How does your swim time translate across pool formats?

Close enough for seeding and planning, but no more than that. World Aquatics doesn't publish course conversion factors; the tables in use come from bodies such as USA Swimming and the NCAA, and every one of them gives an average across swimmers rather than a personal figure. Anybody with an exceptionally strong underwater kick gains more from short course than the average, which makes their SCM or SCY times look disproportionately fast next to their LCM times.

Long course metres, meaning 50-metre pools, and nothing else. That creates a problem specific to American swimmers, because US high school and NCAA competition runs in short course yards with 25-yard pools, so age-group and collegiate swimmers train and race in SCY and then have to convert to LCM for Olympic Trials and international meets. Australia, the UK and most of continental Europe run their major competitions in LCM from the start.

SCM is a 25-metre pool and SCY is a 25-yard pool, which is shorter, so an SCY race packs in even more walls than an SCM race of the same nominal distance. That shows up directly in the conversion factors: SCM to LCM adds roughly 1 to 2% to a time, while SCY to LCM adds 6 to 10%. An SCY personal best therefore reads much faster than it is to anyone used to metres. US high school and NCAA competition runs in SCY, which is why the gap matters most to American swimmers. Source: USA Swimming and NCAA conversion tables; World Aquatics course rules.

Roughly 1% a year after 30, which sounds gentle and compounds hard. A 50-year-old holding 37 ml/kg/min is at the same relative fitness as a 30-year-old at 43. For scale, men aged 20 to 29 average about 43 to 46 ml/kg/min with excellent starting at 51+ on ACSM standards, and women the same age average 36 to 38 with excellent at 44+. Training buys back more than the decline takes: regular aerobic exercise lifts VO2 max by 15 to 20% in previously sedentary people, which is a decade or more of age handed back. Source: ACSM Guidelines for Exercise Testing, Shvartz and Reibold 1990.

Add the seconds you took for one length to the number of strokes it cost you, and that is your SWOLF. Swim 25 metres in 30 seconds taking 20 strokes and you score 50. Lower is better, because the metric balances speed against technique rather than rewarding either on its own. A recreational swimmer typically sits at 55 to 75 per 25m and a competitive one at 30 to 45. Most swim-capable GPS watches work it out for every length without being asked. Source: Garmin swim metrics documentation, SwimSmooth coaching methodology.

They look at both, and the raw LCM time usually carries more weight. A conversion is a population average, so it tells a coach roughly where a recruit sits and nothing about how that particular swimmer got there. Somebody with an exceptionally strong underwater kick banks more from short course than the factors assume, which flatters their SCY times and leaves the converted number optimistic. Seeing an actual long course swim resolves that. Source: USA Swimming and NCAA conversion practice.

Yes, and they have to be. Olympic records are long course metres records, set in 50-metre pools, while the World Short Course Championships run in 25-metre pools and keep their own record list. Mixing the two would be meaningless, given short course hands every swimmer extra walls to push off. American swimmers add a third format to the pile, since high school and NCAA competition uses short course yards, which is why converting to LCM before Olympic Trials is a routine part of the calendar there. Source: World Aquatics competition rules, USA Swimming.

Almost, though the ceiling is lower in the water. Measured during maximal swimming, VO2 max typically comes in 10 to 15% below the running figure, because a horizontal body position reduces venous return. Swim-specific training still produces strong aerobic gains, and cross-training studies find that swimmers who add running push their VO2 max past what swimming alone delivers. For cardiovascular health rather than performance, swimming at moderate to vigorous intensity for 150+ minutes a week meets every major health guideline and cuts cardiovascular disease risk by a comparable margin. Source: McArdle et al., Exercise Physiology; ACSM position stand.