Heat's role as a mechanism of dynamic stretching

• In Event: Poster Presentation and Judging for: Biomedical; Cell & Molecular Biology; Chemistry & Biochemistry; Marine Science; Systematics & Evolutionary Biology.
  In Poster Session: Biomedical Sciences Poster Session

Abstract

Before exercise, athletes perform different types of warm-up routines. Typically, this involves some variation of stretching. Static stretching has long been the standard pre-exercise protocol, but recent studies point to dynamic stretching as being more beneficial in measures such as force generation (Curry, et. al, 2009), agility, and reaction time (Chatzopolous, 2014). However, the reason why dynamic stretching causes these positive physiological effects has not been investigated. Previous studies have suggested that increased muscular temperature from dynamic stretching leads to increases in nerve conduction velocity, enzyme cycling, and muscle compliance (Behm et. al., 2015). With this in mind, our study hypothesized that an increase in muscular temperature after dynamic stretching would lead to more forceful and rapid muscular contractions. Nine undergraduate volunteers completed 3 treatments: no treatment, passive heating of the thigh, and dynamic stretching. After treatment, the temperature of participants’ dominant-leg vastus lateralis was taken. Participants then performed one leg extension while electrical activity (using an EMG) and angular acceleration (a proxy for force) were assayed. Our results showed a tendency for angular acceleration to increase as the muscular temperature increased. Interestingly, passive heating showed similar angular acceleration production to dynamic stretching but with a significantly lower frequency of electrical conduction across the muscle. This may indicate that passive heating, while producing similar increases in muscle force as dynamic stretching, requires fewer neurons to fire and less motor unit recruitment.

Authors

• Matthew Boineau, Concordia University Texas

• Rachel Boice, Concordia University Texas

• Cory Smith, Concordia University Texas

• Mary Kay Johnston, Concordia University Texas