For some of you, especially clients of mine who already participate in CrossFit or CrossFit-style conditioning, this blog may be filed under the, "Yeah, I knew that already" category. For others, keep reading and pay attention because we see this all too often with ageing populations.
It turns out, being active as you age isn't enough. Instead, you need to push your limits by doing something like high intensity interval training (HIIT) a few times a week.
First, the fancy science jargon:
Enhanced Protein Translation Underlies Improved Metabolic and Physical Adaptations to Different Exercise Training Modes in Young and Old Humans
The molecular transducers of benefits from different exercise modalities remain incompletely defined. Here we report that 12 weeks of high-intensity aerobic interval (HIIT), resistance (RT), and combined exercise training enhanced insulin sensitivity and lean mass, but only HIIT and combined training improved aerobic capacity and skeletal muscle mitochondrial respiration. HIIT revealed a more robust increase in gene transcripts than other exercise modalities, particularly in older adults, although little overlap with corresponding individual protein abundance was noted. HIIT reversed many age-related differences in the proteome, particularly of mitochondrial proteins in concert with increased mitochondrial protein synthesis. Both RT and HIIT enhanced proteins involved in translational machinery irrespective of age. Only small changes of methylation of DNA promoter regions were observed. We provide evidence for predominant exercise regulation at the translational level, enhancing translational capacity and proteome abundance to explain phenotypic gains in muscle mitochondrial function and hypertrophy in all ages.
If you remember back to your high school science days, you should remember a little organelle found inside your cells known as the mitochondrion. Also known as the cell's "powerhouse." Well, as we age, the ability for our mitochondria to produce energy energy diminishes, or becomes less efficiently, so we tend to have less and less energy. Sure, we are going to see decreased energy and performance as you get older, but you might as well fight like hell to stay as spry and energetic as possible. Here's how.
For those of you not familiar with it, HIIT training involves short bursts of intense activity, interspersed with recovery periods. Clearly I am biased because I am the head of CrossFit Orangeville, but this is exactly what we promote at CF Orangeville - intensity.
Anyways, the above study assigned groups of people either aged 18-30 or 65-80 years old to 3 months of either HIIT training, just resistance training, or a combination of the two. What they found was that although the younger group (18-30 year olds) improved their ability to generate energy via their mitochondria by 49% using interval training, the older group (65-80 year olds) improved by 69%! Participants also saw additional improvements in cardiovascular markers such as lung, heart, and circulation health.
It should be noted that the resistance training only groups also saw tremendous health improvements from resistance training alone, but didn't reap the same energy benefits the HIIT participants received.
More from the study:
High intensity aerobic interval training (HIIT) involves repeating short bouts of activity at near-maximal intensity, which rapidly and robustly increases aerobic capacity, mitochondrial respiration, and insulin sensitivity in young people (Burgomaster et al., 2008; Irving et al., 2011). Resistance training (RT) reverses sarcopenia and age-related declines in myosin heavy-chain gene transcripts and synthesis rates of muscle proteins (Balagopal et al., 2001), but a comprehensive gene transcripts and proteome comparison with aerobic training has not been performed. Combined training (CT) offers many benefits of both aerobic and resistance training, although the intensity of aerobic and resistance components are lower than either HIIT or standard RT programs (Irving et al., 2015). Lower exercise intensity may limit training adaptations (Ross et al., 2015), particularly of mitochondria (MacInnis et al., 2016).
So what was noted was the fact that lower exercise, although somewhat beneficial to the participants, was not as beneficial as high intensity training was. I tend to like to summarize findings like that as simple as possible. I also keep in mind that our bodies are computers that feed on stimulus. What I mean by that is that having our bodies perform a specific action creates a stimulus. Stimuli create a reaction for the body to overcome. For example, exercising (stimulus) causes sore muscles (reaction), which in turn makes us stronger. In order to be better or more efficient at producing energy, you must create a stimulus (intense exercise) worthy enough of challenging what the body can currently do. Unfortunately for most people, is that they are either apprehensive about pushing themselves into that "uncomfortable" zone, or simply have never really attempted to push that hard.
Although it is not the case 100% of the time, for the most part, creating a stimulus for the body that goes beyond what is the current status quo can cause a reaction or adaptation that improves our overall health - you just need to go to that place that is momentarily uncomfortable.
Tyler Robbins B.Sc. CSCS
Director of Fitness
Head of CrossFit