Kinematic, kinetic, and blood lactate profiles of continuous and intraset rest loading schemes

The purpose of this study was to investigate and compare the acute kinematic, kinetic, and blood lactate responses to continuous and intraset rest loading schemes that differed in terms of rest frequency but not total rest duration. Nine male subjects performed an isoinertial bench press task (6 repetition maximum load) with a continuous, an intraset rest equated by total rest time, volume, and load (ISRV), and an intraset rest equated by total rest time and load (ISRR) loading scheme. The scheme order was assigned in a block-randomized order with a minimum of 48 hours of recovery between testing sessions. Attached to the bar of the Smith machine was a linear position transducer that measured vertical displacement with an accuracy of 0.01 cm. Displacement data was sampled at 1,000 Hz and collected by a laptop computer running custom-built data acquisition software. Finger prick blood lactate samples were taken from the nondominant hand before exercise, immediately after exercise, and 5, 15 and 30 minutes after exercise. Blood glucose samples were taken before exercise only. It was observed that manipulating the rest period, by increasing the frequency but decreasing the length of each rest period, did not significantly influence the kinematics and kinetics associated with resistance training, but did have an effect on the postexercise blood lactate response when the load, rest duration, and training volume were equated (ISRV). This finding may be of practical significance if fatigue is important in strength development or conversely if power training requires minimal fatigue. It was also observed that increasing the frequency of the rest period enabled the subjects to perform a greater number of repetitions (ISRR), resulting in significantly greater kinematics, kinetics, and blood lactate accumulation.