**3. Results**

#### *3.1. Somatometric Characteristics*

The somatometric characteristics of the participants in each group (i.e., BCa patients and healthy controls) are shown in Table 1. Height was 1.61 ± 0.05 m and 1.65 ± 0.04 m in the BCa and control group, respectively, while body mass was 69.49 ± 12.67 kg in BCa patients and 69.04 ± 5.25 kg in healthy controls. BMI was used for the classification of participants as underweight, normoweight, overweight or obese. These results reveal that BCa patients' BMI was 26.63 ± 5.27 kg/m2, categorizing them as overweight, by contrast with the healthy females in the control group whose BMI was marginally normal (25.30 ± 3.95 kg/m2).

**Table 1.** Somatometric characteristics of breast cancer patients and healthy participants (control group).


Data are presented as mean ± SD. No statistically significant differences were found between groups (p>0.05).

#### *3.2. Quality of Life*

#### 3.2.1. Control Group

Healthy females who served as the control group self-evaluated their QoL using the SF-36 Health Survey Version 3.0. Regarding their general QoL, the participants scored 70.14 ± 19.49, while for their physical, emotional, social and role functioning their score was 84.46 ± 15.48, 59.33 ± 17.83, 61.79 ± 27.05 and 79.17 ± 29.76, respectively (Figure 1). Moreover, in the symptom scales, pain was scored with 70.42 ± 22.93 and fatigue with 58.06 ± 12.23. Positive correlations were revealed between physical functioning and pain (r = 0.4432, p = 0.007), fatigue (r = 0.4847, p = 0.003), emotional functioning (r = 0.4133, p = 0.012) and role functioning (r = 0.3869, p = 0.020). Positive correlations were also found between QoL and the scales of physical functioning (r = 0.4072, p = 0.014) and fatigue (r = 0.6653, p = 0.00001), (Figure 2).

#### 3.2.2. Breast Cancer Group

Similarly to the control group, the women of the BCa group self-estimated their QoL using the EORTC-QLQ-C30 Questionnaire. Women in the BCa group scored their physical functioning significantly lower compared with the healthy controls (71.48 ± 23.35 vs 84.46 ± 15.48; p<0.01). However, their overall QoL, as well as their emotional, social and role functioning score, was 63.43 ± 20.63, 67.13 ± 27.02, 68.52 ± 31.31 and 68.98 ± 26.77, respectively, revealing no significant di fferences with the control group (p > 0.05) (Figure 1). It is noted that comparisons between the BCa and control group were performed only between the above-mentioned scales, since the rest of them in each questionnaire have a di fferent way of scoring.

As far the symptomatology is concerned, fatigue was scored at 42.28 ± 20.54, dyspnea at 25.93 ± 28.85 and pain at 19.44 ± 24.40. A negative correlation was found between QoL and fatigue (r = −0.7410, p = 0.00001), as well as between physical functioning and pain (r = −0.6149, p = 0.0001), fatigue (r = −0.6661, p = 0.0001) and dyspnea (r = −0.3320, p = 0.0493), (Figure 2). In contrast, a positive correlation was revealed between physical functioning and QoL (r = 0.4914, p = 0.0024), social functioning (r = 0.5954, p = 0.0001) and emotional functioning (r = 0.3663, p = 0.0263) (Figure 2).

**Figure 1.** Self-estimation of the overall quality of life (QoL) and its functional parameters in women undergoing chemotherapy for breast cancer compared with healthy controls. Data are presented as mean ± SD. \*\*: Significantly different at p < 0.01.

**Figure 2.** Correlational analyses revealed significant associations, among others (see text for details), between fatigue and quality of life (**<sup>a</sup>**,**<sup>c</sup>**), as well as between physical functioning and quality of life (**b**,**d**), both in the breast cancer and the control group.

#### *3.3. Exercise Behavior*

Exercise behavior was self-reported by all participants using the International Physical Activity Questionnaire (IPAQ) (Figure 3). Specifically, BCa patients exhibited a total energy expenditure of 2267 ± 1965 MET-min/week, while healthy controls spent 2630 ± 2840 MET-min/week, showing no significant di fferences between groups (p > 0.05). In particular, no significant di fferences (p > 0.05) were found between the two groups in the time spent walking (BCa group: 782 ± 1,153 MET-min/week vs Control group: 721 ± 950 MET-min/week). A similar (p > 0.05) energy expenditure was also spent in moderate PAs by both BCa and control group, i.e., 1460 ± 1549 vs 1089 ± 1724 MET-min/week, respectively. Interestingly, on the other hand, BCa patients were found to participate in vigorous PAs disproportionally less than the control group, expending only 134 ± 469 MET-min/week, as opposed to the control group that spent 985 ± 1,508 MET-min/week in high-intensity activities (p < 0.001). It is noted that moderate PAs require intermediate physical e ffort and make breathing somewhat harder than normal, while vigorous PAs need excess physical e ffort, increasing breath rate.

**Figure 3.** Self-reported physical activity levels (International Physical Activity Questionnaire (IPAQ)) in women undergoing chemotherapy for breast cancer compared with healthy controls, expressed in MET-min per week. Data are presented as mean ± SD.\*\*\*: Significantly di fferent at p<0.001.

Furthermore, BCa patients were found to spend more time sitting during the day (4.20 ± 2.76 h/day) in comparison with the control group (3.16 ± 1.25 h/day), (p < 0.05). Again, it is noted that sedentary time includes time spent sitting or lying down during work and leisure, or at home and excludes sleeping hours.

#### *3.4. Associations between Exercise Behavior and Quality of Life*

In the BCa group, a positive correlation was demonstrated between physical functioning and total energy expenditure (r = 0.4069, p = 0.0316) (Figure 4a), as well as between QoL and participation in vigorous PAs (r = 0.3985, p = 0.0357). Similarly, a positive correlation was also found in the control group between the engagemen<sup>t</sup> in vigorous PAs and QoL (r = 0.4993, p = 0.0094) (Figure 4b), as well as between vigorous PAs and physical functioning (r = 0.5149, p = 0.0071).

**Figure 4.** Correlational analyses showed significant associations, among others (see text for details), between (**a**) total energy expenditure and physical functioning in the breast cancer group as well as between (**b**) the engagemen<sup>t</sup> in vigorous PAs and the quality of life, in the control group.
