PT Classroom - Understanding the Resistive Properties of Thera-Band Tubing ׀ by Chai Rasavong, MPT, MBA


Thera-Band tubing is often utilized for therapeutic exercise both in the physical therapy setting and in a patient’s home for incorporation into a home exercise program. Therapists utilize Thera-Band tubing because it is low cost, portable, versatile and doesn’t rely on gravity for resistance (1). Thera-band tubing comes in seven colors and resistive properties are coded by color of tubing. Given its popularity, therapists are aware of the resistive properties of the tubing based on color but may be unaware of the exact resistance or force which is produced by utilizing the tubing.

Thera-Band’s website (2) states that “bands and tubing produce similar forces between similar colors. The force produced by bands and tubing is directly related to elongation. Each color will provide a specific amount of resistance at the same percent elongation, regardless of initial resting length. For example a 1-foot piece stretched to 2-feet (100% elongation) will have the same force as a 2-foot piece of the same color stretched to 4-feet. The force slowly increases as the band or tube is stretched.” Below is a chart from TheraBand’s website which charts the average force in ponds for Thera-Band elastic bands. Page, et al. JOSPT 30(1):A47. 2000 also provides a similar chart.


Average Force (pounds) for Thera-Band Elastic Bands

% Enlongation Yellow Red Green Blue Black Silver Gold
50% 2 2.5 3 4.5 6.5 8.5 14
100% 3 4 5 7 9.5 13 21.5
150% 4 5 6.5 9 12.5 17 27.5
200% 5 6 8 11 15 21 33.5
250% 6 7 9.5 13.5 17.5 25.5 40

In a study by Hughes et al. (1), they investigated the relationship between tubing length and tubing tension for 6 colors of Thera-Band tubing and estimated the resistive shoulder torque provided by Thera-band tubing during shoulder abduction exercise. Their study concluded that there is a strong linear relationship between tubing tension and tubing excursion during shoulder abduction but the resistive torque pattern provided by various levels of tubing appears to be similar to that provided by traditional isotonic exercise for shoulder abduction.

In another study by Patterson et al. (3), they conducted a study to quantify the material properties of six colors of Thera-Band tubing. In their study they investigated six aspects of force-generating potential of Thera-Band tubing: 1) the effect of the original length of the sample, 2) the effect of prestretching, 3) the effect of the rate of loading, 4) the repeatability, 5) the effect of cyclic loading and 6) the loading and versus unloading properties. Their study concluded the following 1) Length Effect- there were no differences in resistance attributable to the length of the tubing 2) Prestretching Effect – There were differences in the force-generating potential when the material was used new, directly out of the box. They concluded that prestretching at least 20 times appeared to stabilize the tubing so that it exhibited consistent force generating properties. 3,4) Repeatability and Cyclic Loading – The force-generating potential of the material was repeatable over at least 5,700 cycles. This information implies that a patient could use the same piece of new tubing for at least 6 weeks (10 reps of 4 different exercise, 3 x’s per day for 6 wks) before potentially needing another piece of tubing 5) Loading Rate – There was no effect attributable to the loading rate 6) Loading Versus Unloading – There were differences in the force-generating potential of the tubing when the material was being actively stretched and unstretched. From this data Patterson et al. was able to develop a cumulative resistance chart (click here to see article with chart) which will allow a therapist to determine which color of tubing to use to obtain a specific force level and percentage of strain.

By having an enhanced understanding of the resistive properties of the Thera-Band tubing, therapists will be able to better choose the appropriate color of Thera-Band tubing for their patient which will maximize rehabilitation potential while minimizing the likelihood for harm (3).

Last revised: October 6, 2009
by Chai Rasavong, MPT, MBA


1. Hughes C et al. Resistance Properties of Ther-band Tubing During Shoulder Abduction Exercise. JOSPT. 29(7):413-420, July 1999.
3. Patterson R et al. Material Properties of Thera-Band Tubing. Physical Therapy. 81(8):1437-1445, August 2001.

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