Acute muscle and joint mechanical responses following a high-intensity stretching protocol.
OBJECTIVE
A previous study observed a joint passive torque increase above baseline ~30 min after a high-intensity stretching. This study examined the effect of a high-intensity stretching on ankle dorsiflexion passive torque, medial gastrocnemius (MG) shear modulus, and plantar flexors maximal voluntary isometric force (MVIC).


METHODS
Participants (n = 11, age 27.2 ± 6.5 years, height 172.0 ± 10.0 cm, weight 69.5 ± 10.4 kg) underwent two stretching sessions with plantar flexors isometric contractions performed: (1) 5 min before, 1 min after, and every 10 min after stretching (MVC session); (2) 5 min before, and 60 min after the stretching (no-MVC session).


RESULTS
In both sessions, no changes were observed for MG shear modulus (p > 0.109). In the no-MVC session, passive torque decreased 1 min after stretching (-7.5 ± 8.4 %, p = 0.015), but increased above baseline 30 min after stretching (+6.3 ± 9.3 %, p = 0.049). In the MVC session, passive torque decreased at 1 min (-10.1 ± 6.3 %, p < 0.001), 10 min (-6.3 ± 8.2 %, p = 0.03), 20 min (-8.0 ± 9.2 %, p = 0.017), and 60 min (-9.2 ± 12.4 %, p = 0.034) after the stretching, whereas the MVIC decreased at 1 min (-5.0 ± 9.3 %, p = 0.04) and 10 min (-6.7 ± 8.7 %, p = 0.02) after stretching.


CONCLUSIONS
The ankle passive torque increase 30 min following the stretch was not due to the MG shear modulus response; consequently, response may be due to changes in surrounding connective tissue mechanical properties.
Faculdade de Motricidade Humana, Universidade de Lisboa, CIPER, P-1100, Lisbon, Portugal. sfreitas@fmh.ulisboa.pt.|Benfica LAB, Sport Lisboa e Benfica, Lisbon, Portugal. sfreitas@fmh.ulisboa.pt.
Sandro R
SR
Freitas
Faculdade de Motricidade Humana, Universidade de Lisboa, CIPER, P-1100, Lisbon, Portugal.|Laboratory "Movement, Interactions, Performance" (EA 4334), University of Nantes, UFR STAPS, Nantes, France.
Ricardo J
RJ
Andrade
Laboratory "Movement, Interactions, Performance" (EA 4334), University of Nantes, UFR STAPS, Nantes, France.
Antoine
A
Nordez
Benfica LAB, Sport Lisboa e Benfica, Lisbon, Portugal.
Bruno
B
Mendes
Faculdade de Motricidade Humana, Universidade de Lisboa, CIPER, P-1100, Lisbon, Portugal.
Pedro
P
Mil-Homens
D000328:Adult; D000843:Ankle Joint / Q000502:physiology*; D005260:Female; D000072696:High-Intensity Interval Training / Q000379:methods*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology; D016896:Treatment Outcome; D063996:Warm-Up Exercise / Q000502:physiology*
Ankle; Elastography; Flexibility; Intensity; Medial gastrocnemius; Torque