Resistance exercise and control of cerebral blood flow in type 2 diabetes

Abstract

Keywords Bloodpressure.Cerebralautoregulation.Cerebralcirculation.Exercise.TranscranialDopplerTo the Editor: The challenge in diabetes care is to optimisemetabolic control to slow progression to vascular disease.In individuals with type 2 diabetes this may be achieved atleast in part by behavioural modification including regularphysical activity. In their recent article in Diabetologia,Praet and van Loon [1] comprehensibly and conciselyaddress the need for revision of the current guidelinesregarding the prescription of exercise for individuals withtype 2 diabetes, given the lack of information provided bycurrent exercise programmes on the preferred type andintensity of exercise.The combination of endurance and resistance exercisehas the potential to increase adherence and compliancerates, as it renders programmes more varied [1]. Loss ofskeletal muscle mass is one of the main factors responsiblefor the increase in the incidence of type 2 diabetes with age.Deconditioning (as a result of physical inactivity) andresistance exercise are associated with opposing adapta-tions. Resistance exercise provides better metabolic control[2], mitigates disuse-associated tendon stiffness andincreases skeletal muscle mass, which improves wholebody glucose disposal [3]. Not surprisingly, greater focuson resistance exercise has been recommended for type 2diabetes, specifically for the subgroup of sarcopenic orseverely deconditioned older patients [4].Resistance and endurance exercise have different car-diovascular effects. Resistance-type activities produce aconsiderably larger increase in arterial pressure, because ofthe mechanical compression of blood vessels together withrepeated Valsalva-like manoeuvres [5]. Unlike aerobicexercise, resistance training affects central arterial compli-ance in healthy men [6]. Although acute changes in arterialblood pressure during physiological challenges are trans-mitted to the cerebral circulation, under normal conditions,cerebral blood flow tends to return to its baseline valuewithin a few seconds [7]. Cerebral vasoconstrictionconstantly plays a protective role during exercise ofmoderate to heavy intensity, in particular when pulsepressure exceeds the autoregulatory range [8]. Whenautoregulatory mechanisms are failing or overwhelmed byacute blood pressure upsurges beyond the autoregulatoryrange (e.g. in serious hypertension), brain blood flow