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Chin-Moi Chow

Publications and source records attributed to Chin-Moi Chow.

12 recordsLinked to original sources
PubMed2006

Worksite intervention effects on physical health: a randomized controlled trial.

Overweight and physical inactivity are risk factors for increased disease burden and health care expenditure. Well-designed studies are still needed to determine the treatment efficacy of worksite interventions targeting such risk factors. This randomized controlled trial was conducted at one of Australia's casinos in 2002-2003, to investigate the effects of a comprehensive exercise and lifestyle intervention on physical fitness. Only 6.4% of the workforce expressed interest in being study participants. Seventy-three employees (aged 32 +/- 8 years, 51% overweight/obese, 73% shift workers and 52% women) were recruited and randomized to treatment or wait-list control groups for 24 weeks, 44 of whom completed the intervention. Components of the intervention include supervised moderate-to-high intensity exercise including combined aerobic (at least 20 min duration 3 days/week) and weight-training (for an estimated 30 min completed 2-3 days/week), and dietary/health education (delivered via group seminars, one-on-one counselling and literature through the provision of a worksite manual). ANCOVA, by intention-to-treat and of study completers, found significant between-group differences in the mean waist circumference and predicted maximal oxygen uptake (VO2max), favouring the intervention, but effects were concentrated in one subject. For study completers, between-group differences in the mean waist circumference (82.3 +/- 9.2 versus 90.5 +/- 17.8 cm, p = 0.01) and predicted VO2max (47 versus 41 ml/kg/min, p < 0.001) remained significant without the outlier, favouring the intervention. Higher intervention compliance predicted greater improvements in physical fitness. No significant effects on body mass or body mass index were found. This worksite intervention significantly improved waist circumference and aerobic fitness in healthy but sedentary employees, most of whom were shift workers. Worksite interventions have the potential to counter the increasing burden of overweight and obesity, particularly visceral adiposity, as well as physical inactivity; however, substantial barriers to adoption/adherence need to be overcome for greater feasibility and impact on employee physical health.

Adult↗
PubMed2006

A modified postural drainage position produces less cardiovascular stress than a head-down position in patients with severe heart disease: a quasi-experimental study.

QUESTION: Does a modified postural drainage position (horizontal) produce less cardiovascular and respiratory stress than a head-down postural drainage position (30 degrees) in people with severe heart disease? DESIGN: A quasi-experimental study. PARTICIPANTS: Thirty-one patients (mean age 69 years, SD 13) with severe left ventricular systolic dysfunction (mean ejection fraction 23%, SD 7) who were stable, receiving regular medication and free of acute respiratory illness. INTERVENTION: Two manoeuvres were performed--one from long sitting to a modified (horizontal) postural drainage position, and one from long sitting to a head-down (30 degrees) postural drainage position. OUTCOME MEASURES: Cardiovascular responses examined were blood pressure, sphygmocardiographic indices, and cardiac rhythm. Respiratory responses examined were respiratory rate, transcutaneous arterial oxyyhaemoglobin saturation, and dyspnoea. RESULTS: Three participants were intolerant to the postural drainage positions--two during head-down and one during modified positioning. The remaining 28 participants maintained their resting cardiac rhythm and did not complain of chest pain or dyspnoea. The changes in cardiovascular responses during the sitting to head-down postural drainage manoeuvre in the tolerant participants were significantly greater (p < 0.05) than the changes during the sitting to the modified postural drainage manoeuvre for most of the sphygmocardiographic indices. In contrast, there were no significant respiratory responses to either postural drainage manoeuvre. CONCLUSION: Modified positioning is associated with less cardiovascular stress than head-down positioning, yet for most patients with severe heart disease, both positions are generally well tolerated. For a subset of these patients, either position may be inappropriate. This suggests that modified positioning should be attempted first but that a head-down position may be attempted if the modified position proves ineffective.

Aged↗
PubMed2006

Worksite intervention effects on sleep quality: a randomized controlled trial.

Employees with sleep disturbance are at increased risk of disease. Exercise is believed to be effective for improving sleep quality, but few studies have been conducted. This study investigated the effects of a 24-week worksite exercise/behavioral intervention on self-rated sleep quality, via the Pittsburgh Sleep Quality Index (PSQI), in 73 employees. Greater post-test improvements in the PSQI (-2.0 +/- 2.6 vs. -1.3 +/- 2.7 points, p = .006, and -16 +/- 61 vs. -1 +/- 76%, p = .02) were found in treatment versus controls, and in women versus men (by -2.7 points [-5.0 to -0.3 points, p = .03], and by -72% [-142 to -2%, p = .04]). Similar results were found in the shift worker subgroup. Changes in sleep scores were not significantly related to baseline characteristics, changes in psychological health or quality-of-life scores, or level of exercise compliance.

