Manual Therapy and Heart Rate Variability in Long-Standing Neck Pain: An Evidence Summary for Therapists

Introduction
Neck and back pain result in the loss of more than 150 million workdays annually in the United States. This translates to approximately 16 billion dollars in lost productivity, with adults aged 40 to 65 accounting for nearly half of these losses. Neck pain is one of the most prevalent musculoskeletal complaints, affecting up to 65 percent of individuals over their lifetime. Around one in five people will continue to experience symptoms each year, making neck pain the fourth leading cause of disability worldwide. Chronic or long-standing neck pain, which lasts longer than three months, is also frequently associated with dysfunction in the autonomic nervous system, the part of the nervous system responsible for involuntary bodily functions.

Heart Rate Variability
Heart rate variability is a non-invasive, objective measure of the balance between the sympathetic nervous system (which activates the body’s stress response) and the parasympathetic nervous system (which promotes rest and recovery). Low heart rate variability reflects increased stress or decreased adaptability and has been linked to persistent pain conditions, cardiovascular risk, and diminished ability to recover from physical or psychological stress. Higher heart rate variability is associated with improved autonomic regulation, greater resilience, and better overall health.

The Role of Manual Therapy
Manual therapy is a hands-on clinical technique used by various health professionals including physical therapists, osteopaths, chiropractors, massage therapists, and practitioners of traditional manual techniques such as acupressure and shiatsu. It involves passive movements of joints and soft tissues, including joint mobilization, manipulation, massage, and myofascial release. These techniques have long been thought to influence the autonomic nervous system and are commonly used to alleviate pain and improve physical function.

Objective of the Review
A review published in 2023 Scandinavian Journal of Pain aimed to determine whether manual therapy can positively influence autonomic nervous system function—as measured by heart rate variability—in adults with long-standing neck pain. Additional outcomes included changes in self-reported pain, disability levels, and overall quality of life.

Study Selection and Analysis
Following a comprehensive search, only three studies met the criteria for inclusion. These studies involved 110 participants and employed standardized measures of heart rate variability. They examined the effects of interventions such as spinal manipulation, trigger point release, acupressure, and myofascial release.

Key Findings

1. Increased Heart Rate Variability: All studies reported increases in high-frequency components of heart rate variability, suggesting enhanced parasympathetic nervous system activity. There were also reductions in low-frequency components and in the ratio between low and high frequencies, indicating a decrease in stress-related sympathetic activity.
2. Reduced Pain and Disability: Participants experienced statistically significant reductions in pain levels and disability following manual therapy interventions.
3. Modality-Specific Effects: Spinal manipulation and trigger point release appeared to have greater influence on heart rate variability and pain relief compared to acupressure or myofascial release.

Clinical Relevance
These results support the use of manual therapy for individuals with long-standing neck pain. The consistent changes in heart rate variability suggest that these treatments may not only reduce symptoms but also improve regulation of the autonomic nervous system. For therapists, measuring heart rate variability may offer an objective complement to traditional pain and function assessments.

Strengths and Limitations
This is the first systematic review to focus on manual therapy and heart rate variability in individuals with chronic neck pain. All included studies used validated equipment and standard heart rate variability parameters. However, several limitations exist: small sample sizes, lack of participant blinding, short-term outcome measurements, and gender imbalance, as most participants were female. These factors may limit the generalizability of the findings.