Gathering Hints for Myofascial Force Transmission Under In Vivo Conditions: Are Remote Exercise Effects Age-Dependent?

CONTEXT: Recent research has underpinned the occurrence of non-local exercise effects. For instance, self-myofascial release (SMR) of the plantar fascia increases hamstring extensibility. A possible mechanism consists in a mechanical force transmission across myofascial chains. However, as the degree of structural continuity in these chains decreases with age, the magni-tude of the above described remote effects might also be reduced throughout lifespan.

OBJECTIVE: To examine the age-dependency of non-local exercise effects following plantar fascia SMR.

DESIGN: Regression experimental study.

SETTING: General population.

PARTICIPANTS: 168 healthy participants (45±21 years, 85 males).

INTERVENTION: One 120 s bout of plantar foot SMR, performed in standing position.

MAIN OUTCOMES MEASURE: Hamstring extensibility was assessed using sit and reach testing. Relative pre-post differences were classified as no im-provement, clinically non-relevant improvement, or clinically relevant improvement according to previously published data. The age-dependency of the effects was calculated by means of multinomial stepwise logistic regression. If the latter revealed other factors than age to affect treatment effectivity, their effect was eliminated using partial correlation.

RESULTS: SMR in-creased hamstring extensibility by 10.1% (pre: 24.9±9.7 cm, post: 27.4±9.3 cm, p<.0001). 99 participants (58.9 %) attained a clinically relevant change. Multinomial logistic regression demonstrated no influence of sex, amount of physical activity, height, BMI, and daytime, but a significant impact of baseline flexibility and age (Nagelkerke's r2 =.32, p<.001). Post hoc partial correlation analysis demonstrated that age, corrected for baseline flexibility, had a small to moderate association with treatment effectivity (r=.29, p<.0001).

CONCLUSIONS: Plantar foot SMR increases hamstring extensibility, which is explained by age to a small degree. Additional research is warranted in order to delineate the substrate of remote exercise effects. Besides mechanical force transmission, also cortical adaptations might represent the driving factor.