Validity of Bar Sensei in Determining Barbell Velocity and a Novel Measurement of Starting Strength

Zachary J. Switaj, Dustin J. Oranchuk, Tracey Robinson -- Adams State University (Alamosa, Colorado)

(Presented at the ACSM Rocky Mountain chapter meeting, April 2016)


Velocity based training (VBT) can be used to determine loading, track progress and monitor fatigue in the weight-room.  Traditionally, technologies such as force plate systems or linear position transducers (LPTs) were needed to implement VBT.  Force plates and LPTs are often outside the budget of many programs.  Accelerometer systems have become popular for implementing VBT as they are significantly more affordable.  The Bar Sensei™ accelerometer by Assess2Perform™ (Boulder, CO), claims to accurately measure traditional VBT metrics such as peak velocity, as well as a novel measurement called POP-100, which measures the bar velocity during the first 100 ms of the concentric lift, often referred to as “starting strength”.

PURPOSE: The aim of the study was to determine the validity and reliability of the Bar Sensei™ for determining bar velocity and POP-100 during the squat compared to a standard force plate system.

METHODS: The 7 volunteers had 6.57 ± 2.23 years of squatting experience and had a mean 1RM squat of 130.7 ± 59 kilograms.  After completing a warm-up, each participant performed three squats at 20, 40, 60 and 80% of their 1RM.  All squats were performed on a force plate system (Pasco Scientific, Roseville CA), sampling at 500 Hz, with the Bar Sensei™ attached to the barbell.  Force plate data was collected using Pasco Capstone™ software and was analysed in a custom Microsoft Excel spreadsheet.

RESULTS: Paired t-test’s showed a significant difference (p<0.05) between measurement devices.  When all 84 lifts were analyzed, the Bar Sensei™ measured 0.12 m/s and 0.15 m/s higher than the force plates for peak velocity and POP-100, respectively.  However, at 80% of participants’ 1RM, paired t-test’s showed that peak velocity was not significantly different based upon measurement device, p=0.419.  Across all loads, there is a significant linear relationship between both peak velocity (r=0.44) and POP-100 (r=0.92) measured by the Bar Sensei and force plates, p<0.001.  

CONCLUSION: While found to measure both peak velocity and POP-100 significantly higher than a force plate, the Bar Sensei™ appears to be a reliable measurement tool, especially at higher workloads, for tracking data over time.  Future analysis should focus on additional metrics such as mean velocity and a variety of exercises to prove the worth of this promising device.