Neuromuscular and autonomic function is fully recovered within 24 h following a sprint interval training session

Abstract

Background: Recovery is a key factor to promote adaptations and enhance performance. Sprint Interval Training (SIT) is known to be an effective approach to improve overall physical function and health. Although a 2-day rest period is given between SIT sessions, the time-course of recovery after SIT is unknown.

Purpose: The aim of this study was to determine whether the neuromuscular and autonomic nervous systems would be impaired 24 and 48 h after an SIT session.

Methods: Twenty-five healthy subjects performed an 8 × 15 s all-out session on a braked cycle ergometer with 2 min of rest between repetitions. Isometric maximal voluntary contraction (iMVC) and evoked forces to electrical nerve stimulation during iMVC and at rest were used to assess muscle contractile properties and voluntary activation before (Pre), 1 (Post_24h), and 2 (Post_48h) days after the session. Two maximal 7 s sprints with two different loads were performed at those same time-points to evaluate the maximal theoretical force (F₀), velocity (V₀) and maximal power (P_max) production during a dynamic exercise. Additionally, nocturnal heart rate variability (HRV) was assessed the previous and the three subsequent nights to the exercise bout.

Results: No significant impairments were observed for the iMVC or for the force evoked by electrical stimulation 1 day after the session. Similarly, F₀, V₀, and P_max were unchanged at Post_24h and Post_48h. Furthermore, HRV did not reveal any temporal or frequential significant difference the nights following SIT compared to Pre.

Conclusion: The results of this study show a full recovery of neuromuscular and autonomic functions a day after an all-out SIT session.

Keywords: All-out; Heart rate variability; Neuromuscular fatigue; SIT; Time course of recovery.