CLINICAL FORCE PRODUCTION OF THERA-BAND
ELASTIC BANDS. Page, P, Labbe, A,
Topp RV. HealthSouth, Metairie, LA. Supported by the Hygenic Corporation.
Purpose: The purposes of this study were to (1) quantify the resistance offered by 7 progressive colors of
elastic band (The Hygenic Corporation, Akron, OH); and (2) to determine the relationship
between resistance and percent elongation within the 7 intensities of Thera-Band
elastic band using 4
different starting lengths.
elastic bands (yellow, red, green, blue, black, silver, gold) were tested to determine
force production with elongation. Each of the 7 levels of Thera-Band
elastic bands was evaluated using
the same protocol. First, one random sample of each specific product color was cut and attached in lengths
of 18”, 24”, 30”, and 36”. One end of the band was attached to a Thera-Band
Exercise Handle. The other
end was attached to a plastic fastening clip. The plastic clip was then attached to a fixed ITC strain gauge
(Innovative Research and Development, Inc., Murray, UT), which measured the amount of resistance
generated by the band to the nearest 0.5 pounds. Each band was manually stretched at a rate of 1 inch per
second. Strain gauge measurements were recorded at 25% increases in elongation up to 250% of elongation
from the initial length of the sample. Each sample was tested five times in the same manner.
Data analysis: Stepwise regression equations were constructed to determine the relationship between
resistance and percent elongation.
Results: Linear regression equations were established for each color (Table 1). There was a strong linear
relationship (p<.000) between resistance and percent elongation for each of the 7 Thera-Band
across the four starting band lengths. The calculated r
ranged from .947 to .988.
Table 1: Regression Equations for Thera-Band
Band color Regression equation r
Yellow R = 0.788 + .0202(E) .973 .000
Red R = 1.367 + .0229(E) .947 .000
Green R = 1.525 + .0325(E) .981 .000
Blue R = 2.323 + .0443(E) .981 .000
Black R = 3.223 + .0587(E) .981 .000
Silver R = 4.053 + .0856(E) .987 .000
Gold R = 6.882 + .1350(E) .988 .000
R=resistance in pounds; E=percent elongation from initial length
elastic bands provide a consistent, linear, and predictable increase in force with
elongation across all colors
2. Regression equations can be used to clinically quantify Thera-Band
elastic resistance based on
elastic bands yield consistent percent elongation to resistance relationships within each
Clinical Relevance: Force production of Thera-Band
elastic bands is dependent on percent elongation
regardless of initial starting length. Clinicians can predict applied forces while using Thera-Band
bands in order to improve exercise dosing and prescription. These findings also provide a mechanism to
compare strength training using Thera-Band
resistance with more traditional modes of strength training
when prescribing home exercise programs.
Reference: Journal of Orthopedic & Sports Physical Therapy. 2000. 30(1):A-47-48.
Presented at the APTA Combined Section Meeting, February, 2000 in New Orleans, LA