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

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-min work intervals performed at 90% of maximal aerobic speed (MAS), separated with 75-s 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, V̇O 2 max, 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.