2.1.5. Statistical Analysis

The Kolmogorov–Smirnov test with mean values was used to test the normality of distribution. The mean (μ) and standard deviation (DT) of the anthropometric measurement variables (body mass and BMI), HR variables (walking HR and HR at the end of the test), UKK test measurements (total time and fitness index), and VO2max of the participants were determined. In addition, test reliability was determined by calculating the coefficient of variation of VO2max between pretest and posttest in the RW and NW groups.

A mixed-design ANOVA for participants was used between groups (control, Nordic walking, and recreational walking) and moment intervention (pretest–posttest). To establish the differences in outcomes, we used a one-way analysis of variance (ANOVA) in the preand posttest. Pairwise comparisons were performed with Bonferroni's adjustment. Effect size is indicated with partial eta squared (η2) for Fs [40]. The Greenhouse–Geisser correction was applied when sphericity was violated [41]. In such a case, corrected probability values were reported. Differences in participant groups were found in the five categories of UKK fitness index. Regarding the pretest and posttest differences among all groups, a repeated-measures ANOVA test was used for two dependent samples. This process was carried out with regard to anthropometric measurement variables, HR variables, UKK test measurements, and VO2max in all groups.

All statistical analyses were performed using the Statistical Package for Social Science (IBM SPSS Statistics for Windows 21.0. Armonk, NY, USA).

#### **3. Results**

*3.1. Comparison of the Participant Groups (Control, RW, and NW) Relative to Anthropometric Measurement Variables, HR Variables, UKK Test Measurements, and VO2max*

Table 2 shows only one significant difference among the three participant groups in the pretest. The walking HR was lower in the RW group than that in the control and NW groups (79.17 ± 9.45 bt/min vs. 82.13 ± 9.36 bt/min and 87.12 ± 12.36 bt/min, respectively, *p* < 0.001).

**Table 2.** ANOVA for anthropometric measurement variables, heart rate, UKK walking test time and fitness index, and VO2max for pretest, with mean values (SD).


Note. UKK: Urho Kaleva Kekkonen; BMI: body mass index; VO2max: maximal oxygen consumption; m: metre, kg: kilogram; bt: beat; min: minute; mL: millilitre; η2: effect size by eta square; SD: standard deviation; df: degrees of freedom (2, 163 for pretest); a,b superscripts with the same letter show a degree of significant difference between both groups (*p* < 0.05). Pairwise comparisons were performed with Bonferroni's adjustment.

However, Table 3 reveals several significant differences among the control, NW, and RW groups, such as the walking HR (82.35 ± 9.09 bt/min vs. 79.45 ± 9.36 bt/min and 73.54 ± 7.32 bt/min, respectively, *p* < 0.001) and HR at the end of the test (114.13 ± 11.56 bt/min vs. 105.09 ± 11.61 bt/min and 106.51 ± 14.81 bt/min, respectively, *p* < 0.001). The results of measurements of the UKK test in terms of the UKK total time spent to walk two kilometres and the fitness index were significantly worse in the control group than those for the NW and RW groups, as detailed below. Participants in the RW group spent the shortest time to walk two kilometres (RW group = 22.06 ± 1.91 min; NW group = 22.11 ± 1.76 min; control group = 23.32 ± 1.84 min; *p* < 0.001) and obtained the best UKK fitness index (RW group = 88.92 ± 19.42; NW group = 84.72 ± 15.94; control group = 72.95 ± 18.13; *p* < 0.001). Finally, the RW group showed higher VO2max than the NW and control groups (24.51 ± 6.41 mL·min−1·kg−<sup>1</sup> vs. 23.58 ± 6.05 mL·min−1·kg−<sup>1</sup> and 19.59 ± 6.14 mL·min−1·kg<sup>−</sup>1, respectively, *p* < 0.001). According to the coefficient of variation of VO2max, it is possible to observe an increase of 23.59% in the difference between pretest and posttest results in RW and 30.20% in NW.

**Table 3.** ANOVA posttest results in terms of anthropometric measurement variables, heart rate, UKK walking test time and fitness index, and VO2max, with mean values (SD).


Note. UKK: Urho Kaleva Kekkonen; BMI: body mass index; VO2max: maximal oxygen consumption; m: metre, kg: kilogram; bt: beat; min: minute; mL: millilitre; η2: Effect size by eta square; SD: standard deviation; df: degrees of freedom (2, 163 for posttest intervention); a,b,c superscripts with the same letter show a degree of significant difference between both groups (*p* < 0.05). Pairwise comparisons were performed with Bonferroni's adjustment.

