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Fulltext Haematological and plasma electrolyte changes after long distance running in high heat and humidity

Singh R, Sirisinghe RG

Singapore Med J, 1999 Feb;40(2):84-7.
PMID: 10414164

To investigate the acute effects of an 18 km run on the haematological and plasma electrolyte parameters, in recreational runners under conditions of high temperatures and humidity.
Rehydration with sodium-enriched coconut water after exercise-induced dehydration

Ismail I, Singh R, Sirisinghe RG

Southeast Asian J. Trop. Med. Public Health, 2007 Jul;38(4):769-85.
PMID: 17883020

This crossover study assessed the effectiveness of plain water (PW), sports drink (SD), fresh young coconut water (CW) and sodium-enriched fresh young coconut water (SCW) on whole body rehydration (R) and plasma volume (PV) restoration after exercise-induced dehydration. Ten healthy male subjects ran at 65% of VO2max in an environmental temperature of 32.06 +/- 0.02 degree C with a relative humidity (rh) of 53.32 +/- 0.17% for 90 minutes to lose 3% body weight (BW). During the 2-hour rehydration period, subjects drank, in randomized order, PW, SD, CW or SCW equivalent to 120% of BW lost in three boluses representing 50, 40 and 30% of the fluid lost at 0, 30, and 60 minutes, respectively. In all trials subjects were still somewhat dehydrated even after the 2-hour rehydration period. Indexes of percent rehydration with PW, SD, CW and SCW were 58 +/- 2, 68 +/- 2, 65+/- 2 and 69 +/- 1%, respectively, with significantly better rehydration with SD and SCW. The rehydration indexes for SD and SCW were significantly lower than PW (p < 0.01). PV was restored to euhydration levels after 2 hours of rehydration with SD, CW and SCW but not with PW. The plasma glucose concentration were significantly higher when SD, CW and SCW were ingested. SCW was similar in sweetness to CW and SD but caused less nausea and stomach upset compared to SD and PW. In conclusion, ingesting SCW was as good as ingesting a commercial sports drink for whole body rehydration after exercise-induced dehydration but with better fluid tolerance.
Decay of heat acclimation during exercise in cold and exposure to cold environment

Saat M, Sirisinghe RG, Singh R, Tochihara Y

Eur J Appl Physiol, 2005 Oct;95(4):313-20.
PMID: 16151840

Sixteen male students exercised for 14 days (1 h/day) in the heat for heat acclimation (HA). During deacclimation (DA) one group exercised in the cold (EXG, n=8) for 60 min/day (morning) and was exposed to the cold for another hour (afternoon) for 14 days. The other group was exposed to the cold (EPG, n=8) for 1 h each in the morning and afternoon (Ta: 18.0 degrees C, RH: 58%) over the same period. All returned to exercise in the heat for reacclimation (RA) for 10 days. Subjects were tested on days 1, 16, 21, 32, 36 and 44 on a bicycle ergometer for 60 min at 60% of VO(2max) in the heat (Ta: 31.1 degrees C, RH: 70%). Rectal temperature (T (re)) and heart rate (HR) at 40 min of exercise were used to determine the decay/gain of HA, which was calculated using the formula described by Pandolf et al. (Ergonomics, 20:399-408, 1977). After HA (day 16) T (re) and HR decreased significantly. During DA, EXG showed decay in T (re) of 24 and 35% and HR of 29 and 35% on days 21 and 32, respectively. For EPG the corresponding decay was of 2 and 9% for T (re) and 17 and 17% for HR. After 10 days of RA, EXG showed gains of 11% in T (re) and 12% in HR, while EPG showed gains of 47% in T (re) and 38% in HR. In conclusion, EXG had greater decay during DA and lower gains in RA compared to EPG. However, the differences between groups were significant only for T (re) after 4 days of DA.
Fulltext Spirometric studies in Malaysians between 13 and 69 years of age

