How Resistance Training Enhances the Powerhouse of the Cell

Mitochondria are the cellular organelles responsible for aerobic adenosine triphosphate (ATP) production, which makes mitochondrial health very important to overall cellular function. The abundance and functional characteristics of mitochondria within an organ influence its physiological function.

As noted in a previous article, aging is synonymous with reduced skeletal muscle mitochondrial density and function⁽¹⁾, which is associated with reduced exercise capacity.

Conversely, the number and functionality of skeletal muscle mitochondria positively correlate with exercise capacity in healthy humans.

Although aerobic exercise is known to be a potent regulator of skeletal muscle oxidative capacity, the effect or resistance exercise on skeletal muscle bioenergetics remains poorly understood.

There are only a handful of studies attempting to determine the effect of resistance training on skeletal muscle mitochondrial function.

As such, a significant knowledge gap remains concerning the effect of resistance training on skeletal muscle respiratory capacity and function. A recent study investigated the effect of chronic resistance exercise on skeletal muscle mitochondrial respiratory function⁽²⁾.

Major Findings

The major finding is that resistance training elicits both quantitative and qualitative adaptations in skeletal muscle mitochondrial respiration indicating that resistance training is a means of augmenting mitochondrial respiratory capacity and function in skeletal muscle.

A novel finding of the current study was that resistance training significantly increased skeletal muscle mitochondrial respiration. To my knowledge, this is the first prospective study to show that chronic resistance training augments skeletal muscle mitochondrial respiration.

Specifically, this research show a marked increase in mitochondrial respiration coupled to ATP production after resistance training. These data show that the respiratory capacity and perhaps more importantly, the ATP-producing capacity of skeletal muscle mitochondria significantly increased after resistance training.

Resistance training significantly increased mitochondrial respiratory capacity. These findings are similar to those showing that mitochondrial respiratory capacity is greater in endurance-trained individuals.

Compared with that in untrained individuals endurance training significantly increased mitochondrial respiratory capacity.

Figure: Skeletal muscle mitochondrial respiration demonstrating mitochondrial respiratory capacity per mg-wet weight of muscle tissue was increased by resistance training⁽²⁾

The current findings from this research are similar to those showing that mitochondrial respiratory capacity is greater in endurance-trained individuals compared with that in untrained individuals⁽³⁾.

Collectively, this suggests that like aerobic exercise training, resistance training increases coupled mitochondrial respiration and mitochondrial respiratory capacity.

In addition to quantitative alterations in respiratory capacity, chronic resistance training brings about qualitative changes in skeletal muscle mitochondria.

Summary

To the best of my knowledge, this is the first study to comprehensively determine the effect of chronic resistance training on mitochondrial respiratory capacity within the skeletal muscle.

These novel findings demonstrate that a 12-week resistance training program results in both qualitative and qualitative adaptations in skeletal muscle mitochondria of young healthy adults.

These changes seem to occur with modest changes in mitochondrial proteins and mRNA. Collectively, these findings demonstrate that chronic resistance training improves mitochondrial respiratory function within the skeletal muscle.

The benefits of resistance training are extensive and well documented. Resistance training can improve mitochondrial function, which can help mitochondria work better and muscles contract properly. In addition to enhancing strength, lean mass and function, resistance training can also promote mitochondrial biogenesis and enhance energy production.

When paired with proper nutrition, sufficient protein intake, and other healthy lifestyle factors such as sleep and hydration, resistance training contributes not only to a strong and well-defined physique you can be proud of, but also one that is healthy down to the cellular level.

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References:
    1.    Short KR, Bigelow ML, Kahl J, et al: Decline in skeletal muscle mitochondrial function with aging in humans. Proc Natl Acad Sci U S A 102:5618-23, 2005
    2.    Porter C, Reidy PT, Bhattarai N, et al: Resistance Exercise Training Alters Mitochondrial Function in Human Skeletal Muscle. Med Sci Sports Exerc 47:1922-31, 2015
    3.    Jacobs RA, Lundby C: Mitochondria express enhanced quality as well as quantity in association with aerobic fitness across recreationally active individuals up to elite athletes. J Appl Physiol (1985) 114:344-50, 2013