Repetition velocity during the leg and chest press in older adults: influence of starting execution technique.

Background: Effectively implementing velocity-monitored resistance training (RT) requires selecting appropriate methodologies, particularly in older adults. The current study compares the differences in repetition velocity patterns with two different starting execution techniques - eccentric-concentric vs. concentric-only - during RT sets in the leg press (LP) and chest press (CP) in older adults.

Methods: Eighteen participants (67% female; 79 ± 10 years) underwent a 6-week intervention, with the first two weeks dedicated to familiarization and load-velocity profiling. From weeks 3 to 6, participants completed two weekly RT sessions, performing two sets of ten repetitions at 40, 50, 60, and 70% of their one-repetition maximum (1RM), only differing in the starting execution techniques.

Results: The eccentric-concentric technique resulted in higher mean velocity values during the first repetition compared to the concentric-only technique across all relative loads in the LP (average difference: 0.09 ± 0.07 m·s^- 1; p < 0.001; g = 0.84) and CP (average difference: 0.07 ± 0.06 m·s^- 1; p < 0.001; g = 0.70). No differences were found between execution techniques in the fastest repetition of the set (all p > 0.05) and the mean velocity of almost all subsequent repetitions throughout the set. The pattern of repetition velocity was more stable with the eccentric-concentric technique (R²: 0.78-0.97) than with the concentric-only technique (R²: 0.01-0.52). The fastest repetition typically occurred in the second repetition (67.5%) under the concentric-only technique, but in the first repetition (42%) under the eccentric-concentric technique.

Conclusions: These findings indicate that the initial execution technique adopted in resistance machines significantly impacts the mean velocity of the first repetition among older adults, with higher velocities reached using the eccentric-concentric technique. Therefore, velocity-based RT protocols for older adults should account for starting execution techniques in machine exercises to optimize load monitoring and training prescription effectiveness.