Combining Passive Heating And Stretching Alter ROM, Muscle-Tendon Unit Architecture And Jump Performance

Passive heating and/or stretching used as warm up are known to improve flexibility and performance. However, the combined effects of passive heating and static stretch (SS) or dynamic stretch (DS) and these underlying mechanisms are unclear. PURPOSE: To examine the effect of combining passive heating and static or dynamic stretching on ROM, MTU architecture and jump performance. METHODS: 9 university male students completed 6 trials included SS, DS, hot water immersion (H), H followed by SS (HSS) and DS (HDS), and control as neither stretch nor H (CON) in a randomized order. SS performed 3 sets of 30 seconds for each calf. DS performed alternate dynamic calf stretch for 3 sets of 60 seconds. H consisted of immersed lower leg into 42-degree Celsius hot water for 10 minutes. At the pre- and post-each protocol, we measured maximal dorsiflexed ankle ROM and MTU architecture (muscle thickness, pennation angle and fascicle length (FL) of gastrocnemius medialis at 0°and maximum dorsiflexed ankle position (maxDF), and myotendinous junction (MTJ) displacement) using the B-mode ultrasound images. Also, drop jump reactive strength index (RSI) were measured. Significant differences between pre and post variables were determined in each protocol using a paired t-test. Also, within-group change calculated as post minus pre and one-way ANOVA with Tukey’s post hoc test was completed to identify any significant differences between groups. RESULTS: ROM significantly improved in SS (+1.7 ± 1.56°, p < 0.05), H (+2.7 ± 2.00°, p < 0.01) and HSS (+3.9 ± 2.18°, p < 0.01) but not in HDS (0.0 ± 3.46°) and DS (-0.8 ± 2.70°). HSS significantly elongated in FL at 0°(+0.3 ± 0.23 cm, p < 0.01) and maxDF (+0.2 ± 0.17 cm, p < 0.01). MTJ displacement significantly improved only in H (+0.3 ± 0.31 cm, p < 0.05) and tended to improve in HSS (+0.1 ± 0.42). Drop jump RSI in each protocol were as follows: HSS;1.65 ± 0.24 m/s, DS;1.65 ± 0.40 m/s, HDS;1.59 ± 0.23 m/s, H;1.53 ± 0.35 m/s, CON;1.49 ± 0.38 m/s, and SS;1.44 ± 0.28 m/s. CONCLUSIONS: It is suggested passive heating combined with SS may improve ROM and MTJ displacement as musculoskeletal joint. Also, both passive heating combined with SS and DS enhance acute jump performance. These results may be mainly due to passive heating reduce muscle viscosity and increase nerve conduction velocity. Supported by Grant from Sendai University.