Founded by Dr. Brett Ashenfelter and Dr. Charles Weiss, Oak Physical Therapy provides a variety of services, including Injury Rehabilitation, Expecting and New Mother Care, Early Childhood Care, and Fitness Training, to the Greater Nashua, Amherst and Milford area. 

Physical Therapist Owned Practice
As a community-based, family-owned practice, Oak Physical Therapy is a comfortable and relaxing environment, with a commitment to one-on-one patient care. We are proud to be an independent practice with skilled and licensed professionals, who are fully committed to ensuring that every patient reaches their  recovery and wellness goals.  

Our physical therapists are dedicated to providing personalized care in a friendly and positive setting.  Our commitment to continuing education and sharing knowledge within our team ensures our patients reach timely and successful outcomes, every time.

Schedule your Initial consultation today!



Brett N. Ashenfelter

Doctor of Physical Therapy

Clinic Owner

After completing her Bachelor’s degree in Biology with an emphasis on Pre-Med studies, Dr. Ashenfelter obtained certification in Applied Behavioral Analysis from the Center for Autism and Related Disorders. She discovered that Physical Therapy was her true calling as it would allow her to combine her passions for physical activity and intellectual development in order to make a measurable difference in the quality of life of those she treated. 

In the graduate program at Franklin Pierce University, Dr. Ashenfelter worked in a diverse variety of patient clinical settings including home health care, outpatient rehab, outpatient sports PT, inpatient acute rehab, and even an animal rehab clinic, in order to maximize her exposure to many different disorders of the neurological and musculoskeletal systems and treatment methodologies.  She graduated with her Doctorate in Physical Therapy, and is licensed in the state of New Hampshire. Additionally, Dr. Ashenfelter is certified as a clinician for LSVT-BIG, the gold standard treatment for patients with Parkinson’s Disease. 

Recently, Dr. Ashenfelter was fortunate enough to give birth to a daughter of her own, and as a result, has opted to specialize in perinatal, neonatal, and early childhood services. 


Charles A. Weiss

Doctor of Physical Therapy

Clinic Owner

With a focus on compassionate evidence-based approaches to relieve pain and improve physical function, Dr. Weiss aims to make physical therapy visits as fun and relaxing as a trip to a spa while striving to exceed the benefits of traditional approaches in orthopedic physical therapy. Drawing from an academic background in research psychology, he emphasizes personalized, evidence-based strategies to maximize pain reduction.

Dr. Weiss received his Bachelor’s degree in Psychology from Whitman College in Washington State where he developed a passion for research while assisting in conducting multiple academic research projects. Dr. Weiss brought his enthusiasm for studying the mysteries of the mind with him to Franklin Pierce University in New Hampshire where he received his Doctor of Physical Therapy degree, and fostered an interest in the phenomenon of chronic maladaptive pain and the puzzle of treating it. Emphasizing a multifaceted approach to relieving pain and restoring physical function, Dr. Weiss strives to provide the highest quality care, backed by extensive research to maximize pain reduction for patients who have been struggling to find relief.
Certified LSVT-BIG Clinician


Trevor Putnam

ACE Certified Personal Trainer
ACE Certified Fitness Nutrition Specialist


As an ACE Certified Personal Trainer with over a decade of fitness training and instruction, Trevor Putnam is dedicated to creating more than mere workouts for his clients. His approach is to provide every client with a road map including simple and effective lifestyle changes that allows them to see their fitness and weight loss goals realized, all without spending money on supplements, expensive equipment, or gym memberships. An emphasis on smart, timed dietary choices, short-session bodyweight exercises, and building core strength and flexibility daily, allows clients the opportunity to make real and effective changes in their life, without sacrificing excess time and money chasing a fitness regimen that doesn't best assist them in meeting their goals. 

Making these changes the root of the fitness program ensures that a strong and healthy body is not temporary, but rather, health and fitness becomes the new normal. Trevor maintains an ongoing relationship as a health coach with every client, taking unique circumstances into account and working closely with the doctoral staff to help physical therapy patients create an active and healthy lifestyle after recovery.