Acute Arterial Stiffness Responses To On-Ball Kneeling And Sitting In Healthy Young Adults:Effects Of Exercise Fragmentation And Exercise Order

Purpose: To investigate whether more arterial stiffness changes could be induced by fragmented balance exercise on Swiss ball in kneeling/sitting posture,and to examine the role exercise order played in the modulation of arterial stiffness when on-ball kneeling and on-ball sitting were combined in the same session.Methods: Twenty-three healthy young adults(23.8 ± 0.3 years)performed seven trials in a randomized crossover fashion: non-exercise control(CON),K(on-ball kneeling,5 min),f K(fragmented on-ball kneeling,2×2.5 min),S(on-ball sitting,5 min),f S(fragmented onball sitting,2×2.5 min),SK(5-min sitting before 5-min kneeling)and KS(5-min kneeling before 5-min sitting).Arterial stiffness assessed by the Cardio-ankle vascular index(CAVI)and heart rate variability(HRV)were measured at baseline(BL),immediately(0 min),10,20 and 30 min after intervention.CAVI changes from BL in the above trials(ΔCAVI)were used for analysis.Area under curve(AUC)of ΔCAVI was calculated for SK and KS.Results: ΔCAVI remained unaltered throughout the procedure in CON trial.Immediately after exercise,ΔCAVI in K and f K trials decreased(P < 0.05)and reverted to baseline at 30 min only in K.At 30 min,ΔCAVI in f K remained lower than that of CON and K.However,ΔCAVI increased significantly(P < 0.05)at 0 min in S and f S trials and returned to baseline at 10 min.Immediately after exercise,ΔCAVI in SK and KS trials decreased(P <0.05).Most importantly,there was still significant difference in ΔCAVI at 20 min between CON and KS trail(P < 0.05).The seven protocols did not have a significant effect on heart rate variability.Conclusion: Compared to continuous kneeling,fragmentated kneeling was associated with superior effects on systemic arterial stiffness in healthy young adults,while fragmented sitting exerted no additional effects.When kneeling and sitting were combined,kneeling before sitting elicited more arterial stiffness improvements than sitting before kneeling.