I have the very great pleasure to live and work in a literal swimming epicenter. Madison, WI is home to the All City League that includes 13 neighborhood swim teams that all come together annually for the All City Swimming and Diving Championship at the end of summer. This happens to be one of the (if not the single) largest outdoor amateur championship athletic events in the country. The Tri-County Conference is another summer swimming league that also culminates with a championship format meet at the end of the summer. These age-group summer swimming leagues help to foster a love of swimming in young swimmers that have bolstered at least 10 USA LSC (Local Swimming Committees) in and around the Madison area that have gone on to produce world class swimmers.
My swimmer clients often tell me that there is not a focus on strengthening during their club seasons. Many of them report doing body weight core work, but it seems that actual time spent in the weight room is lacking.
Don't get me wrong, the core strength gained from dry land workouts is vital to swimming - a tight core is essential for maintaining a good streamlined position in the water, and as a means of transferring power and force via rotation from a swimmers hips to their shoulders.
However, as a PT, many of the injuries that swimmer clients deal with are related to inadequate strength to support the high level of repetitive work that swimmers do day in and day out. While there are many factors (including by not limited to actual swimming stroke technique) that can contribute to any one individual's pain, it is undeniable that having a strength imbalance can set a swimmer up for trouble. Mike Tufo, a Strength and Conditioning coach at Rutgers University said that 'The primary reason for strength training athletes is injury prevention. Stronger bodies are less susceptible to injury especially when weak areas are targeted for a specific sport.'
While it's true that lifting (especially heavier weights) can cause soreness (lifting does break down muscles in the process of building them up) and maybe an initial decrease in early season speed, as the body adapts to the increased loads placed on it by a well-designed lifting program the soreness will dissipate and athletes will start to see the benefits of a regular training program.
It is important for athletes to be coached appropriately while in the weight room. Likewise, it is essential for the strength coach to have an understanding of the demands that swimming requires, thus good communication between the swim coach and the strength coach is essential. It is also important for swimmers to have good foundational strength and movement patterns before hitting weights, so some developmental dry land training, especially for younger athletes is by far more important than lifting in the early stages.
The idea that lifting can cause injuries is, frankly, old news. There are countless studies that have been done that show the benefits of resistance training, and demonstrate that lifting is not inherently 'dangerous' if the athlete is coached well and has been appropriately progressed.
In conclusion, if you or your swimmer isn't currently lifting at least a couple days a week, find what the bottleneck is; time, resources, or your coaches limitations in knowledge of how to program. There are multiple resources available, either as a team or for individuals. Set yourself up for faster swims, more power and fewer injuries by finding yourself a strength coach!