Abstract
Even though the acute effects of pre-exercise static stretching and dynamic muscle activity on muscular and functional performance have been largely investigated, their effects on the corticospinal pathway are still unclear. For that reason, this study examined the acute effects of 5×20 s of static stretching, dynamic muscle activity and a control condition on spinal excitability, corticospinal excitability and plantar flexor neuromuscular properties. Fifteen volunteers were randomly tested on separate days. Transcranial magnetic stimulation was applied to investigate corticospinal excitability by recording the amplitude of the motor-evoked potential (MEP) and the duration of the cortical silent period (cSP). Peripheral nerve stimulation was applied to investigate (i) spinal excitability using the Hoffmann reflex (Hmax), and (ii) neuromuscular properties using the amplitude of the maximal M-wave (Mmax) and corresponding peak twitch torque. These measurements were performed with a background 30% of maximal voluntary isometric contraction. Finally, the maximal voluntary isometric contraction torque and the corresponding electromyography (EMG) from soleus, gastrocnemius medialis and gastrocnemius lateralis were recorded. These parameters were measured immediately before and 10 s after each conditioning activity of plantar flexors. Corticospinal excitability (MEP/Mmax) was significantly enhanced after static stretching in soleus (P = 0.001; ES = 0.54) and gastrocnemius lateralis (P<0.001; ES = 0.64), and after dynamic muscle activity in gastrocnemius lateralis (P = 0.003; ES = 0.53) only. On the other hand, spinal excitability (Hmax/Mmax), cSP duration, muscle activation (EMG/Mmax) as well as maximal voluntary and evoked torque remained unaltered after all pre-exercise interventions. These findings indicate the presence of facilitation of the corticospinal pathway without change in muscle function after both static stretching (particularly) and dynamic muscle activity.
Highlights
Static stretching (SS) is traditionally incorporated into pre-exercise routines in rehabilitation and sporting environments [1]
EMG data collected during static stretching were lower than 3% of the EMG recorded during the MVIC, which confirms that no muscle contraction occurred during stretching [27]
No significant main or interaction effects were observed for EMGMEP, EMGHmax and EMGMmax in SOL (P = 0.67, P = 0.22 and P = 0.41, respectively), gastrocnemius medialis (GM) (P = 0.13, P = 0.07 and P = 0.12, respectively) and gastrocnemius lateralis (GL) (P = 0.41, P = 0.47 and P = 0.78, respectively)
Summary
Static stretching (SS) is traditionally incorporated into pre-exercise routines in rehabilitation and sporting environments [1]. Active warm-up activities (such as dynamic stretching, consisting of agonist muscle contractions to move the joint through a full active ROM and stretching the antagonist muscle [6]) are commonly implemented in pre-exercise routines. Such activities may increase joint ROM and stretch tolerance (i.e. the maximum force tolerated during stretch) as well as reduce musculotendinous stiffness [7,8]. Dynamic stretching would appear more like a dynamic muscle activity (DMA) rather than just a muscle-tendon stretching [8] Such a warm-up may be favorable in the clinical environment compared to static stretching when a minimum of time is available to condition the neuromuscular system for exercise
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
