ABSTRACT
Sport performance coaches use a range of modalities to apply a horizontal force (Fh) to athletes during resisted sprint training (RST). These modalities include parachutes, weighted vests, pulley devices, motored tethered devices, and, most notably, weighted sleds. Despite the widespread use of these devices, the resistance forces of the pulley devices have not been evaluated for reliability and accuracy. Therefore, the primary aim of this study is to quantify the Fh of a commercially available pulley device (EXER-GENIE®) and determine how resistance force is related to the load settings on the device. The secondary aim is to identify the differences in the Fh values between three EXER-GENIE® devices that use 36â m and 60â m ropes. The Fh values in the Newtons (N) of the three EXER-GENIE® devices were analyzed using a motorized winch, a lead acid battery, and an S-beam load cell. Four 10â s winch-driven trials were performed using 15 different EXER-GENIE® loads, ranging from 0.028â kg to 3.628â kg, employing two different 36â m devices and one 60â m device. The mean ± standard deviation for Fh was reported across the four trials for each load setting. All devices produced similar Fh values across lighter load settings (loads ≤0.141â kg). However, at heavier loads (loads ≥0.226â kg), the 60â m device had Fh values 50-85â N greater than those of the 36â m device. The coefficient of variation across the four trials was extremely high at light loads but sharply decreased to <10% at heavy loads. Absolute reliability was high for each device [intraclass correlation coefficient (ICC) = 0.99]. A regression analysis for Fh values and EXER-GENIE® load indicated a strong positive relationship between load and Fh values across all devices (R2 = 0.96-0.99). Caution should be exercised when using identical loads on the different-length pulley devices, as the 60â m device produced greater Fh values than the 36â m devices at load settings higher than 0.226â kg. These results can provide coaches and practitioners with a better understanding of the magnitude of resistance that is applied when prescribing EXER-GENIE® devices for higher training loads.