at 12 weeks and 6 months after CR entry. RESULTS: At 12 weeks, exercise capacity increased significantly in both groups and remained elevated by the 6-month follow-up. Sedentary time decreased from baseline to 12 weeks. However, at 6 months, it was comparable with the baseline level. There was no significant change in any other PA marker (ie, steps/day, time in light and moderate-vigorous PA) over the course of the study. CONCLUSIONS: Findings support the long-term effectiveness of CR on exercise capacity irrespective of the delivery model. However, participation in CR program, whether it be a traditional or fast-track CR exercise program, may not lead to long-term PA behavior change. Thus, CR participants may benefit from structured strategies that promote long-term PA adherence in addition to facilitating exercise capacity improvement.

Reliability and reactivity of the prefrontal hemodynamic responses in essential hypertension: a functional near infrared spectroscopy study.

Prefrontal (PFC) cerebral vasoreactivity may be altered in hypertension but has not been studied during postural change and carbon dioxide (CO2) rebreathing. In this study, a dual procedure of 5% CO2 rebreathing with positional change (standing to supine and reverse) was performed on normotensive (N = 24) and essential hypertensive males (N = 16) (18-55 years) to assess reliability of PFC responses using functional near infrared spectroscopy. The groups (matched on age levels, N = 13) were also compared on their hemodynamic reactivity (change of oxyhemoglobin or total hemoglobin as a function of change in end tidal CO2). Test-retest reliability within one session and 7 days later was moderate to high (intraclass correlation coefficient = .63-.901) in both normotensive and hypertensive groups for all hemodynamic measures; whereas reliability of reactivity measures for oxyhemoglobin and total hemoglobin was moderate (intraclass correlation coefficient = .68-.762). Functional near infrared spectroscopy-measured PFC hemodynamic responses are highly reproducible in normotensive and adult essential hypertensive males.

Quantity and Quality of Daily Physical Activity in Older Cardiac Patients.

BACKGROUND: Sedentary behaviour and the level of daily physical activity are of particular concern in cardiac patients, as diminished activity may be a strong predictor of mortality in this population. PURPOSE: In this study we assessed sedentary behaviour and the quantity and quality of daily physical activity among older cardiac patients who were at different stages of recovery following a cardiac event. DESIGN: We used a cross-sectional design and a convenience sampling technique. METHOD: Participants were recruited into three groups: an Acute group (n = 32), a Rehab group (n = 32), and a Maintain group (n = 29). Continuous minute by minute physical activity was assessed using the SenseWear Mini Armband, which was worn throughout each day for four consecutive days and provided data on steps/day, as well as time spent sedentary (waking time ≤ 1.5 METs), or in light (1.6-2.9 METs) or moderate-vigorous (≥ 3.0 METs) physical activity. FINDINGS: While the Rehab group accumulated more daily activity than the other two groups, they remained sedentary for approximately 70% of waking time. The quantity and quality of the activity in the Maintain group was comparable to that observed in the Acute group. CONCLUSIONS: Our observation of consistently elevated sedentary time regardless of whether the participant was entering, completing or were long removed from a formal cardiac rehabilitation program reinforces the need for cardiac rehabilitation nurse educators to both monitor routine daily activity and encourage coronary artery disease patients to adapt a lifestyle that is focused on reducing sedentary behaviour by incorporating planned exercise training and unstructured physical activity throughout the day.

Feasibility of a pedometer-based walking program for survivors of breast and head and neck cancer undergoing radiation therapy.

PURPOSE: This pilot study assessed the feasibility and acceptability of a pedometer-based walking program for people with breast cancer and head and neck cancer (HNC) undergoing radiation therapy treatment. METHODS: Participants were given a pedometer and prescribed a home-based walking program that included an individualized weekly step-count goal during the 3- to 5-week course of radiation therapy. Feasibility was determined by calculating recruitment rate, completion rate, and rate of adherence. Secondary outcomes included 6-minute walk test (6MWT) distance, step count, physical activity level, and psychological outcomes of depression, happiness, self-esteem, and sleep quality. RESULTS: A total of 21 participants were recruited. All participants completed the study; adherence to prescribed step counts was 91% at follow-up. Analysis found a significant improvement in happiness, as measured by the Oxford Happiness Questionnaire (mean difference 0.3, p=0.003), and a borderline significant improvement in 6MWT distance (mean difference 35 m, p=0.008). CONCLUSION: This pilot study demonstrated the feasibility of a pedometer-based walking program for survivors of breast cancer and HNC undergoing radiation therapy.

