Recently I asked my students if they felt tired after their online Pilates class. Some insisted they were not at all tired, but relaxed. Others said their muscles felt good. They felt stretched out. But had I asked the wrong question? What I really wanted to know was what level of exertion did they feel that they had reached after their hour with me? Were they working their bodies to fatigue?
The concept of working to fatigue is worth explaining here since some people might confuse ‘fatigue’ with ‘pain’. Working the body to fatigue does not mean until it hurts, but rather until we can no longer keep up the good form and technique of the exercise.
Back to why I am asking this question. Our bodies lose considerable muscle mass and fiber-type composition through the ageing process. Starting at age 30, muscle mass begins to decline by about 1 percent— about a third of a pound per year (now.tufts.edu/articles/power-
How exactly does one do that? Fielding’s research stressed that it’s not about how big or meaty your biceps are, but how much force a muscle can muster, and how quickly. If I truly want to help my students (and myself) combat the effects of the ageing process, I should be thinking about the specific exercises we do in class and which type of muscles fibers they target.
Most of the skeletal muscles of the body (in non-athletes) are composed of a 50/50 balance of fast-twitch and slow-twitch fibers. Each of these two types of fibers have different functions. Fast-twitch fibers are activated when we need a sudden large movement of force. They work for shorter duration and fatigue quickly. Slow-twitch fibers are slow to contract, used for smaller movements, and are associated with endurance, postural work and core stabilization. While our muscles contain both, the ratio can differ depending on age and how we use our bodies. The Tufts researchers were particularly interested in which muscles fibers were working in the bodies of their ageing subjects and how these changed over time.
Both power (fast-twitch) and endurance (slow-twitch) are important to ageing adults, but the evidence suggests it is fast-twitch that people lose as part of the ageing process. Motor neurons innervate – or send messages to – muscle fibers, in order to stimulate movement. Fielding surmised that, with age, there is a breakdown in the way the neurons communicate with each other—the ‘big motor neurons’ are more susceptible to the ageing process than slow-twitch neurons. When the big motor neurons don’t function as well, messages don’t get through with the same efficiency. As the messages decrease, the system slows. So, when we exercise, we should not only be working to strengthen our muscles but also the neurological impulses that are being sent to them.
Perhaps one of the reasons for this decline is that as we age, we start to eliminate the sort of hardy sports and robust exercises that activate these fast-contracting muscle fibers. For example, because one of our knees is sore, we may no longer do squats or fast walking. We may always take elevators and not stairs. This means muscles at the back of the legs (hamstrings and glutes) atrophy. Ankles and feet lose mobility and strength. We feel weaker and less steady on our feet and begin to do only slow movements without any sort of vigor. This lessening of effort in turn affects functional movement in our daily life. We are no longer as good at climbing stairs, fast walking, keeping balance.
The upper body is also cruelly short-changed when we automatically reach for light not heavy weights. Many people (of all ages) have an undiagnosed stiffness/soreness in the shoulder area. Because we don’t want to strain or add to this soreness, light weights (2 or 3 lbs) become the norm. What are the implications of these decisions on a daily basis? If we do not work to fatigue the upper and lower body we lose fast-twitch fibers. Soon we will no longer be able to put things up and into a cupboard above our heads. Pick up our grandchildren. Or open a heavy door by ourselves.
According to Fielding’s research, the good news is that slow-twitch muscle fibers are much less affected as we age. With the exception of the antigravity muscles, these fibers change very little during the ageing process. Moreover, many of the exercises we are already doing in Pilates classes target postural or antigravity muscles. ‘Slower’ moves such as planks, single leg balances and abdominal core work, are all training slow-twitch and endurance. And so is traditional Pilates Arm Work done with lighter weights and more repetitions.
‘You certainly get more improvements in power if you do things faster.’
The bad news is that the majority of Pilates exercises do not target fast-twitch fibers. To engage these, we need to lift heavier weights, and add in force, changes of direction, and intensity: jumping, kicking and speeding! How realistic is this, in a Pilates class designed for older adults, when many of my students have hip or knee replacements, arthritis, osteoporosis or disk issues?
Joseph Pilates himself was a former gymnast and boxer; and among his first clients were ballet dancers and elite athletes seeking to improve their performance, as well as people recovering from injuries. The potential for athleticism and stamina is, in fact, built into many of the Pilates exercises. Sharp staccato exhales, rapid pulses, vigorous calisthenics, agility training, and jumping can be peppered into Pilates sessions if desired and when safe. With a bit of a tweak, I ask myself, could I re-design my Pilates classes to add in specific exercises that safely involve fast-twitch, as well as slow-twitch, in order to make them more functional for ageing adults? I’ll be exploring this challenge in next week’s blog.