Singh R, Singh HJ, Sirisinghe RG

Med J Malaysia, 1993 Jun;48(2):175-84.
PMID: 8350793

Spirometry was performed on 1,999 subjects (1,385 males and 614 females) ranging in age from 13 to 69 years and comprising of all the main races in Malaysia. They were divided into 6 age groups. Mean forced vital capacity (FVC) in the males and females was 3.49 +/- 0.02 L and 2.51 +/- 0.02 L respectively. Both FVC and FEV1 correlated negatively with age. Regression analysis on data between the ages of 20 to 69 years revealed an age-related decline in FVC of about 30 ml per year of life in the males and 22 ml per year in the females. Multiple stepwise regression of the data for the prediction of an individual's FVC above the age of 20 years gave an equation for the males: FVC = 0.0407 (height)-0.0296 (age)-2.343 L and for the females: FVC = 0.031 (height)-0.022 (age)-1.64 L. Predicted FVC values derived from equations based on other populations were considerably higher than the observed mean in this study, re-emphasizing the need to be cautious when applying formulae derived from one population to another. Grossly erroneous conclusions may be reached unless predicted equations for lung-function tests for a given population group are derived from studies based upon the same population group.
Physical and physiological profiles of Malaysian dragon boat rowers

Singh R, Singh HJ, Sirisinghe RG

Br J Sports Med, 1995 Mar;29(1):13-5.
PMID: 7788209

Maximal oxygen consumption (VO2max) and maximal workload attained (WLmax) were determined in 28 Malaysian dragon boat rowers who were exercised to exhaustion on an arm ergometer. Mean VO2max was 2.75 l min-1 at a mean WLmax of 195.5 W. Anaerobic endurance power of the arms, determined by cranking at 100 RPM at a workload of 400 W and the time taken to maintain the cadence until it fell to 75 RPM, was 34.9(+/- 2.3) s. Leg performance, as determined by standing long jump and vertical jump, was 140.0(+/- 4.5) kg m and 100.3(+/- 3.1) kg m s-1 respectively. Right hand grip strength was significantly (p < 0.001) greater than the left hand. Percentage body fat of the rowers was 11.8(+/- 0.6)%. These values represent the first measurements of their kind performed on dragon boat rowers in Malaysia.
Fulltext Spirometric volumes in Malaysian males

Singh R, Singh HJ, Sirisinghe RG

Southeast Asian J. Trop. Med. Public Health, 1994 Jun;25(2):341-8.
PMID: 7855654

Spirometry was performed on 1,485 male subjects ranging in age from 13 years to 78 years and comprising of all the main ethnic groups in Malaysia. They were divided into six age categories. Mean forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) were 3.45 +/- 0.02 and 3.10 +/- 0.02, respectively. Both FVC and FEV1 correlated negatively with age. Regression analysis revealed an age-related decline in FVC of 295 ml per decade of life. Multiple stepwise regression of the data for the prediction of an individual's FVC above the age of 20 years gave the equation FVC (1) = 0.0404 (height in cm)-0.0295 (age in years)-2.2892. Predicted FVC values derived from equations based on other populations were considerably higher than the observed mean in this study. This study therefore, reemphasises the need to be cautions when applying formulae derived from one population to another. Grossly erroneous conclusions may be reached unless predicted equations for lung-function tests for a given population group are derived from studies based upon the same population group.
Cardiopulmonary fitness in a sample of Malaysian population

Singh R, Singh HJ, Sirisinghe RG

Jpn. J. Physiol., 1989;39(4):475-85.
PMID: 2601189

Lung capacity and maximum oxygen uptake (VO2max) were measured directly in 167 healthy males, from all the main races in Malaysia. Their ages ranged from 13 to 59 years. They were divided into five age groups (A to E), ranging from the second to the sixth decade. Lung capacities were determined using a dry spirometer and VO2max was taken as the maximum rate of oxygen consumption during exhaustive exercise on a cycle ergometer. Mean forced vital capacity (FVC) was 3.3 +/- 0.5 l and it correlated negatively with age. Mean VO2max was 3.2 +/- 0.2 l.min-1 (56.8 +/- 3.5 ml.kg-1.min-1) in Group A (13-19 years) compared to 1.7 +/- 0.2 l.min-1 (28.9 +/- 2.9 ml.kg-1.min-1) in Group E (50-59 years). Regression analysis revealed an age-related decline in VO2max of 0.77 ml.kg-1.min-1.year-1. Multiple regression of the data gave the following equations for the prediction of an individual's VO2max: VO2max (l.min-1) = 1.99 + 0.035 (weight)-0.04 (age), VO2max (ml.kg-1.min-1) = 67.7-0.77 (age), where age is in years, weight in kg. In terms of VO2max as an index of cardiopulmonary performance. Malaysians have a relatively lower capacity when related to the Swedish norms or even to those of some Chilean workers. Malaysians were, however, within the average norms of the American Heart Association's recommendations. Age-related decline in VO2max was also somewhat higher in the Malaysians.
Forced vital capacity in Malaysian females

