# Does Power Output at Critical Power Intensity Interchange between Cycling and Running?
## 4 Discussion  
The main purpose of the present study was to determine whether power output at CP intensity could be interchangeable between cycling and running segments. Although both the power meters and the sport-specific gestures in each of these disciplines are different,  
Figure 3: Critical Power records between the cycling and running disciplines. Columns shown in black for absolute power and gray for power relative to body mass. * \(p\) < 0.001. Figure 2: Power records during the 9/3 Stryd CP test. Columns shown in black for absolute power and gray for power relative to body mass. triathletes could be ideal participants for this type of study due to their previous familiarity with both technical gestures, pedaling and stride, respectively. To the best of our knowledge, this study provides the first comparison of CP values between cycling and running. While a theoretical basis for power application exists in cycling [10; 13; 30; 31; 32; 33; 34], a more detailed examination of running power is necessary. Firstly, it is important to note that the available information on running power is limited [35]. However, the concept of power in running has been systematically reviewed [36; 37]. The validity and reliability of one of the main devices for measuring power output [38], the Stryd running-power meter (Stryd Summit Power Meter, Boulder, CO, USA) has been studied at different running speeds [39], as well as in other modalities such as walking [40] and trail walking [41]. Additionally, data training metrics have been analyzed with this device [42; 43; 44]. The CP concept has been investigated from a physiological perspective, including its relationship to ventilatory thresholds and maximum oxygen uptake [20] as well as its association with physiological variables such as oxygen consumption [45] and changes in power as functions of different intervals [46]. One of the main advantages of the Stryd running-power meter is its practical applications for data collection in both training and competition settings, in contrast to laboratory-based devices [47]. Secondly, in relation to running power, it is worth highlighting a study by [PERSON] et al. [20], in which CP was determined with respect to ventilatory thresholds and maximum oxygen uptake using the same 9/3-minute Stryd CP test proposed by the [PERSON] group. In that study, conducted on 15 high-caliber athletes, higher values of CP were observed (4.67 \(\pm\) 0.42 W/kg) compared with those found in our trained triathletes (4.23 \(\pm\) 0.51 W/kg). Similarly, higher values were observed for the 15 high-caliber athletes in the two efforts performed in the running test to determine the CP, in the maximum efforts of both 9 min (4.91 \(\pm\) 0.42 W/kg vs. 4.40 \(\pm\) 0.40 W/kg) and 3 min (5.39 \(\pm\) 0.44 W/kg vs. 4.66 \(\pm\) 0.52 W/kg) [20]. It is important to consider the protocol used for determination of CP in running, and attention should also be given to the study of [PERSON] et al. [16], in which the CP or rFTPw values of nine recreational triathletes were lower (3.7 \(\pm\) 0.5 W/kg) than those found in our study of trained triathletes (4.23 \(\pm\) 0.51 W/kg). Therefore, the CP values of the present study (4.23 \(\pm\) 0.51 W/kg) are justified by the levels of the 18 trained male triathletes [21], as they are lower than those determined for a group of 15 high-caliber athletes (4.67 \(\pm\) 0.42 W/kg) by [PERSON] et al. [20] and higher than those found in recreational triathletes (3.7 \(\pm\) 0.5 W/kg) by [PERSON] et al. [16]. Finally, an in-depth analysis is necessary to extrapolate on power output between cycling and running, and vice versa. Two main considerations need to be taken into account, namely, the differences between the power meters and the specific gestures involved in each sport. Running involves a semi-open-chain cyclic gesture, while cycling is a closed-chain cyclic movement [48].