Effects of 12 weeks of Nordic Walking and XCO Walking training on the endurance capacity of older adults

With increasing age, endurance capacity declines and can lead to functional problems in everyday life [1‐6]. Several studies in recent years have used Nordic Walking as the means of choice to achieve positive effects on the cardiovascular and musculoskeletal system because of the higher activity in the muscles involved in the Nordic Walking (NW) technique [4, 7‐10].

For NW, several studies with different patient groups (aged 40 years and older) have demonstrated positive effects on oxygen uptake, perceived exertion [11, 12], the anaerobic threshold [13‐17] and the reduction of body fat [17, 18]. However, the former studies with NW varied in their study design (cross-sectional, longitudinal including an intervention), setting (laboratory, field), walking area (treadmill, walking track), test protocol (increasing speed, elevation of pitch angle, distance, duration), and technical instructions [19‐26]. In addition, most of the NW studies had measurements in laboratory set-ups, although NW is an outdoor endurance training form. For example, two intervention studies with NW were conducted for 50 min, three times a week, for 6 weeks [20] and 40 min, four times a week, for 13 weeks [22]. Chomiuk et al. [20] showed, for example, higher oxygen uptake values after their NW training intervention with patients over 65 years of age compared to an inactive control group. Kukkonen-Harjula et al. [22] compared Walking (W) with and without poles and demonstrated similar reductions of heart rates and lactate concentrations in both groups with women aged 50 to 60 years. Preuss et al. [27] compared NW, W, Power Walking and Jogging in 32 healthy persons with a mean age of 46 years. The authors showed significant higher values in heart rate and relative oxygen uptake during NW, compared with W. As a possible explanation a more difficult arm-leg coordination during NW was assumed [27]. Furthermore, the former NW studies with field tests were cross-sectional in their design and varied extensively in their testing and training protocols [27‐32]. A current review [9] gives a comprehensive overview of the impact of Nordic Walking in the second half of lifetime and displays the literature concerning the effectiveness and safety of Nordic Walking in the therapeutic rehabilitation of patients of an advanced age. Another review [10] highlighted the health benefits of NW as well. Within the reviews, the authors concluded that heart rate and oxygen uptake values were higher when compared with W [9, 10].

Similar effects on the cardiovascular system are attributed to XCO Walking (XCO), another endurance training alternative [33]. For XCO Walking, participants use two XCO trainers (a single XCO trainer is a 27 cm long closed aluminium tube filled with movable slate granules, fixed weight: 630–650 g). Participants grab one XCO trainer with each hand and move them alternating back and forth during normal walking. With each swing to the front and back the slate granules hit the end caps of the XCO trainers, resulting in the XCO-typical “reactive impacts”, producing a reflexive activation of antagonist shoulder muscles [34].

At present, there are just two studies that examined potential effects of XCO Walking. Two cross-sectional studies have looked at the muscle activity of the biceps and triceps, but not during the usual XCO Walking technique [35], and have compared heart rate, oxygen uptake and energy consumption during the usage of the XCO trainers versus dumbbells [36]. Only one study has implemented a longitudinal design with an intervention period [33]. These authors [33] compared XCO Walking with walking without any tool in untrained women (40–60 years). Unfortunately, the XCO group trained with the interval endurance method and the walking group with the continuous endurance method. Due to this flaw, it is not obvious whether the effects are a result of using the XCO trainers or because of the different training methods.

In summary, for NW, there are results available for adults and several patient groups, but for XCO, the research knowledge is very limited. Both the NW and XCO studies solely included healthy adults up to 60 years old or specific patient groups; however, the two endurance training alternatives, NW and XCO, could be reasonable ways to positively influence the endurance capacity of older adults aged 60 years and older, as well as to prevent cardiovascular diseases, for example. It is questionable whether these two different technique models, with the dynamic activation of m.biceps brachii and m.triceps brachii during NW, on the one hand, and the isometric activation of these two muscles during XCO, on the other hand, lead to similar effects on the endurance capacity of older adults.

The aim of this study was to examine the physiological effects of two endurance training alternatives (NW versus XCO) on the endurance capacity of healthy older adults (aged 60 years and older).

The characteristics of the sample displayed no significant differences between the two groups, NW and XCO, which was indicative of a successful randomisation (see Table 1).

The absence of significant differences regarding the participants’ characteristics is indicative of a successful randomisation to either the NW or the XCO group prior to the first training session.

The NW group showed decreased heart rate, lactate concentration and energy consumption with the same walking speeds at T1 and T2 after the training period, particularly at slower to moderate walking speeds. Further, the NW group decreased their VO₂ in moderate to high walking speeds. The XCO group displayed no significant differences for heart rate for the comparison before and after the training period. The XCO group demonstrated decreases in lactate concentration and VO₂ in slow to high walking speeds (with the exception of 1.8 m/s). The reductions in heart rate in the NW group and lactate concentrations in both groups through the training period can be interpreted as an improved cardiovascular function or as a response to a reduced metabolic demand. Regarding VO₂, the XCO group revealed higher average (33%) decreases than the NW group (12%). However, our study was not conducted in a crossover design and both groups completed the outdoor field endurance test before and after the 12 weeks of training only with their assigned training tool (XCO trainer or NW poles). Therefore, a direct comparison between the two training groups is not possible.

