Cardiorespiratory, enzymatic and hormonal responses during and after walking while fasting

The aim of the present study was to observe whether performing a low intensity endurance exercise following an overnight fasted (FAST) or fed (FED) condition promotes different cardiorespiratory, enzymatic and hormonal responses. Nine male physical active subjects, (age 21.89 +/- 2.52 years old, height 175.89 +/- 5.16 cm, weight 72.10 +/- 4.31 kg, estimated body fat 7.25 +/- 2.11%), randomly performed two sessions of 45 minutes' low intensity exercise (individual ventilator threshold) interspersed by seven days, differentiated only in whether they were provided with a standardized meal or not. The oxygen consumption (VO2) and heart rate (HR) were measured continuously at the 30-min rest, the 45-min during and the 30-min post-exercise. The testosterone (T) and cortisol (C) hormones were measured at rest, immediately post-exercise and 15-min post-exercise. The Glucose (GLU), Free fatty acids (FFA) and enzyme lipase activity (ELP) were measured at rest, 15-min and 30-min exercise, immediately, 15-min and 30-min post-exercise. Significantly lower values were observed in FED compared to FAST with: C (nmol/L) from pre (428.87 +/- 120.41; 454.62 +/- 148.33, respectively) to immediately post-exercise (285.10 +/- 85.86; 465.66 +/- 137.70, respectively) and 15-min post-exercise (248.00 +/- 87.88; 454.31 +/- 112.72, respectively) (p<0.05); and GLU at all times, with an exception at 15-min post-exercise. The testosterone/cortisol ratio (T/C) was significantly higher in the FED compared with FAST from pre (0.05 +/- 0.02, 0.05 +/- 0.01, respectively) to 15-min post-exercise (0.08 +/- 0.03, 0.05 +/- 0.02, respectively). No other significant differences were observed between conditions. We conclude that fasting prior to low intensity endurance exercise does not seem be advantageous, when it comes to fat loss, compared with the same exercise performed after a meal.