Effects of psychophysiological stress on perceptual responses during low-volume high intensity interval exercise: Insights from ACTH and cortisol in overweight-to-obese adults

Ruohan Zhang¹Jintao Guo²Jingyuan Sun¹JINFA GU^1*

• ¹Universiti Sains Malaysia - Kampus Kejuruteraan, Nibong Tebal, Malaysia
• ²Beijing Sport University, Beijing, China

Background: Low-volume high-intensity interval exercise (Lv-HIIE) is a time-efficient training strategy, but little is known about how psychophysiological stress, as reflected by endocrine markers, is associated with perceived exercise experiences in overweight-to-obese adults. More specifically, research on ACTH-and cortisol-related stress responses during multi-week Lv-HIIE is very limited, and no existing studies have examined how these hormonal patterns are related to perceptual outcomes. Purpose: This study examined the associations of ACTH and cortisol responses with perceptual outcomes during a 10-week Lv-HIIE intervention and whether these associations changed across repeated sessions. Methods: Thirty-two inactive adults (11 males, 21 females; 28.3 ± 4.9 years) with overweight or obesity completed 30 Lv-HIIE sessions over 10 weeks, HIIE consisted of 8 × 1-minute work intervals performed at 90% of maximal aerobic speed (MAS), separated with 75-second recovery periods. Perceptual responses (affective valence, arousal, perceived exertion, perceived recovery, and enjoyment) and stress markers (ACTH, cortisol) were collected at sessions 1, 15, and 30. Heart-rate responses and body-composition measures were also assessed. Results: Lv-HIIE produced small but significant improvements in body composition and aerobic fitness (%BF, WHR, V̇ O₂max, MAS; all p<0.01). Physiological strain decreased, with HR and %HRmax lower in S15 and S30 than S1 across most work intervals (p<0.05; ES=0.39-1.73). Affective valence improved from negative in S1 (−0.53±0.44) to positive in S15 and S30 (p<0.001; ES=0.48-1.29), while RPE decreased and perceived recovery increased (p<0.02; ES=0.47-2.86). Enjoyment also increased (PACES: 97.0 → 110.8; p<0.001; ES > 0.67). ACTH and cortisol showed positive correlations with HR and RPE (r=0.40-0.61; p<0.03) and negative correlations with affective valence, recovery, and enjoyment (r=−0.36 to −0.56; p<0.05). Conclusion: Endocrine stress markers (ACTH and cortisol) were significantly associated with perceptual responses during the 10-week Lv-HIIE, with the strength of their correlations changing across the exercise period. These findings suggest that Lv-HIIE may promote improved perceptual tolerance and affective adaptation during training in adults with excess body weight.