Weight lifting damages the heart, cardiologist said

Yes, he did really say that. Actually, it was two of them, and they were singing more or less the same song.

But let me step back, so that I can give the whole picture: three weeks ago I had heart surgery, more precisely "Transcatheter ablation for atrial fibrillation". It's not open heart surgery but still not a walk in the park, let me tell you. During the last three years I have been having increasingly frequent episodes of atrial fibrillation so my choice was between medication (with side effects) for the rest of my life and surgery - which has an 80% chance of success. I chose surgery. It's still eary to tell if the atrial fibrillation is cured, only time will tell.

But back to strenght training. After the surgery I asked one of the cardiologists on staff WHEN I would have been able to resume weight lifting (I was doing stronglifts 5x5 up until the operation) and he said that I couldn't, vaguely suggesting that it was not for me. So I asked another cardiologist, who firmly replied: "NEVER!", and then went on telling me that weight lifting may damage the heart, not just MY heart, but ANY heart, and that should be avoided.

That gave me pause. I do not want to blindly accept that answer, but it wouldn't be smart to dismiss such a strong statement, knowing that those cardiologists are surely not incompetent - one of them is on staff in a world renowned heart center.

So I did a little research and found a few articles, but mainly a 2007 statement by the American Heart Association about "Resistance Exercise in Individuals With and Without Cardiovascular Disease".

I'll highlight a few keypoints below but I'd like to know if anyone has more data and/or science based contributions on this topic, that I think it's of paramount importance for everyone who strenght train, with or without heart complications.

A side note: this little adventure of mine showed me the importance of establishing positive habits. When your daily life changes dramatically it's easier to rely on strong habits than on willpower. So I was able to keep logging my meals even when I was stuck on my hospital bed and to resume walking (well, limping is a more accurate description) a few hours after the surgery.

TL;DR: Resistance Training (RT) has many potential benefits even for people with CVD (cardiovascular disease). Excessive BP (blood pressure) elevations have been documented with high-intensity RT (80% to 100% of 1-RM) but such elevations are generally not a concern with low- to moderate-intensity RT performed with correct breathing technique and avoidance of the Valsalva manuever (holding your breath while lifting).

Resistance Exercise in Individuals With and Without Cardiovascular Disease: 2007 Update. A Scientific Statement From the American Heart Association Council on Clinical Cardiology and Council on Nutrition, Physical Activity, and Metabolism
http://circ.ahajournals.org/content/early/2007/07/16/CIRCULATIONAHA.107.185214.citation

From the abstract: "Prescribed and supervised resistance training (RT) enhances muscular strength and endurance, functional
capacity and independence, and quality of life while reducing disability in persons with and without cardiovascular
disease."

So far so good. Then as far as RT is concerned a distinction is made between static (isometric) exercise (no movement of the limb) and Dynamic (isotonic) exercise, which causes movement of the limb.

"During isometric exercise, increases in HR (heart rate) and both SBP (systolic blood pressure) and DBP (diastolic blood pressure) are nearly proportional to the force exerted relative to the greatest possible force that an individual can evoke (percent maximum voluntary contraction [MVC]) rather than the absolute tension developed."

"The combination of vasoconstriction and increased cardiac output results in a disproportionate rise in SBP, DBP, mean BP, and peripheral vascular resistance. These pressures continue to rise throughout the duration of the exercise. Thus, a significant pressure load is imposed on the cardiovascular system, presumably to increase perfusion to the contracting skeletal muscle."

"The impact of the Valsalva maneuver (a forced expiration is invoked against a closed glottis, holding your breath while lifting) and high levels of muscle tension to lift or otherwise move a heavy weight can result in somewhat dramatic changes to the physiological responses to RT. Depending on the duration and intensity of the maneuver and the resistance, an increase in intrathoracic pressure leading to decreased venous return and potentially reduced cardiac output may occur. The physiological responses are an increase in HR to maintain cardiac output and vasoconstriction to maintain BP, which otherwise may decrease with decreasing cardiac output. At the release of the “strain,” venous return is dramatically increased, increasing cardiac output, which is now circulating through a somewhat constricted arterial vascular system. The result is a rise in BP, potentially quite dramatic, that may require minutes to return to baseline."