Adult↗
PubMed2005

Sleep disturbance at simulated altitude indicated by stratified respiratory disturbance index but not hypoxic ventilatory response.

At high altitudes, the clinically defined respiratory disturbance index (RDI) and high hypoxic ventilatory response (HVR) have been associated with diminished sleep quality. Increased RDI has also been observed in some athletes sleeping at simulated moderate altitude. In this study, we investigated relationships between the HVR of 14 trained male endurance cyclists with variable RDI and sleep quality responses to simulated moderate altitude. Blood oxygen saturation (SpO2%), heart rate, RDI, arousal rate, awakenings, sleep efficiency, rapid eye movement (REM) sleep, non-REM sleep stages 1, 2 and slow wave sleep as percentages of total sleep time (%TST) were measured for two nights at normoxia of 600 m and one night at a simulated altitude of 2,650 m. HVR and RDI were not significantly correlated with sleep stage, arousal rate or awakening response to nocturnal simulated altitude. SpO2 was inversely correlated with total RDI (r = -0.69, P = 0.004) at simulated altitude and with the change in arousal rate from normoxia (r = -0.65, P = 0.02). REM sleep response to simulated altitude correlated with the change, relative to normoxia, in arousal (r = -0.63, P = 0.04) and heart rate (r = -0.61, P = 0.04). When stratified, those athletes at altitude with RDI >20 h(-1) (n = 4) and those with <10 h(-1) (n = 10) exhibited no difference in HVR but the former had larger falls in SpO2 (P = 0.05) and more arousals (P = 0.03). Neither RDI (without stratification) nor HVR were sufficiently sensitive to explain any deterioration in REM sleep or arousal increase. However, the stratified RDI provides a basis for determining potential sleep disturbance in athletes at simulated moderate altitude.

Adult↗
PubMed2005

Cardiovascular responses to short-term head-down positioning in healthy young and older adults.

BACKGROUND AND PURPOSE: Isolated head-down postural drainage is assumed to acutely load the cardiovascular system. Consequently, it is considered a relative contraindication in the presence of severe cardiovascular disease. Evidence demonstrating that the head-down manoeuvre as used by physiotherapists does significantly load the cardiovascular system is lacking. The present study documents the cardiovascular responses t short-term 30 degrees head-down positioning in healthy subjects. The results are a point of reference for respiratory patients with and without cardiovascular disease. METHOD: A quasi-experimental research design was used, with multiple measurements obtained at rest (long sitting and in the head-down position. Twenty-one young subjects (mean age 25 years (standard deviation, (SD) 3 years)) and 19 older subjects (mean age 66 years (SD 6 years)) were studied. Applanation tonometry and sphygmocardiography were used to measure temporal and pressure variables, and indices that estimate myocardial work and coronary blood flow. RESULTS: Absolute differences existed between the two age groups for all variables at rest (p < 0.001). No age-time interaction was observed for any variable in the head-down position (p > 0.05). Serial measures in the head-down position did not vary across time (p > 0.05). Small (<9%) but significant (p < or = 0.02) decreases in heart rate, relative diastolic duration, mean arterial blood pressure and diastolic time indices, and small (<12%) but significant (p < or = 0.002) increases in cardiac cycle time, ejection duration (relative and absolute) and absolute diastolic duration were observed in the head-down position compared with rest. A small (9%) but significant (p < 0.001) fall in the sub-endocardial viability ratio occurred in the head down position. CONCLUSION: The findings have little consequence in health, but they suggest that head-down postural drainage may be of concern for chest physiotherapy recipients with reduced cardiac reserve or impaired barorefilex function.

Adult↗
PubMed2004

Hypoxic ventilatory response is correlated with increased submaximal exercise ventilation after live high, train low.

