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About Dynamics

Dynamics is a physical therapist owned and operated out-patient physical therapy clinic devoted to providing excellent rehabilitative services. 

 Three convenient locations in Northern Virginia; 

Herndon, Gainesville, and Haymarket.


No Prescription Required

Most Insurances Accepted

  Early and Late Evening Appointments Available.  


 Our Philosophy

Individualized, progressive physical therapy is Dynamics’ approach to successful rehabilitation.  Our therapists realize that every person and every injury is unique.  We use state-of-the-art equipment, manual therapy techniques and personal treatment plans to underscore our philosophy of individualized care.  Most importantly, as a Dynamics patient, you will work with the same provider at each therapy session.  This 1:1 treatment and particular attention to each of our patients ensures they will recover as quickly as possible. 

An individual plan of care is written by your therapist after your first visit to Dynamics.  This treatment plan includes unique goals along your path to recovery.  We share your plan with your physician and quite often, send intermittent progress notes as well.  This open communication not only enables you to discuss your rehabilitation at scheduled appointments, but ensures a continuum and coordination of your care.  It is another key to the individualized, progressive physical therapy that Dynamics offers in optimizing your recovery. 

Located in Herndon, Gainesville and Haymarket we have formed close working relationships with many of the medical establishments in the surrounding area.

By maintaining open lines of communication between the referring physician and our therapists, we are confident we can achieve or exceed our patient's goals.


Voted 'Best Physical Therapy' in Haymarket for 2016 and 2017!

Honorable Mention for 2013-2015


"The staff was great! They really helped alleviate some of my hesitation regarding therapy. Everything was very positive and I met my goals. I could not ask for more. "

Doctors and Staff


Select your therapist below to view their individual page information 


David Sahley, DPT, OCS, COMT   


Karen Jensen-Vick, DPT, COMT


Joanne Balint, DPT  


Jennifer Dyson,  DPT  

Karen MacLean, PT

Brenda Sale, LPTA

Our Staff

Together, our team possesses decades of experience and extensive training in the clinical setting. Dr. David M. SahleyDr. Karen Jensen-VickDr. Joanne Balint, and Dr. Jennifer Dyson – have a Clinical Doctorate (DPT) in Physical Therapy. Dynamics also has a licensed physical therapist Karen MacLean and a licensed physical therapy assistant (LPTA), Brenda Sale

Our providers have extensive specializations.  With manual therapy certifications (COMT), a vestibular certification, and orthopaedic specializations (OCS) held by the staff at Dynamics, you can be sure that the latest techniques and methods will be used during your treatment. Not only do our therapists foster an environment for learning, by hosting interns and students in the practice on a regular basis, but they can also be found lecturing at local universities and colleges. Our founding therapist, David Sahley, is currently a nationally-recognized instructor in manual therapy techniques for Maitland Australian Physiotherapy Seminars.


Dr. David Sahley, DPT, OCS, COMT


Dave graduated from Physical Therapy School at Marymount University in 2000. Prior to opening Dynamics Physical Therapy in 2002, he managed an outpatient orthopedic clinic in Northern Virginia.

Dave is an Orthopedic Certified Specialist (OCS), a Certified Orthopedic Manual Therapist (COMT), a credentialed Clinical Instructor and a senior instructor for Maitland Physiotherapy Seminars.

He helps instruct continuing education courses focusing on the spine and the extremities to his peers nationally, as well as giving seminars on injury prevention and treatment for a host of diagnosis to the community locally. He is a member of the American Physical Therapy Association (APTA) and the American Academy of Orthopedic Manual Physical Therapists (AAOMPT).  

In his spare time, Dr. Sahley enjoys traveling, scuba diving, playing soccer, and spending time with his family. 

Dr. Sahley works in our Herndon location on Mondays, Wednesday and Fridays.

He works from our Gainesville location in the Heritage Village Plaza on Tuesdays and Thursdays. 




"Dr. Dave Sahley, basically saved my life. After an unusual ADR spine surgery overseas, and me being a very complicated case, Dave took the time very cautiously to assess, treat, and have a regimed 4 month protocol. He did wonders for me, and got me a functional life back (which I never though I would ever gain). I’ll be forever grateful for Dave, along with the entire staff. Other PT’s royally treated me like an assembly line, didn’t understand the anatomy, made me worse, along with not knowing how to treat ADR (which is a completely different approach than a fusion). His knowledge, skills, one on one approach, and attentiveness were bar none amazing! His name goes down in history as “ Diamond Dave!!” Thanks again dynamics PT!"- Jordan K. 

"Dr. David Sahley's assesement of my injury, and his subsequent plan of treatment, have made a world of difference. He made me feel motivated to continue his recommended exercises after the entire process ended. Very grateful." - Joanne W. Herndon Location

"Dr. Dave is THE BEST Physical Therapist I have found. He is truly a gem among.... I've learned how to care and do my excerises correctly. Dr. Dave has taught me all in less than a month, and most importantly, I AM PAIN FREE." - Herndon Patient

"I have known and utilized the services of Dr. Sahley for 10 years now. He and his staff are very professional and I highly recommend him and his team as the best in the business!"
- E.L, Gainesville Location

" I am 69 years old and had both of my knees replaced. I went to Dr. Dave Sahley for Physical therapy and liked that he takes a holistic approach to rehabilitation. He helped me get my range of motion back and I learned a variety of exercises I can do for maintenance going forwrad. He is compassionate, knowledgable, and very trustworthy professional. I highly recommend him and his team."- Gainesville Patient.