Objet: Cette étude pilote a évalué la faisabilité et l'acceptabilité d'un programme de marche à base de podomètre pour les personnes qui ont un cancer du sein et un cancer de la tête et du cou (CTC), et qui suivent une radiothérapie. Méthodes: Les participants ont reçu un podomètre et on leur a prescrit un programme de marche à domicile comportant un nombre personnalisé de pas par semaine à effectuer au cours de la radiothérapie d'une durée de 3 à 5 semaines. On a déterminé la faisabilité en calculant le taux d'inscription, le taux d'achèvement et le taux d'observation. Les résultats secondaires ont inclus la distance parcourue pendant le test de marche de 6 minutes (TM6M), le nombre de pas, le niveau d'activité physique (AP) et les résultats psychologiques liés à la dépression, au bonheur, à l'estime de soi et à la qualité du sommeil. Résultats: Au total, 21 participants ont été recrutés. Tous les participants ont terminé l'étude et avaient effectué le nombre de pas prescrit dans une proportion de 91% au moment du suivi. L'analyse a révélé une amélioration importante du bonheur mesuré au moyen du questionnaire d'Oxford sur le bonheur (différence moyenne de 0,3, p=0,003) et une amélioration significative limite de la distance parcourue pendant le TM6M (différence moyenne de 35 m, p=0,008). Conclusion: Cette étude pilote a démontré la faisabilité d'un programme de marche à base de podomètre pour les survivants d'un cancer du sein et d'un CTC qui suivent une radiothérapie.

The sustainability of exercise capacity changes in home versus center-based cardiac rehabilitation.

PURPOSE: Although participation in either center- or home-based cardiac rehabilitation (CR) can improve exercise capacity, the sustainability of this improvement following completion of the CR program is challenging. The purpose of this study was to compare the immediate and 1-year effectiveness of center- versus home-based CR on exercise capacity in cardiac patients who were given the choice of participating in a center-based or home-based CR program. METHODS: This was a retrospective study, which relied on the database from a large multidisciplinary CR program. A sample of 3488 cardiac patients participated either in center-based (n = 2803) or home-based (n = 685) CR. Participants underwent exercise testing at baseline, after 12 weeks of CR and again 1 year after completion of the CR programs. RESULTS: Following CR, exercise capacity (ie, peak metabolic equivalents [METs]) increased significantly in both groups (P < .05). From post-CR to the 1-year followup, exercise capacity remained unchanged in home-based CR participants (P = .183), whereas the center-based CR group demonstrated a decline in exercise capacity (P < .05). CONCLUSIONS: Although at the 1-year followup exercise capacity decreased in the center-based group, the observed decline did not seem to be clinically significant. The present findings indicate that when the patients were given a choice as to the delivery model (center- vs home-based) used for their CR program, they were relatively successful in retaining the improvement in exercise capacity 1 year post-CR irrespective of the exact location for their exercise training.

Impact of supervised exercise rehabilitation on daily physical activity of cardiopulmonary patients.

OBJECTIVES: The purpose of this study was to assess the impact of exercise rehabilitation (ER) on the daily physical activity (PA) of cardiopulmonary patients. BACKGROUND: The impact of ER programs on the objectively measured quantity and quality of daily PA in cardiopulmonary patients is not completely understood. METHODS: Participants' exercise capacity and PA were measured at baseline and at the end of the ER program (n = 37). RESULTS: Exercise capacity was higher at the end of the ER. Participants' sedentary time decreased while time spent in light PA increased; however, time spent in moderate-vigorous PA (MVPA) did not change. There was an increase in steps/day (>1.5 METs) and PA energy expenditure (PAEE) (>1.5 METs); whereas steps/day (≥3METs) and PAEE (≥3 METs) remained unchanged. CONCLUSIONS: Findings imply that changes in daily PA in patients participating in ER occur in activities where the EE is in light intensity rather than in MVPA.