Singh R, Singh HJ, Sirisinghe RG

Jpn. J. Physiol., 1992;42(3):407-14.
PMID: 1434102

Spirometry was performed on 614 female subjects ranging in age from 13 to 69 years and comprising all the main races in Malaysia. They were divided into six age categories. Mean forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were 2.51 +/- 0.02 and 2.31 +/- 0.02l, respectively. Both FVC and FEV1 correlated negatively with age. Regression analysis revealed an age-related decline in FVC of 220 ml per decade of life. Multiple stepwise regression of the data for the prediction of an individual's FVC above the age of 20 years gave an equation: FVC(l) = 0.0312 (height)-0.022 (age)-1.64. Predicted FVC values derived from equations based on other populations were considerably higher than the observed mean in this study. Our study, therefore, reemphasizes the need to be cautious when applying formulae derived from one population to another. Grossly erroneous conclusions may be reached unless predicted equations for lung-function tests for a given population group are derived from studies based on the same population group.
Fulltext The variability of blood pressure following repeated measurements

Singh HJ, Singh R, Sirisinghe RG, Upadaya S

Med J Malaysia, 1991 Dec;46(4):356-62.
PMID: 1840445

Two series of Blood Pressure (BP) measurements were carried out to assess the variability in BP following repeated measurements in normotensive individuals. In one series, measurement of BP on three occasions three and seven days apart revealed a significant drop in BP in unaccustomed subjects ('untrained'). In a second series assessing the significance of time-interval between measurements or the number of measurements, it was found that a significant fall in BP occurred over the first four days in 'untrained' individuals, whose blood pressure was measured repeatedly for five consecutive days. A significant positive correlation was evident between the falls in systolic and diastolic pressures and the pressure at first screening. Assessment of the anxiety status revealed a significantly lower state anxiety in 'trained' subjects. It therefore appears that (a) BP in normotensive individuals previously unaccustomed to BP measurements, drops significantly with repeated measurements, (b) the number of measurements seem more important than the time-interval between measurements, (c) the largest falls occur in individuals with high initial pressures and (d) the fall upon repeated measurements may be due to reduced anxiety as familiarity with the procedure makes the subjects comparatively relaxed and less state anxious.
Fulltext Cardiopulmonary capacities of Malaysian females

Singh R, Singh HJ, Sirisinghe RG

Singapore Med J, 1995 Apr;36(2):169-72.
PMID: 7676261

Aerobic capacity (VO2max) and lung capacities were measured in 66 healthy females ranging in age from 13 to 49 years. Forced vital capacity (FVC) and peak expiratory flow rate (PEFR) were measured using a dry spirometer and Wrights peak flow meter respectively. Cardiopulmonary parameters were obtained from a progressive ergocycle test to exhaustion. Mean FVC and PEFR obtained were 2.73 +/- 0.07 L and 412 +/- 8.5 L/min respectively. FVC correlated negatively with age in subjects from the 3rd to 5th decade of age (r = 0.38, p < 0.05). Mean VO2max was 43.2 +/- 0.9 ml/kg/min in the 2nd decade compared to 30.3 +/- 0.7 ml/kg/min in the fifth decade. Regression analysis revealed an age related decline in VO2max of 0.45 +/- 0.8 ml/kg/min/year, which was found to be somewhat higher compared to other studies.
Effects of short-term exercise in the heat on thermoregulation, blood parameters, sweat secretion and sweat composition of tropic-dwelling subjects

