Time to Exhaustion at the Respiratory Compensation Point in Recreational Cyclists

Interchangeability between the Data Obtained by Two Powermeters during Road Cycling Competitions: A Case Study

Various power meters are used to assess road-cycling performance in training and competition, but no previous study has analyzed their interchangeability in these conditions. Therefore, the purpose was to compare the data obtained from two different power meters (PowerTap vs. Power2Max) during cycling road races. A national-level under-23 male competitive cyclist completed six road-cycling official competitions (five road races and one individual time trial), in which power output was simultaneously registered with the two power meters. After this, the main power output variables were analyzed with the same software. The average and critical power obtained from the PowerTap power meter were slightly lower than from the Power2Max power meter (3.56 ± 0.68 and 3.62 ± 0.74 W·kg^-1, 5.06 and 5.11 W·kg^-1, respectively), and the correlations between both devices were very high (r ≥ 0.996 and p < 0.001). In contrast, the PowerTap power meter registered a significantly higher (p < 0.05) percentage of time at <0.75 and >7.50 W·kg^-1 and power profile at 1, 5 and 10 s. In conclusion, the data obtained in competitions by the two power meters were interchangeable. Nevertheless, the Power2Max power meter underestimated the pedaling power during short and high-intensity intervals (≤10.0 s and >7.50 W·kg^-1) compared to the PowerTap power meter. Therefore, the analysis of these efforts should be treated with caution.

Pole Walking Is Faster but Not Cheaper During Steep Uphill Walking

PURPOSE

The aim of this study was to compare pole walking (PW) and walking without poles (W) on a steep uphill mountain path (1.3 km, 433 m of elevation gain) at 2 different intensities: a maximal effort that would simulate a vertical kilometer intensity and a lower intensity (80% of maximal) simulating an ultratrail race.

METHODS

On the first day, we tested the participants in the laboratory to determine their maximal physiological parameters, respiratory compensation point, and gas exchange threshold. Then, they completed 4 uphill tests along a mountain path on 4 separate days, 2 at their maximum effort (PWmax and Wmax, randomized order) and 2 at 80% of the mean vertical velocity maintained during the first 2 trials (PW80 and W80, randomized order). We collected metabolic data, heart rate, blood lactate concentration, and rating of perceived exertion at the end of each trial. We also collected rating of perceived exertion at every 100 m of elevation gain during PW80 and W80.

RESULTS

Participants completed the maximal effort faster with poles versus without poles (18:51 [03:12] vs 19:19 [03:01] in min:s, P = .013, d = 0.08, small). Twelve of the 15 participants (80%) improved their performance when they used poles. During PW80 and W80, none of the physiological or biomechanical parameters were different.

CONCLUSION

In the examined condition, athletes should use poles during steep uphill maximal efforts to obtain the best performance. Conversely, during submaximal effort, the use of poles does not provide advantages in uphill PW.

Exercise duration: Independent effects on acute physiologic responses and the need for an individualized prescription

An individualization of exercise prescription is implemented mainly in terms of intensity but not for duration. To survey the need for an individualized exercise duration prescription, we investigated acute physiologic responses during constant‐load exercise of maximal duration (t_max) and determined so‐called duration thresholds. Differences between absolute (min) and relative terms (% t_max) of exercise duration were analyzed. Healthy young and trained male and female participants (n = 11) performed an incremental exercise test and one t_max constant‐load exercise test at a target intensity of 10% of maximal power output below the second lactate turn point (LTP₂). Blood lactate, heart rate, and spirometric data were measured during all tests. t_max was markedly different across subjects (69.6 ± 14.8 min; range: 40–90 min). However, distinct duration phases separated by duration thresholds (DTh) were found in most measured variables. These duration thresholds (except DTh1) were significantly related to t_max (DTh2: r² = 0.90, p < 0.0001; DTh3: r² = 0.98, p < 0.0001) and showed substantial interindividual differences if expressed in absolute terms (DTh2: 24.8 ± 6.0 min; DTh3: 47.4 ± 10.6 min) but not in relative terms (DTh2: 35.4 ± 2.7% t_max; DTh3: 67.9 ± 2.4% t_max). Our data showed that (1) maximal duration was individually different despite the same relative intensity, (2) duration thresholds that were related to t_max could be determined in most measured variables, and (3) duration thresholds were comparable between subjects if expressed in relative terms. We therefore conclude that duration needs to be concerned as an independent variable of exercise prescription.

A comparative analysis of critical power models in elite road cyclists

The aims of this study were to compare four different critical power model's ability to ascertain critical power and W' in elite road cyclists, while making comparison to power output at respiratory compensation point, work rate (J·sec-1) at Wmax, and the work done above critical power during the Wmax test in relation to the W'. Ten male, elite endurance cyclists (V̇O2max ​= ​71.9 ​± ​5.9 ​ml ​kg-1·min-1) all familiar with critical power testing, participated in 3 testing sessions comprising 1. 15-s isokinetic (130 ​rpm) sprint, 1-min time trial, a ramp test to exhaustion, 2-3. a 4-min and/or 10-min self-paced maximal time trial separated by at least 24-h but limited to a 3-week period. The main findings show that all critical power models provided different W' (F(1.061,8.486) ​= ​39.07, p ​= ​0.0002) and critical powers (F(1.022,8.179) ​= ​32.31, p ​= ​0.0004), while there was no difference between each model's critical power and power output at respiratory compensation point (F(1.155, 9.243) ​= ​2.72, p ​= ​0.131). Differences between models or comparisons with respiratory compensation point were deemed not clinically useful in the provision of training prescription or performance monitoring if the aim is to equal work rate at compensation point. There was also no post-hoc difference between work completed at Wmax (kJ) (p ​= ​0.890) and W' using the nonlinear-3 model. Further research is required to investigate the physiological markers of intensity associated with respiratory compensation point and critical power work rate and the bioenergetic contribution to W'.