Editor’s note: Eight young pain researchers were recently selected to provide interviews, news articles, and other content as part of PRF’s Virtual Correspondents Program, which provides a science communications training experience for program participants. The following interview comes courtesy of PRF Correspondent Andrew Post. (Also see the Correspondents’ blog posts here.)
Marie Hoeger Bement, PhD, is a professor in the Department of Physical Therapy at Marquette University in Milwaukee, Wisconsin, US. A pain researcher, and also trained as a physical therapist, she is examining the effects of exercise on pain, psychological factors that contribute to pain, and also has a strong interest in pain education. Recently, she spoke with Andrew Post, a PRF Virtual Correspondent and PhD student at the University of Iowa, Iowa City, US, to discuss her journey from physical therapy to pain research, her current work, and future directions of her lab, among other topics. Below is an edited transcript of their conversation.
You started at the University of Iowa, with Dr. Kathleen Sluka serving as your PhD advisor, and did basic science research there. Now you do clinical research. Could you talk me through your career path and how you got into pain research?
I started out as a physical therapist, having graduated in 1997 with a master’s degree in that field. As a new physical therapist, I was on the chronic pain team and quickly realized that we needed to do a better job, as physical therapists and in healthcare overall, in how we help people who are in pain. This lack of knowledge was the main factor for my returning to graduate school, getting my PhD, and working with Kathleen Sluka at the University of Iowa.
While I was at the University of Iowa, I was fortunate to look at the mechanisms of chronic pain and, in particular, the role of the cAMP pathway in an animal model of chronic muscle pain. As a side project, I was also able to study the influence of low-intensity exercise with the same animal model.
After I graduated, I accepted a tenure-track faculty position at Marquette University in 2004. I am fortunate to be in a premier physical therapy program that also supports my pain teaching and research. While at Marquette, I transitioned from working with animals to working with human participants; one of the main reasons why I chose Marquette was because of the very strong exercise science program there, and I wanted to pursue my research investigating nonpharmacological treatments while continuing with an exercise focus.
What research activities are going on now in your lab?
Since starting at Marquette University, I have expanded upon how I view and assess pain. Clearly, the emphasis on the biopsychosocial model, as well as incorporation of quantitative sensory testing [QST], has shaped my research.
For example, when I first started in exercise research, I mainly used pressure pain thresholds, which is a static measurement, but now we’ve progressed to more dynamic measures such as conditioned pain modulation [CPM] and temporal summation of pain to assess central pain inhibition and facilitation, respectively. This progression has impacted my research in that we can look at how exercise impacts the local exercising muscle and central pain modulation using all of these approaches. Also, considering other biopsychosocial factors, our work has expanded to look at the impact of pain catastrophizing, stress, body composition, age, fatigue, and physical activity levels on pain sensitivity at rest and following exercise.
Conditioned pain modulation and pain pressure thresholds are often viewed as laboratory assessments. What utility do those measurements have in clinical practice? And what are some of the barriers to their use?
From a QST standpoint, there is a lot that we can learn and apply to the clinical setting. We and others have shown that QST can characterize pain conditions to get a better idea, for example, of the involvement of central sensitization. QST can also be used to assess how treatment interventions impact endogenous pain modulation. For example, we can identify how exercise impacts central pain facilitation and inhibition. We have also shown that CPM efficiency predicts hypoalgesia following static contractions of the arm in healthy young and old adults; those with greater CPM reported greater pain relief with exercise. In chronic pain populations, QST may be used to explain why some people have pain relief while others have symptom exacerbation when initiating exercise. So there’s a lot of potential with how we can incorporate QST, both from a clinical and a research perspective.
There are also some limitations with using QST in that we do not have standard protocols with a lot of our techniques. For example, with CPM, how do different types of conditioning and/or test stimuli influence CPM efficiency? Should we look at the absolute or relative change in pain associated with the testing stimulus? How does the application site influence outcomes? For example, we and others have shown that CPM and pressure pain thresholds differ by body region. These are important issues as we translate our findings and techniques to the clinical setting and for establishing minimal clinically important differences with the various QST protocols.
Your work has focused on the impact of exercise on chronic pain and also on how it affects healthy populations. What are some of the most notable findings you’ve had, especially with regard to the effects of age and sex on exercise-induced hypoalgesia?
