Validity and Reliability of the PowerTap P1 and Garmin Vector 2 Power Pedals

The development of the cycle-mounted power meter has allowed performance (e.g. power output) to be monitored using the athlete’s own bike (Earnest, Wharton, Church and Lucia, 2005, Journal of Strength and Conditioning Research, 19, 344–348). A popular option for amateur cyclists is the pedal-based power meter as they allow the flexibility of transferring between bikes but are also cheaper than the ‘gold standard’ SRM Powermeter. Currently, two of the most common pedal-based power meters are the PowerTap P1 (P1) and Garmin Vector 2 (V2) pedals. The aims of this study were to 1) compare the Lode Excalibur Sport with the P1 and V2 pedals and 2) investigate the test-retest reliability of the P1 and V2 pedals. Following institutional ethics approval, ten participants completed four 5 min sub-maximal cycling bouts (100, 150, 200 and 250 W), a 2 min maximal time-trial and two 10 s maximal sprints. Each participant completed the protocol on four occasions, two using the P1 pedals and two using the V2 pedals. Significant differences were seen between the Lode Excalibur Sport and the P1 pedals at 100 W (100.0±0.0 vs. 100.4±3.8, P = 0.006), 150 W (150.0±0.0 vs. 151.2±2.7, P = 0.006), 200 W (200.0±0.0 vs. 201.6±2.5, P = 0.001), 250 W (250±0.0 vs. 252.2±2.6, P = 0.006) and during the all-out sprints (963.7±111.0 vs. 1026.4±116.2, P = 0.020, ES = 0.55). Significant differences were also seen between the Lode Excalibur Spot and the V2 pedals at 100 W (100.0±0.0 vs. 104.6±4.2, P < 0.001), 150 W (150.0±0.0 vs. 156.3±4.9, P < 0.001), 200 W (200.0±0.0 vs. 207.2±6.0, P = 0.001), 250 W (250±0.0 vs. 261.4±7.2, P < 0.001) and during the all-out sprints (973.9±100.5 vs. 1026.1±95.5, P = 0.018, ES = 0.53). However, no significant differences were seen during the 2 min time-trial between the Lode Excalibur Sport and the P1 pedals (402.7±57.1 vs. 398.8±54.8, P = 0.718, ES = 0.07) or the V2 pedals (400.9±46.2 vs. 402.2±48.4, P = 0.779, ES = 0.03).The coefficient of variation for the P1 and V2 pedals ranged from 0.57–1.28% and 0.73–2.7%, respectively, during the sub-maximal cycling bouts. These results suggest that some care should be taken when using the P1 and V2 pedals during sprint performance. Results also suggest that during sub-maximal power outputs, both the P1 and V2 pedals are reliable.