Mitochondria are often referred to as the powerhouse of the cell and are the organelles responsible for energy production. Normal function or ‘metabolic flexibility’ is characterised by the mitochondria’s ability to switch between fat and carbohydrate as a fuel source when required. When function is impaired symptoms such as fatigue, obesity and chronic disease may present (Pieczenik & Neustadt, 2007).
Factors Influencing Mitochondrial Function
It is recognised that various factors can impact mitochondrial function including:
- High glucose levels (Bournat & Brown, 2010; Gao et al., 2010).
- Low essential fatty acids (Abete et al., 2010; Pepe & McLennan, 2007).
- Low sex hormone levels (Miller & Duckles 2008, Pitteloud et al., 2005).
- Reduced iron stores/haemoglobin levels (Pieczenik & Neustadt, 2006; Walter et al., 2001).
- Certain medications (Neustadt & Pieczenik, 2008).
- Inflammation (Horsen et al., 2017)
Ways to Improve Mitochondrial Function
Research suggests mitochondrial function can be improved through:
- Exercise - Exercise can increase the percentage of healthy mitochondria and improve muscle function and endurance (Parikh et al., 2009).
- Fasting - Promotes your body to get rid of the mitochondria that are not functioning properly through a process called autophagy (Kwon et al. 2009).
- LCHF diets - Help to reduce glucose levels (Bournat & Brown, 2010; Gao et al., 2010) and increase essential fats, (Abete et al., 2010; Pepe & McLennan, 2007) both important factors in improving mitochondrial function.
- CoQ10 - Supplementation with CoQ10 has been shown to have clinical benefits due to its antioxidant properties and is recommended as a therapeutic option for many mitochondrial diseases (Filler et al., 2014).
The role of exercise in mitochondrial function
The mechanisms behind exercise-induced changes to mitochondrial function include:
- Recruitment of previously inactive type two muscle fibres to type one muscle fibres which have higher oxidative potential (Parikh et al., 2009).
- Increases the percentage of healthy mitochondria (Parikh et al., 2009).
- Improved insulin sensitivity (Meex et al., 2009).
High Intensity Interval Training (HIIT)
HIIT has been shown to improve mitochondrial function in previously untrained individuals. Sato et al. (2015) found that in comparison to conventional walking training, HIIT 2 times weekly for 12 weeks improves mitochondrial function within the skeletal muscle. Additionally, Jacobs et al. (2013) found that even 6 HIIT training sessions completing 8 - 10 x 60s repeated efforts of cycling at high intensity was also associated with mitochondrial function.
Frequency: Twice weekly | Intensity: High | Time: 20 minutes
Meex et al. (2009) found that resistance training once a week could increase recruitment of previously inactive type two fibres and the capacity to store fatty acids. This can result in the restoration of appropriate mitochondrial function and improved insulin sensitivity. The protocol used in this study incorporated resistance training at 55% 1RM (repetition max) focusing on main muscle groups and aerobic exercise for 30 minutes 2 times a week.
Frequency: Twice weekly | Intensity: 55% 1RM | Time: 30 minutes
Mitochondrial dysfunction and metabolic inflexibility can result in symptoms such as fatigue, obesity and chronic disease. As highlighted in this article, lifestyle modification plays a key role to improving the health of mitochondria. In particular, both resistance and HIIT exercise was shown to have positive effects on function.
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