Effect of superficial heat, deep heat, and active exercise warm-up on the extensibility of the plantar flexors

C. A. Knight, C. R. Rutledge, M. E. Cox, M. Acosta, S. J. Hall

Research output: Contribution to journalArticlepeer-review

103 Scopus citations


Background and Purpose. Warm-up prior to static stretching enhances muscle extensibility. The relative effectiveness of different modes of warm-up, however, is unknown. The purpose of this study was to evaluate the effectiveness of superficial heat, deep heat, and active exercise warm-up prior to stretching compared with stretching alone on the extensibility of the plantar-flexor muscles. Subjects. Ninety-seven subjects (59 women, 38 men) with limited dorsiflexion range of motion (ROM) were randomly assigned to 1 of 5 groups. Female subjects had a mean age of 27.6 years (SD=7.68, range=17-50), and male subjects had a mean age of 26.8 years (SD=6.87, range=18-48). Methods. The first group (group 1) was a control group and did not perform the stretching protocol. The 4 experimental groups (groups 2-5) performed a stretching protocol 3 days per week for 6 weeks. Group 2 performed the static stretching protocol only; group 3 performed active heel raises before stretching; group 4 received 15 minutes of superficial, moist heat to the plantar-flexor muscles before stretching; and group 5 received continuous ultrasound for 7 minutes before stretching. Dorsiflexion ROM measurements were taken initially and after 2, 4, and 6 weeks. Results. All experimental groups increased active and passive range of motion (AROM and PROM). The mean AROM/PROM differences at 6 weeks were 1.11/1.39 degrees for group 1, 4.10/6.11 degrees for group 2, 4.16/4.21 degrees for group 3, 4.38/4.90 degrees for group 4, and 6.20/7.35 degrees for group 5. The group receiving ultrasound before performing the stretching protocol (group 5) displayed the greatest increase in both AROM (6.20°) and PROM (7.35°). Discussion and Conclusion. Among the modalities tested, the use of ultrasound for 7 minutes prior to stretching may be the most effective for increasing ankle dorsiflexion ROM.

Original languageEnglish (US)
Pages (from-to)1206-1214
Number of pages9
JournalPhysical Therapy
Issue number6
StatePublished - 2001
Externally publishedYes


  • Exercise
  • Plantar flexors
  • Range of motion
  • Stretching
  • Thermal modalities

ASJC Scopus subject areas

  • Physical Therapy, Sports Therapy and Rehabilitation


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