The pre-training warm-up serves a variety of important purposes. For example, the increase in body temperature and purposeful movement through full ranges of motion prepare the body for intense activity that lower injury risk. With the appropriate warm-up protocol, we can even prime the nervous system to transiently increase performance. We’ve seen this numerous times with post-activation potentiation leading to faster sprinting and higher jumping. However, using post-activation potentiation to facilitate increases in performance during strength exercises such as squatting or pressing may lead to greater neuromuscular adaptations that may transfer to on-field performance. However, the majority of research in this area has focused primarily on jumping and sprinting outcomes with strength being less studied.
A new study published ahead of print in the European Journal of Sport Sciences evaluated the influence of chain-loaded resistance during squat warm-ups on subsequent free-weight 1RM back squat strength compared with traditional free-weight warm-ups. Sixteen recreationally trained males were recruited for this study and participated in a randomized cross-over trial where they performed either the experimental protocol (warming up with 85% of 1RM with chains) or the control condition (warming up with 85% of 1RM without chains). The use of chains overloads the end-range of motion and reduces the load at the sticking point, allowing the lifter to accelerate through to full extension. After 5-minutes of passive rest following each warm-up protocol, 1RM back squat strength was evaluated and compared between groups. Electromyographic activity of the knee extensors and flexors were recorded during 1RM attempts.
The results showed that 1RM squat values on average were significantly greater (6.2%) following the chain-loaded warm-up than following a traditional warm-up. In addition, mean eccentric knee extensor EMG activity was on average 32% greater following the chain-loaded warm-up compared with the traditional free-weight warm-up. No mechanical differences in the squat were observed (i.e., peak knee flexion angle, concentric angular velocity, etc.) Thus, the authors conclude that chain-loaded warm-ups provide real increases in 1RM strength (since squat mechanics remained unchanged). Incorporating chains during warm-up may therefore be useful for athletes looking to enhance strength.
Mina, M. A., Blazevich, A. J., Giakas, G., Seitz, L. B., & Kay, A. D. (2016). Chain-loaded variable resistance warm-up improves free-weight maximal back squat performance. European Journal of Sport Science, 1-8.