*3.2. Differences in Body Composition Variables, HR Variables, UKK Test Measuring, and VO2max between Pretest and Posttest by Participant Group (Control, RW, and NW)*

A mixed-design ANOVA with mean data of body mass (F = 410.13, *p* < 0.001, η<sup>2</sup> <= 0.72) and BMI (F = 412.63, *p* < 0.001, η<sup>2</sup> = 0.71) revealed a significant main effect of participant groups (control, RW and NW). The interaction between group and pretest–posttest intervention showed a significant effect in body mass (F = 113.33, *p* < 0.001, η<sup>2</sup> = 0.58) and BMI (F = 111.73, *p* < 0.001, η<sup>2</sup> = 0.57). Moreover, a repeated-measures ANOVA test between pretest and posttest in the RW and NW groups demonstrated differences in body mass (RW group, *t* = 14.49, *p* < 0.001; NW group, *t* = 15.09, *p* < 0.001), BMI (RW group, *t* = 14.37, *p* < 0.001; NW group, *t* = 15.16, *p* < 0.001), and walking HR (RW group, *t* = −14.36, *p* < 0.001; NW group, *t* = −9.41, *p* < 0.001). This is shown in Figure 2.

**Figure 2.** Differences in body weight and body mass index at pretest and posttest interventions in the three studied groups. \*\*\* *p* < 0.001.

The mean data of walking HR (F = 62.94, *p* < 0.001, η<sup>2</sup> = 0.28) and the HR at the end of the UKK walking test (F = 82.59, *p* < 0.001, η<sup>2</sup> = 0.31) determined by a mixed-design ANOVA revealed a significant main effect of participant groups (control, RW and NW). The interaction between group and pretest–posttest intervention showed a significant effect in walking HR (F = 19.25, *p* < 0.001, η<sup>2</sup> = 0.19) and the HR at the end of the test (F = 21.77, *p* < 0.001, η<sup>2</sup> = 0.21). The HR at the end of the test showed differences between the pretest and posttest (RW group, *t* = 8.99, *p* < 0.001; NW group, *t* = 4.45, *p* < 0.001), while the walking HR during the test also showed significant differences (RW group, *t* = 5.90, *p* < 0.001; NW group, *t* = 5.60, *p* < 0.001) (Figure 3).

The mean data of UKK total time (F = 183.01, *p* < 0.001, η<sup>2</sup> <= 0.53) and UKK fitness index (F = 132.81, *p* < 0.001, η<sup>2</sup> <= 0.45) determined by a mixed-design ANOVA revealed a significant main effect of participant groups (control, RW and NW). The interaction between group and pretest–posttest intervention showed a significant effect in UKK total time (F = 47.55, *p* < 0.001, η<sup>2</sup> <= 0.36) and UKK fitness index (F = 33.55, *p* < 0.001, η<sup>2</sup> < = 0.29). The significant differences between before and after 12 weeks of intervention in terms of UKK test measurements are shown in Figure 4—namely, UKK total time (RW group, *t* = 13.03, *p* < 0.001; NW group, *t* = 8.29, *p* < 0.001) and UKK fitness index (RW group, *t* = −6.79, *p* < 0.001; NW group, *t* = −6.41, *p* < 0.001).

**Figure 3.** Differences in walking heart rate and heart rate at the end of the test in pretest and posttest interventions in the three studied groups. \*\*\* *p* < 0.001.

**Figure 4.** Differences in UKK total time and UKK fitness index in pretest and posttest interventions in the three studied groups. \*\*\* *p* < 0.001.

Finally, the results of the mixed-design ANOVA for VO2max (F = 230.89, *p* < 0.001, η<sup>2</sup> <= 0.58) showed the significant main effect of participant groups (control, RW, and NW). The interaction between groups and pretest–posttest intervention also showed a significant effect in VO2max (F = 60.91, *p* < 0.001, η<sup>2</sup> <= 0.43). Figure 5 shows significant differences in VO2max between pretest and posttest in the RW group (*t* = −14.36, *p* < 0.001) and the NW group (*t* = −9.40, *p* < 0.001). The control group showed no significant differences between pretest and posttest interventions in any variable studied.

**Figure 5.** Differences in VO2max in pretest and posttest interventions in the three studied groups. \*\*\* *p* < 0.001.

