Fifty Plus (50+) - Betablockers and Training
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Does anyone know if beta blockers will reduce the benefits of exercise, specifically improving the strength and efficiency of the heart. What would be the differance of the training effect on the heart if one was exercising at 70% of maximum HR on a beta blocker lets say at 130 BPM, and the same person exercising at the same 70% of maximum HR with no beta blocker at 145 BPM?
I am not a cardiologist-just an engineer who has slept in a Holiday Inn.
Having said that, I'd be surprised if the medication made a signficant difference between the two situations in terms of overall benefit from cardio improvements from exercising at the 70% level. I could some impact if the beta blockers prohibited allowing the heart rate to get above a 70% level. I would think that the person without the Beta Blocker might be able to have a higher power output since he could probably raise his HR higher-but in terms of the benefits of exercise, both situations should lead to excellent improvements in both strength and efficiency if the exercise is done with reasonableness.
However one area that could make a difference is with the "interval" training-where the HR is raised to above 80% for a period and then allowed to drop back to 60-70%. The non-beta blocker candidate might be able to see a little more aerobic improvement over time due to those benefits derived from that training.
A friend of mine went on Beta Blockers and found his "top end" and overall output was decreased after going on it. He was not satisfied with being in that situation and has changed medications.
Beta blockers reduce the intrinsic cardiac response to sympathetic stimuli to heart rate and to a lesser degree the forcefulness of muscle pumping. Net result is a slower heart rate at rest and a decreased ability of the heart to beat rapidly. Beta blocker dose range is about 6-1 or 8-1 range (eg 25mg to 200mg). At the bottom end 25mg or equivalent level (dose equivalents can be tricky but most commonly used beta blockers are in the 10-100mg dose range) the effect will be fairly small and tolerable except for those whose top 5-10% is used frequently. Most of us are happy exerting 60-80% of our max output and don't want to go above 80% because it makes us feel bad, and your tongue gets dirt off the front tire. As the dose goes higher the damping down of the top end of cardiac output begins to encroach on the 80% level and can be a problem to more ordinary athletes. Since so many other meds are available it should be easy, for most uses, to stay at the low end doses and use something else to get the BP down, or fend off the next MI, migraine, palpitation attack or whatever. Bottom line is that your training will be compromised to some degree by beta blockers and % HR is less useful as a sign of training intensity, or you will have to go to some trouble to recalibrate your response to exercise to achieve your training goals.
02-25-06, 02:06 AM
I was put on 20mg of Atenolol after the bypass and this did effect the Heart rate.
Before the Bypass, I could regularly get my HR up to 170. Whilst on the Atenolol I could not get my HR above 130- No matter how much effort I put in. In my experience Beta- blockers will slow the HR and they will not allow you to get it up to your normal working level.
Now off them but I ride with my HR between 140 and 150 and get up to 165 for short bursts when I have to. At 140 I am comfortable and 165 it is getting hard.
On the beta blockers I could not get my HR above 130 and that was breathing hard and tired legs. In fact- I could not keep the HR at 130- It was the equivalent of my normal 165. Every time I hit a hill, or long slope, I could not keep the effort in and slowed to 110. That 110 was the equivalent of my now 140.
When you exercise- you need oxygen in the blood to be pumped round to keep the muscles working. If you cannot get the blood pumping round as quick- then you lose out on oxygen which leads to tired muscles, hard breathing and feeling knackered.
02-25-06, 04:23 AM
I'm not a cardiologist either, but did go to med school.
Almost all beta blockers in current use are so called 'cardioselective' in that they do not affect peripheral vascular resistance. Their effect of inhibiting heart rate increase reduces ventricular filling and therefore ejection volume. The resulting reduction in exercise tolerance is well known and appears in the manufacturers data sheets for all thhe available ones.
Non selective BBs (eg propranolol, oxprenolol) also reduce exercise tolerance. Their peripheral effects can benefit non cardiascular conditions such as migraine, anxiety and sweating.
