What are the safety considerations for exercise training for oncology patients?
Whenever we put anyone on a treadmill, on a bicycle, or have them lift weights, we're increasing the physiologic demand on that patient. In most cases, they can adjust to that increased physiologic demand and perform, but every now and then you may encounter an individual who is unable to adapt to that particular increase in physiologic stress, and it can bring about serious adverse effects.
There are several contraindications for exercise testing, including the following:
- Acute MI (within two days)
- Unstable angina
- Uncontrolled cardiac arrhythmias
- Uncompensated symptomatic CHF
- Uncontrolled metabolic disease
- Severe arterial hypertension (at rest)
- Systolic BP > 200 mmHg
- Diastolic BP> 110 mmHg
First off, any sort of questionable cardiac pathology should get your attention very quickly. Unstable angina is an absolute contraindication to aerobic conditioning. When the authors speak about uncontrolled metabolic disease, in today's world they're talking about uncontrolled diabetes. You don't want to work with a patient with diabetes when his or her serum glucose levels are below 50 or over 450. In either case, it's inappropriate, and there are other medical professionals that they need to be seeing as opposed to a physical therapist.
In addition, the ACSM has set forth some guidelines with regard to blood pressure measurements that you might want to remember. The first relates to severe arterial hypertension at rest. If a patient shows up at your clinic with a systolic blood pressure of over 200, or diastolic blood pressure of more than 110, do not treat them. In my world, I would tell them to immediately be taken to the nearest ER or to their primary care physician. If it's over 200 systolic pressure, don't exercise; if it's more than 110 diastolic pressure, don't exercise. We need to take blood pressure measurements on all of our patients, cancer survivors or not.
Cardiovascular Response to Exercise
There are well-defined, well-recognized cardiovascular responses to acute exercise. The CV responses to acute exercise include:
- Increase in heart rate
- Increase in systolic pressure, and that increase can reach 200 millimeters mercury (mm Hg).
- Increase in the volume of blood pumped by the heart (i.e., cardiac output or CO)
- Increase in the amount of blood pumped per heart beat (i.e., stroke volume or SV)
- Increase in respiration rate (RR)
- Increase in the amount of myocardial oxygen consumption (MVO2).
- O2 saturation should not change much. O2 saturations should remain nearly normal in individuals that are exercising. In patients with pulmonary disease, it's a little bit of a different story. They may be safe to exercise with reduced O2 saturation, given the fact that they live in anaerobic world.
- Diastolic pressure should remain essentially unchanged with increasing exertional demand. It might go up or down by five millimeters, but it should remain within that range.
The reason I'm bringing up these points is that you need to monitor heart rates, you can monitor O2 saturations, you can pay attention to respiration rates, even if you don't measure them. You can indirectly monitor either cardiac outputs or stroke volumes by looking for changes in skin color. If cardiac output becomes compromised, a whiteish pallor sets in, which is an indirect indication of reduced delivery of blood to the skin. I mention these because if there is any change that's adverse, you're on top of it. If the heart rate doesn't go up with increasing treadmill speed, stop the treadmill and find out why. If systolic pressure doesn't go up, there's a problem. If diastolic pressure goes up too much, there's a problem. If you know what is to be expected, but it is not achieved, then you know that there is a potential safety problem. One of the things that I strongly encourage you to do is to collect as much physiologic information as possible, including heart rate, blood pressures, O2 saturation, and the patient's self-report of their perceived exertion (RPE).
When to Stop an Exercise Session
According to the ACSM Guidelines for Exercise Testing and Prescription (10th edition, 2018), there are many reasons to stop an exercise session, including:
- A drop or rise in diastolic pressure (DP) > 10 mmHg from baseline
- An excessive rise in blood pressure:
- Systolic pressure (SP) > 250 mmHg
- Diastolic pressure (DP) > 115 mmHg
- The onset of angina or angina-like symptoms
- Increasing nervous system dysfunction (ataxia, dizziness, confusion, nausea)
- Signs of poor perfusion (cyanosis, pallor) indicating a failure to maintain appropriate cardiac output
- Inappropriate shortness of breath (SOB), excessive fatigue, wheezing, leg cramps
It is worth noting that shortness of breath is not in and of itself pathologic. If you have watched a football game recently, you saw healthy individuals experiencing shortness of breath. It's very appropriate, you expected it, you anticipated it, and you wouldn't give it another thought. However, for patients, their shortness of breath may be inappropriate. If they're walking across a level, flat surface and they're short of breath, there's something not right there. But if you've had them do a high-intensity interval workout and they're short of breath, you would expect that. Now that doesn't mean you can ignore it, but you can look at their heart rates, you can ask them how they're feeling, and make sure that all these other signals of safe physiology are also appropriate. You need to put shortness of breath in the context of where it's occurring, and then you have to ask yourself is that context safe or unsafe?
*from the course Incorporating Exercise Training into the Oncology Rehabilitation Setting