The purpose of this systematic review was to aggregate and summarize the existing evidence on the effectiveness of deep thermotherapy for hamstring flexibility.
The PICO model for the research question and PRISMA guidelines for systemic review were the underlying guiding principles. We systematically reviewed potential randomized control trials (RCTs) indexed in PubMed, Embase, Pedro, MEDLINE, and Scopus. Two independent assessors conducted the risk of bias analysis according to the Cochrane guidelines. We also conducted a methodological quality assessment using the PEDro Scale.
Out of the 455 studies retrieved initially, 15 RCTs met the eligibility criteria. Overall, 470 participants were included in the 15 trials. Sample sizes ranged from 10 to 60.
Ultrasound therapy was employed in 40% of the studies, whereas 26.67% utilized shortwave diathermy. Only one study (6.67%) applied microwaves and 20% used Capacitive and resistive electric transfer (CReT). In addition, one study (6.67%) incorporated both ultrasound and CReT.
The results of four studies that used CReT showed greater improvements in hamstring flexibility, tissue temperature, and blood circulation than ultrasound, hot pack, and static stretching. Similarly, studies that used shortwave diathermy reported significant improvement in hamstring flexibility when shortwave diathermy was administered in combination with ice packs and stretching. Furthermore, seven studies that employed ultrasound as a deep-heating thermotherapy modality noted that ultrasound is effective if applied in combination with stretching. Some studies have shown that superficial and deep heat have the same effects on hamstring flexibility if they are used prior to stretching.
Ultrasound therapy was applied at a frequency of 1 MHz, with an intensity ranging from 1.5 watt/cm2 to 2 watt/cm2. The dominant frequency of shortwave diathermy has been reported as 27.12 MHz. The CReT was predominantly applied at a frequency of 448 KHz.
Overall, the application of deep heat using CReT, ultrasound, shortwave diathermy, and microwaves has proven to be effective in enhancing hamstring flexibility.
The results provide good evidence for clinicians to incorporate different deep heating modalities into hamstring tightness management plans. However, further research is required to determine the optimal frequency, intensity, and timing of deep thermotherapy. It has also been suggested that more attention is needed to improve hamstring flexibility in the elderly population.
hamstring flexibility
thermotherapy