A lot of the early exercise research incorporated young and healthy participants, who are also typically pretty active. When we first started studying exercise, we followed a similar population in that we studied college students. With exercise prescription, we found that isometric contractions of higher intensity and longer durations produced the greatest hypoalgesia in young healthy adults. In older adults we also looked at the role of the intensity and duration of isometric contractions; when we first started looking at this, I was really struck by the lack of literature on how the effects of exercise prescription on pain may change with age. What we found was similar hypoalgesia in our older adults whether the exercise was high intensity, low intensity, or for a shorter or longer duration. These findings suggest that the optimal exercise prescription for pain relief likely differs as we age. It’s also important to realize that with exercise, not only are we interested in pain relief, but also in improving function.
One issue with aging is sarcopenia, which is an age-related loss of muscle mass. Therefore, strength training should be a priority with older adults to help combat the subsequent strength and functional deficits.
We also looked at sex differences, though it was not our primary aim. But since we were looking at both men and women and how they respond to exercise, we did see some trends in that women tended to experience greater hypoalgesia following isometric contractions than men did. However, when we matched them for baseline pain, we were surprised that men experienced greater hypoalgesia. Therefore, from a sex difference perspective, there are a lot of unknowns with how men and women respond to exercise and the potential pain response. Interestingly, we have shown that lean mass mediates the relation between thermal temporal summation and sex in young healthy adults. This finding provides insight into potential benefits of exercise and how activities that increase lean mass, such as strength training, may improve central pain facilitation.
How should clinicians take such findings into account when considering exercise dosage and the interventions they should really be focusing on with their patients?
How someone responds to exercise likely depends on the person’s pain status. For example, as you mentioned earlier, in addition to studying the benefits of exercise in healthy participants across the lifespan, we are investigating how exercise impacts pain for people with chronic pain. We and others have found that there is a considerable amount of variability in the pain response following exercise for people with chronic pain; some people report an increase in pain, some have a decrease in pain, and some have no changes in pain following a single exercise session.
Our current research aims to study that variability using QST. In particular, similar to the variability in the pain response following exercise, there is variability in the degree of central sensitization in people with chronic pain. So do people with chronic pain who have less efficient CPM also report less pain relief with exercise? Can exercise restore CPM in these individuals?
Another focus of the lab is to optimize exercise prescription by studying whether the type of exercise matters. We have an NIH-funded project to look at the pain response in people with fibromyalgia immediately following different types of muscle contractions – isometric, concentric, and eccentric – and during recovery. Our preliminary data show that people with fibromyalgia report more pain during all types of muscle contractions than people without fibromyalgia. However, whether pain exacerbation occurs during the recovery period may be dependent on the type of muscle contraction.
An important caveat with our research is that we are looking at the pain response following a single exercise session, and the majority of exercise training research has shown benefits from a pain management perspective. Therefore, perhaps the type of exercise is not as important as promoting general physical activity, which should also help with some of the issues with exercise compliance. I also want to emphasize that there are hundreds of factors that may interact with how people respond to exercise including age, sex, health status, physical activity, and body composition, to name a few. I don’t think there’s one factor in particular, but rather a combination of factors that will influence how people respond to exercise, and the most important factor is the patient sitting in front of you.
What informs your research questions? Is it the scientific literature, your past work, your clinical work, or a combination of all of those things?
It’s a combination of talking with other researchers – both pain researchers and non-pain researchers such as exercise physiologists because I do exercise research. It’s also important to talk with clinicians for translation of our research to the clinic. Also crucial is talking with people who have pain. We have these great ideas about how to incorporate exercise or other approaches, but what has been most eye opening for me is talking with patients and getting their perspective regarding these approaches. I think that is huge. The most impactful conferences for me have been the ones that incorporate patient advocates, and it’s really impacted how I think about my research and what I want to accomplish.
The number one thing I’ve heard over and over from patients that really struck me is when they were asked what they want from their medical provider. They said that they want people to believe that they are in pain and not to give up on them. It’s upsetting that this is where we are at as a medical community – that people just want to be believed.
From an exercise standpoint, patient and clinician education are important to understand the variability in the pain response with exercise and to keep trying new approaches for the benefits that occur with exercise training.
Let’s change gears to discuss some of your research on incorporating pain education into the physical therapy curriculum. How are we doing in this regard? And what aspects of pain education do you emphasize at Marquette?
I was excited and grateful to be part of the 2018 Global Year for Excellence in Pain Education from the IASP. The resources available through this initiative are instrumental in training the next generation of pain scientists and clinicians.
I emphasize the pain competencies as well as the IASP guidelines for entry-level physical therapy education. It’s also important that not only do we have a pain course at Marquette University, but the pain content is integrated throughout the physical therapy curriculum, including orthopedics, neuro, pediatrics, and aging, because all physical therapists treat pain, in that the majority of our patients report some type of pain that should be part of the treatment plan.
