>>139526
>So do I do like one back and forth lap kicking like crazy then stop rest and go again
Whether or not you do a "lap" is relative. If a "lap" is the appropriate distance for you, that's what you do. You will not be able to tell what an appropriate distance is until you actually start swimming.
>2 hours?
2 hours is too much like a marathon even if stopping and going. Experienced sprinters can get a basic workout done in ~15 minutes. They may take longer because of auxiliary exercises, stretching routines, etc, but the meat of the workout can possibly be condensed to ~10 minutes if well conditioned and ~20 minutes if you need longer rest intervals. There is no hard rule on how long it should take and how long you should rest. I just want to impress upon you the idea that the main work you want to get done is extremely short in duration and is made up for by the intensity given during that time.
In this study, high-intensity training is compared to high-volume training. (~2 hours is high-volume.)
Mangine, Gerald T., et al. The effect of training volume and intensity on improvements in muscular strength and size in resistance‐trained men. Physiological reports 3.8 (2015).
https://dx.doi.org/10.14814%2Fphy2.12472
>It appears that high-intensity resistance training stimulates greater improvements in some measures of strength and hypertrophy in resistance-trained men during a short-term training period.
In this review, they examined the academic literature and concluded many studies were saying fewer repetitions and higher intensity better improves physical performance:
Lesinski, Melanie, Olaf Prieske, and Urs Granacher. Effects and dose–response relationships of resistance training on physical performance in youth athletes: a systematic review and meta-analysis. Br J Sports Med (2016): bjsports-2015.
http://dx.doi.org/10.1136/bjsports-2015-095497
>Dose–response relationships for key training parameters indicate that youth coaches should primarily implement resistance training programmes with fewer repetitions and higher intensities to improve physical performance measures of youth athletes.
This study lends support to the idea that short workouts are extremely effective. You just have to actually do it and give maximum effort during that short time:
Gillen, Jenna B., et al. Twelve weeks of sprint interval training improves indices of cardiometabolic health similar to traditional endurance training despite a five-fold lower exercise volume and time commitment. PloS one 11.4 (2016): e0154075.
https://doi.org/10.1371/journal.pone.0154075
>We investigated whether sprint interval training (SIT) was a time-efficient exercise strategy to improve insulin sensitivity and other indices of cardiometabolic health to the same extent as traditional moderate-intensity continuous training (MICT). SIT involved 1 minute of intense exercise within a 10-minute time commitment, whereas MICT involved 50 minutes of continuous exercise per session.
…
>Twelve weeks of brief intense interval exercise improved indices of cardiometabolic health to the same extent as traditional endurance training in sedentary men, despite a five-fold lower exercise volume and time commitment.
Basically, the scientific evidence keeps showing all you need to do is get in there, get it done, and don't torture yourself for hours. You may be tempted to think such an "easy" workout being ideal is too good to be true, but the reality is if you workout for a long time you end up not giving your all so you have enough energy for later sets and exercises.
>Since a pool is 50 meters would the equivalent to running 100 meters be one lap?
I wouldn't know if they are directly comparable, and I don't have enough experience swimming to know what distance is comparable to sprinting. However, if we look to the Olympics for guidance, we find the first freestyle competition is "only" 50 meters long and the next up is 100 meters:
https://en.wikipedia.org/wiki/Freestyle_swimming#Competitions
You may find an even shorter difference is appropriate for you. You have to go by how your body feels. You won't know until you start practicing.