I've swum for several decades. It's a good form of cardiovascular training. It's also very much a skill sport that's difficult to pick up in later life -- your entire workout distance is a small portion of my warm-up routine (workouts run 3k - 6k meters).
The specific part of the article you want to pay attention to is the training goal matrix (http://archive.mensjournal.com/wp-content/uploads/picture-21...). Swimming does not load your muscles at 40-60% of your maximum. For an utterly untrained individual you'll see some development as the result of doing virtually anything, however that progress will max out very quickly.
Any serious competitive swimmer (national / international / Olympic level) is doing a considerable amount of strength training in addition to their pool work. The same goes for athletes in any other field. While there may be adaptations to limit total mass gains for some (long-distance marathoners and cyclists tend to have low bodyweights), there absolutely is strength training.
If you want to gain muscle, lift. If you want to get better at swimming, invest in a stroke clinic and join a masters team.
I agree: swimming will make you more fit, and works great as general aerobic or anaerobic exercise, but won't necessarily build up muscles beyond a reasonable baseline. However, I'd argue that it works far better than walking or running if you want general calorie burning.
On a different note, though: swimming works very well for building lung capacity, which cross-trains very well with other exercises.
I can attest to the final point. I had to give up running for a month to heal from shin splints and I started swimming and biking to train in the meantime. My previous 5k personal best was 24:00 and when I ran it again after that month of swimming/biking I ran it in 21:52 with relative ease. I attribute it to the swimming which kicked my ass.
I would say it fits with point number four in the article. I found swimming especially good for avoiding normal "office injuries" in the back and hips. I also think it's great mental training as most of the difference for a novice to go from say 10% to 60% in swimming ability is just relaxing and "finding" decent technique.
Strengthening your back and hips, with posterior-chain exercises (squats, deadlifts, chin-ups, rows, kettlebell swings) will do a lot more for back/hip issues than swimming will.
Though swimming does give you a modest amount of lats and trunk stimulus.
You increase the support in a system by strengthing it, not loosening it.
You may want to address imbalances (look up "upper crossed syndrome") by strengthening parts of the system in opposition to those which are overstimulated.
Generally, there's not a whole lot of increase in flexibility you can accomplish by casual stretching, and excess flexibility can be a problem -- pregnant women experience a loosening of tendons and ligaments (it helps in moving the baby through the birth canal) which can present problems in strength training.
Kettlebell swings are most decidedly low-impact training.
Many long distance runner do not lift at all, but there are so many schools of long distance running what actually works still seems like vodoo (at the top level).
I've swum for several decades. It's a good form of cardiovascular training. It's also very much a skill sport that's difficult to pick up in later life -- your entire workout distance is a small portion of my warm-up routine (workouts run 3k - 6k meters).
The specific part of the article you want to pay attention to is the training goal matrix (http://archive.mensjournal.com/wp-content/uploads/picture-21...). Swimming does not load your muscles at 40-60% of your maximum. For an utterly untrained individual you'll see some development as the result of doing virtually anything, however that progress will max out very quickly.
Any serious competitive swimmer (national / international / Olympic level) is doing a considerable amount of strength training in addition to their pool work. The same goes for athletes in any other field. While there may be adaptations to limit total mass gains for some (long-distance marathoners and cyclists tend to have low bodyweights), there absolutely is strength training.
If you want to gain muscle, lift. If you want to get better at swimming, invest in a stroke clinic and join a masters team.