Dr. Sahley is a senior instructor for the Maitland Physiotherapy Seminars, and teaches manual therapy courses nationally. 

Dr. Karen Jensen-Vick, DPT, COMT

Dr. Karen Jensen-Vick received her Bachelor of Science degree from Arizona State University's Honors Colloquium. She graduated Magna Cum Laude after completing her original research for her Honors Thesis. She then relocated to Maryland, where she attended physical therapy school at the University of Maryland, Baltimore to complete her Master's in Physical Therapy degree. While there she published her Master's degree research regarding the orthopedic surgical intervention of the limb lengthening surgical technique and rehabilitation. While practicing as a full-time physical therapist, she completed her Doctor of Physical Therapy degree at the University of Maryland, Baltimore, School of Medicine.

Her special interests include rehabilitation after all sports injuries/surgeries, rehabilitation after joint replacement surgery and related procedures at the neck, shoulder, elbow, spine, hip, knee, and ankle, and physical therapy interventions for high school and college athletes. Her professional memberships include the American College of Sports Medicine and the American Physical Therapy Association (APTA), where she is also a member of the Sports Physical Therapy Section and Orthopedic Physical Therapy Section. She is a practicing manual therapist at the Herndon office of Dynamics Physical Therapy, and recently earned her Certification in Orthopedic Manual Therapy (COMT) in October 2014.

In her spare time, Dr. Jensen-Vick enjoys traveling, hiking, and biking. She also enjoys reading and spending time with her husband and her Norwegian Elkhounds.

Congratulations Dr. Jensen-Vick. For more information on her C.O.M.T.- Click Here!

Dr. Jensen-Vick works from our Herndon location (inside Gold's Gym Clocktower) on Tuesdays and Thursdays.


"Dr. Vick was FANTASTIC! My son is a high school footbacll player who tore his ACL- he was not the easiest person to work with. He loved Dr. Vick- She gained his respect immediately and explained everything to him. He rehabed beautifully AND very quickly. He even said he misses going to PT!! Now, THAT is a compliment." 

"The assesment before my treatments was very thorough and determinded my individual program for treatment and improvment. Dr. Karen was very encouraging, and held me responsible for doing my "homework" daily." - R. Redler. "

Great facility and good treatment received. Karen is a very nice experienced therapist and exceeded my expectations in my recovery of my knee. Jasmine and Erika at the front desk are amazing people. Overall I give 5/5 rating for my treatment. Thank you!"

"Karen is GREAT! She was a perfect fit for my rehab. I have already referred her to others." 

"I was very pleased with the treatment DR. Karen Jensen- Vick provided. She cares for her patients and enjoys what she does. I would recommend her and certainly go to her again if needed. Thanks Karen." 

Dr. Joanne Balint, DPT

Dr. Joanne Balint earned her master’s degree in physical therapy (MPT) from Marymount University in 2002 and received her physical therapy doctorate (DPT) from Shenandoah University in 2007. 

Dr. Balint specializes in post-concussion and vestibular therapy (vertigo, dizziness and balance disorders). 

Over the last three years, she has successfully treated a broad spectrum of patients, from the very young to the elderly.  Dr. Balint received her certification in vestibular therapy from the American Physical Therapy Association through Emory University in 2011. 

In addition to her physical therapy degrees, Dr. Balint holds a master’s degree in science education and has taught at both the undergraduate and graduate levels for over a decade.  She has served as a guest lecturer at Marymount University with a focus on post-concussion rehabilitation and currently teaches pathophysiology at Northern Virginia Community College. 

Joanne Balint was featured in the December 2014 edition of Your Health Magazine.

You can read Dr. Balint's article on Concussions and Vestibular rehabilitation, Here.


Dr. Balint is in our Gainesville Location in Heritage Village Plaza on Monday, Wednesday, and Thursday evenings

"Dr. Balint is very knowledgable and she related well with my daughter.She took the time to explain things on her level and I appreciated her kindness and patience." 



Dr. Jennifer Dyson, DPT

A graduate of Shenandoah University, Jennifer Dyson holds her Doctorate in Physical Therapy.  As a competitive cheerleader for many years, her passion for physical therapy began when she suffered a sport-ending shoulder injury and became a patient herself.  Dr. Dyson underwent surgery and subsequent successful rehabilitation through physical therapy.  Combining this personal experience and her professional education, Jennifer has a special interest in the rehabilitation of shoulder injuries.  She is excited to join the Dynamics Physical Therapy team and looks forward to developing individual treatment plans with her patients, to achieve successful outcomes just as she personally experienced.

In her spare time, Dr. Dyson enjoys going to country concerts, and the beach, with friends and family.

