Physical exercise improves memory in sedentary middle- aged adults: Are these exercise- induced benefits associated with S- Klotho and 1,25-dihydroxivitamin D? The FIT-AGEING randomized controlled trial

Abstract

We aimed to investigate the effect of three types of exercise interventions on memory (i.e., immediate memory (IM), long- term memory (LTM), and recognition). We also investigated whether exercise- induced changes in circulating S- Klotho and 1,25- dihydroxivitamin D (1,25(OH)2D) levels were related to those observed in memory in healthy middle- aged sedentary adults. A 12- week randomized controlled trial was performed with a parallel- group design. Seventy- four participants (45– 65 years old: 53% women) were randomly assigned to (1) no exercise (control) group, (2) concurrent training based on the international physical activity recommendations (PAR) group, (3) high- intensity interval training (HIIT) group, or (4) HIIT plus whole- body electromyostimulation (HIIT- EMS) group. Memory outcomes were assessed using the Wechsler Memory Scale- third edition. S- Klotho plasma levels were determined according to a solid- phase sandwich enzyme- linked immunosorbent assay kit while 1,25(OH)2D plasma levels were measured using a DiaSorin- Liaison immunochemiluminometric analyzer. IM- Verbal Paired Associates (IM- VPA) and IM- Logical Memory (IM- LM) were improved in both the HIIT and HIIT- EMS groups compared with the control group (all p≤ 0.045). Exercise- induced changes in S- Klotho plasma levels were positively associated with those observed in IM, LTM, and recognition (all p≤ 0.007), whereas exercise- induced changes in 1,25(OH)2D plasma levels were directly related to changes in IM and LTM (all p≤ 0.048). In conclusion, a 12- week HIIT intervention with or without WB- EMS seems to be the most effective exercise program to improve IM. The significant and positive associations between exercise- induced changes in S- Klotho and 1,25(OH)2D levels with those observed in memory outcomes suggest that these factors may be potentially related to exercise- induced improvements of memory in middle- aged adults.