Access to more affordable technologies such as accelerometers and linear position transducers that sync with mobile phones and tablet devices has lead to an increase in the monitoring of bar speed in the weight room. In turn, a substantial increase in research on how bar speed can be practically implemented for athletes has been developed. Some coaches use a specific velocity drop-off points (e.g., 10%) as the threshold for terminating a set in effort to maintain high quality repetitions. Others use barbell velocity to predict 1RM via simple linear regression equation. Bar velocity is also used by some coaches to assess fatigue and recovery status by evaluating bar speed during a standardized movement with a standardized load. What remains to be determined is what variables explain or contribute to bar speed and more importantly, how bar speed relates with performance markers such as sprinting speed.
A new study published ahead of print in the Journal of Strength and Conditioning Research evaluated relationships between bar speed characteristics during the back squat with anthropocentric, training experience and athletic performance variables. A sample of 21 collegiate athletes (13 football players and 8 softball players) from an NAIA institution participated in the study. Anthropmetry, including size, stature and femur length and training history (years of training with the back squat and recent frequency of use) was acquired at the laboratory. Sprinting speed over 36.6. m was evaluated on an outdoor football field and the best time from two attempts was recorded. Following the sprint, all subjects were tested in the barbell back squat for 1 RM. During the squat, a linear position transducer (Tendo Unit) was used to measure peak and average velocity and power.
The results showed that average concentric barbell velocity during the back squat 1 RM did not significantly relate with any anthropometric, performance or training experience variables. In contrast, peak concentric barbell velocity during the back squat 1 RM was significantly related with 36.6 m sprint speed (r = -0.612). However, relative strength (1RM squat / body mass) (r = -0.720) and relative peak power during the squat (r = -0.779) were both stronger predictors of 36.6 m sprinting speed than average or peak concentric velocity markers. Therefore, coaches may be able to use relative strength or peak relative power during the back squat as a surrogate for speed testing. Moreover, this study might also suggest(and in line with previous research) that improving lower-body relative strength and power will improve sprinting speed.
Fahs, CA. et al. An Analysis of Factors Related to Back Squat Concentric Velocity. Journal of Strength and Conditioning Research. In press.