Acute and Short-Term Response to Different Loading Conditions During Resisted Sprint Training

Effects of resisted sled training on sprint performance in team sports. A systematic review and meta-analysis

OBJECTIVE

This systematic review and meta-analysis aimed to examine the effects of resistance sled training (RST) on sprint performance in team sport athletes.

METHODS

A systematic search was conducted in the electronic databases MEDLINE, Sportdiscus, Scopus and Web of Science from inception until October 2023. Randomized or non-randomized controlled clinical trials that included collective field sports athletes who were trained with sled drag were included to evaluate the effectiveness of the training on performance in speed tests. Independent reviewer selected the studies with www.rayyan.ai, extracted the data, performed the risk-of-bias assessment, and methodological quality. The sprint time at distances of 5, 10 and 20 m were included for the meta-analysis. A random-effects model, standardized mean difference, and standard deviation were used for meta-analysis.

RESULTS

Fourteen studies involving 344 participants were selected (overall risk: high risk; methodological quality: moderate quality). Meta-analysis revealed statistically significant effects in favor of RST on 5 m (SMD = -0.87; 95% CI = -1.58 to -0.16; p = 0.02) and 10 m (SMD = -0.40; 95% CI = -0.78 to -0.03; p = 0.04). However, there are no significant effects on 20 m (SMD = -0.34; 95% CI = -0.73 to 0.06 p = 0.1).

CONCLUSION

These results indicate that RST improves performance mainly in the short distance, suggesting that RST is a viable training method to improve athletic performance in team sports.

Speed Training Practices of Brazilian Olympic Sprint and Jump Coaches: Toward a Deeper Understanding of Their Choices and Insights (Part II)

This is the second article in a three-article collection regarding the plyometric, speed, and resistance training practices of Brazilian Olympic sprint and jump coaches. Here, we list and describe six out of the ten speed training methods most commonly employed by these experts to enhance the sprinting capabilities of their athletes. Maximum speed sprinting, form running, resisted sprinting, overspeed running, uphill and downhill running, and sport-specific movement methods are critically examined with reference to their potential application in different sport contexts. In an era when sprint speed is of critical importance across numerous sports, practitioners can employ the methods outlined here to design efficient training programs for their athletes.

Resisted Sled Sprint Kinematics: The Acute Effect of Load and Sporting Population

In this study, we assessed the acute kinematic effects of different sled load conditions (unloaded and at 10%, 20%, 30% decrement from maximum velocity (Vdec)) in different sporting populations. It is well-known that an athlete’s kinematics change with increasing sled load. However, to our knowledge, the relationship between the different loads in resisted sled sprinting (RSS) and kinematic characteristics is unknown. Thirty-three athletes (sprinters n = 10; team sport athletes n = 23) performed a familiarization session (day 1), and 12 sprints at different loads (day 2) over a distance of 40 m. Sprint time and average velocity were measured. Sagittal-plane high-speed video data was recorded for early acceleration and maximum velocity phase and joint angles computed. Loading introduced significant changes to hip, knee, ankle, and trunk angle for touch-down and toe-off for the acceleration and maximum velocity phase (p < 0.05). Knee, hip, and ankle angles became more flexed with increasing load for all groups and trunk lean increased linearly with increasing loading conditions. The results of this study provide coaches with important information that may influence how RSS is employed as a training tool to improve sprint performance for acceleration and maximal velocity running and that prescription may not change based on sporting population, as there were only minimal differences observed between groups. The trunk lean increase was related to the heavy loads and appeared to prevent athletes to reach mechanics that were truly reflective of maximum velocity sprinting. Lighter loads seem to be more adequate to not provoke changes in maxV kinematics. However, heavy loading extended the distance over which it is possible to train acceleration.

Chronic electrical stimulation reduces reliance on anaerobic metabolism in locust jumping muscle

Chronic electrical stimulation (CES) is a well-documented method for changing mammalian muscle from more fast-twitch to slow-twitch metabolic and contractile profiles. Although both mammalian and insect muscles have many similar anatomical and physiological properties, it is unknown if CES produces similar muscle plasticity changes in insects. To test this idea, we separated Schistocerca americana grasshoppers into two groups (n = 37 to 47): one that was subjected to CES for 180 min each day for five consecutive days and one group that was not. Each group was then electrically stimulated for a single time period (0, 5, 30, 60, or 180 min) before measuring jumping muscle lactate, a characteristic of fast-twitch type fibers. At each time point, CES led to a significantly reduced jumping muscle lactate concentration. Based on similar short-term CES mammalian studies, the reduction in lactate production was most likely due to a reduced reliance on anaerobic metabolism. Thus, longer stimulation periods should result in greater aerobic enzymatic activities, altered myosin ATPase, and shift fiber types. This is the first study to use electrical stimulation to explore insect muscle plasticity and our results show that grasshopper jumping muscle responds similarly to mammalian muscle.