This study tested the hypothesis that live high, train low (LHTL) would increase submaximal exercise ventilation (V(E)) in normoxia, and the increase would be related to enhanced hypoxic ventilatory response (HVR). Thirty-three cyclists/triathletes were divided into three groups: 20 consecutive nights of hypoxia (LHTLc, n = 12), 20 nights of intermittent hypoxia (4x5-night 'blocks' of hypoxia interspersed by two nights of normoxia, LHTLi, n = 10), or control (CON, n = 11). LHTLc and LHTLi slept 8-10 h per night in normobaric hypoxia (2,650 m), and CON slept under ambient conditions (600 m). Resting, isocapnic HVR (DeltaV(E)/Deltablood oxygen saturation) was measured in normoxia before (PRE) and after 15 nights (N15) hypoxia. Submaximal cycle ergometry was conducted PRE and after 4, 10, and 19 nights of hypoxia (N4, N10, and N19 respectively). Mean submaximal exercise V(E) was increased (P < 0.05) from PRE to N4 in LHTLc [74.4 (5.1) vs 80.0 (8.4) l min(-1); mean (SD)] and in LHTLi [69.0 (7.5) vs 76.9 (7.3) l min(-1)] and remained elevated in both groups thereafter, with no changes observed in CON at any time. Prior to LHTL, submaximal V(E) was not correlated with HVR, but this relationship was significant at N4 (r = 0.49, P = 0.03) and N19 (r = 0.77, P < 0.0001). Additionally, the increases in submaximal V(E) and HVR from PRE to N15-N19 were correlated (r = 0.51, P = 0.02) for the pooled data of LHTLc and LHTLi. These results suggest that enhanced hypoxic chemosensitivity contributes to increased exercise V(E) in normoxia following LHTL.

Acclimatization↗
PubMed2004

An effective exercise-based intervention for improving mental health and quality of life measures: a randomized controlled trial.

OBJECTIVES: This study investigates the effectiveness of 24-week aerobic and weight-training exercise plus behavior modification for mental health and quality of life (QOL) outcomes. METHODS: Mental health and QOL data was collected using the Depression Anxiety and Stress Scales and SF-36 Health Status Survey, respectively. Employees from a single work-site were randomized into either treatment or wait-list control groups. RESULTS: Mental Health (P = 0.005), Vitality (P < 0.001), General Health (P = 0.009), Bodily Pain (P = 0.005), Physical Functioning (P = 0.004), Depression (P = 0.048), and Stress (P = 0.036) scales significantly improved for the treatment group compared to wait-list controls after 24 weeks. CONCLUSIONS: Multimodal exercise is as effective as other single-modality exercise treatments for depressive symptoms and, in contrast to other studies, does improve stress symptoms and QOL outcomes.

Adult↗
PubMed2003

Effects of live high, train low hypoxic exposure on lactate metabolism in trained humans.

We determined the effect of 20 nights of live high, train low (LHTL) hypoxic exposure on lactate kinetics, monocarboxylate lactate transporter proteins (MCT1 and MCT4), and muscle in vitro buffering capacity (betam) in 29 well-trained cyclists and triathletes. Subjects were divided into one of three groups: 20 consecutive nights of hypoxic exposure (LHTLc), 20 nights of intermittent hypoxic exposure [four 5-night blocks of hypoxia, each interspersed with 2 nights of normoxia (LHTLi)], or control (Con). Rates of lactate appearance (Ra), disappearance (Rd), and oxidation (Rox) were determined from a primed, continuous infusion of l-[U-14C]lactic acid tracer during 90 min of steady-state exercise [60 min at 65% peak O2 uptake (VO(2 peak)) followed by 30 min at 85% VO(2 peak)]. A resting muscle biopsy was taken before and after 20 nights of LHTL for the determination of betam and MCT1 and MCT4 protein abundance. Ra during the first 60 min of exercise was not different between groups. During the last 25 min of exercise at 85% VO(2 peak), Ra was higher compared with exercise at 65% of VO(2 peak) and was decreased in LHTLc (P < 0.05) compared with the other groups. Rd followed a similar pattern to Ra. Although Rox was significantly increased during exercise at 85% compared with 65% of VO(2 peak), there were no differences between the three groups or across trials. There was no effect of hypoxic exposure on betam or MCT1 and MCT4 protein abundance. We conclude that 20 consecutive nights of hypoxia exposure decreased whole body Ra during intense exercise in well-trained athletes. However, muscle markers of lactate metabolism and pH regulation were unchanged by the LHTL intervention.

Acid-Base Equilibrium↗
PubMed2002

Living high-training low increases hypoxic ventilatory response of well-trained endurance athletes.

