(25) THE EFFECT OF HIGH- VS. LOW-VELOCITY RESISTANCE TRAINING ON MOVEMENT SPEED, MAXIMAL STRENGTH, AND THE LOAD-VELOCITY RELATIONSHIP IN OLDER ADULTS

Purpose: The purpose of this study was to examine the effect of a high- vs. low-velocity lower body resistance training (RT) program on concentric movement speed, muscle strength, and the associated load-velocity (LV) relationship in older adults (OA).

Methods: Nineteen OA volunteered to complete an 8-week RT program (2 x per week) and were randomly assigned to a high- (HV; n=10; age=70±6 y) or a low-velocity RT group (LV; n=9; age=74±7 y). Movement speed for each training and testing repetition was assessed using a linear position transducer during the concentric phase of the belt squat movement. Subjects in the HV and LV were required to move at a mean velocity above 0.7m/s and between 0.25-0.3 m/s, respectively. Load was adjusted to ensure movement speed was within appropriate ranges. Participants were provided velocity biofeedback of their concentric movement speed and encouraged to move the load as quickly as possible. Maximal strength was assessed before (PRE), 4-week (MID), and after (POST) the 8-week exercise intervention by increasing the load by 20% increments of the participant’s body weight (BW) until they reached their one repetition maximum (1RM). Both the absolute (ABS_1RM) and relative 1RM (REL_1RM; 1RM/ BW) were recorded. Maximal movement speed (MMS) was defined as the highest mean velocity achieved when lifting the empty rack. A linear regression equation was developed using the mean velocity and relative load (kg/BW) at each incremental step to provide a LV_REL slope. The  LV area under the curve (LV_AUC) was calculated from the LV_REL slope using the trapezoidal method. Separate 2 (condition) × 3 (time) repeated measures ANOVAs were run to examine differences between groups in ABS_1RM, REL_1RM, MMS, LV_REL slope, and LV_AUC. An independent t-test was used to examine the difference between average total exercise volume (repetitions/load) between groups and Hedges’ g was used to estimate effect size.

Results: There were no significant interactions for ABS_1RM, REL_1RM, MMS, LV_REL slope, or LV_AUC. However, a significant (p ≤ 0.05) main effect for time was observed for ABS_1RM (p=0.002, PRE=142.67±27.17kg vs. POST=186.28±41.80kg, Hedges’ g=-2.46), REL_1RM (p≤0.001, PRE=2.01±0.22kg/BW vs. POST=2.67±0.47kg/BW, Hedges’ g=-3.57), and LV_AUC (PRE=0.40±0.24 kg/BW·m/s vs. MID=0.65±0.30 kg/BW·m/s, p=0.03, Hedges’ g=-1.83; PRE=0.40±0.24 kg/BW·m/s vs. POST=0.78±0.32 kg/BW·m/s, p≤0.001, Hedges’ g=-2.67). There was no significant difference in average total exercise volume between groups (HV=47,490±10,888vs. LV=43,721±14552, p=0.26, Hedges’ g=0.60).

Conclusions: These data suggest that when total exercise volume is matched, both HV and LV RT training result in significant improvements in strength and movement speed in OA. The significant  increases observed in LV_AUC at MID and POST also suggest that LV_AUC may be a better indicator than LV_REL slope for monitoring  training adaptations over time.  PRACTICAL APPLICATIONS: Both HV and LV resistance training programs are effective for increasing strength and movement speed in OA. Therefore, practitioners and strength and conditioning professionals can use these data to guide training prescription for their older clients.

Acknowledgements: This study was funded by the NSCA Young Investigator Grant.