oxygen uptake (VO2 peak (L/min)) values were 2.22 ± 0.32, 2.23 ± 0.29 and 1.97 ... (ml/kg.min) for G1, G2 and G3 were 31.6 ±5.9, 28.9 ±5.5 and 24.4 ±3.6 .... VT peak (L). 1.89. ± 0.26. 1.93. ± 0.30. 1.87. ± 0.29 fb peak (min). 48. ± 7. 48. ± 8. 46.
PEAK CARDIOPULMONARY EXERCISE DATA FOR HEALTHY SAUDI MALES. A. M. Al-Howaikan, B.Sc.; H. M. Al-Hazzaa, Ph.D., FACSM; A. F. Al-Mobaireek, MRCP; and S. A. Al-Majed, FRCP (C). Exercise Physiology Laboratory, Dept. of P. E. and Movement Sciences and Exercise Pulmonary Laboratory, Dept. of Medicine, King Saud University, Riyadh, Saudi Arabia.
ABSTRACT The use of cardiopulmonary exercise testing as a measure of functional capacity has increased substantially in recent years. Yet local normative data are remarkably lacking. Therefore, this study presents normal peak cardiopulmonary exercise values for 94 healthy Saudi males between the ages of 20 and 47 years. Graded exercise testing was performed using electronic cycle ergometer starting with 20 watts (W) and increasing work load (WL) by 10 W every minute until fatigue. Gas exchange parameters were continuously assessed using open circuit spirometry. Data were analyzed for three age groups: G1 (20-29 yr., n= 38), G2 (30-39 yr., n=36) and G3 (40-47 yr., n= 20). The findings indicated that absolute peak oxygen uptake (VO2 peak (L/min)) values were 2.22 ± 0.32, 2.23 ± 0.29 and 1.97 ±0.29 for G1, G2 and G3, respectively (G3 different from G1 and G2, p< 0.05). Respective values of VO2 peak relative to body mass (ml/kg.min) for G1, G2 and G3 were 31.6 ±5.9, 28.9 ±5.5 and 24.4 ±3.6 (G3 different from G1 and G2, p< 0.01). Maximal heart rate (HR max) dropped from 183 ± 8 bpm in G1 to 171±9 bpm in G3, with significant differences (p< 0.05) between the three groups. Maximal WL averaged 151.4 ±20.9 W for the whole group (ranged from 100 to 220 W). In addition, absolute VO2 peak had the highest correlation with exercise time (r = 0.81, p> 0.000), WL max (r = 0.78, p< 0.000), HR at WL 120 W (r = 0.67, p< 0.000), and thigh muscles strength (r = 0.40, p> 0.000). It was concluded that VO2 peak data presented in this study appear lower than those values reported for adult males of comparable age, weight and height in Western countries. Furthermore, these normal values of peak cardiopulmonary responses for healthy Saudi males would be very useful in interpreting maximal exercise data in Saudi patients suffering from cardiopulmonary impairments.
INTRODUCTION In recent years, cardiopulmonary exercise testing (CPXT) has become a common procedures in major hospitals and medical centers around the world.1-7 It objectively assesses the cardiac and respiratory responses of individuals to constant or graded exercise stress. 2,3 These responses can then be compared to previously established “normal” values, so inferences regarding limitation of exercise due to cardiac, respiratory, metabolic, endocrine, neuromuscular, or other factors may be made.1-9 Both treadmill and cycle ergometer are commonly used as a mode of CPXT, however cycle ergometer is widely utilized in clinical practice, because of its safety and accuracy in quantifying work load.2,3 Description of cardiopulmonary responses, of normal healthy subjects, to maximal exercise testing are widely published in many countries.2, 3, 6,10-12 However, despite its clinical importance, normal cardiopulmonary responses to maximal cycle ergometer in healthy Saudi adults are strikingly absent. Most available local studies reported data for active young males, 13,14 children and adolescents,15 or young athletes.16-18 Thus, it appears that there is a real need for normal cardiopulmonary exercise data, based on cycle ergometer testing of healthy untrained Saudi males.
PURPOSE OF THE STUDY To establish normal peak cardiopulmonary responses to maximal cycle ergometer testing in healthy untrained Saudi males, and to compare such values to those standards reported in the literature for normal adults elsewhere.
MATERIALS AND METHODS Subjects: Ninety-four healthy Saudi males, between the ages of 20 and 47 years, volunteered and gave informed consents to participate in this study. None of the subjects was physically active or engaged in any form of regular exercise. Prior to testing, each participant underwent a complete physical examination including 12-lead resting ECG and blood pressure measurements. Body fat content was estimated from skinfold measurements at four cites using Durnin and Womersley equation.19 In addition, grip and thigh muscle strength were assessed using isometric dynamometry.