It’s a great point that pain spans all specialty areas in physical therapy practice. Given that pain is so prevalent in any diagnosis, how do you approach collaboration with other healthcare professionals for pain management?
Every discipline brings something to the pain team. Listening is key to understanding the various ways that pain is integrated into the curriculum as well as clinical practice. Pain management is a real team effort.
With the recent emphasis away from opioids and a push for more nonpharmacological treatments, what are some of the greatest opportunities and challenges for physical activity-based treatments for chronic pain?
It’s great that there’s a renewed interest in nonpharmacological pain management. Unfortunately, due to some of the issues with opioid misuse, I also want to emphasize that the approach, whether it's pharmacological or nonpharmacological, depends on the patient; there’s a place for both approaches.
What is missing in the literature is how these approaches interact with each other. So it’s not that we emphasize one type of approach over another, but see what happens when we integrate and match the potential of both approaches to best meet the needs of the patient.
In the chronic pain population for whom physical activity may be difficult because of the pain, what can we do to further promote the benefits of exercise?
Physical therapists have an excellent foundation to help people increase their physical activity. First, we must listen to our patients to get their perspective on physical activity. Second, patient education is important to address the role of exercise as a pain management tool, in that exercise can impact most aspects of the biopsychosocial model of pain. We also must acknowledge that people may experience pain exacerbation with some types of exercise, although the type of exercise may be less important than just getting people to move; several studies have shown the benefits of walking for chronic pain, for example.
Other approaches include exercising nonpainful body parts due to the systemic effects of exercise, or to alternate between upper and lower extremities if recovery is problematic. Finally, there are modalities available that can help people with physical activity-induced pain, such as transcutaneous electrical nerve stimulation [TENS]. Kathleen Sluka and her team have shown that TENS can help decrease the pain and improve the fatigue that occur with physical activity [see PRF related news].
What advice would you give to an early-career researcher who’s interested in getting into pain research?
Read everything and talk to as many people as you can. My career has really benefited from collaborating with people both inside and outside of my pain expertise.
Along these lines, what else helped you to advance in your career?
I have been extremely fortunate to work with outstanding people, including Kathleen Sluka, Sandra Hunter, Laura Frey Law, Henrik Vaegter, and Thomas Graven-Nielsen. These individuals have helped me toward my career goal of improving pain management while training the next generation of researchers and clinicians.
Andrew Post is a PhD student at the University of Iowa, US.
Additional reading
Fatiguing exercise attenuates pain-induced corticomotor excitability.
Hoeger Bement MK, Weyer A, Hartley S, Yoon T, Hunter SK
Neurosci Lett. 2009 Mar 13; 452(2):209-13.
Pain perception after isometric exercise in women with fibromyalgia.
Hoeger Bement MK, Weyer A, Hartley S, Drewek B, Harkins AL, Hunter SK
Arch Phys Med Rehabil. 2011 Jan; 92(1):89-95.
Hoeger Bement MK, St Marie BJ, Nordstrom TM, Christensen N, Mongoven JM, Koebner IJ, Fishman SM, Sluka KA
Phys Ther. 2014 Apr; 94(4):451-65.
Hoeger Bement MK, Weyer AD, Yoon T, Hunter SK
J Clin Neurophysiol. 2014 Feb; 31(1):94-8.
Hoeger Bement M, Drewek B, Hunter SK
J Mot Behav. 2014; 46(2):107-13.
The current state of physical therapy pain curriculum in the USA: A faculty survey.
Hoeger Bement MK, Sluka KA
J Pain. 2015 Feb; 16(2):144-52.
Exercise-induced pain and analgesia? Underlying mechanisms and clinical translation.
Sluka KA, Frey-Law L, Hoeger Bement M
Pain. 2018 Sep; 159 Suppl 1:S91-S97.
Lean mass mediates the relation between temporal summation of pain and sex in young healthy adults.
Awali A, Alsouhibani AM, Hoeger Bement M
Biol Sex Differ. 2018 09 15; 9(1):42.
Does Weight Status Impact Metabolic Health in Adolescents When Controlling for Physical Fitness?
Stolzman SC, Skelton J, Harkins A, Hoeger Bement M
Pediatr Phys Ther. 2019 04; 31(2):134-140.
Alsouhibani A, Vaegter HB, Hoeger Bement M
Pain Med. 2019 Jan 01; 20(1):180-190.
A New Clinical Trial Shows Clear Benefits of TENS for Fibromyalgia ─ Finally!