Feasibility and efficacy of a 12-week supervised exercise intervention for colorectal cancer survivors.

Exercise training improves health-related physical fitness and patient-reported outcomes in cancer survivors, but few interventions have targeted colorectal cancer (CRC) survivors. This investigation aimed to determine the feasibility and efficacy of a 12-week supervised exercise training program for CRC survivors. Feasibility was assessed by tracking participant recruitment, loss to follow-up, assessment completion rates, participant evaluation, and adherence to the intervention. Efficacy was determined by changes in health-related physical fitness. Over a 1-year period, 72 of 351 (21%) CRC survivors screened were eligible for the study and 29 of the 72 (40%) were enrolled. Two participants were lost to follow-up (7%) and the completion rate for all study assessments was ≥93%. Mean adherence to the exercise intervention was 91% (standard deviation = ±18%), with a median of 98%. Participants rated the intervention positively (all items ≥ 6.6/7) and burden of testing low (all tests ≤ 2.4/7). Compared with baseline, CRC survivors showed improvements in peak oxygen uptake (mean change (MC) = +0.24 L·min(-1), p < 0.001), upper (MC = +7.0 kg, p < 0.001) and lower (MC = +26.5 kg, p < 0.001) body strength, waist circumference (MC = -2.1 cm, p = 0.005), sum of skinfolds (MC = -7.9 mm, p = 0.006), and trunk forward flexion (MC = +2.5 cm, p = 0.019). Exercise training was found to be feasible and improved many aspects of health-related physical fitness in CRC survivors that may be associated with improved quality of life and survival in these individuals.

Exercise training improves aerobic capacity, muscle strength, and quality of life in renal transplant recipients.

Renal transplant recipients (RTR) have reduced peak aerobic capacity, muscle strength, arterial function and an unfavorable cardiovascular disease risk (CVD) profile. This study compared the effects of 12 weeks of supervised endurance and strength training (EST, n = 16) versus usual care (UC, n = 15) on peak aerobic capicity, cardiovascular and skeletal muscle function, CVD risk profile, and quality of life (QOL) in RTR (55 ± 13 years). Peak aerobic capacity and exercise hemodynamics, arterial compliance, 24-h blood pressure, muscle strength, lean body mass, CVD risk score, and QOL were assessed before and after 12 weeks. The change in peak aerobic capacity (EST: 2.6 ± 3.1 vs. UC: -0.5 ± 2.5 mL/(kg·min)), cardiac output (EST: 1.7 ± 2.6 vs. UC: -0.01 ± 0.8 L/min), leg press (EST: 48.7 ± 34.1 vs. UC: -10.5 ± 37.7 kg) and leg extension strength (EST: 9.5 ± 10.3 vs. UC: 0.65 ± 5.5 kg) improved significantly after EST compared with UC. The overall change in QOL improved significantly after 12 weeks of EST compared with UC. No significant difference was found between groups for lean body mass, arterial compliance, 24-h blood pressure or CVD risk score. Supervised EST is an effective intervention to improve peak exercise aerobic capacity and cardiac output, muscle strength and QOL in clinically stable RTR.

Effect of modality on cardiopulmonary exercise testing in male and female COPD patients.

The purpose of this study was to examine the physiological responses to treadmill and cycle cardiopulmonary exercise testing (CPET) in male and female COPD patients. Fifty-five patients [28 males (FEV1=58.2±19.5% predicted), and 27 females (FEV1=65.3±16.6% predicted)] completed a treadmill and a cycle CPET in random order on two separate days. Respiratory and cardiovascular data were obtained. Compared to the cycle CPET, the treadmill elicited greater peak power output and peak oxygen uptake, while arterial saturation at peak exercise was lower with the treadmill; however, there were no differences between the responses in men and women. No differences were observed in heart rate, ventilation, tidal volume/breathing frequency, inspiratory capacity, or dyspnea responses between modalities or sex. The physiological responses between treadmill and cycle CPET protocols are largely similar for both men and women with COPD, indicating that either modality can be used in mild/moderate COPD patients.