I had a terrible time on a BB (bisoprolol). Exhausted and barely able to get up stairs.(previously a reasonably fit 48 yr old). In fact my 'hypertension' responded to other measures and I was able to come off it. The effect was incredible!
I wonder why you are taking it. Apart from critical indications such as cardiac arrythmia, BB's are mostly used as part of a combination drug regime for hypertension. The BB component was thought to be the gold standard of prevention - stroke, heart attack etc) but most recent trials have shown this to be untrue. There are therefore effective alternatives to BB's which will definitely not reduce exercise tol. - of course, they will have other and different side effects. The same applies to the prevention of angina for which there are again non-BB alternatives.
Stopping BB's abruptly can cause dangerous rebound effects so you should get appropriate medical advice and supervision.
I wonder why I am taking them too, thats why I asked the question. Thanks all for the response, I have my annual appointment with my cardiologist next week and I am going to question him on why I should be taking this drug, Atenolol 25 mg. once a day. I am 50 and had a double bypass also in 1999. Currently I cycle 25 km/day 5 days a week indoors, in the cycling season I do 40-50 km/day. My blood pressure is never higher than 120/80, usually 100/60 sometimes lower, my resting heart rate is as low as 50. I had a cardiovascular fitness test last March wich resulted with a VO2 max of 46 ml/kg/min., I was on the beta blocker when I did the test and reached a maximum HR of 166. I questioned my GP about why I am on a betablocker he mentioned what you had said, abarkley, that betablockers were the gold standard for prevention of a MI, he suggested that I talk to my cardiologist though about this. One other thing I don't understand about the Betabockers if you are on the drug, how can you lets say run in mile in 10 minutes with a average HR of 135 BPM, then run the same mile in 10 minutes when off the Betablocker and have an average HR of 155 BPM. What does the BB do to your system that allows you do do the same intensity of work yet at a lower HR?
02-25-06, 04:20 PM
One other thing I don't understand about the Betabockers if you are on the drug, how can you lets say run in mile in 10 minutes with a average HR of 135 BPM, then run the same mile in 10 minutes when off the Betablocker and have an average HR of 155 BPM. What does the BB do to your system that allows you do do the same intensity of work yet at a lower HR?
I never bothered to time myself, but I know I was slower in comparison to my thoughtful riding partners who slowed down for me. They never allowed me to do the same intensity of work as when I was off them and this is borne out by my neighbour that was on BB's for high blood pressure at the gym. The BB's did not allow either of us to do an intense workout.
One thing about BB's is to come of them gradually. Do not suddenly stop taking them. The way I managed to get a beter workout was to take a pill the night before a ride- instead of the morning of. Then I took it as soon as the ride was over.
02-25-06, 07:29 PM
See my post from a previous thread on beta blockers http://www.bikeforums.net/showthread.php?p=2147250#post2147250
An update to this. Swimming is now up to 4Km and going for a 5Km today. Going to try the ocean swims soon, when I am comfortable with the 5K pool swims - every morning at 6AM there are numerous group swims here, just like group rides. You pick a group doing your speed and swim with them - out to sea couple of hundred meters and then along the coast for 5K's or so (think of sharks like cars - better odds in a group!!!).
Finally completely off the beta-blocker. Don't underestimate how difficult this can be - well for me anyway, but I don't think I am alone. It's worth it. I couldn't get past 2Km swim on the blockers and had to stop for a rest every 200m. Off the blockers, 4Km straight with no rests is a breeze. Riding is the same. Continuous 30kph @ 90rpm & 140bpm on the flat on blockers, 36 to 38kph at 100rpm & 165bpm off the blockers. HRmax has gone from 160 (approx) blocked to 181 (best yet) unblocked.
I hope this post helps someone - at least to know what to expect and what the rewards may be. Just DO NOT go it alone - get you GP or Cardio on side and get monitored. Don't ask for permission - just help.
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