Now for dynamic (isotonic) exercise there is a: "[...] combined volume and pressure load. The level of the developed pressure load depends on the magnitude of the resistance (percent MVC) required and the duration of the muscle contraction in relation to the intervening rest period. Thus, a smaller pressure load on the cardiovascular system will occur during this type of exercise if the relative resistance is not too great, the contraction period is relatively short (1 to 3 seconds), and there is at least a 1- to 2-second rest period between contractions. The magnitude of the volume load on the cardiovascular system during a dynamic-resistance exercise will be greater when the magnitude of the resistance is relatively low (able to complete 20 to 30 repetitions) and the contractions are performed every few seconds. Specifically, and again depending on the duration and intensity of the resistance exercise, HR can substantially increase and may approach age-predicted maximum, that is, HR achieved with treadmill exercise testing. Blood pressure responses, both systolic and diastolic, may potentially surpass values achieved during standard exercise testing."

"The effects of RT on the cardiovascular system have been studied in individuals with and without CVD and have been summarized in several reviews. The results represent a consensus of findings in which the lack of unanimity is attributable to multiple factors, including specific type, intensity, and duration of RT."

"Studies of cardiac morphology and function have consistently shown that the alterations associated with RT are physiological, although certain cardiac effects exist on a continuum between normal and pathological. Intensive RT characteristically increases left ventricular (LV) wall thickness and mass, with little or no change in LV diameter. Although statistically significant, the increase in wall thickness is modest, and values are generally in the upper range of untrained, normal subjects."

Safety of RT

"Both research findings and clinical experience indicate that resistance exercise is relatively safe. [...] Although excessive BP elevations have been documented with high-intensity RT, for example, 80% to 100% of 1-RM performed to exhaustion, such elevations are generally not a concern with low- to moderate-intensity RT performed with correct breathing technique and avoidance of the Valsalva manuever."

"The use of resistance testing and training in moderate- to high-risk cardiac patients requires good clinical judgment and close monitoring. Studies in healthy adults and low-risk cardiac patients, that is, persons without resting or exercise-induced evidence of myocardial ischemia, severe LV dysfunction, or complex ventricular dysrhythmias, have reported no major adverse cardiovascular events. RT also appears to be safe among patients with controlled hypertension, and intra-arterial BPs during weight lifting in cardiac patients are reported to be within a clinically acceptable range at 40% and 60% of 1-RM."

"The application of RT in the rehabilitation of patients with CHD has been reviewed. [...] The absence of anginal symptoms, ischemic ST-segment depression, abnormal hemodynamics, complex ventricular dysrhythmias, and cardiovascular complications suggests that strength testing and training are safe for clinically stable men with CHD who are actively participating in a supervised rehabilitation program."

"Vigorous or high-intensity RT should not be initiated for persons without prior exposure to more moderate resistance exercise independently of age, health status, or fitness level. "

Absolute and Relative Contraindications to Resistance Training

Absolute:

Unstable CHD
Decompensated HF
Uncontrolled arrhythmias
Severe pulmonary hypertension (mean pulmonary arterial pressure >55 mm Hg)
Severe and symptomatic aortic stenosis
Acute myocarditis, endocarditis, or pericarditis
Uncontrolled hypertension (>180/110 mm Hg)
Aortic dissection
Marfan syndrome
High-intensity RT (80% to 100% of 1-RM) in patients with active proliferative retinopathy or moderate or worse nonproliferative diabetic retinopathy

Relative (should consult a physician before participation):

Major risk factors for CHD
Diabetes at any age
Uncontrolled hypertension (>160/>100 mm Hg)
Low functional capacity (<4 METs)
Musculoskeletal limitations
Individuals who have implanted pacemakers or defibrillators