An experimental assessment of the influence of exercise versus social implementation intentions on physical activity during and following pulmonary rehabilitation.

Techniques to increase physical activity among pulmonary rehabilitation patients outside of the rehabilitation context are warranted. Implementation intentions are a strategy used to initiate goal-directed behaviour, and have been found to be useful in other populations. This study compared the long-term effects of exercise and social implementation intentions interventions on objectively measured physical activity in 40 pulmonary rehabilitation patients randomly assigned to condition. Repeated measures ANOVAs found that those in the exercise implementation intentions group took more steps (p = .007) at the end of pulmonary rehabilitation than those in the social implementation intentions group. Improvements attained by the exercise group during the intervention were not maintained 6-months following rehabilitation. Implementation intentions targeting physical activity appear to have positive short term effects on physical activity, although the long term effects are less consistent. This may be due in part to methods used to assess physical activity behaviour.

SenseWear Armband and Stroke: Validity of Energy Expenditure and Step Count Measurement during Walking.

The purpose of this study was to test the validity of the SenseWear Pro Armband (SWA) for the measurement of energy expenditure (EE) and step count against a criterion in persons with stroke. Twelve participants with chronic stroke (mean age 64.2 ± 10.4 years; mean gait speed 0.67 ± 0.25 m/sec) completed two trials of a six-minute walk test, while wearing a SenseWear Armband (SWA) on each arm and being continuously monitored using a portable metabolic cart. Agreement between estimates of energy expenditure from the SWA and the metabolic cart was fair for the armband on the hemiplegic arm (intraclass correlation cefficient (ICC) = 0.586) and good for the armband on the unaffected arm (ICC = 0.702). Agreement between the SWA estimate of step count, and step count as measured by the Step Activity Monitor was poor (ICC < 0.352), with significant underestimation by the SWA. Our results show that, for these moderately impaired persons with stroke, the SWA should be used with caution for the measurement of energy expenditure and should not be used to measure step count.

Exercise rehabilitation for chronic heart failure patients with cardiac device implants.

In the past decade a significant development in the management and rehabilitation of people with chronic heart failure (CHF) has been the utilization of cardiac devices. The use of biventricular pacemakers, referred to as Cardiac Resynchronization Therapy (CRT) can yield improvements in functional abilities for a select group of CHF patients and the inclusion of implantable cardiac defibrillators (ICDs) may reduce the risk of sudden death. This review provides physical therapists with a basic understanding of how to prescribe exercise for people with CHF who have these device implants.

Impact of peak oxygen uptake and muscular fitness on the performance of activities of daily living in patients with chronic obstructive pulmonary disease.

PURPOSE: Chronic obstructive pulmonary disease (COPD) is a progressively debilitating disease, which, over time, may compromise patient ability to perform activities of daily living (ADL). The purpose of this study was to examine the relationships between selected parameters of physical fitness and performance of ADL in COPD patients. METHODS: A convenience sample of 23 COPD patients (11 men and 12 women, age 6869 years) was studied at the conclusion of an exercise rehabilitation program. Patients were assessed using the Continuous Scale Physical Functional Performance 10 Test (PFP-10) battery, chest press, leg press, and a symptom limited graded exercise test. RESULTS: The PFP-10 global score was 54 ± 12, and 11 patients fell below a global score of 57, which has been established as the threshold for independence. Peak oxygen uptake (VO(2peak)) was 20 ± 4 mL·kg(-1)·min(-1), the forced expiratory volume in 1 second/forced expiratory volume ratio was 0.58 ± 0.12, grip strength was 61 ± 16 kg (both hands), and chest press and leg press were 4 ± 3 and 12 ± 7 kg/kg body weight, respectively. The associations between the PFP-10 VO(2peak) and leg press were modest (r = 0.501, P = .014; and r = 0.547, P = .008) as was grip strength (r = 0.418, P = .047). There was no association between the PFP-10 and forced expiratory volume, forced expiratory volume in 1 second/forced vital capacity, or chest press (r = -20.040, P = .856; r = 20.212, P = .330; and r = 0.120, P = .595), respectively. CONCLUSION: The results of this investigation suggest that lower body strength is important in optimizing ADL performance in COPD patients.

