Effects of the SmartACT Intervention on Motor and Psychological Variables in Adolescent Athletes: A Controlled Trial...

Background/Objectives: Agility and reaction speed are critical components of sports performance and are influenced by both physical conditioning and psychological state. Interventions such as SmartACT, which integrate mindfulness, acceptance, and commitment, guided imagery and hypnosis techniques are still underexplored in high-performance sport, despite their potential to affect both psychological and motor dimensions. Methods: This 7-week controlled trial investigated the effectiveness of SmartACT in reducing psychological and somatic symptoms and enhancing motor performance in adolescent athletes. A total of 193 athletes aged 15-18 years were assigned to three groups: SmartACT (n = 69), MAC (Mindfulness-Acceptance-Commitment, the standardized Gardner & Moore protocol; n = 65), and a control group (n = 59). Agility was measured using the T-Drill Agility Test with Microgate electronic timing, and reaction speed was assessed using BlazePod devices. Psychological and somatic symptoms were evaluated using the Depression, Anxiety, and Stress Scale (DASS-21) and the Ghent Multidimensional Somatic Complaints Scale (GMSCS). Results: The SmartACT group showed significantly improved agility (MD = -1.07 s, p < 0.001, d = 2.50, 95% CI [1.79, 3.35]), faster reaction times (MD = -643.75 ms, p < 0.001, d = 0.85, 95% CI [0.35, 1.41]), and a higher number of BlazePod touches (MD = +2.53, p < 0.001, d = 1.43, 95% CI [0.87, 2.07]). Psychological symptoms (DASS-21) and somatic complaints (GMSCS) decreased significantly more than in the MAC and control groups. Conclusions: SmartACT appears to be an effective hybrid psychological intervention to simultaneously improve physical performance and reduce psychological and psychosomatic distress in adolescent athletes.