The professor I sent this question to thought my original comment was reasonable but was not sure
about overall metabolism (e.g. bmr). I could not find anything specific on metabolism and beta
blockers, but thought you would find this abstract interesting. I would guess that if you cannot
achieve the same yardage in the time it used to take you, then to expend the same amount of calories
that you used to during your swim, you would have to add the extra time to reach that yardage. But,
I will follow this thread because someone may know something that I can learn along with you.
Marianne
Eur J Cardiovasc Prev Rehabil. 2003 Aug;10(4):296-301.
Influence of beta-blocker use on percentage of target heart rate exercise prescription.
Wonisch M, Hofmann P, Fruhwald FM, Kraxner W, Hodl R, Pokan R, Klein W.
Department of Internal Medicine, Karl-Franzens University Hospital, Graz, Austria. manfred.wonisch@uni-
graz.at
BACKGROUND: Exercise is recommended for cardiac patients irrespective of beta-blockers. Percentages
of maximal heart rate (%HRmax) and heart rate reserve (%HRR) are widely used to determine training
intensities. The purpose of this study was to investigate the influence of chronic cardioselective
beta blockade on the %HRmax and %HRR model. METHODS: Ten healthy male subjects randomly received
oral placebo or beta-blocker bisoprolol (5 mg/day) for 2 weeks using a double-blind, crossover
design. In the second week, the subjects performed a cardiopulmonary exercise test until exhaustion
to determine the aerobic (AeT) and anaerobic (AnT) threshold. RESULTS: No significant differences
were found for absolute and relative values of oxygen consumption, power output and ratings of
perceived exertion at AeT, AnT and maximum workload. Mean HR was significantly (P<0.05) lower at
rest (-15 +/- 5 bpm), AeT (-19 +/- 8 bpm), AnT (-22 +/- 10 bpm) and maximal workload (-19 +/- 11
bpm) with bisoprolol compared to placebo. Percentage of maximal heart rate (%HRmax) was
significantly (P<0.05 ) reduced at rest (43 versus 39%), AeT (64 versus 60%) and AnT (86 versus
82%), a trend for a reduction was found for %HRR at AnT (75 versus 71%, P=0.07). CONCLUSIONS:
Exercise prescription using %HRmax or %HRR methods are of limited accuracy for patients taking beta-
blockers. Although %HRmax and %HRR are easy to determine and therefore attractive, we suggest that
the most precise exercise prescription would depend on AeT and AnT. Percentages of maximal oxygen
consumption or maximal workload or ratings of perceived exertion may be suggested as a substitute.
Alternatively, upper limits for %HRmax and %HRR should be lower for patients taking beta-blockers.
"MSEagan" <[email hidden]> wrote in message news:FaWTb.210404$I06.2332310@attbi_s01...
Quoted message said:This is a good question. My guess is that if you are able to cover the
same
Quoted message said:distance that you were before, then caloric expenditure is the same. But,
I
Quoted message said:sent this to one who is more expert in this than I am, and if she has any answers, I will post
them. Marianne
"Chuck Wyatt" <[email hidden]> wrote in message
"]news:[email hidden]...
Quoted message said:I'm taking a beta blocker to lower my typical resting HR from between 90-100 to between 70-80,
so lowering it about 20 points. As expected, my swimming workout rate has dropped from around
150-160 to 130-ish.
What is the effect on calorie expense? Sure feels like I'm working just as hard but performing
less well.
I don't get asthma while swimming, but wonder if there are any other potential risks?
thanks,
Chuck