**3. Results**

#### *3.1. Basic Characteristics*

The resting DBP, SBP, and BMI were within normal ranges. Other descriptive characteristics are presented in Table 1.


**Table 1.** Basic characteristics of the studied athletes.

Averaged data are presented as mean ± standard deviation (SD), and results of the *t*-test for dependent samples, \* *p* < 0.05, \*\* *p* < 0.01, \*\*\* *p* < 0.001 significantly different pre-training. BMI−body mass index; SBP−systolic blood pressure; DBP−diastolic blood pressure; rest−before cardiopulmonary exercise test; exerc−after cardiopulmonary exercise test; VO2max (mL/min/kg)−maximal oxygen uptake; HRpeak−pea<sup>k</sup> heart rate; LArest−resting lactate concentration; LAmax−maximal lactate concentration.

#### *3.2. Measured Parameters*

The values of the measured parameters are shown in Figure 3. At the first examination (before the training period), only Bmean significantly increased between the pre- (410.8) and post-exercise (449.3) measurements. At the second examination (after the training period), the values of all measured parameters significantly increased between resting and post-exercise condition. Bmean increased from 579.5 to 671.9, 16%; FImax increased from 685.8 to 742.4, 8% and FRmin from 459.1 to 520, 13%. All measured parameters (both resting and post-exercise) significantly increased between the first and second examination.

**Figure 3.** Measured parameters. Flow Mediated Skin Fluorescence parameters in athletes (N = 41) in two examinations, before and after the cardiopulmonary exercise test until exhaustion. Bmean—Changes in the mean value of the basal fluorescence; FImax—Changes in maximal fluorescence during ischemia; FRmin—Changes in the first minimal fluorescence value during reperfusion. Values are means (SD). A two-way analysis of variance (relation between exercise and training), post-hoc Scheffe test, significant differences between pre- and post-exercise: \*\*\* *p* < 0.001, \*\* *p* < 0.01, \* *p* < 0.05; significant differences between before and after training # *p* < 0.001, ‡ *p* < 0.01, § *p* < 0.05.

#### *3.3. Calculated Parameters*

The values of the calculated parameters are presented in Figure 4. Imax significantly decreased after exercise in both pre- (from 72.6 to 53.9, 26% decrease) and post-training (from 106.3 to 70.6, 34% decrease) examinations. Imax values were higher after than before training pre- (from 72.6 to 106.3, 46% increase) and post-exercise (from 53.9 to 70.6, 31% increase).

Rmin significantly increased after exercise compared to resting conditions in both examinations before (from 80.3 to 94.7, 18% increase) and after training (from 120.4 to 151.9, 26% increase). The pre- and post-exercise values of Rmin were higher after than before training (pre-exercise 50% and post-exercise 60%).

The IRampl parameter did not significantly differ between resting and post-exercise conditions in both examinations. Its pre- and post-exercise values were significantly higher after than before the training period (pre-exercise from 152.9 to 226.7, 48% increase; post-exercise from 148.6 to 222.4, 50% increase).

The values of CImax were significantly lower after than before exercise in both examinations (before training decreased from 0.5 to 0.4; after training decreased from 0.5 to 0.3). There were no differences observed before when compared to after training.

**Figure 4.** Calculated parameters. Flow Mediated Skin Fluorescence parameters in athletes (N = 41) in two examinations, before and after the cardiopulmonary exercise test. Imax—Changes in the net increase in fluorescence over the baseline during ischemia; IRampl—Changes in the amplitude of fluorescence change during ischemia and reperfusion; Rmin—Changes in the net reduction in fluorescence below the baseline; CImax – Changes in Imax/IRampl ratio. Values are means (SD). A two-way analysis of variance (relation between exercise and training), post-hoc Scheffe test, significant differences between pre- and post-exercise: \*\*\* *p* < 0.001, \*\* *p* < 0.01, \* *p* < 0.05; significant differences between before and after training # *p* < 0.001, ‡ *p* < 0.01, § *p* < 0.05.