This study determined whether "living high-training low" (LHTL)-simulated altitude exposure increased the hypoxic ventilatory response (HVR) in well-trained endurance athletes. Thirty-three cyclists/triathletes were divided into three groups: 20 consecutive nights of hypoxic exposure (LHTLc, n = 12), 20 nights of intermittent hypoxic exposure (four 5-night blocks of hypoxia, each interspersed with 2 nights of normoxia, LHTLi, n = 10), or control (Con, n = 11). LHTLc and LHTLi slept 8-10 h/day overnight in normobaric hypoxia (approximately 2,650 m); Con slept under ambient conditions (600 m). Resting, isocapnic HVR (DeltaVE/DeltaSp(O(2)), where VE is minute ventilation and Sp(O(2)) is blood O(2) saturation) was measured in normoxia before hypoxia (Pre), after 1, 3, 10, and 15 nights of exposure (N1, N3, N10, and N15, respectively), and 2 nights after the exposure night 20 (Post). Before each HVR test, end-tidal PCO(2) (PET(CO(2))) and VE were measured during room air breathing at rest. HVR (l. min(-1). %(-1)) was higher (P < 0.05) in LHTLc than in Con at N1 (0.56 +/- 0.32 vs. 0.28 +/- 0.16), N3 (0.69 +/- 0.30 vs. 0.36 +/- 0.24), N10 (0.79 +/- 0.36 vs. 0.34 +/- 0.14), N15 (1.00 +/- 0.38 vs. 0.36 +/- 0.23), and Post (0.79 +/- 0.37 vs. 0.36 +/- 0.26). HVR at N15 was higher (P < 0.05) in LHTLi (0.67 +/- 0.33) than in Con and in LHTLc than in LHTLi. PET(CO(2)) was depressed in LHTLc and LHTLi compared with Con at all points after hypoxia (P < 0.05). No significant differences were observed for VE at any point. We conclude that LHTL increases HVR in endurance athletes in a time-dependent manner and decreases PET(CO(2)) in normoxia, without change in VE. Thus endurance athletes sleeping in mild hypoxia may experience changes to the respiratory control system.

Acclimatization↗
PubMed2002

Respiratory events and periodic breathing in cyclists sleeping at 2,650-m simulated altitude.

We examined the initial effect of sleeping at a simulated moderate altitude of 2,650 m on the frequency of apneas and hypopneas, as well as on the heart rate and blood oxygen saturation from pulse oximetry (SpO2) during rapid eye movement (REM) and non-rapid eye movement (NREM) sleep of 17 trained cyclists. Pulse oximetry revealed that sleeping at simulated altitude significantly increased heart rate (3 +/- 1 beats/min; means +/- SE) and decreased SpO2 (-6 +/- 1%) compared with baseline data collected near sea level. In response to simulated altitude, 15 of the 17 subjects increased the combined frequency of apneas plus hypopneas from baseline levels. On exposure to simulated altitude, the increase in apnea was significant from baseline for both sleep states (2.0 +/- 1.3 events/h for REM, 9.9 +/- 6.2 events/h for NREM), but the difference between the two states was not significantly different. Hypopnea frequency was significantly elevated from baseline to simulated altitude exposure in both sleep states, and under hypoxic conditions it was greater in REM than in NREM sleep (7.9 +/- 1.8 vs. 4.2 +/- 1.3 events/h, respectively). Periodic breathing episodes during sleep were identified in four subjects, making this the first study to show periodic breathing in healthy adults at a level of hypoxia equivalent to 2,650-m altitude. These results indicate that simulated moderate hypoxia of a level typically chosen by coaches and elite athletes for simulated altitude programs can cause substantial respiratory events during sleep.

Adult↗
PubMedDate not supplied

Physiotherapist attitudes and practices regarding head-down and modified postural drainage in the presence of heart disease.

Modification of chest physiotherapy interventions is recommended for patients with concomitant respiratory and cardiac diseases. What modifications are necessary and for whom, and what strategies physiotherapists adopt when heart disease is present, have not been investigated. Consequently, few guidelines exist. A questionnaire survey was conducted to identify attitudes and practices of senior cardiopulmonary physiotherapists (SCPP) and "other" physiotherapists (OP) regarding modified and head-down postural drainage (HDPD) when heart disease is present. The overall response rate was 44% (178/407); the response rate from SCPP (78%, 50/64) was higher than from OP (37%, 128/343). Major findings included that: postural modification in the presence of heart disease is common and is not reserved for patients with severe disease; the most commonly adopted modified position is the horizontal; and that the rationale for modification is commonly based on the assumptions that the cardiovascular load is less and, thus, adverse outcomes will be avoided. In the main, the response patterns for both groups were similar, but some between-group differences were found. The findings overall suggest physiotherapists adopt a cautious approach to HDPD when heart disease is present. Whether this approach is justified remains to be investigated.

Drainage, Postural↗