Effect of High-Intensity Interval Training Versus Small-Sided Games Training on Sleep and Salivary Cortisol Level

<p>Purpose: The authors compared sleep quality and salivary cortisol concentration after high-intensity interval training (HIIT) and small-sided games (SSGs) performed at the habitual training time in nonprofessional male soccer players. Methods: A total of 32 players (age = 24 [6] y, height = 1.77 [0.06] m, and body mass = 75 [12] kg) were randomized into an HIIT group or an SSG<br> group. Actual sleep time, sleep efficiency (SE), sleep latency, immobility time (IT), moving time (MT), and fragmentation index were monitored using actigraphy before (PRE) and 2 nights after (POST 1 and POST 2) the training session. Salivary cortisol levels were measured before (PRE) and after (POST) training. Cortisol awakening response was evaluated. Results: Significant<br> intragroup differences in the HIIT group were noted for actual sleep time (P &lt; .0001), SE (P &lt; .0001), sleep latency (P = .047), IT (P &lt; .0001), MT (P &lt; .0001), and fragmentation index (P &lt; .0001) between PRE and POST 1 and for SE (P = .035), IT (P = .004), MT (P = .006), and fragmentation index (P = .048) between PRE and POST 2. Intergroup differences for actual sleep time (P = .014), SE (P = .048), IT (P &lt; .0001), and MT (P = .046) were observed between the HIIT and the SSGs group at POST 1 were detected. Significant intragroup variations were observed in PRE and POST salivary cortisol levels (P &lt; .0001 for HIIT; P = .0003 for SSGs) and cortisol awakening response (P &lt; .0001 for HIIT; P &lt; .0001 for SSGs). Significant intergroup<br> differences between the HIIT and the SSGs group were found at POST (P &lt; .0001) and in cortisol awakening response (P = .017). Conclusions: Changes in actigraphy-based sleep parameters and salivary cortisol levels were greater after an acute session of HIIT than SSGs in this sample of nonprofessional male soccer players.</p>