**6. Positive effect on the human body**

Clothing covering the body of the user in the conditions of daily life affects their physiological parameters. The clothing made of bast fibers or made from blend bast fibers/synthetic fibers with high share of natural fibers provides the optimal comfort for users and affects some physiological parameters of the human body.

*Bast Fiber Textiles Addressed Improvement of Human Life DOI: http://dx.doi.org/10.5772/intechopen.105161*

#### **Figure 9.**

*Hygroscopicity of linen/PES fabrics tested in 65% and 100% relative humidity of air (based on [38]).*

#### **Figure 10.**

*Time needed to drop water sorption by tested linen/PES fabrics (based on [38]).*

#### **6.1 Muscle tension and fatigue tendency**

The human skin parameters that determine the comfort during clothing wearing in ambient climatic conditions and given level of physical activity are strongly related to well-being and can affect tendency to tiredness [38, 39].

The study on the monitoring of shoulder muscle tension of volunteers wearing linen/PES clothing with different shares of both components allowed identifying the phenomenon of clothing influence on electromyographic parameters of the muscles [38]. Examples of global electromyographic records taken at resting state from a volunteer wearing 100% linen clothing (a), 100% linen clothing double layers (b), 50% linen 50% PES clothing (c), and 100% PES are presented in **Figure 15**. The results of the tests proved that polyester clothing can change

#### **Figure 11.**

*Air permeability of linen/PES fabrics with different share of both types fiber (based on [38]).*

**Figure 12.**

*Surface resistance of linen/PES fabrics with different share of both types fiber (based on [38]).*

muscle electromyography (EMG) records in the range of amplitude and frequency after 5 hours of covering on the body with this kind of apparel, which indicates the occurrence of desynchronization of motor units. In the case of wearing linen clothing, such a phenomenon did not occur. The PES clothing gathered electrostatic charges on its surface causing increase in the mean value of frequency of motor units in the resting state. More intensive sweating of volunteers' body under the influence of PES clothing caused changes in the EMG amplitude in the resting state and amplitude and frequency during voluntary movement. The threshold value of polyester fiber share in blend with linen fiber is 25%. The clothing made of 100% linen fabric or 75% linen/25% PES did not cause the desynchronization of motor units in healthy muscles and provided optimal comfort of apparel use. Changes in the activity of the motor units of muscles found during the study proved that the

*Bast Fiber Textiles Addressed Improvement of Human Life DOI: http://dx.doi.org/10.5772/intechopen.105161*

#### **Figure 13.**

*The moisture of back skin under tested clothes during 5 hours of experiment (Grant 1000 series squirrel – Operating instruction) [38].*

#### **Figure 14.**

*The electrostatic potential on the surface of tested fabrics [39].*

polyester clothing can cause increase of tendency toward general fatigue of people wearing the clothing.

#### **6.2 Oxidative stress**

Study on clothing influence on some parameters of human physiology covered the experiment on oxidative stress affected by clothing made of different raw materials

#### **Figure 15.**

*Examples of global electromyographic records taken at resting state from a volunteer wearing: 100% linen clothing (a), 100% linen clothing double layers (b), 50% linen 50% PES clothing (c), and 100% PES (d) [39].*

[37]. The experiment was done with volunteers wearing linen and then PES clothing in given climatic conditions during an 8-hour rest period, 20-minute moderate physical activity at a level of 75 W, on a stationary bike and the period of returning to baseline. One of the ways to test the ability of the organism to defense itself against the reactive oxygen species is to determine the so-called total antioxidant status (TAS). This parameter informs about the total ability of tissues to neutralize exactly determined amount of reactive oxygen species. The TAS was tested based on blood analysis after each stage of the volunteers' activity.

The results of the TAS test are shown in **Figure 16**. The lower level of total antioxidative status in individuals wearing polyester clothing indicated that, probably, this is an effect of increased production of reactive oxygen species, which are responsible for the oxidative stress. The phenomena observed during conducted tests confirmed the stipulations that the wear made of linen—a natural fiber—not only guarantees a comfort, but may also have a positive effect on users' health. The clothes made from polyester fibers can have an unfavorable effect on human organism.

These TAS changes tested in conditions of increased sweating, i.e., during exercise, were statistically significant. The results of the research resulted from the following phenomena accompanying of polyester clothing:


### **6.3 UV barrier**

Garment barrier properties against ultraviolet radiation are mainly determined by the structure and thickness of fabric or knitted fabric used for clothing preparation. High fabric density and minimalized porosity play the most important role to block

*Bast Fiber Textiles Addressed Improvement of Human Life DOI: http://dx.doi.org/10.5772/intechopen.105161*

**Figure 16.** *The values of total antioxidant status (TAS) in volunteers wearing linen and PES clothing [40].*

UV rays transitioning through the fabric and make it impossible to touch the skin of the wearer.

Even in the dense structure of fabrics and proper thickness to make mechanical barrier against radiation, the clothing does not always ensure safety for wearers in conditions of intensive solar radiation.

Bast fibers contain in their chemical composition lignin and phenolic acids, including ferulic acid, with ability to absorb ultraviolet rays. The values of ultraviolet protection factor (UPF) of tested samples of linen fabrics characterized by different mesh/hollows content in their structure are shown in **Figure 17** [41]. Clothing made of bast fibers with proper parameters of fabric structure offers very good UV barrier properties—guarantee safety and optimal comfort for users under conditions of solar radiation.

In case of using the garment in extremely high UV index area, the inherent protective properties of bast fibers can be supported by the application of UV absorbers, for example, by nanolignin coating, which is the most ecological method of fabric modification [42, 43].