In this study, the increase in the metabolic demand was given by the speed of each walking speed stage. With this in mind, the change (decrease) in VO₂ after the training period during the same walking speed can be interpreted as a change of efficiency in the older adults. Usually, this can be the case due to the technical component of this type of exercise although all participants have been taught within 8 sessions and realized the correct technique. If the training resulted in improved efficiency (decreased VO₂), the reduction in lactate concentration and heart rate could possibly be explained as a response to the reduction in the metabolic demand for the exercise. The positive changes in the measured parameters imply that both training tools were effective for maintaining (improving) endurance capacity in healthy older adults (60 years and older). To further study these aspects, an identical exhaustive stress test without the training tools (possibly standardized on a treadmill) before and after the training period can provide further insights.

A study by Kukkonen-Harjula and colleagues [22] demonstrated improvements in both the NW (2.5 ml/min/kg) and the Walking (W) group (2.6 ml/min/kg) in peak VO₂, energy consumption and lactate concentration after 13 weeks of NW and W. However, their sample included women up to 60 years old, their study included a testing protocol for submaximal and maximal exercise performance with both NW and W for all participants, and the authors provided only two instruction sessions on NW and W. However, authors did not find statistically significant differences between the study groups in the submaximal performance tests and no significant interaction [22]. Other considerations concerning NW have been predominantly in cross-sectional designs in the laboratory and in the field as well [21, 23, 27‐29, 31]. These author groups demonstrated the advantages of NW in oxygen uptake, energy consumption, lactate concentration and heart rate in comparison with normal walking. For XCO, there are only a few studies, for example, by Stengel and colleagues [33], who showed improved oxygen uptake after their intervention with the XCO trainers. These authors [33] compared XCO Walking with normal walking; however, a main problem with their study and a limitation of its relevance is the application of two different training methods in the two groups: Walking (W) and XCO Walking (XCO). The W group trained with the continuous endurance method, whereas the XCO group received interval training. Due to this flaw, one could not conclude whether the effects resulted from the different training tools or the endurance methods. Additionally, their participants were 29 untrained women between 40 and 60 years of age. The same author group displayed higher cardio-pulmonary, as well as metabolic stress (oxygen uptake, energy consumption, heart rate) in participants using the XCO trainers in contrast to using dumbbells with fixed weights [36].

Altogether, comparisons between the studies mentioned are difficult due to differences in the studies’ design, samples, measurement methods and interventions, and should be taken as additions that lead to a more comprehensive picture of different ways to improve or maintain endurance capacity, particularly for the target group of older adults aged 60 years and older. This study provides relevant results regarding the two training tools, Nordic Walking poles and XCO trainers, to improve endurance capacity in older adults.

The advantages of this study are the identical days and times-of-day of the (parallel) training sessions, the same instructors, and the same training methods, walking speeds and distances. Furthermore, this study consisted of 4 weeks of technical instruction training and 12 weeks of endurance training, resulting in a total intervention duration of 16 weeks. Compared with other studies [20, 22, 33] in this field, it is one of the longest intervention periods. The intervention design of this study is similar to the recommendations by Skorkowska-Telichowska et al. in their review, who suggest NW with professional trainers 2–3 times a week over at least 3 months. Based on their review, these authors conclude that the positive training effects can be maintained over 6–9 months after the training ends [9].

Our study examined the effects of NW and XCO training on the endurance capacity. With the everyday life of older adults in mind, positive effects through NW and XCO training on the functional capacity of older adults can also be an important aspect. For example, Parkatti et al. [4] observed positive effects of NW and Walking on different functional tests with significant differences compared to an inactive control group. These authors had 40 older adults (mean age of 69 years) doing 9 weeks with two times week and 60 min per session. However, these authors merged their walking and NW groups to one intervention group and no further statements regarding the two forms NW versus Walking can be made [4].

In conclusion, both Nordic Walking and XCO Walking are suitable endurance training alternatives for older adults (60 years and older) to positively effect heart rate, lactate concentration and oxygen uptake as parameters of endurance capacity. Following 8 technical instruction sessions, the participants of both training groups reached similar decreases in these parameters by realising training intensities between 60 and 85% of their individual peak heart rates in 24 training sessions in the locality of 2 km from the starting point. Through the training with both NW poles and XCO trainers, these changes can be interpreted as a change of efficiency. This study is one of the first to provide the (long-term: 12 weeks) results of identical and systematic endurance training using Nordic Walking poles and XCO trainers in persons aged 60 years and older. Both NW and XCO are suitable endurance training alternatives to positively influence the efficiency of the cardiovascular system and can result in maintained performance to counteract age-related degradation processes.