Intensity of Nordic Walking in young females with different peak O2 consumption

The purpose of this cross-sectional study was to determine the physiological reaction to the different intensity Nordic Walking exercise in young females with different aerobic capacity values. Twenty-eight 19-24-year-old female university students participated in the study. Their peak O2 consumption (VO2 peak kg(-1)) and individual ventilatory threshold (IVT) were measured using a continuous incremental protocol until volitional exhaustion on treadmill. The subjects were analysed as a whole group (n = 28) and were also divided into three groups based on the measured VO2 peak kg(-1) (Difference between groups is 1 SD) as follows: 1. >46 ml min(-1) kg(-1) (n = 8), 2. 41-46 ml min(-1) kg(-1) (n = 12) and 3. <41 ml min(-1) kg(-1) (n = 8). The second test consisted of four times 1 km Nordic Walking with increasing speed on the 200 m indoor track, performed as a continuous study (Step 1 - slow walking, Step 2 - usual speed walking, Step 3 - faster speed walking and Step 4 - maximal speed walking). During the walking test expired gas was sampled breath-by-breath and heart rate (HR) was recorded continuously. Ratings of perceived exertion (RPE) were asked using the Borg RPE scale separately for every 1 km of the walking test. No significant differences emerged between groups in HR of IVT (172.4 +/- 10.3-176.4 +/- 4.9 beats min(-1)) or maximal HR (190.1 +/- 7.3-191.6 +/- 7.8 beats min(-1)) during the treadmill test. During maximal speed walking the speed (7.4 +/- 0.4-7.5 +/- 0.6 km h(-1)) and O2 consumption (30.4 +/- 3.9-34.0 +/- 4.5 ml min(-1) kg(-1)) were relatively similar between groups (P > 0.05). However, during maximal speed walking, the O2 consumption in the second and third groups was similar with the IVT (94.9 +/- 17.5% and 99.4 +/- 15.5%, respectively) but in the first group it was only 75.5 +/- 8.0% from IVT. Mean HR during the maximal speed walking was in the first group 151.6 +/- 12.5 beats min(-1), in the second (169.7 +/- 10.3 beats min(-1)) and the third (173.1 +/- 15.8 beats min(-1)) groups it was comparable with the calculated IVT level. The Borg RPE was very low in every group (11.9 +/- 2.0-14.4 +/- 2.3) and the relationship with VO2and HR was not significant during maximal speed Nordic Walking. In summary, the present study indicated that walking is an acceptable exercise for young females independent of their initial VO2 peak level. However, females with low initial VO2 peak can be recommended to exercise with the subjective 'faster speed walking'. In contrast, females with high initial VO2 peak should exercise with maximal speed.