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

Background and Purpose. Warm-up prior to static stretching enhances muscle extensibility. The relative effectiveness of different modes of warm-up, ho wever, is unknown. The purpose of this study was to evaluate the effectiven ess of superficial heat, deep heat, and active exercise warm-up prior to st retching: compared with stretching alone on the extensibility of the planta r-flexor muscles. Subjects. Ninety-seven subjects (59 women, 38 men) with l imited 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)1 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 pe rform the stretching protocol. The 4 experimental groups (groups 2-5) perfo rmed a stretching protocol 3 days per week for 6 weeks. Group 2 performed t he static stretching protocol only; group 3 performed active heel raises be fore stretching; group 4 received 15 minutes of superficial, moist heat to the plantar-flexor muscles before stretching; and group 5 received continuo us: ultrasound for 7 minutes before stretching. Dorsiflexion ROM measuremen ts were taken initially and after 2, 4, and 6 weeks. Results. All experimen tal groups increased active and passive range of motion (AROM and PROM). Th e 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 de grees for group 4, and 6.20/7.35 degrees for group 5. The group receiving u ltrasound before performing the stretching protocol (group 5) displayed the greatest increase in both AROM (6.20 degrees) and FROM (7.35 degrees). Dis cussion 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.