The Importance of Dosage in Manual Therapy
Originally published in Massage Today.
Research is slowly beginning to reveal the importance of optimal dosage in manual and movement therapies and it may surprise you (as it did me) to learn that very small variations in applied load (compression, stretch, etc.) can make the difference between a positive and a negative therapeutic outcome.
Recent studies have shown that variations in the:
- Degree (how much force?)
- Duration (for how long?)
- Velocity (at what speed?)
- Amplitude (over what distance?)
- Frequency (how often?)
- And even the direction – of therapeutic force being used – can significantly influence whether clinical outcomes are positive, negative or neutral.
This list should include other variables, such as whether a particular method is used alone, or in combination with others (say, stretching as well as effleurage) – and when employed with other methods – and in what sequence. In other words – how much is too much, and how much is too little?
Evidence is also emerging that the unique characteristics of the client/patient who is receiving treatment – the gender, age, past and present medical conditions, degree of physical fitness etc – are all factors capable of modifying the responses to manual treatment. (Dennenmoser, et al, 2016)
The following examples, taken from recent research studies by hand surgeons, offers us glimpses of the emerging evidence. Wang & Guo (2012) showed that quite different effects emerge when damaged tendons are mechanically loaded, for example, involving stretching. When 4% of tendon stretch was used, there was a reduction of collagen production and tensile strength of the tendon but an increase in catabolic (break-down) of tissues, slowing healing after trauma or surgery. However, 8% of tendon stretch increased collagen production (essential in the repair process) and the tendon’s tensile strength, plus differentiation into tenocytes (needed for creation of new tendon tissue), while reducing formation of adhesions and inflammation. This encouraged more rapid healing after trauma or surgery. In contrast, a 12% stretch reduced collagen production and organization, while increasing inflammation, edema and tenocyte differentiation, slowing down healing after trauma or surgery.
That’s the basic science, but it leaves a major (as yet unanswered) question: How are you to know the difference between loading tendons to match the ideal (8%), while avoiding the less effective degrees of load (4%, 12%) in practice, in a clinical setting?
Other examples of the clinical challenge of achieving an ideal degree of load during treatment emerge from another basic science study by Zein-Hamoud & Standley(2015). They report that, “The key components of the response to mechanical forces are fibroblasts, which [tend to] respond to different types of strain by secreting anti-inflammatory chemicals and growth factors, thus improving wound healing and muscle repair processes.” They also note that, “Heterobiaxial, but not equibiaxial, strain affects fibroblast morphology – [likely due to]- actin, which mediates strain-induced cellular Ca++ release.”
In their study involving fibroblast behavior during the repair of a damaged bioengineered tendon, these innovative scientists identified that:
- Approximately 6% of load (stretch), as well as the direction (heterobiaxial involving different degrees/directions of strain), for 4 to 5 minutes had beneficial effects.
- “Too much’ or ‘too little’ load, for too long, or not long enough, retarded healing, particularly if the load was equibiaxial (equal strain across both axes).
The question arises again: How is a practitioner/therapist to know the difference between loading soft-tissues with the beneficial degree of force, approximately 6% compared with the less helpful 3% or 12% , in order to match these findings? Clearly many therapists get this right, and my personal experience and opinion is that methods that meet tissue resistance and engage restriction barriers heterobiaxially and non-forcefully (as for example in Myofascial Release, or gentle Muscle Energy Technique application), are closer to achieving the ideal, than those that employ more aggressive forms of load.
Of course, the examples described above only highlight the treatment part of the equation. There is of course another element; the nature of who and what is being treated. Dennenmoser et al, (2016), explain the results of research involving applied mechanical friction: “Electrical impedance…can be used to determine the amount of water within human tissue and to differentiate between intracellular and extracellular water. Ultrasound elasticity imaging directly reveals the physical property of fascial tissues and makes it possible to quantify changes in tissue thickness as well as stiffness before and after [treatment].” Their results revealed that the tissue (muscle and fascia) responses will be quite different depending on numerous features that are only partially related to the way treatment is applied. “Besides the expected softening-effects on the lumbar region, both kinds of tissue, musculature and fascia, react differently depending on the sex, age, pain-history and activity-level of the person”
Dosage in manual therapy is an area that is both under-researched and “under-translated” into practice, and all manual professions need to focus on ways of teaching and training that encourage optimal delivery of therapeutic load. Additionally, attention the nature of the individual and the tissues being treated presents a further educational challenge that requires our attention.
- Chaitow L 2015 Manual therapies and hypoalgesia: What are the mechanisms? Journal of Bodywork and Movement Therapies, Volume 19(3):389-390.
- Dennenmoser S et al 2015 Clinical mechanistic research: Manual and movement therapy directed at fascia electrical impedance and Sonoelastography as a tool for the examination of changes in lumbar fascia after tissue manipulation Journal of Bodywork and Movement Therapies, 20(1):145.
- Voogt L et al. 2015 Analgesic effects of manual therapy in patients with musculoskeletal pain: a systematic review. Man. Ther. 20(2):250-256.
- Wang & Guo 2012 Tendon biomechanic & Mechanobiology Jnl. Hand Therapy 25:133-140.
- Zein-Hamoud M Standley P 2015 Modeled Osteopathic Manipulative Treatments. Jnl. American Osteopathic Association 115(8):490-502.
Article by Leon Chaitow, ND, DO. Originally published here.