#### **4. Discussion**

The objective of the present study was to examine the effects of a 12-week intervention in three groups (control, RW, and NW groups) on anthropometric measurement variables (body mass and BMI), HR variables (walking HR and HR at the end of the test), UKK test measurements (total time and fitness index), and VO2max in older adult women. Given the specific nature of exercise adaptations and the need to maintain muscle mass, muscle strength, and flexibility throughout life, and even more in the ageing process, a comprehensive training programme consisting of resistance, aerobic, and flexibility exercises is recommended [4]. NW can improve muscle strength and flexibility, as well as aerobic endurance capability [35]. Likewise, RW, together with a muscular strength programme, can produce the same improvements as the NW discipline, because the disciplines do not differ considerably [29]. The main finding of this study showed that NW group training resulted in slightly greater benefits than RW group training; nevertheless, both were shown to be valid modalities to improve the functionality and quality of life of people during the ageing process.

In regard to the variable of walking HR, we found that the lowest mean was presented by the RW group, followed by NW. In accordance with a recent systematic review and metaanalysis carried out by Bullo et al. [34], these data contradict the majority of studies. These results could be due to the fact that it has been shown that healthy older adults can maintain their gait speed with or without poles, thus matching the physical demands required [36]. The same results were found in a study by Takeshima et al. [33]. Both disciplines showed improvements after the training programme. These data are in line with those found for participants of the same age range in the literature [28] or for those registered in control groups of physical training programmes [37], which confirms favourable results in the experimental groups of this study. We observed that, after the intervention, RW produced better values than NW in terms of walking HR and HR at the end of the test; NW values

were also significant and showed improvements very similar to those of the RW modality. These data are in accordance with those found by Gomeñuka et al. [35], in which the NW discipline did not result in greater benefits than RW related to participants' quality of life.

As expected, the improvements in the average walking HR were greater in the NW group than in the RW group at the end of the program. These data could be explained by the fact that NW increases the activity (muscular) of the upper part of the body during practice and, with it, the energy expenditure with higher oxygen consumption [38]. If we compare our results with the findings of Pellegrini et al. [28], it can be deduced that NW group participants of the present study showed lower bt/min during the 2 km test. However, in a study by Sugiyama et al. [42], participants were evaluated for 5 km, whereas we studied only 2 km. Therefore, increases in both strength and aerobic capacity contribute to the reduction in submaximal HR when NW and RW are performed at the same walking speed [39]. In the present study, UKK total time was similar for both disciplines. Regarding the variable HR at the end of the test, the NW group presented the best average. In a similar way, we found comparable results for RW, elucidating how both modalities generated improvements in the reduction in mean beats per minute at the end of the programme [35]. Similar improvements were shown for the rest of the variables described above and below (HR, fitness index, and VO2max).

NW and RW are two aerobic activities capable of improving anthropometric measurement through the ageing process, and a 12-week programme using these two modalities, such as that used in the present study, results in significant changes in terms of body mass loss and BMI [41,43]. Although both exercise disciplines showed comparable results, we found that RW produced slightly better results than NW in body mass and BMI after 12 weeks of intervention. According to a study by Figard-Fabre et al. [44], even with a correct NW technique, the difference in energy expenditure is not greater than that in RW. This minimal difference in energy expenditure could explain how RW obtained slightly better results in the current study, underlining that NW has also shown improvements in this regard. These results are not in line with the fact that energy expenditure is higher in the NW pattern, and this would mean a greater body mass loss [28,45].

Given the nature of the NW modality, gait speed is greater with the use of poles versus walking without any help [46]. Although the time to complete the activity was similar, the RW group presented a slightly shorter time. This is consonant with data found by Gomeñuka et al. [35] and contrary to what is found in other studies [31,33,46]. This could be explained by the fact that if the poles do not push the ground in the correct way for the propulsion of the movement, the dynamic stability is impaired; thus, the movement is not as efficient and fast, requiring more time to complete a given distance [47].

In the final measurement, UKK fitness level and VO2max showed slightly higher values in the RW group compared with the NW group, which points to a greater improvement in functional capacities in the former group, compared with the control group. This increase was manifested as an improved UKK fitness level, increased general cardiorespiratory capacity, and higher percentages of VO2max, which were considered the best indicators of lung capacity and air intake. A study by Pellegrini et al. [46] reported NW and RW as acceptable forms of exercise for the ageing population regardless of their VO2max. The results found in this study would contradict those shown in the literature, since, as previously described, NW generally showed higher energy expenditure and, with it, the expectation that UKK fitness level and VO2max values should also be higher in this group [46]. These data could be explained by the fact that if participants' NW technique was incorrect, resulting in a weak NW style instead of the suggested technique, this could decrease the effectiveness of the training programme [28]. Hansen and Smith [48] found that when participants are taught to perform a particularly energetic NW technique, characterised by long strides and pole pushes, oxygen consumption exceeds that measured during walking, by up to 67%. In contrast, in line with the findings of the present study, NW and RW showed similar results, which can be explained by the fact that both modalities share muscle synergies that mainly involve the activation of the muscles of the lower extremities and the trunk. Therefore, walking with the use of poles does not produce considerable changes in the muscular demands of the lower body [31].

