In a world of specificity, sometimes "practice makes perfect" is not always the answer. Through my experience and the experience of others, practicing a given skill seemed to be the "go to" thing to do day in and day out. In basketball, for example, we performed shooting/running drills with little to not weightlifting. It's not rare to see NBA players performing weighted work outs year round (though frequency may vary in-season/off-season). In this article I will discuss the theory behind this specificity, what the research says, and the application this research has on your training program for athletic performance.
After talking with coaches, having been coached by numerous coaches, and evolving my own training ideology, I have came to realize the theory emphasized by coaches who prioritize sport specifics and stay far from weight training. The idea of getting better at a skill is transparent. Every coach knows to get better at something you must practice. What is muddy and not so clear is the realization that other styles of training can carry over to their sport and even help athletes surpass their previous abilities when testing their skills. Why would you taken the time to use weights to improve your ability to run and jump when you can just jump MORE (amount of repetitions and height/distance) in order to improve your abilities? The answer lies within the literature.
It's no surprise that coaches are emphasizing their weight training programs. As more studies are being performed on athletes, more literature is being able to support the use of weight training in athletic training programs. For example, this study supports the notion that by combining high-intensity strength and sprint interval training with their original training program (technique and drills), athletes are able to further improve their athletic performance as long as recovery is accommodated for. Though high-intensity resistance training may be beneficial for off-season athletes, what about in-season? Surely athletes should just focus on skill work during the season, right? Well, according to the research, athletes who do perform this training in-season can benefit from enhanced strength, jumping ability, and repeated sprinting capability, while others not performing in-season lifting can actually experience lowered strength and power. Not only is weight lifting, high intensity strength training, and general resistance training beneficial for athletes, but even in-season athletes should be performing these types of training to improve their athleticism (even prevent regression).
Just because weight lifting is beneficial to athletes for athletic performance, that does not mean coaches should be overwhelming athletes with brutal work outs year-rounds. As a rule of thumb athletes should focus on 75% high-intensity strength training during the off-season with 25% sport specific work, while during in-season focus on 75% sport specific work and 25% high intensity strength training. Both skill mastery and physical attributes should be prioritized during in-season and the off-season. The only change is by how much each is prioritized depending on the season. (Note: These are generalized percentages. All coaches should adjust according to the needs and talents of their athletes.)
Though "practice makes perfect" when it comes to skill mastery, sports are not just about practice. The reality of most sports is that physical abilities also play a huge role. In order to improve athletic performance, athletes can supplement their off-season and in-season training with weight lifting (more specifically high-intensity strength training). Whether you are in-season or off-season, you can perform supplemental training for your sport, the only change would be prioritizing which one the most. By building a bigger, faster, and stronger body, athletes have a greater opportunity to perform to their maximum potential.