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Cycle Ergometer Testing: Graded exercise testing was performed for each subject using a calibrated electronic cycle ergometer (Jaeger, Germany) in a comfortable laboratory environment. After collecting resting metabolic data, subject began the test with a two-minute warm-up period at a work load of 20 watts and a pedaling rate of 60 rpm. Work load was then raised by 10 watts every minute until the subject was no longer able to maintain the work rate. All subjects were encouraged to reach their maximal capacities.
Cardiopulmonary function assessments: Continuous gas exchange parameters were measured and reported every 30 seconds by an open circuit spirometry using ESO-Sprint (Jaeger, Germany). Gas analyzers were calibrated before each test by a known mixture of gases. In addition, heart rate was continuously monitored and recorded throughout the test using an ECG monitor and recorder (Hellige, Germany). Oxygen uptake was considered maximal when the respiratory exchange ratio reached a level higher than 1.0 and heart rate exceeded the 90% of the predicted maximal heart rate. Ventilatory anaerobic threshold (VAT) was also determined using the V-slope method.20 Maximal voluntary ventilation (MVV) was estimated by multiplying forced expiratory volume at one second (FEV1) by 35.
Statistical Analysis: Data were reported as means and standard deviations according to three age categories: G1 (20-29 yr.), G2 (30-39 yr.), G3 (40-47 yr.). ANOVA with Scheffe post hoc tests were performed to test the differences in anthropometric and physiologic variables among the three age groups. The level of significance was set at 0.05 or less. In addition, Pearson correlation was used to examine the relationships among selected anthropometric and cardiorespiratory variables for the whole sample. Multiple regression analysis with stepwise technique was also performed to predict peak oxygen uptake (VO2 peak) from body mass, height, age, and maximal work load.
RESULTS The results of the present study are presented in tables 1 through 4 and in figure 1. However, the major findings can be summarized as follow:
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1- Body fat content of the present sample increased with age. However, lean body mass remained almost the same across age. Body mass index (BMI) of this sample showed a trend that is similar to what was previously reported for adult Saudi males in the central region.21 2- Values of VO2 peak relative to body mass or relative to body surface area exhibited a significant reduction at G3 compared to G2. 3- Maximal heart rate showed a steady and significant decline throughout age groups. 4- O2 pulse index (O2 pulse/BSA) exhibited a significant reduction at G3 compared with G2. 5- Peak VO2 data for Saudi males reported in this study appear lower than the reported normal values for comparable healthy males in the USA, Canada, and seven European countries.10 Moreover, the measured VO2 peak of Saudi males in the present study seem to fall in the range of 72 to 79% of those predicted using Wasserman et al 2 prediction equation, based on age and body mass (figure 1). Reason for these low values in Saudi males could be attributed to the reduced level of physical activity in the general population,22 as well as to the decreased lean body mass, which is required to reach higher power output during cycle ergometer testing. 6- Absolute VO2 peak showed significantly moderate to high correlations with lean body mass, thigh muscle strength, maximal work load, heart rate at work load of 120 watts, and total exercise time. 7- Absolute VO2 peak can be predicted in Saudi males with high accuracy using body mass, age and maximal work load (table 4). 8- Maximal heart rate can also be predicted from age as follow: 194.83 (0.504 × age); R=0.411, R2 = 0.169, SEE = 8.4 bpm.
CONCLUSION VO2 peak values of Saudi males appear lower than those standards reported for adult males of comparable age, weight and height in Western countries. Furthermore, these normal values of peak cardiopulmonary responses to cycle ergometer for healthy Saudi males would be very useful when interpreting maximal exercise data in Saudi patients suffering from cardiopulmonary impairments. Acknowledgment: This research was partially supported by Research Center, College of Education, King Saud University.
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Table 1. Physical characteristics of the subjects (mean ± SD). AGE (years)
Variable Number of subjects Age (year) Body mass (kg) Height (cm) BMI (kg. m-2) Body fat (%) Lean body mass (kg)
Difference
20-29
30-39
40-47
38 24.8 ±3 72.4 ±14.9 171.9 ± 4.8 24.3 ± 4.9 19.4 ± 6.3 57.7 ± 8.6
36 33.5 ± 2.6 79.3 ±15.7 169.4 ± 4.6 27.2 ± 4.9 23.6 ±5 59.9 ± 8.9
20 43.3 ± 2.4 81.4 ±10 168.7 ±6 28.1 ±3 30.6 ± 3.8 56.5 ±5
1 ≠ 2 ≠ 3 ** 1≠3*
1≠2* 1≠3* 1 ≠ 2 ≠ 3 **
1= age group 20-29; 2= age group 30-39; 3= age group 40-47. p value= *