Saat M, Sirisinghe RG, Singh R, Tochihara Y

J Physiol Anthropol Appl Human Sci, 2005 Sep;24(5):541-9.
PMID: 16237263

This study investigates the effects of a short-term aerobic training program in a hot environment on thermoregulation, blood parameters, sweat secretion and composition in tropic-dwellers who have been exposed to passive heat. Sixteen healthy Malaysian-Malay male volunteers underwent heat acclimation (HA) by exercising on a bicycle ergometer at 60% of VO2max for 60 min each day in a hot environment (Ta: 31.1+/-0.1 degrees C, rh: 70.0+/-4.4%) for 14 days. All parameters mentioned above were recorded on Day 1 and at the end of HA (Day 16). On these two days, subjects rested for 10 min, then cycled at 60% of VO2max for 60 min and rested again for 20 min (recovery) in an improvised heat chamber. Rectal temperature (Tre), mean skin temperature (Tsk) heart rate (HR), ratings of perceived exertion (RPE), thermal sensation (TS), local sweat rate and percent dehydration were recorded during the test. Sweat concentration was analysed for sodium [Na+]sweat and potassium. Blood samples were analysed for biochemical changes, electrolytes and hematologic indices. Urine samples were collected before and after each test and analysed for electrolytes.After the period of acclimation the percent dehydration during exercise significantly increased from 1.77+/-0.09% (Day 1) to 2.14+/-0.07% (Day 16). Resting levels of hemoglobin, hematocrit and red blood cells decreased significantly while [Na+]sweat increased significantly. For Tre and Tsk there were no differences at rest. Tre, HR, RPE, TS, plasma lactate concentration, hemoglobin and hematocrit at the 40th min of exercise were significantly lower after the period of acclimation but mean corpuscular hemoglobin and serum osmolality were significantly higher while no difference was seen in [Na+]sweat and Tsk. It can be concluded that tropic-dwelling subjects, although exposed to prolonged passive heat exposure, were not fully heat acclimatized. To achieve further HA, they should gradually expose themselves to exercise-heat stress in a hot environment.
Rehydration after exercise with fresh young coconut water, carbohydrate-electrolyte beverage and plain water

Saat M, Singh R, Sirisinghe RG, Nawawi M

J Physiol Anthropol Appl Human Sci, 2002 Mar;21(2):93-104.
PMID: 12056182

This is to cross-over study to assess the effectiveness of fresh young coconut water (CW), and carbohydrate-electrolyte beverage (CEB) compared with plain water (PW) for whole body rehydration and blood volume (BV) restoration during a 2 h rehydration period following exercise-induced dehydration. Eight healthy male volunteers (mean age and VO2max of 22.4 +/- 3.3 years and 45.8 +/- 1.5 ml min kg-1 respectively) exercised at 60% of VO2max in the heat (31.1 +/- 0.03 degrees C, 51.4 +/- 0.1% rh) until 2.78 +/- 0.06% (1.6 +/- 0.1 kg) of their body weight (BW) was lost. After exercise, the subjects sat for 2 h in a thermoneutral environment (22.5 +/- 0.1 degrees C; 67.0 +/- 1.0% rh) and drank a volume of PW, CW and CEB on different occasions representing 120% of the fluid loss. A blood and urine sample, and the body weight of each subject was taken before and after exercise and at 30 min intervals throughout a rehydration period. Each subject remained fasted throughout rehydration. Each fluid was consumed in three portions in separate trials representing 50% (781 +/- 47 ml), 40% (625 +/- 33 ml) and 30% (469 +/- 28 ml) of the 120% fluid loss at 0, 30 and 60 min of the 2 h rehydration period, respectively. The drinks given were randomised. In all the trials the subjects were somewhat hypohydrated (range 0.08-0.18 kg BW below euhydrated BW; p > 0.05) after a 2 h rehydration period since additional water and BW were lost as a result of urine formation, respiration, sweat and metabolism. The percent of body weight loss that was regained (used as index of percent rehydration) during CW, PW, and CEB trials was 75 +/- 5%, 73 +/- 5% and 80 +/- 4% respectively, but was not statistically different between trials. The rehydration index, which provided an indication of how much of what was actually ingested was used for body weight restoration, was again not different statistically between trials (1.56 +/- 0.14, 1.36 +/- 0.13 and 1.71 +/- 0.21 for CW, CEB and PW respectively). Although BV restoration was better with CW, it was not statistically different from CEB and PW. Cumulative urine output was similar in all trials. There were no difference at any time in serum Na+ and Cl-, serum osmolality, and net fluid balance between the three trials. Urine osmolality decreased after 1 h during the rehydration period and it was lowest in the PW trial. Plasma glucose concentrations were significantly higher compared with PW ingestion when CW and CEB were ingested during the rehydration period. CW was significantly sweeter, caused less nausea, fullness and no stomach upset and was also easier to consume in a larger amount compared with CEB and PW ingestion. In conclusion, ingestion of fresh young coconut water, a natural refreshing beverage, could be used for whole body rehydration after exercise.
Effects of exercise in the heat on thermoregulation of Japanese and Malaysian males

