The physiological responses to walking with and without Power Poles™ were studied by Hendrickson (1993) and by Porcari et al. (1997). Power Poles are specially constructed, rubber-tipped ski poles designed for use during walking. Hendrickson's study group consisted of sixteen fit women (VO2max 50 ml/kg/min) and men (59). They did walk with and without poles on a treadmill with the speeds of 6-7,5 km/h. There were no differences in the responses between males and females. It was found that the use of poles significantly increased oxygen uptake, heart rate and energy expenditure by approximately 20% compared to the walking without poles in fit subjects. In Porcari's study on 32 healthy men and women walking with poles resulted in an average of 23% higher oxygen uptake, 22% higher caloric expenditure and 16% higher heart rate responses compared to walking without poles an a treadmill. RPE values averaged 1,5 units higher with the use of poles and the pattern of responses was similar for men and women.
A dual-motion treadmill Cross Walk has been studied by Knox (1993), Foley (1994) and by Butts et al. (1995) . The Cross Walk Dual Motion Cross Trainer as a motorized treadmill designed to increase the energy cost of walking by incorporating arm activity during walking, thus increasing the muscle mass used during exercise. The activity is not the same as field walking with poles, but can be used as reference to NW. Knox did study thirty-seven 17-35 year old women and they all performed six 5-min steady-state exercises with and without arm activity. Walking with arm activity increased significantly heart rate, ventilation, oxygen uptake and energy expenditure compared to the walking without arm activity. E.g. heart rate increased 17-31 beats per minute. Rating of perceived exertion as well as energy expenditure increased with an average of 14 percent. In Butt's study both the 24-year old women and men were studied with a similar design. In this study arm work increased energy expenditure by 55 % on an average compared to the regular walking, but did increase rating of perceived exertion only little. This was consistent with the results from the Foley, who did study Cross Walk in 24-year-old men.
Rogers at al. (1995) did compare energy expenditure during submaximal walking with Exerstriders® in ten 24 year old fit women. Mean maximal aerobic power (21 vs. 18 ml/kg/min) and heart rate (133 vs. 122 bpm) were significantly greater during the walking with poles compared to walking without. Also the total caloric expenditure in a 30 minute session was significantly greater during pole walking (174 vs. 141 kcal). In contrast, the rating of perceived exertion did not differ significantly between the two conditions.
Laukkanen (1998, unpublished) did compare heart rate during normal and fast walking speeds with and without Exel Walker poles. Ten middle-aged men and women were studied on an indoor hall track. The heart rate increase, measured with telemetric Polar HR monitor, was between 5-12 bpm and 5-17 bpm in women and men.
Gullstrand & Svedenhag (2001) from Sweden did study acute physiological effects on walking on a treadmill with or without poles. This study on 13 55-year old subjects did show that VO2max, VE, blood lactate and HR did increase, but RPE (rating of perceived exertion) remained unchanged in NW compared to regular walking
The effects of Exel's Nordic Walker pole training on heart rate responses was studied in ten men and women. Their heart rates were 5-12 and 5-17 beats x min-1 higher for moderate and vigorous Nordic Walking in an indoor sports hall in comparison with walking without poles (Laukkanen 1998).
In the study published by the Cooper Instiute group from Texas, USA the metabolic cost of NW was compared to normal walking in 22 31-year-old men and women (Morss et al. 2001, Church et al. 2002). Participants of this study did walk on an outdoor 200-m track with Cosmed K4b for oxygen consumption and Polar Vantage heart rate monitor for HR measurements. Study indicated significant increases of oxygen consumption (20% on average), caloric expenditure and HR in NW compared to normal walking. The range of increase was large, i.e. in oxygen consumption 5-63% indicating differences in poling intensity and technique. Perceived exertion did not differ between the walks. Same group did also compare separately metabolic cost of high intensity poling (Jordan et al. 2001). In high intensity poling NW increased HR 35 bpm on an average compared to regular walking.
In a study by Willson et al. (2001) the purpose was to determine whether walking with poles reduces loading to the lower extremity during level over ground walking. Three-dimensional gait analysis was conducted on 13 healthy adults who completed 10 walking trials using three different poling conditions (selected poles, poles back, and poles front) and without the use of poles (no poles). Results did show that there were differences in kinetic variables between walking with and without poles. The use of walking poles enabled subjects to walk at a faster speed with reduced vertical ground reaction forces, vertical knee joint reaction forces, and reduction in the knee extensor angular impulse and support moment, depending on the poling condition used.
A study done in Germany by Ripatti (2002) 24 individuals (48±8 yrs) did NW for 6 weeks 2 times weekly for 60 min (65-85 %HRmax). This improved their endurance capasity even walking at lower speed.
Mänttäri et al (2004) did conduct a pilot study for Kukkonen-Harjula et al. intervention study (2004). In this pilot they compared the cardiorespiratory and musculoskeletal responses of NW and W in field conditions in middle-aged women, with three self-guided exercise intensities. After screening examinations 20 middle-aged women performed a maximal exercise test on a treadmill with poles. All the subjects were familiar with Nordic walking or cross-country skiing. These results showed that Nordic walking increased the mean HR compared to regular walking only from 2.6% to 4.9% and the mean VO2 from 2.5% to 10.8%, during the three different self-guided walking intensities. This increase seems to be due to the increased muscle activity in the upper body muscle groups. Compared to previous studies the statistically significant mean differences between NW and W were modest.