Introduction: Performance on cardiopulmonary exercise test (CPET) is influenced by genetic, racial and environmental factors. It is important to establish a set of reference values for the Filipino population. This study aimed to establish the maximum working capacity, peak oxygen uptake (VO2), peak carbon dioxide output (VCO2), tidal volume (TV) for normal Filipinos during exercise; determine the median perceived rate of exertion using the Borg Scale; and derive prediction equation models for maximum working capacity, peak VO2, peak VCO2 and maximum attained TV. Methods: The maximal cardiopulmonary responses were analyzed for 118 healthy sedentary adult Filipino subjects who underwent CPET using a symptom limited incremental progressive cycle ergometer driven protocol. A Vista MiniCPX Model 17670 was used. Models for predicting VO2 max, VCO2 peak, TV peak, and work max were derived with height, weight, age and sex being screened for significance as predictors. Linear and non-linear regression analyses were done. Results: The maximum working capacity for males was 154.21+26.6 watts and 93.02+15.57 watts for females while the peak VO2 for males was 4.90+3.11 and 4.56 2.41 liters/ minute for females. The predictive formulae derived from this study for maximum work capacity, peak VO2, VCO2 and tidal volume had acceptable correlation coefficients and performed as well as other published predictive equations based on Caucasian and Asian populations. Discussion: Differences between races as to performance in exercise testing was confirmed in this study so that it is worthwhile to utilize predictive equations specific for a certain racial population in the accurate interpretation of results. Performance in an exercise test also depends on the exercise protocol used so that the predictive equations in this study can be used only for exercise tests using a similar protocol. Conclusion Cardiopulmonary exercise testing was performed on a community based, healthy, sedentary Filipino population using a standard maximal incremental cycle ergometry protocol. Predictive equation models were derived for Maximum Working Capacity (r2=0.728), peak VO2 (r2= 0.123), peak VCO2 (r2=0.648), and TV (r2=0.579). The derived predictive formulae performed as well as other published predictive equations.
Exercise Test

BACKGROUND AND OBJECTIVE

Due to their academic load, medical students are highly susceptible to stress. Stress is one of the factors that can alter sleep quality which may consequently affect the cognitive performance of medical students. There has been a lack of published local literature that looks into the association between stress and sleep quality, especially during the COVID-19 pandemic. With this, the general objective of this study is to determine the effect of stress on the sleep quality of medical students from the University of the Philippines Manila - College of Medicine (UPCM).

METHODS

A cross-sectional study was conducted using a stratified random sample of 273 males and females of Learning Unit (LU) III (1st year) to VII (5th year) medical students from a college of medicine based in the Philippines, UPCM, during the second semester of the academic year 2021-2022. A self-administered questionnaire was distributed to assess sleep quality using the Pittsburgh Sleep Quality Index (PSQI), and stress level using the Kessler Psychological Distress Scale (K10). Kruskal-Wallis was used to test statistical differences between stress scores and the sleep quality of students from different year levels. Spearman's Rho was used to determine the correlation between stress and sleep, and a binary logistic regression was employed to study the association of stress with sleep while accounting for confounding variables namely caffeine intake, year level, daytime nap, duty hours, clinical rotation, sex, and age.

RESULTS

A high prevalence of stress (79.71%) and poor sleep quality (59.73%) among LU III to LU VII UPCM students were found, with a statistically positive correlation (⍴=0.44) 95CI [0.33-0.55] (p-value < 0.001). Both the stress scores and sleep quality indices were not statistically significantly different across LUs. Gathered data and interpreted results showed that medical students suffering from stress are more likely to have poor sleep quality, which can lead to low academic performance and high susceptibility to chronic diseases, compared to those medical students with low levels of stress. Only being an LU IV [OR=1.38 95CI (0.036-4.625)] and LU V [OR=2.13 95CI (0.296-6.936)] student had increased odds of having poor sleep quality compared to LU III students. Caffeine intake, daytime nap, duty hours, clinical rotation, sex, and age were not associated with poor sleep quality.

CONCLUSION

This study documents a statistically significant association between stress and poor sleep quality among LU III to LU VII UPCM students. A larger study covering multiple medical schools in the Philippines may be of merit for future investigations to generate nationwide data. Additional recommendations include: a) conducting a cross-sectional or a longitudinal study to detect changes in the characteristics of the population, b) observing the differences in the contributing factors at multiple points throughout the year, c) investigating the effect of dwelling set-up on sleep quality may also be investigated and d) determining if sleep quality affects the level of perceived stress of medical students.

Sleep Quality ; Students, Medical