Dr. Dyson is in our Gainesville location in Heritage Village plaza Monday through Friday.


" First let me say, after 76 years of being involved in vigorous physical activities, ive had some bouts with a sore back. This past bout had me unable to walk without some major pain. I entrusted Dynamics Physical Therapy with the task of getting me back to an active lifestyle. Dr. Jennifer Dyson began my recovery program just before Christmas 2017. Two sessions a week during January at Dynamics, plus daily assigned exercise at home, had put me back in tip top shape by the first week for February. No pain walking, dancing, workouts at my local gym. In addition to my recovery, upon leaving, I was given advice on the best methods of personal back care. I would definitely recommend Dynamics Physical Therapy to anyone needing recovery therapy." - D. Fisher 

Jennifer did an excellent job- good at explaining what she was doing and why I was doing the numerous exercises. I would use her again and I would refer her to my family and friends."- Suzanne C.

"Jennifer Dyson is an excellent Physical Therapist. She helped me understand my MRI results better than my doctor. I highly recommend her."- Patient Survey

"In addition to my therapist, Dr. Jennifer Dyson, the manager, Jessica, was excellent! Jennifer provided solid professional assesment and therapy- adjusting the treatment according to progress. Jessica worked tirelessly on my insurance. I was in excellent hand."- Barbara M. 

"AFTER 30 YEARS OF CHRONIC PAIN, I AM NOW PAIN FREE! Jennifer works MIRACLES!! Thank you so much."

"I never have had the kind of attention or skill in receiving treatment as I've had at Dynamics Physical Therapy. The entire staff, but Dr. Dyson in particular, were outstanding!" 

Karen MacLean, PT


After graduating from Glasgow Caledonian University in 1995 with a BSc (honors) in Physical Therapy, Karen left her native Scotland to pursue a career in the United States.  She began practicing therapy in New Orleans, Louisiana before relocating to Virginia a decade ago. 

Now, with 20 years of clinical experience, Karen joins Dynamics with an expertise in outpatient therapy.  She specializes in manual physical therapy, orthopedics, sports physical therapy and running injuries.  As a member of the American Physical Therapy Association, Karen also has experience treating a mix of neurologically involved and generally deconditioned patients and is a certified lymphedema therapist.

Karen is happily married to Graham and is the mother of three daughters. In their spare time they enjoy traveling, sports and exploring new places together.

Karen works in our Piedmont Center Plaza location Monday through Friday.


 "Karen MacLean is awesome! I've grown to trust her in every way. She takes the time to listen to all your concerns, her 'bedside manner' is wonderful. She care not only about resolving the current issue, but improving your strength and flexibility for long term wellness!"

"From the off, my experience with Dynamics has been nothing but professional, flexible and courteous, the  team will always work with my volatile schedule to fit me in "Karen " is an amazing therapist, she is polite caring, professional and above all extremely knowledgeable in approaches to patient recovery...
I am hoping that in the future I do not need their services, but if I do I would have no hesitation in using Dynamics to aid in my recovery."- A.C. Via Yelp

"I have had several different therapies at other places and your treatment and therapists are absolutely the best! Every aspect of my treatment was wonderful! Karen has a great ability to treat and educate, and does so in a kind, caring way. Megan was a great assistant and very dedicated. Thank you Dynamics." C. Wilson.

"I actually looked forward to my therapy appointments.  The receptionists were both very friendly and helpful.  Karen, my therapist, was very knowledgeable and really cares about her patients.  I made steady progress thanks to her treatment and advice.  Very clean and modern facility."- B.Q. Via Yelp

Brenda Sale, LPTA

Brenda graduated from Longwood University in 1992 with a Bachelors degree in Sociology and Criminal Justice. She graduated from Northern Virginia Community College in 2009 with a Physical Therapist Assistant degree. She joined the Dynamics Physical Therapy team in 2009, and looks forward to working toward her Pilates certifications.

In her spare time Brenda enjoys mountain biking with her husand, playing soccer with her team and watching soccer internationally. She has traveled to Barcelona twice and is hoping to return again soon. Also, as a childhood ballerina herself, Brenda enjoys helping her daughter with her ballet training and is actively involved in her practices and recitals. 

Brenda is in our Gainesville location at 7210 Heritage Village Plaza on Tuesdays and Thursdays.


"Dave and Brenda gave me the confidence to continue progressing at home. Excellent all the way around."- Kathleen S. 

Megan Radner, LPTA

Megan graduated from University of Maryland, College Park with a Bachelor of Science in Kinesiology degree in 2014. She graduated from ECPI University in Richmond, VA with a Physical Therapist Assistant degree in 2018.

Megan played competitive soccer starting at a young age and has always had a passion for health and fitness. This sparked her interest in physical therapy and she loves working with sport-related injuries. She would also like to earn her certification as a yoga teacher in the future.

In her spare time, Megan enjoys doing yoga, cycling, wakeboarding, relaxing on the beach, trying new restaurants, and spending time with her friends and family. 

Megan works in our Piedmont Center Plaza location Monday through Friday.