3.3 Limitations

These studies have only been performed in mice or rat in vivo models which cannot represent humans accurately due to the high genetic diversity in background, pathologies and different lifestyles (Kra ̈nkel et al.). Sex differences have also not been accounted for because the majority of studies use male animal models (Krzesiak et al.). Additionally, the type of exercise model also differs whether if it is voluntary (i.e. wheel running) or enforced (i.e treadmill) and at what age this was administered. The type, intensity, and duration of exercise also have an impact on the results (Kra ̈nkel et al.). Furthermore, the studies thus far use aerobic exercise training as their main measure but do not assess anaerobic long-term alternatives such as resistance, weight and balance training (Adamopoulos et al.). All these factors conclusively could affect results and are acknowledged as limitations in this research area.