Validity and Reliability of the PowerCal Device for Estimating Power Output During Cycling Time Trials

Caveats and Recommendations to Assess the Validity and Reliability of Cycling Power Meters: A Systematic Scoping Review

A large number of power meters have become commercially available during the last decades to provide power output (PO) measurement. Some of these power meters were evaluated for validity in the literature. This study aimed to perform a review of the available literature on the validity of cycling power meters. PubMed, SPORTDiscus, and Google Scholar have been explored with PRISMA methodology. A total of 74 studies have been extracted for the reviewing process. Validity is a general quality of the measurement determined by the assessment of different metrological properties: Accuracy, sensitivity, repeatability, reproducibility, and robustness. Accuracy was most often studied from the metrological property (74 studies). Reproducibility was the second most studied (40 studies) property. Finally, repeatability, sensitivity, and robustness were considerably less studied with only 7, 5, and 5 studies, respectively. The SRM power meter is the most used as a gold standard in the studies. Moreover, the number of participants was very different among them, from 0 (when using a calibration rig) to 56 participants. The PO tested was up to 1700 W, whereas the pedalling cadence ranged between 40 and 180 rpm, including submaximal and maximal exercises. Other exercise conditions were tested, such as torque, position, temperature, and vibrations. This review provides some caveats and recommendations when testing the validity of a cycling power meter, including all of the metrological properties (accuracy, sensitivity, repeatability, reproducibility, and robustness) and some exercise conditions (PO range, sprint, pedalling cadence, torque, position, participant, temperature, vibration, and field test).

The reproducibility of 10 and 20km time trial cycling performance in recreational cyclists, runners and team sport athletes

OBJECTIVES

This study aimed to determine the reliability of 10 and 20km cycling time trial (TT) performance on the Velotron Pro in recreational cyclists, runners and intermittent-sprint based team sport athletes, with and without a familiarisation.

DESIGN

Thirty-one male, recreationally active athletes completed four 10 or 20km cycling TTs on different days.

METHODS

During cycling, power output, speed and cadence were recorded at 23Hz, and heart rate and rating of perceived exertion (RPE) were recorded every km. Multiple statistical methods were used to ensure a comprehensive assessment of reliability. Intraclass correlations, standard error of the measurement, minimum difference required for a worthwhile change and coefficient of variation were determined for completion time and mean trial variables (power output, speed, cadence, heart rate, RPE, session RPE).

RESULTS

A meaningful change in performance for cyclists, runners, team sport athletes would be represented by 7.5, 3.6 and 12.9% improvement for 10km and a 4.9, 4.0 and 5.6% for 20km completion time. After a familiarisation, a 4.0, 3.7 and 6.4% improvement for 10km and a 4.1, 3.0 and 4.4% would be required for 20km.

CONCLUSIONS

Data from this study suggest not all athletic subgroups require a familiarisation to produce substantially reliable 10 and 20km cycling performance. However, a familiarisation considerably improves the reliability of pacing strategy adopted by recreational runners and team sport athletes across these distances.

Sodium bicarbonate improves 4 km time trial cycling performance when individualised to time to peak blood bicarbonate in trained male cyclists

The aim of this study was to investigate the effects of sodium bicarbonate (NaHCO₃) on 4 km cycling time trial (TT) performance when individualised to a predetermined time to peak blood bicarbonate (HCO₃^-). Eleven male trained cyclists volunteered for this study (height 1.82 ± 0.80 m, body mass (BM) 86.4 ± 12.9 kg, age 32 ± 9 years, peak power output (PPO) 382 ± 22 W). Two trials were initially conducted to identify time to peak HCO₃^- following both 0.2 g^.kg^-1 BM (SBC2) and 0.3 g^.kg^-1 BM (SBC3) NaHCO₃. Thereafter, on three separate occasions using a randomised, double-blind, crossover design, participants completed a 4 km TT following ingestion of either SBC2, SBC3, or a taste-matched placebo (PLA) containing 0.07 g^.kg^-1 BM sodium chloride (NaCl) at the predetermined individual time to peak HCO₃^-. Both SBC2 (-8.3 ± 3.5 s; p < 0.001, d = 0.64) and SBC3 (-8.6 ± 5.4 s; p = 0.003, d = 0.66) reduced the time to complete the 4 km TT, with no difference between SBC conditions (mean difference = 0.2 ± 0.2 s; p = 0.87, d = 0.02). These findings suggest trained cyclists may benefit from individualising NaHCO₃ ingestion to time to peak HCO₃^- to enhance 4 km TT performance.

Influence of Velotron chainring size on Wingate anaerobic test

OBJECTIVES

This study compared an 85-tooth versus the standard 62-tooth chainring for power outputs during a Wingate test using a Velotron electromagnetically-braked cycle ergometer.

DESIGN

All participants completed trials using both chainring sizes in a repeated-measures cross-over design.

METHODS

Resistance-trained male participants (n=20, 24.6±4.5years) performed two Wingate tests separated by at least 48h. Peak power (PP), mean power (MP), fatigue index (FI), peak cadence, mean cadence, and total work (TW) were recorded.

RESULTS

Peak power was not significantly different (p=0.10) between trials (62-tooth=1111±187W vs. 85-tooth=1188±103W). However, MP, mean cadence, and TW were significantly greater (p<0.01) for the 85-tooth trial (869±114W, 131±16rpm, and 26,063±3418J) compared to the 62-tooth test (673±136W, 102±24rpm, and 20,199±4066J). Fatigue index was reduced during the 85-tooth trial (49.9±9.1% vs. 61.6±8.8%; p<0.01). Agreement was poor with most ICCs≈0.19 and large SEMs.

CONCLUSIONS

The two options for chainrings on Velotron cycle ergometers should not be interchangeably used with the Wingate test software; the 62-tooth ring is recommended for most applications. Individuals who can attain peak cadence >180rpm have less variability and tend to achieve higher power outputs on the 62-tooth ring. We suspect that the manufacturer's software limits peak cadence to 182rpm when using the 85-tooth chainring.

The effects of block training on pacing during 20-km cycling time trial

The aim of this study was to determine the effects of block training (BL) on pacing during a 20-km hilly cycling time trial (TT) in trained cyclists. Twenty male cyclists were separated into 2 groups: control and BL. The training of each cyclist was monitored during a period of 3 weeks. In the first week cyclists performed an overload period of 7 consecutive days of high-intensity interval training followed by 2 weeks of normal training. Cyclists performed 1 TT before intervention and 2 TT after 7 and 14 days at the end of training. Each training session consisted of 10 sets of 3 repeated maximal-effort sprints (15, 30, and 45 s) with an effort/recovery duration ratio of 1:5. The main finding of this study was that the power output displayed a significantly higher start from the start until the halfway point of the TT (p < 0.05). Additionally, power output was characterized by a significant higher end spurt in the final 2 km in the BL after 2 weeks at the end of training (p < 0.05). In addition, after 2 weeks at the end of the overload period the distribution of cadence was significantly lower throughout the TT (p < 0.01). Therefore, a short period of consecutive days of intense training enhances cycling performance and changes the power output in the beginning and final part of the TT in trained cyclists.