###### Abstract  
The purpose of this study was to compare changes in muscle pre-activation and short-latency responses in the lower limbs during drop jumps performed on different common soft and hard surfaces and at various platform heights. The study aimed to collect electromyography data from the rectus femoris, biceps femoris, tibialis anterior, gastrocnemius, and soleus of the dominant leg during drop jumps on sand, turf, polyurethane, and wood surfaces from platform heights of 30, 40, 50, and 60 cm. Muscle pre-activation refers to muscle activity 100 ms before ground contact during a drop jump, while short-latency responses refer to muscle activation occurring 30-60 ms after ground contact. These definitions were used to measure and analyze neuromuscular responses in the lower limb muscles during drop jumps using various surfaces and platform heights. Sand as a ground material and platform heights of 50 and 60 cm significantly enhanced pre-activation and activation in short-latency responses of the lower limb muscles (all \(p<0.01\)). The difficulty of the drop jump task can enhance pre-activation and activation in the latency responses of lower limb muscles. It is recommended that athletes perform drop jumps on sandy surfaces or from platforms higher than 50 cm to induce muscle pre-activation of the lower limbs and to improve muscle activation levels in the latency responses after landing. biomechanics; electromyography; latency response; glyometric training; pre-activation; stretch reflex; stretch-shortening cycle +
Footnote †: journal: Medical  
vertical jumps, sprints, or cuts on unstable surfaces (turf, sand, and laterite, among others), such as uneven turf on soccer, rugby, and baseball fields and the soft mats on which athletes land in gymnastics. Sports performances that occur on unstable surfaces can easily result in non-contact injuries to the lower limbs [12]. Recently, in response to the instability of these surfaces and to simulate movement on specific unstable surfaces, coaches have introduced glyometric training programs on the field (versus in the gym, where they are traditionally performed) with an unstable surface, which has been found to promote the synergistic contraction of agonist and antagonist muscles and improve joint stability, spine stability, unanticipated postural adjustment, and proprioception and neuromuscular control of the lower limbs [13,14]. Previous studies have pointed out that the activation of lower limb muscles during the braking phase of jumping or landing is affected by stretch load. During this phase, the muscles are pre-activated, followed by muscle activation during the stretch reflex, which has been shown to have a great impact on the performance of the SSC [15, 16, 17, 18]. The stretch reflex is a neural response that occurs following the stimulation of muscle spindles, and the short-latency response is the earliest muscle response in the stretch reflex, with a reaction time of approximately 30-60 ms after ground contact [18, 19, 20, 21]. Studies have shown that higher muscle pre-activation levels and short-latency response are associated with increased muscle stiffness in the lower limbs to resist the high impact load at the given landing height and achieve more efficient storage of elastic potential energy upon touching the ground [18]. Previous studies have explored the impact of the differences in material surfaces on sports performance and found that factors such as softness, rebound, cushioning, and power absorption all affect the performance of tasks [12,17,22]. However, none of these studies have examined common material surfaces on sports fields, which is a research gap that the current study aims to fill. The novelty of the current study is that it tests common material surfaces, including sand, turf, polyurethane (PU), and wood, on sports fields in combination with platform heights of 30, 40, 50, and 60 cm for drop jumps.