Have recently started using the rowing machines mid week at my local leisure centre to supplement an hour of fin work (half soft rubber bifins, half waterway monofin) each Sat & Sun - and am noticing an improvement already.
All I know about interval training comes from the downloadable training manual provided free by the rowing machine manufacturer - see
www.concept2.com - or ~.co.uk in the uk. Around 250 pages covering so many relevant topics. Section 3: Physiology is a good place to start, also Nutrition and Weight Management (Section 8), etc, etc. It`s a gem.
Anaerobic may NOT be what you need - that`s aimed at the 10 sec sprinter who`s muscles are burning energy faster that oxygen can be supplied to them. Our muscles are working in an aerobic regime, slowly depleting the oxygen stored in the blood. Our lungs are in apnea but our muscles are not.
Nice thing about the rowing machine is that the risk of drowning is pretty small, and by using a heart monitor it`s easy to keep the heartrate in the desired band.
I`ve gone for - UT1 row warm-up (HR 120-140), a set of 15sec streches, TR row (4 sets of alternating rows @HR 150-166, and rests back to HR 120-ish), machines (working the abdominal and lower back muscles), AT row (2 sets alternating HR 140-149/120-ish), UT2 row warm-down (HR 100-120), and final 45sec each streches. Around 75 mins for the whole session. These reflect my max heartrate of somewhere in the 170-175 range, manual shows how to set them to suit your own.
Please don`t even contemplate just copying the above - it`s the result of applying my possibly twisted logic to what I think the manual says. The TR session may not be at all suitable, but I wanted to teach my body to recover more quickly in between the lots of fastish 25 m apneas I do at the weekend. Dropping it and doubling the AT reps may be more applicable to freediving.
Havn`t tried holding my breath on the rowing machine to imitate the apnea walk. Not far to fall, but don`t think blacking out would do much for my reputation.