[sg516]

i have noticed that i can't do a lap without my heart rate going up to around 170 bpm. my normal resting rate is around the low to mid 50s. anyway, i have tried looking at my technique and thought maybe i am trying too hard or something but even when i go as slowly and relaxed as i am able (without sinking) it still gets up to the 160s. i am currently doing around 18 strokes per length. is that too many? or is this just one of those things that takes time to 'get into swimming shape'? bc i am getting really tired after 15-20 mintues of continuous swim and its starting to worry me that its not getting easier after 6 weeks of swimming three times (an hour at a time) per week.