If each modality and variable is analysed separately, NW produced greater improvements with respect to RW. In a study carried out by Mikalaˇcki et al. [49], in which they evaluated the effects of a 12-week NW programme on functional capacities using the UKK test, results showed improvements in UKK fitness values, which is consistent with our findings. Other studies on NW have shown that VO2max increases at the end of the intervention [34,50], which is also consistent with our study, showing significant results for NW training in the variables mentioned above.

The outcomes of this study support NW as a secure, viable, and helpful form of physical training that can improve several components of fitness in older adults. RW also has a multitude of other documented benefits, and it is often used as a primary and secondary preventive alternative to PE [4]. Both RW and NW can be performed by individuals or in groups, which may provide social well-being benefits. Additionally, although NW is often performed outdoors, it can also be practised indoors with the use of rubber-tipped poles, turning it into an activity that can be accomplished all year round, even during adverse weather conditions [33]. NW appears to be more effective in providing more cardiorespiratory fitness benefits, compared with RW. Consequently, NW may be more effective than RW in improving and maintaining the overall health and function of adults in the ageing process [51]. Therefore, it is important to know the benefits of both modalities, and it would be convenient to carry out future research in different segments of the older adult population and during longer intervention periods.

In terms of limitations, the present study shows its potential due to the lack of related studies that have compared NW and RW in this population group. On the one hand, the intervention time of 12 weeks should be extended in future research to obtain more significant results, especially in physiological variables and time spent covering the distance of the UKK test. On the other hand, far from being a constraint, the Nordic-walking technique of participants was controlled during the study and supervised by physical exercise specialists. In fact, participants' individual physical limitations were considered in controlling for the range and intensity of the exercise.

Another variable that could have completed the study would have been to evaluate muscular grip strength and, thus, be able to explain the possible adaptations in terms of upper body strength and physiological changes. Regarding the different groups and the modalities used, it is worth highlighting the need to expand the given consideration to the technique when using poles in NW. Additionally, in the context of control, it would be advisable to control the dietary intake of study participants; if the decrease in body mass is to be taken into account, diet is one of the variables most affected. Likewise, evaluating the improvements in the anthropometric measurement of the participants should include changes in the different variables through electrical bioimpedance.

#### **5. Conclusions**

The novelty of this study lies in its comparative results between NW and RW interventions for older adults and, with it, guiding healthy alternatives to improve the quality of life and health in the ageing process. The main findings revealed that, after 12 weeks, NW training resulted in slightly greater benefits than RW training; nevertheless, both were shown to be valid modalities to improve the functionality and quality of life of people during the ageing process.

Moreover, our study suggested that the NW technique is a beneficial training method for improving the physical condition of healthy older adults. The practice of the NW and RW modalities represents an optimal continuity of kinesiological activity, particularly in older adults, to maintain and improve their functional capabilities. The present study showed that 12 weeks of Nordic walking and recreational walking improved HR variables, UKK test measurements, and VO2max. In fact, this research highlighted the clinical importance of chronic exercise and its considerably positive benefits on health and quality

of everyday life. However, caution is required concerning participants' extensive use without the presence of specialists to control the individual training in older people.

**Author Contributions:** Conceptualisation, P.J.R.-M. and F.T.G.-F.; methodology, P.J.R.-M.; formal analysis, P.J.R.-M. and F.T.G.-F.; investigation, N.C. and P.J.R.-M., resources, N.C.; data curation, P.J.R.-M.; writing—original draft preparation, P.J.R.-M.; writing—review and editing, P.J.R.-M., F.T.G.-F. and R.M.-M.; visualisation, P.J.R.-M., F.T.G.-F. and R.M.-M.; supervision, N.C. and R.M.-M.; project administration, N.C. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** This study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of the University of Novi Sad (Serbia) (protocol code 46-06-03/2020-1 at 6 October 2020).

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study. Written informed consent has been obtained from the patients to publish this paper.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** The authors would like to thank the people who participated in the study for the extra time they spent with the test and questionnaires. All of them consented to the acknowledgement.

**Conflicts of Interest:** The authors declare no conflict of interest.