Cardiac resynchronization therapy modulation of exercise left ventricular function and pulmonary O2 uptake in heart failure.

To better understand the mechanisms contributing to improved exercise capacity with cardiac resynchronization therapy (CRT), we studied the effects of 6 mo of CRT on pulmonary O(2) uptake (Vo(2)) kinetics, exercise left ventricular (LV) function, and peak Vo(2) in 12 subjects (age: 56 ± 15 yr, peak Vo(2): 12.9 ± 3.2 ml·kg(-1)·min(-1), ejection fraction: 18 ± 3%) with heart failure. We hypothesized that CRT would speed Vo(2) kinetics due to an increase in stroke volume secondary to a reduction in LV end-systolic volume (ESV) and that the increase in peak Vo(2) would be related to an increase in cardiac output reserve. We found that Vo(2) kinetics were faster during the transition to moderate-intensity exercise after CRT (pre-CRT: 69 ± 21 s vs. post-CRT: 54 ± 17 s, P < 0.05). During moderate-intensity exercise, LV ESV reserve (exercise - resting) increased 9 ± 7 ml (vs. a 3 ± 9-ml decrease pre-CRT, P < 0.05), and steady-state stroke volume increased (pre-CRT: 42 ± 8 ml vs. post-CRT: 61 ± 12 ml, P < 0.05). LV end-diastolic volume did not change from rest to steady-state exercise post-CRT (P > 0.05). CRT improved heart rate, measured as a lower resting and steady-state exercise heart rate and as faster heart rate kinetics after CRT (pre-CRT: 89 ± 12 s vs. post-CRT: 69 ± 21 s, P < 0.05). For peak exercise, cardiac output reserve increased significantly post-CRT and was 22% higher at peak exercise post-CRT (both P < 0.05). The increase in cardiac output was due to both a significant increase in peak and reserve stroke volume and to a nonsignificant increase in heart rate reserve. Similar patterns in LV volumes as moderate-intensity exercise were observed at peak exercise. Cardiac output reserve was related to peak Vo(2) (r = 0.48, P < 0.05). These findings demonstrate the chronic CRT-mediated cardiac factors that contribute, in part, to the speeding in Vo(2) kinetics and increase in peak Vo(2) in clinically stable heart failure patients.

Effect of acute high-intensity interval exercise on postexercise biventricular function in mild heart failure.

We studied the acute effect of high-intensity interval exercise on biventricular function using cardiac magnetic resonance imaging in nine patients [age: 49 ± 16 yr; left ventricular (LV) ejection fraction (EF): 35.8 ± 7.2%] with nonischemic mild heart failure (HF). We hypothesized that a significant impairment in the immediate postexercise end-systolic volume (ESV) and end-diastolic volume (EDV) would contribute to a reduction in EF. We found that immediately following acute high-intensity interval exercise, LV ESV decreased by 6% and LV systolic annular velocity increased by 21% (both P < 0.05). Thirty minutes following exercise (+30 min), there was an absolute increase in LV EF of 2.4% (P < 0.05). Measures of preload, left atrial volume and LV EDV, were reduced immediately following exercise. Similar responses were observed for right ventricular volumes. Early filling velocity, filling rate, and diastolic annular velocity remained unchanged, while LV untwisting rate increased 24% immediately following exercise (P < 0.05) and remained 18% above baseline at +30 min (P < 0.05). The major novel findings of this investigation are 1) that acute high-intensity interval exercise decreases the immediate postexercise LV ESV and increases LV EF at +30 min in patients with mild HF, and this is associated with a reduction in LV afterload and maintenance of contractility, and 2) that despite a reduction in left atrial volume and LV EDV immediately postexercise, diastolic function is preserved and may be modulated by enhanced LV peak untwisting rate. Acute high-intensity interval exercise does not impair postexercise biventricular function in patients with nonischemic mild HF.