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.

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.

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.

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.

Impact of cardiac rehabilitation on the ability of elderly cardiac patients to perform common household tasks.

PURPOSE: The consequences of coronary artery disease may significantly limit functional independence of elderly patients. While cardiac rehabilitation (CR) exercise programs have been shown to improve health outcomes such as exercise capacity, little is known about the impact such programs have on daily functional abilities. The purpose of this study was to determine the impact of CR on ability of elderly patients to perform common household tasks. METHODS: Twenty-two postmyocardial infarction patients (10 women and 12 men; age 75 ± 6.3 years) were studied. Patients were tested pre-CR and post-CR. Physical function (PF) was assessed using the Continuous Scale Physical Function Performance 10 test battery, which includes 10 everyday tasks that progress from easy (personal tasks) to moderate (household tasks) to difficult (mobility tasks). Self-reported PF was measured using the Medical Outcomes Survey Short Form 36-Item questionnaire. RESULTS: Post-CR, the global Continuous Scale Physical Function Performance 10 score increased significantly (57 + 12 vs 50 ± 16; P = .002). Prior to CR, 7 patients scored at or above the threshold for independent living, as defined by a global score of 57 or more units; however, post-CR, 12 patients scored above the threshold. There was no change in self-reported PF, post-CR. CONCLUSIONS: A 20-session exercise-based CR program significantly enhanced elderly patient ability to live independently by improving ability to perform common household tasks.

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.

Oxygen uptake kinetics: associations with ambulatory activity and physical functional performance in stroke survivors.

OBJECTIVE: To explore the associations amongst the on-and-off kinetics time constants, ambulatory activity outcomes, and physical functional performance in stroke survivors. DESIGN: Cross-sectional, case control study. SUBJECTS: Ten stroke survivors (time since stroke: mean 7.5 years (standard deviation 8.3); gender: 4 males, 6 females) and 10 control subjects matched for age and physical activity level. METHODS: Oxygen uptake kinetics (on-and-off kinetics) were measured using a submaximal exercise test with a recumbent cycle. The continuous-scale physical functional performance test was used to measure functional ability. Ambulatory activity outcomes including steps per day, number of activity bouts and length of activity bouts were measured using a Step Activity Monitor. RESULTS AND CONCLUSION: Shorter activity bouts were significantly associated with longer off-kinetics time constants in stroke survivors (or longer time to recover from an exercise bout). Future research may test the effect of activity interventions designed to increase the length of activity bouts on-kinetics outcomes and functional ability.

Cardiac reserve and pulmonary gas exchange kinetics in patients with stroke.

BACKGROUND AND PURPOSE: Cardiovascular and pulmonary factors contributing to impaired peak oxygen uptake (VO2) in patients with stroke (SP) are not well known. We assessed cardiovascular function, pulmonary gas exchange, and ventilation in SP and healthy age, gender, and activity-matched control subjects. METHODS: Ten hemiparetic SP and 10 control subjects were enrolled. Subjects completed cycle ergometry testing to assess peak and reserve VO2, carbon dioxide production, ventilation (tidal volume; breathing frequency; minute ventilation), and cardiac output. VO2, carbon dioxide production, and minute ventilation were measured throughout peak exercise recovery (off-kinetics) and at exercise onset (on-kinetics) along with heart rate during low-level exercise. RESULTS: Peak VO2 was 43% lower (P<0.001) in SP secondary to reduced peak and reserve cardiac output and minute ventilation. The impaired cardiac output reserve (P<0.001) was due to a 34% lower heart rate reserve (P=0.001). The impaired minute ventilation reserve (P=0.013) was due to a 41% lower tidal volume reserve (P=0.009). Stroke volume and breathing frequency reserve were preserved. VO2 off-kinetics were 29% slower in SP (P<0.001) and related to peak VO2 (R=-0.72, P<0.001) and peak cardiac output (R=-0.75, P<0.001) for the study group. Additionally, carbon dioxide production (P=0.016) and minute ventilation (P=0.023) off-kinetics were prolonged in SP. VO2 on-kinetics were 29% slower (P=0.031) during low-level exercise in SP. CONCLUSIONS: The impaired peak VO2 in SP is secondary to a decline in peak and reserve cardiac output and ventilation. Prolonged VO2 kinetics in SP are associated in part with deconditioning and may be mediated by reduced O2 availability and/or the rate of muscle O2 use.

Pulmonary oxygen uptake and heart rate kinetics during the six-minute walk test in transplant recipients.

BACKGROUND: The effect of organ transplantation on arterial compliance, pulmonary oxygen uptake (VO2p) and heart rate kinetics during the 6-minute walk test (6-MWT) remains unknown. METHODS: Twenty-two thoracic (heart and/or lung) organ transplant recipients (TOTR, 51+/-12 years) and 30 abdominal (kidney, kidney-pancreas, or liver) organ transplant recipients (AOTR, 46+/-11 years) from the 2006 Canadian Transplant Games, and 37 healthy controls (HC) completed a 6-MWT. VO2p, heart rate kinetics, and arterial compliance were determined. RESULTS: The 6-MWT distance and highest VO2p were significantly lower in TOTR and AOTR versus HC. The highest 6-MWT heart rate was lower in TOTR (11%) and AOTR (13%) versus HC. VO2p kinetics were slower in TOTR (52+/-11 sec, P