Saat M, Tochihara Y, Hashiguchi N, Sirisinghe RG, Fujita M, Chou CM

J Physiol Anthropol Appl Human Sci, 2005 Jul;24(4):267-75.
PMID: 16079566

The effect of low-intensity exercise in the heat on thermoregulation and certain biochemical changes in temperate and tropical subjects under poorly and well-hydrated states was examined. Two VO2max matched groups of subjects consisting of 8 Japanese (JS) and 8 Malaysians (MS) participated in this study under two conditions: poorly-hydrated (no water was given) and well-hydrated (3 mL x Kg(-1) body weight of water was provided at onset of exercise, and the 15th, 35th and 55th min of exercise). The experimental room in both countries was adjusted to a constant level (Ta: 31.6+/-0.03 degrees C, rh: 72.3+/-0.13%). Subjects spent an initial 10 min rest, 60 min of cycling at 40% VO2max and then 40 min recovery in the experimental room. Rectal temperatures (Tre) skin temperatures (Tsk), heart rate (HR), heat-activated sweat glands density (HASG), local sweat rate (M sw-back) and percent dehydration were recorded during the test. Blood samples were analysed for plasma glucose and lactate levels.The extent of dehydration was significantly higher in the combined groups of JS (1.43+/-0.08%) compared to MS (1.15+/-0.05%). During exercise M sw-back was significantly higher in JS compared to MS in the well-hydrated condition. The HASG was significantly more in JS compared to MS at rest and recovery. Tre was higher in MS during the test. Tsk was significantly higher starting at the 5th min of exercise until the end of the recovery period in MS compared to JS. In conclusion, tropical natives have lower M sw-back associated with higher Tsk and Tre during the rest, exercise and recovery periods. However, temperate natives have higher M sw-back and lower Tsk and Tre during experiments in a hot environment. This phenomenon occurs in both poorly-hydrated and well-hydrated states with low intensity exercise. The differences in M sw-back, Tsk and Tre are probably due to a setting of the core temperature at a higher level and enhancement of dry heat loss, which occurred during passive heat exposure.
Fulltext Study protocol: Effectiveness of patient centered pharmacist care in improving medication adherence, clinical parameters and quality of life among hemodialysis patients

Paneerselvam GS, Aftab RA, Sirisinghe RG, Lai PSM, Lim SK

PLoS One, 2022;17(2):e0263412.
PMID: 35180236 DOI: 10.1371/journal.pone.0263412

BACKGROUND: Patients requiring hemodialysis (HD) often have several chronic comorbidities, which necessitate the use of several medications and hence put them at high risk of polypharmacy. Medication-related problems (MRPs) among HD patients are a serious issue as they can increase morbidity and nonadherence with medications. To overcome this issue, a unique pharmacy practice model including medication review (MR) and motivational interviewing (MI) is needed to improve medication adherence, by reducing MRPs and optimizing therapeutic outcomes. The present study aims to assess the effectiveness of MR and MI in improving medication adherence, quality of life (QOL) and clinical outcomes among end-stage renal disease (ESRD) patients who are on dialysis.
METHOD AND DESIGN: This pre-post study will be conducted prospectively among patients with ESRD who have been on dialysis at the Hemodialysis Unit, Hospital Kuala Lumpur and the Hemodialysis Affiliated Centers of the University Malaya Medical Centre, from August 2020 till August 2021. Medication adherence will be assessed using the General Medication Adherence Scale (GMAS), whilst patients' HRQOL will be assessed using the Kidney Disease Quality of Life Short Form 36 (KDQOL-36). Clinical parameters such as blood glucose level, calcium, phosphate, hemoglobin and serum low-density lipoprotein (LDL) levels will be obtained from medical records. A total of 70 patients will be recruited.
DISCUSSION: We hypothesize that the implementation of pharmacy-based MR and MI may expect an increase in medication adherence scores and increase in HRQOL scores from baseline as well as achieving the clinical lab parameters within the desired range. This would indicate a need for a pharmacist to be involved in the multidisciplinary team to achieve a positive impact on medication adherence among hemodialysis patients.
TRIAL REGISTRATION: Ethical approval has been obtained from the National Medical Research and Ethics Committee NMRR: 20-1135-54435 and Medical Research Ethics Committee, University Malaya Medical Centre MREC ID NO: 202127-9811.

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