Medicine & Science in Sports & Exercise:
E-38 Free Communication/Poster - Vascular Function: JUNE 3, 2011 7:30 AM - 12:30 PM: ROOM: Hall B
1Laval University, Quebec, QC, Canada. 2Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada.
(No relationships reported)
Mental work has progressively replaced physical work and has become an important modality of human activity in the context of economic competitiveness and globalization. This situation is closely linked to the high prevalence of cardiovascular diseases, such as systemic hypertension, noted in industrialized societies.
PURPOSE: The aim of this study was to investigate the acute effect of mental effort on cardiovascular responses of young and healthy adults.
METHODS: Using a randomized 2-condition crossover design, the impact of a 45-min reading and writing session and a control resting condition of similar duration, on blood pressure (BP), heart rate (HR), and heart rate variability (HRV) responses, was evaluated in 35 healthy adults (22 males and 13 females; age: 24±3 years old and body mass index: 23±2 kg/m2; mean±SD). BP was measured at three specific times (-15, 20 and 40 min) during both experimental conditions and was then averaged. HRV was measured with a Holter during both conditions. Variables in the time and frequency domains were analyzed. HR was measured with the Holter and represents a mean of the 45-min period for each condition. Women were tested within 10 days following the start of their menses.
RESULTS: Diastolic BP (75±8 vs. 71±9 mm Hg; p < 0.05), HR (67±8 vs. 60±7 bpm; p < 0.05) as well as LF/HF ratio (2.8±1.4 vs. 1.9±1.1; p < 0.05) were higher during the mental work condition, while global HRV (SDNN: 88±27 vs.109±32 ms; p < 0.05) was lower when compared to the control condition. Moreover, cardiac parasympathetic activity indices were lower during the mental work versus the control condition (rMSSD: 52±19 vs. 67±21 ms, PNN50: 29±16 vs. 42±16 %, and HFln: 6.3±0.8 vs. 6.9±0.7 ms2; all p < 0.0001).
CONCLUSIONS: These results suggest that mental work acts as a stress factor, which increases blood pressure and heart rate through a decrease in cardiac parasympathetic modulation in healthy young adults. This study highlights the importance of considering mental work in the global study of systemic hypertension. While we now understand the acute influence of mental work on hemodynamics, its long-term cardiovascular impact remains to be elucidated and we speculate that it could play a role in the increased prevalence of systemic hypertension in our society.